Practical Enantioselective Arylation and Heteroarylation of Aldehydes with In Situ Prepared Organotitanium Reagents Catalyzed by 3-Aryl-H<sub>8</sub>-BINOL-Derived Titanium Complexes
作者:Ami Uenishi、Yuya Nakagawa、Hironobu Osumi、Toshiro Harada
DOI:10.1002/chem.201203946
日期:2013.4.8
A highly efficient and practical method for the catalytic enantioselective arylation and heteroarylation of aldehydes with organotitanium reagents, prepared in situ by the reaction of aryl‐ and heteroaryllithium reagents with ClTi(OiPr)3, is described. Titanium complexes derived from DPP‐H8‐BINOL (3 d; DPP=3,5‐diphenylphenyl) and DTBP‐H8‐BINOL (3 e; DTBP=3,5‐di‐tert‐butylphenyl) exhibit excellent catalytic
描述了一种通过有机钛试剂催化醛的对映选择性芳基化和杂芳基化的高效实用方法,该方法是通过芳基和杂芳基锂试剂与ClTi(O i Pr)3反应原位制备的。从DPP-H的钛络合物8 -BINOL(3 d ; DPP = 3,5-二苯基苯基)和DTBP-H 8 -BINOL(图3e ; DTBP = 3,5-二-叔叔丁基苯基)在转化的对映选择性和周转效率方面表现出出色的催化活性,在低催化剂负载量(0.2-2 mol%)下提供高对映选择性的二芳基,芳基杂芳基和二杂芳基甲醇衍生物。反应开始于各种芳基和杂芳基溴,通过与n BuLi的Br / Li交换,将它们转化为有机锂中间体,从而使从市售起始原料中直接获得一系列对映体富集的醇类成为可能。通过使用市售的2-噻吩基锂在THF中可以对映选择性地合成各种2-噻吩基甲醇。该反应可以在0.5mol%催化剂负载下以10mmol规模进行,证明了其制备用途。