Photoinduced decarboxylative borylation of carboxylic acids

The conversion of widely available carboxylic acids into versatile boronic esters would be highly enabling for synthesis. We found that this transformation can be effected by illuminating the N-hydroxyphthalimide ester derivative of the carboxylic acid under visible light at room temperature in the presence of the diboron reagent bis(catecholato)diboron. A simple workup allows isolation of the pinacol boronic ester. Experimental evidence suggests that boryl radical intermediates are involved in