Using COP(=O)(CP(=O)(OC)OC)OC, CC(C)(C)OC(=O)CBr to produce COP(=O)(OC)C(CC(=O)OC(C)(C)C)P(=O)(OC)OC, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.