for the Synthesis of 4,6-disubstituted- 3-cyano-2-pyridones and 4 ..
A series of some novel arylazo pyridone dyes was synthesized from the corresponding diazonium salt and 6-hydroxy-4-phenyl-3-cyano-2-pyridone using a classical reaction for the synthesis of the azo compounds.
Synthesis of 4, 6- Dimethyl-3-cyano-2-pyridone
In this work, the synthesis of twelve new 5-arylazo-6-hydroxy-4-phenyl-3-cyano-2-pyridones (Scheme ), their UV-vis absorption spectra (200–600 nm) in thirteen solvents of different polarity and the relationship between color and the constitution of these dyes are reported. The effects of the solvent and the substituent on the azo-hydrazone tautomeric equilibrium, and the geometry data of the investigated dyes, obtained using DFT quantum-chemical calculations, were studied and evaluated.
The synthetic procedures adopted to obtain the test compounds are depicted in and . Chlorination of 5-bromo-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile 1 with PCl5 in POCl3 afforded 2-chloropyridine derivative 2,) which was cyclized under the effect of hydrazine hydrate in boiling ethanol yielded the amine derivative 4 instead of 5-bromo-2-hydrazinyl-4,6-dimethylnicotinonitrile 3.,) Reaction of 1 with phenyl isothiocyanate in dry dimethylformamide (DMF) containing a catalytic amount of triethylamine (TEA) gave 5-bromo-3-cyano-4,6-dimethyl-2-oxo--phenylpyridine-1(2)-carbothioamide 5 ().
2-Pyridone catalyses a variety of proton-dependent reactions, ..
Sodium triacetoxyborohydride is presented as a general reducing agent for the reductive amination of aldehydes and ketones. Procedures for using this mild and selective reagent have been developed for a wide variety of substrates. The scope of the reaction includes aliphatic acyclic and cyclic ketones, aliphatic and aromatic aldehydes, and primary and secondary amines including a variety of weakly basic and nonbasic amines. Limitations include reactions with aromatic and unsaturated ketones and some sterically hindered ketones and amines. 1,2-Dichloroethane (DCE) is the preferred reaction solvent, but reactions can also be carried out in tetrahydrofuran (THF) and occasionally in acetonitrile. Acetic acid may be used as catalyst with ketone reactions, but it is generally not needed with aldehydes. The procedure is carried out effectively in the presence of acid sensitive functional groups such as acetals and ketals; it can also be carried out in the presence of reducible functional groups such as C−C multiple bonds and cyano and nitro groups. Reactions are generally faster in DCE than in THF, and in both solvents, reactions are faster in the presence of AcOH. In comparison with other reductive amination procedures such as NaBH3CN/MeOH, borane−pyridine, and catalytic hydrogenation, NaBH(OAc)3 gave consistently higher yields and fewer side products. In the reductive amination of some aldehydes with primary amines where dialkylation is a problem we adopted a stepwise procedure involving imine formation in MeOH followed by reduction with NaBH4.
Synthesis, properties and color assessment of some new …
(2003 ) An efficient method for the synthesis of 3-cyano-6-hydroxy-2- pyridones under microwave irradiation and solvent-free conditions 134 ,453-457.