Trimethyl borate/magnesium halide complex-induced one-pot homologation reactions of isoquinoline with dialkyl-TMP-zincate

Novel one-pot homologation reactions of isoquinoline with lithium dialkyl-TMP-zincate⋅2MgBrCl/trimethyl borate are described. 1-Alkylisoquinolines (2, 3A, 4A, 5A, 6, and 7) and 1-alkyl-3,4-dihydroisoquinolines (3B, 4B, and 5B) are easily prepared under the presented reaction conditions. The role of the B(OMe)3/MgBrCl complex is examined in these homologation reactions. The specific reaction mechanisms, including 1,2-migration of the alkyl ligands from 1-isoquinolylzincates, are proposed. The migratory aptitudes of ligands of 1-isoquinolylzincates are also discussed.