Formation and mechanistic implication of a novel thiaazabicyclooctane derivative drug the cycloaddition of n-acetyl cinnamic acid thioamide

Abstract In the course of synthesizing thiopyran 3a , the novel thiaazabicyclooctane derivative 8 , a precursor to 3a , has been isolated as a major product. The formation of 8 provides further insight into the mechanism of the [4 + 2] cycloaddition involving 1a , which we have previously discussed to be an efficient way of generating usefully functionalised dihydrothiopyrans. The structure of compound 8 was established by detailed NMR investigations.