Knoevenagel condensation of α,β-unsaturated aromatic aldehydes with barbituric acid under non-catalytic and solvent-free conditions

An efficient route for the synthesis of 5-（arylpropenylidine）-2,4,6-pyrimidinetrione 3 from an appropriate α,βunsaturated aromatic aldehydes 1 and barbituric acid 2 under both non-catalytic and solvent-free microwave irradiation conditions was described. In this way, a range of biologically important compounds 3 was obtained in good to excellent yields （86-98%） in a very short reaction time （30-80 s）.

Effect of Frontier Orbital on Aggregation Behavior of Barbituric Acid Derivatives

Two amphiphilic barbituric acid derivatives with a D-π-A structure, 5-(4-dodecyloxybenzylidene)-(1H,3H)-2,4,6-pyrimidinetrione(PB_ 12) and 5-(4-N,N-didodecylaminobenzylidene)-(1H,3H)-2,4,6-pyrimidintrione(AB_ 12) were found to show different aggregation behavior in chloroform. PB_ 12, a derivative with weak electron donating and strong electron drawing substituents, tends to aggregate in a head-to-tail manner, whereas AB_ 12, a derivative with both strong electron donating and drawing substituents, tends to aggregate in a face-to-face manner at a higher concentration. The cyclic voltammograms of AB_ 12 and PB_ 12 show that their energy levels of LUMO approach each other, however, the energy level of HOMO of AB_ 12 is much higher than that of PB_ 12.

Molecular diversity of triphenylphosphine promoted reaction of electron-deficient alkynes and arylidene Meldrum acid(N,N’-dimethylbarbituric acid)

The three-component reaction of triphenylphosphine,dimethyl hex-2-en-4-ynedioate and arylidene N,N’-dimethylbarbituric acids in dry methylene dichloride at room temperature afforded trans-1,3-disubstituted 7,9-diazaspiro[4.5]dec-1-enes in good yields and with high diastereoselectivity.However,the similar three-component reaction with arylidene Meldrum acids resulted in a mixtures of cis/trans-1,2-disubstituted 7,9-dioxaspiro[4.5]dec-1-enes.Additionally,the three-component reaction of triphenylphosphine,dimethyl but-2-ynedioate and arylidene Meldrum acids gave polysubstituted 5-(triphe nyl-λ~5-phosphanylidene)cyclopenta-1,3-die nes.A plausible reaction mechanism was proposed for the formation of various products with different regioselectivity and diastereoselectivity.

One-pot synthesis of 7-aryl-11,12-dihydrobenzo[h]pyrimido-[4,5-b]quinoline-8,10(7H,9H)-diones via three-component reaction in ionic liquid

A series of new 7-aryl-11,12-dihydrobenzo[h]pyrimido-[4,5-b]quinoline-8,10（7H,9H）-diones were synthesized via three-component reaction of aldehydes,l-naphthylamine and barbituric acid in ionic liquid.The method provided several advantages such as easy work-up,high yields and environmentally benign procedure.

Molecular Component Structures MediatedFormation of Self-assemblies

Molecular recognition directed self-assemblies from complementary molecular components, melamine and barbituric acid derivatives were studied by means of NMR, fluorescence, and TEM. It was found that both the process of the self-assembly and the morphologies of the result- ed self-assemblies could be mediated by modifying the structures of the molecular components used. The effect of the structures of the molecular components on the formation of the self-as- semblies was discussed in terms of intermolecular interactions.

Novel Synthesis of Barbiturates

Knovenagel reaction of barbituric acid with different aldehydes were used to synthesize new barbiturates. This is a novel method which can be used to synthsis various types of new generation of barbiturates which are different from the previously reported.

Alum （KAI（SO4）2·12H2O） Catalyzed Multicomponent Transformation： Simple, Efficient, and Green Route to Synthesis of Functional- ized Spiro[chromeno[2,3-d]pyrimidine-5,3＇-indoline]-tetraones in Ionic Liquid Media

The combination of isatin, barbituric acid, and cyclohexane-1,3-dione derivatives in the presence of alum （KAI（SO4）2· 12H2O） as a catalyst for 15 min was found to be a suitable and efficient method for the synthesis of spiro[chromeno[2,3-d]pyrimidine-5,3＇-indoline]-tetraones.

Recognition-improved monolayer formation on air-water interface

Molecular recognition mechanism was introduced into the monolayer formation of two barbituric derivatives, B1 and B2, on a series of melamine derivatives containing water subphase. The recognition pattern was found that each barbituric(or melamine) group forms 9-fold H-bonds on its two edges, respectively, with two of its neighboring melamine(barbituric) cores in the ratio of 1:1 on air-water interface. The area per molecule in this pattern is about 60-65 Angstrom(2) for both B1 and B2. Such recognition improves the monolayer formation of B1 by increasing the collapse pressure around 20 mN/M and modulates the intermolecular distance of B2 in monolayer. These effects should be quite meaningful for both theoretical research and practical application of Langmuir-Blodgett films, especially.

Improved microwave-assisted catalyst-free synthesis of9-aryl-5,9-dihydropyrimido[4,5-d][1,2,4]triazolo[1,5-a]pyrimidine-6,8(4H,7H)-dione derivatives

Agreen regioselective synthesis of some new and known 9-aryl-5,9-dihydropyrimido[4,5-d][l,2,4]triazolo[1,5-a]pyrimidine-6,8（4H,7H）-diones has been described via the microwave-assisted one-pot reaction of 3-amino-1H-1,2,4-triazoles,aromatic aldehydes and barbituric acids under solvent- and catalyst-free conditions.This operationally simple procedure is less laborious and provides a better scope than previously reported procedures.