Chromium‐Catalyzed Selective Dimerization/Hydroboration of Allenes to Access Boryl‐Functionalized Skipped (E,Z)‐Dienes

A chromium‐catalyzed dimerization/hydroboration of allenes is developed to access synthetically versatile boryl‐functionalized skipped dienes with a catalyst generated in situ from CrCl2 and a pyridine‐2,6‐diimine ligand mesPDI. A variety of allenes reacted with pinacolborane (HBpin) to afford the corresponding boryl‐functionalized (E,Z)‐1,4‐dienes in high yields and with excellent selectivity. Electron paramagnetic resonance (EPR) spectroscopic studies suggest that this chromium‐catalyzed reaction probably proceeds through a chromium(I) hydride intermediate. A chromium‐catalyzed dimerization/hydroboration of allenes is developed to access synthetically versatile boryl‐functionalized skipped dienes with a catalyst generated in situ from CrCl2 and a pyridine‐2,6‐diimine ligand mesPDI. A variety of allenes reacted with pinacolborane (HBpin) to afford the corresponding boryl‐functionalized (E,Z)‐1,4‐dienes in high yields and with excellent selectivity.