González-Esguevillas María, Pascual-Escudero Ana, Adrio Javier, Carretero Juan C
Departamento de Química Orgánica, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid (Spain), Fax: (+34) 914973966.
Chemistry. 2015 Mar 16;21(12):4561-5. doi: 10.1002/chem.201500182. Epub 2015 Feb 5.
The first examples of the catalytic asymmetric 1,3-dipolar cycloaddition of azomethine ylides with acyclic activated 1,3-dienes (and 1,3-enynes) are described. Under copper catalysis, a selective cycloaddition at the terminal γ,δ-C=C bond is observed. In addition, depending on the ligand used, either the exo or the endo adduct can be obtained with high selectivity. Under appropriate reaction conditions, the acyclic 1,6-addition product is detected, suggesting a stepwise mechanism. The resulting C4-alkenyl-substituted pyrrolidines are suitable substrates for further access to polycyclic systems, as highlighted by the preparation of hexahydrochromeno[4,3-b]pyrrole and the tetracyclic core of the alkaloid gracilamine.
本文描述了甲亚胺叶立德与无环活化1,3-二烯（和1,3-烯炔）的催化不对称1,3-偶极环加成反应的首个实例。在铜催化下，可观察到在末端γ,δ-C=C键处发生选择性环加成反应。此外，根据所使用的配体，可高选择性地获得外型或内型加合物。在适当的反应条件下，可检测到无环1,6-加成产物，这表明反应机理为分步机理。所得的C4-烯基取代的吡咯烷是进一步构建多环体系的合适底物，六氢色烯并[4,3-b]吡咯的制备以及生物碱细柱胺的四环核心结构均突出了这一点。
