Open AccessAsymmetric synthesis towards (3Z,6R)-3-methyl-6-isopropenyl-3,9-decadien-1-yl acetate, a component of the California red scale pheromone
Author(s) -
Mark Whittaker,
Colin R. McArthur,
Clifford C. Leznoff
Publication year - 1985
Publication title -
canadian journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.323
H-Index - 68
eISSN - 1480-3291
pISSN - 0008-4042
DOI - 10.1139/v85-475
Subject(s) - chemistry , synthon , adduct , hydrolysis , lithium amide , bromide , aldehyde , enantioselective synthesis , amide , organic chemistry , stereochemistry , medicinal chemistry , catalysis
The key chiral synthons, (R)-3-isopropenyl-6-heptenoic acid and (R)-3-isopropenyl-6-heptenal, needed for the synthesis of (3Z,6R)-3-methyl-6-isopropenyl-3,9-decadien-1-yl acetate, a component of the sex pheromone of the California red scale, Aonidiellaaurantii, have been prepared by asymmetric synthesis. The chiral acid was synthesized in 86% ee by an asymmetric 1,4-addition of isopropenylmagnesium bromide to the l-ephedrine amide derived from (E)-2,6-heptadienoic acid, followed by base hydrolysis. Acid hydrolysis gave the chiral 3-(3-buten-1-yl)-4,4-dimethylbutyrolactone. The chiral aldehyde was prepared in greater than 99% ee by an asymmetric 1,4-addition of isopropenylmagnesium bromide to the imine derived from (S)-(+)-tert-butyl 2-amino-3,3-dimethylbutyrate and (E)-2,6-heptadienal. The 1,4-addition reactions of n-butyllithium or isopropenyllithium to (4S,5S)-(+)-2-[1-(E-1,5-hexadienyl)]-4-methoxymethyl-5-phenyl-2-oxazoline gave the addition products, and sequential mild hydrolysis and reduction of these adducts yielded chiral 3-n-butyl-6-hepten-1-ol for the former adduct but a mixture of products was obtained from the latter adduct.