KOH In DMF Research Articles

Regio- and Chemoselective Access to Dihydrothiophenes and Thiophenes via Halogenation/Intramolecular C(sp2)-H Thienation of α-Allyl Dithioesters at Room Temperature.

An operationally simple, practical, and efficient cascade approach employing α-allyl dithioesters and NBS/NIS has been achieved to access a series of dihydrothiophenes and thiophenes containing diverse functional groups of different electronic and steric natures in good to excellent yields at room temperature in open air. The reaction proceeds via the electrophilic addition of a halogen source (NBS/NIS) to an allylic double bond, followed by intramolecular regio- and chemoselective S-cyclization. This protocol avoids potential toxicity and tedious work-up conditions, and features easy synthesis from readily available starting materials under catalyst-free conditions. Furthermore, 4,5-dihydrothiophenes were aromatized to thiophenes by treatment with KOH in DMF at room temperature. A probable mechanism for the formation of dihydrothiophenes and thiophenes from α-allyl dithioesters has been suggested. Notably, a large-scale experiment and the transformations of products indicated the potential utility of this reaction compared to competing processes for the synthesis of 4,5-dihydrothiophenes and thiophenes.

From radicals destabilization to stable fullerenol nanoaggregates

• Fullerenol radicals were prepared with C60 and KOH in DMF under nitrogen atmosphere. • Radicals oxidation promoted by air contributes to increasing modification degree. • Nanoparticles are formed after the oxidation of fullerenol radicals. • Electrostatic and solvation interactions provide stability for nanoparticles in DMF. • Concentrated dispersions of fullerenols in DMF are lyophilic and stable. Fullerenols are fullerene derivatives enriched on hydroxyl groups that are obtained usually as nanoparticles nanoaggregates dispersed in water. These materials are used in energy-related and biological applications, and they have been reported as radical scavengers, antioxidants and stable radicals. However, most synthesis demand highly toxic solvents to dissolve precursor fullerene, potentially dangerous reagents such as hydrogen peroxide, and prolonged reactions. Herein, a novel and faster procedure for fullerenol preparation based on the reaction between fullerene C 60 and potassium hydroxide in a polar solvent is reported. Initially, fullerenol radicals are formed, followed by air oxidation that promotes charge loss and simultaneous clustering into nanoparticles nanoaggregates with diameters up to 90 nm. Dried fullerenol has about 12 oxygenated groups per C 60 . Then, an aqueous dispersion was prepared with dispersed material having lyophobic behavior but maintaining the modification degree. This low-modified fullerenol remains dispersed indefinitely in an organic medium due to electrostatic and solvation colloidal interactions arising from functional groups. As a result, stable organic dispersions with concentrations up to 10 mg mL −1 were obtained. This work opens new possibilities on fullerenol preparation and new perspectives concerning achieving the achievement of stable colloids of carbon nanomaterials due to the unprecedented stability and mass concentration of the reported fullerenol dispersions.

Synthesis and Some Properties of New 5-Hydroxy-2-[(hetarylthio)methyl]-4H-pyran-4-ones

The reaction of 2-thioxoazines with chlorokojic acid in the presence of KOH in DMF led to the formation of new hybrid molecules containing fragments of kojic acid and azaheterocycle linked by the SCH2 spacer. In silico prediction of bioavailability parameters was carried out, possible protein targets were predicted by the protein ligand docking method.

Facile Assembly of Carbazolyl-Derived Phosphine Ligands and Their Applications in Palladium-Catalyzed Sterically Hindered Arylation Processes

Phosphine ligands embodying a carbazolyl motif have been found to be successful in many palladium-catalyzed biaryl syntheses and direct C–H bond arylation processes. Here, a practical scaled-up synthesis of a series of carbazolyl-derived phosphine ligands, the PhenCarPhos series, is described. The original protocol for accessing the target ligand skeleton via aromatic C–N bond formation is limited by the use of a substoichiometric amount of copper salt and diamine catalysts, which both add cost and generate purification problems (significant amounts of side products and copper residues). In order to develop a more attractive and scalable synthetic pathway, a simple nucleophilic substitution method was attempted involving simple heating of 1-bromo-2-fluorobenzene, a carbazole derivative, and KOH in DMF without inert atmosphere protection. This route enables the large-scale synthesis of the desired ligand skeletons and minimizes the association of inseparable reduction side products. Particular examples of the use of these ligands in Pd-catalyzed sterically hindered arylation processes are also shown.

