Copper-catalyzed stereoselective alkylhydrazination of alkynes†
An unprecedented Cu-catalyzed stereoselective alkylhydrazination reaction involving terminal alkynes, azocarboxylic esters as a nitrogen source, and dimethyl 2,2′-azobis(2-methylpropionate) and its analogues as a carbon source is presented here. This protocol provides direct access to tri-substituted (E)-alkenyl-hydrazines with good regio- and stereoselectivity under mild conditions. The transformation proceeds without an external oxidant or additives and shows good functional group tolerance. The alkenylhydrazine products could be easily converted into valuable 1,4-dicarbonyl and allyl carboxylic derivatives.