Synthesis method of compound L635

Abstract

The present application relates to a method for synthesizing a spasmolytic polypeptide metaplasia modeling agent compound L635. Through reasonable route design, combined with chiral synthesis, electrochemical synthesis, recrystallization and chiral resolution, four configurations of compound L635 can be prepared, and the structure of the compound and its absolute configuration are confirmed by using rotation spectrum, circular dichroism spectrum, chiral chromatography, mass spectrum, hydrogen spectrum, carbon spectrum, combined with ECD, calculated hydrogen spectrum, calculated carbon spectrum and DP4+ and other quantum chemistry, which is of great significance for studying the SPEM model, the pathogenesis of intestinal metaplasia and gastric cancer, as well as drug screening and efficacy evaluation.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and in particular to a method for synthesizing compound L635. Background Art

[0002] Spasmolytic polypeptide-expressing metaplasia (SPEM) is a metaplastic state after gastric mucosa damage, and is considered to be a precancerous pathophysiological form of intestinal metaplasia and gastric cancer. Compound L635 (the structure is shown in the following formula (I)) is an important reagent for constructing a SPEM model. Therefore, providing a preparation method of compound L635, especially compounds of different configurations thereof, is of great significance for studying the SPEM model, the pathogenesis of intestinal metaplasia and gastric cancer, as well as drug screening and efficacy evaluation.

[0003]

[0004] The synthesis route of compound L635 in the prior art solution (patent: US5348953) is as follows:

[0005]

[0006] This synthetic route only constructs one of the chiral centers, and no synthetic study is conducted on the other chiral center (the "*" mark in formula (I)). The construction of the chiral center on the β-lactam ring is based on the separation of corresponding isomers 6 (R) and 6 (S), and the enantiomers have the same physicochemical properties, solubility and melting point, etc. Therefore, it is difficult to obtain a product with high chiral purity through chiral separation. The key intermediate for the construction of the other chiral center is compound 11. For the synthesis of the precursor compound 4 of compound 11 and the construction of the chiral center, the following methods were attempted:

[0007]

[0008] Among them, method A is to react compound 4-methylbenzaldehyde with compound 12 (D-phenylglycine amide) to form an imine, and then react with a Grignard reagent to generate compound 13, and then reduce the terminal double bond and remove the phenylacetamide group to obtain the R-configured compound 4. However, this method has many steps, and the reduction and removal of the phenylacetamide group reaction takes 5 days. It is also difficult to ensure the high yield as reported in the actual production process.

[0009] In methods B and C, it is difficult to obtain compound 4 of a single configuration regardless of whether butyl lithium or organomagnesium is used.

[0010] Method D is to add chiral ligand (S)-tert-butylsulfenamide to butyraldehyde to form imine 17, and then form compound 18 under the catalysis of bis(acetonitrile)[(1,2,5,6-η)-1,5-cyclooctadiene]rhodium(I)-tetrafluoroborate, and then hydrolyze with hydrochloric acid to obtain R-configured compound 4. However, the catalyst used in this reaction is relatively complex and expensive.

[0011] In method E, compound 19 is catalyzed by compound 20 to obtain compound 4 of S configuration. However, the process of the reaction between borane and α-[(1S)-1-amino-2-methylpropyl]-α-phenylbenzyl alcohol to form compound 17 is difficult to control and difficult to apply industrially. Summary of the invention

[0012] Based on this, the present application provides a method for synthesizing compounds L635 with different configurations, and the compound L635 prepared by the synthesis method has a single configuration and high production efficiency, low cost, and simple and easy-to-control steps.

[0013] The specific technical solutions are as follows:

[0014] A method for synthesizing compound L635 comprises the following steps:

[0015]

[0016] S1: reacting compound 1 with (R)-tert-butylsulfenamide or (S)-tert-butylsulfenamide to prepare compound 2(S) or compound 2(R);

[0017] S2: subjecting compound 2(S) or compound 2(R) to a Grignard reaction with n-propylmagnesium chloride to prepare compound 3(1R, 2S) or compound 3(1S, 2R);

[0018] S3: subjecting compound 3(1R, 2S) or compound 3(1S, 2R) to a deprotection reaction in the presence of an acid to prepare compound 4(R) or compound 4(S);

[0019] S4: Compound 4(R) or Compound 4(S) is coupled with Compound 6 in the presence of an organic base via N,N'-carbonyldiimidazole (CDI) to prepare Compound 7(R) or Compound 7(S);

[0020] S5: subjecting compound 7(S) or compound 7(R) to a deprotection reaction to prepare compound 8(S) or compound 8(R);

[0021] S6: subjecting compound 8(S) or compound 8(R) to a condensation reaction with N,N-dimethyl-N'-ethylethylenediamine in the presence of an organic base and a condensing agent to prepare compound 9(S) or compound 9(R);

[0022] S7: Chirally separate compound 9(S) to prepare compound 9(1S, 2R) and compound 9(1S, 2S), or chirally separate compound 9(R) to prepare compound 9(1R, 2R) and compound 9(1R, 2S).

[0023] In one embodiment, the reaction in step S1 is carried out in the presence of Cs2CO3; and / or,

[0024] The reaction temperature is 45°C to 60°C, and the reaction time is 10h to 20h.

[0025] In one embodiment, in the Grignard reaction in step S2, n-propylmagnesium chloride is added at -5 to 5°C, and then reacted for 2h to 6h.

[0026] In one embodiment, the deprotection reaction in step S3 is carried out by adding an acid at -5 to 5°C and then reacting at room temperature for 1 to 3 hours; and / or

[0027] The method also includes adding L-tartaric acid or D-tartaric acid to compound 4(R) or compound 4(S) obtained by the deprotection reaction and stirring for 6 hours to 12 hours at room temperature, collecting the product and recrystallizing it with isopropanol.

[0028] In one embodiment, the organic base in step S4 is N,N-diisopropylethylamine (DIEA) or triethylamine; and / or

[0029] The coupling reaction was carried out under reflux for 20 to 30 hours.

[0030] In one embodiment, the deprotection reaction in step S5 is carried out in the presence of Pd / C and hydrogen, the reaction temperature is room temperature, and the reaction time is 15h to 22h; or,

[0031] The deprotection reaction in step S5 is carried out in the presence of NiCl2·6H2O and NaBH4, at room temperature, for 10 min to 20 min.

[0032] In one embodiment, the organic base in step S6 is N,N-diisopropylethylamine (DIEA) or triethylamine; and / or

[0033] The condensing agent is 1-hydroxybenzotriazole (HOBT) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC); and / or

[0034] The condensation reaction is carried out at room temperature and the reaction time is 3h to 15h.

[0035] In one embodiment, the chiral separation in step S7 is performed by chromatography, and the mobile phase used in the chromatography is n-hexane and isopropanol in a volume ratio of (75-90):(25-10), which contains diethylamine accounting for 1.5‰ to 2.5‰ of the total volume of the n-hexane and isopropanol.

[0036] In one embodiment, the synthesis method of compound 6 in step S4 comprises the following steps:

[0037]

[0038] Compound 5 is mixed with benzyl glycolate, sodium benzenesulfonate, tetraethylammonium p-toluenesulfonate and a solvent, and an electrode is immersed in the obtained mixed solution to carry out an electrochemical reaction, thereby preparing compound 6.

