Non-chair six-membered-ring conformations. Preference for a twist-boat (or skew) structure in α-L-sorbopyranose derivatives
作者:Michael J. Costanzo、Harold R. Almond、A.Diane Gauthier、Bruce E. Maryanoff
DOI:10.1016/s0957-4166(00)80393-6
日期:1994.12
The conformational preferences for 2,3-O-isopropylidene-alpha-L-sorbopyranose derivatives 3-6 were determined by using H-1 NMR data and empirical force field calculations. Proton NMR studies of 3-6 indicate that a twist-boat (or skew) conformation (S-3(0)) prevails over possible chair forms for each compound. Force-field calculations (MM2, MNDO, AM1) on a model 2,3-O-isopropylidene-alpha-L-sorbopyranose system (18) indicate that the S-3(0) conform ation is among the low-energy structures. X-Ray crystallographic analysis of alpha-L-sorbopyranose sulfamate 3, a compound with potent anticonvulsant activity, demonstrates that the S-3(0) skew conformation is manifested in the solid state, as well.