Molecular mechanic (MM2) calculations were performed on conformers of a series of stereoisomeric methyl 5,7-O-benzylidene-3-deoxy-3-nitro-a-D-heptoseptanosides. The lowest-energy conformations are twist form derived from the regular ⁵C_1,2 and ⁰C_3,4 chairs. The data obtained for the steric energies and the theoretically calculated ³J_HH coupling constants of the compounds are considered with experimental observations on the synthetic products.