Using COC(=O)C1CC(=O)CN1C(=O)OC(C)(C)C, C=CC[Sn](CC=C)(CC=C)CC=C to produce C=CCC1(O)CC(C(=O)OC)N(C(=O)OC(C)(C)C)C1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.