R,= H to reaction of the anion with the ester group1lb as well as the enol ether. This is not surprising: as the enol ether of a@-diketone is the vinylogue of an ester, the reactivities of the two systems should be comparable. We decided to differentiate between the two groups by forming the isobutyl enol ether ester 6c; as the addition of 2 to the carbonyl of the vinylogous ester is 1, 2, it should not be as subject to steric hindrance by the isobutyl ...
