Palladacycles bearing pendant benzamidinate ligands as catalysts for the Suzuki and Heck coupling reactions

Abstract

Three pendant benzamidines [Ph–C( NC 6H 5)–{NH(CH 2) 2NMe 2}] ( 1 ), [Ph–C( NC 6H 5)–{NH(CH 2Py)}] ( 2 ) and [Ph–C( NC 6H 5)-{NH( o-C 6H 4)(oxazoline)}] ( 3 ) are described. Reactions of 1 , 2 or 3 with one molar equivalent of Pd(OAc) 2 in THF give the palladacyclic complexes [Ph–C{–NH(η 1-C 6H 4)}{ N(CH 2) 2NMe 2}]Pd(OAc) ( 4 ), [Ph–C{–NH(η 1-C 6H 4)}{ N (CH 2Py)}]Pd(OAc) ( 5 ) and [Ph–C{–NH(η 1-C 6H 4)}{ N( o-C 6H 4)(oxazoline)}]Pd(OAc) ( 6 ), respectively. Treatment of 4 , 5 or 6 with excess of LiCl in chloroform affords [Ph–C{–NH(η 1-C 6H 4)}{ N(CH 2) 2NMe 2}]PdCl ( 7 ), [Ph–C{–NH(η 1-C 6H 4)}{ N(CH 2Py)}]PdCl ( 8 ) and [Ph–C{–NH(η 1-C 6H 4)}{ N( o-C 6H 4)(oxazoline)}]PdCl ( 9 ). The crystal and molecular structures are reported for compounds 1 , 3 , 5 , 6 and 7 . The application of these palladacyclic complexes to the Suzuki and Heck coupling reactions was examined.