Divergent synthesis of δ-valerolactones and furanones palladium or copper-catalyzed α-hydroxycyclopropanol ring opening cyclizations

Cyclopropanols are versatile starting materials which can undergo various ring opening reactions due to their intrisic ring strain. Herein, we report two transition metal-catalyzed α-hydroxycyclopropanol ring opening cyclizations to divergently transform the same α-hydroxycyclopropanol substrate into two different products of enhanced value. One is a palladium-catalyzed α-hydroxycyclopropanol ring opening carbonylative lactonization to synthesize δ-valerolactones. The other one is a copper-catalyzed α-hydroxycyclopropanol ring opening cyclization to access furanones. Divergent approaches were developed to synthesize δ-valerolactones or furanones via a palladium or copper-catalyzed α-hydroxycyclopropanol ring opening cyclizations, respectively.