Origins of Regio- and Stereochemistry in Type 2 Intramolecular N-Acylnitroso Diels鈥揂lder Reactions: A Computational Study of Tether Length and Substituent Effects

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• 作者：Leah Cleary ; Victor W. Mak ; Scott D. Rychnovsky ; Kenneth J. Shea ; Nicholas Sizemore
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：April 19, 2013
• 年：2013
• 卷：78
• 期：8
• 页码：4090-4098
• 全文大小：531K
• 年卷期：v.78,no.8(April 19, 2013)
• ISSN：1520-6904

文摘

Quantum mechanical calculations have been used to investigate type 2 intramolecular N-acylnitroso Diels鈥揂lder reactions. Experimentally observed regioselectivities and diastereoselectivities of these reactions have been reproduced using B3LYP/6-31+G(d) DFT calculations. The factors that govern selectivity (i.e., tether length, tether substitution and diene substitution) were systematically investigated. Tethers less than 6 carbon atoms lead to 1,3-regioisomers due to conformational restrictions. Substituents on the tether lead to diastereoselective outcomes dictated by transannular interactions in the transition states. The modest diastereoselectivity of diene-substituted substrates is rationalized as arising from reduction of eclipsing interactions in the flattened diene transition states. This method should prove valuable for planning syntheses involving type 2 intramolecular Diels鈥揂lder reactions.