Synthesis of formoterol

Abstract

The application provides a synthesis method of formoterol, and relates to the technical field of pharmaceutical chemical synthesis. The synthesis method of formoterol provided by the application reduces metal catalysts and hydrogenation deprotection steps, and considers that some substrates have poor thermal stability, so that the use of complex and harsh experimental conditions is avoided. The synthesis method is simple, efficient, low in cost, and environment-friendly, and provides technical support for green synthesis of formoterol.

Description

Technical Field

[0001] This invention relates to the field of pharmaceutical and chemical synthesis technology, and in particular to a method for synthesizing formoterol. Background Technology

[0002] Formoterol, a long-acting selective β2-adrenergic receptor agonist, is a first-line drug for treating dyspnea caused by airway obstructive diseases such as bronchial asthma. Currently, existing synthetic technologies mainly face the following bottlenecks: 1. Traditional Chemical Methods: Reported synthetic routes for formoterol typically utilize benzyloxy-substituted benzene ring intermediates, but all require palladium-on-carbon catalytic hydrogenation to remove protecting groups, and the catalyst is prone to deactivation. These routes also include a one-step nitro-to-amino reduction reaction, which, although often using an iron powder and hydrochloric acid system for high-temperature reactions, suffers from poor thermal stability in some substrates, affecting the reaction's progress.

[0003] 2. Advantages of the chemical-enzymatic method: The chemical-enzymatic method is expected to break through the bottlenecks of the traditional chemical method mentioned above, combining the advantages of chemical synthesis and biocatalysis, and showing unique potential in terms of yield, chiral selectivity, reaction time, substrate concentration and cost control.

[0004] In view of this, the present invention is hereby proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for synthesizing formoterol to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the following technical solution is adopted: In a first aspect, the present invention provides a method for synthesizing formoterol, comprising the following steps: Will and The reaction produces, under the catalysis of a reducing agent or imine reductase (IRED), ; will generate Nitro reduction reaction produces ; will generate Formylation reaction produces .

[0007] As a further technical solution, the reducing agent includes sodium triacetyloxyborohydride; The amino acid sequence of the imine reductase is shown in SEQ ID NO.1.

[0008] As a further technical solution, the aforementioned It undergoes a nitro reduction reaction with B2(OH)4 to produce .

[0009] As a further technical solution, the aforementioned It undergoes a formylation reaction with mixed acid anhydrides to produce The mixed anhydride is formic acid and acetic anhydride in a molar ratio of 1.1:1.

[0010] As a further technical solution, the aforementioned The synthesis method includes the following steps: a. will Nitroation reaction produces ; b. The generated It undergoes a reduction reaction with sodium borohydride to produce ; c. The generated Introducing amino groups ; d. The generated After protecting the amino group with Boc, the methyl group is removed to produce... .

[0011] As a further technical solution, in step a, tetramethylammonium nitrate and trifluoromethanesulfonic anhydride are mixed in a solvent, and after the reaction, they are combined with... Mixed and nitrated to produce .

[0012] As a further technical solution, in step c, the generated Methanol and ammonia are added sequentially, and after an amination reaction, the product is generated. .

[0013] As a further technical solution, in step d, The product is reacted with Boc2O, and then mixed with BBr3 to remove the methyl group, yielding... .

[0014] As a further technical solution, the aforementioned The synthesis method includes the following steps: Will and Mix, then in a mutant of transaldolase (ObiH) and tryptophan decarboxylase (RgnTDC) NMY ) under the catalysis of ; The amino acid sequence of the mutant tryptophan decarboxylase is shown in SEQ ID NO.2.

[0015] As a further technical solution, the amino acid sequence of the transaldolase is shown in SEQ ID NO.3.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The method for synthesizing formoterol provided by this invention reduces the use of metal catalysts and hydrogenation deprotection steps, and avoids the use of complex and harsh experimental conditions. This synthesis method is simple, efficient, low-cost, and environmentally friendly, providing technical support for the green synthesis of formoterol. Detailed Implementation

[0017] The embodiments and examples of the present invention will be described in detail below. However, those skilled in the art will understand that the following embodiments and examples are for illustrative purposes only and should not be considered as limiting the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0018] In a first aspect, the present invention provides a method for synthesizing formoterol, comprising the following steps: Will and The reaction produces, catalyzed by a reducing agent or imine reductase, ; will generate Nitro reduction reaction produces ; will generate Formylation reaction produces .

