Synthesis of chiral sulfines by oxidation of dithio esters

Abstract

Recueil des Truuuiu Chimiqiies des ED Nijmegen, The Netherlands (Receiued September 12, 1994) Abstract.T h e synthesis of sulfines (thione oxides) (2, 10 and 17) derived from three chiral dithio esters (1, 8 and 16) bearing a hydrogen a t the a-carbon atom is described. T h e sulfine bearing an amido group at C-a (2), does not racemizc and proved to be stable over a long pcriod.When C-a in the sulfine (10) bears a n acetoxy group the optical activity remained unchanged for ii period of two months; after longer storage a rearrangement to a mixture of dithioperoxy ester 12 and S-methyl ester 11 took place. With an alkyl group at C-a, the sulfine 17 undergoes a fast racemization and rearranges slowly to a mixture of S-ethyl ester 14, dithioperoxy ester 18 and S-vinyl thiosulfinate 19.