[Development of unprotected syntheses in aqueous media].
Introduction of carbon side chain at C(3)-position of indole ring was accomplished by using Pd-catalyzed allylation and vinylation. The selective vinylation at C(3)-position of 4-bromoindole was applied to the synthesis of optically active 4-bromotryptophan derivatives, which was used as a starting material for the synthesis of several optically active ergot alkaloids, which were clavicipitic acids, chanoclavine-I, costacalvine, and 1,1-dimethylallyltryptophan (DMAT). The three-step synthesis of optically active clavicipitic acids were accomplished without using a protecting group starting from 4-bromoindole and dl-serine. Some new synthetic reactions using unprotected amino acids were developed. Those were the biomimetic synthesis of tryptophan, the bromination of free aromatic amino acids, and the Pd-catalyzed N-allylation of free amino acids with allylic alcohol in aqueous media. Unique reactivity of π-allyl palladium complex or η3-(benzyl)palladium complex in aqueous media was found through Pd-catalyzed reaction of anthranilic acid, 2-aminobenzamide, and indole with allylic alcohols or benzyl alcohols, respectively.
Faculty of Pharmaceutical Sciences, Toho University, Chiba, Japan. yokoyama@phar.toho-u.ac.jp
Yuusaku
Y
Yokoyama
D000596:Amino Acids / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D004876:Ergot Alkaloids / Q000138:chemical synthesis*; D007211:Indoles / Q000737:chemistry; D055601:Organic Chemistry Phenomena; D010165:Palladium / Q000737:chemistry; D014867:Water; D062367:ortho-Aminobenzoates / Q000737:chemistry
D000596:Amino Acids; D004876:Ergot Alkaloids; D007211:Indoles; C524935:clavicipitic acid; D062367:ortho-Aminobenzoates; D014867:Water; C031385:anthranilic acid; D010165:Palladium; D002244:Carbon