| 主权项 |
1. An enantioselective process for preparation of biologically active (R) and (S) enantiomers of sex pheromones: wherein, the process comprises the steps of: a) subjecting 3,3-dimethylhex-5-en-2-one (2) to Meyer-Schuster rearrangement reaction in presence of ethoxyacetylene and an organolithium reagent, followed by treatment with Lewis acid catalyst and then reduction to obtain racemic (2E,Z)-3,4,4-trimethylhepta-2,6-dien-1-ol (3); b) conducting Claisen rearrangement reaction on compound (3) in presence of alkyl vinyl ether and source of mercury ion, followed by reduction to obtain racemic 3,4,4-trimethyl-3-vinyl-hept-6-en-1-ol (4); c) esterifying alcohol (4) with a chiral acid in presence of a coupling agent and base to obtain a mixture of diastereomers (5a) and (5b) followed by chiral separation; d) hydrolyzing diastereomer (5a) and (5b) separately in alkaline medium followed by acetylation in presence of acetic anhydride, acetic acid, or acetyl chloride to obtain R and S enantiomer of (3,4,4-trimethyl-3-vinyl-hept-6-enyl) acetate (6a) and (6b); and e) subjecting compound (6a) and (6b) to ring closure metathesis in presence of (Grubbs-II catalyst) [1,3-bis-(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro(phenylmethylene) (tricyclohexyl phosphine) ruthenium to obtain the S and R enantiomers 2-(1,5,5-trimethylcyclopent-2-en-1-yl)ethyl acetate. |
