A convenient synthesis of 5‐(O,O‐dialkylphosphoryl)‐4‐aryl‐3,4‐dihydropyrimidin‐2(1H)‐ones

A general and convenient route for the synthesis of dihydropyrimidines bearing the phosphoryl moiety by a one‐pot cyclocondensation involving aldehydes, urea, and O,O‐dialkyl‐2‐oxo‐propanephosphonates, using ytterbium triflate as catalyst, is reported. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:13–17, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10058     

Convenient synthesis and biological activities of pyridine derivatives of 3,4‐dihydropyrimidin‐2(1H)‐ones

2‐Chloro‐5‐(chloromethyl)‐pyridine reacted with 3,4‐dihydropyrimidin‐2(1H)‐ones 1 to afford 1‐[6‐aryl‐1‐(6‐chloropyridin‐3‐yl‐methyl)‐2‐(6‐chloropyridin‐3‐yl‐methylthio)‐4‐methyl‐1,6‐dihydropyrimidin‐5‐yl] carboxylates or ethanones 2 in good yields. The structure of the target compounds 2 was confirmed by IR, ¹H NMR, EI‐MS, and elemental analyses, and compound 2a was further characterized by single crystal X‐ray diffraction. The preliminary bioassay indicated that some of the title compounds possess moderate insecticidal and fungicidal activities. J. Heterocyclic Chem., (2011).     

Dichloro dicyano quinone (DDQ) as coupling reagent for high yield synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones

DDQ catalyzes efficiently the three‐component condensation reaction of aldehyde, β‐ketoester and urea in refluxing acetonitrile to afford the corresponding dihydropyrimidinones. Compared to the classical Biginelli reaction conditions, this new approach consistently has the advantage of excellent yields (80‐92%) and short reaction times 1.5‐2.5 h.     

Zirconium (IV) porphyrin graphene oxide: a new and efficient catalyst for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones

A covalently cross‐linked graphene oxide (GO) as a catalyst was prepared by a cross‐linking process using the nucleophilic reaction of zirconium (IV)‐coordinated 5,10,15,20‐tetrakis (aminophenyl)porphyrin (ZrPPh) with carboxyl groups of the edges of GO (GO‐ZrPPh). The chemical structure of catalyst was characterized by different analyses such as FT‐IR, SEM, TEM, EDS, ICP, TGA and UV. All analyses confirm the occurrence of successfully covalent immobilization of ZrPPh on the GO. Also, TEM and SEM images show that ZrPPh has been immobilized in the both of the edges and the basal plane of GO. The activity of the catalyst was studied for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones via Biginelli reaction. The cross‐linked catalyst is able to catalyze the reaction in short reaction times and good to excellent yields.     

An efficient and modified biginelli one‐pot synthesis of new isoxazole substitted 3,4‐dihydropyrimidin‐2(1H)‐ones and thiones catalyzed by VCl3

An efficient and modified Biginelli one‐pot synthesis of new‐isoxazole substituted 3,4‐dihydropyrimidin‐2(1H)‐ones and thiones from aromatic aldehydes, ketoamide and urea/thiourea in acetonitrile using VCl₃ as the catalyst is described.     

3‐(α‐Chlorobenzyl)quinoxalin‐2(1H)‐ones as Versatile Reagents for the Synthesis of 3‐Benzylquinoxalin‐2(1H)‐ones and Thiazolo[3,4‐a]quinoxalin‐4(5H)‐ones

Facile and efficient methods for the synthesis of 3‐benzylquinoxalin‐2(1H)‐ones and thiazolo[3,4‐a]quinoxalin‐4(5H)‐ones by the reaction of the readily available 3‐(α‐chlorobenzyl)quinoxalin‐2(1H)‐ones and thiourea have been developed, with multiple roles of the latter. Possible mechanisms are discussed. These two‐step sequences can be performed in a one‐pot manner to produce the desired products in moderate to high yields.     

