Copper-Catalyzed Isomerization and Cyclization of<i>E</i>/<i>Z</i>-<i>o</i>-Haloaryl<i>N</i>-Sulfonylhydrazones: Convenient Access to 1<i>H</i>-Indazoles
作者:Xue-Qing Zhu、Shuai Mao、Dong-Dong Guo、Bin Li、Shi-Huan Guo、Ya-Ru Gao、Yong-Qiang Wang
DOI:10.1002/cctc.201601243
日期:2017.3.20
application in a broad range of chemical transformations. Generally, this isomerization can be realized either photochemically or thermally. A new isomerization approach is presented, namely a copper‐catalyzed C=N double bond isomerization of hydrazones, which is followed by an efficient intramolecular C−N coupling reaction, providing an unprecedented catalytic approach for the synthesis of 1H‐indazoles
Tandem Reaction of Propargyl Alcohol and <i>N</i>-Sulfonylhydrazone: Synthesis of Dihydropyrazole and Its Utility in the Preparation of 3,3-Diarylacrylonitrile
作者:Yuanxun Zhu、Shan Wen、Guangwei Yin、Deng Hong、Ping Lu、Yanguang Wang
DOI:10.1021/ol201203g
日期:2011.7.15
An efficient and straightforward strategy for the synthesis of 4-methylene-1-(phenylsulfonyl)-4,5-dihydro-1H-pyrazole from propargyl alcohol and N-sulfonylhydrazone is described. N-Sulfonyl allenamide is postulated to be the key intermediate for this tandem transformation.
Sterically Shielded, Stabilized Nitrile Imine for Rapid Bioorthogonal Protein Labeling in Live Cells
作者:Peng An、Tracey M. Lewandowski、Tuğçe G. Erbay、Peng Liu、Qing Lin
DOI:10.1021/jacs.8b00126
日期:2018.4.11
position of the N-aryl ring of diaryltetrazoles-precursors of nitrile imines, we discovered a sterically shielded nitrile imine that favors the 1,3-dipolar cycloaddition over the competing nucleophilic addition. The photogenerated nitrile imine exhibits an extraordinarily long half-life of 102 s in aqueous medium, owing to its unique molecular shape that hinders the approach of a nucleophile as shown by
highly chemoselective O-alkylation reaction is the use of potassium enolate of 1,3-diketones as the base as well as the nucleophile in a highly polar-aprotic solvent at moderate temperature. These vinyl ethers are subsequently converted into novel oxoisochromene derivatives via Pd-catalyzed intramolecular arylation reaction. A plausible mechanism of the chemoselective O-alkylation reaction is outlined.