Using COC(=O)c1cc(Br)c2oc(N3CCOCC3)cc(=O)c2c1, C=C(OCC)[Sn](CCCC)(CCCC)CCCC to produce COC(=O)c1cc(C(C)=O)c2oc(N3CCOCC3)cc(=O)c2c1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.