[0039] In one embodiment, the electrochemical reaction is carried out at a temperature of 5°C to 25°C and a constant current of 0.4A to 1A.

[0040] The above-mentioned synthesis method of compound L635, through reasonable route design, combined with steps such as chiral synthesis and chiral resolution, can prepare compounds with four configurations of compound L635, and the compound structure and its absolute configuration are confirmed by multiple characterization methods, which is of great significance for studying the SPEM model, the pathogenesis of intestinal metaplasia and gastric cancer, as well as drug screening and efficacy evaluation.

[0041] In addition, the four configurations of compound L635 prepared by the synthesis method all have a single configuration, and have high production efficiency, low cost, simple and easy-to-control steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 For compound 4(R) 1 H NMR spectrum;

[0043] Figure 2 For compound 6 1 H NMR spectrum;

[0044] Figure 3 is the chiral chromatogram of compound 9 (1S, 2R);

[0045] Figure 4 Compound 9(1S,2R) 1 H NMR spectrum;

[0046] Figure 5 Compound 9(1S,2R) 13 C NMR spectrum;

[0047] Figure 6is the chiral chromatogram of compound 9 (1S, 2S);

[0048] Figure 7 Compound 9(1S,2S) 1 H NMR spectrum;

[0049] Figure 8 Compound 9(1S,2R) 13 C NMR spectrum;

[0050] Fig. 9 is the chiral chromatogram of compound 9 (1R, 2R);

[0051] Fig.10 Compound 9(1R,2R) 1 H NMR spectrum;

[0052] Fig.11 Compound 9(1R,2R) 13 C NMR spectrum;

[0053] Fig.12 is the chiral chromatogram of compound 9 (1R, 2S);

[0054] Fig.13 Compound 9(1R,2S) 1 H NMR spectrum;

[0055] Fig.14 Compound 9(1R,2S) 13 C NMR spectrum;

[0056] Fig.15 It is the ECD chromatogram of compound 9 (1S, 2R) (theoretical level: B3LYP / 6-311+g(2d, p), free energy correction: 0.1ev, wavelength correction: -15nm);

[0057] Fig.16 It is the ECD chromatogram of compound 9 (1S, 2S) (theoretical level: B3LYP / 6-311+g(2d, p) level, free energy correction: 0.3ev, wavelength correction: 19nm);

[0058] Fig.17 It is the ECD chromatogram of compound 9 (1R, 2R) (theoretical level: B3LYP / 6-311+g(2d, p) level, free energy correction: 0.3ev, wavelength correction: 19nm);

[0059] Fig.18This is the ECD chromatogram of compound 9 (1R, 2S) (theoretical level: B3LYP / 6-311+g(2d, p) level, free energy correction: 0.3ev, wavelength correction: -17nm). DETAILED DESCRIPTION

[0060] The synthetic method of compound L635 of the present application is further described in detail below in conjunction with specific examples. The present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0061] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0062] The optional scope of the terms "and / or", "or / and", and "and / or" used in this article includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, said any and all combinations include any combination of any two related listed items, any more related listed items, or all related listed items.

[0063] As used herein, "one or more" refers to any one, any two, or any two or more of the listed items.

[0064] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0065] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0066] The percentage contents involved in this application, unless otherwise specified, refer to mass percentage for solid-liquid mixing and solid-solid mixing, and refer to volume percentage for liquid-liquid mixing.

[0067] The percentage concentrations mentioned in this application, unless otherwise specified, refer to the final concentration, which refers to the percentage of the added component in the system after the addition of the component.

[0068] The temperature parameters in this application, unless otherwise specified, allow for both constant temperature treatment and treatment within a certain temperature range. The constant temperature treatment allows the temperature to fluctuate within the accuracy range of instrument control.

[0069] The room temperature in the present application generally refers to 4°C to 30°C, preferably 20±5°C.

[0070] Some examples of the present application provide a method for synthesizing compound L635, comprising the following steps:

[0071]

[0072] S1: reacting compound 1 with (R)-tert-butylsulfenamide or (S)-tert-butylsulfenamide to prepare compound 2(S) or compound 2(R);

[0073] S2: subjecting compound 2(S) or compound 2(R) to a Grignard reaction with n-propylmagnesium chloride to prepare compound 3(1R, 2S) or compound 3(1S, 2R);

[0074] S3: subjecting compound 3(1R, 2S) or compound 3(1S, 2R) to a deprotection reaction in the presence of an acid to prepare compound 4(R) or compound 4(S);

[0075] S4: Compound 4(R) or Compound 4(S) is coupled with Compound 6 in the presence of an organic base via N,N'-carbonyldiimidazole (CDI) to prepare Compound 7(R) or Compound 7(S);

[0076] S5: subjecting compound 7(S) or compound 7(R) to a deprotection reaction to prepare compound 8(S) or compound 8(R);

[0077] S6: reacting compound 8(S) or compound 8(R) with N,N-dimethyl-N'-ethylethylenediamine in the presence of an organic base and a condensing agent to prepare compound 9(S) or compound 9(R);

[0078] S7: Chirally separate compound 9(S) to prepare compound 9(1S, 2R) and compound 9(1S, 2S), or chirally separate compound 9(R) to prepare compound 9(1R, 2R) and compound 9(1R, 2S).

[0079] It can be understood that compound 9(1S, 2R) and compound 9(1S, 2S), compound 9(1R, 2R) and compound 9(1R, 2S) are different configurations of compound L635.

[0080] In one example, the reaction in step S1 is carried out in the presence of Cs2CO3.

[0081] In one example, the reaction temperature in step S1 is 45°C to 60°C, and the reaction time is 10h to 20h. Specifically, the reaction temperature includes but is not limited to: 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C; the reaction time includes but is not limited to: 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h.

[0082] Without limitation, the molar equivalent ratio of (R)-tert-butylsulfenamide or (S)-tert-butylsulfenamide, CS2CO3 and compound 1 in step S1 is 0.8-1.2:0.8-1.2:1.

[0083] In one example, the reaction solvent in step S1 is heptane.

[0084] In one example, the Grignard reaction in step S2 is performed by adding the n-propylmagnesium chloride at -5 to 5°C and then reacting for 2 to 6 hours. Specifically, the reaction time includes but is not limited to: 2 hours, 3 hours, 4 hours, 5 hours, and 6 hours.

[0085] In one example, the reaction solvent in step S2 is methyl methyl ketone (MTBE).

[0086] Without limitation, the molar equivalent ratio of n-propylmagnesium chloride to compound 2(S) or compound 2(R) is 1 to 2:1.

[0087] In one example, in the deprotection reaction in step S3, an acid is added at -5 to 5° C., and then reacted at room temperature for 1 to 3 hours. Without limitation, the acid is hydrochloric acid.

[0088] In one example, the solvent for the deprotection reaction in step S3 is ethyl acetate.

[0089] Without limitation, the volume ratio of the solvent, 4N HCl in ethyl acetate solution and compound 3(1R, 2S) or compound 3(1S, 2R) is 3-10:3-10:1.

