Oxidation of olefins by palladium(II). 18. Effect of reaction conditions, substrate structure and chiral ligand on the bimetallic palladium(II) catalyzed asymmetric chlorohydrin synthesis
作者:Arab K El-Qisairi、Hanan A Qaseer、Patrick M Henry
DOI:10.1016/s0022-328x(02)01580-2
日期:2002.8
The effect of electronic factors, solvent composition, identity of the chiral bidentate, and olefin structure on the yields and enantioselectivities of the asymmetric chlorohydrin synthesis were investigated. Electronic effects on the chlorohydrin reaction were tested by oxidation of phenyl allyl ether p-substituted by H, Cl, CH3O and CN. All species gave same similar yields and enantioselectivities
研究了电子因素,溶剂组成,手性双齿的身份以及烯烃结构对不对称氯醇合成的收率和对映选择性的影响。通过H,Cl,CH 3 O和CN对-取代的苯基烯丙基醚的氧化,测试了对氯代醇反应的电子效应。所有物种都具有相同的相似产率和对映选择性,表明电子效应并不重要。改变THF-H 2 O混合物的溶剂组成表明,最佳溶剂混合物包含超过85%的THF。加入变异氯[Cl -]表明,为了获得高产率和%ee,添加的氯化物必须大于0.2M。在理想条件下,来自苯基烯丙基醚的氯醇的对映选择性大于90%ee。乙烯基乙酸,丙烯酸甲酯和反式-肉桂醛在通常的反应条件下不反应,而2-羟基-3-丁烯和乙酸烯丙酯的ee's低于苯基烯丙基醚。苯乙烯和α-甲基苯乙烯的反应速率相当,但后者的ee较低。(2,6-二异丙基)苯基烯丙基醚和2-羟基-3-丁烯给出高的ee,表明空间位阻不是主要因素。除DACH外,所有测试的手性桥联配体均给出令人满意的