Base-Promoted Formal [3 + 2] Cycloaddition of α‑Halohydroxamates with Carbon Disulfide to Synthesize Polysubstituted Rhodanines

A concise and practical strategy via potassium-carbonate-mediated [3 + 2]-cycloaddition reaction of α-halohydroxamates with the common solvent carbon disulfide for the synthesis of functionalized rhodanine derivatives in good to excellent yields is developed. The present methodology features a wide substrate scope as well as good functional group tolerance. The potential synthetic utility of this protocol is demonstrated by synthesis of a series of natural product derivatives containing rhodamine skeletons.