[0090] In one example, after the deprotection reaction in step S3 is completed, L-tartaric acid or D-tartaric acid is added to compound 4(R) or compound 4(S) obtained by the deprotection reaction and stirred at room temperature for 6h to 12h, and the product is collected and recrystallized with isopropanol.

[0091] In one example, the organic base in step S4 is N,N-diisopropylethylamine (DIEA) or triethylamine.

[0092] In one example, the coupling reaction in step S4 includes a condition of reacting under reflux conditions for 20h to 30h. Specifically, the reaction time includes, but is not limited to: 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h. It can be understood that reflux refers to the formation of steam in the reaction system during the reaction and the condensation and subsequent flow back into the reaction system. Specifically, the reflux temperature is 76°C to 83°C.

[0093] In one example, the solvent for the coupling reaction in step S4 is acetonitrile.

[0094] Without limitation, the molar equivalent ratio of CDI, compound 4(S) or compound 4(R), DIEA and compound 6 is 1-2:1-2:1-3:1.

[0095] In one example, the deprotection reaction in step S5 is carried out in the presence of NiCl2·6H2O and NaBH4, the reaction temperature is room temperature, and the reaction time is 10 min to 20 min. Specifically, the reaction time includes but is not limited to: 100 min, 110 min, 120 min, 130 min, 140 min, 150 min, 160 min, 170 min, 180 min, 190 min, 200 min.

[0096] In one example, the solvent for the reaction in step S5 is methanol.

[0097] Without limitation, the molar equivalent ratio of sodium borohydride and nickel chloride hexahydrate to compound 8(S) or compound 8(R) is 2-4:7-10:1.

[0098] In one example, the deprotection reaction in step S5 is carried out in the presence of Pd / C and hydrogen, the reaction temperature is room temperature, and the reaction time is 15h to 22h.

[0099] In one example, the organic base in step S6 is N,N-diisopropylethylamine (DIEA) or triethylamine.

[0100] In one example, the condensing agent in step S6 is 1-hydroxybenzotriazole (HOBT) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC). Further, the molar equivalent ratio of HOBT to EDC is 1-2:1-2.

[0101] In one example, the condensation reaction in step S6 is carried out at room temperature for 3 h to 15 h.

[0102] In one example, the solvent for the condensation reaction in step S6 is N,N-dimethylformamide (DMF).

[0103] Without limitation, the molar equivalent ratio of N,N-dimethyl-N'-ethylethylenediamine, EDC, HOBt to compound 8(S) or compound 8(R) is 1-2:1-2:1-2:1; the equivalent ratio of DIEA to compound 8(S) or compound 8(R) is 2-6:1.

[0104] In one example, the chiral separation in step S7 is performed by chromatography, and the mobile phase used in the chromatography is n-hexane and isopropanol in a volume ratio of (75-90): (25-10), wherein diethylamine is included in an amount of 1.5‰ to 2.5‰ of the total volume of the n-hexane and isopropanol. Specifically, the volume ratio of n-hexane to isopropanol includes, but is not limited to, 75:25, 76:24, 77:23, 78:22, 79:21, 80:20, 81:19, 82:18, 83:17, 84:16, 85:15, 90:10. The volume ratio of diethylamine includes, but is not limited to, 1.5‰, 1.6‰, 1.7‰, 1.8‰, 1.9‰, 2‰, 2.1‰, 2.2‰, 2.3‰, 2.4‰, 2.5‰.

[0105] In one example, the chromatography method further comprises one or more of the following conditions:

[0106] (1) Column temperature is 28℃~32℃;

[0107] (2) Flow rate: 0.8-1.2 mL / min;

[0108] (3) The detection wavelength is 210nm~220nm.

[0109] In addition, the current synthetic route of compound L635 does not provide a synthetic method for its starting material compound 22. There is a method that provides a synthetic route as follows:

[0110]

[0111] This method prepares compound 22 by acetylation of the aldehyde enol hydroxyl group and a [2+2] cycloaddition reaction with chlorosulfonyl isocyanate. However, the yields of the two steps are 65% and 36%, respectively, which are very low, especially for the [2+2] cycloaddition reaction.

[0112] Based on this, the present application further provides a method for synthesizing compound 6 (compound 1 in the current synthesis route of compound L635), which can prepare compound 6 in one step through electrochemical reaction with high reaction yield.

[0113] In one example, the synthesis method of compound 6 in step S4 includes the following steps:

[0114]

[0115] Compound 5 is mixed with benzyl glycolate, sodium benzenesulfonate, tetraethylammonium p-toluenesulfonate and a solvent, and an electrode is immersed in the obtained mixed solution to carry out an electrochemical reaction, thereby preparing compound 6.

[0116] In one example, the electrochemical reaction is performed at a temperature of 5° C. to 25° C. and a constant current of 0.4A to 1A. Specifically, the constant current includes but is not limited to: 0.4A, 0.5A, 0.6A, 0.7A, 0.8A, 1A.

[0117] In one example, the solvent is acetonitrile.

[0118] Without limitation, the molar equivalents of benzyl glycolate, sodium benzenesulfonate, tetraethylammonium p-toluenesulfonate, solvent and compound 5 are 2-4:0.3-0.5:0.1:0.4:1 respectively;

[0119] The following are specific examples. Unless otherwise specified, the raw materials used in the examples are all commercially available products.

[0120] Example 1 Compound Synthesis and Structural Characterization

[0121] The synthetic routes are summarized as follows:

[0122]

[0123] Synthesis and characterization of compounds 2(R) and 2(S)

[0124] In a 500 ml flask, p-tolualdehyde (compound 1, 20 g, 166 mmol), (R)-tert-butylsulfenamide or (S)-tert-butylsulfenamide (22.4 g, 163.3 mmol), CS2CO3 (56.4 g, 173.1 mmol) were added. Heptane (160 ml) was added, and the mixture was heated to 50°C and reacted for 18 hours. After cooling to room temperature, 40 ml of water and 80 ml of toluene were added. The organic layer was separated and washed with brine, dried over sodium persulfate, and concentrated to give 2(R) and 2(S) compounds, both as colorless solids.

[0125] (E)-N-(4-Methyl-benzylidene)-(S)-tert-butanesulfenamide (2(S))

[0126] Yield: 82%, melting point: 63-64°C, 1H NMR (400MHz, CDCl3) δ8.55(s,1H),7.75(d,J=8.1Hz,2H),7.28(d,J=8.1Hz,2H),2.42(s,3H),1.26(s,9H).ESI-MS m / z:224.5[M+1] + .

[0127] (R,E)-N-(4-Methyl-benzylidene)-(S)-tert-butane-sulfenamide (2(R))

[0128] Yield: 84%, melting point: 63-64°C, 1 H NMR (400MHz, CDCl3) δ8.56(s,1H),7.75(d,J=8.1Hz,2H),7.28(d,J=8.1Hz,2H),2.42(s,3H),1.26(s,9H).ESI-MS m / z:224.5[M+1] + .

[0129] Synthesis and characterization of compounds 3(R) and 3(S)

[0130] Compound 2(R) or 2(S) (33 g, 148 mmol) was dissolved in 330 ml of methyl ethyl ketone (MTBE), and a tetrahydrofuran solution of n-propylmagnesium chloride (250 ml, 1.0 M, 250 mmol) was added dropwise at -5 to 5°C. After stirring for 4 hours, the reaction was quenched with a saturated ammonium chloride solution. The aqueous layer was extracted three times with vinyl acetate. The combined organic layer was washed with 160 ml of brine, dried over sodium sulfate, filtered, and concentrated to obtain compound 3(R) or 3(S) as a colorless solid.

