Stereochemical prefixes

CIS (Section 3 11) Stereochemical prefix indicating that two substituents are on the same side of a nng or double bond (Contrast with the prefix trans )... 

Note that iD-myo-inositol 1-phosphate is the same as iL-myo-inositol 3-phosphate (and iL-myo-inositol 1-phosphate is the same as iD-myo-inositol 3-phosphate), but the lower locant has precedence over the stereochemical prefix (d or l) in naming the derivative. A consequence of applying the 1973 lUPAC-IUB rules to myo-inositol is that the numbering of C-2 and C-5 remains invariant. 

Z (stereochemical prefix), 173—175, 199 Z (symbol for atomic number), 7 Zaitsev, Alexander M., 184 Zaitsev s rule, 184, 191, 199, 200 Zidovudine, 1098 Ziegler, Karl, 246, 569 Ziegler-Natta catalyst, 246, 383, 567-570 Zigzag conformations of alkanes, 97 Zinc... 

Particular care is required in naming retinoids possessing additional substituents in the olefmic side chain. Comparison of the stereochemical designation of ethyl (all- )-retinoate (24) with the ester (29), which is substituted in the 10-position by fluorine, shows clearly that because of established rules (lUPAC, 1979) on the priority of substituents at double bonds, the stereochemical prefix has to be changed from E to Z, although the stereochemical configuration of the tetraene side chain has remained unchanged. 

The stereochemical prefixes E and Z should be used particularly where cis or trans may be ambiguous. For example, compound (29) may certainly be named as an all-trans compound on the basis of the steric arrangement of the polyene side chain. The E,Z nomenclature is of course less ambiguous in such cases. 

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