Synthesis of New 2-Aryl Substituted 2,3-Dihydroquinazoline-4(1H)-ones Under Solvent-Free Conditions,Using Molecular Iodine as a Mild and Efficient Catalyst

A simple, inexpensive, and efficient one-pot synthesis of 2,3-dihydroquinazoline-4(1H)-one derivatives under solvent-free conditions using a catalytic amount of iodine with excellent product yields is reported. This methodology provides easy, quantitative access to various 2,3-dihydroquinazoline-4(1H)-one derivatives, using commercially available iodine as a catalyst.     

One-Pot Synthesis of 3,5-Disubstituted 1,2,4-Oxadiazoles Directly from Nitrile and Hydroxylamine Hydrochloride Under Solvent-Free Conditions Using Potassium Fluoride as Catalyst and Solid Support

A one-pot synthesis of 3,5-disubstituted 1,2,4-oxadiazoles with two identical substituents directly from the reaction of nitriles and hydroxylamine hydrochloride in the presence of potassium fluoride as catalyst and solid support under solvent-free condition is described. Moreover, the formation of products has been discussed, and a plausible mechanism has been presented. Simplicity of the process, workup in aqueous media, and excellent yields are some advantages of this method.     

Imaging the In Vivo Degradation of Tissue Engineering Implants by Use of Supramolecular Radiopaque Biomaterials

For in situ tissue engineering (TE) applications it is important that implant degradation proceeds in concord with neo‐tissue formation to avoid graft failure. It will therefore be valuable to have an imaging contrast agent (CA) available that can report on the degrading implant. For this purpose, a biodegradable radiopaque biomaterial is presented, modularly composed of a bisurea chain‐extended polycaprolactone (PCL2000‐U4U) elastomer and a novel iodinated bisurea‐modified CA additive (I‐U4U). Supramolecular hydrogen bonding interactions between the components ensure their intimate mixing. Porous implant TE‐grafts are prepared by simply electrospinning a solution containing PCL2000‐U4U and I‐U4U. Rats receive an aortic interposition graft, either composed of only PCL2000‐U4U (control) or of PCL2000‐U4U and I‐U4U (test). The grafts are explanted for analysis at three time points over a 1‐month period. Computed tomography imaging of the test group implants prior to explantation shows a decrease in iodide volume and density over time. Explant analysis also indicates scaffold degradation. (Immuno)histochemistry shows comparable cellular contents and a similar neo‐tissue formation process for test and control group, demonstrating that the CA does not have apparent adverse effects. A supramolecular approach to create solid radiopaque biomaterials can therefore be used to noninvasively monitor the biodegradation of synthetic implants.     

Synthesis and in vitro antibacterial evaluation of 6-substituted 4-amino-pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidines

Pyrazolo[3,4-d]pyrimidines are one of the most important classes of fused heterocyclic compounds which exhibit a broad range of biological and medicinal properties. They are known as anticancer, antifungal, antibacterial, antiviral and anti-inflammatory agents. In this study, some new 6-substituted 4-amino-pyrazolo[3,4-d]pyrimidine derivatives were prepared via reaction of 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carbonitrile with various nitriles in the presence of sodium ethoxide as catalyst. The inhibitory properties of synthesized compounds were studied according to CLSI guidelines against some pathogenic bacteria including four gram-positive strains (Streptococcus pyogenes, Staphylococcus aureus, Bacillus cereus and Bacillus subtilis subsp. spizizenii) and three gram-negative strains (Pseudomonas aeruginosa, Shigella flexneri and Salmonella enterica subsp. enterica). The antibacterial effects of all derivatives were compared with those of antibiotics belonging to different classes. The values were reported as inhibition zone diameter (IZD), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The effect of substituents on the biological activity of derivatives was discussed as well. The inhibitory effect of compound 6a, was shown to be the most, with MIC values in the range of 32–4096 μg/mL. Since most of the synthesized compounds were effective against Streptococcus pyogenes and Pseudomonas aeruginosa, they can be considered as inhibitors of these two bacteria.     

Clean one-pot synthesis of 1,2,4-oxadiazoles under solvent-free conditions using microwave irradiation and potassium fluoride as catalyst and solid support

Potassium fluoride was found to be an efficient catalyst and solid support for the synthesis of 3,5-disubstituted-1,2,4-oxadiazoles. In this work, a one-pot method for the synthesis of these compounds from the reaction of nitriles with hydroxylamine hydrochloride and acyl chloride in the presence of potassium fluoride under solvent-free conditions using microwave irradiation has been developed. The advantages of using potassium fluoride as a solid support in comparison to conventional solid supports are simple operation and convenient separation of the products.     

An efficient one‐pot procedure for the preparation of 1,3,4‐thiadiazoles in ionic liquid [bmim]BF4 as dual solvent and catalyst

The one‐pot three component condensation of hydrazine hydrate with substituted phenylisothiocyanates followed by the addition of substituted benzaldehydes in the presence of ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([bmim]BF₄) and in the absence of any other catalyst under mild condition afforded 1,3,4‐thiadiazoles in excellent yields. The reaction workup is simple, and the ionic liquid was easily recovered from the reaction and reused. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:320–324, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20432     

Facile Synthesis of Some Novel Tetrasubstituted 2,4‐Diaminopyrimidine Derivatives in Aqueous Glucose Solution as a Fully Green Medium and Promoter

A novel environmentally benign method toward the synthesis of some novel tetrasubstituted 2,4‐diaminopyrimidine derivatives using an aqueous glucose‐mediated one‐pot three‐component reaction of malononitrile with various benzaldehyde and amidine derivatives is reported. Some pyrimidine derivatives possessing α‐amino acid moiety were synthesized by the present protocol for the first time. This protocol offers advantages including facile reaction conditions, using naturally occurring glucose as promoter and water as solvent, simple work‐up, relatively short reaction times, and high yields of the products.     

Expedient multicomponent synthesis of a small library of some novel highly substituted pyrido[2,3-d]pyrimidine derivatives mediated and promoted by deep eutectic solvent and in vitro and quantum mechanical study of their antibacterial and antifungal activities

Molecular Diversity - A facile and efficient catalyst- and oxidant-free multicomponent synthesis of a small library of highly substituted pyrido[2,3-d]pyrimidine derivatives is reported. The...     

Regioselective Photoelectrocyclization of (E/E)-Arylidene-β-ionones; Synthesis of Some 1,7,7-trimethyl-3-(e-2′-arylethenyl)-2-oxabicyclo [4.4.0] Deca-3,5-dienes

Facile synthesis of a number of 1,7,7-trimethyl -3-(E-2′-arylethenyl)-2-oxabicyclo [4.4.0] deca-3, 5-dienes, through UV irradiation of (E/E) -arylidene-β-ionones, is described.