METHOXYCARBONYLATION WITH FORMIC ACID AND METHANOL

Abstract

Process for methoxycarbonylation with formic acid and methanol.

Claims

1. Process comprising the process steps of: a) addition of an olefin; b) addition of a compound comprising Pd, wherein the Pd is capable of forming a complex; c) addition of a compound of general formula (I): ##STR00005## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from: H, (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, (C.sub.4-C.sub.14)-aryl, O(C.sub.4-C.sub.14)-aryl, cycloalkyl, (C.sub.1-C.sub.12)-heteroalkyl, O(C.sub.1-C.sub.12)-heteroalkyl, (C.sub.3-C.sub.14)-heteroaryl, O(C.sub.3-C.sub.14)-heteroaryl, COO-alkyl, COO-aryl, CO-alkyl, CO-aryl, NH.sub.2, halogen and the residues are also capable of forming a larger condensed ring; wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen; and at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 does not represent phenyl; d) addition of MeOH; e) addition of HCOOH, wherein the employed volume based on 2 mmol of olefin is in the range from 0.3 ml to 0.8 ml; f) heating of the reaction mixture to convert the olefin into the methyl ester.

2. Process according to claim 1, wherein no CO gas is supplied to the reaction mixture.

3. Process according to claim 1, wherein HCOOH serves as the only CO source for the reaction.

4. Process according to claim 1, wherein the compound in process step b) is selected from: Pd(acac).sub.2, PdCl.sub.2, Pd(dba).sub.3*CH.sub.3Cl (dba=dibenzylideneacetone), Pd(OAc).sub.2, Pd(TFA).sub.2, Pd(CH.sub.3CN)Cl.sub.2.

5. Process according to claim 1, wherein the process comprises the additional process step g): g) addition of an acid.

6. Process according to claim 5, wherein the acid is selected from: H.sub.2SO.sub.4, CH.sub.3SO.sub.3H, CF.sub.3SO.sub.3H, PTSA.

7. Process according to claim 1, wherein the employed volume of HCOOH based on 2 mmol of olefin is in the range from 0.4 ml to 0.6 ml.

8. Process according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, (C.sub.4-C.sub.14)-aryl, O(C.sub.4-C.sub.14)-aryl, cycloalkyl, (C.sub.1-C.sub.12)-heteroalkyl, O(C.sub.1-C.sub.12)-heteroalkyl, (C.sub.3-C.sub.14)-heteroaryl, O(C.sub.3-C.sub.14)-heteroaryl, COO-alkyl, COO-aryl, CO-alkyl, CO-aryl, NH.sub.2, halogen and the residues are also capable of forming a larger condensed ring; wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen; and at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 does not represent phenyl.

9. Process according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from: (C.sub.1-C.sub.12)-alkyl, (C.sub.4-C.sub.14)-aryl, cycloalkyl, (C.sub.1-C.sub.12)-heteroalkyl, (C.sub.3-C.sub.14)-heteroaryl, halogen and the residues are also capable of forming a larger condensed ring; wherein the recited alkyl groups, aryl groups, cycloalkyl, heteroalkyl groups, heteroaryl groups may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen; and at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 does not represent phenyl.

10. Process according to claim 1, wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 are each independently selected from: (C.sub.1-C.sub.12)-alkyl, cycloalkyl, (C.sub.3-C.sub.14)-heteroaryl and the residues are also capable of forming a larger condensed ring; wherein the recited alkyl groups, cycloalkyl, heteroaryl groups may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen, and at least one of the radicals R.sup.1, R.sup.2, R.sup.3, R.sup.4 does not represent phenyl.

11. Process according to claim 1, wherein R.sup.1, R.sup.4 are each independently selected from: (C.sub.1-C.sub.12)-alkyl, cycloalkyl, and the residues are also capable of forming a larger condensed ring; wherein the recited alkyl groups, cycloalkyl may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen.

12. Process according to claim 1, wherein R.sup.2, R.sup.3 each independently represent (C.sub.3-C.sub.14)-heteroaryl, wherein the recited heteroaryl groups may be substituted as follows: (C.sub.1-C.sub.12)-alkyl, O(C.sub.1-C.sub.12)-alkyl, halogen.

13. Process according to claim 1, wherein the compound of general formula (I) has the structure (II): ##STR00006##

Description

[0040] The invention is more particularly elucidated hereinbelow with reference to exemplary embodiments.

[0041] Pd-Catalyzed Methoxycarbonylation of Tetramethylethylene 1a with HCOOH: Effect of Employed Volume of HCOOH

##STR00004##

[0042] Added to a sealed 35 ml tube were [Pd(OAc).sub.2] (1.12 mg, 0.25 mol %), (II) (8.72 mg, 1.0 mol %), p-toluenesulfonic acid (PTSA.H.sub.2O) (15.2 mg, 4 mol %) and an oven-dried stirrer rod. The tube together with the lid were placed into a long Schlenk tube having a large opening. The Schlenk tube is evacuated three times and refilled with argon. Under an argon atmosphere 1a (2 mmol), MeOH (1.5 ml) and HCOOH (X ml) (X see table 1) were injected into the 35 ml tube using a syringe. The 35 ml tube was then sealed with the lid. The reaction was carried out at 100 C. over 13 h. At the end of the reaction the tube was allowed to reach room temperature without additional cooling and carefully decompressed. Isooctane (100 l) was then injected as internal standard. Conversion was measured by GC analysis.

[0043] The results are summarized in table 1 which follows:

TABLE-US-00001 TABLE 1 HCOOH (volume in ml) Conversion % Yield of 2a % Yield of 3a % 0.2 73 53 17 0.3 85 72 11 0.5 91 80 7 0.8 90 71 5

[0044] As is shown by the experiments described above, the problem is solved by a process according to the invention.