Synthesis of Norbornanes via Photosensitized Strain-Release Cycloaddition of Housane

Abstract

Norbornanes are important scaffolds in organic chemistry that have been used as synthetic intermediates and as core scaffolds in drugs. These are commonly prepared by Diels–Alder cycloaddition of cyclopentadiene and an alkene. While useful, the synthesis of bridgehead substitutions can be challenging. In this work, a photochemical strain-release cycloaddition of a housane and alkenes is disclosed to prepare bridgehead-substituted norbornanes. The reaction proceeds through energy-transfer activation of naphthyl-substituted housane and enables direct access to substitution patterns that are difficult to obtain through conventional approaches. A broad range of alkenes and alkynes is tolerated under the mild reaction conditions, providing a modular entry into structurally diverse norbornanes.