Unexpected Heterocyclic Products from Cycloaddition Reactions of Nonsymmetrical Allenyl Aldoketazines with Substituted Alkynes
作者:Juraj Galeta、Stanislav Man、Jean-Philippe Bouillon、Milan Potáček
DOI:10.1002/ejoc.201001044
日期:2011.1
Thermally initiated cycloaddition reactions of nonsymmetrical allenyl azines 1 with alkynes or other dipolarophiles usually lead to compounds with three fused, five-membered heterocyclic rings. With alkynes with pronounced "push-pull" systems, however, the reaction ends with the formation of substituted pyrrolidino[1,2-b]pyrazoles 4 and, in the case of azines with trifluoromethyl substitution, ring opening
非对称烯丙基吖嗪 1 与炔烃或其他亲偶极体的热引发环加成反应通常会产生具有三个稠合五元杂环的化合物。然而,对于具有明显“推拉”系统的炔烃,反应以形成取代的吡咯烷并 [1,2-b] 吡唑 4 结束,并且在具有三氟甲基取代的吖嗪的情况下,开环导致化合物的分离9. 提出了这些转化的反应机制。通过X射线晶体结构分析证实了新的杂环4和9的分子结构。