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. An efficient copper-catalyzed stereoselective alkylhydrazination of alkynes, leading to tri-substituted ( E )-alkenylhydrazines, has been developed.