Synthesis of substituted tetrahydroisoquinolines and benzo[d]azepines from phthalan or isochroman and N-silylaldimines

Abstract

The 4,4′-di-tert-butylbiphenyl-catalyzed lithiation of phthalan (1a) and isochroman (1b) in THF at 0°C affords the corresponding functionalized benzyllithiums 2, which by reaction with N-silylaldimines yield, after acid-base work-up, the expected amino alcohols 3. Successive treatment of these amino alcohols with thionyl chloride and sodium hydroxide yields the corresponding substituted benzofused six- and seven-membered nitrogen-containing heterocycles 4.