Abstract
In connection with our studies on asymmetric synthesis of optically active diterpenes and steroids, introduction of a two carbon unit into the carbonyl group of 5, 5-ethylenedioxy-2-methyl-2-phenylcyclohexanone (1) was examined using several kinds of organometallic reagents as nucleophiles. Although N, N-dimethyl lithioacetamide (4f) could afford the desired 1, 2-addition product (8e), other organometallic reagents (4a-e) simply behaved as bases which cleaved the ketal ring of 1, giving the enol ether (5). Use of 4f-1, 4-diazabicyclo [2, 2, 2] octane complex could further improve the yield of 8e from 26% to 84%.
