The use of enaminones and enamines as effective synthons for MSA-catalyzed regioselective synthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles
In the present work, an efficient regioselectivesynthesis of 1,3,4-tri- and 1,3,4,5-tetrasubstituted pyrazoles via a methanesulfonic acid (MSA)-catalyzed reaction of hydrazones with enaminones or enamines is reported. Mechanistically, the formation of the title compounds involves the [2+3] cycloaddition of hydrazones with enaminones or enamines followed by aromatization with acid and oxygen. This
The AlCl3-promoted reactions of cycloalkanones with hydrazones are described. This approach represents a mild and operationally simple method to access 2,3-diaryl-4,5,6,7-tetrahydro-1H-indazoles and their analogues in good to moderate yields.
A robust protocol for Pd(ii)-catalyzed C-3 arylation of (1H) indazoles and pyrazoles: total synthesis of nigellidine hydrobromide
作者:Mengchun Ye、Andrew J. F. Edmunds、James A. Morris、David Sale、Yejia Zhang、Jin-Quan Yu
DOI:10.1039/c3sc50184a
日期:——
indazole and pyrazoles are privileged structural motifs in agrochemicals and pharmaceuticals. C-3 C-H arylation of (1H) indazole and pyrazole has been a significant challenge due to the poor reactivity of the C-3 position. Herein, we report a practical Pd(II)/Phen catalyst and conditions for direct C-3 arylation of indazole and pyrazole with ArI or ArBr without using Ag additives as halide scavengers. The
C<sub>sp<sup>3</sup></sub>–C<sub>sp<sup>3</sup></sub> Bond Cleavage in the Palladium-Catalyzed Aminohydroxylation of Allylic Hydrazones Using Atmospheric Oxygen as the Sole Oxidant
作者:Yu-Chen Chen、Ming-Kui Zhu、Teck-Peng Loh
DOI:10.1021/acs.orglett.5b01127
日期:2015.6.5
A C–C bond cleavage was observed in the palladium-catalyzed aminohydroxylation of allylic hydrazones, using atmospheric oxygen as the soleoxidant. This reaction could also proceed in a one-pot manner, starting from keto-alkene compounds and phenylhydrazine.