Cahn-Ingold-Prelog convention

Absolute Stereochemistry Absolute stereochemical assignment of each stereocenter (R vs S) Cahn-Ingold-Prelog Convention (sequence rules)... 

Figure 1.1 Schematic diagram explaining the Cahn-Ingold-Prelog convention for determining the absolute stereochemistry of a chiral molecule.

D-Glyceraldehyde in Fischer s convention (f )-glyceraldehyde in the Cahn-Ingold-Prelog convention... 

Scheme 2.1 Kinetic resolution of glycidyl butyrate catalyzed by porcine pancreatic lipase, PPL The preferential conversion of (S)-glycidyl butyrate into (R)-glycidol and butyric acid results from the stereochemical nomenclature rules under the Cahn, Ingold, Prelog convention, the configuration around the chiral centre is not affected.

To deal with this problem, we use the E-Z system of nomenclature (pun intended) for cis-trans isomers, which is patterned after the Cahn-Ingold-Prelog convention for asymmetric carbon atoms (Section 5-3). It assigns a unique configuration of either E or Z to any double bond capable of geometric isomerism. 

Most naturally occurring amino acids have chirality centers (the asymmetric a carbon atoms) that are named (S) by the Cahn-Ingold-Prelog convention (Section 5-3). The common naturally occurring form of cysteine has a chirality center that is named (R), however. 

C 20) configurations are designated 20a- or 20jS according to Fieser and Fieser Steroids, p. 337). Equivalent terms in the modern Cahn-Ingold-Prelog convention ( sequence rules") are -... 

The structure of the amino acid serine is shown in Figure 4.18. Draw a Fischer projection of the naturally occurring l isomer and determine the configuration using the Cahn-Ingold-Prelog convention. 

A Fischer projection of serine is shown in Figure 4.19. The carbon chain is drawn vertical with the most oxidised carbon at the top. For the amino acid to be a member of the L-series, the NH group must be on the left of the Fischer projection. The priorities for the Cahn-Ingold-Prelog convention are also shown in Figure 4.19. 

Figure 4.19 Fischer projection and Cahn-Ingold-Prelog convention for serine.

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