A one-pot synthesis of bis(phenylimino)thiazolidines from ketene N,S-acetals and [Formula: see text],[Formula: see text]-diphenyloxalimidoyl dichloride.

A synthesis of functionalized 4,5-bis(phenylimino)-1,3-thiazolidine-2-ylidenes via a simple reaction between ketene [Formula: see text]-acetals (derived from isothiocyanates and acetonitrile derivatives) with N,[Formula: see text]-diphenyloxalimidoyl dichloride in the presence of KOH in DMF is described. When CS[Formula: see text] was used as the heterocumulene component, the reaction led to the formation of 4,5-bis(phenylimino)-1,3-dithiolan-2-ylidene derivatives, in moderate to good yields.

Design, Synthesis, and Characterization of 1, 3‐disubstituted‐1,4‐benzodiazepine Derivatives

The 2‐amino‐4′‐flouro‐benzophenone (1) that was reacted with chloroacetylchloride to afford 2‐chloro‐N‐(2‐(4′‐fluorobenzoyl) phenyl)acetamide (2) was subsequently converted to 1,4‐benzodiazepines (3) by the modification of the known hexamethylenetetramine based cyclization reaction developed by Blazevic and Kajfez. Thus, obtained product (3) was reacted with a variety of alkyl halide using KOH in DMF to give 1‐substituted‐5‐(4‐fluorophenyl)‐1H‐benzo[e][1,4]diazepin‐2(3H)‐one (4a, 4b). To achieve 1, 3‐disubstituted 1, 4‐benzodiazepines (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h, 5i, 5j, 5k, 5l, 5m, 5n, 5o, 5p, 5q, 5r, 5s, 5t), 1‐substituted‐5‐(4‐fluorophenyl)‐1H‐benzo[e][1,4]diazepin‐2(3H)‐one (4a, 4b) was treated with various aromatic aldehydes in the presence of KOH in toluene.

Alternative Route for the Synthesis of New Derivatives of Benzimidazo[2′,1′:2,3] thiazolo[5,4-d]pyrimidine

A series of new benzimidazothiazolopyrimidines were synthesised through a route involving successive nucleophilic substitution of 5-bromo-2,4-dichloro-6-methylpyrimidine with 2-mercaptobenzimidazole and secondary amines, respectively and eventually cyclisation in the presence of KOH in DMF. The structures of the newly synthesised compounds were characterised by their spectral data and elemental analysis.

Synthesis and Antimicrobial Evaluation of Some Novel Thiazole, Pyridone, Pyrazole, Chromene, Hydrazone Derivatives Bearing a Biologically Active Sulfonamide Moiety

This study aimed for the synthesis of new heterocyclic compounds incorporating sulfamoyl moiety suitable for use as antimicrobial agents via a versatile, readily accessible N-[4-(aminosulfonyl)phenyl]-2-cyanoacetamide (3). The 2-pyridone derivatives were obtained via reaction of cyanoacetamide with acetylacetone or arylidenes malononitrile. Cycloaddition reaction of cyanoacetamide with salicyaldehyde furnished chromene derivatives. Diazotization of 3 with the desired diazonium chloride gave the hydrazone derivatives 13a–e. Also, the reactivity of the hydrazone towards hydrazine hydrate to give Pyrazole derivatives was studied. In addition, treatment of 3 with elemental sulfur and phenyl isothiocyanate or malononitrile furnished thiazole and thiophene derivatives respectively. Reaction of 3 with phenyl isothiocyanate and KOH in DMF afforded the intermediate salt 17 which reacted in situ with 3-(2-bromoacetyl)-2H-chromen-2-one and methyl iodide afforded the thiazole and ketene N,S-acetal derivatives respectively. Finally, reaction of 3 with carbon disulfide and 1,3-dibromopropane afforded the N-[4-(aminosulfonyl) phenyl]-2-cyano-2-(1,3-dithian-2-ylidene)acetamide product 22. All newly synthesized compounds were elucidated by considering the data of both elemental and spectral analysis. The compounds were evaluated for both their in vitro antibacterial and antifungal activities and showed promising results.

