An Efficient Synthesis of a Highly Functionalized Dihydrobenzo­thiophene Derivative: A Ring-Contracted Analogue of the Anti-inflammatory Drug Propoxicam

Abstract

A five-step route to a ring-contracted analogue of the oxicam derivative propoxicam from thiosalicylic acid, sarcosine and N,N-dimethyl-1,3-propanediamine is described. The route has as key steps the base-promoted cross-Claissen coupling of protected sarcosine and thiosalicylic acid derivatives, the installation of a β-ketoamide moiety and a final Hg(II)-induced cyclization that creates the C-S bond of the benzothiophen-3-one core.