Regiospecific, Enantiospecific Total Synthesis of the Alkoxy-Substituted Indole Bases, 16- e pi - N a -Methylgardneral, 11-Methoxyaffinisine, and 11-Methoxymacroline as Well as the Indole Alkaloids Alstophylline and Macralstonine
2002; American Chemical Society; Volume: 4; Issue: 20 Linguagem: Inglês
10.1021/ol020101x
ISSN1523-7060
AutoresXiaoxiang Liu, Jeffrey R. Deschamp, James M. Cook,
Tópico(s)Berberine and alkaloids research
ResumoA regiospecific, enantiospecific approach to the synthesis of ring-A-substituted indole alkaloids was developed via a doubly convergent strategy. The asymmetric Pictet−Spengler reaction and enolate-driven palladium cross-coupling processes were both executed in stereospecific fashion and served as the stereochemical basis of this approach. The synthesis of 16-epi-Na-methylgardneral (15), 11-methoxyaffinisine (16), and 11-methoxymacroline (22) has been accomplished in high yield and in enantiospecific fashion. Moreover, the key C-19 ketosarpagine system (borane adducts) 19a,b employed for the construction of 11-methoxymacroline (22) was also transformed into alstophylline 25, which resulted in completion of the total synthesis of the bisindole macralstonine (1).
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