Monoalkylcyclopentadiene compounds and methods for preparing same

Abstract

The present disclosure provides a method for the synthesis of mono-alkylated cyclopentadiene structures obtained via fulvene intermediates. In one embodiment, the cyclopentadiene ring is substituted with a trialkylsilyl moiety, which allows for further reaction with certain metal halides to form metal adducts. For example, mono-alkylcyclopentadienes substituted with trimethylsilyl groups can be reacted with TiCl4 to form R * CpTiCl complexes can be provided, where R * is the formula, TIFF2024539770000039.tif23170[where, R 1 and R 2 is as defined herein.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE

[0001] This disclosure relates generally to methods for preparing mono-alkylated cyclopentadiene compounds. [Background technology]

[0002]

[0002] Cyclopentadiene is a useful intermediate for many other useful organic compounds. Certain alkyl-substituted cyclopentadienes are useful as synthetic lubricants. (See, e.g., U.S. Pat. Nos. 5,144,095 and 5,012,022.) Furthermore, the cyclopentadiene structure is found in many of the so-called single-site metallocene catalysts used in the production of polyolefins such as polyethylene and polypropylene (see, e.g., U.S. Pat. No. 7,579,415).

[0003] One inherent difficulty in working with cyclopentadiene is its tendency to dimerize via the Diels-Alder reaction. This dimerization proceeds over several hours at room temperature but can be reversed by heating, sometimes requiring a cracking step. Furthermore, alkylation reactions utilizing cyclopentadiene anion species can result in the formation of di- and tri-alkyl species, which further complicate the synthetic regime by reducing yields and requiring further separation and purification.

[0004]

[0004] Therefore, there is a need for improved methodologies for the monoalkylation of cyclopentadiene structures. Summary of the Invention

[0005] In summary, the present disclosure provides a methodology for the selective synthesis of mono-alkylated cyclopentadiene structures obtained via fulvene intermediates. In one embodiment, the cyclopentadiene ring is substituted with a trialkylsilyl moiety, which allows for further reaction with certain metal halides to form metal complexes. For example, a mono-alkylcyclopentadiene substituted with a trimethylsilyl group can be reacted with TiCl4 to form R * CpTiCl complex can be obtained, where R * is the formula, TIFF0007772941000001.tif21170[where, R 1 and R 2 is defined as follows: In this highly selective process, the resulting product is mono-alkylated, with no di-alkylated products detected by gas chromatography or NMR. In this regard, the method of the present invention is particularly useful for preparing (mono)isopropyl-substituted cyclopentadienes. DETAILED DESCRIPTION OF THE INVENTION

[0006]

[0006] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term "or" is generally used in its sense including "and / or" unless the content clearly dictates otherwise.

[0007]

[0007] The term "about" generally refers to a range of numbers considered equivalent to a stated value (e.g., having the same function or result). In many instances, the term "about" may include numbers that are rounded to the nearest significant figure.

[0008] Numerical ranges expressed using endpoints include all numbers subsumed within that range (eg, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5).

[0009] In one aspect, the present disclosure provides a compound of formula (I): TIFF0007772941000002.tif25170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl, formula, TIFF0007772941000003.tif46170 with a protic reagent.

[0010] In one embodiment of this aspect, the protic reagent is water, optionally containing an acid such as HCl (hydrochloric acid). In another embodiment, the protic reagent is an alcohol or a polyol, optionally containing an acid. In another embodiment, R 1 and R 2 is methyl. In other embodiments, the alcohol is selected from C1 to C8 alcohols.

[0011] In another aspect, the present disclosure provides a compound of formula (I): TIFF0007772941000004.tif25170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl, Cyclopentadiene is reacted with a compound of the formula TIFF0007772941000005.tif16170 in the presence of a base, thereby producing a compound of formula: TIFF0007772941000006.tif35170, which is then treated with a dialkyl magnesium compound, thereby forming a compound of formula TIFF0007772941000007.tif46170, which is then treated with a protic reagent to provide a compound of formula (I).

[0012] Generally, the starting material, fulvene, is reacted with cyclopentadiene in the presence of a base such as pyrrolidone or an alkali metal hydroxide to form a compound of formula R 1 -C(O)-R 2 Magnesocene (2), shown in Figure 1, can then be formed by reacting the fulvene intermediate (1) with a dialkylmagnesium compound, such as Mg(CHCHCHCH) in a non-coordinating solvent, such as hexane. In this regard, suitable dialkylmagnesium compounds include those with alkyl groups capable of β-hydride elimination; examples include Mg(C-C alkyl), Mg(C-C alkyl), or Mg(C-C alkyl). Scheme 1, below, outlines a general synthetic scheme for quenching magnesocene (2) with a protic reagent or trialkylsilyl halide (e.g., trimethylsilyl chloride) to yield the desired compound.

