One-pot synthesis of 5-sulfonamidopyrazole from terminal alkynes, sulfonyl azides and hydrozones
作者:Yao Li、Deng Hong、Yuanxun Zhu、Ping Lu、Yanguang Wang
DOI:10.1016/j.tet.2011.08.067
日期:2011.10
5-Sulfonamidopyrazoles were efficiently synthesized from terminal alkynes, sulfonylazides and hydrozones. The sequential reaction involves a copper-catalyzed three-component reaction, a Lewis acid-catalyzed electrocyclic reaction and a dehydrogenation.
An efficient and high-yielding one-pot synthesis of 3,5-disubstituted-1,2,4-oxadiazoles from indazole carboxylic acid methyl esters and amidoximes is described. In this study a series of novel 3,5-disubstituted-1,2,4-oxadiazoles (3a-d), (4a-d), (5a-d), (6a-d), (7a-d) were synthesized using amidoximes 2a-d and indazole carboxylic acid esters (3-6).
Stereospecific Copper(II)-Catalyzed Tandem Ring Opening/Oxidative Alkylation of Donor–Acceptor Cyclopropanes with Hydrazones: Synthesis of Tetrahydropyridazines
Aerobic copper(II)-catalyzed tandem ringopening and oxidative C–H alkylation of donor–acceptorcyclopropanes with bisaryl hydrazones is accomplished to produce tetrahydropyridazines, in which copper(II) plays dual role as a Lewis acid as well as redox catalyst. The reaction is stereospecific, and optically active cyclopropanes can be reacted with high optical purities (89–98% enantiomeric excess)
novel efficient tandem reaction of hydrazones and α-bromo ketones is reported for the preparation of 1,3,5-trisubstituted pyrazoles by visible light catalysis. In this system, the monosubstituted hydrazones show wonderful reaction activity with alkyl radicals, generated from α-bromo ketones. A radical addition followed by intramolecular cyclization affords the important pyrazole skeleton in good to
REGENERATION OF CARBONYL COMPOUNDS FROM OXIMES, PHENYLHYDRAZONES,<i>p</i>-NITROPHENYLHYDRAZONES, AND SEMICARBAZONES BY QUINOLINIUM DICHROMATE UNDER NONAQUEOUS CONDITIONS
Treatment of oximes, phenylhydrazones, p-nitrophenyl-hydrazones, and semicarbazones with quinolinium dichromate (QDC) affords the corresponding carbonylcompounds in high yields under mild conditions.