Ruthenium‐catalyzed biginelli condensation: A simple and efficient one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones under mild reaction conditions

Ruthenium trichloride was found to be an efficient catalyst for the first time for the synthesis of a variety of 3,4‐dihydropyrimidin‐2(1H)‐ones by cyclocondensation of an aldehyde, β‐dicarbonyl compound and urea in excellent yields under mild reaction conditions.     

Imidazolium‐based phosphinite ionic liquid as reusable catalyst and solvent for one‐pot synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ (thio)ones

A mild and efficient procedure for the synthesis of 3,4‐dihydropyrimidin‐2(1H)‐(thio)ones in phosphinite ionic liquid is described. This ionic liquid plays a dual role as both the reaction media and also a catalyst, which can be easily recovered and reused in several runs. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:284–288, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20549     

Oxalic acid as a versatile catalyst for one pot facile synthesis of 3,4‐dihydropyrimidin‐2‐(1H)‐ones and their thione analogues

3,4‐Dihydropyrimidin‐2‐(1H)‐ones and their thione analogues are synthesized from the condensation of aromatic aldehydes, β‐dicarbonyl compound and urea or thiourea in presence of 5 mol% of oxalic acid in ethanol‐water (1:2; v/v) under mild reaction conditions. The yields obtained are better and also the use of very inexpensive catalyst, environmentally benign solvent and easy work‐up are the advantageous aspects of the present method.     

Synthesis of New Furo[3,4‐b]quinolin‐1(3H)‐one Scaffolds Derived from γ‐Lactone‐Fused Quinolin‐4(1H)‐ones

In the context of our aim of discovering new antitumor drugs among synthetic γ‐lactone‐ and γ‐lactam‐fused 1‐methylquinolin‐4(1H)‐ones, we developed a rapid access to 5‐methyl‐1,3‐dioxolo[4,5‐g]furo[3,4‐b]quinoline‐8,9(5H,6H)‐dione ( 9 ) exploiting the γ‐lactone‐fused chloroquinoline 10 previously synthesized in our laboratory (Scheme 1). We also elaborated efficient synthetic methods allowing for a rapid access to two nonclassical bioisosteres of 9 , i.e., a deoxy and a carba analogue. The deoxy analogue 11 was prepared in two steps from the γ‐lactone‐fused quinoline 13 which was also the synthetic precursor of 10 (Scheme 1). The carba analogue 6,9‐dihydro‐5‐methyl‐9‐methylene‐1,3‐dioxolo[4,5‐g]furo[3,4‐b]quinolin‐8(5H)‐one ( 12 ) was easily prepared by HCl elimination from the 9‐(chloromethyl)dioxolofuroquinoline 15 , which was obtained via a three‐component one‐pot reaction from N‐methyl‐3,4‐(methylenedioxy)aniline (=N‐methyl‐1,3‐benzodioxol‐5‐amine; 16 ), commercially available chloroacetaldehyde, and tetronic acid ( 17 ) (Scheme 2).     

An efficient protocol for the one‐pot synthesis of 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones catalyzed by Mg(NO3)2

A series of novel 4‐(2‐(4‐bromophenyl)‐1,2,3‐triazol‐4‐yl)‐3,4‐dihydropyrimidin‐2(1H)‐ones/thiones were prepared by condensing 2‐(4‐bromophenyl)‐4‐formyl‐1,2,3‐triazole with 1,3‐dicarbonyl compound and urea or thiourea using Mg(NO₃)₂ as an efficient and cheap catalyst. The satisfactory results were obtained with excellent yields and short reaction time. J. Heterocyclic Chem., (2010).     

A novel synthesis of 1‐substituted 2H‐isoquinolin‐3‐ones

The intramolecular cyclization of 2‐acylphenylacetonitriles 1 under strongly acidic conditions easily affords 1‐substituted 2H‐isoquinolin‐3‐ones 2 in excellent yields.     

