Small and Medium-Sized Bridgehead Bicyclic Lactams: A Systematic ab Initio Molecular Orbital Study

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• 作者：Arthur Greenberg ; David T. Moore ; and Thomas D. DuBois
• 刊名：Journal of the American Chemical Society
• 出版年：1996
• 出版时间：September 11, 1996
• 年：1996
• 卷：118
• 期：36
• 页码：8658 - 8668
• 全文大小：290K
• 年卷期：v.118,no.36(September 11, 1996)
• ISSN：1520-5126

文摘

Optimized ab initio molecular orbital calculations onnine bridgehead bicyclic lactams ranging from the2.2.2 to the 4.3.3 series indicate variations in structural properties,resonance energies, proton affinities, and coreorbital ionization energies that reflect thetrans-cycloalkene analogy. The smaller lactams arecalculated to beN-protonated, the larger O-protonated, and the "crossover" ispredicted to occur around the 3.3.1 system. On thebasis of resonance energies, larger bridgehead bicyclic lactams couldbe considered to be hyperstable as Schleyerand co-workers define the concept for larger bridgehead alkenes.This, hyperstability should be apparent in thekinetics of the nucleophilic substitution reactions of the lactams,such as hydrolysis, but not in the thermochemistryof these reactions.