α-Diazoacetates as Carbene Precursors: Metallosalen-Catalyzed Asymmetric Cyclopropanation
作者:Tsutomu Katsuki、Tatsuya Uchida
DOI:10.1055/s-2006-926448
日期:2006.5
Readily available α-diazo compounds have been shown to be efficient carbene precursors for asymmetric cyclopropanation using ruthenium(NO)-salen and cobalt-salen complexes, as catalysts. The stereoselectivity of the cyclopropanation depends on the metal ion, its valency, the structural and electronic nature of the salen ligand, and the apical ligand of the salen complex used. Both trans- and cis-selective asymmetric intermolecular cyclopropanation can be realized under mild conditions by using a suitable metallosalen complex. Furthermore, a wide range of alkenyl α-diazoacetates and the related alkenyl diazomethyl ketones undergo intramolecular cyclopropanation in a highly enantioselective manner by using various metallosalen complexes, easily prepared in a modular fashion, as catalyst.
可 readily 获得的 α-二叠氮化合物已被证明是有效的卡宾前体,可用于使用钌(NO)-沙伦和钴-沙伦复合物作为催化剂的非对称环丙烷化反应。环丙烷化的立体选择性取决于金属离子、其价态、沙伦配体的结构和电子性质,以及所使用的沙伦复合物的顶端配体。在温和条件下,使用合适的金属沙伦复合物,可以实现顺式和反式选择性的非对称分子间环丙烷化。此外,通过使用多种金属沙伦复合物作为催化剂,广泛的烯丙基 α-二叠氮乙酸酯和相关的烯丙基二叠氮甲基酮可以以高度对映选择性的方式进行分子内环丙烷化,这些催化剂可以通过模块化方法轻松制备。