A Zinc-Bcat Compound: Unlocking New and Diverse Reactivity Pathways Beyond Nucleophilic Borylation

Abstract A zinc-boryl species was successfully synthesized from a common diboron reagent, B2cat2. In contrast to the known non-boron-ester-based zinc-boryl compounds with limited reactivity, this novel Zn-Bcat species exhibited a rich reactivity not only as a nucleophilic Bcat− anion, but also towards various nitrogen-containing unsaturated substrates, such as carbodiimides, isonitriles, and azobenzene, facilitating the Zn-B bond dissociation and the formation of Zn-C/N, B-N bonds, and cleavage of C = N double bond. The enhanced diverse reactivity of this species is likely attributed to the stronger covalency of the Zn-B bond. The structural information of the borylation products was fully characterized by NMR, HRMS spectra, and X-ray single-crystal analyses. Additionally, the Zn-Bcat compound was found to promote the catalytic diborylation of azobenzene, highlighting the versatility of the Zn-Bcat species as a reactive intermediate. Furthermore, DFT computational studies were carried out to shed light on the electronic structure and reactivity of the Zn-B bond.