New stereoselective synthesis of 9-methyl-cis-decalin derivatives by double Michael reaction of 3-methyl-4-methylenecyclohex-2-enone and its congeners with dimethyl 3-oxoglutarate

Abstract

Double Michael reaction of 3-methyl-, 2,3-dimethyl-, and 3,5-dimethyl-4-methylenecyclohex-2-enone with dimethyl 3-oxoglutarate in dimethyl sulphoxide in the presence of potassium fluoride gave stereoselectively 9-methyl-, 1,9-dimethyl-, and 4,9-dimethyl-6,8-dimethoxycarbonyl-cis-decahydronaphthalene-2,7-dione, respectively, and starting from these annulation products some sesquiterpenes having the cis-decahydronaphthalene skeleton were formally synthesised.