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
Do retrosynthesis with the product <molecule_2d> .
user
OK. The reactants may be CC(C)(C)C(=O)OCCn1nc(OC2OC(COC(=O)C(C)(C)C)C(OC(=O)C(C)(C)C)C(OC(=O)C(C)(C)C)C2OC(=O)C(C)(C)C)c2c(CCc3ccc(CCCC(=O)NC(C)(C)C(=O)O)cc3)cccc21.OCCN1CCNCC1 .
assistant