Efficient Method for the Synthesis of 1,5‐Benzodiazepine Derivatives Catalyzed by Monoammonium Salt of 12‐Tungstophosphoric Acid

Monoammonium salt of 12‐tungstophosphoric acid [(NH₄)H₂PW₁₂O₄₀] was found to be a practical, inexpensive, reusable, and efficient heterogeneous catalyst for the preparation of 1,5‐benzodiazepine derivatives of o‐phenylenediamine and ketones. The heteropolyacid‐based catalyst has the advantages of simple workup procedure, water insolubility with good activity, and high‐yielding reaction for the synthesis of 1,5‐benzodiazepine derivatives.     

Three-component reaction for synthesis of 2-amino-6-aryl-5-(phenylamino)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one derivatives in water

A new three-component domino reaction for the synthesis of 2-amino-6-aryl-5-(phenylamino)-3,7-dihydro-4H-pyrrolo[2,3-d]pyrimidin-4-one derivatives 4 using acetic acid as catalyst has been established. The reaction was performed in aqueous media using readily available and inexpensive 2,6-diaminopyrimidin-4(3H)-one 1 , 2,2-dihydroxy-1-arylethan-1-one 2 and aniline 3 as substrates. The simple and efficient one-pot three-component approach, inexpensive catalyst, green reaction media, make the present methodology a good synthetic procedure.     

The mass spectral fragmentation of 1a,3-disubstituted 4-benzoyl-1a,2,3,4- tetrahydrooxazirino

The mass spectrometric behaviour of four 1a,3-disubstituted 4-benzoyl-1a,2,3,4-tetrahydrooxazirino[2,3-a][1,5]benzodiazepines has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a neutral oxygen atom, or oxygen atom plus benzoyl or aryl radicals, or oxygen atom plus CO molecule to yield 2,3-dihydro-1H-1,5-benzodiazepine derivative ions, or 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions, which could further lose benzoyl to give 2,3-dihydro-1H-1,5-benzodiazepine ions. All compounds also show a tendency to eliminate a benzoyl radical to produce 1a,2,3,4-tetrahydrooxazirino[2,3-a][1,5]benzodiazepine ions. Both oxazirino[2,3-a][1,5]benzodiazepine ions and 2,3-dihydro-1H-1,5-benzodiazepine ions can undergo diazepine ring contraction rearrangement to yield benzimidazole ions by loss of propene or styrenes and other small fragments. The oxazirino[2,3-a][1,5]benzodiazepine ions [M(+)-PhCO] also undergo rearrangement reactions to form benzoxazole ions and benzimidazole ions. Copyright 1999 John Wiley & Sons, Ltd.     

Nucleophilic Substitution in 1,5-Benzodiazepin-2-ones

The reaction of 3-bromo-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one with cyclic amines gives 3-aminoalkyl-4-phenyl-2,3-dihydro-1H-1,5-benzodiazepin-2-one. Thiazolo[4,5-b][1,5]benzodiazepine was isolated along with the substitution product when thiourea was used.     

Montmorillonite K-10 clay catalyzed solvent-free synthesis of bis-indolylindane-1,3-dione, 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-dione and bisindolylindeno[1,2-b]quinoxaline under microwave irradiation

An environmentally benign protocol has been described for the synthesis of novel 2-(1′,3′-dihydro-1H-[2,3′]biindolyl-2′-ylidene)-indan-1,3-diones/bis-indolylindane-1,3-diones from ninhydrin and 3-substituted/unsubstituted indoles. It uses montmorillonite K-10 as catalyst in a solvent-free condition under microwave irradiation. The method was also used for the synthesis of novel bisindolylindeno[1,2-b]quinoxaline derivatives.     

