title: Axial-selective H/D exchange of glycine-derived 1H-benzo[e][1,4]diazepin-2(3H)-ones: kinetic and computational studies of enantiomerization.
abstract: Glycine-derived 1H-benzo[e][1,4]diazepin-2(3H)-ones (BZDs) 5d-g featuring C9- and N1- substitution exhibit enantiomerization barriers too high to be measured by (1)H NMR coalescence experiments. To address this problem, we found that room-temperature H/D exchange of these compounds is remarkably selective, affording only the axial-d(1) isotopomers. (1)H NMR spectroscopy was then employed to measure the rate of conformational inversion of these d(1)-compounds at elevated temperatures. These studies reveal the highest enantiomerization barriers (up to 28 kcal/mol) ever determined for a BZD. Density functional theory calculations match the experimental enantiomerization barriers within 1.2 kcal/mol.
authors.affiliation: Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, USA. pcarlier@vt.edu
authors.forename: Paul R
authors.initials: PR
authors.lastname: Carlier
authors.forename: Yang-Sheng
authors.initials: YS
authors.lastname: Sun
authors.forename: Danny C
authors.initials: DC
authors.lastname: Hsu
authors.forename: Qiao-Hong
authors.initials: QH
authors.lastname: Chen
mesh_terms: D001381:Azepines / Q000737:chemistry*; D005998:Glycine / Q000737:chemistry*; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: C554654:1H-benzo(e)(1,4)diazepin-2(3H)-one; D001381:Azepines; D005998:Glycine