LEWIS ACID-PROMOTED 3-AZA-COPE REARRANGEMENT OF N-ALKYL-N-ALLYLANILINES
LEWIS ACID-PROMOTED 3-AZA-COPE REARRANGEMENT OF N-ALKYL-N-ALLYLANILINES
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DOI：
10.1021/jo00071a018
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发表时间：
1993-09-10
影响因子：
3.6
通讯作者：
STILLE, JR
中科院分区：
文献类型：
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作者：
BEHOLZ, LG;STILLE, JR
N-烷基-N-烯丙基苯胺底物的3-氮杂-COPE重排反应需要250℃才能进行，在111-140℃时，Lewis酸试剂促进了重排反应。对该反应进行了系统的研究，考察了许多反应变量，如浓度、Lewis酸与底物的化学计量比、重排的最佳温度和Lewis酸试剂的类型。在所研究的众多路易斯酸中，氯化锌(140℃)和乙基氟化氢(111℃)是最成功的促进芳香族3-氮杂冠醚重排的试剂。在底物变化方面，N-烯丙基旁的甲氧基取代基的存在使反应略有减慢，而间位取代基的存在加快了[3，3]重排的速度，并在芳环上产生了适度的中心选择性。在Lewis酸的作用下，不对称取代的烯丙基部分发生重排反应，得到芳环上的1-己烯-3-基取代基。总体而言，ZnCl2和Et2OBF3都能有效地促进N-烷基-N-烯丙基苯胺的区域特异性3-氮杂重排，从而在二次烷基取代基和芳香环之间形成碳-碳键。
The 3-aza-Cope rearrangement of N-alkyl-N-allylaniline substrates, which required 250-degrees-C to proceed thermally, was promoted by Lewis acid reagents at 111-140-degrees-C. Systematic studies of this reaction were performed to examine a number of reaction variables such as concentration, the stoichiometry of the Lewis acid with the substrate, the optimum temperature for rearrangement, and the type of Lewis acid reagent. Of the many Lewis acids investigated, ZnCl2 (140-degrees-C) and Et2O.BF3 (111-degrees-C) were the most generally successful reagents for promoting the aromatic 3-aza-Cope rearrangement. With respect to substrate variation, the presence of a methoxy substituent para to the N-allyl group slowed the reaction slightly, while a meta substituent accelerated the rate of [3,3] rearrangement and produced moderate site selectivity on the aromatic ring. Lewis acid-promoted rearrangement of an unsymmetrically substituted allyl moiety resulted in [3,3] sigmatropic rearrangement to give the 1-hexen-3-yl substituent on the aromatic ring. Overall, both ZnCl2 and Et2O.BF3 were shown to efficiently accelerate the regiospecific 3-aza-Cope rearrangement of N-alkyl-N-allylanilines for the purpose of forming a carbon-carbon bond between a secondary alkyl substituent and an aromatic ring.