Chitosan-silica Sulfate Nano Hybrid: An Efficient Biopolymer Based-heterogeneous Nano Catalyst for Solvent-free Synthesis of 3,4-Dihydropyrimidine-2(1H)-one/thiones

A green and highly efficient approach for the synthesis of 3,4-dihydropyrimidine-2(1H)-one/thione derivatives is described. In this approach, the three-component Biginelli reaction between (thio)urea, methyl acetoacetate and aldehydes under solvent-free condition in the presence of chitosan-silica sulfate nano hybrid (CSSNH) as a green and heterogeneous nano catalyst affords the corresponding products in good to excellent yields and in short reaction times. CSSNH is a cheap, eco-friendly, and non-toxic nano catalyst that could be easily prepared, handled, and reused for many reaction runs without significant loss of its activity.

Mo@GAA-Fe3O4 MNPs: a highly efficient and environmentally friendly heterogeneous magnetic nanocatalyst for the synthesis of polyhydroquinoline derivatives

Polyhydroquinolines were obtained from a sequential four-component reaction between dimedone or 1,3-cyclohexandione, ethyl acetoacetate, or methyl acetoacetate as a β-ketoester, aldehydes, and ammonium acetate, with Mo@GAA-Fe3O4 MNPs as a green nanocatalyst.

Three-Component Efficient Synthesis of 2-Amino-3-cyano-4H-pyrans Catalyzed by Diammonium hydrogen phosphate in Aqueous Media

Background: The present method is facile, green and effective for the synthesis of 2-amino-3-cyano-4H-pyran derivatives which are obtained by one-pot three-component condensation reactions of aromatic aldehydes, malononitrile and methyl acetoacetate using diammonium hydrogen phosphate (DAHP) in aqueous ethanol at room temperature. Methods: 2-Amino-3-cyano-4H-pyrans were synthesized through a one-pot three-component tandem Knoevenagel cyclocondensation reaction of aromatic aldehydes, malononitrile, and methyl acetoacetate in the presence of 10 mol% of DAHP as a catalyst under aqueous ethanol medium at room temperature. All obtained structures were confirmed by their physical constant, IR, 1H NMR, 13C NMR spectroscopy, also elemental analyses for new derivatives. Results: Three-component synthesis of 2-amino-3-cyano-4H-pyrans catalyzed by DAHP with aromatic aldehydes, malononitrile and methyl acetoacetate in aqueous ethanol medium at room temperature was prepared. The achieved derivatives (nine entries) were well synthesized in excellent yields. Conclusion: The present method is straightforward, quick, and most efficient green protocol for the synthesis of 2-amino3-cyano-4H-pyran derivatives using highly inexpensive, easily handle and, nontoxic DAHP as an efficient catalyst in aqueous ethanol medium at room temperature.

Triethanolammonium Acetate ([TEAH][OAc]) as a Recyclable Promoter and Medium for Green and Four-component Synthesis of Polyfunctionalized Pyrrole Derivatives

: Multi-component synthesis of functionalized pyrrole derivatives was achieved via four-component condensation reaction of ethyl acetoacetate/ methyl acetoacetate, aromatic amines, nitromethane, and aromatic aldehydes using triethanolammonium acetate ([TEAH] [OAc]) ionic liquid as a green solvent and catalyst. The easy access to highly substituted pyrroles, easy reusability of the catalyst, broad substrate scopes, straightforward, no column chromatography, short reaction time, good yields of products and solvent-free conditions make this protocol environmentally friendly and practically attractive.

Advanced Catalyst-Free Pseudo-Six-Component Synthesis of Tetrahydrodipyrazolopyridines in Water by Using Ammonium Carbonate as an Ecofriendly Source of Nitrogen

This work describes an improved environmentally friendly method for the synthesis of tetrahydrodipyrazolopyridines (THDPPs) in water through a catalyst-free pseudo-six-component reaction of alkyl acetoacetates, hydrazine hydrate, and ammonium carbonate with an aldehyde in a mole ratio of 2:2:1:1 at room temperature. The ammonium carbonate serves as a green source of nitrogen for the central 1,4-dihydropyridine ring in the THDPPs. Methyl acetoacetate reacts faster than either ethyl or propyl acetoacetate in this method. The product precipitates during the reaction and is simply collected by filtration. Advantages of this environmentally benign method include no use of an organic solvent, no hazardous waste, rapid clean reactions, and excellent yields of products.

Orthoamide und Iminiumsalze, IIIC. Weitere Ergebnisse bei der Umsetzung von Orthoamiden der Alkincarbonsäuren mit CH2- und CH2/NH-aciden Verbindungen

The 1,1-bis(dimethylamino)-1,3-butadienes (keten aminals) 11a–l are prepared from orthoamide derivatives of alkyne carbonxylic acids 9b, d, e, i and CH2-acidic compounds 10a–c, f–h, k, o. The C-silylated orthoamide derivative 9c shows an ambivalent behaviour towards CH-acidic compounds. Reactions of 9c with strong CH2-acidic compounds like the nitro alkanes 10m, n and strongly enolized carbonyl compounds as methyl acetoacetate, cyanoacetamide, dibenzoylmethane, 1,3-dimethylbarbituric acid proceed under desilylation to give the ketene aminals 11u–z. In contrast to these reactions, the C-silylated ketene aminals 11o–t are obtained from 9c and weaker CH2-acidic compounds as dimethyl malonate, cyanoacetic acid derivatives and benzylcyanides. CH2/NH2-acidic compounds [cyanoacetamide (10d) and N-ethyl-cyanoacetamide (10f)] react with the orthoamide derivatives 9b, e–g at the acidic carbon-hydrogen bond to give the ketene aminals 11ac, ad, af, ag, ai, which cyclize to the pyridones 14a–d, d–g on heating. From the reaction of the orthoamide 9d with cyanoacetamide the pyridone 14c results directly. The persubstituted pyridone derivative 19 is formed by the reaction of cyanoacetamide with a mixture of the isomeric orthoamides 15 and 16. The 5,5-diamino-2,4-pentadienamide 11v attacks the orthoamide 9a at C3/C1. In the product 20 a cross conjugated multiple bond system is formed which contains an 1-aza-2,3-diamino function and a further ketene aminal function.