Cyclization of Oxa-Bicyclic Alkenes with β-Iodo-(Z)-propenoates and o-Iodobenzoate Catalyzed by Nickel Complexes: A Simple Efficient Route to Annulated Coumarins

Abstract

In the presence of Ni(dppe)Br2 and Zn powder in acetonitrile at 80 °C, oxa-bicyclic olefins undergo cyclization with o-iodobenzoate and with β-iodo-(Z)-propenoates to give the benzocoumarin derivatives in moderate to good yields. This methodology offers a simple efficient way for the synthesis of structurally complicate coumarins in one pot.