[{"from": "human", "value": "From the provided chemical reaction, propose some possible reagents that could have been used. [C][N][C].[N][C][=Branch1][C][=O][C][C][C][C][Br]>>[C][N][Branch1][C][C][C][C][C][C][C][Branch1][C][N][=O]"}, {"from": "gpt", "value": "[C][C][O]"}]