You are a chemist. Now you are given a description of a molecule. Please generate a molecule that meets the description.
system
Generate a molecule that fulfills the requirement: The molecule is a proteasome inhibitor.
user
O=C1CN(N=CC(Cc2ccccc2)NC(=O)C(Cc2c[nH]c3ccccc23)NC(=O)C(Cc2c[nH]c3ccccc23)NC(=O)OCc2ccccc2)C(=O)N1
assistant