SYNTHESIS AND ANTIMICROBIAL SCREENING OF SOME NEW 4-IMINO-3,5,7-TRISUBSTITUTED PYRIDO[2,3-d]PYRIMIDINES AND THEIR RIBOFURANOSIDES AS POTENTIAL CHEMOTHERAPEUTIC AGENTS

Some new nucleosides, viz. 4-imino-3,5,7-trisubstituted-1-(2′,3′,5′-tri-O-kbenzyl–β-D-ribofuranosyl)pyrido[2,3-d]pyrimidin/e–2(1H)-ones/ thiones(VII/VIII), have been synthesized by condensation of trimethylsilyl derivatives of 4-imino-3,5,7-trisubstituted pyrido[2,3-d]pyrimidin/e-2(1H)-ones/thiones (III/IV) with β-D-ribofuranosyl1-acetate-2,3,5-tribenzoate. Compounds III/IV have been synthesized by refluxing 2-amino-3-cyano-4,6-disubstituted pyridine (II) with substituted an arylisocyanate or an isothiocyanate respectively. The structure of all the synthesized compounds have been established by IR and ¹H NMR studies. These compounds have been screened for antimicrobial activities in order evaluate. The possibility of the derivatives to be used as potential chemotherapeutic agents.     

Biginelli-type reaction: Efficient synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2-ones and thiones from gem-dibromomethylarenes

In the present study, we are reporting a simple and efficient method for the one-pot synthesis of the biologically important heterocyclic molecules 5-unsubstituted 3,4-dihydropyrimidin-2-ones and thiones using gem-dibromomethylarenes, oxalacetic acid, and urea or thiourea. Gem-dibromomethylarenes are used as aldehyde equivalent for the efficient synthesis of 3,4-dihydropyrimidin-2-ones/thiones. This reaction offers advantages for the synthesis of these compounds, including ready availability of the starting materials, experimental simplicity and in good yields. Besides, the synthesized molecules are interesting for their biological and pharmacological actions.     

SYNTHESIS,REACTIONS AND SPECTRAL PROPERTIES OF 3-CHLORO-2,6DIARYL-4H-THIOPYRAN-4-ONES. SYNTHESIS OF SOME NEW 3-CHLORO-SPIROTHIOPYRAN DERIVATIVES

3-Chloro-2-phenyl-6-p-tolyl and 3-chloro-2,6-di-p-tolyl-4H-thiopyran-4-ones have been synthesized in moderate yieldes from the reaction of 3-chloro-tetrahydrothiopyran-4-ones with phosphorus pentachloride. Their thiones, oximes, and hydrazones have been also prepared. Treatment of thiones with malononitrile gave the corresponding 3-chloro-4-thiopyrylidenemalononitriles which gave 3-chloro-spirothiopyran derivatives of pyrazole, isoxazole, 1,3-thiazines when treated with hydrazine hydrate, hydroxylamine hydrochloride, thiourea and thiosemicarbazide, respectively. While treatment of 3-chloro-thiopyrylidene-malononitriles with acetylacetone gave the corresponding 3-chloro-spirothiopyran derivatives of pyran.     

Melamine trisulfonic acid:A new,efficient and recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones in the absence of solvent

Melamine trisulfonic acid(MTSA) can be used as an efficient and recyclable catalyst for the promotion of the synthesis of 3,4- dihydropyrimidin-2(1H)-ones/thiones(DHPMs) in the absence of solvent.All reactions were performed at 80℃in good to high yields.     

A PTC ASSISTED THIONATION: SYNTHESIS OF 2H-1,4- BENZOXAZINE-3(4H)-THIONES & 2h-1,4-BENZOTHIAZINE- 3(4H)-THIONES

A facile method for the conversion of 2H-1,4-benzoxa/thiazine-3(4H)-ones to their respective thiones under PTC (P₂S₅/K₂CO₃/TEBA) conditions is reported.     

Silica-bonded N-propyl sulfamic acid as an efficient recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones/thiones under heterogeneous conditions

Silica-bonded N-propyl sulfamic acid(SBNPSA) catalyzed one-pot three component Biginelli condensation of different substituted aromatic aldehydes with ethyl acetoacetate and urea/thoiurea to the respective 3,4-dihydropyrimidin-2-(1H)-ones and thiones in environment friendly procedure is described. The facile reaction conditions, simple isolation and purification procedures of this method make it a good option for the synthesis of dihydropyrimidinones.     

First Example of the Synthesis of Di(fluoroalkyl)-substituted Pyrimidines

4,5-Bis(hydroxy)-4-trifluoromethyl-6-(fluoroalkyl)hexahydropyrimidin-2-ones (thiones) have been obtained for the first time by the reaction of ureas (thioureas) with di(fluoroalkyl)-substituted 1,3-diketones and tetraols, the dehydration of which gave 2-hydroxy(mercapto)-4-trifluoromethyl-6-(fluoroalkyl)pyrimidines.     

