Trimethyl borate-induced one-pot homologation reactions of isoquinoline with di-tert-butyl-TMP zincate

Novel one-pot homologation reactions of isoquinoline and quinoline with di-tert-butyl-TMP zincate/trimethyl borate are described. 1-tert-Butyl-3,4-dihydroisoquinoline 1 and 1-tert-butylisoquinoline 2 are formed unexpectedly under the presented reaction conditions with relative ease. A reaction mechanism, including 1,2-migration of the tert-butyl group from 1-isoquinolylzincate, is proposed in detail. Migratory aptitudes of other ligands of isoquinolyl zincates are also discussed.