[0131] N-[(R)-1-(4-Tolyl)butyl]-(S)-tert-butanesulfenamide (3(S))

[0132] Yield: 80%, melting point: 102-103°C. 1 H NMR (400MHz, CDCl3) δ7.18(d,J=8.0Hz,2H),7.13(d,J=8.0Hz,2H),4.33(td,J=8.4,2.5Hz,1H),3.35( s,1H),2.35(s,3H),1.79-1.72(m,2H),1.33-1.19(m,2H),1.17(s,9H),0.88(t,J=7.5Hz,3H).ESI-MS m / z:268.4[M] + .

[0133] N-((S)-1-(4-Tolyl)butyl)-(R)-tert-butanesulfenamide (3(R))

[0134] Yield: 80%, ESI-MS m / z: 268.4 [M] + .

[0135] Synthesis and characterization of compounds 4(S) and 4(R)

[0136] 80 g of compound 3(R) or 3(S) was dissolved in 400 ml of ethyl acetate and 400 ml of 4N hydrochloric acid / ethyl acetate solution was added dropwise at -5 to 5°C. The reaction was stirred at room temperature for 2 hours, then filtered and the solid was washed with ethyl acetate. The solid was alkalized with 5% sodium hydroxide aqueous solution in a 1-liter bottle, and the aqueous layer was washed 3 times with ethyl acetate. Then, the combined organic layer was washed with brine, filtered, and concentrated to obtain the crude 4(R) or 4(S) compound.

[0137] (S)-1-(4-Tolyl)-1-butylamine (4(S))

[0138] 21.1 g of D-tartaric acid and 460 mL of isopropanol were added to a 1-liter three-necked flask, mixed evenly, and 23 g of crude compound 4 (S) was added and stirred at room temperature for 8 hours. The solid was then filtered off, washed with a small amount of isopropanol, and dried at 55°C. The obtained solid was added with 50 mL of isopropanol and dissolved by heat at 60°C, filtered, slowly cooled to room temperature, and recrystallized to obtain a white solid 4 (S). Yield: 85%, ee%: 95.12%. [α] 20 D =-4.167°(c 0.264,CHCl3). 1 H NMR (400MHz, CDCl3) δ7.43-7.29(m,5H),6.62(s,1H),5.17(s,2H),4.69(s,1H),1. 88-1.56(m,6H),0.98(t,J=7.5Hz,3H),0.92(t,J=7.5Hz,3H).ESI-MS:164.1[M+H] + .

[0139] (R)-1-(4-Tolyl)-1-butylamine (4(R))

[0140] 21.1 g of D-tartaric acid and 460 mL of isopropanol were added to a 1-liter three-necked flask, mixed evenly, and 23 g of crude compound 4 (R) was added and stirred at room temperature for 8 hours. The solid was then filtered off, washed with a small amount of isopropanol, and dried at 55°C. The obtained solid was added with 50 mL of isopropanol and dissolved by heat at 60°C, filtered, slowly cooled to room temperature, and recrystallized to obtain a white solid 4 (R). Yield: 86%, melting point: 55-56.5°C. ee%: 97.66%. [α] 20 D = +11.767°(c 0.11,CHCl3), 1 HNMR(400MHz, CDCl3)δ7.43-7.29(m,5H),6.62(s,1H),5.17(s,2H),4.69(s, 1H),1.88-1.56(m,6H),0.98(t,J=7.5Hz,3H),0.92(t,J=7.5Hz,3H).ESI-MS m / z:164.1[M+H] + .

[0141] 1 H NMR spectrum Figure 1 shown.

[0142] Synthesis and characterization of compound 6

[0143] To a glass electrolytic cell equipped with a magnetic stirrer, lactam 5 (0.509 g, 4 mmol), benzyl glycolate (2.0 g, 12 mmol), sodium benzenesulfonate (PhSO3Na, 0.288 g, 1.6 mmol), tetraethylammonium p-toluenesulfonate (Et4NOTs, 0.241 g, 0.8 mmol) and acetonitrile (40 ml) were added. The electrode was immersed in the solution and a constant current of 0.6 amperes was applied at 10°C. The reaction was allowed to warm to room temperature until all the starting material disappeared, as monitored by thin layer chromatography. The solvent was evaporated and the product was purified by flash chromatography (ethyl acetate / petroleum ether gradient elution) to give 0.97 g of the title compound as a light yellow solid.

[0144] Benzyl 2-[(3,3-diethyl-2-azetidinone-4-oxo)oxy]acetate (6)

[0145] Yield: 83%. 1H NMR (400MHz, CDCl3) δ7.41-7.29(m,5H),6.62(s,1H),5.17(s,2H),4.69(s,1H),1.68(dd dd,J=16.4,14.3,11.6,7.4Hz,6H),0.98(t,J=7.5Hz,3H),0.92(t,J=7.5Hz,3H).ESI-MS m / z:292.1[M+H] + .

[0146] 1 H NMR spectrum Figure 2 shown.

[0147] Synthesis and characterization of compound 7(R)

[0148] Compound 4(R) (3.8 g, 23.5 mmol) was dissolved in 6 ml of dichloromethane, and a solution of N,N'-carbonyldiimidazole (CDI, 3.8 g, 23.5 mmol) dissolved in dichloromethane was added dropwise under stirring. The reaction mixture was stirred at room temperature for 15 hours. After removing the solvent, lactam 6 (7.18 g, 24.6 mmol), N,N-diisopropylethylamine (DIEA, 4 ml, 23.5 mmol) and acetonitrile (15 ml) were added in sequence. The reaction mixture was refluxed at 80°C for 24 hours. After the starting material was consumed, the reaction was concentrated under reduced pressure. Subsequently, the residue was partitioned between ethyl acetate and 1M aqueous citric acid solution and extracted with ethyl acetate (3×50 ml). The combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The crude product was purified by flash column chromatography (ethyl acetate / petroleum ether gradient elution) to give the target compound as a light yellow solid.

[0149] Benzyl 2-{[3,3-diethyl-1-((1R)-p-tolyl-butylcarbamoyl)-2-azetidinone-4-oxo]oxy}acetate (7R)

[0150] Yield: 78.9%. 1 H NMR (400MHz, CDCl3) δ7.40-7.28(m,5H),7.21-7.09(m,4H),6.93(dd,J=12.5,8.1Hz,1H),5.26-5.00(m,3H),4.88-4.68(m,2H),4.46( dd,J=25.2,17.1Hz,1H),2.32(d,J=2.6Hz,3H),1.92-1.60(m,6H),1.41-1.22(m,3H),0.97(dddd,J=13.8,9.9,8.3,5.0Hz,9H).ESI-MS m / z:481.3[M]+ .

