Absolute configuration sequence rules

With the lowest ranked group (hydrogen) directed away from us we see that the order of decreasing sequence rule precedence is clockwise The absolute configuration is R... 

R,S convention (Section 9.5) A method for defining the absolute configuration at chirality centers using the Cahn-IngoId-Prelog sequence rules. 

For compounds 7.42, the preferred substrate always had the 3D geometry shown here, which corresponded to an (R)- or -absolute configuration, depending on priorities assigned by the sequence rule, e.g., the (S,S)-enan-tiomer for X = CH2. The situation is not so clear-cut with compounds 7.43, with which contradictory results were obtained. 

Cahn, R. S. An introduction to the sequence rule. A system for the specification of absolute configuration. J. chem. Education 41, 116... 

The sequence rule (also known as the Cahn-lngold-Prelog (CIP) system) is the universal system of describing absolute configurations. It provides a method of arranging atoms or groups in an order of precedence and is used to assign stereochemical descriptors, R-, S-, also E-, Z-, and others. 

Diastereomer I and II liberated free ligands of (i ) - and (5)-configurations, respectively, on treating with sodium cyanide in water. The notation of absolute configuration of the ligand is reversed upon coordination by the sequence rule (6 ). ... 

CIP (Cahn, Ingold, Prelog) method, CIP system The CIP sequencing rules establish the conventional ordering of ligands for the unambiguous description of absolute configuration by descriptors such as R, S P, M E, Z. 

---