Asymmetric induction in the coupling of 5,6-dihydro-1,4-dithiins with chiral aldehydes. A new synthetic approach to polyhydroxylated compounds

A new strategy is designed to synthesize polyhydroxyl compounds (and/or carbohydrates) by coupling of 5,6-dihydro-1,4-dithiins - carrying a vinylic hydrogen atom - with chiral aldehydes and, in sequence, stereoselective removal of the dithiodimethylene dithiin bridge and stereospecific hydroxylation of the resulting polyhydroxyl alkenes. In this paper the study of both coupling and desulfurization steps is reported by the use of 2-phenyl-5,6-dihydro-1,4-dithiin (5) as a model compound in the reactions with three chiral aldehydes, 3a,b and 4. Copyright (C) 1996 Elsevier Science Ltd.