Carbene-catalyzed LUMO activation of alkyne esters for access to functional pyridines
作者:Chengli Mou、Jichang Wu、Zhijian Huang、Jun Sun、Zhichao Jin、Yonggui Robin Chi
DOI:10.1039/c7cc08039e
日期:——
A carbene-catalyzed LUMOactivation of α,β-unsaturated alkyne esters is reported. This catalytic process allows for effective reactions of alkyne esters with enamides to synthesize functional pyridines via simple protocols. A previously unexplored unsaturated alkyne acyl azolium intermediate is involved in the key step of the reaction.
An enantioselective Pd-catalyzed intramolecular desymmetrizing cycloisomerization of N-(cyclopent-3-en-1-yl)propiolamides has been developed by employing a new chiral phosphoramidite ligand. A series of structurally unique bridged azabicycles are achieved in moderate to excellent yields with good E/Z selectivity and high enantioselectivity. Synthetic transformations are conducted to demonstrate the
2,5-Diarylisothiazolone: novel inhibitors of cytokine-induced cartilage destruction
作者:Stephen W. Wright、Joseph J. Petraitis、Bruce Freimark、John V. Giannaras、Michael A. Pratta、Susan R. Sherk、Jean M. Williams、Ronald L. Magolda、Elizabeth C. Arner
DOI:10.1016/0968-0896(96)00053-3
日期:1996.6
A series of 2,5-diarylisothiazolones is reported that inhibit the IL-lp-induced breakdown of bovine nasal septum cartilage in an organ culture assay. The synthesis and preliminary SAR of these compounds are described. These compounds represent a novel, nonpeptide lead series approach to the mediation of the chronic cartilage breakdown associated with arthritic disease. These compounds are relatively resistant to reductive metabolism by liver microsomal preparations and appear to inhibit cartilage breakdown by interfering with the proteolytic activation of matrix metalloproteinases. Copyright (C) 1996 Elsevier Science Ltd
Convergent and Rapid Assembly of Substituted 2-Pyridones through Formation of <i>N</i>-Alkenyl Alkynylamides Followed by Gold-Catalyzed Cycloisomerization
A new method for the convergent and rapid assembly of substituted 2-pyridones was developed through the formation of N-alkenyl alkynylamides (amide-linked 1,5-enynes) by N-acylation of imines with alkynoyl chlorides and the subsequent cationic Au(I)/PPh3-catalyzed cycloisomerization.
Gold-Catalyzed Cyclization and Subsequent Arylidene Group Transfer of <i>O</i>-Propioloyl Oximes
作者:Itaru Nakamura、Masashi Okamoto、Masahiro Terada
DOI:10.1021/ol100581m
日期:2010.6.4
Gold-catalyzed cyclizations of O-propioloyl oximes via C-N bond formation followed by arylidene group transfer were successfully carried out to afford the corresponding 4-arylideneisoxazol-5(4H)-ones in good to excellent yields. As an example, (E)-benzaldehyde O-3-phenylpropioloyl oxime (1a) was reacted in acetonitrile at 25 degrees C in the presence of Au(PPh(3))NTf(2) (5 mol %) to give 4-benzylidene-3-phenylisoxazol-5(4H)-one (2a) in 90% yield. On the basis of crossover experiments, the arylidene "migration" was shown to proceed in an intermolecular manner.