Asymmetric [3 + 2] Cycloaddition Employing <i>N</i>,<i>N′</i>-Cyclic Azomethine Imines Catalyzed by Chiral-at-Metal Rhodium Complex
作者:Jun Gong、Qian Wan、Qiang Kang
DOI:10.1021/acs.orglett.8b01264
日期:2018.6.1
An efficient asymmetric 1,3-dipolar cycloaddition of α,β-unsaturated 2-acyl imidazoles with N,N′-cyclic azomethine imines catalyzed by a chiral-at-metal rhodium complex is reported. The corresponding N,N′-bicyclic pyrazolidine derivatives with three contiguous tertiary stereocenters were obtained in good yields (up to 99%) with excellent stereoselectivities (>20:1 dr and >99% ee). Remarkably, as little
报道了由手性金属铑配合物催化的α,β-不饱和2-酰基咪唑与N,N′-环偶氮甲亚胺的有效不对称1,3-偶极环加成反应。获得具有三个连续的叔立体中心的相应的N,N′-双环吡唑烷衍生物,具有良好的产率(高达99%)和优异的立体选择性(> 20∶1dr和> 99%ee)。显着地,低至0.5mol%的手性Rh(III)配合物可以以优异的产率和对映选择性促进克级反应。