Aryl-Csp(3) bond rotation barriers of 2-aryl perhydropyrrolo[3,4-c]pyrrole-1,3-diones.
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.
Damodaran
Krishnan
K
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Nielsen
Simon D
SD
Geib
Steven J
SJ
Zhang
Wei
W
Lu
Yimin
Y
Curran
Dennis P
DP
D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D011758:Pyrroles / Q000737:chemistry*; D012399:Rotation; D013237:Stereoisomerism; D013816:Thermodynamics
D011758:Pyrroles; C545162:perhydropyrrolo(3,4-c)pyrrole-1,3-dione