A new method to access β-keto-gem-diborylalkanes, by direct deoxygenative radical addition of aromatic carboxylic acids to gem-dibortlalkenes, is described. The reaction proceeds under mild photoredox catalysis and involves the photochemical C−O bond activation of aromatic carboxylic acids in the presence of PPh3. It generates an acyl radical, which further undergoes an additional reaction with gem-diborylalkenes to form an α-gem-diboryl alkyl radical intermediate, which then reduces to the corresponding anion, which after protonation, affords the β-keto-gem-diborylalkane product. Moreover, the same scenario has been extended to the vinyl boronic esters, for example, gem-(Ar, Bpin)-alkenes, and gem-(Alkyl, Bpin)-alkenes. Importantly, this protocol provides a general platform for the late-stage functionalization of bio-active and drug molecules containing a carboxylic acid group.
Bibliographical noteFunding Information:
This research was supported by a grant from the Israel Science Foundation (Grant No. 287/21). We thank Dr. Benny Bogoslavsky (The Hebrew University of Jerusalem, Israel) for X‐ray crystallographic analysis. A.N. gratefully acknowledges the Lady Davies fellowship trust for postdoctoral fellowship support. T.S. is grateful for a M.Sc. fellowship from The Hebrew University of Jerusalem, Israel. N.E. is thankful for a Ph.D. fellowship from the Neubauer Foundation.
© 2022 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.