Winga, do you have an example of where you would have to pick between an R and an S sidechain? I'm trying to think of an example where the compound wouldn't be meso
because of a plane of symmetry.
Could someone describe about M/P configuration?
M is like R, P is like S. For axial chirality you also sometimes see aR and aS instead of just R and S.
With respect to Blueshawk's question, Winga is correct. The substituents on the "front" ring are automatically given higher priority than those on the "back" ring. So, the isopropyl groups are priority 1 and 3, respectively. The H atoms on the other side of the rings are 2 and 4, respectively.