You are a chemist. Now you are given a description of a molecule. Please generate a molecule that meets the description.
system
Come up with a molecule based on the description: The molecule is a proteasome inhibitor.
user
O=C(NC(CC1CC1)S(=O)O)C(Cc1ccccc1)NS(=O)(=O)c1ccc(N2CCOCC2)nc1
assistant