Boronnitrogen compounds : LXI. Studies on (2-pyridylamino)diphenylborane and some related species

Abstract

(2-Aminopyridine)-triphenylborane, (2-H 2NC 5H 4N)B(C 6H 5) 3, has been prepared from its acidbase pair constituents; pyrolysis of the compound yields B-triphenyl- N-tris(2-pyridyl)borazine, [BC 6H 5N(2-C 5H 4N)] 3. An intermediate in the transamination of (dimethylamino)diphenylborane with 2-aminopyridine to yield (2-pyridylamino)diphenylborane, (2-C 5H 4N)NHB(C 6H 5) 2, has been isolated and was identified to be a 1 : 1 molar adduct of (dimethylamino)diphenylborane with 2-aminopyridine. Somewhat related to this 1 : 1 adduct is a material that is obtained as initial product of the interaction of (2-pyridylamino)diphenylborane with water, which can be formulated as a 1 : 1 : 1 adduct of (2-pyridylamino)diphenylborane, (hydroxy)diphenylborane and 2-aminopyridine; pyrolysis of this species yields (diphenylboryl)(2-pyridylamino-phenylboryl) oxide, (C 6H 5) 2BOBC 6H 5NH(2-C 5H 4N), for which a coordinated cyclic structure is suggested. This same diboryl oxide is obtained from the interaction of (2-pyridylamino)dipheynylborane with molecular oxygen and also by the reaction of the cited aminoborane with acetophenone via oxygen abstraction from the latter. (2-Pyridylamino)diphenylborane 1,2-aminoboronates one CO double bond of carbon dioxide; this reaction is analogous to the reaction of (2-pyridylamino)diphenylborane with aldehydes or ketones as described previously.