Microwave assisted base dependent regioselective synthesis of partially reduced chromenes, isochromenes and phenanthrenes

We have reported a microwave assisted base directed regioselective synthesis of partially reduced chromenes, isochromenes and phenanthrenes. Functionalized 4-(piperidin-1-yl)-5,6-dihydro-2H-benzo[h]-chromen-2-one-3-carbonitriles have been used as precursors, which on reaction with functionalized acetophenones in the presence of KOH in DMF under microwave irradiation yield (Z)-2-(2-aryl-5,6-dihydro-4H-benzo[f]isochromen-4-ylidene)acetonitriles. The use of NaH in DMF provides 3-aryl-1-(piperidin-1-yl)-9,10-dihydro phenanthrene-2-carbonitriles in excellent yield regioselectively. The use of cyclohexanone as a nucleophile source yields (Z)-2-(3,4,7,8-tetrahydro-1H-naphtho[2,1-c]chromen-6(2H)-ylidene)acetonitriles. The structure and geometry of isochromene have been proved without any ambiguity by single crystal X-ray diffraction.

Facile synthesis and antimicrobial evaluation of some new heterocyclic compounds incorporating a biologically active sulfamoyl moiety.

A facile and convenient synthesis of new heterocyclic compounds containing a sulfamoyl moiety suitable for use as antimicrobial agents was reported. The precursor 3-oxo-3-phenyl-N-(4-sulfamoylphenyl)propionamide was coupled smoothly with arenediazonium salt producing hydrazones which reacted with malononitrile or triethylorthoformate affording pyridazine and triazine derivatives, respectively. Also, the reactivity of the same precursor with DMF-DMA was followed by aminotriazole; aromatic aldehydes was followed by hydrazine hydrate, triethylorthoformate, or thiourea affording triazolo[1,5-a]pyrimidine, pyrazole, acrylamide, and dihydropyrimidine derivatives, respectively. On the other hand, treatment of the precursor propionamide with phenyl isothiocyanate and KOH in DMF afforded the intermediate salt which was treated with dilute HCl followed by 2-bromo-1-phenylethanone affording carboxamide derivative. While the same intermediate salt reacted in situ with chloroacetone, ethyl 2-chloroacetate, 3-(2-bromoacetyl)-2H-chromen-2-one, methyl iodide, or 2-oxo-N-phenylpropane hydrazonoyl chloride afforded the thiophene, ketene N,S-acetal, and thiadiazole derivatives, respectively. The structure of the new products was established based on elemental and spectral analysis. Antimicrobial evaluation of some selected examples from the synthesized products was carried out whereby four compounds were found to have moderate activities and one compound showed the highest activity.

INVESTIGATIONS OF 2,3'-BIQUINOLYL. 7. THIOLATION OF 1-ALKYL-3-(2-QUINOLYL)QUINOLINIUM HALIDES

Thiolation of 1-alkyl-3-(2-quinolyl)quinolinium halides by a mixture of sulfur with KOH in DMF leads to formation of 1'-alkyl-1',4'-dihydro-2,3'-biquinolyl-4'-thiones, rearrangement of which in boiling ethylene glycol makes it possible to obtain 4'-alkylthio-2,3'-biquinolyls. Authors: D. V. Moiseev, A. V. Aksenov, and Yu. I. Smushkevich. English Translation in Chemistry of Heterocyclic Compounds , 2000, 36 (4), pp 439-442 http://link.springer.com/article/10.1007/BF02269542

SYNTHESIS AND ANTIMICROBIAL ACTIVITIES OF BENZOTHIOPHENE DERIVATIVES

3-Chlorobenzothiophene-2-carbonyl chloride 1 was reacted with 4-aminoacetophenone in acetone to give compound 2. In order to prepare chalcones 3a-d, compound 2 was condensed with various aldehydes in the presence of KOH in DMF. These chalcones 3a-d on cyclization with urea, thiourea, hydroxylamine hydrochloride, phenyl hydrazines and hydrazine hydrate gave the corresponding oxapyrimidines 4a-d, isoxazolines 5a-d, pyrazoles 6a-h, pyrazolines 7a-d and thiopyrimidines 8a-d, respectively. The structures of all the synthesized compounds were confirmed by spectral data and had been screened for antibacterial activity.

Thiazolo[4,5-d]pyrimidines: synthesis and antibacterial evaluation

The reaction of 4-amino-5-bromo-2-chloro-6-methylpyrimidine (1) with carbon disulfide in the presence of KOH in DMF quantitatively gave 5-chloro-7-methylthiazolo[4,5-d] pyrimidine-2 (3H)-thione (2) which was then alkylated at the sulfur atom with various alkyl halides in the presence of Et3N in acetonitrile to give alkylthio derivatives 3. The substitution of the chlorine atom in 3 with morpholine was also investigated. The synthesized compounds were subjected to antibacterial evaluations.

