The cycloaddition of nitrilimines with 1,2-dibenzoylethylenes gave an unexpected 1,3-diaryl-4-benzoylpyrazole and benzoic acid, along with an expected cycloadduct, 1,3-diaryl-4,5-dibenzoyl-2-pyrazoline, and its dehydrogenated product, 1,3-diaryl-4,5-dibenzoylpyrazole. The elimination of the benzoyl group from the pyrazoline followed by dehydrogenation was shown to be the course of the unusual reaction
Synthesis of 4-Acylpyrazoles from Saturated Ketones and Hydrazones Featured with Multiple C(sp<sup>3</sup>)–H Bond Functionalization and C–C Bond Cleavage and Reorganization
作者:Miaomiao Tian、Xiaonan Shi、Xinying Zhang、Xuesen Fan
DOI:10.1021/acs.joc.7b01013
日期:2017.7.21
paper, an efficient and convenient one-pot synthesis of diversely substituted 4-acylpyrazole derivativesvia copper-catalyzed one-pot cascade reactions of saturated ketones with hydrazones is reported. Mechanistically, the formation of the title compounds involves the in situ formation of an enone intermediate through the dehydrogenation of a saturated ketone and the [2 + 3] cyclization of the enone