A direct entry into the pyrrolizidine, indolizidine and azaazulene systems is accomplished by reaction of metallated cyclic imines with nitriles and prop-2-ynyl bromide.
通过金属化环状亚胺与腈和 2-炔丙基溴的反应,可直接进入吡咯烷、吲哚利嗪和氮杂环戊烯系统。
An Efficient Approach to Pyrroles and <i>N</i><b>-Bridgehead Pyrroles by Propargylation/Cycloamination of 4-Amino-1-azabutadiene Derivatives</b>
The thermal cycloamination of several propargyl-substituted 4-amino-1-azabutadienes 2 leading to 3-functionalized pyrroles 4-6 is described. Derivatives of pyrrolizidines 9 and indolizidines and azaazulenes 11-13 are synthesized directly from cyclic imines 7 and 10, respectively, in a multistep process that involves metalation with LDA, addition of a nitrile, carbanion trapping with propargyl bromide, and cycloamination. In all cases the more substituted imine nitrogen is involved in the cyclization reaction; such an experimental finding is supported by theoretical calculations.