Facile synthesis of 2,6‐diaryl‐4‐secondary aminonicotinonitriles and highly substituted unsymmetrical 2,2′‐bipyridines

Abstract magnified imageThe ring transformation of 2H‐pyran‐2‐one by N‐aryl amidine in the presence of KOH in DMF at room temperature resulted in a facile synthesis of the 2,6‐diaryl‐4‐secondary aminonicotinonitrile and highly substituted unsymmetrical 2,2′‐bipyridines in moderate yield. J. Heterocyclic Chem., (2010).

An Expeditious Concise Synthesis of Benzo[b]pyrano[2,3-d]oxepines and Dibenzo[b,d]oxepines

An efficient concise synthesis of 4-methylthio-2-oxo-5,6-dihydro-2 H-benzo[ B]pyrano[2,3- D]oxepine-3-carbonitriles has beendelineated through condensation-cyclization of 3,4-dihydro-2 H-benzo[ B]oxepin-5(2 H)-ones and methyl 2-cyano-3,3-dimethylthioacrylatein DMF using powdered KOH as a base. A base--induced reactionof 3,4-dihydro-2 H-benzo[ B]oxepin-5(2 H)-ones and6-aryl-4-methylthio-2 H-pyran-2-one-3-carbonitrilein the presence of powdered KOH in DMF gave an isomeric mixtureof ( E)- and ( Z)-2-(4-phenyl-5,6-dihydro-2 H-benzo[ B]pyrano[2,3- D]oxepin-2-ylidene)acetonitriles.However, the ring transformation of 6-aryl-4-(s EC-amino)-2 H-pyran-2-one-3-carbonitriles from 3,4-dihydro-2 H-benzo[ B]oxepin-5(2 H)-ones under analogous reaction conditionsexclusively gave 8-phenyl-10-( SEC-amino)-6,7-dihydrodibenzo[ B, D]oxepine-11-carbonitriles.

Substituent‐Induced Regioselective Synthesis of 1,2‐Teraryls and Pyrano[3,4‐c]pyran‐4,5‐diones from 2H‐Pyran‐2‐ones.

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Substituent-induced regioselective synthesis of 1,2-teraryls and pyrano[3,4- c]pyran-4,5-diones from 2 H-pyran-2-ones

Substituent-controlled regioselective synthesis of highly functionalized 1,2-teraryls 3a– k has been achieved through ring transformation of 6-aryl-4-(pyrrolidin-1-yl/piperidin-1-yl)-2 H-pyran-2-one-3-carbonitriles 1a– g by aryl acetones 2a– c in the presence of powdered KOH in DMF in very good yield. Under similar reaction conditions, 6-aryl-4-methylsulfanyl-2 H-pyran-2-ones 5a– f afforded 1,7-diaryl-2-methyl-4 H,5 H-pyrano[3,4- c]pyran-4,5-diones 6a– j as major products and 3,4-diaryl-2-methyl-6-methylsulfanylbenzonitriles as minor constituents 7a– j.

Investigations of 2,3′-biquinolyl. 7. Thiolation of 1-alkyl-3-(2-quinolyl)quinolinium halides

Thiolation of 1-alkyl-3-(2-quinolyl)quinolinium halides by a mixture of sulfur with KOH in DMF leads to formation of 1′-alkyl-1′,4′-dihydro-2,3′-biquinolyl-4′-thiones, rearrangement of which in boiling ethylene glycol makes it possible to obtain 4′-alkylthio-2,3′-biquinolyls.

A general method for the alkaline cleavage of enolisable ketones

An efficient method is described for the cleavage of enolisable aryl methyl and aryl ethyl ketones using an excess of KOH in DMF at an elevated temperature. It presents a general hydrolytic method yielding aromatic carboxylic acids, and is complementary to the widely used oxidative methods for ketone cleavage.

Intramolecular cyclization of 2-(o-carboran-1-yl) methylthio-3-cyanopyridines in basic conditions

Substituted 2-(o-carboran-1-yl)methylthio-3-cyanopyridines and-pyrimidines undergo Thorpe-Ziegler cyclization under the influence of KOH in DMF to give the corresponding thienopyridines and thienopyrimidines. The reaction is complicated by a side reaction in which thecloso-carborane nucleus is converted to anido-system. The yield of thienopyridines containing acloso-carborane unit is increased by introduction of an acceptor substituent in the pyridine ring. Destruction of thecloso-carborane nucleus is not observed with the pyrimidine derivatives. The structures of the series of new carborane-containing thienopyridines and pyrimidines was confirmed by spectroscopic methods.