Computational study on catalyst-free BCl3-promoted chloroboration of carbonyl compounds.

DFT calculations were performed to investigate the possible reaction mechanisms underlying catalyst-free chloroboration reactions of carbonyl compounds with BCl3. The interaction between BCl3 and the C[double bond, length as m-dash]O moiety of carbonyl compounds is a two-step reaction. In the first step, B of BCl3 forms a bond with the O of the C[double bond, length as m-dash]O moiety, followed by the 1,3-Cl migration process from BCl3 to the C of the carbonyl group. To indicate the versatility of our synthetic methodology, a catalyst-free chloroboration of a variety of aldehydes and ketones with a broad range of electron-donating and electron-withdrawing groups with BCl3 was checked. According to DFT results, BCl3-induced chloroboration of aldehydes and ketones progressed under a kinetically favorable condition with <20 kcal mol-1 of activation free energy.