Development of New Reactivities of Indole Nucleus and its Application to Syntheses of Natural Products

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We obtained the following result by studying the titled project.1) We found that quinolone was unexpectedly obtained rather the expected 7-substituted indole in the reduction of 1, 2, 3-trisubstituted nitropyruvate in Reissert indole synthesis2) A variety of approach have been done for the synthesis of lysergic acid. Effort was mainlly focused on the construction of C-ring having nitrogen-containing substituent and simultaneous construction of C and D rings. However synthesis of lysergic acid was not acieved yet. The first synthesis of optically active DMAT, an intermediate of ergot alkaloid was successful3) In relation with the synthesis of lysergic acid, syntheses of new acylating reagents having o-substituted diacylaniline structure and of new ligands for metal-catalysts having asymmetric C-N axis were successful4) We examined to develop new type of reaction in ethyl indole-2-carboylates and to apply them for synthesis of useful substance; I.e., a) convenient synthesis of canthine-6-one using efficient aldol condensation of 1-formyl-β-carboline with ethyl acetate, b) removal of 3-acyl group in indole-2- carboxylates under acidic condition where 3- acylindole has C4- substituent, c) new convenient method to convert 3-acyl group in indoles to 3-alkyl group by catalytic reduction under acidic condition5) We found that existence of 1 and 4-methyl group in N-alkylterahydrocrabazole affects the products distribution in Vilsmeier-Haak reaction. We found new knoledge that in 4, 4-dimethyl compound the products formed due to cleavage of 4-4a bond was formed6) The short and convenient synthesis of benz[g]tryptophan was developed by the reaction of benz[g]indole with serine