SEMIEMPIRICAL CALCULATIONS FOR THE DETERM INATION OF THE CONFORMATIONOF 4,5-DIHYDRO-1,3-DIOXEPINE AND ITS 2-METHYL DERIVATIVE

The possible conformations of the title compounds have been studied wi th the semiempirical methods MNDO and AM1. In the local minima, the vi bration frequencies have been calculated to get the free enthalpy of e ach conformer and its equilibrium concentration. The energy minimized structures and the calculated thermodynamical values are compared with experimental results. From our investigations we conclude that the ch air conformation is preferred. In the case of the methyl derivative, t he substituent favours the equatorial position.