一种新型2,5-二甲基-2,4-己二烯不对称环丙烷化原位催化体系

以（ － ）１ Ｒ,２ Ｓ２氨 基１ ,２二苯 基乙 醇 作为 手性 源, 与取 代 水杨 醛 缩合 制 备 了系 列 手性 Ｓｃｈｉｆｆ 碱配 体,考察 了该类配体的二价铜配合物及配体与 Ｃｕ（ Ｃ Ｈ３ Ｃ Ｎ）４ Ｃｌ Ｏ４ 组成的原位 体系对２ ,５二甲基２ ,４己二烯与 重氮乙酸 Ｌ薄 荷酯的环丙烷化反应的催化作用． 结果表明, Ｃｕ（Ⅱ） 配合物尽管具有较高的催化活性,但几乎没有光 学选择性,而原 位体系 则表 现出极 高的 催化活 性和 一定的 光学选择性,化学收率为９０３ ％ , 顺 式体ｅ ．ｅ ．值达到３０ ％     

手性铜(Ⅱ)-席夫碱配合物催化苯乙烯不对称环丙烷化反应

Twelve chiral copper(Ⅱ) Schiff base complexes, derived from (R) (+) 2 amino 1,1 diaryl 1 propanol with substituted salicylaldehydes, were examined as a catalyst for asymmetric cyclopropanation of styrene with ethyl diazoacetate. It was found that the substituents at 3 and 5 positions of salicylaldehyde in the ligands had great effects on catalytic activity and enantioselectivity of the catalyst. The complex with strong electron withdrawing group (NO 2) at 5 position and the smallest stereo hinder (H) at 3 position of salicylaldehyde showed highly catalytic activity and enantioselectivity, up to ee =87 4% for trans and ee =82 8% for cis isomers respectively, and the ratio 39/61 of cis to trans isomers was obtained at 40 ℃ with 1,2 dichloroethane as solvent.