SYNTHESIS OF OPTICALLY-ACTIVE BICYCLO[222]OCTANES - SUBSTITUTION EFFECT OF THE CYCLOHEXENONE RING ON THE SEQUENTIAL MICHAEL REACTION

Reactions of the cross-conjugated dienolate of 3-substituted 2-cyclohe xenone 1b and 1c, 2-cyclohexenone (1d), and 2,3-disubstituted 2-cycloh exenone le with methyl (S)-3-(2,2-dimethyl-1,3-dioxolan-4-yl)-2-propen ate (Z)-2 gave highly diastereoselectively 3b, 3c, 3d and 3e, respecti vely. The presence of a methyl group at C-6 on cyclohexenone ring caus ed the stereoselectivity to change completely, so that the reaction of the lithium enolate of 9 with (Z)-2 and with (E)-2 gave predominantly 11 and 12, respectively.