Cobalt catalyst (5 mol%, 10 ??mol, 8.6 mg) and magnets were added to the dried reaction vial and the vial was capped using a stopper with a rubber septum. The air in the reaction vial was displaced with argon, and tetrahydrofuran (2.0 mL), alkenone (1 equiv., 0.2 mmol), and pinacolborane (2 equiv., 0.4 mmol, 58 ??L) were added sequentially to the mixture. The vials were exposed to a blue LED overnight. At the end of the reaction, the solution was diluted with ether, the mixture was washed twice with distilled water, the combined aqueous layer was extracted twice with ether, and finally the combined organic layer was washed with brine. The resulting mixture was dried with anhydrous magnesium sulfate, and the mixture was filtered to remove the magnesium sulfate; the mixture was concentrated under vacuum, and the crude product was purified by column chromatography (0-10% ethyl ether in pentane) to give the target product 4,4-dimethylcyclohexanone.
