Conformational analysis of 3-deoxy-3-nitroheptoseptanosides by molecular mechanics (MM2) and theoretical 3JHH calculation

Molecular mechanics (MM2) calculations were performed on conformers of a series of stereoisomeric methyl 5,7-O-benzylidene-3-deoxy-3-nitro-α-d-heptoseptanosides. The lowest-energy conformations are twist forms derived from the regular 5C1,2 and OC3,4 chairs. The data obtained for the steric energies and the theoretically calculated 3JH,H coupling constants of the compounds are consistent with experimental observations on the synthetic products.