A conformational study of a biologically active conjugated syn ‐oxime

The conjugated system (E)‐tiglaldoxime is the simplest example of a perillartine analog which exhibits sweetness with a taste potency greater than sucrose with almost no bitter aftertaste. In previous studies, the structure of this biologically active compound has been assumed to be planar with the CC double bond trans to the CN bond of the oxime moiety. In this article a conformational analysis of this molecule is reported. The results indicate that, although the trans conformer of the planar molecule is indeed the global minimum, other conformers lie within a few kilocalories of this minimum. Hence, other accessible conformations may be available for interaction with the receptor and, therefore, may be biologically active. The structural parameters obtained for this conjugated syn ‐oxime are nearly identical to those of (E)‐acetaldoxime. This fact has implications for the transferability of these parameters to the more complicated perillartine analogs.