Using COC(=O)c1cn(COCC[Si](C)(C)C)c(Br)n1, C=C(OCC)[Sn](CCCC)(CCCC)CCCC to produce C=C(OCC)c1nc(C(=O)OC)cn1COCC[Si](C)(C)C, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.