Isao Agata

A Novel Entry to Pyrido[4,3-b]carbazoles: An Efficient Synthesis of Ellipticine

Abstract The palladium catalyzed tandem cyclization–cross-coupling reaction of indolylborate (2) with vinyl bromide (9) was developed for the preparation of pyrido[4,3-b]carbazole as a key reaction. The cross-coupling reaction of 2a provided hexatriene (10), and then cyclization of 10 to pyrido[4,3-b]carbazole (12) was effected with irradiation or Lewis acid. Using indolylborate (2c) for the cross-coupling reaction, a novel construction of ellipticine was attained through similar reaction sequences.

1,3,5-Tri-O-caffeoylquinic acid from Xanthium strumarium

Abstract A new polyphenol, 1,3,5-tri- O -caffeoylquinic acid, accompanied by 3,5-di- O -caffeoylquinic acid, has been isolated from the fruit of Xanthium strumarium .

A tetrameric derivative of caffeic acid from Rabdosia japonica

Abstract A component which showed tanning activities, was isolated from Rabdosia japonica , and was named rabdosiin. It was shown to be a tetramer of caffeic acid with a lignan skeleton.

A concise access to 2-allenylindole derivatives based on the palladium catalyzed cross-coupling reaction of indolylborates

Abstract The palladium catalyzed cross-coupling reaction of trialkyl(indol-2-yl)borates with prop-2-ynyl carbonates was developed for the preparation of 2-allenylindole derivatives. When the reaction of indolylborates with tert -prop-2-ynyl carbonates was carried out, 2-allenylindoles were obtained solely. Otherwise, indolylborates reacted with sec -prop-2-ynyl carbonates, giving rise to 2-allenylindoles and/or 3-(prop-2-ynyl)-indoles depending on the catalyst used.

A novel one-pot route to cyclopenta [b]indole via the palladium-catalysed carbonylative cross-coupling reaction of indolylborate with prop-2-ynyl carbonate

A novel one-pot protocol for the formation of cyclopenta[b]indole is developed via the palladium catalysed carbonylative cross-coupling reaction.