The use of Ti(Ot-Bu)4, or related bulky titanium(IV) alkoxides, as cocatalysts instead of Ti(Oi-Pr)4 in the enantioselective addition of dimethylzinc to aldehydes in the presence of the catalyst 2 (8 mol%) leads to a dramatic improvement of the enantioselectivity (0%ee to 93%ee). The scope and the limitations of this effect are described.
使用的Ti(O的吨-Bu)4,或相关的笨重的
钛(IV)醇盐,作为助催化剂的
钛代替(O我-Pr)4在对映选择性加成二甲基
锌在催化剂的存在下的醛2(8 mol%)导致对映选择性的显着提高(0%ee至93%ee)。描述了这种效果的范围和局限性。