Regioselective Synthesis of 1,3,5-Tri- and 1,3,4,5-Tetrasubstituted Pyrazoles from N-Arylhydrazones and Nitroolefins
摘要:
[GRAPHICS]Two general protocols are developed for the regioselective synthesis of 1,3,5-tri- and 1,3,4,5-tetrasubstituted pyrazoles by the reaction of electron-deficient N-arylhydrazones with nitroolefins. Studies on the stereochemistry of the key pyrazolidine intermediate suggest a stepwise cycloaddition mechanism.
Base‐Mediated Generation of Ketenimines from Ynamides: Addition of Hydrazones to Give Acetimidohydrazides**
作者:Capucine Mahe、Agathe C. A. D'Hollander、Kevin Cariou
DOI:10.1002/ejoc.202200028
日期:2022.5.13
The addition of hydrazones onto the central carbon of the ketenimines generated in situ from N-Boc ynamides is reported. This reaction takes place under basic conditions and heating, to generate the N-arylketenimines, and gives access to a variety of acetimidohydrazides.