Reactions of Enaminones with p‐Quinone Methides: Access to 4H‐Chromene and 4H‐Chromen‐4‐one Derivatives

Abstract

AbstractA one‐pot approach for the synthesis of oxygen‐containing heterocycles such as 4H‐chromenes and 4H‐chromen‐4‐ones has been established through the reaction of enaminones with p‐quinone methides (p‐QMs). This transformation basically involves an acid‐catalyzed 1,6‐conjugate addition of enaminones to p‐QMs followed by annulation. In the case of reaction between 2‐hydroxyphenyl‐substituted p‐quinone methides and N,N‐dimethyl enaminones, 4H‐chromene derivatives were obtained in moderate to excellent yields. Similarly, the reaction between simple p‐quinone methides and 2‐hydroxyphenyl‐substituted N,N‐dimethyl enaminones led to 4H‐chromen‐4‐one derivatives in good yields.