[0013] Scheme 1: General synthetic scheme for the synthesis of monoalkylcyclopentadienes TIFF0007772941000008.tif65170

[0014]

[0014] Thus, in a further aspect, the present disclosure provides a compound of formula (II): TIFF0007772941000009.tif36170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl; R 3 is a group of the formula (C1-C4 alkyl)3Si-] 1. A method for preparing a compound of formula (I), comprising: Cyclopentadiene is reacted with a compound of the formula TIFF0007772941000010.tif18170 in the presence of a base, thereby producing a compound of formula: TIFF0007772941000011.tif35170, which is then treated with a dialkyl magnesium compound, thereby forming a compound of formula TIFF0007772941000012.tif46170 compound is formed, which is then treated with a compound of formula (C1-C4 alkyl)3Si-X, wherein X is halo, to provide a compound of formula (II).

[0015] In certain embodiments, R 1 and R 2 is selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, n-pentyl, isopentyl, sec-pentyl, n-hexyl, isohexyl, sec-hexyl, n-heptyl, isoheptyl, sec-heptyl, n-octyl, isooctyl, and sec-octyl. 1 and R 2 is methyl. In one embodiment, R 3 is trimethylsilyl. In one embodiment, X is selected from chloro, bromo, or iodo, and in another embodiment, X is chloro.

[0016] The compounds of formula (I) and formula (II) are useful as intermediates in the synthesis of metallocene catalysts. In addition, the compounds of formula (II) are useful for the preparation of Group IV, V, VI and metal-substituted compounds in the plus four oxidation state by reaction with the corresponding metal halides. For example, compounds of formula (II) [wherein R 3 is trimethylsilyl] reacts with TiCl4 to give R * The CpTiCl3 complex can be obtained.

[0017]

[0017] In the present disclosure, processes beginning with substituted fulvene starting materials allow for the synthesis of only mono-alkyl-substituted compounds, as opposed to the formation of multiply alkylated cyclopentadienyl species that can occur in conventional alkylation reaction approaches. The products can be deprotonated with an initial metal-Cp complex (i.e., anionic cyclopentadiene) prior to secondary alkylation, e.g., with an alkyl bromide. In the latter case, the level of multiply alkylated species can range from 0.5 to 5 weight percent. Advantageously, the disclosed processes provide mono-alkylated species free of detectable levels of multiply alkylated species by gas chromatography (e.g., GC and GC-MS) or NMR. Thus, in further embodiments, the disclosed processes provide products having less than 0.5 weight percent, less than 0.3 weight percent, or less than 0.1 weight percent multiply alkylated species as measured by gas chromatography.

[0018] Furthermore, in view of the substituted fulvene approach outlined herein, the present disclosure further advantageously provides products of formulas (I) and (II) that are devoid of dicyclopentadiene and mixed dicyclopentadiene species.

[0019]

[0019] The compounds of formulas (I) and (II), i.e., monoalkyl-substituted cyclopentadienes, are also useful as intermediates in the synthesis of metallocene catalysts, which are useful in the synthesis of various polyolefins, or as intermediates for precursors useful in atomic layer deposition (ALD) and chemical vapor deposition (CVD).

[0020]

[0020] Example -

[0021] i PrCp and i Synthesis procedure of PrCp-TMS

[0022] Step 1: Synthesis of 6,6-dimethylfulvene (1e)

[0023] Acetone (1000 g, 17.2 mol), methanol (3 L, 2360 g), and cyclopentadiene ("Cp") (1138 g, 17.2 mmol) were added to a flask. The resulting mixture was cooled to -10°C. Pyrrolidine (100 g, 1.4 mol) was added portionwise while maintaining the temperature at <0°C. After the addition of pyrrolidine was complete, the resulting mixture was stirred at -10°C to 0°C for 2 hours. The reaction mixture was allowed to warm to room temperature and stirred overnight. The resulting mixture was cooled to 0-5°C, and 4% aqueous acetic acid (3000 mL) was added. The resulting biphasic mixture was allowed to settle, and the aqueous layer was discarded. The organic phase was washed with brine, and residual solvent was removed under vacuum. 6,6-dimethylfulvene (1740 g) was obtained. 1 The product was obtained in 95% yield and 96% purity by H-NMR and GC. Further purification by distillation revealed 1 It was obtained in 90% yield and 99% purity by H-NMR and GC.

[0021]

[0024] Compounds 1a-1f were prepared by the same procedure using the appropriate aldehyde / ketone.

