Synthesis of 4'-alkyl-[1,1'-biphenyl]-2,3'-dicarbonitriles via dimerisation of phthalonitrile radical anion in liquid ammonia

Abstract

Single-electron reduction of phthalonitrile by metallic lithium in liquid ammonia resulted in a radical anion salt that underwent dimerisation yielding a long-lived intermediate, the 1,2-dicyano-4-(2-cyanophenyl)cyclohexa-2,5-dienyl anion. Alkylation of this anion with primary alkyl iodides resulted in a convenient one-pot synthesis of 4'-alkyl-[1,1'-biphenyl]-2,3'-dicarbonitriles.