Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic <i>α</i>-Amino Amides
作者:Jan Blid、Peter Brandt、Peter Somfai
DOI:10.1021/jo035618g
日期:2004.4.1
Boron trifluoride and BBr3 mediated [2,3]-sigmatropic rearrangements of allylicα-amino amides have been developed affording secondary amines in good yields. (E)-Crotyl and (E)-cinnamyl α-amino amides 2b and 2c exhibit excellent syn-diastereoselectivity upon rearrangement with either Lewis acid. The allylic amine 2a forms upon treatment with BF3 or BBr3 a five-membered heterocylic complex in which a
三氟化硼和BBr 3介导的烯丙基的[2,3]-σ重排已经开发出以高收率提供仲胺的α-氨基酰胺。(E)-巴豆基和(E)-肉桂基α-氨基酰胺2b和2c在用任一路易斯酸重排时表现出优异的顺-非对映选择性。烯丙基胺2a在用BF 3或BBr 3处理后形成五元杂环复合物,其中单个卤化物阴离子已被羰基氧原子取代。使用NMR光谱阐明了路易斯酸-胺配合物的结构。提出了一种基于DFT计算的合理反应机理。因此,BF 3-或BBr在去质子化之后,显示3-复合的烯丙基胺2优先通过内过渡态进行。