Deprotonation of β,β-disubstituted α,β-unsaturated amides - Mechanism and stereochemical consequences
作者:James R Green、Marek Majewski、Victor Snieckus
DOI:10.1139/v06-112
日期:2006.10.1
detailed study of the lithium dialkylamide induced deprotonation of β,β-disubstituted α,β-unsaturated amides is presented. The preferential γ-Z-deprotonation and stereochemical outcome of substituents on the γ-Z carbon atom are rationalized in terms of a cyclic eight-membered transition state, which is supported by DFT calculations. Analogous deprotonations on cyclohexylidenecarboxamides reveal a delicate
详细研究了二烷基酰胺锂诱导 β,β-二取代 α,β-不饱和酰胺去质子化。γ-Z 碳原子上取代基的优先 γ-Z-去质子化和立体化学结果在循环八元过渡态方面被合理化,这得到了 DFT 计算的支持。亚环己基甲酰胺的类似去质子化揭示了对八元环状过渡态的偏好与环上现有取代基的影响和扭船过渡态的干预之间的微妙平衡。 关键词:二烯醇,酰胺,去质子化机制,过渡状态、烯醇化、区域选择性、立体选择性。