COc1ccc(-c2cc(=O)oc3c(C)c(OCC(=O)NC[C@H]4CC[C@H](C(=O)O)CC4)ccc23)cc1
An acid's negative base-10 logarithmic dissociation constant (pka) follows directly from its underlying thermodynamics; pKa is directly proportional to its standard Gibbs free energy change. What is the pka value of this molecule?