Scalable Birch reduction with lithium and ethylenediamine in tetrahydrofuran

Abstract

Easy aryl reductions The Birch reduction has been widely used for more than half a century to achieve partial reduction of aryl rings by alkali metals at just two diametrically opposed carbon sites. However, the conditions require condensation of caustic gaseous ammonia. A variation developed soon afterward by Benkeser used safer liquid ethylene diamine but was prone to overreduction. By diluting ethylene diamine in tetrahydrofuran solvent, Burrows et al . now obtain selectivities comparable to Birch conditions but without the need for condensed ammonia. —JSY