Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

Abstract

An electrochemical version of the Corey–Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/H2O (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much more environmentally friendly than the classical reaction, where a large excess of trialkyl phosphite as reducing agent and high temperatures are required. Thus, cathodic reduction at room temperature of two cyclic thiocarbonates (−1.2 to −1.4 V vs Ag/AgCl) afforded the corresponding alkenes, trans-6-(pent-1-enyl)-α-pyrone and trans-6-(pent-1,4-dienyl)-α-pyrone, which are naturally occurring metabolites isolated from Trichoderma viride and Penicillium, in high chemical yield and with excellent stereo selectivity.

In Situ Formation of RSCl/ArSeCl and Their Application to the Synthesis of 4-Chalcogenylisocumarins/Pyrones from o-(1-Alkynyl)benzoates and (Z)-2-Alken-4-ynoates

“…Isocoumarins − and pyrones, , the core structures of many naturally occurring compounds, have been found to display a broad spectrum of biological activities including antimicrobial, − androgen-like, phytotoxic, antifungal, , and pheromonal effects. On the other hand, the past decade has witnessed a growing interest in organochalcogenide compounds, since the installation of chalcogen functional groups into organic molecules can significantly improve their physical and chemical features as well as enhance their biological activities. − …”