Development of a 5-exo, 6-exo tandem radical cyclization to access bisabosqual A

Abstract

Substrates were designed to undergo tandem radical cyclizations to afford the cis, cis-fused hexahydrobenzofurobenzopyran ring system of the bisabosquals. Studies with these revealed that different initiating systems gave different yields and somewhat different diastereomeric ratios. A photocatalytic cyclization was also successful with the bisabosqual substrate.