Synthesis of Azabicycles via Cascade Aza-Prins Reactions: Accessing the Indolizidine and Quinolizidine Cores

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• 作者：Freda K. I. Chio ; S茅bastien J. J. Guesn茅 ; Lorraine Hassall ; Thomas McGuire ; Adrian P. Dobbs
• 刊名：Journal of Organic Chemistry
• 出版年：2015
• 出版时间：October 16, 2015
• 年：2015
• 卷：80
• 期：20
• 页码：9868-9880
• 全文大小：653K
• ISSN：1520-6904

文摘

The first detailed studies of intramolecular aza-Prins and aza-silyl-Prins reactions, starting from acyclic materials, are reported. The methods allow rapid and flexible access toward an array of [6,5] and [6,6] aza-bicycles, which form the core skeletons of various alkaloids. On the basis of our findings on the aza-Prins and aza-silyl-Prins cyclizations, herein we present simple protocols for the intramolecular preparation of the azabicyclic cores of the indolizidines and quinolizidines using a one-pot cascade process of N-acyliminium ion formation followed by aza-Prins cyclization and either elimination or carbocation trapping. It is possible to introduce a range of different substituents into the heterocycles through a judicial choice of Lewis acid and solvent(s), with halo-, phenyl-, and amido-substituted azabicyclic products all being accessed through these highly diastereoselective processes.