Synthesis of fused uracils: pyrano[2,3-d]pyrimidines and 1,4-bis(pyrano[2,3-d]pyrimidinyl)benzenes by domino Knoevenagel/Diels-Alder reactions
نویسنده
چکیده
ABSTRACT Knoevenagel condensation of barbituric acids with aromatic aldehydes containing one or two formyl groups was carried out. 5-Arylidenebarbituric acids underwent smooth hetero-Diels-Alder (HDA) reactions with enol ethers to afford cis and trans diastereoisomers of pyrano[2,3-d]pyrimidine-2,4-diones and 5,5'-(1,4-phenylene)bis[2H-pyrano[2,3-d]pyrimidine-2,4(3H)-dione] derivatives in excellent yields (75-88 %). Syntheses were realized by Knoevenagel condensation and HDA reaction in four different reaction conditions: Knoevenagel condensation in water and Diels-Alder reaction in methylene chloride solution, Knoevenagel condensation in water and Diels-Alder reaction without solvent, three-component one-pot reaction in methylene chloride solution, or three-component one-pot reaction in water. All reactions were carried out without catalyst at room temperature. The reactions of malononitrile with Knoevenagel condensation products of barbituric acids and heteroaromatic aldehydes or terephthalaldehyde were examined and did not provide corresponding pyranopyrimidines. GRAPHICAL ABSTRACT .
منابع مشابه
An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium-catalyzed multi-component domino reaction
Various novel pyrano [2,3-d]pyrimidines 5 and furopyrano [2,3-d]pyrimidines 7 were synthesized in 80-99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III) chloride. The reaction also proceeds in aqueous media without using any catalyst, b...
متن کاملApplication of nano TiO2@KSF as an efficient and reusable catalyst for the synthesis of pyrano-pyrimidines
In this work, Nano TiO2@KSF used as an efficient, homogeneous and reusable catalyst for the synthesis of pyrano[2,3-d]-pyrimidinone derivatives via three-component reactions between malononitrile, barbituric acid and various aldehydes in water. The products were formed in high yields within short reaction times. Also, this catalyst can be reused several times without loss of its catalytic activ...
متن کاملOne-pot Synthesis of Pyrano[2,3-d]Pyrimidines using Nanocellulose-SbCl5 as a Highly Efficient and Bio-based Catalyst
The reaction of nano-cellulose and antimony pentachloridein dichloromethane gave nano-cellulose-SbCl5. Also nano-cellulose-SbCl5 has beencharacterized by energy dispersive X-ray spectroscopy(EDX), scanning electron microscopy (SEM)and Fourier transform infrared spectroscopy(FTIR).Nano-cellulose-SbCl5has been applied as a nano-catalyst for synthesis of pyrano[2,3-d]pyrimidines from the simple on...
متن کاملA Clean and Highly Efficient Synthesis of Oxindole Substituted Pyrrolo[2,3-d]Pyrimidines under Ultrasound Irradiation
A practical and new method for the synthesis oxindole substituted pyrrolo[2,3-d]pyrimidines by the condensation of isatin, acetophenone and 6-amino-uracil under ultrasound irradiation conditions at 60 °C was described. The reaction was developed via a sequential tandem process to afford the oxindole substituted pyrrolo[2,3-d]pyrimidines in good to excellent yields. All reactions performed effic...
متن کاملTetra-N-Butyl ammonium hydroxide mediated one-pot synthesis of pyrano [2, 3-d] pyrimidinone Derivatives
Tetra-N-Butyl Ammonium Hydroxide was used as a catalyst for one-pot, three component condensation reactions consisting of aromatic aldehydes, malononitrile and barbituric acid in ethanol:water solvent system at 60oC. Current method has major advantages like mild reaction conditions with simple operation, high yields, by using a less toxic and lower costlier catalyst.In conclusion, we have explo...
متن کامل