O(CC)C(=O)C1=C(NC(=C1C)C2=C(C)C(C(=O)OCC)=C(N2)C3=C(C(=O)OCC)C(C)=C(N3)C(=O)OCC)C4=C(C(=O)OCC)C(C)=C(N4)C(=O)OCC