Synthesis and characterisation of new substituted o-quinodimethane dimers via Diels–Alder reaction: formation of spiro compounds

Spirocyclic motifs are present in natural products and play an important role in drug discovery. The synthesis of spirocyclic compounds, however, often presents significant challenges. We present a simple and efficient strategy towards the construction of spiro[cyclohexane-1,2'-naphthalene]-2,4-diene scaffolds. The base-mediated dimerisation of substituted 1,2-bis(bromomethyl)benzene derivatives led to spiro compounds in a Diels–Alder reaction via o-quinodimethane intermediates. Two target compounds were obtained and fully structurally characterized by NMR spectroscopy and single crystal X-ray diffraction analysis.