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 C=CCn1nc(-c2cnc3c(n2)c(C(=O)NC(C)C(=O)N2CC(C#N)C2)cn3COCC[Si](C)(C)C)c2ccc(Cl)cc21 .
assistant