COC(=O)C1=C(C)N2[C@H](C(=O)O)CS[C@@]2(C)[C@H](C(=O)OC)[C@H]1c1cccc([N+](=O)[O-])c1
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?