Carbon-13, nitrogen-15 and oxygen-17 NMR chemical shifts of substituted 1-phenyl-2-pyrrolidinones

Abstract

The carbon-13 and nitrogen-15 NMR chemical shifts and the direct carbon—proton coupling constants of 1-phenyl-2-pyrrolidinone and its 2′-methyl, 3′-methyl, 4′-methyl, 2′-chloro, 3′-chloro, 4′-chloro, 3′-methoxy, 4′-methoxy and 4′-nitro derivatives were measured in dimethyl sulfoxide. The oxygen-17 NMR chemical shifts of some of the compounds were determined in acetone. The effect of substituents on the chemical shifts of carbonyl carbons correlates well with the Hammett substituent parameters and the nitrogen chemical shifts seem to follow a similar trend. The variation of the oxygen chemical shift due to the substituents is small. The chemical shifts of aromatic carbons can mainly be derived using the substituent parameters of benzene; some deviation probably due to steric effects is observable, however.