Synthesis of Spiro Dihydrofurans and 1,8-Dioxo-xanthenes via DABCO Catalyzed Tandem Reaction of Aldehyde with Cyclohexane-1,3-dione and Dimedone

The 1,4-diazabicyclo[2.2.2]octane（DABCO） catalyzed reaction of cyclohexane-1,3-dione or dimedone with various aldehydes in acetonitrile resulted in the polysubstituted tetraketones, spiro dihydrofurans or 1,8-dioxo-xanthenes derivatives as main products respectively according to the structure of reactants and reaction conditions.

Synthesis of Antipyrine Derivatives Derived from Dimedone

Coupling of dimedone with the diazonium salt of 4-aminoantipyrine afforded 2,3-dimethyl-4-[2-（5,5-dimethyl- 2,6-dioxocyclohex-2-ylidend）-hydrazino]-5-oxo-1-phenylpyrazoline （3）. Reaction of 3 with excess phenylhydrazine gave the mixed trishydrazone derivative 4. Treatment of 3 with hydroxylamine produced the bisoxime 5 which upon dehydrative cyclization with acetic anhydride gave the corrsponding tetrahydrobenzo[d][1,2,3]triazole derivative 7. A one-pot synthesis of 7 was done by reacting 3 with hydroxylamine hydrochloride in pyridine, followed by heatment with acetic anhydride.

An efficient synthesis of 2,2′-arylmethylene bis-(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) and 1,8-dioxooctahydroxanthenes using ZnO and ZnO-acetyl chloride

2,2'-Arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) 4l-s produced from reaction between dimedone with various aldehydes in acetonitrile using ZnO as a catalyst;whereas in the presence of ZnO-acetyl chloride catalysts the reaction is limited to give only 1,8-dioxo-octahydroxanthenes 3a-k in very good yields.

A Green Protocol for Efficient Synthesis of 1,8-Dioxo-Octahydroxanthenes Using Ionic Liquid

A clean, simple, efficient synthesis of 1,8-dioxo-octahydroxanthenes derivatives using ionic liquid 1-butyl, 3-me- thylimidazolium perchlorate ([bmim] ClO4) has been developed. The method provides several advantages such as simple work up, environmental friendliness and excellent yields in short reaction time. The ionic liquid [bmim] ClO4 used was recovered and reused for three times.

Synthesis of 2,2'-arylmethylene bis(3-hydroxy-5,5-dimethyl-2-cyclohexene-1-one) in aqueous medium at room temperature

The reaction of dimedone with various aromatic aldehydes produces 2,2＇-arylmethylene bis （3-hydroxy-5,5-dimethyl-2- cyclohexene-l-one） in excellent yields. The reactions occur in water as solvent at room temperature and avoiding the addition of any catalyst. The workup procedure is very simple and the products do not required further purification.

Palladium (0) Nanoparticles: A Novel and Reusable Catalyst for the Synthesis of Various Pyran Derivatives

A ligand free, Palladium nanoparticles catalyzed synthesis of pyran derivatives using C-H activated compound, malononitrile and aryl aldehyde via Knoevenagel condensation followed by Michael addition reaction using Palladium nanoparticles as catalyst in one-pot is described herein. The advantages of this method lie in its simplicity, low catalyst loading, cost effectiveness and easy to handle. The Palladium Nanoparticles can be reused without loss of activity even after recycling four times. The palladium nanoparticles were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM). The present method also allows us to synthesize highly functionalized title compounds from simple and readily available inputs.

Microwave-prompted Reaction of Cinnamonitrile Derivatives with 5,5-Dimethyl-1,3-cyclohexanedione

In the reactions of α-cyanocinnamonitrile or β-cyano-β-carbo-thoxy styrenewith 5,5-dimethyl-1,3-cyclohexanedione in the presence of ammonium acetate under microwaveirradiation without solvent, the2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-7,7-dimethyl-4H-benzo-[b]-pyran derivatives were obtained.However, in the reactions of arylidenecyanoacetamide with 5,5-dimethyl-1,3-cyclohexanedione underthe same reaction conditions, the acridine derivatives were obtained. The structures of the productswere determined by single crystal X-ray diffraction analysis.

One-pot Synthesis of lO-Methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-l,8-dione Derivatives under Microwave Heating without Catalyst

A series of 10-methyl-1,2,3,4,5,6,7,8,9,10-decahydroacridine-1,8-dione derivatives were synthesized by one-pot reaction of aldehyde, dimedone or 1,3-cyclohexanedione and methylamine in glycol or water under microwave heating without catalyst. The method has the advantage of short routine and reaction time, high yields as well as friendly environment. And the reaction was not only suitable for aliphatic and aromatic monoaldehyde, but also for aromatic dialdehyde.

Multicomponent synthesis of dihydropyridines catalyzed by L-proline

Multicomponent synthesis of mono and bis 4-substituted-1,4-dihydropyridines from aldehydes,dimedone and ammonium acetate in the presence of an efficient recyclable catalyst,L-proline,in high yield and short reaction time is 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.