DFT investigation of coupling constant anomalies in substituted -lactams

beta-lactams are a chemically diverse group of molecules with a wide range of biological activities. Having recently observed curious trends in (2)J(HH) coupling values in studies on this structural class, we sought to obtain a more comprehensive understanding of these diagnostic NMR parameters, specifically interrogating (1)J(CH), (2)J(CH), and (2)J(HH), to differentiate 3- and 4-monosubstituted beta-lactams. Further investigation using computational chemistry methods was employed to explore the geometric and electronic origins for the observed and calculated differences between the two substitution patterns.