An Intramolecular Wittig Approach toward Heteroarenes: Synthesis of Pyrazoles, Isoxazoles, and Chromenone-oximes
作者:Pankaj V. Khairnar、Tsai-Hui Lung、Yi-Jung Lin、Chi-Yi Wu、Srinivasa Rao Koppolu、Athukuri Edukondalu、Praneeth Karanam、Wenwei Lin
DOI:10.1021/acs.orglett.9b01395
日期:2019.6.7
α-Halohydrazones/ketoximes are transformed into trisubstituted pyrazoles/disubstituted isoxazoles by treatment with phosphine, acyl chloride, and a base. Mechanistic investigations revealed the in situ formation of azo/nitroso olefin intermediates which underwent a tandem phospha-Michael/N- or O-acylation/intramolecular Wittig reaction to afford the heteroarenes in moderate to good yields. Further
通过用膦,酰氯和碱处理,将α-卤代azo酮/酮肟转化为三取代的吡唑/二取代的异恶唑。机理研究揭示了偶氮/亚硝基烯烃中间体的原位形成,该中间体进行了串联的磷酰基-Michael / N-或O-酰化/分子内Wittig反应,以中等至良好的产率提供了杂芳烃。此外,α-卤代毒素的适当官能化和条件的改变允许色酮肟和重排的异恶唑的化学选择性合成,从而实现了面向多样性的合成。