β-Enamino Esters in Heterocyclic Synthesis: Synthesis of Pyrazolone and Pyridinone Derivatives

Abstract

An efficient and convenient synthesis of pyrrolidinones and pyridinones utilizing enamino esters as starting material has been described. The structures of the compounds obtained were confirmed by spectral and elemental analyses.

Enaminonitriles in Heterocyclic Synthesis: A Route to 1,3-Diaryl-4-aminopyrazole Derivatives

“…In conjunction to our interest in chemistry of pyrazoles [15,16,17] and condensed pyrazoles [18,19,20] we decided to develop an efficient route to the title compounds. A logical route to these compounds would be the reaction of hydrazones 1a , f with functionally substituted alkyl halides to yield targeted compounds 3 via intermediate 2 .…”

“…We have decided to test the possibility that enaminonitriles 11 can couple with aromatic diazonium salts to yield intermediates 12 that would be readily converted into 13 and consequently into 1d – f [23] via a Japp-Klingmann cleavage [24], a similar coupling process that has been previously reported by us [15]. …”

A Simple, Efficient Green Protocol for the Synthesis of β‐Enaminone and Enamino Ester Derivatives by Using Onion Extract as Green Catalyst

“…The most well‐known and exploited route to β‐enaminones 3 involves the direct condensation of β‐dicarbonyl compounds 1 with amines 2 in refluxing aromatic hydrocarbons with azeotropic removal of water. Other improved procedures have also been subsequently reported which include the reaction of amines 2 with β‐dicarbonyl compounds 1 supported on AcOH under ultrasound, CoCl 2 .6H 2 O, CAN, microwave irradiation, TMSTf, Zn(OAc) 2 .2H 2 O, K 2 HPO 4 , InBr 3 , [(PPh 3 )AuCl]/AgOTf, silica gel, HClO 4 ⋅SiO 2 , Bi(TFA) 3 , NaAuCl 4 , ZrOCl 2 .8H 2 O, catalyst free, solvent free‐ grinding, NaHSO 4 /SiO 2 , LiHSO 4 /SiO 2 , Ni(OAc) 2 , copper catalyst, CuBr 2 /L 2 /pyrrolidine, CuI, mesoporous alumina sulphuric acid, water‐lactic acid, L‐proline, silica‐supported antimony(III) chloride, clays, LaCl 3 , MW/K‐10 or MW/KSF, DMF/DMA, Ag/HMMS, PPA‐SiO 2 , ionic liquids based, nano fibrous silica sulphuric acid (KCC‐1‐SA) . Unfortunately many of these processes are have major or minor limitations such as drastic reaction conditions, prolonged reaction time, high temperature, low yields and tedious work‐up procedures.…”

Synthesis of New Bis(3-hydroxy-4-pyridinone) Ligands as Chelating Agents for Uranyl Complexation

“…Among the different chelators, 3-Hydroxy-4-pyridinones (3,4-HOPO) have emerged as one of the hotspots in studies that focus on heavy metal chelators because of their special bidentate structure, highly selective chelating capacity, and significant physiological activities [5,6,7,8,9,10,11,12]. To date, three kinds of 3,4-HOPO derivatives are available, namely bidentate hydroxypyridinones [5,6], tetradentate hydroxypyridinones [7,8,9], and hexadentate hydroxypyridinones [10,11].…”