The direction of addition of unsymmetrical reagents to ethyl y, y, y-trifluorocrotonate was of interest in order to determine whether the trifluoromethyl group or the carbethoxy group would be the controlling factor. In the former case, the trifluoromethyl group might be expected to direct the entering anion to the a-carbon atom through an inductive or hyperconjugative effect1 as illustrated in I. If the carbethoxy group were more important, ...
