AN UNUSUAL FISCHER INDOLE SYNTHESIS WITH 4-KETO ACIDS - AN INDOLE INCORPORATING THE TERMINAL HYDRAZINE NITROGEN
AN UNUSUAL FISCHER INDOLE SYNTHESIS WITH 4-KETO ACIDS - AN INDOLE INCORPORATING THE TERMINAL HYDRAZINE NITROGEN
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DOI：
10.1021/jo00296a063
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发表时间：
1990-04-27
影响因子：
3.6
通讯作者：
SHINKAI, I
中科院分区：
文献类型：
--
作者：
CONN, RSE;DOUGLAS, AW;SHINKAI, I
在从4-酮酸和N-苄基化苯肼前体制备药物活性的N-苄基化吲哚衍生物的过程中，N-未取代的吲哚类似物作为重要的副产物出现。脱苄基吲哚的比例是更大的烷基化，而不是直链酮酸和副产物被完全抑制时，酮酯取代的酮酸。苄基基团被证明已经消除，因为胺和15 N标记掺入证明末端苯肼氮仅掺入吲哚副产物中，这是Fischer吲哚化反应的常规过程的例外。酮亚胺酸中间体中的环链平衡被提出来解释竞争途径。
During preparation of a pharmaceutically active, N-benzylated indole derivative from 4-keto acid and Nr benzylated phenylhydrazine precursors, the N-unsubstituted indole analogue arose as a significant byproduct. The proportion of debenzylated indole was greater with-alkylated rather than straight-chain keto acids and the byproduct was fully suppressed when a keto ester was substituted for the keto acid. The benzylic group was shown to have eliminated as the amine and 15N label incorporation demonstrated terminal phenylhydrazine nitrogen incorporation in the indole byproduct only, an exception to the usual course of the Fischer indolization reaction. A ring-chain equilibration in the ketimino acid intermediate is proposed to account for the competing pathway.