Synthesis of gem-Di(boryl)cyclopropanes from Non-Activated Olefins via Mn-Photocatalyzed Atom Transfer Radical Addition

Abstract

The application of gem-diboryl cyclopropanes as versatile building blocks for enhancing molecular complexity has been limited, despite the availability of a few synthetic methods. Herein, we disclose a practical and versatile manganese-catalyzed protocol that enables the synthesis of gem-di(boryl)cyclopropanes from non-activated alkenes in combination with (diborylmethyl)iodides. This photoinduced strategy displays good functional-group tolerance, and encompasses a wide range of applicable substrates, making it applicable to the late-stage modification of natural products. Mechanistic experiments suggest that the reaction proceeds via an intermolecular halogen-atom transfer radical addition, followed by deprotonative alkylation with lithium diisopropylamide, ultimately yielding cyclization products. The versatility and practicality of this approach are further highlighted by the successful implementation of several transformations, which provide an expedited route for synthesizing highly functionalized molecules.