[0019] The method for synthesizing formoterol provided by this invention reduces the use of metal catalysts and hydrogenation deprotection steps, and avoids the use of complex and harsh experimental conditions. This synthesis method is simple, efficient, low-cost, and environmentally friendly, providing technical support for the green synthesis of formoterol.

[0020] In some alternative implementations, when and When reacting under reducing agent conditions, the reaction can proceed at room temperature; when and During the reaction catalyzed by imine reductase, the reaction system also includes glucose, NADPH, and glucose dehydrogenase. The preferred reaction temperature is 30°C.

[0021] In some alternative embodiments, the reducing agent includes, but is not limited to, sodium triacetyl borohydride, or other reducing agents well known to those skilled in the art; The amino acid sequence of the imine reductase is shown in SEQ ID NO.1: MTKTCVVGAGRMGSAFARALLAEGIETRVWNRSPEKVAPLVAAGAHAPESLAEAVAASDVVIVNVIDYAAADALLRMLAVERALAGKVVVQLTSGSPRQAREAGRWAAERDIAYLDGAIMATPNFIGGAETTILYSGMRQAFERHRDVLRV FGGNGVFVGEDAGHASALDTGLLTQMWGKLFGTLQALAVVRAEGFGLEAYARYMRDFQLVVDAATDDLIARVGEGRWRGDAATLATIEAHYSAFHHLLAIGDEHGLDRALPAALDGLFKAALAAGHAADDFAALMRFIERGGVRHAA (SEQ ID NO.1).

[0022] In some alternative implementations, the It undergoes a nitro reduction reaction with B2(OH)4 to produce This reaction can be carried out at room temperature.

[0023] In some alternative implementations, the It undergoes a formylation reaction with mixed acid anhydrides to produce The mixed anhydrides are formic acid and acetic anhydride in a molar ratio of 1.1:1. The reaction can be carried out at room temperature.

[0024] In some alternative implementations, the The synthesis method includes the following steps: a. will Nitroation reaction produces ; b. The generated It undergoes a reduction reaction with sodium borohydride to produce This reduction reaction can be carried out at room temperature. c. The generated Introducing amino groups ; d. The generated After protecting the amino group with Boc, the methyl group is removed to produce... .

[0025] In some alternative embodiments, in step a, tetramethylammonium nitrate and trifluoromethanesulfonic anhydride are mixed in a solvent, and after reaction, they are combined with... Mixed and nitrated to produce The preferred temperature for this nitration reaction is -40°C.

[0026] In some alternative implementations, in step c, the generated Methanol and ammonia are added sequentially, and after an amination reaction, the product is generated. This reaction can be carried out at room temperature.

[0027] In some alternative implementations, in step d, the following steps are performed: The product is reacted with Boc2O, and then mixed with BBr3 to remove the methyl group, yielding... This reaction can be carried out at room temperature.

[0028] In some alternative implementations, the The synthesis method includes the following steps: Will and Mixed, and then catalyzed by mutants of transaldehyde and tryptophan decarboxylase to produce ; The amino acid sequence of the mutant tryptophan decarboxylase is shown in SEQ ID NO.2: MSQVIKKKRNTFMIGTEYILNSTQLEEAIKSFVHDFCAEKHEIHDQPVVVEAKEHQEDKIKQIKIPEKGRPVNEVVSEMMNEVYRYRGDANHPRFFSFVPGPASSVSWLGDIMTSAYNINAGGSK MAPMVNCIEQEVLKWLAKQVGFTENPGGVFVSGGSMANITALTAARDNKLTDINLHLGTAYISDQTHSSVAKGLRIIGITDSRIRRIPTNSHFQMDTTKLEEAIETDKKSGYIPFVVIGTAGTTNT GSIDPLTEISALCKKHDMWFHIDGAYGASVLLSPKYKSLLTGTGLADSISWDAHKWLFQTYGCAMVLVKDIRNLFHSFHVNPEYLKDLENDIDNVNTYDIGMELTRPARGLKLWLTLQVLGSDLI GSAIEHGFQLAVWAEEALNPKKDWEIVSPAQMAMINFRYAPKDLTKEEQDILNEKISHRILESGYAAIFTTVLNGKTVLRICAIHPEATQEDMQHTIDLLDQYGREIYTEMKKALEHHHHHH (SEQ ID NO.2).

