Engaging Allene-Derived Zwitterions in an Unprecedented Mode of Asymmetric [3+2]-Annulation Reaction
作者:Muthukumar G. Sankar、Miguel Garcia-Castro、Christopher Golz、Carsten Strohmann、Kamal Kumar
DOI:10.1002/anie.201603936
日期:2016.8.8
addition of chiral phosphine, that is, (R)‐ or (S)‐SITCP, to an α‐substituted allene ester generated a zwitterionic dipole. Under optimized reaction conditions, this dipole could engage isatine‐derived N‐Boc‐ketimines in a novel mode of [3+2] annulation reaction. Pyrrolinyl spirooxindoles are thus afforded in high yields and with excellent enantioselectivities. The unprecedented annulation reaction successfully
将手性膦((R)-或(S)-SITCP)催化加成到α-取代的烯丙基酯中会生成两性离子偶极子。在优化的反应条件下,该偶极子可以以[3 + 2]环化反应的新型模式与源自芥子碱的N - Boc-酮亚胺结合。因此以高收率和优异的对映选择性提供了吡咯啉基螺硫辛酯。前所未有的成环反应成功地促进了支持许多手性中心的富含sp 3的且高度取代的3,2'-吡咯烷基磺酰螺环的构建。