Tetracyclic benzodiazepines. 3. Synthesis of the 2,3-dihydro-1h-quino[1,8-ab][1,5]benzodiazepine ring system,and derivatives of potential biological interest

The synthesis of the 2,3-dihydro-1H-quino[1,8-ab][1,5]benzodiazepine ring system is described. The key step involves a Bischler-Napieralski type cyclization of the formamide 3. This was achieved by refluxing in phosphorus oxychloride to effect a cyclodehydration to form the seven-membered central ring. A subgroup of 1H-quinobenzodiazepines bearing a pendant N-methylpiperazine substituent was synthesized by a similar cyclization of ureas of type 6. These derivatives 7 are structurally related to the antipsychotic drug clozapine.     

Design and characterization of Fe3O4/GO/Au-Ag nanocomposite as an efficient catalyst for the green synthesis of spirooxindole-dihydropyridines

A novel magnetic nanocomposite of Au-Ag nanoparticles anchored on Fe₃O₄/graphene oxide spheres (Fe₃O₄/GO/Au-Ag) was successfully fabricated by the layer-by-layer assembly technique. The prepared Fe₃O₄/GO/Au-Ag was fully characterized by Fourier-transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, thermogravimetric analysis (TGA), field-emission scanning electron microscopy (FE-SEM), energy-dispersive x-ray spectroscopy (EDS), transmission electron microscopy (TEM), and Raman spectroscopy. This nanocomposite showed unique catalytic performance for the synthesis of Spiro[indoline-3,5′-pyrido[2,3-d:6,5-d’]dipyrimidine]-pentaone derivatives by the three-component condensation reaction of isatins, barbituric acids and 6-amino uracil at room temperature and in aqueous media. The significant advantages of this protocol include highly stable, easily separable and reusable catalyst, simple operation, environmental friendliness and excellent yields.     

Deep eutectic solvent-mediated expedient multicomponent synthesis of oxazine scaffolds

A simple, efficient, and eco-friendly protocol for the synthesis of 1,3-oxazine derivatives, viz. 7-aryl-7,8-dihydro-6H-[1,3]dioxolo[4′,5′:4,5]benzo[1,2-e][1,3]oxazines and 3-aryl-3,4-dihydro-2H- naphtho[2,3-e][1,3]oxazine-5,10-diones, involving one-pot multicomponent condensation reaction of various amines and formaldehyde with sesamol/2-hydroxy-1,4-naphthoquinone, respectively, catalyzed by a choline chloride–oxalic acid deep eutectic solvent has been developed. The method offers several advantages, including mild reaction conditions, simple operating procedure, recyclable and biodegradable catalyst, short reaction times, and excellent yields of the target products.

     

Synthesis and characterization of some heterocyclic derivatives by cyclization of carbohydrate thiosemicarbazones. Part I

We report the synthesis of 2,3-dihydro-1,3,4-thiadiazoles and 1,3,4-thiadiazoles from 1,2:3,4-di-O-iso-propylidene-α-D-galacto-1,6-hexodialdo-1,5-pyranose thiosemicarbazone. The physical and spectro-scopic characterizations of the heterocyclic derivatives as well as the intermediate product are described. We present the prefered conformation in solution using computational calculations and spectroscopic data. The possibilities of chiral induction of the cyclization reaction are discussed.     

[BPy]HSO4 Acidic Ionic Liquid as a Novel,Efficient, and Environmentally Benign Catalyst for Synthesis of 1,5‐Benzodiazepines under Mild Conditions

A novel and simple ionic liquid methodology for the synthesis of 1,5‐benzodiazepines is described. 1‐Butylpyridinium hydrogen sulphate ([BPy]HSO₄), an acidic room‐temperature ionic liquid, as a novel and efficient catalyst, was synthesized and used in the preparation of a series of 1,5‐benzodiazepine derivatives by the reaction of o‐phenylenediamine with chalcones under mild conditions. This method is easy, efficient, environmentally friendly, economical, free of toxic catalysts, and has good yields for the formation of 1,5‐benzodiazepines     

