STEREOSELECTIVE SYNTHESIS USING A THIANE OXIDE SYSTEM AS A DISPOSABLETEMPLATE

Substitution of the thiane oxide 1, via the corresponding alpha-sulfin yl carbanion, has been explored as a means of obtaining a range of fun ctionalised products in stereoselective fashion. Whereas reaction of t he alpha-sulfinyl carbanion derived from 1 with either Mel, BnBr or Me 3SiCl results in substitution trans to the sulfoxide oxygen, e.g., to give 3-5, acylation occurs in a stereocomplementary fashion to give ke to sulfoxide products with the new substitutent cis to the sulfoxide o xygen. The change in stereochemical outcome is accompanied by an inver sion of the thiane oxide ring conformation, as demonstrated by X-ray c rystallography. Subsequent manipulation of the initially obtained prod ucts was also examined, e.g. involving desulfinylation or thiane ring opening, to give useful products, such as epoxides, in stereoselective fashion.