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.