Post-Assembly Reactivity of N-Aryl Iminoboronates: Reversible Radical Coupling and Unusual B-N Dynamic Covalent Chemistry.

ABSTRACT: Post-assembly reaction of a dynamic covalent iminoboronate system following addition of Cp₂ Co resulted in the formation of a series of new reductively coupled dianionic dimers via C-C bond formation. The dimers formed as a mixture of BN-containing isomeric products: diastereomers rac₅ and meso_5, with coupled five-membered rings, and enantiomeric rac_6, with a fused six-membered ring bicyclic system from C-C bond formation and rearrangement of the B-N bonds. Each isomer was identified using ¹ H?NMR spectroscopy in combination with single crystal X-ray structure determination. Interestingly, interconversion between the coupled five-membered rings (rac₅ ) and fused bicyclic systems (rac₆ ) was found to occur through an unprecedented breaking and reforming of the B-N covalent bond. Further, the coupled products could be converted quantitatively back to their iminoboronate precursors with addition of the electron abstractor Ph₃ C⁺ .

SUBMITTER: Keyzer EN 

PROVIDER: S-EPMC6175077 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature