Bridged-ring nitrogen compounds. Part 3. Synthesis of representatives of the 1,5-methano-4-benzazonine ring system

Abstract

Reaction of arylaldehydes with 2,4-dimethylpyridine and n-butyl-lithium gives in good yield 1-aryl-2-(4-methylpyridyl)ethanols which, after dehydration with polyphosphoric acid and catalytic hydrogenation, give 2-phenethyl-4-methylpyridines. Cyclisation of the derived tetrahydropyridines gives 1,4-dimethyl-2,3,4,5,6,7-hexahydro-1,5methano-1H-4-benzazonines except when cyclisation is attempted meta to a methoxy-group.