Hydrogen bonding vs steric gearing in a hexasubstituted benzene.
Treatment of hexakis(bromomethyl)benzene with excess NaN 3, followed by hydrogenation of the resultant polyazide, affords hexamine 3 in high yield. Coupling to six equivalents of nonanoic acid provides hexamide 5 without chromatographic purification. The NH resonance of 5 appears far downfield (approximately 9.7 ppm) in CDCl3 and is unaffected by changes in concentration or by addition of chloride or trifluoromethanesulfonate ions. DFT calculations predict that 5 exists as a bowl, with all six substituents intramolecularly H-bonded together on one side of the plane defined by the anchoring arene.
Gavette
Jesse V
JV
Department of Chemistry, Science and Technology Building, East Carolina University, Greenville, North Carolina 27858-4353, USA.
Sargent
Andrew L
AL
Allen
William E
WE