Synergistic Pd/Cu-catalysed regio- and stereoselective borylation of allenylic carbonates.

A simple Pd/Cu-catalyzed borylation of allenylic carbonates with B 2 Pin 2 was developed using a cheap P(OEt) 3 ligand. Under mild neutral conditions, 2-boryl 1,3-butadienes were obtained selectively in moderate to high yields. Furthermore, the use of different diboron reagents was also feasible in the reaction.