CIP nomenclature

The R and S nomenclature was first presented in 1951 by Cahn and Ingold [26], and then consolidated and extended by Cahn, Ingold and Prelog [27,28]. The essential part of this nomenclature (also called the CIP nomenclature) of chiral centers is the sequence rule, i.e., a set of arbitrary but consistent rules which allow a hierarchical assignment of the substituents (a > b > c > d). 

Does CIP nomenclature adequately handle molecules with multiple stereoelements A case study of vancomycin and cognates 01AG(E)701. 

Defined in terms of the projection of the C-N bond on the pseudo-C3 axis of the complex in terms of Cahn, Ingold and Prelog (CIP) nomenclature all six stereogenic nitrogen atoms have S configuration. 

Nicolaou, K. C., Boddy, C. N. C., and Siegel, J. S. "Does CIP Nomenclature Adequately Handle Molecules with Multiple Stereoelements A Case Study of Vancomycin and Cognates." Angew. Chem. Int. Ed. Eng., 40,701 (2001). 

The CIP nomenclature has been applied to virtually all chiral molecules, such that chemists are able to communicate to each other the absolute structure of such species in an unambiguous... 

The result of this method is consistent with that obtained by using the corresponding Mosher s ester method (Adn = d(/o-ATMA - (s)-atma) (Fig- 1-25). Note that in the method of Mosher s ester, (Ss — Sr) was applied to calculate Ah) i, the difference in the 2ATMA method is only due to the configuration nomenclature difference caused by the CIP rule. 

The currently used (R,S)-nomenclature of asymmetric C-atoms and similar tetracoordinate configurations is based upon the sequential order of the ligands derived from the CIP rules. If one orients an asymmetric C-atom in such a manner that the fourth ligand points backwards, the indices of the first three ligands of an (I )-configuration increase in a clockwise pattern, and counterclockwise for an (S)-configuration. 

The (I ,S)-nomenclature still reminds the user of the right and left handed helical pattern arising from Fresnel s 29> interpretation of optical activity. These patterns are characterized by the combination of a translational and a rotational direction. The Ta skeletal symmetry of tetracoordinate systems submits itself to the pictorial models not applicable to other configurational types. The CIP rules may as well be used to define a configurational nomenclature on the basis of the Fischer projection. If one specified that in such a projection of an (R)-... 

In Figure 4.2 we have drawn how we can distinguish the two faces of an alkene, or rather the side of attack of a specific atom of the alkene. The arrow on the left approaches the lower carbon of the alkene and when looking from this viewpoint we count the weight of the three substituents the same way as in the CIP rules. We then see the order 1, 2, and 3 counter-clockwise, and we say that the arrow approaches the carbon atom from the si face. For simplicity we call this the si face of the alkene and in most cases this will do. If all four substituents at the alkene are different we can determine the re/si properties of both carbon atoms and these may be different This results in the nomenclature that an alkene may have a re,re and si,si face or re,si and si,re face. Thus, in the latter case one has to indicate to which atom the label is referring. For any enantiospecific, catalytic reaction (hydrogenation, hydroformylation, polymerisation) it is very convenient to use the re and si indicators in the discussion. 

It is our intention to present strategies based on chemically induced phase separation (CIPS), which allow one to prepare porous thermosets with controlled size and distribution in the low pm-range. According to lUPAC nomenclature, porous materials with pore sizes greater than 50 nm should be termed macroporous [1]. Based on this terminology, porous materials with pore diameters lower than 2 nm are called microporous. The nomination mesoporous is reserved for materials with intermediate pore sizes. In this introductory section, we will classify and explain the different approaches to prepare porous polymers and to check their feasibility to achieve macroporous thermosets. A summary of the technologically most important techniques to prepare polymeric foams can be found in [2,3]. 

FIGURE 5.5 Application of C/A nomenclature rules to [Co(CN)2(NH3)2(H20)2]+. The numbers are the CIP priority numbers, and the overall chirality is C. (See the color version of this hgure in Color Plates section.)... 

In this context, the E- and Z-nomenclature of ester enolates and silyl ketene acetals refers to their geometries where the carbonyl oxygen given highest priority irrespective of priority by CIP Cahn-Ingold-Prelog) rules. 

In the stereochemical nomenclature of coordination compounds, the procedure for assigning priority numbers to the ligating atoms of a mononuclear coordination system is based upon the standard sequence rules developed for chiral carbon compounds (the Cahn, Ingold, Prelog or CIP rules6, see Section IR-9.3.3.2). 

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