A Versatile and Efficient Synthesis of 2‐Alkyl and 2‐Aryl‐6‐alkyl‐2,3‐dihydro‐1H‐pyridin‐4‐ones.

Synthesis of 2,3-Dihydro-4-pyridones and 4-Pyridones by the Cyclization Reaction of Ester-Tethered Enaminones

“…The first approach involves the addition of organometallic reagents to N -acyl salts of 4-methoxypyridine, developed by Comins,e.g., dehydrogenation of the corresponding saturated heterocycle, conjugate addition of the Grignard reagent on N -carbamoyl-4-pyridones, and reaction of 2,3-dihydropyran-4-ones with ammonia and primary amines . The second approach includes reactions of imines with dienes; cyclizations of primary amines with α,ß-unsaturated-1,3-diketones, dienones, and α-alkenoyl ketene dithioacetals; cyclizations of nitrogen-containing ynones; , reactions of amino esters with β-keto esters; [5 + 1] cycloaddition of N -formylmethyl-substituted tertiary enamides to isocyanides; [4 + 2] cycloaddition of 3-phenylcyclobutanones with nitriles; and cyclizations involving enaminones …”

“…As part of our project is directed toward the synthesis of enaminones and their utilization as synthetic intermediates, we wish to report the synthesis of 2,3-dihydro-4-pyridones via an intramolecular cyclization involving the C–C bond formation (Figure ). The open-chain enaminone, used as a precursor for the heterocycle, resembles that of ref b (prepared from β-amino esters and β-keto esters) but cannot be simply cyclized under basic conditions because it lacks the acidic N–H group of the enaminone moiety enabling carbanion formation. Instead, the reaction has to be based on the nucleophilicity of the olefinic carbon atom and the cyclization leads to a N-substituted dihydropyridone ring.…”

5-Hydroxyindole-Based EZH2 Inhibitors Assembled via TCCA-Catalyzed Condensation and Nenitzescu Reactions

“…To date, various protocols have been developed for its preparation [9][10][11][12][13], among which the Nenitzescu indole synthesis where 1,4-benzoquinone is condensed with enamines to afford N-substituted 5-hydroxyindoles has been proven to be the simplest strategy [14]. The related enamines are ubiquitous reagents in organic synthesis [15][16][17], which are generally obtained by condensation reaction using amines, β-diketones or β-ketoesters as starting materials [18][19][20][21].…”

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

“…Since dihydropyridones belong to a class of cyclic enaminones, a convenient strategy for the synthesis of these nonaromatic heterocycles involves the reaction of acyclic enaminones with α,β-unsaturated acid chlorides, the enaminone cyclization via Dieckman condensation, or generation of ketenes from diazo ketones (Scheme ). Besides, the approach based on the in situ formation of possible enaminone intermediates has been reported to be the multicomponent transformation of 3,5-dioxohexanoate with aromatic aldehydes and ammonium acetate leading to N -unsubstituted trans -dihydropyridones .…”