[0151] Synthesis and characterization of compound 7(S)

[0152] Compound 4(S) (3.8 g, 23.5 mmol) was dissolved in 6 ml of dichloromethane, and a solution of N,N'-carbonyldiimidazole (CDI, 3.8 g, 23.5 mmol) dissolved in dichloromethane was added dropwise under stirring. The reaction mixture was stirred at room temperature for 15 hours. After removing the solvent, lactam 6 (7.18 g, 24.6 mmol), N,N-diisopropylethylamine (DIEA, 4 ml, 23.5 mmol) and acetonitrile (15 ml) were added in sequence. The reaction mixture was refluxed at 80°C for 24 hours. After the starting material was consumed, the reaction was concentrated under reduced pressure. Subsequently, the residue was distributed between ethyl acetate and 1M aqueous citric acid solution and extracted with ethyl acetate (3×50 ml). The combined organic layers were washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure. The crude product was purified by flash column chromatography (ethyl acetate / petroleum ether gradient elution) to obtain the target compound as a light yellow solid.

[0153] Benzyl 2-{[3,3-diethyl-1-((1S)-p-tolyl-butylcarbamoyl)-2-azetidinone-4-oxo]oxy}acetate (7S)

[0154] Yield: 82.3%, ESI-MS m / z: 481.3[M] + .

[0155] Synthesis and characterization of compound 8(S)

[0156] In a 250mL three-necked flask, compound 7(S) (6 g, 12.5 mmol) was dissolved in 40 mL of tetrahydrofuran and 10% Pd / C (1.2 g, 1.12 mmol) was carefully added. After evacuation, hydrogen was introduced and the reaction mixture was stirred at room temperature and monitored by thin layer chromatography. After 20 hours of reaction, the starting material disappeared. Filtered through diatomaceous earth and washed with 30 mL of tetrahydrofuran. The combined filtrate was concentrated and the crude product was purified by flash column chromatography (ethyl acetate / petroleum ether gradient elution) to obtain 4.4 g of compound 8(S). Yield: 90.3%.

[0157] Synthesis and characterization of compound 8(R)

[0158] Compound 7 (R) (5.6 g, 11.7 mmol) was dissolved in 30 ml of methanol, and NiCl2·6H2O (25.7 g, 108 mmol) and NaBH4 (1.4 g, 36 mmol) were carefully added. The reaction mixture was stirred at room temperature and monitored by thin layer chromatography. 15 minutes after the reaction started, the starting material disappeared. The reaction was quenched with methanol (20 ml), filtered through a Celite filter plate, and washed with methanol (30 ml). The combined filtrate was concentrated and the crude product was purified by flash column chromatography (ethyl acetate / petroleum ether gradient elution) to obtain 4.1 g of compound 8 (R). Yield: 90.1%.

[0159] Synthesis and characterization of compounds 9(1S,2R) and 9(1S,2S)

[0160] Compound 8(S) (4.5 g, 11.5 mmol) and N,N-diisopropylethylamine (DIEA, 57 ml, 34.6 mmol) were dissolved in 15 ml of DMF, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC, 2.3 g, 12.1 mmol) and 1-hydroxybenzotriazole (HOBt, 1.6 g, 12.1 mmol) were added at 0°C. The reaction was stirred for 1 hour, and N,N-dimethyl-N'-ethylethylenediamine (1.7 g, 146 mmol) was added dropwise under an ice bath. The reaction mixture was stirred at room temperature for 5 hours and concentrated to obtain a crude product. The crude product was purified by column chromatography (acetonitrile / water, 2:3-4:1) to obtain 4.9 g of enantiomer. Yield: 87%. A Daicel IC chiral column was used with the column temperature set at 30°C. The mobile phase used was n-hexane / isopropanol (80:20, +2‰ diethylamine) with a flow rate of 1 mL / min. The detection wavelength was 214 nm to perform chiral separation of diastereomers 9(1S, 2R) and 9(1S, 2S).

[0161] N-[((1S)-p-Tolyl)butyl]-2-{2-[(N,N-dimethyl-N′-ethyl)ethylenediamino]-2-oxoethoxy}-3,3-diethyl-(4R)-oxo-azetidinone-1-carboxamide (9(1S,2R))

[0162] de%:96.5%.CD(MeOH)Δε 194 23.467,Δε 213 3.0708,Δε 220 3.4105,Δε 232 1.2951,Δε 241 1.8710. 1H NMR(400MHz,)δ7.15-7.09(m,4H),7.01(t,J=7.3Hz,1H),5.09(d,J=9.1Hz,1H),4.76(dd d,J=13.4,11.9,9.8Hz,2H),4.57(d,J=15.1Hz,1H),3.39(ddd,J=25.7,16.4,7.1Hz,2H), 3.30-3.12(m,2H),2.42(t,J=7.2Hz,H2),2.30(s,H3),2.24(s,H6),1.91-1.66(m,H6),1 .34-1.23(m,2H),1.12(dt,J=24.2,7.1Hz,H3),1.04(t,J=7.5Hz,H3),0.96-0.87(m,H6). 13 CNMR(101MHz, CDCl3)δ173.40,168.25,150.49,139.46,137.01,129.42,126.28,126.26,87.83,68.51,63.39, 57.00,54.12,45.80,44.69,43.31,41.41,39.21,23.88,21.15,21.11,19.48,13.90,12.95,8.91,8.46.ESI-MS m / z:489.3[M+H] + .

[0163] Chiral chromatogram of compound 9 (1S, 2R), 1 H NMR spectrum, 13 C NMR spectrum Figures 3 to 5 shown.

[0164] N-[((1S)-p-Tolyl)butyl]-2-{2-[(N,N-dimethyl-N′-ethyl)ethylenediamino]-2-oxoethoxy}-3,3-diethyl-(4S)-oxo-azetidinone-1-carboxamide (9(1S,2S))

[0165] de%:100%.CD(MeOH)Δε 206 -12.3252,Δε 223 -3.24075,Δε 244 -2.41771,Δε 278 0.128772. 1HNMR(400MHz,)δ7.15(q,J=8.0Hz,4H),7.02-6.96(m,1H),5.16(d,J=10.7Hz,1H), 4.83-4.68(m,2H),4.50(d,J=15.1Hz,1H),3.44-3.30(m,2H),3.25-3.09(m,2H),2. 48-2.35(m,2H),2.31(s,3H),2.20(d,J=21.5Hz,6H),1.90-1.67(m,6H),1.34-1.22 (m,2H),1.10(q,J=7.1Hz,3H),1.00(dt,J=10.2,7.5Hz,6H),0.88(t,J=7.4Hz,3H). 13 CNMR(101MHz, CDCl3)δ173.40,168.25,150.49,139.46,137.01,129.42,126.28,126.26,87.83,68.51,63.39, 57.00,54.12,45.80,44.69,43.31,41.41,39.21,23.88,21.15,21.11,19.48,13.90,12.95,8.91,8.46.ESI-MS m / z:489.3[M+H] + .

[0166] Chiral chromatogram of compound 9 (1S, 2S), 1 H NMR spectrum, 13 C NMR spectrum Figures 6 to 8 shown.

