Synthesis of Multifunctionalized 2,3-Dihydro-4-pyridones and 4‑Pyridones via the Reaction of Carbamoylated Enaminones with Aldehydes

The novel and effective diastereoselective
synthesis of multifunctionalized
dihydropyridones, including CF3-substituted derivatives,
has been developed on the basis of the piperidine-promoted domino
reaction of carbamoylated enaminones with aldehydes. The products
have been prepared in 38–90% yields and can be easily isolated
by crystallization. Tautomerism, epimerization, and atropisomerism
of dihydropyridones have been studied. The use of the resulting dihydropyridones
in the synthesis of 1,2,6-trisubstituted 4-pyridone-3-carboxamides
has been demonstrated via oxidative aromatization initiated by iodine.