STEREOSELECTIVE OXIRANE FORMATION BY REACTION OF DIAZOMETHANE ON -3-[(4-METHYLPHENYL)SULFINYL]-3-PHENYLPROPAN-2-ONE

thyl)-2-{[(4-methylphenyl)sulfinyl][phenyl]methyl} oxirane (4) was obt ained in high chemical yield and with high diastereoselectivity by rea cting diazomethane with pure 3-[(4-methylphenyl)sulfinyl]-3-phenyl-pro pan-2-one (3), but also with its (3S,R(s))-3-diastereoisomer, in the l atter case through inversion of the configuration at carbon 3. The cor responding methyl enol ethers 6 were isolated as by-products. NMR expe riments and molecular modelling calculations were performed in order t o clarify the equilibria in solution and the preferred conformations o f both ketones 3. Several variously substituted, sulfur-free tertiary alpha-(fluoromethyl)carbinols ware obtained from the main reaction pro duct (2S,2'R,R(s))-4 through appropriate elaborations of the sulfinyl group and of the oxirane ring. The structure of(2S,2'R,R,)-4 was estab lished by X-ray analysis of the open-chain derivative 4-methylphenyl)s ulfinyl][phenyl]methyl}propan-2-ol (7).