[0029] In some alternative embodiments, the amino acid sequence of the transaldolase is as shown in SEQ ID NO.3: MGSSHHHHHHSSMSNVKQQTAQIVDWLSSTLGKDHQYREDSLSLTANENYPSALVRLTSGSTAGAFYHCSFPFEVPAGEWHFPEPGHMNAIADQVRDLGKTLIGAQAFDWRPNG GSTAEQALMLAACKPGEGFVHFAHRDGGHFALESLAQKMGIEIFHLPVNPTSLLIDVAKLDEMVRRNPHIRIVILDQSFKLRWQPLAEIRSVLPDSCTTLTYDMSHDGGLIMGGV FDSPLSCGADIVHGNTHKTIPGPQKGYIGFKSAQHPLLVDTSLWVCPHLQSNCHAEQLPPMWVAFKEMELFGRDYAAQIVSNAKTLARHLHELGLDVTGESFGFTQTHQVHFAV GDLQKALDLCVNSLHAGGIRSTNIEIPGKPGVHGIRLGVQAMTRRGMKEKDFEVVARFIADLYFKKTEPAKVAQQIKEFLQAFPLAPLAYSFDNYLDEELLAAVYQGAQR (SEQ ID NO.3).

[0030] In some alternative embodiments, the temperature for the reaction catalyzed by the mutants of transaldolase and tryptophan decarboxylase is preferably 35°C.

[0031] The present invention will be further illustrated below with specific embodiments. However, it should be understood that these embodiments are merely for the purpose of more detailed illustration and should not be construed as limiting the present invention in any way.

[0032] Example 1 Chemical Synthesis Scheme of Formoterol 1.1 The specific synthesis route is as follows: Tetramethylammonium nitrate catalysis Nitroation reaction produces Then, sodium borohydride is reduced to produce... Then, amino groups are introduced to generate... Then, using Boc to protect the amino group, the methyl group is removed to produce... Then, sodium triacetylboronide is used for a reducing amination reaction to produce... Then the nitro group is reduced to an amino group to form... Finally, a mixture of acid anhydrides is used to generate the final product. .

[0033] 1.1 Synthesis of 2-bromo-1-(4-methoxy-3-nitrophenyl)ethyl ketone (A)

[0034] Under argon protection, tetramethylammonium nitrate was added to dichloromethane. Trifluoromethanesulfonic anhydride was slowly added dropwise at room temperature with stirring for 1.5 h. After the reaction was complete, the reaction system was transferred to a cryogenic reactor at -50 °C for cooling. α-Bromo-4-methoxyacetophenone dissolved in dichloromethane was slowly added to the system, the temperature was adjusted to -40 °C, and the reaction was continuously stirred for 16 h. After the reaction was completed by TLC monitoring, the reaction was quenched with saturated sodium bicarbonate solution, and the organic phase was separated. The aqueous phase was extracted with dichloromethane, and the organic phases were combined. The organic phase was washed with laboratory water and collected, then dried over anhydrous sodium sulfate. The crude product was purified by silica gel column chromatography with a final yield of 96.5% to give a yellow solid product A—2-bromo-1-(4-methoxy-3-nitrophenyl)acetophenone.

