Stereochemical Outcomes in Reductive Cyclizations To Form Spirocyclic Heterocycles

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• 作者：Matthew A. Perry ; Richard R. Hill ; Justin J. Leong ; Scott D. Rychnovsky
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：17
• 期：13
• 页码：3268-3271
• 全文大小：371K
• ISSN：1523-7052

文摘

Reductive lithiation and cyclization of N-Boc 伪-amino nitriles are often highly stereoselective. The alkyllithium intermediates are formed with varying levels of selectivity, but the alkyllithium geometry does not play a major role in the overall stereoselectivity. The final configuration is determined in the cyclization reaction, where both retention and inversion pathways are observed. Where strong thermodynamic preferences exist in the products, the kinetically controlled alkyllithium cyclization favors the more stable product.