2001 diastereoselective syntheses, enantioselective syntheses

diastereoselective syntheses, enantioselective syntheses (incl. cis/trans-isomerism)O 0031

14 - 035Highly Stereoselective Additions of Sulfur Stabilized Carban-ions to [(S)R]-2-(p-Tolylsulfinyl)cyclohexanones. — Lithiatedα-thiocarbanions derived from sulfoxides, sulfones, and thioethers undergoasymmetric addition to a C-2 epimeric mixture of sulfinylcyclohexanone (I) toafford the corresponding tertiary carbinols in a highly diastereoselective manner.The stereoselectivity is controlled by the configuration of the sulfinyl group atthe cyclohexanone, but it is modulated by the nature of the sulfur functionat the carbanion. In the reactions of sulfinylcyclohexanone (I) with prochiralanions, a highly stereoselective formation of the second generated stereogeniccenter is only achieved with sulfinylcarbanions, the configuration of whichcontrols that of such a center, whereas in the case of racemic carbanions derivedfrom sulfoxides or carbanions derived from sulfones, the diastereoselectivityof the reaction is low. — (GARCIA RUANO, JOSE L.; BARROS, DAVID;MAESTRO, M. CARMEN; MARTIN CASTRO, ANA M.; RAITHBY, PAULR.; Tetrahedron: Asymmetry 11 (2000) 21, 4385-4395; Dep. Quim. Org., Univ.Auton., Cantoblanco, E-28049 Madrid, Spain; EN)

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