[0035] 1.2 Synthesis of 2-(4-methoxy-3-nitrophenyl)ethylene oxide (B)

[0036] Compound A was dissolved in anhydrous ethanol by stirring. The reaction mixture was placed in an ice bath at 0°C, and an anhydrous ethanol solution of sodium borohydride was slowly added with stirring. After the addition was complete, the ice bath was removed, and the reaction mixture was placed at room temperature and stirred for another 2 hours. The reaction progress was monitored using TLC. After the reaction was complete, an appropriate amount of water was added to quench the reaction until no bubbles were generated and the solution became clear. The reaction solution was first extracted with dichloromethane, and the organic phase was collected. The aqueous phase was then extracted three more times with dichloromethane. The organic phases were combined and dried over anhydrous sodium sulfate. The solution was purified by silica gel column chromatography in 74% yield to give a pale yellow solid product B—2-(4-methoxy-3-nitrophenyl)ethylene oxide.

[0037] 1.3 Synthesis of 2-amino-1-(4-methoxy-3-nitrophenyl)ethanol (C)

[0038] Methanol and ammonia were added sequentially to compound B, and the mixture was stirred at room temperature for 5 h. The reaction was monitored by TLC. After the reaction was completed, the ammonia was first removed by rotary evaporation, followed by three extractions with an appropriate amount of dichloromethane. The organic phases were combined and dried over anhydrous sodium sulfate. The crude product was purified by silica gel column chromatography with a final yield of 58.8% to give the reddish-brown solid product C—2-amino-1-(4-methoxy-3-nitrophenyl)ethanol.

[0039] 1.4 Synthesis of 4-(2-amino-1-hydroxyethyl)-2-nitrophenol (D)

[0040] Compound C was dissolved in methanol with stirring. While stirring, a Boc₂O solution dissolved in methanol was slowly added. After the addition was complete, the reaction was stirred for 2 h. The solvent was evaporated, and the resulting compound was completely dissolved in ethyl acetate. The solution was washed twice with 1 N hydrochloric acid and twice with saturated sodium chloride solution. The organic phase was collected, dried over anhydrous sodium sulfate, and evaporated to dryness to obtain a crude intermediate. This crude intermediate was directly dissolved in dichloromethane and transferred to a -20°C cryogenic reactor. A 1 M BBr₃ solution in dichloromethane was slowly added with stirring. After the addition was complete, the temperature was restored to room temperature, and the reaction was continued for 2 h. The reaction was monitored by TLC. After the reaction was complete, the reaction flask was placed in an ice bath at 0°C, and methanol was slowly added to quench the reaction until the solution became clear. The crude product was purified by silica gel column chromatography with a final yield of 92.4%, yielding a yellow solid product D—4-(2-amino-1-hydroxyethyl)-2-nitrophenol.

[0041] Synthesis of 1,5-4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]-2-nitrophenol (E)

[0042] Compound D was dissolved in 1,2-dichloroethane under stirring, and 4-methoxyphenylacetone was slowly added. Sodium triacetyloxyborohydride was dissolved in 1,2-dichloroethane, and this solution was added dropwise to the above reaction mixture. The reaction system was cooled in an ice bath at 0°C. After the addition was complete, the ice bath was removed, and the reaction was carried out at room temperature for 24 h. The reaction process was monitored by TLC. After the reaction was complete, the solvent was removed. The resulting compound was dissolved in dichloromethane, and an appropriate amount of saturated sodium carbonate solution was added. The mixture was stirred for 2 h. After mixing and allowing to stand for separation, the lower organic phase was separated. The aqueous phase was extracted with dichloromethane, and the organic phases were combined, washed with water, and dried over anhydrous sodium sulfate. Purification was performed by silica gel column chromatography, with a final yield of 32.8%, to give the orange-yellow solid product E—4-[1-hydroxy-2-({1-(4-methoxyphenyl)propyl-2-yl}amino)ethyl]-2-nitrophenol.

[0043] 1.6 Synthesis of 2-amino-4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]phenol (F)

[0044] 4,4'-Bipyridine was dissolved in N,N-dimethylformamide (DMF) for later use. Compound E was dissolved in DMF, and under stirring, B2(OH)4 and the prepared DMF solution were rapidly added to the reaction system, and the reaction was continued at room temperature for 10 min. The reaction progress was monitored by TLC, and the reaction was quenched with water after the reaction was complete. The reaction mixture was then extracted with ethyl acetate, the organic phases were combined, and washed twice with saturated sodium chloride solution. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The product was purified by silica gel column chromatography in a final yield of 44% to give a gray-green powder product F—2-amino-4-[1-hydroxy-2-({1-(4-methoxyphenyl)propyl-2-yl}amino)ethyl]phenol.