Synthesis of 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐ ones and their remarkably facile recyclization to 2,3‐dihydropyrimidin‐4(1H)‐ones

Functionalized 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐one derivatives have been synthesized by cyclocondensation of 3‐alkyl(aryl)amino‐2‐cyano‐3‐mercaptoacrylamides with aldehydes and ketones under acidic catalysis. 6‐Alkyl(aryl)amino‐5‐cyano‐2,3‐dihy‐ dro‐1,3‐thiazin‐4(1H)‐ones, when treated with a dilute solution of potassium hydroxide, are converted into the potassium salts of isomeric compounds, 1‐alkyl‐ (aryl)‐5‐cyano‐6‐mercapto‐2,3‐dihydropyrimidin‐ 4(1H)‐ones. Alkylation of the latter with dimethyl sulfate in situ furnishes 1‐alkyl(aryl)‐6‐alkylthio‐5‐ cyano‐2,3‐dihydropyrimidin‐4(1H)‐ones, whereas boiling them in ethanol with an excess of hydrochloric acid leads to starting 2,3‐dihydro‐1,3‐thiazin‐4(1H)‐ones. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:426–436, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20129     

A novel stereoselective synthesis of (Z)‐α‐arylsulfanyl‐α,β‐unsaturated ketones via Stille coupling of (E)‐α‐arylsulfanylvinylstannanes with acyl halides

(E)‐α‐Arylsulfanylvinylstannanes react with acyl halides in the presence of a catalytic amount of Pd(PPh₃)₄ and CuI cocatalyst to give stereoselectively the corresponding (Z)‐α‐arylsulfanyl‐α,β‐unsaturated ketones in good yields. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:218–223, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20536     

A convenient synthesis of certain 1-(β-D-ribofuranosyl)benzotriazoles

The synthesis of 5,6-dichloro-1-(β-D -ribofuranosyl)benzotriazole ( 4a ), 5,6-dimethyl-1-(β-D -ribofuranosyl)benzotriazole ( 4b ) and 1-(β-D -ribofuranosyl)benzotriazole ( 4c ) in good yield has been accomplished by the condensation of the appropriate 1-trimethylsilylbenzotriazole ( 1a, 1b , and 1c ) with 2,3,5-tri-O-acetyl-D -ribofuranosyl bromide (2) followed by subsequent deacetylation of the reaction products. The assignment of anomeric configuration and site of glycosidation for all nucleosides reported is discussed.     

Efficient synthesis of 3‐arylaminopyrroline‐2‐ones by the tandem reaction of anilines and β,γ‐unsaturated α‐ketoesters

A concise and efficient synthetic approach to 3‐arylaminopyrroline‐2‐ones from anilines and β,γ‐unsaturated α‐ketoesters in boiling dichloromethane has been developed. This protocol possesses many advantages such as short reaction time, high isolated yields, and expanding substrate scopes. According to the isolated intermediates and controlled reactions, the reaction was tentatively proposed to involve the Michael addition/condensation and subsequent intramolecular cyclization. The structures of the title compounds were unambiguously confirmed by various spectral data such as X‐ray crystallographic analysis.     

A convenient synthesis and biological activities of novel 6‐aryl‐3‐(1,2,3,4‐tetrahydroxybutan‐1‐yl)‐7H‐1,2,4‐triazolo‐[3,4‐b][1,3,4]thiadiazines

A series of novel 6‐aryl‐3‐(1,2,3,4‐tetrahydroxybutanol‐1‐yl)‐7H‐1,2,4‐triazolo[3,4‐b][1,3,4]thiadiazines were easily synthesized in high yields by means of the reactions of 4‐amino‐5‐(1,2,3,4‐tetrahydroxybutyl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione ( 1 ) with substituted ω‐bromoacetophenones or ω‐chloroacetophenone. Nearly all of the title compounds possess plant growth‐promoting activities.