ON THE CONFORMATIONS OF LACTONE RINGS

The structures and relative energies of the various conformations have been determined for the simple lactones containing U-8 ring members by molecular mechanics (MM2) calculations. The h-, 5-, 6-, 7-, and 8-membered rings are found as conformational mixtures of 1, 1, 2, 1 and 4 conformations, respectively, neglecting conformations with energies more that 2 kcal/mol above the most stable conformation. There is good agreement with the (fragmentary) experimental information available. © 2013, Walter de Gruyter. All rights reserved.