[0045] 1.7 Synthesis of N-[2-hydroxy-5-(1-hydroxy-2-{[1-(4-methoxyphenyl)propyl-2-yl]amino}ethyl)phenyl]formamide (G)

[0046] Formic acid and acetic anhydride were mixed at a molar ratio of 1.1:1 and stirred at 55°C for 2.5 h to prepare a mixed anhydride system for later use. Substrate F was placed in a dry double-necked round-bottom flask and dissolved in anhydrous tetrahydrofuran under argon protection. The prepared mixed anhydride was slowly added dropwise to the reaction solution under ice bath conditions at 0°C. After the addition was complete, the ice bath was removed, and the reaction continued at room temperature for 3 h. The reaction progress was monitored by TLC. After the reaction was complete, the reaction was quenched with saturated sodium bicarbonate solution. The mixture was extracted three times with ethyl acetate, and the organic phases were combined and washed three times with saturated sodium chloride solution. The obtained organic phase was dried over anhydrous sodium sulfate and purified by silica gel column chromatography with a final yield of 59% to give a white solid final product G—N-[2-hydroxy-5-(1-hydroxy-2-{[1-(4-methoxyphenyl)propyl-2-yl]amino}ethyl)phenyl]formamide.

[0047] Example 2 Chemical-enzymatic synthesis scheme 1.1 Complete chemical-enzymatic synthetic route:

[0048] 1.1 Two-enzyme cascade reaction system: one-step generation of the key intermediate of formoterol, (R)-4-(1-hydroxy-2-aminoethyl)-2-nitrophenol

[0049] 10 mM 4-hydroxy-3-nitrobenzaldehyde was dissolved in a mixed solvent of 0.3 mL methanol and 0.2 mL dimethyl sulfoxide (DMSO); 50 mM DL-threonine was dissolved in 0.5 mL of 50 mM potassium phosphate buffer (KPi, pH 8.0). Recombinant expression of ObiH and RgnTDC was performed. NMY The protein-producing strain was *E. coli* BL21(DE3). After IPTG induction culture in TB liquid medium containing kanamycin and ampicillin, the bacterial cells were collected, treated with lysozyme, and sonicated. The supernatant was then collected by centrifugation to obtain the protein containing ObiH and RgnTDC. NMY Cell-free extract. ObiH (sequence shown in SEQ ID NO.3) and RgnTDC were added to the system. NMY (Sequence shown in SEQ ID NO.2) Cell-free extract (final concentration 50 g / L) and 400 μM pyridoxal phosphate (PLP) solution (24 μL) were added, and the total volume of the reaction system was brought to 10 mL with potassium phosphate buffer of the same pH. The reaction was carried out at 35 °C for 21 h. After the reaction, each reaction was extracted three times with ethyl acetate. Acetonitrile was added to the aqueous phase after extraction, and the mixture was vortexed and poured into a vacuum funnel with diatomaceous earth. All aqueous phases were collected, evaporated to dryness, and purified.

[0050] High-performance liquid chromatography (HPLC) conditions: HPLC analysis was performed using an Agilent 1260 Infinity II system equipped with an Extend-C18 column (4.6 mm × 250 mm, 5 μm). Analytical conditions: flow rate 0.5 mL / min, column temperature 30 ℃, injection volume 5 μL, system pressure limit 300 bar. The mobile phase was methanol / water (containing 0.1% v / v triethylamine), with the phase ratio maintained at 5:95. The total run time for this isocratic elution program was 20 min.

[0051] 1.2 Imine reductase (IRED) catalytic reaction system: Synthesis of formoterol key intermediate 4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]-2-nitrophenol.

