13C NMR discrimination of regioisomeric bispyrroloquinone/ bispyrroloiminoquinone ring systems

Article abstract of DOI:10.1002/mrc.2529

The structural assignment of bispyrroloquinone and bispyrroloiminoquinone regioisomers was achieved using ¹³C NMR spectral data. In the case of bispyrroloiminoquinones, the carbonyl group in the regioisomer possessing a nitrogen atom in both α-positions was systematically less deshielded than the carbonyl group in the other regioisomer. In the case of bispyrroloquinones, the most deshielded carbonyl group in the regioisomerwith a nitrogen atom in both α-positions wasmore deshielded than the same carbonyl group in the other regioisomer. Copyright