(16) DH Wertz and NL Allinger, Tetrahedron, 30, 1579 (1974).(17) NL Allinger and JT Sprague, J. Am. Chem. SOC., b5, 3893 (1973).(18) The computation of the energy of a given conformation of the acetate 3c takes about 3 min with the IBM 370/166 computef. Thirty seven points (every lo") were calculated.
