O=C(N[C@@H]1C/C=C\C[C@H](CC(=O)N(CCO)Cc2ccccc2)C(=O)N[C@@H](Cc2c[nH]c3ccccc23)COC1=O)OCC1c2ccccc2-c2ccccc21
A higher negative pKa value denotes a less powerful acid. What is this molecule's negative pKa value?