Total Synthesis of Macrocarpines D and E via an Enolate-Driven Copper-Mediated Cross-Coupling Process: Replacement of Catalytic Palladium with Copper Iodide

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• 作者：M. Toufiqur Rahman ; Jeffrey R. Deschamps ; Gregory H. Imler ; Alan W. Schwabacher ; James M. Cook
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：September 2, 2016
• 年：2016
• 卷：18
• 期：17
• 页码：4174-4177
• 全文大小：388K
• 年卷期：0
• ISSN：1523-7052

文摘

An enolate driven copper-mediated cross-coupling process enabled cheaper and greener access to the key pentacyclic intermediates required for the enantiospecific total synthesis of a number of C-19 methyl substituted sarpagine/macroline indole alkaloids. Replacement of palladium (60–68%) with copper iodide (82–89%) resulted in much higher yields. The formation of an unusual 7-membered cross-coupling product was completely inhibited by using TEMPO as a radical scavenger. Further functionalization led to the first enantiospecific total synthesis of macrocarpines D and E.