Pd/C-Mediated Arylation Followed by I2-Catalyzed Hydration Strategy: Preparation of Functionalized Novel Indanone Derivatives

A simple and inexpensive synthesis of novel 2-(3-oxo-3-arylpropyl)-2,3-dihydro-1H-inden-1-one derivatives has been achieved via Pd/C-mediated arylation followed by I₂-mediated regioselective hydration of 2-(prop-2-ynyl)-2,3-dihydro-1H-inden-1-ones. A wide variety of 3-aryl substituted 2-propynyl indanone derivatives were conveniently prepared by using 10% Pd/C-PPh₃-CuI as a catalyst system, some of which were used to prepare the corresponding ketones via alkyne hydration in the presence of catalytic I₂. In an in vitro study a representative compound showed inhibition of PDE4B (phosphodiesterase type 4B) and binding with this protein in silico     

Green synthesis and antifungal activities of novel 3-(trifluoromethyl)-4,5-dihydro-1H-furo[2,3-c]pyrazole derivatives

Trifluoromethylated molecules, as well as pyrazol-3-one derivatives, are found in a wide range of biologically active compounds. An highly facile, green and mild access to substituted 3-(trifluoromethyl)-4,5-dihydro-1H-furo[2,3-c]pyrazole derivatives by the cascade [3 + 2] Michael/Alkylation of unsaturated pyrazolones with α-bromomalonate has been developed. The reactions can be performed in a easily available and environmentally benign solvent, and the substituted 3-(trifluoromethyl)-4,5-dihydro-1H-furo[2,3-c]pyrazole derivatives can be obtained in good to excellent yields by a simple purification step. The antifungal activities of these functional pyrazole derivatives were also evaluated and they showed high antifungal activity against Alternaria solani.     

MWCNTs-ZrO2 as a reusable heterogeneous catalyst for the synthesis of N-heterocyclic scaffolds under green reaction medium

A simple, efficient, and facile heterogeneous multi-walled carbon nanotubes-zirconia nanocomposite (MWCNTs-ZrO₂) has been synthesized using natural feedstock coconut juice (água-de-coco do Ceará). The synthesized catalyst was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, and X-ray photoelectron spectroscopy analysis. The heterogeneous nanocomposite has been used for one-pot synthesis of various N-heterocyclic compounds like pyrazoles, 1,2-disubstituted benzimidazoles, 2-arylbenzazoles, and 2,3-dihydroquinazolin-4(1H)-ones under green reaction medium at room temperature. This novel method has several advantages, such as short reaction time, simple work-up, excellent yield, and green reaction conditions. The catalyst was recycled up to four times without significant loss in catalytic activity.     

Lewis Acid-Mediated Ring Contraction of 2,4-Diaryl-2,3-dihydro-1H-1,5-benzodiazepines: Access to 2-Aryl-1-styrylbenzimidazoles

2,4-Diaryl-2,3-dihydro-1H-1,5-benzodiazepines readily undergo a ring contraction to generate 2-aryl-1-styrylbenzimidazoles in the presence of some Lewis acids. Copper acetate shows high efficiency compared with other Lewis acids. The ring contraction includes Lewis acid-catalyzed intramolecular addition, ammonium-induced ring-opening of the generated four-membered azetidine ring, deprotonation, and amine-promoted nucleophilic styryl 1,2-shift and elimination. Copper acetate serves as Lewis acid, base, and oxidant. The current reaction provides an efficient method for the convenient synthesis of 2-aryl-1-styrylbenzimidazole derivatives from readily available 2,4-diaryl-2,3-dihydro-1H-1,5-benzodiazepines.     

