Indirect Electroreductive Cyclization for Syntheses of Key Intermediates of Several Indole and Ipecac Alkaloids.
作者:Masataka IHARA、Fumihito SETSU、Yuji TOKUNAGA、Keiichiro FUKUMOTO、Yoshitomo KASHIWAGI、Tetsuo OSA
DOI:10.1248/cpb.43.362
日期:——
Indirect electroreductive cyclization of η-bromo-α, β-unsaturated esters 1-6 using Co(III) or Ni(II)complex as an electron-transfer catalyst provided the six membered compounds 7-12, which are useful synthetic intermediates of several indole and ipecac alkaloids.
[Ni(cyclam)](ClO4)(2)-catalyzed indirect electroreduction of olefinic bromides produced six-membered compounds in low to high yields. The synthetic intermediate 49 of Ipecac and Corynanthe alkaloids was obtained in 88% yield in a highly stereoselective manner. Lactam 66, the synthetic precursor of tacamonine, was prepared in 49% yield as a mixture of two diastereoisomers. The electrolysis of the bromoacetates gave the debrominated compounds in good yields.
IHARA, MASATAKA;YASUI, KEN;TANIGUCHI, NOBUAKI;FUKUMOTO, KEIICHIRO, J. CHEM. SOC. PERKIN TRANS. PT 1,(1990) N, C. 1469-1476