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.