PROCESS FOR THE PRODUCTION OF 2-METHYL-4-(2,6,6-TRIMETHYL-1-CYCLOHEXEN-1-YL)-2-BUTENAL

Abstract

The present invention relates to an improved way to produce 2-methyl-4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-butenal and derivatives thereof.

Claims

1. A process for the production of the compound of formula (I) ##STR00009## wherein as first step (step (i)) a Darzens reaction is carried out between a compound of formula (II) ##STR00010## wherein R.sub.1 is H or CH.sub.3, preferably wherein R.sub.1 is H, and a compound of formula (III) ##STR00011## wherein X is Cl or Br, preferably wherein X is Cl, and R.sub.2 is C.sub.1-C.sub.4-alkyl, preferably methyl or ethyl, in the presence of MOR, wherein R is a C.sub.1-C.sub.4-alkyl group (preferably methyl or ethyl), and M signifies Na.sup.+, K.sup.+ or Cs.sup.+, wherein from 1.0 to 1.3 mol equivalents of the compound of formula (III), based on the amount of the compound of formula (II), and from 1.0 to 1.4 mol equivalents of MOR, based on the amount of the compound of formula (II), is used, followed by a second step (ib) whereby a saponification reaction in the presence of NaOH to form the compound of formula (V) ##STR00012## takes place and in step (ii) the compound of formula (V) is undergoing a decarboxylation reaction to form the compound of formula (I), wherein a reaction temperature of less than 30° C. is applied.

2. The process according to claim 1, wherein step (i) is carried out in at least one solvent.

3. The process according to claim 2, wherein step (i) is carried out in at least one aliphatic alcohol, in at least one aliphatic hydrocarbon, and/or in at least one aromatic hydrocarbon.

4. The process according to claim 3, wherein step (i) is carried out in at least one solvent chosen from aliphatic C.sub.1-C.sub.6 alcohols, and aliphatic C.sub.5-C.sub.10-hydrocarbons.

5. The process according to claim 1, wherein step (ia) is carried out at a reaction temperature in the range of from −5° C. to 5° C.

6. The process according to claim 1, wherein from 1.0 mol equivalents up to 1.2 mol equivalents of the compound of formula (III), based on the amount of the compound of formula (II), and/or from 1.0 mol equivalents up to 1.3 mol equivalents of MOR, based on the amount of the compound of formula (II), wherein R is a C.sub.1-C.sub.4-alkyl group, and M signifies Na.sup.+, K.sup.+ or Cs.sup.+, are used.

7. The process according to claim 1, wherein step (ib) is carried out a temperature in the range of from 15° C. to 30° C.

8. The process according to claim 1, wherein step (ib) is carried out at room temperature.

9. The process according to claim 1, wherein step (ii) is carried out a temperature in the range of from 15° C. to 30° C.

10. The process according to claim 1, wherein step (ii) is carried out at room temperature.

11. The process according to claim 1, wherein step (ii) is carried out under normal pressure.

Description

EXAMPLES

Example 1

[0039] β-lonone (17.6 ml, 84 mmol), chloroacetic acid methyl ester (8.2 ml, 93 mmol), methanol (1.9 ml) and n-hexane (1.9 ml) were added to a flask. The solution was cooled to 0° C. Sodium methylate (5.00 g, 93 mmol) was slowly added. The reaction mixture was warmed to room temperature and stirred for 30 min. Aqueous sodium hydroxide (10 ml) in methanol (90 ml) was added over 30 min. Water (150 ml) was added. The reaction mixture was stirred for 10 min. n-Hexane (40 ml) was added and the layers were separated. The aqueous layer was extracted with n-hexane (2×50 ml). The combined organic layers were washed twice with acetic acid (2×16 ml). The organic layer was dried over Na.sub.2SO.sub.4, filtered, and concentrated in vacuo. 2-Methyl-4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-butenal was obtained (21.0 g, 82% yield, quantitative conversion).