[0022]

[0025] Step 2: Synthesis of bis[1-isopropyl-2,4-cyclopentadien-1-yl]magnesium (2e)

[0026] 6,6-Dimethylfulvene (21.2 g, 0.2 mol) and hexane (50 mL) were added to a flask under nitrogen. 1 M di-n-butylmagnesium (100 mL, 0.1 mol) in heptane was added dropwise while maintaining the temperature at <50°C. After the addition of di-n-butylmagnesium, the resulting solution was stirred overnight at room temperature. Complete removal of volatiles under vacuum afforded bis[1-isopropyl-2,4-cyclopentadien-1-yl]magnesium (23.2 g). 1 It was produced in 98.3% yield and 99% purity by H-NMR.

[0023]

[0027] NOTE: n-butyl-sec-butylmagnesium in hexane can be used instead of di-n-butylmagnesium heptane.

[0024]

[0028] Compounds 2a, 2c, 2e and 2f were prepared in a similar manner using the appropriate fulvene.

[0025]

[0029] Step 3A: Synthesis of isopropyl-Cp (3e)

[0030] Bis[1-isopropyl-2,4-cyclopentadien-1-yl]magnesium (10 g) and hexane (100 mL) were added to a flask under nitrogen. The resulting mixture was cooled to 0°C and 0.1 M HCl (25 mL) was added dropwise, maintaining the temperature at <5°C. The resulting mixture was allowed to warm to room temperature. The aqueous layer was discarded and the organic layer was dried over anhydrous magnesium sulfate. The resulting mixture was filtered. The hexane was removed under reduced pressure to give isopropylcyclopentadiene (8.3 g, mixture of isomers). 1 It was produced in 91% yield and 98% purity by 1 H-NMR and GC.

[0026]

[0031] Note: Water or alcohol can be used instead of the 0.1 M HCl solution.

[0027]

[0032] Compounds 3a, 3c, 3e and 3f were prepared in a similar manner using the appropriate bis(cyclopentadienyl)magnesium complex.

[0028]

[0033] Step 3B: Synthesis of isopropyltrimethylsilyl-Cp (4e)

[0034] Bis[1-isopropyl-2,4-cyclopentadien-1-yl]magnesium (10 g) and hexane (100 mL) were added to a flask under nitrogen. The resulting mixture was cooled to 0 °C and trimethylsilyl chloride (9.3 g) was added dropwise, maintaining the temperature at <5 °C. The resulting mixture was warmed to room temperature and passed through a silica plug. The hexane was removed under reduced pressure to give isopropyltrimethylsilylcyclopentadiene (13.8 g, mixture of isomers). 1 It was produced in 90% yield and 98% purity by 1 H-NMR.

[0029]

[0035] Compounds 4c, 4e and 4f were prepared in a similar manner using the appropriate bis(cyclopentadienyl)magnesium complex.

[0030]

[0036] Table 1: Overview of alkyl-Cps and alkyl-Cp-TMS materials TIFF0007772941000013.tif79170

[0031]

[0037] Aspects

[0038] In a first aspect, the present disclosure provides a compound of formula (I): TIFF0007772941000014.tif25170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl, comprising a compound of the formula: TIFF0007772941000015.tif46170 with a protic reagent.

[0032]

[0039] In a second aspect, the present disclosure provides the method of the first aspect, wherein the protic reagent is water.

[0033]

[0040] In a third aspect, the present disclosure provides the method of the second aspect, wherein the water further comprises an acid.

[0034]

[0041] In a fourth aspect, the present disclosure provides the method of the first aspect, wherein the protic reagent is an alcohol or a polyol.

[0035]

[0042] In a fifth aspect, the present disclosure provides the method of the fourth aspect, wherein the protic reagent further comprises an acid.

[0036]

[0043] In a sixth aspect, the present disclosure provides a method of any one of the first to fifth aspects, wherein R 1 and R 2 is methyl.

[0037]

[0044] In a seventh aspect, the present disclosure provides the method of the fourth aspect, wherein the alcohol is selected from a C1 to C8 alcohol.

[0038]

[0045] In an eighth aspect, the present disclosure provides the method of any one of the first through seventh aspects, wherein the compound of formula (I) has less than about 0.5 weight percent, less than about 0.3 weight percent, or less than about 0.1 weight percent of multiply alkylated species as measured by gas chromatography.

[0039]

[0046] In a ninth aspect, the present disclosure provides the method of any one of the first to eighth aspects, wherein the compound of formula (I) is devoid of dicyclopentadiene species and mixed dicyclopentadiene species.

