ω-Chloroisonitrosoacetophenone was treated with ethylenic and acetylenic dipolarophiles to afford 3-benzoylisoxazolinines and -isoxazoles, respectively. With m-nitrobenzaldoxime or m-nitrobenzonitrile, it yielded 3-benzoyl-5-(m-nitrophenyl)-1,2,4-oxadiazole. The phenylhydrazones of the 3-benzoylisoxazole and -oxodiazole thus produced were converted to the corresponding 1,2,3-triazoles thermally or
Copper Nitrate Mediated Regioselective [2+2+1] Cyclization of Alkynes with Alkenes: A Cascade Approach to Δ<sup>2</sup>-Isoxazolines
作者:Mingchun Gao、Yingying Li、Yuansheng Gan、Bin Xu
DOI:10.1002/anie.201503393
日期:2015.7.20
An efficient method for the regioselective synthesis of pharmacologically relevant polysubstituted Δ2‐isoxazolines is based on the copper‐mediated direct transformation of simple terminal alkynes and alkenes. The overall process involves the formation of four chemical bonds with inexpensive and readily available copper nitrate trihydrate as a novel precursor of nitrile oxides. The reaction can be easily
Aromatic and aliphatic nitrile oxides are generated by the oxidation of α-hydroxyimino carboxylic acid with ammoniumhexanitratocerate(IV). They react with olefinic and acetylenic dipolarophiles to give the corresponding cycloaddition products in good yield. The oxidation of α-oxo aldoximes also affords α-oxo carbonitrile oxides.