Enantioselective Heck-Matsuda arylations through chiral anion phase-transfer of aryl diazonium salts

Abstract

A mild, asymmetric Heck–Matsuda reaction of five-, six- and seven-membered ring alkenes and aryl diazonium salts is presented. High yields and enantioselectivities were achieved using Pd⁰ and chiral anion co-catalysts, the latter functioning as a Chiral Anion Phase-Transfer (CAPT) reagent. For certain substrate classes, the chiral anion catalysts were modulated to minimize the formation of undesired by-products. More specifically, BINAM-derived phosphoric acid catalysts were shown to prevent alkene isomerization in cyclopentene and cycloheptene starting materials. DFT(B3LYP-D3) computations revealed that increased product selectivity resulted from a chiral anion dependent lowering of the activation barrier for the desired pathway.