SYNTHESES OF QUINOLINES, DIHYDROHYDROQUINOLINE AND TETRAHYDROQUINOLINE VIA ORTHO-QUINONE METHIDE IMINE INTERMEDIATE

A general process for ortho-specific hydroxyalkylation of secondary an ilines via N-allcylanilinochlorophenylboranes has been developed. Pyro lysis of the resulting ortho-aminobenzyl alcohols generated the corres ponding ortho-quinone methide imines, which can participate in an elec trocyclic reaction to yield 2-substituted-1,2-dihydroquinolines. The r esulting dihydroquinolines can be converted readily to a variety of 2- substituted quinolines. Intramolecular trapping of the ortho-quinone m ethide imines with an olefin via a [2+4] cycloaddition reaction leads to the syntheses of various polycyclic tetrahydroquinolines. Copyright (C) 1996 Elsevier Science Ltd