Asymmetric synthesis using enantiomerically pure 2-(p-anisylsulfinyl)-2-cycloalkenones

Conjugate additions of many organometallic reagents to 2-(p-anisylsulfinyl)-2-cycloalkenones, 2 proceed with much greater diastereoselectivity than additions to the corresponding 2-(p-tolylsulfinyl)-2-cycloalkenones, 7. Complexation of 2 with zinc dibromide followed by addition of various Grignard reagents lead, after reductive removal of the sulfoxide, to 3-substituted cycloalkanones of higher optical purity than those obtained from 7. Addition of methyltitanium triisopropoxide to 2-(p-anisylsulfnyl)-2-cyclohexenone, 2b, in the absence of zinc dibromide, proceeds with virtually complete asymmetric induction.