Reactions of sodium cyanoborohydride with benzothiazolium and Δ 2-thiazolinium cations. Formation of benzothiazolines, thiazolidines and stable thiazaboroles
Sodium cyanoborohydride reduction of benzothiazolium 1 and Δ2-thiazolinium 2 cations give benzothiazolines 3 and thiazolidines 5 alongwith [[o-(disubstituted amino) phenyl] and 2-(dialkylamino) ethyl] thio] boranecarbonitriles (NB) 4 and 6. Because of the heterocyclic structures formed through N→ B coordination and consequent chirality, the latter species constitute mixtures of two diastereomers which are exceptionally stable to acid and base.