[0167] Synthesis and characterization of compounds 9(1R,2R) and 9(1R,2S)

[0168] Compound 8(R) (4.5 g, 11.5 mmol) and N,N-diisopropylethylamine (DIEA, 57 ml, 34.6 mmol) were dissolved in 15 ml of DMF, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide (EDC, 2.3 g, 12.1 mmol) and 1-hydroxybenzotriazole (HOBt, 1.6 g, 12.1 mmol) were added at 0°C. The reaction mixture was reacted for 1 hour under stirring, and then N,N-dimethyl-N'-ethylethylenediamine (1.7 g, 146 mmol) was gradually added dropwise under ice bath. The reaction mixture was stirred at room temperature for 5 hours and then concentrated to obtain a crude product. The crude product was purified by column chromatography (acetonitrile / water, 2:3-4:1) to obtain 5.1 g of enantiomer. Yield: 90%. A Daicel IC chiral chromatographic column was used with the column temperature set at 30°C; the mobile phase used was n-hexane / isopropanol (80:20, +2‰ diethylamine) with a flow rate of 1 mL / min; the detection wavelength was 214 nm to perform chiral separation of diastereomers 9(1R, 2R) and 9(1R, 2S).

[0169] N-[((1R)-p-Tolyl)butyl]-2-{2-[(N,N-dimethyl-N′-ethyl)ethylenediamino]-2-oxoethoxy}-3,3-diethyl-(4R)-oxo-azetidinone-1-carboxamide (9(1R,2R))

[0170] de%:100%.CD(MeOH)Δε 210 15.2425,Δε 225 3.50748,Δε 243 2.97824,Δε 292 0.008326. 1 HNMR(400MHz,)δ7.15(q,J=8.0Hz,4H),7.02-6.95(m,1H),5.16(d,J=9.9Hz,1H),4.82 -4.67(m,2H),4.50(d,J=15.1Hz,1H),3.49-3.29(m,2H),3.18(dt,J=9.2,7.3Hz,2H),2 .42(t,J=7.1Hz,2H),2.31(s,3H),2.24(s,3H),2.18(s,3H),1.89-1.67(m,6H),1.35-1 .23(m,2H),1.09(q,J=7.1Hz,3H),1.00(dt,J=10.2,7.5Hz,6H),0.88(t,J=7.4Hz,3H). 13C NMR (101MHz, CDCl3) δ173.40,168.28,150.44,139.26,137.01,129.37,126.42,126.39,87.71,68.43,63.35,5 6.95,53.89,45.73,44.64,43.31,41.64,39.17,23.90,21.14,21.10,19.44,13.88,12.94,8.89,8.49.ESI-MS m / z:489.4[M+H] + .

[0171] Chiral chromatogram of compound 9 (1R, 2R), 1 H NMR spectrum, 13 C NMR spectrum Figures 9-11 shown.

[0172] N-[((1R)-p-Tolyl)butyl]-2-{2-[(N,N-dimethyl-N′-ethyl)ethylenediamino]-2-oxoethoxy}-3,3-diethyl-(4S)-oxo-azetidinone-1-carboxamide (9(1R,2S))

[0173] de%:100%.CD(MeOH)Δε 192 -20.2743,Δε 201 -5.39381,Δε 222 -3.0174,Δε 233 -0.90445,Δε 263 -0.09204. 1 H NMR(400MHz,)δ7.14-7.08(m,4H),7.01(t,J=7.2Hz,1H),5.08(d,J=7.7Hz,1H),4.81-4.67(m ,2H),4.56(d,J=15.1Hz,1H),3.38(ddd,J=22.3,15.2,7.2Hz,2H),3.30-3.12(m,2H),2.41(t ,J=7.1Hz,2H),2.29(s,3H),2.23(s,6H),1.96-1.59(m,6H),1.30(dddd,J=18.6,15.0,7.6,4 .6Hz,2H),1.11(dt,J=24.0,7.1Hz,3H),1.03(t,J=7.5Hz,3H),0.91(dt,J=15.9,7.4Hz,6H). 13C NMR (101MHz, CDCl3) δ173.39,168.26,150.49,139.44,137.00,129.43,126.28,87.80,68.47,63.40,56.9 7,54.12,45.69,43.31,41.65,41.18,39.22,23.87,21.14,21.09,19.47,13.85,12.95,8.90,8.44.ESI-MS m / z:489.3[M+H] + .

[0174] Chiral chromatogram of compound 9 (1R, 2S), 1 H NMR spectrum, 13 C NMR spectrum Figures 12-14 shown.

[0175] Example 2 Characterization of absolute configuration using ECD

[0176] With the development of computing power, quantum chemistry has become the basic way to attribute the absolute configuration of compounds. Compared with X-ray single crystal diffraction and Mosher reaction, it has the advantages of no need for compound crystallization and chemical reaction, small amount of compound, and fast configuration determination. Quantum mechanical calculation of chiral spectra has become the most commonly used means of assigning the absolute configuration of organic compounds. When a chiral compound has a suitable chromophore, electronic circular dichroism can become a powerful tool for structural diagnosis. The chiral compounds in this project do not contain chiral secondary alcohol groups or chiral secondary amine groups, so the absolute configuration cannot be determined by Mosher reaction, so ECD is used to determine the configuration.

[0177] method:

[0178] The 3D structure of the final product was drawn using Chem3D, and the preliminary structure optimization was performed using the MMFF94 force field and saved as a mol file for future use. The conformation was searched using CONFLEX software, with the calculation type set to Conformation Search and the Search Limit set to 10. Gaussian 09 / 16 software was used to optimize each conformation using density functional theory (DFT) (B3LYP / 6-311g(d,p)), and the solvent (chloroform) was taken into account to obtain the true low-energy conformation. On this basis, the same unit and method were used for time-dependent density functional theory (TDDFT) calculations. SpecDis software was used to extract the energy of 10 configurations, calculate the Boltzmann coefficient, and Boltzmann average the 10 spectra to obtain the final spectrum. The calculated spectrum was qualitatively and quantitatively compared with the experimental spectrum to assist in determining the absolute configuration of the final product.

[0179] The circular dichroism spectra of 9(1S, 2R) and 9(1S, 2S) synthesized in Example 1 and obtained by chiral separation are as follows: Fig.15 and 16 As shown, there are obvious differences in the circular dichroism spectra of the two, and after ECD calculation, the calculated CD spectrum curve is consistent with the measured curve, indicating that the absolute configuration of the measured compound is consistent with the absolute configuration of the predicted compound, and the diastereoisomers 9(1S,2R) and 9(1S,2S) can be judged and distinguished.

[0180] The circular dichroism spectra of 9(1R, 2R) and 9(1R, 2S) synthesized and obtained by chiral separation in Example 1 are as follows: Fig.17 and 18 As shown, there are obvious differences in the circular dichroism spectra of the two, and after ECD calculation, the calculated CD spectrum curve is consistent with the measured curve, indicating that the absolute configuration of the measured compound is consistent with the absolute configuration of the predicted compound, and the diastereoisomers 9(1R,2R) and 9(1R,2S) can be judged and distinguished.

[0181] Example 3 Calculation NMR Confirmation of Absolute Configuration

[0182] Based on the above ECD calculation, the absolute configuration of the final product has been preliminarily determined. The NMR of non-optical (diastereo) isomers is different, so the calculation of NMR can distinguish 9 (1S, 2R) and 9 (1S, 2S), 9 (1R, 2R) and 9 (1R, 2S) two pairs of diastereoisomers, thereby determining their absolute configuration. Therefore, this project uses the calculation of carbon spectrum / hydrogen spectrum to further verify the absolute configuration of the final product.

