General and Selective Head-to-Head Dimerization of Terminal Alkynes Proceeding via Hydropalladation Pathway
作者:Claire Jahier、Olga V. Zatolochnaya、Nickolay V. Zvyagintsev、Valentine P. Ananikov、Vladimir Gevorgyan
DOI:10.1021/ol3010936
日期:2012.6.1
A general highly regio- and stereoselective palladium-catalyzed head-to-headdimerization reaction of terminal acetylenes is presented. This methodology allows for the efficient synthesis of a variety of 1,4-enynes as single E stereoisomers. Computational studies reveal that this dimerization reaction proceeds via the hydropalladation pathway.
E-conjugated enynes bearing an acetal function on the allylic or the homoallylic position or/and on the propargylic or the homopropargylic position were conveniently obtained at room temperature in DMF via cross coupling of the corresponding vinyltins with 1-bromoalk-1-ynes in the or Pd(II) catalysts.
Carboxylate Switch between Hydro- and Carbopalladation Pathways in Regiodivergent Dimerization of Alkynes
作者:Olga V. Zatolochnaya、Evgeniy G. Gordeev、Claire Jahier、Valentine P. Ananikov、Vladimir Gevorgyan
DOI:10.1002/chem.201402809
日期:2014.7.28
regiodivergent palladium‐catalyzed dimerization of terminalalkynes is presented. Employment of N‐heterocyclic carbene‐based palladium catalyst in the presence of phosphine ligand allows for highly regio‐ and stereoselective head‐to‐head dimerization reaction. Alternatively, addition of carboxylate anion to the reaction mixture triggers selective head‐to‐tail coupling. Computational studies suggest that reaction