Synthesis of Polysubstituted Furan-Fused 1,4-Thiazepine Derivatives

Significance

A methodology for the synthesis of 1,4-thiazepines, involving a multicomponent reaction between thiazole carbenes, substituted ketenes, and activated alkynes is reported. The ketene-forming acid chloride tolerates a wide range of both arylic and alkylic substituents. The base i-Pr₂NEt has been shown to be superior in ketene formation. The methodology provides a wide range of derivatives in good to excellent yields. A plausible mechanism for the multicomponent reaction is presented.