Leveraging the Persistent Radical Effect in the Synthesis of trans-2,3-Diaryl Dihydrobenzofurans

A simple method for accessing trans-2,3-diaryl dihydrobenzofurans is reported. This approach leverages the equilibrium between quinone methide dimers and their persistent radicals. This equilibrium is disrupted by phenols that yield comparatively transient phenoxyl radicals, leading to cross-coupling between the persistent and transient radicals. The resultant quinone methides with pendant phenols rapidly cyclize to form dihydrobenzofurans (DHBs). This putative biomimetic access to dihydrobenzofurans provides superb functional group tolerance and a unified approach for the synthesis of resveratrol-based natural products.

Automated summary

A simple method for accessing trans-2,3-diaryl dihydrobenzofurans is described in this article. The method takes advantage of the equilibrium between quinone methide dimers and their persistent radicals. Phenols are used to disrupt this equilibrium and generate transient phenoxyl radicals, allowing for cross-coupling between the persistent and transient radicals. The resulting quinone methides with pendant phenols rapidly cyclize to form dihydrobenzofurans (DHBs), providing a biomimetic approach for the synthesis of resveratrol-based natural products.