The Fischer Projection
Correlation of the R,S Nomenclature and the Fischer Projection
The naming of absolute configuration with (R),(S) descriptors can be taken from the Fischer projection. For this purpose, the structure is illustrated in such a manner in the Fischer projection so that the substituent with the lowest CIP priority is located at the top. If the remaining three substituents are arranged clockwise in order of decreasing CIP priority, the absolute configuration is (R). If they are arranged counterclockwise however, the absolute configuration is (S).