Direct Synthesis of Highly Substituted Cyclopentadienes and Derivatives from the Self‐Condensation of Renewable Ethyl Levulinate

Tri‐substituted cyclopentadienes and cyclopentanes, high‐value‐added compounds, are readily prepared from ethyl levulinate, a chemical platform easily obtained from biomass. Key steps involve coupling two molecules of ethyl levulinate in the presence of pyrrolidine, followed by a base‐catalyzed intramolecular aldol condensation, to provide a singly‐purified and easily derivatizable cyclopentadiene in almost 40 % isolated overall yield. Reaction conditions are mild, simple and employ green solvents such as ethanol and anisole. This method opens a new pathway to preparing complex molecules from renewable feedstocks.