Synthesis of Functionalized 2‐Pyrrolidinones Bearing N‐Trifluoromethylphenyl through A Formal [4+1] Cycloaddition of Cinnamaldehyde Nitrones and 1‐Ethynylnaphthalen‐2‐ols

A variety of functionalized 2-pyrrolidinones bearing N-trifluoromethylphenyl moieties were prepared in moderate to good yields with high diastereoselectivity through copper(II)-catalyst and base co-catalyzed formal [4+1] cycloaddition of cinnamaldehyde nitrones with 1-ethynylnaphthalen-2-ols in the presence of m-CPBA as the oxidant. The triple bond of 1-ethynylnaphthalen-2-ol served as one-carbon synthon for the pyrrolidinone ring formation. Mechanistic studies revealed that m-CPBA played an important role to interrupt the intramolecular O-cyclization to afford the 2-pyrrolidinones. Moreover, the reaction could be easily performed at gram scales and the obtained products were selectively converted into diverse pyrroline scaffolds.