利用串联N-烷基化/甲亚胺叶立德环加成反应合成高刺桐生物碱的方法。

Approach to the homoerythrina alkaloids using a tandem N-alkylation/azomethine ylide cycloaddition.

作者信息

Pearson William H, Kropf Jeffrey E, Choy Allison L, Lee Ill Young, Kampf Jeff W

机构信息

Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, USA.

出版信息

J Org Chem. 2007 May 25;72(11):4135-48. doi: 10.1021/jo0703799. Epub 2007 Apr 28.

DOI:10.1021/jo0703799

PMID:17465572

Abstract

Synthetic efforts toward the homoerythrina alkaloids 1-3 are described. Two separate model systems guided the pivotal [3 + 2] azomethine ylide cycloaddition cascade to form the A-C rings of these alkaloids. The cycloaddition precursors 63 and 68, prepared in nine and ten steps, respectively, from alkyne 47, each contain an enolizable ketone, a tethered electrophile, and an electron-poor dipolarophile. Heating 63 and 68 with the stannyl amine 17 generated demethoxyschelhammeridine 65 and demethoxyschelhammericine 70, the products of intramolecular azomethine ylide cycloadditions. Subsequent attempts to install the C-3 methoxy group of 1-3 are also described.

摘要

本文描述了对高刺桐生物碱1-3的合成研究。两个独立的模型体系指导了关键的[3+2]甲亚胺叶立德环加成串联反应，以形成这些生物碱的A-C环。环加成前体63和68分别由炔烃47经九步和十步反应制备而成，它们各自含有一个可烯醇化的酮、一个连接的亲电试剂和一个缺电子的亲偶极体。将63和68与甲锡烷基胺17加热，生成了分子内甲亚胺叶立德环加成产物去甲氧基白屈菜红碱65和去甲氧基白屈菜黄碱70。文中还描述了随后引入1-3中C-3甲氧基的尝试。