Using C[Si](C)(C)CCOCn1ccc2c(-c3cncs3)ncnc21, BrC(Br)(Br)Br to produce C[Si](C)(C)CCOCn1ccc2c(-c3cnc(Br)s3)ncnc21, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.