Substituted pyridopyrimidinones, 1: Convenient PTC alkylation and halogenation of 2‐hydroxy‐4H‐pyrido[1,2‐a]pyrimidin‐4‐one

Abstract

Alkylation of 2-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one (1) was investigated under solidliquid phase transfer catalysis conditions (PTC), using tetrabutylammonium bromide and potassium carbonate. The reaction with alkyl halides led to the formation of various 2-alkoxy products, in fair yields. Reaction of compound 1 with

Synthesis of Heteroannulated Chromeno[2,3‐b]Pyridines: DBU Catalyzed Reactions of 2‐Amino‐6‐methylchromone‐3‐Carboxaldehyde with Some Heterocyclic Enols and Enamines

“…4‐Hydroxycoumarin ( 2 ) and 4(6)‐aminouracil were supplied by Merck and 5‐amino‐3‐methyl‐1 H ‐pyrazole by Aldrich. 4‐Hydroxy‐1‐methylquinolin‐2(1 H )‐one ( 4 ) , 2‐hydroxy‐4 H ‐pyrido[1,2‐ a ]pyrimidin‐4‐one ( 6 ) , and 4‐hydroxy‐2 H ‐pyrano[3,2‐ c ]quinoline‐2,5(6 H )‐dione ( 8 ) were prepared according to literature.…”

“…and 4(6)-aminouracil were supplied by Merck and 5-amino-3methyl-1H-pyrazole by Aldrich. 4-Hydroxy-1-methylquinolin-2(1H)-one (4)[27], 2-hydroxy-4H-pyrido[1,2-a]pyrimidin-4-one (6)[28], and 4-hydroxy-2H-pyrano[3,2-c]quinoline-2,5(6H)dione(8) [27] were prepared according to literature.10-Methyl-6H,8H-dichromeno[2,3-b:3′,4′-e]pyridine-6,8dione(3). A mixture of 2-amino-6-methylchromone-3-carboxaldehyde (1), (0.61 g, 3 mmol) and 4-hydroxycoumarin (2), (0.49 g, 3 mmol), in DMF (10 mL) containing a few drops of DBU, was heated under reflux for 2 h. The yellow crystals obtained after cooling were filtered off and crystallized from DMF/H 2 O to give compound 3 as yellow crystals, mp > 300°C, yield 0.53 g (54%).…”

Substituted Pyridopyrimidinones. Part 3. Synthesis of Some Novel Ether Derivatives of 4H-Pyrido[1,2-a]pyrimidin-4-one

“…For example, this structural pattern is present in the known psychotropic agents risperidone and paliperidone [2,3], the human leukocyte elastase inhibitor SSR69071 [4], the antiallergic agent ramastine [5], and the antioxidants 2-arylpyrido[1,2-a]pyrimidin-4-ones [6] (Figure 1). As a continuation to our previous work [7], we utilized ethyl [(4-oxo-4H-pyrido[1,2-a]pyrimidin-2yl)oxy]acetate (1) to obtain novel bi-heterocyclic ethers which are of expected antipsychotic activity. This expected biological activity may be due to the presence of pyridopyrimidinone and other known biologically active heterocycles such as pyrazole, imidazole, triazole, oxadiazole, pyrone, coumarin, and quinolinone in one-molecular frame [8,9].…”

Substituted pyridopyrimidinones, Part IV: 2-chloro-4h-pyrido[1,2-a]pyrimidin-4-one as a synthone of some new heterotricycles

“…1 It is well-known that this type of α-haloheterocyclic compounds are susceptible to synthetically important nucleophilic substitutions. [2][3][4][5] Many hetero-fused pyrimidines exhibit attractive cancer chemotherapy properties as antitumor agents.…”