A mixture of imines and bis(pinacolato)diboron in water furnished the enantioenriched imines after oxidation using a chiral copper(ii) complex as the catalyst.
Substrate Photoswitching for Rate Enhancement of a Organocatalytic Cyclization Reaction
作者:Matej Žabka、Ruth M. Gschwind
DOI:10.1002/ejoc.202200048
日期:2022.7.14
high catalyst loadings, as the processes are sluggish and complex equilibria are involved. Here, in situ light irradiation with a specific wavelength inside NMR is applied to increase reactionrates of hydrazone cyclization. This enhancement was achieved by isomerizing the substrate to the reactive configuration.
An Oxone-mediated transition-metal-free oxidative C-N bond formation has been achieved for the regio-selective synthesis of substituted pyrazoles. The reactions accompany the chelation-controlled ortho-oxidation of N-substituted aromatic ring to provide phenol derivatives in some cases. This method displays a facile access to diverse range of substituted pyrazoles from readily accessible hydrazones. (C) 2015 Elsevier Ltd. All rights reserved.
THE PREPARATION OF 3-(2-PHENYLETHENYL)-1<i>H</i>-PYRAZOLES FROM DILITHIATED (3<i>E</i>)-4-PHENYL-3-BUTEN-2-ONE HYDRAZONES
作者:Stefan J. Pastine、Wayne Kelley、Jennifer J. Bear、J. Nathan Templeton、Charles F. Beam
DOI:10.1081/scc-100000580
日期:2001.1
The phenyl-, carbomethoxy-, and carboethoxy-hydrazones of (3 E)-4-phenyl-3-buten-2-one [benzalacetone] were treated with excess lithium diisopropylamide, and the resulting 1,4-dianions were condensed with several aromatic esters, followed by acid cyclization of C-acylated intermediates, to afford substituted 3-(2-phenylethenyl)-1H-pyrazoles [3-styryl-pyrazoles].
BALACHANDRAN K. S.; GEORGE M. V., TETRAHEDRON <TETR-AB>, 1975, 31, NO 11-12, 1491-1499