Highly Regio- and Diastereoselective Phosphine-Catalyzed [2+4] Annulation of Benzofuran-Derived Azadienes with Allyl Carbonates: Access to Spiro[benzofuran-cyclohexanes]

A novel highly regio-and diastereoselective phosphine-catalyzed [2 + 4] annulation of benzofuran-derived azadienes (BDAs) with acidic hydrogen-tethered allyl carbonates has been developed ingeniously. A range of functionalized spiro[benzofuran-cyclohexane] derivatives with two consecutive stereocenters were smoothly obtained in moderate to excellent yields under mild reaction conditions from readily available materials. Moreover, this method is a practical and scalable strategy that creates the core structural motif of the fungistatic drug, griseofulvin.

Automated summary

A novel phosphine-catalyzed [2 + 4] annulation reaction was developed for the highly regio- and diastereoselective synthesis of functionalized spiro[benzofuran-cyclohexane] derivatives with two consecutive stereocenters. This method involves the reaction of benzofuran-derived azadienes with acidic hydrogen-tethered allyl carbonates and provides moderate to excellent yields under mild reaction conditions. Furthermore, the strategy presented in this study is practical, scalable, and offers a pathway for the synthesis of the core structural motif of the fungistatic drug griseofulvin.