In this case one now anticipates, and finds, an isotope discrimination. Again, using the formalism of the perepoxide for purposes of discussion, one sees that, in 7, the system has a choice of abstracting D from the chiral center or reacting with methyl CH bonds and, in 8, a choice of-H or the methyl CH. We find an isotope effect of 1.2. This is exactly half the effect (1.4) found for the system 9, which is ideally suited for 1 a 2 cis competition on both top ...
