A novel protocol for the synthesis of α-aryl nitriles has been successfully achieved via a copper-catalyzed cyanation of N-tosylhydrazones employing thiocyanate as the source of cyanide. The features of this method include a convenient operation, readily available substrates, low-toxicity thiocyanate salts, and a broad substrate scope.
Pyrrolo-imidazo[1,2-<i>a</i>]pyridine Scaffolds through a Sequential Coupling of <i>N</i>-Tosylhydrazones with Imidazopyridines and Reductive Cadogan Annulation, Synthetic Scope, and Application
作者:Kena Zhang、Abderrahman El Bouakher、Helene Levaique、Jerome Bignon、Pascal Retailleau、Mouad Alami、Abdallah Hamze
DOI:10.1021/acs.joc.9b02018
日期:2019.11.1
of 3-phenyl-1H-pyrrolo-imidazo[1,2-a]pyridine backbone is described. The reaction starts from the coupling between N-tosylhydrazones and 2-chloro-3-nitroimidazo[1,2-a]pyridines leading to the formation of 3-nitro-2-(arylvinyl)imidazo[1,2-a]pyridinederivatives. Optimization of Cadogan-reductive conditions allowed the conversion of the obtained nitro derivative to a new scaffold of the type 3-aryl-
Copper-Catalyzed Direct Benzylation or Allylation of 1,3-Azoles with <i>N</i>-Tosylhydrazones
作者:Xia Zhao、Guojiao Wu、Yan Zhang、Jianbo Wang
DOI:10.1021/ja111249p
日期:2011.3.16
Cu-catalyzed cross-coupling of N-tosylhydrazones with 1,3-azoles leads to the direct C-H benzylation or allylation. Cu carbene migratory insertion is proposed to play the key role in this transformation.
Selective construction of 2-substituted benzothiazoles from o-iodoaniline derivatives S8 and N-tosylhydrazone via a copper-promoted [3 + 1 + 1]-type cyclization reaction has been realized. In the protocol, the carbon atom on N-tosylhydrazone could be regulated to construct benzothiazole by changing the reaction system. Furthermore, the transformation has achieved the construction of multiple carbon-heteroatom
situ from tosylhydrazones. In addition, by using chiral dirhodium catalysts, we also achieved an asymmetric version of the reaction with good to excellent enantioselectivities (up to 98:2 e.r.). This is the first enantioselective heteroatom-hydrogen bond insertion reaction to use unstabilized diazo compounds as carbene precursors. The protocol exhibited good functional group tolerance and could be carried