Conformational studies by nuclear magnetic resonance—V: 13C spectra and structural problems of enamino carbonyl compounds

A ¹³C magnetic resonance investigation of 22 compounds of the general formula O?C¹(R¹)C²(R²)?C³(R³) NR⁴R^4′ has been carried out in order to confirm the conformational assignments estimated previously by PMR and IR spectroscopy. The effects of nonplanarity and hindered rotation have been discussed based on chemical shifts and shapes of the C¹, C² and C³ signals.