Transformation of indole alkaloids—I
1973; Elsevier BV; Volume: 29; Issue: 14 Linguagem: Inglês
10.1016/0040-4020(73)80138-3
ISSN1464-5416
AutoresNorio Aimi, Etsuji Yamanaka, Jun Endo, Shuichi Sakai, Joju Haginiwa,
Tópico(s)Asymmetric Synthesis and Catalysis
ResumoChemical conversion of some natural oxindoles (pteropodine, isopteropodine and isorhynchophylline) into the corresponding indole alkaloids has been made by way of a sequence of reactions which include formation of iminoethers of the natural oxindoles with Meerwein's reagent, reduction of the iminoethers to 2,3-seco-indoles and cyclization of 2,3-seco-indoles to the desired natural indole alkaloids. Sodium borohydride in acetic acid was found to be a specific reagent for the reduction of oxindole-iminoethers to 2,3-seco-indoles which were the key intermediates in these transformations. Yohimbine-oxindole iminoether was similarly converted to yohimbine and pseudoyohimbine. A number of by-products were obtained and their structures were elucidated.
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