title: Aryl-Csp(3) bond rotation barriers of 2-aryl perhydropyrrolo[3,4-c]pyrrole-1,3-diones.
abstract: The static and dynamic features of 2-aryl perhydropyrrolo[3,4-c]pyrrole-1,3-diones bearing N-acyl substituents have been assessed with the aid of crystal structures and VT NMR spectra. Rotation barriers for the aryl-Csp(3) bonds in these molecules show surprising variation. Amide-substituted derivatives and fused piperazinediones (six-membered fusion) exhibit very substantial barriers of 14-15 kcal/mol. Fused benzodiazepinediones (seven-membered fusion) have lower but still significant barriers (10 kcal/mol), while fused hydantoins (five-membered fusion) have barriers that are too low to measure by VT NMR (< or =10 kcal/mol). A rationale for the origin of the barriers is presented.
authors: Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors: Krishnan
authors: K
authors: Damodaran
authors: Simon D
authors: SD
authors: Nielsen
authors: Steven J
authors: SJ
authors: Geib
authors: Wei
authors: W
authors: Zhang
authors: Yimin
authors: Y
authors: Lu
authors: Dennis P
authors: DP
authors: Curran
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D011758:Pyrroles / Q000737:chemistry*; D012399:Rotation; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D011758:Pyrroles; C545162:perhydropyrrolo(3,4-c)pyrrole-1,3-dione