Using COC(=O)CCC(=O)Nc1cnc(Br)cn1, C=C[Sn](CCCC)(CCCC)CCCC to produce C=Cc1cnc(NC(=O)CCC(=O)OC)cn1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.