3-dipolar cycloaddition reactions between acyclic carbonyl ylides generated from donor–acceptor oxiranes and aldehydes are reported. Both aromatic and aliphatic aldehydes could be used as dipolarophiles, providing cis-1,3-dioxolanes with high diastereo- and enantioselectivities. On the basis of mechanistic studies, a monomeric chiral Ni(II) complex was hypothesized to act as the active species for the cycloaddition
手性联
萘二
亚胺-Ni(II) 催化的不对称 1,3-偶极环加成反应在由供体-受体
环氧乙烷和醛生成的无环羰基叶立德之间进行。芳香族和脂肪族醛都可以用作亲偶极体,提供具有高非对映选择性和对映选择性的顺式-
1,3-二氧戊环。在机理研究的基础上,假设单体手性 Ni(II) 配合物作为环加成的活性物质。高
水平的不对称诱导可以通过醛的协同异步endo Si面方法得到令人满意的解释。