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
Nitrolic acids are prepared in good yields from primary nitroalkanes or primary alkyl bromides. Upon heating in THF, they afford the corresponding nitrileoxides under neutral conditions. In the presence of dipolarophiles, isoxazoles are obtained in yields up to 95%. For the less stable alkoxycarbonyl- and arylnitrolic acids the crude nitrolic acids can be directly engaged in the cycloaddition reaction
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.
Effect of Aqueous Polyethylene Glycol on 1,3-Dipolar Cycloaddition of Benzoylnitromethane/Ethyl 2-Nitroacetate with Dipolarophiles: Green Synthesis of Isoxazoles and Isoxazolines
作者:R. Gangadhara Chary、G. Rajeshwar Reddy、Y. S. S. Ganesh、K. Vara Prasad、Akula Raghunadh、T. Krishna、Soumita Mukherjee、Manojit Pal
DOI:10.1002/adsc.201300712
日期:2014.1.13
A 1:1 mixture of water‐polyethyleneglycol (PEG) facilitated the 1,3‐dipolar cycloaddition of benzoylnitromethane/ethyl 2‐nitroacetate with terminal alkynes or alkenes leading to isoxazoles or isoxazolines under green conditions. The methodology is free from the use of any base, catalyst, dehydrating agent or hazardous solvent.