[0183] method:

[0184] The 3D structure of the compound was drawn using Chem3D, and the preliminary structure optimization was performed using the MMFF94 force field and saved as a mol file for future use. The conformation was searched using CONFLEX software, with the calculation type set to Conformation Search and the Search Limit set to 10. Gaussian 09 / 16 software was used to perform DFT optimization (mPW1PW91 / 6-311+(2d,p)) for each conformation, and the solvent (chloroform) was taken into account to obtain the true low-energy conformation. On this basis, TDDFT calculations were performed using the same unit and method. The Boltzmann weight Pi was calculated using GaussView 6 to obtain the weight corresponding to each configuration, and the weighted average was calculated based on the weight and the predicted magnetic shielding value of each configuration. The weighted average magnetic shielding value of each carbon atom was subtracted from the magnetic shielding value of TMS (187.4372 for carbon spectrum and 31.7708 for hydrogen spectrum), and the calculated chemical shift of the carbon / hydrogen atom was obtained, as shown in Tables 1 and 2. The calculated and measured values ​​were input into GraphPad Prism for linear regression and the R of the regression equation was calculated. 2 and F and P values ​​of ANOVA.

[0185] Table 1 Calculated carbon spectra of four configurations of compound 9

[0186]

[0187] Note: The calculated magnetic shielding value of C in the reference substance TMS is 187.4372 ppm.

[0188] The Boltzmann weight of each conformation was calculated based on the free energy of the 10 conformations. The Boltzmann weights of the 10 conformations of 9(1S,2R) were 0.1262, 0.1222, 0.1262, 0.1238, 0.1024, 0.1024, 0.1051, 0.1037, 0.0304, and 0.0574, respectively. The calculated carbon spectrum of the compound with this configuration was linearly regressed with the measured carbon spectrum chemical shift, and the equation Y = 0.9624 × X-0.6366, R 2 =0.9993, F = 38235, P < 0.0001. The Boltzmann weights of the 10 conformations of 9 (1S, 2S) are 0.0765, 0.0794, 0.0708, 0.1953, 0.0717, 0.1958, 0.0478, 0.0483, 0.0189, 0.1956 respectively; the calculated carbon spectrum of the compound with this configuration is linearly regressed with the measured carbon spectrum chemical shift, and the equation Y = 0.9647 × X-0.7789, R2 =0.9995, F=48548, P<0.0001. The regression determination coefficient and variance analysis p value suggest that there is a significant linear relationship between the calculated chemical shifts and the measured chemical shifts of diastereomers 9(1S,2R) and 9(1S,2S), and the regression model is statistically significant. The differences in key chemical shifts and regression equations indicate that the calculated carbon spectrum can distinguish diastereomers 9(1S,2R) and 9(1S,2S).

[0189] The Boltzmann weights of the 10 conformations of 9(1R,2R) are 0.0765, 0.0793, 0.0707, 0.1953, 0.0717, 0.1959, 0.0477, 0.0483, 0.0189, and 0.1957, respectively. The calculated carbon spectrum of the compound with this configuration was linearly regressed with the measured carbon spectrum chemical shift, and the equation Y=0.9634*X-0.5704, R 2 =0.9995, F = 46167, P < 0.0001. The Boltzmann weights of the 10 conformations of 9 (1R, 2S) are 0.1262, 0.1222, 0.1262, 0.1238, 0.1024, 0.1023, 0.1051, 0.1037, 0.0304, 0.0575. The calculated carbon spectrum of the compound with this configuration was linearly regressed with the measured carbon spectrum chemical shift, and the equation Y = 0.9637 * X-0.8676, R 2 =0.9993, F=37333, P<0.0001. The regression determination coefficient and the variance analysis p value indicated that there was a significant linear relationship between the calculated chemical shifts and the measured chemical shifts of diastereomers 9(1R,2R) and 9(1R,2S), and the regression model was statistically significant. The differences in key chemical shifts and regression equations indicated that the calculated carbon spectrum could distinguish diastereomers 9(1R,2R) and 9(1R,2S).

[0190] Table 2 Calculated hydrogen spectra of four configurations of compound 9

[0191]

[0192] Note: The calculated magnetic shielding value of H in the reference substance TMS is 31.7708 ppm.

[0193] The linear fitting equations of the calculated chemical shift and measured chemical shift of diastereomers 9(1S,2R) and 9(1S,2S) were Y=0.9299*X+0.1783 and Y=0.9122*X+0.1556, respectively. The regression determination coefficients were 0.9894 and 0.9959, respectively. The p values ​​of variance analysis were all <0.0001, indicating that there was a significant linear relationship between the calculated chemical shift of the independent variable and the measured chemical shift of the dependent variable, and the regression model was statistically significant. The differences in key chemical shifts and regression equations indicate that the calculated hydrogen spectrum can distinguish diastereomers 9(1S,2R) and 9(1S,2S).

[0194] The linear fitting equations of the calculated chemical shift and measured chemical shift of diastereomers 9(1R,2R) and 9(1R,2S) were Y=0.9139*X+0.1461 and Y=0.9272*X+0.1802, respectively, and the regression determination coefficients were 0.9956 and 0.9898, respectively. The p values ​​of variance analysis were all <0.0001, indicating that there was a significant linear relationship between the calculated chemical shift of the independent variable and the measured chemical shift of the dependent variable, and the regression model was statistically significant. The differences in key chemical shifts and regression equations indicate that the calculated hydrogen spectrum can distinguish diastereomers 9(1R,2R) and 9(1R,2S).

[0195] Example 4 Confirmation of absolute configuration based on DP4+ analysis

[0196] In order to further confirm the above conclusions and enhance the persuasiveness, the present application also conducted DP4+ analysis. DP4 analysis is particularly effective for the confirmation of diastereoisomer configurations because it not only predicts the relative stereochemistry and other changes of the molecule. It also uses Bayes' theorem to give the probability that each candidate molecule is the correct molecule. DP4 has become a powerful tool for stereochemical structure interpretation.

[0197] method:

[0198] Conformation searches were performed using CONFLEX as described above, NMR GIAO calculations were performed at the mPW1PW91 / 6-311+(2d,p) / DCM level of theory, and the Boltzmann weights Pi were calculated using GaussView 6. All Boltzmann average magnetic shielding values ​​were calculated for each compound. The DP4+ probability calculation template (sarotti-NMR.weebly.com) prepared by Ariel M. Sarotti team (J.Org.Chem.2015,80,12526-12534) was used. The "mPW1PW91" functional was selected as "Function", "PCM (dichloromethane)" was selected as "Solvent", and "6-311+G(d,p)" was selected as "Basis Set". The measured chemical shift and the magnetic shielding value obtained by the Boltzmann weighted average were input in area B, and the SP2 hybridized atoms C4, C2", C5, C1', C4', C2', C3', C5', C6' and H2', H3', H5' and H6' were marked as "X". The table automatically performs GIAO NMR calculations and displays the probabilities of scaled DP4 (sDP4+), unscaled DP4 (uDP4+) and improved DP4+ in the "DetailedResults" worksheet.

