title: Reversible Aromaticity Transfer in a Bora-Cycle: Boron-Ligand Cooperation.
abstract: Aromaticity is a central concept in chemistry. Reaction pathways involving reversible ligand dearomatization sequences emerged as a powerful tool for bond activation by metal complexes. Exploring this concept with a metal-free system, we have synthesized a pyridine-coordinated aminoborane which undergoes a temperature-induced formal dearomatization of the pyridine ring. NMR studies and DFT calculations revealed that this formal dearomatization sequence led to an aromaticity switch and the formation of a six-π-electron boron-containing heteroaromatic system. Disrupting this aromatic system by coordination of an amine or a carboxylic acid to the boron center enabled N-H activation and O-H cleavage, leading to an unprecedented reversal aromaticity switch.
authors.affiliation: Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Urs
authors.initials: U
authors.lastname: Gellrich
authors.affiliation: Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Yael
authors.initials: Y
authors.lastname: Diskin-Posner
authors.affiliation: Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: Linda J W
authors.initials: LJ
authors.lastname: Shimon
authors.affiliation: Department of Organic Chemistry and ‡Department of Chemical Research Support, Weizmann Institute of Science , Rehovot 76100, Israel.
authors.forename: David
authors.initials: D
authors.lastname: Milstein