Switchable Regioselective 6-endo or 5-exo Radical Cyclization via Photoredox Catalysis.

ABSTRACT: Controlling the regioselectivity of radical cyclizations to favor the 6-endo mode over its kinetically preferred 5-exo counterpart is difficult without introducing substrate prefunctionalization. To address this challenge, we have developed a simple method for reagent controlled regioselective radical cyclization of halogenated N-heterocycles onto pendant olefins. Radical generation occurs under mild photoredox conditions with control of the regioselectivity governed by the rate of hydrogen atom transfer (HAT). Utilizing a polarity-matched thiol-based HAT agent promotes the highly selective formation of the 5-exo cyclization product. Conversely, limiting the solubility of the HAT reagent Hantzsch ester (HEH) leads to selective formation of the thermodynamically

SUBMITTER: Maust MC 

PROVIDER: S-EPMC8925928 | biostudies-literature | 2022 Mar

REPOSITORIES: biostudies-literature