Visible Light‐Driven Wolff Rearrangement/Formal (3+2) Cyclization of α‐Diazoketones with Bicyclo1.1.0butanes: Efficient and Highly Regioselective Access Oxabicyclo‐2.1.1hexane Scaffolds

The development of oxygen‐containing three‐dimensional bicyclic scaffolds as bioisosteres of aromatic rings is of increasing importance for improving physicochemical and pharmacokinetic profiles in modern pharmaceutical development. Herein, we report a catalyst‐ and additive‐free strategy to access a series of multifunctional oxa‐bicyclo2.1.1hexane derivatives in a single operation from readily accessible α‐diazoketones and bicyclo1.1.0butanes. The process involves a visible‐light‐mediated sequential Wolff rearrangement/2 π + 2 σ cycloaddition. Generally, this reaction proceeds under mild conditions and features broad substrate scope, good functional group tolerance, and high regiospecificity. The synthetic utility of this method is demonstrated through diverse synthetic transformations of the resulting products. Furthermore, control experiments and mechanistic studies were conducted, and a plausible mechanism is proposed to rationalize the observed efficiency.