CIP convention

In the Fischer convention, all common proteinogenic amino acids belong to the L series, but w ith the CIP convention the S configuration does not universally apply, (/ )-cysteine being an exception. 

The faces of the carbonyl carbon in, eg. 9. and of the sp2 hybrid carbons of alkenes, are assigned configurations Re or Si, based on the CIP convention as long as these carbons have three different substituents. 

Note that there is no 1-1-correspondence between orientation and the Cahn-ln-gold-Prelog (CIP) convention. The orientation of a particular quadruple depends on the numbering of atoms, not on their nature. Thus, exchanging atom numbers 3 and 4 in conformation 4.2a, as shown in 4.2a , will result in the orientation... 

In the course of retrosynthetic consideration of TM 1, we completely neglected the stereochemistry. This is chiral molecule, and in praxis usually preparation of one enantiomer, denoted as asymmetric synthesis or synthesis of an enantiomerically pure compound, is targeted. When more stereogenic centers are present, expression of the asymmetric synthesis of an optically pure compound is preferred. Let as now assume that our target is (5)-TM 1 (for R, S nomenclature and CIP convention, see Sect. 3.1). 

Cycloadducts 36 and 37 are produced as racemic mixtures. Thus the RS descriptors only indicate relative stereochemistry. Fmrthermore, I have assigned RS stereochemistry not according to the Cahn-Ingold-Prelog (CIP) convention, but to indicate the diastereomeric juvabione that would be produced from the indicated cycloadduct. 

In the areas of coordination and metalorganic compounds the CIP system was adopted in part (Sequence Rules), but a variety of special conventions mainly concerning constitution and descriptor assignment rules for stereogenic centers with more than four ligands have emerged. An excellent review is available1, and here only those types of compounds relevant to this volume are discussed. 

Nonracemic chiral ferrocenes became available in the 1960s, following the second paper from the CIP team. Schlogl8 and co-workers first used planar chirality to describe these compounds. In the third paper from the CIP team in 19669, -complexes were treated explicitly by a convention for n-complexes ... 

Applying the pseudo-atom convention to the iron complex in Figure 8, the iodine atom is priority 1, the t1S-C5H3R2 ligand is priority number 2, the phosphorus atom is priority number 3, and carbon is priority number 4.15 When the iron is viewed from the side opposite the priority number 4, the sequence is 1,2,3 in the anticlockwise or 5 direction. The highest priority carbon in the cyclopentadienyl ligand, indicated by an asterisk, is designated with the R chirality symbol by application of the extended CIP sequence rule. 

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