Synthesis and Suzuki-Miyaura reactions of 5-halo-3,4-dihydropyrimidin-2(1H)-ones

A novel synthesis of 6-methyl-4-phenyl-5-substituted-3,4-dihydropyrimidin-2(1H)-ones from 6-methyl-4-phenyl-5-halo-3,4-dihydropyrimidin-2(1H)-ones via the Suzuki-Miyaura reaction is reported. These previously unknown heterocyclic halides are easily prepared using the Biginelli multicomponent reaction followed by halodecarboxylation. The effect of varied substitution at the C-4 position on the cross-coupling reaction is also examined.     

An efficient synthesis of β-ketoesters via transesterification and its application in Biginelli reaction under solvent-free,catalyst-free conditions

A simple and efficient transesterification process for the synthesis of β-ketoester derivatives has been achieved by the reaction of methyl β-ketoester with higher alcohols at 110 °C under solvent-free, catalyst-free conditions and its application in synthesis of 3,4-dihydropyrimidin-2(1H)-ones C-5 ester derivatives via Biginelli reaction has been described.     

5-aroyl-3,4-dihydropyrimidin-2-one library generation via automated sequential and parallel microwave-assisted synthesis techniques

An efficient two-step synthetic pathway toward the preparation of diversely substituted 5-aroyl-3,4-dihydropyrimidin-2-ones is realized. The protocol involves an initial trimethylsilyl chloride-mediated Biginelli multicomponent reaction involving S-ethyl acetothioacetate, aromatic aldehydes, and ureas as building blocks to generate a set of 3,4-dihydropyrimidine-5-carboxylic acid thiol esters. These thiol esters serve as starting materials for a subsequent Pd-catalyzed Cu-mediated Liebeskind-Srogl cross-coupling reaction with boronic acids to provide the desired 5-aroyl-3,4-dihydropyrimidin-2-one derivatives. Both steps were performed using microwave heating in sealed vessels, either in an automated sequential or parallel format using dedicated microwave reactor instrumentation. A diverse library of 30 5-aroyl-3,4-dihydropyrimidin-2-ones was prepared with commercially available aldehyde, urea, and boronic acid building blocks as starting materials.     

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.     

An efficient, high yield protocol for the one-pot synthesis of dihydropyrimidin-2(1H)-ones catalyzed by iodine

The use of iodine, as a catalyst for the one-pot synthesis of 3,4-dihydropyrimidin-2(1H)-ones is reported.     

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by thiamine hydrochloride in water under ultrasound irradiation

An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using thiamine hydrochloride as a catalyst has been achieved. These ultrasound-assisted reactions proceed efficiently in water in the absence of organic solvent. Utilization of ultrasound irradiation, simple reaction conditions, isolation, and purification makes this manipulation very interesting from an economic and environmental perspective.     

Biginelli reaction in aqueous medium: a greener and sustainable approach to substituted 3,4-dihydropyrimidin-2(1H)-ones

An environmentally benign aqueous Biginelli protocol for the synthesis of substituted 3,4-dihydropyrimidin-2(1H)-ones using polystyrenesulfonic acid (PSSA) as a catalyst has been achieved. These microwave-assisted reactions proceed efficiently in water in the absence of organic solvent, with simple filtration as the product isolation step.     

Novel Biginelli-like three-component cyclocondensation reaction: efficient synthesis of 5-unsubstituted 3,4-dihydropyrimidin-2(1H)-ones

Iron (III) catalyzed the three-component Biginelli-like cyclocondensation reaction efficiently in acetonitrile to afford the corresponding 5-unsubstituted 3,4-dihydropyrimidin-2-(1H)-ones in high yields. The first Biginelli-like reactions of urea, aldehydes and ketones were furnished important new 3,4-dihydropyrimidin-2-(1H)-ones derivatives suitable for further study.     

Ionic liquid phase technology supported the three component synthesis of Hantzsch 1,4-dihydropyridines and Biginelli 3,4-dihydropyrimidin-2(1H)-ones under microwave dielectric heating

A microwave dielectric heating assisted liquid phase synthesis of 1,4-dihydropyridines, 3,4-dihydropyrimidin-2(1H)-ones, pyridines and polyhydroquinolines using task-specific ionic liquid as a soluble support was described. The efficiency of the ionic liquid phase organic synthesis (IoLiPOS) methodology was demonstrated by using a one-pot three component condensation. The structure of the intermediates in each step was verified routinely by spectroscopic analysis and, after cleavage the target compounds were obtained in good yields and high purities.     

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.     

An efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones catalyzed by molten [Et3NH][HSO4]

A simple ammonium salt of sulfuric acid in molten state was used as a cheap and mild acidic ionic liquid for efficient synthesis of 3,4-dihydropyrimidin-2(1H)-ones in good to excellent yields.     

