In Figure , we have a different story. Sorting by R gives A > B. But sorting by S also gives A > Bno switch! A naïve application of Rule 5, only checking the two R-reference like/unlike lists, would have assigned r to that center. However, this center is asymmetric, not pseudoasymmetric, because each ligand is its own enantiomorph. The ultimate descriptor will be R, not r. The analysis is the opposite for alkenes and even-atom cumulenes (Figure and). Thus, if the pair on only one end of the alkene reverses priority when using the S reference vs. using the R reference (Figure ), then the result is the asymmetric seqCis or seqTrans; if neither or both pairs reverse priority (Figure ), then the result is the pseudoasymmetric seqcis or seqtrans.