DFT investigation of coupling constant anomalies in substituted β-lactams.

β-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 β-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.