Reaction of 1-substituted tetrahydro-β-carbolines with activated alkynes-a new original approach to the synthesis of tetrahydroazocino[5,4-b]indoles

The transformations of 1-substituted tetrahydro-β-carbolines by the action of activated alkynes were studied. The action of dimethyl acetylenedicarboxylate in methanol gives products of the opening of the tetrahydropyridine fragment, namely, 2-methoxyalkylindoles. The action of ethyl propiolate in ethanol and of tosylacetylene in methanol gives mixtures of azocino[5,4-b]indoles and 2-alkoxyindoles. The action of ethyl propiolate in acetonitrile gives azocinoindoles.