[0040]

[0047] In a tenth aspect, the present disclosure provides a compound of formula (I): TIFF0007772941000016.tif25170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl, Cyclopentadiene is reacted with a compound of the formula TIFF0007772941000017.tif16170 in the presence of a base, thereby producing a compound of formula: TIFF0007772941000018.tif36170 compound formation This is then treated with a dialkyl magnesium compound, whereby a compound of the formula: TIFF0007772941000019.tif46170 compound is formed, which is then treated with a protic reagent to provide a compound of formula (I).

[0041]

[0048] In an eleventh aspect, the present disclosure provides the method of the tenth aspect, wherein the protic reagent is water.

[0042]

[0049] In a twelfth aspect, the present disclosure provides the method of the eleventh aspect, wherein the water further comprises an acid.

[0043]

[0050] In a thirteenth aspect, the present disclosure provides the method of the tenth aspect, wherein the protic reagent is an alcohol or a polyol.

[0044]

[0051] In a fourteenth aspect, the present disclosure provides the method of the thirteenth aspect, wherein the alcohol or polyol further comprises an acid.

[0045]

[0052] In a fifteenth aspect, the present disclosure provides a method of any one of the tenth to fourteenth aspects, wherein R 1 and R 2 is methyl.

[0046]

[0053] In a sixteenth aspect, the present disclosure provides the method of the thirteenth or fourteenth aspect, wherein the alcohol is selected from a C1 to C8 alcohol.

[0047]

[0054] In a seventeenth aspect, the present disclosure provides a compound of formula (II): TIFF0007772941000020.tif36170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl; R 3 is a group of formula (C1-C4 alkyl)3Si-, Cyclopentadiene is reacted with a compound of the formula TIFF0007772941000021.tif16170, whereby a compound of formula: TIFF0007772941000022.tif35170 compounds are formed, This is then treated with a dialkyl magnesium compound, whereby a compound of the formula: TIFF0007772941000023.tif46170 compound is formed, which is then treated with a compound of formula (C1-C4 alkyl)3Si-X, wherein X is halo, to provide a compound of formula (II).

[0048]

[0055] In an eighteenth aspect, the present disclosure provides the method of the seventeenth aspect, wherein R 1 and R 2 Each of the is methyl.

[0049]

[0056] In a nineteenth aspect, the present disclosure provides a method of the seventeenth or eighteenth aspect, wherein R 3 is trimethylsilyl.

[0050]

[0057] In a twentieth aspect, the present disclosure provides the method of the seventeenth, eighteenth, or nineteenth aspect, wherein X is chloro.

[0051]

[0058] In a twenty-first aspect, the present disclosure provides the method of any one of the seventeenth to twentieth aspects, wherein the compound of formula (II) has less than about 0.5 weight percent, less than about 0.3 weight percent, or less than about 0.1 weight percent of multiply alkylated species as measured by gas chromatography.

[0052]

[0059] In a twenty-second aspect, the present disclosure provides the method of any one of the seventeenth to twenty-first aspects, wherein the compound of formula (II) is devoid of dicyclopentadiene species and mixed dicyclopentadiene species.

[0053]

[0060] In a twenty-third aspect, the present disclosure provides the method of any one of the seventeenth to twenty-second aspects, further comprising treating the compound of formula (II) with a Group IV, Group V, or Group VI metal halide.

[0054]

[0061] In a twenty-fourth aspect, the present disclosure provides the method of the twenty-third aspect, wherein the metal halide is TiCl4.

[0055]

[0062] In a twenty-fifth aspect, the present disclosure provides a compound of formula (I): TIFF0007772941000024.tif25170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl. wherein the compound of formula (I) has less than about 0.5 percent of multiply alkylated species as determined by gas chromatography.

[0056]

[0063] In a twenty-sixth aspect, the present disclosure provides a compound of the twenty-fifth aspect, wherein R 1 and R 2 is methyl.

[0057]

[0064] In a twenty-seventh aspect, the present disclosure provides the method of the twenty-fifth or twenty-sixth aspect, wherein the compound of formula (I) is devoid of dicyclopentadiene species and mixed dicyclopentadiene species.

[0058]

[0065] In a twenty-eighth aspect, the present disclosure provides a compound of formula (I) as claimed in any one of the twenty-fifth to twenty-seventh aspects, wherein the compound of formula (I) has less than about 0.3 weight percent of multiply alkylated species as measured by gas chromatography.

[0059]

[0066] In a twenty-ninth aspect, the present disclosure provides a compound of formula (I) as claimed in any one of the twenty-fifth to twenty-seventh aspects, wherein the compound of formula (I) has less than about 0.1 weight percent of multiply alkylated species as measured by gas chromatography.