Potassium dihydrogen phosphate-catalyzed synthesis of benzylpyrazolyl coumarin and pyrano [2,3-c] pyrazole derivatives via cascade—One-pot—Multicomponent reaction

A simple one-pot protocol for the synthesis of benzylpyrazolyl coumarin and pyrano [2,3-c] pyrazole derivatives in the presence of potassium dihydrogen phosphate (KH₂PO₄) has been developed. This cascade reaction provides many advantages like environmentally benign reaction, mild reaction conditions, inexpensive catalyst, simple operation, easy workup procedure, a wide range of functional groups in good to excellent yields, and no need for column purification.     

Green and highly efficient synthesis of pyranopyrazoles in choline chloride/urea deep eutectic solvent

A simple and efficient multicomponent protocol, using ammonium deep eutectic solvent as a dual catalyst and environmentally benign reaction medium, is developed for the synthesis of dihydropyrano[2,3-c]pyrazole derivatives. This operationally simple protocol does not involve tedious workup or purification, affording the target compounds in short reaction times and excellent yields and avoiding the use of environmentally hazardous solvents and catalysts.     

Azines and azoles: CXXVI. First example of a novel heterocyclic system: Pyrimido[1,6-<Emphasis Type="Italic">a</Emphasis>][1,5]benzodiazepines

4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones readily undergo acylation at the N¹ atom of the benzodiazepine system by the action of acetic anhydride. Heating of the acetylated products in boiling dimethylformamide leads to the formation of 75–93% of the corresponding 7-acetyl-6-R-6,7-dihydropyrimido[1,6-a][1,5]benzodiazepine-1,3-diones that are derivatives of hitherto unknown fused heterocyclic system, pyrimido[1,6-a][1,5]benzodiazepine. 4-Hydroxy-5-(2-R-2,3-dihydro-1H-1,5-benzodiazepin-4-yl)-2H-1,3-thiazine-2,6-diones are converted into 1-(2-aminophenyl)-6-(2-R-vinyl)uracils on heating in boiling DMF.     

Efficient four‐component synthesis of spiroindole derivatives catalysed by a versatile and reusable nano‐paramagnetic catalyst

A simple, efficient and environmentally benign route was developed for the preparation of spiro(indoline‐3,4‐pyrano[2,3‐c ]pyrazole) derivatives with good yields from condensation of isatins, malononitrile (or ethyl cyanoacetate), hydrazine hydrate and ethyl acetoacetate catalysed by PFu@Fe₃O₄ nanocomposite. The use of easily available catalyst, shorter reaction times, better yields, simplicity of reaction, heterogeneous system and easy work‐up are the advantages of the method presented. Characterization of the catalyst was performed using Fourier transform infrared spectroscopy, X‐ray diffraction and transmission electron microscopy.     

In(OTf)3‐Catalyzed Synthesis of Functionalized 1,5‐Benzodiazepines from o‐Phenylenediamine and Alkyl Propiolates under Solvent‐Free Reaction Conditions

A simple, environmental‐friendly, and practical method for the synthesis of benzodiazepine derivatives through a reaction of substituted o‐phenylenediamines with alkyl propiolates has been developed. The reactions generated the 1,5‐benzodiazepines in good to excellent yields in the presence of catalytic amount of In(OTf)₃ under solvent‐free reaction conditions.     

Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid supported montmorillonite K-10 clay-catalysed one-pot multi-component synthesis of chromeno[2,3-b]indoles

One-pot three-component synthesis of twelve different chromeno[2,3-b]indole derivatives were achieved by the condensation of β-naphthol, oxindole and various substituted aldehydes. Two more chromeno[2,3-b]indole derivatives were also synthesized through one-pot two-component condensation of salicylaldehyde with oxindole/chlorooxindole. Both the condensations were achieved by using Keggin-type heteropoly-11-molybdo-1-vanadophosphoric acid, H₄[PVMo₁₁O₄₀] supported on montmorillonite K-10 clay for about 10% as catalyst under environmentally benign solvent-free reaction condition. Shorter reaction time, excellent yield of product, sustainability of catalytic material and simple workup procedure under green experimental conditions are the advantages of this protocol.