Bromine Complexes of Polyvinylpyrrolidone Supports: A Mild Reagent for the Transformation of α‐Oxoketene Dithioacetals to β‐Oxothiolesters

Abstract

When α‐oxoketene dithioacetals 1a–n were treated with the bromine complex of a copolymer of 1‐vinyl‐2‐pyrrolidone and 4‐vinylpyridine, the corresponding thiolcarboxylates 2a–n were formed in excellent yields. The reaction also works with other 1‐vinyl‐2‐pyrrolidone‐derived polymers as well as commercially available polyvinylpyrrolidone–bromine complexes. The method is suitable for preparing aliphatic, aromatic, and γ,δ‐unsaturated β‐oxothiolcarboxylates.

Keywords:

• Ketene dithioacetals
• thiolesters
• polymer supports
• bromine complexes
• polyvinylpyrrolidone

Acknowledgments

This work was supported by Kerala State CSTE and CSIR New Delhi (Project No. 01[1954]/04/EMR‐II). We thank MK University, Madurai, and SIF, Bangalore, for providing spectral and analytical data. P. M. thanks the UGC for assistance under the Faculty Improvement Program. S. K. M. thanks MGU for a research fellowship.