You are a chemist. Now you are given a product molecule. Please predict the the reactant molecules of the reaction.
The reaction equation has the following format:
```
reactant1.reactant2. ... .reactantN>>product
```
Your task is to predict the structure representation of the reactant molecule. We provide the SMILES of the reactants.
system
<molecule_2d> Given the product provided, propose some possible reactants that could have been employed in its formation.
user
Here are possible reactants: CO.O=C(O)c1ccc(Br)cc1F .
assistant