Aryliodoazide Synthons: A Different Approach for Diversified Synthesis of 2-Aminothiazole, 1,3-Thiazole, and 1,3-Selenazole Scaffolds.

Several straightforward and practical processes have been established for the construction of 2-aminothiazoles, 1,3-thiazoles and 1,3-selenazoles from aryliodoazides. These strategies successfully proceed with a wide spectrum of substituted thioamides and its derivatives producing the resulting five-membered heterocycles obtained in satisfactory yields. The unique features of these protocols are operational simplicity and highly functional group tolerance, which make them convenient and practical routes for the preparation of various libraries of 2-aminothiazoles, 1,3-thiazoles, and 1,3-selenazoles.

CsF-Catalyzed Transannulation Reaction of Oxazolones: Diastereoselective Synthesis of Diversified trans- N-(6-Oxo-1,4,5,6-tetrahydropyrimidin-5-yl)benzamides with Arylidene Azlactones and Amidines.

A versatile and straightforward synthetic strategy for the construction of new tetrasubstituted 1,3-diazinones is described. The procedure is based on CsF-catalyzed, microwave-assisted, ring transformation reaction of arylidene azlactones with amidines. Moreover, this technique provides diversified trans- N-(6-oxo-1,4,5,6-tetrahydropyrimidin-5-yl)benzamides with a good antimicrobial activity.

Novel Multicomponent Synthesis of Pyridine-Pyrimidines and Their Bis-Derivatives Catalyzed by Triazine Diphosphonium Hydrogen Sulfate Ionic Liquid Supported on Functionalized Nanosilica.

In this Research Article, we report an efficient synthesis of 1,3-dimethyl-5-aryl-7-(pyridine-3(2)(4)-yl)pyrimidine-2,4(1H,3H)-diones via a three-component reaction of aryl aldehydes, 1,3-dimethyl-6-aminouracil and carbonitriles in the presences of triazine diphosphonium hydrogen sulfate ionic liquid supported on functionalized nanosilica (APTADPHS-nSiO2) as a reusable catalyst under microwave irradiation and solvent-free conditions. The bis-derivatives of pyridine-pyrimidines were also efficiently prepared from dialdehydes and dinitriles. In addition, 3-methyl-1H-pyrazole-5-amine was used successfully instead of 1,3-dimethyl-6-aminouracil under the same conditions to afford the corresponding products in high yields. The catalyst can be reused at least five times without any significant loss of its activity. The easy recovery, reusability and excellent activity of the catalyst as well as easy workup are other noteworthy advantages of this method.

Green and Facile Synthesis of Highly Photoluminescent Multicolor Carbon Nanocrystals for Cancer Therapy and Imaging.

Carbon dots (CDs), as a new generation of fluorescent nanoparticles, have been greatly considered for different biomedical applications. In the present study, a one-pot hydrothermal method was developed for the synthesis of a series of carbon dots (CDs) for cancer imaging and therapy. Taxane diterpenoids were utilized as the carbon source, different diamines were used as the nitrogen source, and folic acid was used as a targeting agent. High-quality photostable and multicolor (blue and green) carbon nanocrystals with a hexagonal shape, a narrow size distribution of less than 20 nm, and high fluorescence quantum yield of up to 50.4% were obtained from taxanes in combination with m-phenylenediamine and folic acid to give the best results. The nanoparticles displayed a potent anticancer activity with IC50 values of 31.3 ± 2.7 and 34.1 ± 1.1 µg mL-1 for the human MCF-7 and HeLa cancer cell lines, respectively, and IC50 value of 120.5 ± 3.8 µg mL-1 on the normal human fibroblast cells. The flow cytometry studies determined apoptosis-mediated cell death as the main anticancer mechanism of CDs, and the molecular studies revealed the induction of both extrinsic and intrinsic apoptosis pathways. The overall results indicated the great potential of synthesized CDs for the simultaneous cancer imaging and therapy.

New pyridinium-based ionic liquid as an excellent solvent-catalyst system for the one-pot three-component synthesis of 2,3-disubstituted quinolines.

The synthesis of a variety of 2,3-disubstituted quinolines has been achieved successfully via a one-pot three-component reaction of arylamines, arylaldehydes and aliphatic aldehydes in the presence of butylpyridinium tetrachloroindate(III), [bpy][InCl4], ionic liquid as a green catalyst and solvent. Mild conditions with excellent conversions, and simple product isolation procedure are noteworthy advantages of this method. The recyclability of the ionic liquid makes this protocol environmentally benign.

One-pot three-component synthesis of pyrano [3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones.

