| Research Abstract |
1.Total synthesis of optically acitive chanoclavine-I was successfully accomplished starting from optically active N_<alpha>-tert-butoxycarbony1-4-bromotryptophan methyl ester (1). The key step was the palladium catalyzed cyclization (Heck reaction) of alpha, beta-conjugate ester(2)which was obtained by the conversion of alpha-carboxyl group to aldehyde followed by Wittig reaction, to form tricyclic chclohexa [c, d] indole skeleton (ergoline skeleton).
2.Total synthesis of Y,Y-dimethylallyltryptophan (DMAT,3), which was the common intermediate of all ergot alkaloids biosynthesis, was accomplished starting from 1. The key step was Heck reaction of 1 with 1,1-dimethylallylalcohol (4) to form of N_<alpha>-tert-butoxycarbonyl-4- (2-hydroxy-2-methyl-1-butene-1-yl) -1-tosyltryptophan (5). Compound (5) was dehydrated with TsOH/benzene to form dine (6) which was converted to olefin (7) by 1,4-reduction with Mg/MeOH.
3.Decarboxylative cyclization 5 was failed under various conditions (radical or photo reactions of its thiol, selenol or oxime esters).
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