Direct Conversion of Aromatic Lactones into Bioisosteres by Carbonyl‐to‐Boranol Exchange

Bioisosteric replacement is an important strategy in drug discovery and is commonly practiced in medicinal chemistry, however, the incorporation of bioisosteres typically requires laborious multistep de novo synthesis. The direct conversion of a functional group into its corresponding bioisostere is of particular significance in evaluating structure‐property relationships. Herein, we report a functional‐group‐exchange strategy that enables the direct conversion of aromatic lactones, a prevalent motif in bioactive molecules, into their corresponding cyclic hemiboronic acid bioisosteres. Scope evaluation and product derivatization experiments demonstrate the synthetic value and broad functional‐group compatibility of this strategy, while the application of this methodology to the rapid remodeling of chromenone cores in bioactive molecules highlights its utility.