My question is about problem 45a in chapter 6 of John McMurry'sOrganic Chemistry, 7th ed. In this problem, we are asked todetermine whether a substituted alkene should be designated "Z" or"E". The carbon on the right side of the double bond isconnected to a CO2H group on the top and a hydrogen atomon the bottom. However, the carbon on the left side of thedouble bond is part of a cyclohexane ring. There is a methylgroup attached to the ring, 2 carbons away from the double-bondedcarbon. The methyl group is on the same side of the doublebond as the CO2H group of the other double-bonded carbon("top").
My question is as follows. How do you assignCahn-Ingold-Prelog priorities to the substituents of a particularcarbon atom when the carbon atom in question is part of a ring? There aren't 2 different substituents! Where does the"top" substituent end and where does the "bottom" substituentend?