[0052]

[0053] The standard reaction system for screening enzyme activity using imine reductase IR-48 (sequence shown in SEQ ID NO.1) is as follows: 10 mM ketone substrate, 20 mM amine substrate, 30 mM glucose, 0.3 mL methanol, 0.3 mL DMSO, 1 mg NADPH, 0.5 mg glucose dehydrogenase (GDH), and recombinant *E. coli* BL21(DE3) expressing IRED protein as the producing strain. After IPTG induction culture in LB broth containing kanamycin, the bacterial cells were collected, sonicated, and the supernatant was collected by centrifugation to obtain a cell-free extract of IRED (100 g / L). The remaining volume was replenished to 10 mL with the appropriate buffer. The reaction was carried out at 30 °C for 24 h. After the reaction, 10 mL of ethyl acetate was added for extraction. This process was repeated three times. The organic phases were combined, dried over anhydrous Na2SO4, and concentrated under reduced pressure using a rotary evaporator. The final product was detected by high-performance liquid chromatography (HPLC). All experiments were independently repeated three times.

[0054] High-performance liquid chromatography (HPLC) conditions: HPLC analysis was performed using an Agilent 1260 Infinity II system with an Extend-C18 column (4.6 mm × 250 mm, 5 μm). Analytical conditions: flow rate 0.5 mL / min, column temperature 30℃, injection volume 5 μL, system pressure limit 300 bar. The mobile phase was methanol-0.1% phosphoric acid aqueous solution, with the following gradient elution program: 0–10 min, methanol increased from 5% to 50%; 10–15 min, increased to 80%; 15–25 min, increased to 95% and held; 25–30 min, decreased to 5%, equilibrated for 5 min. The total run time for this gradient elution program was 30 min.

[0055] Formoterol was then synthesized using 4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]-2-nitrophenol, following the same synthesis steps as in Example 1.

[0056] The NMR characterization results of each reaction product in Examples 1 and 2 above are as follows: The NMR characterization of 2-bromo-1-(4-methoxy-3-nitrophenyl)ethyl ketone (A) is as follows: 1H NMR (400 MHz, DMSO-d6) δ 8.56 – 8.42 (m, 1H), 8.29 (dd, J = 8.9, 2.3 Hz, 1H), 7.56 (dd, J = 27.5, 9.1 Hz, 1H), 4.94 (s, 2H), 4.07 (d, J = 17.3Hz, 3H). The NMR characterization of 2-(4-methoxy-3-nitrophenyl)ethylene oxide (B) is as follows: 1H NMR (400 MHz, DMSO-d6) δ 7.79 (d, J = 2.2 Hz, 1H), 7.58 (dd, J =8.7, 2.3 Hz, 1H), 7.35 (d, J = 8.7 Hz, 1H), 3.99 (dd, J = 4.2, 2.6 Hz, 1H), 3.92 (s, 3H), 3.12 (dd, J = 5.2, 4.1 Hz, 1H), 2.91 (dd, J = 5.1, 2.6 Hz, 1H). The NMR characterization of 2-amino-1-(4-methoxy-3-nitrophenyl)ethanol (C) is as follows: 1H NMR (400 MHz, DMSO-d6) δ 7.81 (d, J = 2.2 Hz, 1H), 7.60 (dd, J =8.7, 2.2 Hz, 1H), 7.32 (d, J = 8.7 Hz, 1H), 4.49 (dd, J = 7.2, 4.5 Hz, 1H), 3.91 (s, 3H), 2.74 – 2.56 (m, 2H). The NMR characterization of 4-(2-amino-1-hydroxyethyl)-2-nitrophenol (D) is as follows: 1H NMR (400 MHz, Methanol-d4) δ 8.17 (d, J = 2.2 Hz, 1H), 7.71 (dd, J= 8.6, 2.2 Hz, 1H), 7.19 (d, J = 8.6 Hz, 1H), 4.97 (dd, J = 9.4, 3.3 Hz, 1H), 3.23 (dd, J = 12.8, 3.4 Hz, 1H), 3.03 (dd, J = 12.8, 9.4 Hz, 1H). The NMR characterization of 4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]-2-nitrophenol (E) is as follows: 1H NMR (400 MHz, DMSO-d6) δ 7.79 (t, J = 2.1 Hz, 1H), 7.35 (ddd, J =8.8, 5.2, 2.3 Hz, 1H), 7.14 – 7.03 (m, 2H), 6.94 (dd, J = 8.7, 1.5 Hz, 1H),6.83 (dd, J = 8.4, 5.5 Hz, 2H), 4.67 – 4.58 (m, 1H), 3.79 – 3.64 (m, 4H),2.91 – 2.67 (m, 2H), 2.57 – 2.41 (m, 1H), 0.97 (d, J = 6.3 Hz, 3H). The NMR characterization of 2-amino-4-[1-hydroxy-2-({1-(4-methoxyphenyl)prop-2-yl}amino)ethyl]phenol (F) is as follows: 1H NMR (400 MHz, Methanol-d4) δ 6.66 – 6.58 (m, 1H), 6.57 – 6.49 (m,1H), 6.44 – 6.28 (m, 2H), 6.24 (dd, J = 6.8, 2.1 Hz, 1H), 6.17 (dd, J = 8.1, 6.5 Hz, 1H), 6.06 (ddd, J = 8.1, 4.0, 2.1 Hz, 1H), 4.07 (dt, J = 7.8, 5.3 Hz, 1H), 3.40 – 3.29 (m, 3H), 2.47 – 2.30 (m, 2H), 2.27 – 2.02 (m, 3H), 0.59 (d,J = 6.2 Hz, 3H). The NMR characterization of N-[2-hydroxy-5-(1-hydroxy-2-{[1-(4-methoxyphenyl)propyl-2-yl]amino}ethyl)phenyl]formamide (G) is as follows: 1H NMR (400 MHz, Methanol-d4) δ 8.32 (s, 1H), 8.09 (t, J = 2.7 Hz,1H), 7.28 – 7.13 (m, 3H), 7.06 (s, 0H), 6.96 – 6.85 (m, 3H), 3.77 (s, 4H), 3.53 – 3.40 (m, 1H), 3.26 – 3.06 (m, 2H), 2.70 (ddd, J = 13.4, 9.9, 3.4 Hz, 1H), 1.24 (q, J = 8.4 Hz, 5H), 0.86 (th, J = 6.5, 2.5 Hz, 1H). Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing formoterol, characterized in that, Includes the following steps: Will and The reaction produces, catalyzed by a reducing agent or imine reductase, ; will generate Nitro reduction reaction produces ; will generate Formylation reaction produces .

