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Post‐Assembly Reactivity of N ‐Aryl Iminoboronates: Reversible Radical Coupling and Unusual B−N Dynamic Covalent Chemistry
Author(s) -
Keyzer Evan N.,
Sava Alexandru,
Ronson Tanya K.,
Nitschke Jonathan R.,
McConnell Anna J.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802790
Subject(s) - chemistry , covalent bond , diastereomer , bicyclic molecule , reactivity (psychology) , ring (chemistry) , aryl , stereochemistry , enantiomer , crystallography , organic chemistry , medicine , alkyl , alternative medicine , pathology
Post‐assembly reaction of a dynamic covalent iminoboronate system following addition of Cp 2 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 rac 5 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 ( rac 5 ) and fused bicyclic systems ( rac 6 ) 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 Ph 3 C + .