CRYSTAL AND MOLECULAR-STRUCTURE OF THE LEVOROTATORY (1R,2S)-EPHEDRINIUM (S)-T-BUTYLSULFINYLACETATE - A DEFINITIVE PROOF OF THE ABSOLUTE-CONFIGURATION OF ENANTIOMERIC T-BUTYL METHYL SULFOXIDES

The levorotatory enantiomer of t-butylsulfinylacetic acid 3 was obtain ed in the reaction of the alpha-carbanion of (+)-t-butyl methyl sulfox ide 1 with carbon dioxide. The same enantiopure form of the acid 3 was isolated from its diastereomerically pure levorotatory salt 5 with (- )-(1R,2S)-ephedrine. The structure of this salt was determined by X-ra y analysis and the absolute configuration (S) at sulfur was ascribed t o the t-butylsulfinylacetate anion. Consequently, the absolute configu ration (S) was assigned to the acid (-)-3 and its precursor (+)-t-buty l methyl sulfoxide 1. (C) 1998 Elsevier Science Ltd. All rights reserv ed.