Oxidative Cycloaddition Reactions of Arylboron Reagents via a One-pot Formal Dehydroboration Sequence.

Arylboron compounds are widely available and synthetically useful reagents in which the boron group is typically substituted. Herein, we show that the boron group and -hydrogen atom are substituted in a formal cycloaddition reaction. This transformation is enabled by a one-pot sequence involving diaryliodonium and aryne intermediates.

Orbital analysis of bonding in diarylhalonium salts and relevance to periodic trends in structure and reactivity.

Diarylhalonium compounds provide new opportunities as reagents and catalysts in the field of organic synthesis. The three center, four electron (3c-4e) bond is a center piece of their reactivity, but structural variation among the diarylhaloniums, and in comparison with other λ-iodanes, indicates that the model needs refinement for broader applicability. We use a combination of Density Functional Theory (DFT), Natural Bond Orbital (NBO) Theory, and X-ray structure data to correlate bonding and structure for a λ-iodane and a series of diarylchloronium, bromonium, and iodonium salts, and their isoelectronic diarylchalcogen counterparts.

Refining boron-iodane exchange to access versatile arylation reagents.

Aryl(Mes)iodonium salts, which are multifaceted aryl transfer reagents, are synthesized boron-iodane exchange. Modification to both the nucleophilic (aryl boron) and electrophilic (mesityl-λ-iodane) reaction components results in improved yield and faster reaction time compared to previous conditions. Mechanistic studies reveal a pathway that is more like transmetallation than SAr.