Asymmetric Methylene Transfer Reactions II: Asymmetric Synthesis of Oxiranes from Carbonyl Compounds by Methylene Transfer Reaction using Chiral S-Neomenthyl and S-exo-2-Bornyl Sulfoximines

Article abstract of DOI:10.1016/0957-4166(95)00219-F

Three chiral sulfoximines, viz., (1R,Ss)-(-)-S-methyl-S-exo-2-bornyl-N-tosyl sulfoximine, 9a, its epimer at sulfur (1R,Rs)-(+)-9b, and (1R,3S,4S,1'S,Rs)-(+)-S-methyl-S-neomenthyl-N-(camphor-10-sulfonyl) sulfoximine, 19, were used as methylene transfer reagents in the preparation of nonracemic oxiranes (enantiomeric excess, 19-86percent) from prochiral carbonyl compounds.Sulfoximines 9a and 9b were found to be less effective (ee, 19-68percent) than the corresponding S-neomenthyl sulfoximines 2a and 2b (ee, 56-86percent), and, sulfoximine 19, despite having a chiral auxiliary on nitrogenin place of the tosyl group, was found to be only as effective as the corresponding N-tosyl sulfoximine 2b in influencing the steric course of these reactions.The absolute configuration at sulfur of all the synthesised sulfoxides and sulfoximines has been established by X-ray studies.