1,3-Cycloaddition of nitrile oxides in ionic liquids. An easier route to 3-carboxy isoxazolines, potential constrained glutamic acid analogues
摘要:
Several improvements in the cycloaddition of carboethoxyformonitrile oxide (CEFNO) with different alkenes are observed in the ionic liquids [bmim][BF4] and [bmim][PF6]. The possibility of obtaining good yields of the corresponding isoxazolines opens the way towards parallel collections of glutamic acid (Glu) analogues. (C) 2003 Elsevier Science Ltd. All rights reserved.
Oxidize Amines to Nitrile Oxides: One Type of Amine Oxidation and Its Application to Directly Construct Isoxazoles and Isoxazolines
作者:Xiao-Wei Zhang、Xiao-Lin He、Nan Yan、Hong-Xing Zheng、Xiang-Guo Hu
DOI:10.1021/acs.joc.0c02281
日期:2020.12.4
A facile oxidative heterocyclization of commercially available amines and tert-butyl nitrite with alkynes or alkenes leading to isoxazoles or isoxazolines is described. The unprecedented strategy of the oxidation of an amine directly to a nitrile oxide was used in this cyclization process. This reaction is highly efficient, regiospecific, operationally simple, mild, and tolerant of a variety of functional
Oxidative and dehydrative cyclizations of nitroacetate esters with Mn(OAc)3
作者:Barry B Snider、Qinglin Che
DOI:10.1016/s0040-4020(02)00911-0
日期:2002.9
Reaction of α-unsubstituted nitroacetates with Mn(OAc)3 gives mixtures of isoxazolines, formed by dehydration to a nitrile oxide that undergoes cycloaddition, and isoxazoline oxides or cyclopropane, formed by oxidative cyclization. Oxidative cyclization is favored with electron-rich alkenes and cycloaddition with the nitrile oxide to give isoxazolines is favored with electron-poor alkenes. On the other
Acyclic nitronate olefin cycloaddition (ANOC): regio- and stereospecific synthesis of isoxazolines
作者:Liang Ma、Luyao Kou、Feng Jin、Xionglve Cheng、Suyan Tao、Gangzhong Jiang、Xiaoguang Bao、Xiaobing Wan
DOI:10.1039/d0sc05607c
日期:——
We report the first demonstrations of intra- and intermolecular acyclic nitronate olefin cycloaddition (ANOC) reactions that enable the highly efficient syntheses of isoxazolines bearing various functional groups. This general approach to accessing γ-lactone fused isoxazolines was hitherto unprecedented. The room temperature transformations reported herein exhibit wide substrate scopes, as evidenced
Cycloaddition reactions of nitrosoalkenes, azoalkenes and nitrile oxides mediated by hydrotalcite
作者:Americo Lemos、João Paulo Lourenço
DOI:10.3998/ark.5550190.0011.515
日期:——
Mg:Al 3:1 hydrotalcite (Ht), used in catalytic quantities, promotes the generation of nitrosoalkenes, azoalkenes and nitrile oxides. These can be intercepted in situ by heterocycles and olefins in [4+2] and [3+2] cycloadditionreactions, producing dihydro-1,2-oxazines, tetrahydropyridazines and isoxazolines. The regeneration and reuse of Ht without loss of activity and the absence of organic solvent