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
A general access to isoxazoles with outstanding functional group compatibility from the readily available ynones using trimethylsilyl azide as an amino surrogate under exceptionally simple conditions is described.