EXPERIMENTAL AND THEORETICAL-STUDY OF THE STRUCTURES AND OPTICAL ROTATIONS OF CHIRAL BICYCLIC ORTHO ESTERS

The approach adopted in this study was to determine the structure of a single crystal of a pure enantiomer of one of the ortho esters by X-ray diffraction and then to utilize the coordinates so found for the bicyclic moiety in calculating the optical rotations of the remaining members of the series. Because of the high sensitivity of the calculated rotations to the atomic coordinates, this approach is subject to the experimental uncertainties inherent in the X-ray diffraction technique. Thus, we explore here some restrained refinement procedures to reduce the effect of these uncertainties on the calculated molar rotations. Study shows that the dipole interaction theory accomplishes this for the esters though it also reveals a potential hazard in establishing this connection for molecules wherein interactions of high order among atoms are significant.