Cu-Catalyzed solvent-free, pot-economic synthesis of 1,3-dynes from 1,1-dibromoalkenes in the presence of DBU•H2O

Abstract

An efficient synthesis of 1,3-diynes directly from 1,1-dibromoalkenes has been achieved by utilizing hydrated 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU.H2O) as a sole reagent and a catalyst CuI. In general, 1,3-diynes were synthesized from corresponding terminal alkynes, which in turn were obtained from 1,1-dibromoalkenes. The DBU.H2O allowed the synthesis of 1,3-diynes not only in a pot-efficient manner but also under solvent-free conditions at ambient temperature. A plausible mechanism is proposed via 1-bromoalkynes intermediate instead of terminal alkynes.