2. The synthesis method according to claim 1, characterized in that, The reducing agent includes sodium triacetyl borohydride; The amino acid sequence of the imine reductase is shown in SEQ ID NO.

1.

3. The synthesis method according to claim 1, characterized in that, The It undergoes a nitro reduction reaction with B2(OH)4 to produce .

4. The synthesis method according to claim 1, characterized in that, The It undergoes a formylation reaction with mixed acid anhydrides to produce The mixed anhydride is formic acid and acetic anhydride in a molar ratio of 1.1:

1.

5. The synthesis method according to claim 1, characterized in that, The The synthesis method includes the following steps: a. will Nitroation reaction produces ; b. The generated It undergoes a reduction reaction with sodium borohydride to produce ; c. The generated Introducing amino groups ; d. The generated After protecting the amino group with Boc, the methyl group is removed to produce... .

6. The synthesis method according to claim 5, characterized in that, In step a, tetramethylammonium nitrate and trifluoromethanesulfonic anhydride are mixed in a solvent, and after the reaction, they are combined with... Mixed and nitrated to produce .

7. The synthesis method according to claim 5, characterized in that, In step c, the generated Methanol and ammonia are added sequentially, and after an amination reaction, the product is generated. .

8. The synthesis method according to claim 5, characterized in that, In step d, The product is reacted with Boc2O, and then mixed with BBr3 to remove the methyl group, yielding... .

9. The synthesis method according to claim 1, characterized in that, The The synthesis method includes the following steps: Will and Mixed, and then catalyzed by mutants of transaldehyde and tryptophan decarboxylase to produce ; The amino acid sequence of the mutant tryptophan decarboxylase is shown in SEQ ID NO.

2.

10. The synthesis method according to claim 9, characterized in that, The amino acid sequence of the transaldolase is shown in SEQ ID NO.3.

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