CIP Rules and R/S Assignment Without Mistakes
Organic Chemistry · Stereochemistry CIP Rules and R/S Assignment Without Mistakes Almost every stereochemistry error at entrance level comes from three specific places. Fix those and the assignments become mechanical. BSc & MSc · Organic Chemistry · Method The short answer: Rank the four groups on a stereocentre by atomic number at the first point of difference, put the lowest priority away from you, and read 1→2→3. Clockwise is R, anticlockwise is S. The rules are short; the errors come from exploring branches in the wrong order and from mishandling the case where the lowest group points toward the viewer….