Abstract
Thiamine ylid formed by the treatment of thiamine hydrochloride with triethylamine reacted with two moles of phenylisocyanate at the thiazolium C-2 position to give the cycloaddition product followed by the carbamoylation of the hydroxyl group. On the other hand, on treatment with strong base as methylsulfinyl carbanion or t-BuOK followed by the reaction with phenylisocyanate, carbamoylation of the amino group proceeded preferentially, then the cycloaddition of two moles of phenylisocyanate at the thiazolium C-2 position occurred, and finally the hydroxyl group was carbamoylated. Diastereoisomers of perhydrofurothiazole derivatives were isolated and the configurations were decided.
