Novel Approach to the Synthesis of 3-amino-4-arylpyridin-2(1H)-one Derivatives

Abstract

The reaction of 4-arylidene-2-phenyloxazol-5(4 H )-ones with enamines of ethyl acetoacetate gave 4-aryl-2-methyl-6-oxo-5-[(phenylcarbonyl)amino]-1,4,5,6-tetrahydropyridine-3-carboxylic acid esters, which, when heated with phosphorus oxychloride, were converted into esters of 7-aryl-5-methyl-2-phenyloxazolo[5,4- b ]pyridine-6-carboxylic acids. Alkaline hydrolysis of these compounds gave 4-aryl-2-methyl-6-oxo-5-[(phenylcarbonyl)amino]-1,6-dihydropyridine-3-carboxylic acid esters. Supplementary Information The online version contains supplementary material available at 10.1007/s10593-021-02980-w.

New one-pot synthesis of 4-arylpyrazolo[3,4-b]pyridin-6-ones based on 5-aminopyrazoles and azlactones

“…One of the rational approaches to the synthesis of fused pyridine derivatives is based on the domino reaction of enamines with azlactones [22][23][24][25][26][27][28][29][30]. We have previously reported a plausible mechanism of such reactions [22,25].…”

Synthesis of 3‐Aminopyrido[2,1‐a]isoquinolin‐4‐one Derivatives via Condensation of Azlactones with 1‐Alkyl‐3,4‐dihydroisoquinolines

“…The known methods for the synthesis of 3‐amino‐6,7‐dihydro‐4 H ‐pyrido[2,1‐ a ]isoquinolin‐4‐ones include multistep reactions [19] . A possibility to obtain 3‐aminopyridine‐2(1 H )‐one derivatives by reacting enamines with azlactone 5 has been previously reported [20a–h] …”

New Synthesis of Pyrazolo[3,4-b]pyridine Derivatives Based on 5-Aminopyrazole and Azlactones

“…10 In order to obtain 1,4-dihydropyridine derivatives 4a – i , we studied the possibility of oxazole ring closure by heating amides 3a – i with POCl 3 . 7c 11 4-Aryloxazolo[5,4- b ]pyrazolo[4,3- e ]pyridines 5a – i were formed as a result of oxidation of the intermediate dehydro derivatives 4a – i with atmospheric oxygen. The yield of compounds 5a – i ranged from 43 to 77%.…”

“…The quantum yield of examined compounds was determined relative to quinine sulfate in 0.5 M H 2 SO 4 (Φ f = 0.546) known quantum yield standard, using the comparative method. 7c 15 NMR spectra ( 1 H and 13 C) were measured in solutions of DMSO- d 6 , CF 3 CO 2 D or CDCl 3 on a Bruker DRX-400 spectrometer (working frequencies 400 and 100 MHz, respectively). All chemical shifts (δ) are reported in ppm and coupling constants ( J ) in Hz.…”