COC(=O)C1OC(=O)C2O[C@]23[C@@]1(C)CCC1[C@@]3(C)C(OC(C)=O)CC2C(C)(C)C(=O)CC[C@@]21C
Molecules with a polar surface area of greater than 140 angstroms squared (Å2) tend to be poor at permeating cell membranes. What's the psa of this molecule?