Synthesis of Allenes via Nickel-Catalyzed Cross-Coupling Reaction of Propargylic Bromides with Grignard Reagents

We describe a convenient method for the synthesis of terminal allenes from cross-coupling of propargylic bromide with Grignard reagent. The reaction of propargylic bromide with 1.2 equivalents of Grignard reagent mediated by Ni(acac)2 (2 mol%) and Ph3P (4 mol%) in THF may produce terminal allenes in good yields and high regioselectivities at room temperature.