An efficient one-pot synthesis of novel pyrano[3,2-b]pyrazolo[4,3-e]pyridin-8(1H)-ones via three-component condensation of kojic acid, 1-H-pyrazol-5-amines and aldehydes in the presence of a catalytic amount of Zn(OTf)(2) followed by H(2)O(2)-mediated oxidation is reported. Furthermore, the synthesis of 1'H-spiro[indoline-3,4'-pyrano[2,3-b]pyrazolo[3,4-e]pyridine]-2,8'(9'H)-diones were chosen for the library validation.

Synthesis of trans-1,3-diaryl-2-(5-methylisoxazol-3-yl)-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines via bismuth(III)-catalyzed one-pot pseudo-four component reaction.

An expeditious, straightforward and efficient synthesis of diversely naphtho[1,2-e][1,3]oxazines via one-pot condensation reaction of ß- naphthol, 3-amino-5-methylisoxazole and arylaldehydes catalyzed by bismuth(III) trifluoromethanesulfonate is described. The reaction preferentially afforded 1,3-trans oxazines.

Regioselective multi-component synthesis of 1H-pyrazolo[3,4-d]pyrimidine-6(7H)-thiones.

A variety of pyrazolo[3,4-d]pyrimidine-6(7H)-thione derivatives were easily synthesized with a novel, simple, efficient, and regioselective method via three-component condensation reaction of 5-methyl-1H-pyrazol-3-amine, arylisothiocyanates, and aldehydes in the presence of catalytic amount of p-toluenesulfonic acid (p-TSA) in 1-butyl-3-methylimidazolium bromide ionic liquid with excellent yields and short reaction times.

Thermal stability and enzymatic activity of RNase A in the presence of cationic gemini surfactants.

The thermal stability and enzymatic activity of bovine pancreatic ribonuclease A (RNase A) have been investigated in the presence of a homologous series of cationic gemini surfactants (alkanediyl-α,ω-bis(hydroxyethyl methyl hexadecyl ammonium bromide)). UV, circular dichorism and fluorescence spectroscopies have been used for this study. The denaturation curves at various surfactant concentrations were analyzed on basis of a two-transition model to obtain values of T(m) (temperature at the midpoint of denaturation) and ΔH(m) (enthalpy change at T(m)) of each transition. The main conclusion of this study is that these cationic gemini surfactants slightly activate and stabilize RNase A below their critical micelle concentrations at pH 5.0. The cationic gemini surfactant with the shorter spacer interacts more efficiently with RNase A than those with longer spacers.

Interactions of gemini surfactants with two model proteins: NMR, CD, and fluorescence spectroscopies.

Gemini surfactants have two polar head groups and two hydrocarbon tails. Compared with conventional surfactants, geminis have much lower (µM vs. mM) critical micelle concentrations and possess slower (ms vs. µs) monomer <-- / --> micelle kinetics. The structure of the gemini surfactants studied is [HOCH(2)CH(2)-, CH(3)-, CH(3)(CH(2))(15)-N(+)-(CH(2))(s)-N(+)-(CH(2))(15)CH(3),-CH(3),-CH(2)CH(2)OH]·2Br(-) where s=4, 5, or 6. Our objective is to reveal the effect of these cationic gemini surfactants on the structure and stability of two model proteins: Ribonuclease A (RNase A) and Hen Egg White Lysozyme (HEWL). 2D (1)H NMR and Circular Dichroism (CD) spectroscopies show that the conformation of RNase A and HEWL is unaffected at low to neutral pH where these proteins are positively charged, although hydrogen exchange shows that RNase A's conformational stability is slightly lowered. At alkaline pH, where these proteins lose their net positive charge, fluorescence and CD spectroscopies and ITC experiments show that they do interact with gemini surfactants, and multiple protein•gemini complexes are observed. Based on the results, we conclude that these cationic gemini surfactants neither interact strongly with nor severely destabilize these well folded proteins in physiological conditions, and we advance that they can serve as useful membrane mimetics for studying the interactions between membrane components and positively charged proteins.

Ultrasound-promoted a green protocol for the synthesis of 2,4-diarylthiazoles under ambient temperature in [bmim]BF(4).

A mild, efficient, facile and eco-friendly procedure for the synthesis of 2,4-diarylthiazoles from arylthioamides and alpha-bromoacetophenones in 1-n-butyl-3-methylimidazolium tetrafluoroborate as a "green" media under ultrasound irradiation at room temperature is described. It is interesting to mention that only one product was obtained when two different alpha-bromoacetophenones were reacted with 1,3-phenyl dithioamide as the substrate. Work-up is very simple and there is no need to purify the product. A recycling study confirmed that the ionic liquid can be reused multiple times without a significant loss in its activity.