An asymmetric synthesis of 5-halomethyl pyrazolines and isoxazolines which bear a tertiary stereocenter by catalytic halocyclization of β,γ-unsaturatedhydrazones and ketoximes is described. By using Brønsted acids of anionic chiral Co(III) complexes as catalysts, a variety of chiral 5-halomethyl pyrazolines and isoxazolines were obtained in good yields with high enantioselectivities (up to 99% yield
Hypervalent Iodine–Catalyzed Cycloaddition of Nitrile Oxides to Alkenes
作者:Changbin Xiang、Tingting Li、Jie Yan
DOI:10.1080/00397911.2013.834364
日期:2014.3.4
convenient method for preparation of isoxazolines was developed by a catalytic cycloaddition of nitrileoxides generated in situfrom aldoximes to alkenes in the presence of a catalytic amount of iodobenzene. In this protocol, iodobenzene was first oxidized into the hypervalent iodine intermediate by m-chloroperbenzoic acid, which then transformed aldoximes into nitrileoxides, and a 1,3-dipolar cycloaddition
An environmentally benign synthesis of isoxazolines and isoxazoles mediated by potassium chloride in water
作者:Liuquan Han、Bijun Zhang、Min Zhu、Jie Yan
DOI:10.1016/j.tetlet.2014.02.118
日期:2014.4
An effective and environmentally benign procedure for the synthesis of isoxazolines and isoxazoles has been developed by a cycloaddition of nitrile oxides with alkenes or alkynes in water. In this approach, potassium chloride is first oxidized into chlorine in water by the environmentally friendly oxidant Oxone®, then aldoximes are oxidized into nitrile oxides by the in situ generated hypochlorous
Oxime-Mediated Oxychlorination and Oxybromination of Unactivated Olefins
作者:Kui-Yong Dong、Hai-Tao Qin、Feng Liu、Chen Zhu
DOI:10.1002/ejoc.201403538
日期:2015.3
An oxime-mediatedoxychlorination and oxybromination of unactivatedolefins relying on palladium catalysis has been developed. A wide range of chlorinated and brominated isoxazolines has been synthesized in moderate to good yields. To demonstrate the value of the method, the brominated isoxazoline has been further converted to other useful synthetic feedstock.