Domino reactions in the synthesis of tetrahydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones(thiones) annelated at the N(1)–C(6) bond (Review)

Information relating to the synthesis of tetrahydropyrimidin-2(1H)-ones(thiones), annelated at the N(1)–C(6) bond, by cascade cyclization of substituted N-(3-oxoalkyl)ureas and thioureas is classified. The general relationships of this process are presented.     

N-Substituted benzoxazolyl ureas and thioureas in Biginelli reaction promoted by trifluoromethane sulfonic acid:An efficient and convenient synthesis of substituted benzoxazolyl 3,4-dihydropyrimidine(1H)-(thio)-ones

An efficient synthesis of 3,4-dihydropyrimidine 2(1H)-ones and thiones(3,4-DHPMs) core was prepared by one-pot threecomponent Biginelli condensation and which was catalyzed by trifluoromethane sulfonic acid.The classical Bignelli reaction has been extended by the use of N-substituted benzoxazolyl semicarbazides and thiosemicarbazides and this method has the advantage of excellent yields and short reaction times.     

Synthesis and alkylation of new 3-functionally substituted carbo[c]fused pyridin-2-ones(thiones)

By condensation of 2-acyl-1-(morpholin-4-yl)cycloalkenes with CH-acids new 3-functuinally substituted carbo[c]fused pyridin-2-ones(thiones) were synthesized. N, 1-Diphenyl-5, 6, 7, 8-tetrahydroisoquinoline-3-thione under the action of acrylonitrile and alkyl halides suffered a selective S-alkylation.     

Composés sulfurés hétérocycliques. CII. Action de l'hydroxylamine sur les dihydro-1,2 benzothiazine-3,1 thiones-4

Hydroxylamine reacts with 1-alkyl-1,2-dihydro-3,1-benzothiazine-4thiones ( 1 ), giving 1-alky1-3-hydroxy-2,3-dihydro-1H-quinazoline-4-thiones ( 2 ). The same reagent, in neutral medium, converts 1-aryl-1,2-dihydro-3,1-benzothiazine-4-thiones ( 3 ) into 1-aryl-4-hydroxyimino-1,4-dihydro-2H-3,1-benzothiazines ( 4 ). In acidic medium, the same starting materials lead to 1-aryl-3-hydroxy-2-3-dihydro-1H-quinazoline-4-thiones ( 5 ). genrally with some quantity of the isomer 4 . Thiones 2 and 5 , as well as oximes 4 , heated at 200°, decomopose, yielding, in varying proportions, 1H-quinazoline-4-thiones ( 6 or 7 ), 1H-quinazoline-4-ones ( 9 ) and 2,3-dihydro-1H-quinazoline-4-thiones ( 11 ). Reacting with methyliodide, 1H-quinazoline-4-thiones ( 7 ) give 4-methylthioquinazolin-1-ium iodidies ( 12 ) which can be hydrolysed into 1H-quinazolin-4-ones ( 9 ). The latter are also obtained by reacting benzonitrile N-oxide with the corresponding thiones. 1-Aryl-1 H-quinazoline-4-thiones ( 7 ) react readily with nitrogen nucleophiles XNH₂ to give 1-aryl-4-imino-1,4-dihydro-quinazolines diversely substituted on the imino group. While thiones 7 are S- methylated by methyl iodide, the corresponding 1-aryl-1H-quinazolin-4-ones (9), with the same reagent, ungergo a N-methylation, yielding 1-aryl-3-methyl-4-oxo-3,4-dihydroquinazolin-l-ium iodides ( 18 ). Structure have been confirmed by uv, ir and nmr spectra.     

1-Sulfopyridinium chloride:Green and expeditious ionic liquid for the one-pot synthesis of fused 3,4-dihydropyrimidin-2(1H)-ones and thiones under solvent-free conditions

1-Sulfopyridinium chloride portrayed as an efficient and recyclable ionic liquid for the synthesis of fused3,4-dihydropyrimidin-2(1H)-ones and thiones via a modified Biginelli reaction involving one-pot three component condensation of 6-methoxy-1-tetralone,arylaldehydes and urea/thiourea under solventfree conditions.Analytically pure products are formed within 10–20 min in excellent yields.     

A novel and efficient one-pot method to Biginelli-like scaffolds

A novel and efficient one-pot method for the preparation of fused ring 3,4-dihydropyrimidin-2(1H)-ones and thiones from cyclocondensation of aldehydes, cyclic ketones and urea or thiourea using a catalytic amount of cupric chloride under mild conditions reaction is described. This new method has the advantage to give high yields, to be completed in short reaction times and simple product isolation procedure.     

