Rearrangements of Substituted 3-Aza-1,2,5-hexatrienes. 3. The Scope and Versatility of an Extremely Mild 3-Aza-Cope Reaction
作者:Michael A. Walters、Andrew B. Hoem、Colleen S. McDonough
DOI:10.1021/jo951587g
日期:1996.1.1
An investigation of the [3,3]-sigmatropic reaction of substituted 3-aza-1,2,5-hexatrienes to give 4-pentenenitriles is presented. This reaction has been found to occur under a wide variety of reactions conditions (10 are reported) starting from readily available N-allylamides. In contrast to other 3-aza-Cope reactions, this process occurs at room temperature, under essentially neutral conditions, allowing for the facile preparation of substituted nitrile products in moderate to excellent yields. The scope and versatility of this reaction are demonstrated by its use on a wide variety of substrates, including nitrogen- and oxygen-substituted amides. The rearrangements of cis- and trans-4-tert-butyl-N-allylcyclohexanecarboxamides 16a and 16b are reported and were found to give a ratio of axial to equatorial (A:E) products consistent with A:E ratios found for other related sigmatropic reactions. The stereochemical requirements for this reaction appear to be similar to other [3,3]-rearrangements even though the transition state for this rearrangement is most likely neither boat nor chairlike.