[{"from": "human", "value": "Given this chemical reaction, what are some reagents that could have been used? [Br][Br].[C][C][=Branch1][C][=O][C][C][C][N+1][=Branch1][C][=O][O-1]>>[O][=C][Branch1][Ring1][C][Br][C][C][C][N+1][=Branch1][C][=O][O-1]"}, {"from": "gpt", "value": "[C][O].[O]"}]