Multi-bond forming and iodo-selective base-promoted homolytic aromatic substitution

Base-promoted homolytic aromatic substitution (BHAS) has been applied as a means to effect multi-bond forming reactions. Using the dioxepine framework to illustrate the concept, BHAS was used to rapidly access regio-defined polycycles in merely 2 or 3 steps from iodophenol. Both liquid and solid arenes of an electronically-diverse nature were used as the coupling partner/solvent. DMSO additive was found to promote this multi-BHAS reaction. A pathway consistent with these observations is suggested, this hypothesis was exploited to further develop an iodo-selective BHAS reaction.