Stereochemical designator

R,S stereochemical designations (Section 9.5) can be assigned to the chirality center in a Fischer projection by following three steps, as shown in Worked Example 25.1. 

The stereochemical designations employed for organometallic complexes follow an extension of the CIP system2. In all cases, the chiral metal atom has a higher atomic number and thus receives priority. The main feature of this extension of the CIP system concerns treatment of polyhapto ligands such as cyclopentadienyl ... 

Problem 6.62 Give the configuration, stereochemical designation and R,S specification for the indicated telrahydroxy products. 

Problem 9.4 Give the names, structural formulas and stereochemical designations of the isomers of (u) bromochlorocyclobutane, (ft) dichlorocyclobutane, (c) bromochlorocyclopentane, (d) diiodocyclopentane, (e) dimethylcyclohexane. Indicate chiral C s. ... 

Problem 9.38 Draw the structural formulas and give the stereochemical designation meso, rac, cis, trans, achiral) of all the isomers of trichlorcyclobutane. <... 

Problem 13.52 Supply structural formulas and stereochemical designations for the organic compounds (A) through (H). 

Problem 13.62 Write structural formulas with stereochemical designations for the reaction products 1 and II. 

Give the structure and stereochemical designation of all possible poly(a-olefin)s that could, in principle, be obtained by stereospecific polymerisation. Are they all likely to be obtainable in practice (with heterogeneous and homogeneous Ziegler-Natta catalysts) ... 

Give the structure and stereochemical designation of all possible cycloolefin polymers that might, in principle, be obtained by stereospecific ring-retaining polymerisation. 

Baer, E. and Buchnea, D. (1959) Synthesis of L-a-(dioleoyl)-cephalin, with a comment on the stereochemical designation of glycerol phosphatides,./. Am. Chem. 

Fig. 23. Definitions of the A and A stereochemical designations for diastereomeric metal-nucleotide complexes.

These sugars too have given their names to a stereochemical designation— erythro- and threo- are used to describe diastereoisomers that resemble these two sugars. We do not use these ratherambiguous terms in this book, preferring more precise or vivid terms such as R,Ror ant/as appropriate. 

The stereochemical designation of a tetrahedral chiral centre is determined by the priorities of the four substituents. The convention applies to all tetrahedral centres, not just carbon. Priorities in the first instance are determined by atomic weight (not atomic number the convention works for molecules chiral by isotopic substitution). The chiral centre is viewed along the line of the bond from the central atom to the substituent of lowest priority, with the central atom in front. If the priorities of the three remaining substituents decrease clockwise the stereochemistry is R (for rectus, right in Latin), otherwise it is S (for sinister, left). 

---