[0199] The results are shown in Tables 3-4.

[0200]

[0201] Table 3 Assignment of absolute configurations of diastereoisomers 9(1R,2R) and 9(1R,2S) based on DP4+ probability calculation

[0202]

[0203]

[0204] Theoretical level: mPW1PW91 / 6-311+G(d,p); Solvent: dichloromethane.

[0205] It can be seen that the probability of the configuration of the hydrogen spectrum and carbon spectrum of compound 9(1RP2) being 9(1R,2R) calculated using only the scaled shift (sDP4+) method, i.e., DP4, is 99.89% and 99.96% respectively, with a comprehensive probability of 100.00%; the probability of the configuration of the hydrogen spectrum and carbon spectrum of compound 9(1RP1) being 9(1R,2S) calculated using the DP4 method is 34.78% and 68.62% respectively, with a comprehensive probability of 53.84%. The improved DP4+ method not only considers the scaled chemical shift (sDP4+), but also considers the unscaled chemical shift (uDP4+). The probability of obtaining the configuration 9(1R,2R) from the hydrogen and carbon spectra of compound 9(1RP2) calculated by DP4+ is 99.99% and 100.00% respectively, and the overall probability is 100.00%; the probability of obtaining the configuration 9(1R,2S) from the hydrogen and carbon spectra of compound 9(1RP1) calculated by DP4+ is 89.90% and 98.65% respectively, and the overall probability is 99.85%. Therefore, the chiral configuration of fragment P2 is R type, and the chiral configuration of fragment P1 is S type, that is, the configuration of the final product 9(1RP2) is 9(1R,2R), and the configuration of the final product 9(1RP1) is 9(1R,2S).

[0206]

[0207] Table 4 Assignment of absolute configurations of diastereoisomers 9(1S2R) and 9(1S2S) based on DP4+ probability calculation

[0208]

[0209]

[0210] Theoretical level: mPW1PW91 / 6-311+G(d,p); Solvent: dichloromethane.

[0211] It can be seen that the probability of the configuration of compound 9(1SP2) being 9(1S,2R) calculated by DP4 method is 31.62% and 88.43% respectively, and the overall probability is 77.95%; the probability of the configuration of compound 9(1SP1) being 9(1S,2S) calculated by DP4 method is 99.93% and 99.99% respectively, and the overall probability is 100.00%. The probability of the configuration of compound 9(1SP2) being 9(1S,2R) calculated by improved DP4+ method is 93.09% and 99.76% respectively, and the overall probability is 99.98%; the probability of the configuration of compound 9(1SP1) being 9(1S,2S) calculated by DP4+ is 99.98% and 100.00% respectively, and the overall probability is 100.00%. Therefore, the chiral configuration of fragment P2 is R-type, and the chiral configuration of fragment P1 is S-type, which is consistent with the above conclusion, that is, the configuration of the final product 9(1SP2) is 9(1S,2R), and the configuration of the final product 9(1SP1) is 9(1S,2S).

[0212] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0213] The above-described embodiments only express several implementation methods of the present application, which is convenient for understanding the technical solution of the present application in detail, but it cannot be understood as limiting the scope of protection of the patent application. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the contents of the attached claims, and the description and drawings may be used to interpret the contents of the claims.

Claims

1. A method for synthesizing compound L635, characterized in that: The steps include: S1: reacting compound 1 with (R)-tert-butylsulfenamide or (S)-tert-butylsulfenamide to prepare compound 2(S) or compound 2(R); S2: subjecting compound 2(S) or compound 2(R) to a Grignard reaction with n-propylmagnesium chloride to prepare compound 3(1R, 2S) or compound 3(1S, 2R); S3: subjecting compound 3(1R, 2S) or compound 3(1S, 2R) to a deprotection reaction in the presence of an acid to prepare compound 4(R) or compound 4(S); S4: Compound 4(R) or Compound 4(S) is subjected to coupling reaction with Compound 6 via N,N'-carbonyldiimidazole in the presence of an organic base to prepare Compound 7(R) or Compound 7(S); S5: subjecting compound 7(S) or compound 7(R) to a deprotection reaction to prepare compound 8(S) or compound 8(R); S6: subjecting compound 8(S) or compound 8(R) to a condensation reaction with N,N-dimethyl-N'-ethylethylenediamine in the presence of an organic base and a condensing agent to prepare compound 9(S) or compound 9(R); S7: chiral separation of compound 9(S) to prepare compound 9(1S, 2R) and compound 9(1S, 2S), or chiral separation of compound 9(R) to prepare compound 9(1R, 2R) and compound 9(1R, 2S); the chiral separation is performed by chromatography, and the mobile phase used in the chromatography is n-hexane and isopropanol in a volume ratio of (75-90):(25-10), which contains diethylamine in an amount of 1.5‰ to 2.5‰ of the total volume of the n-hexane and isopropanol.

2. The method for synthesizing compound L635 according to claim 1, characterized in that: The reaction in step S1 is carried out in the presence of Cs2CO3; and / or, The reaction temperature is 45°C to 60°C, and the reaction time is 10h to 20h.

3. The method for synthesizing the compound L635 according to claim 1, characterized in that: In the Grignard reaction in step S2, the n-propylmagnesium chloride is added at -5 to 5°C and then reacted for 2h to 6h.

4. The method for synthesizing compound L635 according to claim 1, characterized in that: The deprotection reaction in step S3 is carried out by adding an acid at -5 to 5°C and then reacting at room temperature for 1 to 3 hours; and / or The method also includes adding L-tartaric acid or D-tartaric acid to compound 4(R) or compound 4(S) obtained by the deprotection reaction and stirring for 6 hours to 12 hours at room temperature, collecting the product and recrystallizing it with isopropanol.

5. The method for synthesizing the compound L635 according to any one of claims 1 to 4, characterized in that: The organic base in step S4 is N,N-diisopropylethylamine or triethylamine; and / or The coupling reaction was carried out under reflux for 20 to 30 hours.

6. The method for synthesizing the compound L635 according to any one of claims 1 to 4, characterized in that: The deprotection reaction in step S5 is carried out in the presence of Pd / C and hydrogen, the reaction temperature is room temperature, and the reaction time is 15h to 22h; or The deprotection reaction in step S5 is carried out in the presence of NiCl2·6H2O and NaBH4, at room temperature, for 10 min to 20 min.

7. The method for synthesizing the compound L635 according to any one of claims 1 to 4, characterized in that: The organic base in step S6 is N,N-diisopropylethylamine or triethylamine; and / or The condensing agent is 1-hydroxybenzotriazole and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide; and / or The condensation reaction is carried out at room temperature and the reaction time is 3h to 15h.

8. The method for synthesizing the compound L635 according to any one of claims 1 to 4, characterized in that: The synthesis method of compound 6 in step S4 comprises the following steps: Compound 5 is mixed with benzyl glycolate, sodium benzenesulfonate, tetraethylammonium p-toluenesulfonate and a solvent, and an electrode is immersed in the obtained mixed solution to carry out an electrochemical reaction, thereby preparing compound 6.

9. The method for synthesizing compound L635 according to claim 8, characterized in that: The electrochemical reaction is carried out at a temperature of 5°C to 25°C and a constant current of 0.4A to 1A.

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