A rapid and convenient synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2-ones and thiones

A rapid and convenient synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2-ones and thiones was developed. The reaction involves a one-pot reaction between oxalacetic acid, thiourea/urea, and aldehyde under microwave irradiation and provides the products in good yields and much shorter reaction times.     

4,5-Dihydroxyimidazolidin-2-ones in an α-ureidoalkylation reaction of N-(carboxyalkyl)-, N-(hydroxyalkyl)-, and N-(aminoalkyl)ureas 3. α-Ureidoalkylation of N-[2-(dimethylamino)ethyl]urea

α-Ureidoalkylation of N-[2-(dimethylamino)ethyl]urea with 1,3-unsubstituted, 1,3-dialkyl-, and 1,3-dimethyl-4,5-diphenyl-4,5-dihydroxyimidazolidin-2-ones(thiones) was systematically studied. Hitherto unknown N-[2-(dimethylamino)ethyl]glycolurils and their hydrochlorides were synthesized. The yields of the target glycoluril hydrochlorides decreased on going from 1,3-H₂- to 1,3-dialkyl-4,5-dihydroxyimidazolidin-2-ones and increased with the introduction of phenyl groups at the positions 4 and 5 of the starting 4,5-dihydroxyimidazolidin-2-one. X-ray diffraction study showed that 2-[2-(dimethylamino)ethyl]glycoluril crystallizes in the form of a conglomerate.     

Ultrasound-Mediated Synthesis of 3,4-Dihydropyrimidin-2-(1H)-Ones (or Thiones) with NaHSO4·H2O

Abstract

A fast and efficient Biginelli synthesis of 3,4-dihydropyrimidin-2-(1H)-ones (or thiones) by the reaction of aromatic aldehydes, β-dicarbonyls, and urea/thiourea using NaHSO₄·H₂O/ultrasound system is presented. The reactions were carried out in refluxing n-hexane/CH₃CN (2.5:0.5 mL) to afford the products in excellent yields.     

Potassium phthalimide： An efficient and green organocatalyst for the synthesis of 4-aryl-7-（arylmethylene）-3,4,6,7-tetrahydro-1H- cyclopenta[d]pyrimidin-2（5H）-ones]thiones under solvent-free conditions

An efficient synthesis of Biginelli-type compounds using potassium phthalimide as a green, mild, and commercially available organocatalyst in a one-pot, multi-component cyclocondensation reaction of cyclopentanone, aldehydes, and urea/thiourea is reported. The present methodology is a green approach to access 4-aryl-7-（aryImethylene）-3,4,6,7-tetrahydro-1H-cyclopenta[d]pyrimidin-2（5H）-ones/thiones. It offers several merits such as simple operational procedures, no use of hazardous organic solvents, and cheap and environmentally friendly solid basic catalyst.     

Three component reactions：An efficient and green synthesis of 3, 4-dihydropyrimidin-2-(1H)-ones and thiones using silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate

An environmentally benign aqueous protocol for the synthesis of 3,4-dihydropyrimidin-2-(1H)-ones and thiones promoted by a green catalyst,silica gel-supported L-pyrrolidine-2-carboxylic acid-4-hydrogen sulfate,has been developed.The use of nontoxic,thermally stable and inexpensive amino acid catalyst makes the process simple with minimal amount of chemical waste.Compared with classical Biginelli reaction conditions,this new method has the advantages of high yields and simple workup procedures.     

Advances in Biginelli reaction: A comprehensive review

The Biginelli reaction, a conventional three-component reaction provides 3,4-dihydropyrimidin-2(1H)-ones/thiones via one-pot acid catalyzed cyclocondensation of an aldehyde, a β-keto ester, and urea or thiourea. Dihydropyrimidones are well-known scaffolds having a wide range of pharmacological activities. So far classical Biginelli reaction has witnessed several modification and studies are still continuing in this field to develop greener and efficient methodologies. In this review, we summarize the recent advances in Biginelli reaction covering literature from 2020 to 2023.     

A Study of the behaviour of an analogous series of 2H-thiopyrans, 6H-1,3-thiazines and their derivatives by carbon-13 and nitrogen-15 nuclear magnetic resonance

The influence of substituents in a new series of 2H-thiopyrans, 2H-thiopyran-2-ones (thiones) and their thiazine analogues is examined by means of carbon (¹³C) and nitrogen (¹⁵N) NMR. A linear relationship is shown to exist between the chemical shifts (δ_13C or δ_15N) of the thiopyrans and the thiazines. This relationship is a good indication of the structural similarity which exists between the two series.