An Efficient Synthesis of New 3,4-Dihydropyrimidin- 2(1H)-ones Incorporating a Phenyl Moiety at C-5 and C-6 Catalyzed by TMSCl and Co(OAc)2.4H2O

New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) ₂ .4H ₂ O as an efficient Lewis acid catalyst.     

Biginelli reaction starting directly from alcohols

An efficient of one-pot oxidative access to 3,4-dihydropyrimidin-2-(1H)-ones directly from aromatic alcohols under mild conditions is reported. The protocol involves 1-methylimidazolium hydrogen sulphate [Hmim]HSO₄ catalyzed oxidation of aromatic alcohols to aromatic aldehydes with NaNO₃ followed by their cyclocondensation with 1,3-dicarbonyl compounds and urea in the same reaction vessel at 80 °C within 2-4 h to afford 3,4-dihydropyrimidin-2-(1H)-ones in 55-97% overall yields. Thus, the present work utilizing alcohols instead of aldehyde in Biginelli reaction is a valid and green alternative to the classical synthesis of 3,4-dihydropyrimidin-2-(1H)-ones.     

Efficient,Green, Solvent-Free Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones via Biginelli Reaction Catalyzed by Cu(NO3)2·3H2O

The synthesis of 3,4-dihydropyrimidin-2-(1H)-ones derivatives via a three-component Biginelli reaction using copper nitrate as a catalyst under solventless conditions is reported, providing a green, rapid, efficient, and convenient method for the preparation of Biginelli compounds in good yields.     

Xanthan Sulfuric Acid: A New and Efficient Biosupported Solid Acid Catalyst for the Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones

Xanthan sulfuric acid (XSA) is employed as a recyclable catalyst for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones. These syntheses were performed via a one-pot, three-component condensation of aldehydes, amines, and urea/thiourea under solvent-free conditions.     

Borax: An Ecofriendly and Efficient Catalyst for One-Pot Synthesis of 3,4-Dihydropyrimidine-2(1H)-ones under Solvent-Free Conditions

Borax in the presence of a very small amount of 5 M sulfuric acid efficiently catalyses the three-component condensation of an aldehyde, β-ketoester, and urea or thiourea to afford the corresponding 3,4-dihydropyrimidin-2(1H)-ones or 3,4-dihydropyrimidin-2(1H)-thiones in good to excellent yields under solvent-free conditions at 80 °C. Compared with the classical Biginelli reaction conditions, this new method has the advantage of excellent yield, short reaction time (1–2 h), easy workup, and no use of volatile organic solvent.     

Propane phosphonic acid anhydride: a new promoter for the one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Propane phosphonic acid anhydride has been found to promote the Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones. The use of this agent is characterized by moderate costs, low toxicity and simple workup conditions.     

Synthesis of pyrazolo[3,4-d]-4,5-dihydropyrimidin-6-ones

A small library of hitherto unprepared pyrazolo[3,4-d]-4,5-dihydropyrimidin-6-ones was synthesized on a preparative scale. The synthesis starts with a substituted 5-aminopyrazole that reacts with an isocyanate to give the corresponding urea. The latter undergoes a chlorotrimethylsilane-promoted [5+1] cyclocondensation with an aldehyde yielding the title pyrazolo[3,4-d]-4,5-dihydropyrimidin-6-one. Both synthetic steps are high-yielding (74–94%). The intermediates and the target compounds were isolated by simple crystallization. Ketones with the exception of isatin do not react with the open-chain urea intermediates.     

A simple and efficient synthesis of 3,4-dihydropyrimidin-2-(1H)-ones via Biginelli reaction catalyzed by nanomagnetic-supported sulfonic acid

Nanomagnetic-supported sulfonic acid is found to be a new, powerful, and reusable heterogeneous catalyst for the rapid synthesis of 3,4-dihydropyrimidin-2-(1H)-ones under conventional heating and microwave irradiation. This is the first example of combination of magnetic iron nanoparticles and microwave technique for the multicomponent reaction. The optical behaviors of the 3,4-dihydropyrimidin-2-(1H)-ones have been investigated by UV–vis spectroscopy.     

Optically active 4-amino-4-aryl-5,5,5-trifluoropentan-2-ones: Versatile reagents for synthesis of chiral 4-trifluoromethyl-3,4-dihydroazin-2-ones

A cyclocondensation of disubstituted (thio)ureas and isocyanates derived from enantiomerically enriched 4-amino-4-aryl-5,5,5-trifluoropentan-2-ones affords a novel synthetic access to chiral 4-trifluoromethyl-substituted 3,4-dihydropyrimidin-2(1H)-(thi)ones and 3,4-dihydro-1,3-oxazin-2-ones, respectively.