Borylation of Skipped Dienes

CuCl (0.98 mg, 10 mol%, 0.01 mmol), bis(pinacolato)diboron (60.9 mg, 1.2 equiv, 0.24 mmol), and Xantphos (138.8 mg, 10 mol%, 0.01 mmol) were placed in an oven‐dried reaction vial. The vial was sealed with a screw cap containing a Teflon‐coated rubber septum. The vial was connected to a vacuum/nitrogen manifold through a needle, evacuated, and backfilled with nitrogen and THF (0.24 mL, 1 M). KO^tBu (26.9 mg, 1.2 equiv, 0.24 mmol) in THF (0.24 mL, 1 M) was added to the vial through the rubber septum. Then, the borylated (E) skipped dienes (1 equiv, 0.2 mmol) in THF (0.2 mL, 1 M) were added dropwise at 30 °C for 16 h. After the reaction was complete, 1 mL MeOH was added and stirred for 10 min and the reaction mixture was filtered over Celite. The organic extracts were then concentrated under vacuum and the NMR yield was calculated through comparison to an internal standard (naphthalene). The crude residue was purified by silica gel flash chromatography to obtain the desired product.