[0060]

[0067] In a thirtieth aspect, the present disclosure provides a compound of formula (II): TIFF0007772941000025.tif36170[where, R 1 and R 2 are independently selected from hydrogen and C1-C8 alkyl; R 3 is a group of the formula (C1-C4 alkyl)3Si-] wherein the compound of formula (II) has less than about 0.5 weight percent of multiply alkylated species as determined by gas chromatography.

[0061]

[0068] In a thirty-first aspect, the present disclosure provides a compound of the thirtieth aspect, wherein R 1 and R 2 is methyl.

[0062]

[0069] In a thirty-second aspect, the present disclosure provides the method of the thirty-first aspect, wherein the compound of formula (II) is devoid of dicyclopentadiene species and mixed dicyclopentadiene species.

[0063]

[0070] In a thirty-third aspect, the present disclosure provides a compound of formula (II) as claimed in any one of the thirty-first to thirty-second aspects, wherein the compound of formula (II) has less than about 0.3 weight percent of multiply alkylated species as measured by gas chromatography.

[0064]

[0071] In a thirty-fourth aspect, the present disclosure provides a compound of formula (II) as claimed in any one of the thirty-first to thirty-second aspects, wherein the compound of formula (II) has less than about 0.1 weight percent of multiply alkylated species as measured by gas chromatography.

[0065]

[0072] While several exemplary embodiments of the present disclosure have been described above, those skilled in the art will readily appreciate that still other embodiments may be made and used within the scope of the claims appended hereto. Numerous advantages of the disclosure set forth in this document have been set forth in the foregoing description. It will be understood, however, that this disclosure is, in many respects, merely illustrative. The scope of the disclosure, of course, is defined in the language in which the appended claims are expressed.

Claims

1. Formula (I): [In the formula, R １ and R ２ is hydrogen and C １ ~C ８ and independently selected from alkyl, formula with water, or an alcohol or polyol.

2. The method of claim 1 , wherein the water further comprises an acid.

3. The method of claim 1, wherein the alcohol or polyol further comprises an acid.

4. R １ and R ２ 4. The method of claim 1, wherein is methyl.

5. Alcohol is C １ ~C ８ 5. The method of claim 4, wherein the alcohol is selected from the group consisting of alcohols.

6. 6. The method of any one of claims 1 to 5, wherein the compound of formula (I) has less than 0.5 weight percent multiply alkylated cyclopentadiene as determined by gas chromatography.

7. 7. The method of any one of claims 1 to 6, wherein the compound of formula (I) is devoid of dicyclopentadiene.

8. Formula (I): [In the formula, R １ and R ２ is hydrogen and C １ ~C ８ and independently selected from alkyl, Cyclopentadiene is reacted with a compound of the formula in the presence of a base, thereby producing a compound of formula forming a compound of This is then treated with a dialkyl magnesium compound, whereby a compound of formula forming a compound of which is then treated with water, or an alcohol or polyol to provide a compound of formula (I).

9. The method of claim 8 , wherein the water further comprises an acid.

10. The method of claim 9 wherein the alcohol or polyol further comprises an acid.

11. R １ and R ２ 11. The method of any one of claims 8 to 10, wherein is methyl.

12. Alcohol is C １ ~C ８ 11. The method according to claim 8 or 10, wherein the alcohol is selected from the group consisting of alcohols.

13. Formula (II): [In the formula, R １ and R ２ is hydrogen and C １ ~C ８ alkyl; R ３ is the formula (C １ ~C ４ alkyl) ３ a method for preparing a compound of formula (I) wherein the compound is a Si— group, Cyclopentadiene is reacted with a compound of the formula and contacting the compound of formula forming a compound of This is then treated with a dialkyl magnesium compound, whereby a compound of formula forming a compound of This is then converted into the formula (C １ ~C ４ alkyl) ３ with a compound of formula Si—X, wherein X is halo, to provide a compound of formula (II).

14. R １ and R ２ 14. The method of claim 13, wherein each of is methyl.

15. R ３ The method of claim 13 or 14, wherein is trimethylsilyl.

16. 16. The method of claim 13, 14, or 15, wherein X is chloro.

17. 17. The method of any one of claims 13 to 16, wherein the compound of formula (II) has less than 0.5 weight percent multiply alkylated cyclopentadiene as determined by gas chromatography.

18. 18. The method of any one of claims 13 to 17, wherein the compound of formula (II) is devoid of dicyclopentadiene.

19. 19. The method of any one of claims 13 to 18, further comprising treating the compound of formula (II) with a Group IV, Group V, or Group VI metal halide.

20. The metal halide is TiCl ４ 20. The method of claim 19, wherein:

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