Boron-Catalyzed O–H Bond Insertion of α‑Aryl α‑Diazoesters in Water

A catalytic, metal-free O–H bond insertion of α-diazoesters in water in the presence of B­(C₆F₅)₃·nH₂O (2 mol %) was developed, affording a series of α-hydroxyesters in good to excellent yields. The reaction features easy operation and wide substrate scope, and importantly, no metal is needed as compared with the conventional methods. Significantly, this approach further expands the applications of B­(C₆F₅)₃ under water-tolerant conditions.