A regioselective and efficient approach toward 6-amino-5-benzoyl-1-substituted 2(1H)-pyridinonesby reaction of acyclic ketene aminals with propiolic acid ester was developed. The effect of thesolvent and temperature on the regioselectivity of the reaction and the compatibility of the targetcompounds to functional group manipulations was examined. Substrates with an ortho substituentbuild atropisomers due to the restricted rotation around the C−N bond. The enantiomers wereseparated, and the barrier of rotation was determined experimentally. Quantum chemicalcalculations allowed a ranking of the barrier heights, and a new mechanism of rotation bydeformation of the central pyridinone moiety is proposed.