Process for preparing unsaturated esters

A compound and solvent technology, applied in the field of preparing 4-methyl-6-hex-3-alkenoic acid alkyl ester, can solve problems such as expensive

Active Publication Date: 2017-04-12
AROMOR FLAVORS & FRAGRANCES LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] The disadvantage of this method is the use of the relatively expensive catalyst calcium 2-ethylhexanoate

Method used

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  • Process for preparing unsaturated esters
  • Process for preparing unsaturated esters
  • Process for preparing unsaturated esters

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Preparation of high E ethyl 4-methyl-6-(2,6,6-trimethylcyclohex-1-en-1-yl)hex-3-enoate (4, R=ethyl).

[0036] While stirring, 2-methyl-4-(2,6,6-trimethylcyclohex-1-en-1-yl)butanal (1) (10 g, 79% purity), dimethylethyl Amide (12 g), monoethyl malonate (8 g, Alfa Aesar 96% purity) and MgCl 2 (2.75g Sigma, anhydrous, >98%) was heated to 120°C and then stirred at this temperature for 2 hours. The yield in terms of purity according to GC analysis was 81% for the E-4 isomer and 11% for the Z-4 ​​isomer (ratio E / Z=88:12). The sum of the isomers was 75% based on the internal standard.

[0037] Cool the reaction mixture to 60 °C and separate the lower MgCl 2 - DMAC phase, the organic phase is washed with water and distilled at 120-130° C. / 0.1 mm.

[0038] After distillation, the E isomer content was 71% and the Z isomer content was 9.5%.

Embodiment 2

[0040] Preparation of high E ethyl 4-methyl-6-(2,6,6-trimethylcyclohex-1-en-1-yl)hex-3-enoate (4, R=ethyl).

[0041] 2-Methyl-4-(2,6,6-trimethylcyclohex-1-en-1-yl)butanal (1) (10g, 79% purity), dimethylacetamide (10g) , monoethyl malonate (5.5 g) and LiCl (2 g) were heated to 130° C. for 1 hour. Monoethyl malonate (9 g) was then added at 130°C for 3 hours. The reaction mixture was cooled and stirred with water (50 g) and hexane (15 ml). The organic phase was separated and washed 3 times with 20 ml of water, then the solvent was evaporated under reduced pressure to provide a compound containing 52% E-4 isomer, 9.5% Z-4 isomer and 10% conjugated isomer 6 according to GC analysis. 12g of crude product. The yield of the E isomer was 59% in purity.

Embodiment 3

[0043] Preparation of 4-methyl-6-(2,6,6-trimethylcyclohex-1-en-1-yl)hex-3-enoic acid (4, R=H) with high E

[0044] 2-Methyl-4-(2,6,6-trimethylcyclohex-1-en-1-yl)butanal (1) (10g, 79% purity), dimethylacetamide (12g) , malonic acid (8g) and MgCl 2 (3 g) was heated to 130°C and held for 2 hours.

[0045] According to GC analysis, the reaction mixture contained 39.6% of E-monocyclic homofarnesic acid (4, R=H) and 14.5% of the corresponding Z-4 isomer.

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Abstract

The present invention provides a method for preparing 4-methyl-6-(2,6,6-trimethylcyclohex-1-enyl)hex-3-enoic acid alkyl ester (4), the method comprising making 2 ‑Methyl‑4‑(2,6,6‑trimethylcyclohex‑1‑en‑1‑yl)butyraldehyde (1) in a single step reaction with monoalkyl malonate (5); where R selected from H, C1-C4 alkyl.

Description

technical field [0001] The present invention provides a process for the preparation of alkyl 4-methyl-6-(2,6,6-trimethylcyclohex-1-enyl)hex-3-enoate, which is used in the synthesis of succinate family Useful precursors for products (eg 3a, 6, 6; 9a-tetramethyldodecahydronaphtho[2; 1-b]furan). Background technique [0002] References considered to be relevant as background to the presently disclosed subject matter are listed below: [0003] WO2012085056 teaches the synthesis of 4-methyl-6-(2,6,6-trimethylcyclohex-1-enyl)hex-3-enoic acid alkyls with high E-isomer content in two steps Esters (3). In the first step described in WO2011073387, 2-methyl-4-(2,6,6-trimethylcyclohexyl-1- Knoevenagel condensation of en-1-yl)butyraldehyde (1) with dialkyl malonate (2) affords intermediate conjugated malonate 3. [0004] [0005] The disadvantages of this method are attributed to the corrosive and fuming properties of titanium tetrachloride and the use of carbon tetrachloride, an ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C69/608C07C67/343C07C57/26C07C51/347
CPCC07C403/20C07C2601/16
Inventor Y·贝克尔M·切斯克斯
Owner AROMOR FLAVORS & FRAGRANCES LTD
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