Hydrochloric Acid → (3,3,3-Trifluoroprop-1-en-2-yl)boronic acid

Participants

Reaction Conditions

Reaction Steps

To magnesium turnings (5.83 g, 0.24 mol) in tetrahydrofuran (400 ml) was added dropwise trimethyl borate (68.13 ml, 0.6 mol). The reaction mixture was cooled to 0° C. and 2-bromo-3,3,3-trifluoropropene (20.75 ml, 0.2 mol) was added dropwise. The reaction mixture was then allowed to warm to room temperature and stirred under nitrogen overnight. The reaction mixture was again cooled to 0° C. and hydrochloric acid (5M, 200 ml) was added dropwise, ensuring that the temperature of the solution remained below 10° C. The reaction mixture was then stirred under nitrogen for 48 h. To the reaction mixture was added diethyl ether (100 ml) and water (200 ml) to give two phases. The aqueous layer was separated and extracted with diethyl ether (100 ml). The combined organic phases were washed with water (100 ml), dried (MgSO4) and concentrated in vacuo. To the residue was added cyclohexane (50 ml), resulting in precipitate formation. The precipitate was isolated by decanting the solution, washed with cyclohexane, and dried in vacuo to give Preparation 59 (2.62 g, 0.02 mol) as a white solid.

Provenance & Evidence