Gottfried Lubkowitz

Tri­phenyl­boroxin complex with N-cyclo­hexyl­hydroxy­lamine and its isobutyr­aldehyde nitro­ne

# 2002 International Union of Crystallography Printed in Great Britain ± all rights reserved N-Cyclohexylhydroxylamine(O±B)triphenylboroxin N-cyclohexyl-C-(2-propyl)nitrone hemibenzene hemisolvate, C24H28B3NO4.C10H19NO 0.5C6H6, contains one molecule of Ncyclohexylhydroxylamine in its N-oxide form added to a boroxin heterocycle, with one molecule of N-cyclohexyl-C-(2propyl)nitrone linked by an O HÐN hydrogen bond to the protonated hydroxylamine moiety, and a molecule of benzene which is located on a centre of inversion.

Structural Characterization of “Frozen” Intermediates in the Transition from an Eight-Membered Monocyclic System to a Bridged Ring Bicyclo[3.3.O]Octane

Abstract The strength of the transannular N→B interaction in the substituted cycloboronate 1,3,5-trioxa-6,8-diaza-2,4-diboracyclooctane 1 can be controlled both by varying the Lewis basicity of the ring nitrogen atoms and by modifying the steric factors dependent on the nature of the nitrogen substituents (by changing R). Examples of the structural types displaying varying degrees of transannular bonding have been prepared and characterized by X-ray analysis. A simple six-membered cycloboronate structure 4 containing one boron atom is formed when the basicity of the aminal nitrogen atom is reduced and the boronic acid residue is sterically hindered [R = C(CH3)2CN and Ar = 2,4,6-(CH3)3C6H2]. The bicyclo[3.3.0]octane structure 3 is obtained when R = simple alkyl and Ar = phenyl. A structural type between 1 and 2 is realized when R = C(CH3)2CN and Ar = Ph.