Palladium‐Free Copper‐Catalyzed Coupling Reaction of Aryl Iodides and Terminal Acetylenes in Water

An efficient and general method has been developed for palladium‐free copper‐catalyzed cross‐coupling reactions of aryl iodides and terminal acetylenes under microwave irradiation in water, producing various alkynes in excellent yields. This process can also be successfully carried out under reflux in an oil bath.     

Facile Synthesis of Pyrazolo[3,4‐d]pyrimidines and Pyrimido[4,5‐d]pyrimidin‐4‐one Derivatives

Pyrazolopyrimidine and pyrimidopyrimidine derivatives have shown a wide range of biological activities such as acting as A₁ adenosine receptors, kinase insert domain receptor (KDR), Rous sarcoma oncogene (Src), epidermal growth factor receptor (EGFR), antiproliferative, dihydrofolate reductase (DHFR), antimicrobial, antifungal, and lipid peroxidation. Because of this wide range of activities, we have synthesized pyrazolo[3,4‐d]pyrimidines and pyrimido[4,5‐d]pyrimidin‐4‐one derivatives.     

Copper‐Free,Efficient, Palladium (II)‐Catalyzed Coupling of Unactivated Aryl Iodides with Terminal Alkynes

Palladium(II)‐catalyzed coupling of terminal alkynes with unactivated aryl iodides occurs at room temperature in good to excellent yields in the presence of tetrabutylammounium bromide as additive and piperidine as base in a tetrahydrofuran–water solution without addition of any cuprous salts.     

Regioselective Synthesis of Thiopyrano[3,2‐c][1]benzothiopyran‐5(2H)‐one and Thieno[3,2‐c][1]benzothiopyran‐4(2H)‐one

4‐Mercaptothiocoumarin was alkylated with different propargylic and allylic halides under phase‐transfer‐catalyzed conditions in the presence of tetrabutylammonium bromide (TBAB) or benzyl triethylammonium chloride (BTEAC) catalyst in dichloromethane–aqueous NaOH solution (1%) at room temperature. These 4‐thiopropynyl and thioallyl thiocoumarins were then refluxed in chlorobenzene and quinoline to give thiopyrano[3,2‐c][1]benzothiopyran‐5(2H)‐one and thiopyrano[3,2‐c][1]benzothiopyran‐4‐one respectively.     

Synthesis of 3‐Substituted 2‐Thioxo‐2,3‐dihydro‐1H‐benzofuro[3,2‐ d ] pyrimidin‐4(1H)‐ones

With the purpose of searching for new biologically active compounds, a method of synthesis of new heterocyclic systems [3‐alkyl(aryl)‐2‐thioxo‐2,3‐dihydro‐1H‐benzofuro[3,2‐d]pyrimidin‐4(1H)‐ones] has been developed. The method is based on the interaction of ethyl 3‐isothiocyanato‐1‐benzofurane‐2‐carboxylate in 2‐propanol with amines in the presence of an equimolecular quantity of triethylamine.     

Copper bis(2,2,6,6-Tetramethyl-3,5-heptanedionate)–Catalyzed Coupling of Sodium Azide with Aryl Iodides/Boronic Acids to Aryl Azides or Aryl Amines

This work reports an efficient protocol for the coupling reaction of aryl iodides/boronic acids with sodium azide to aryl azides/amines in the presence of copper bis(2,2,6,6-tetramethyl-3,5-heptanedionate) Cu(TMHD)₂ catalyst. The Cu(TMHD)₂ catalyst is a structurally well-defined, O-containing, air- and moisture-stable, transition-metal complex and works at mild reaction conditions. It was observed that aryl azides can be reduced further to corresponding aniline derivatives using the same catalyst under basic reaction conditions for a prolonged period.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Glycosylation of 4‐Aryl‐1‐thioxo[1,2,4] triazolo[4,3‐a] quinazolin‐5(4H)‐one

Reaction of 4‐aryl‐1‐thioxo [1,2,4] triazolo [4,3‐a] quinazolin‐5 (4H)‐ones (2a,b) with acetylated glycosyl bromides 3a–c under alkaline conditions afforded the corresponding S‐glycoside derivatives 4, 5 and N‐glycoside derivatives 6, 7. Oxidation of S‐glycosyl derivatives 4, 5 with m‐chloroperbenzoic acid yielded the corresponding sulphones 8, 9, whereas the N‐glycosyl derivatives 6, 7 yielded 1‐oxo derivatives 10, 11. However their O‐deacetylation with sodium methoxide in methanol caused cleavage of the S‐glycosyl residue and gave N ²‐glycosylated analogues 12, 13, 14 and 15.     

Studies on Amine Oxide Rearrangement: Synthesis of Pyrrolo[3,2‐c][1]benzothiopyran‐4‐one

A methodology, based on tandem [2,3] and [3,3] sigmatropic rearrangement, has been described for the synthesis of hitherto unreported, potentially bioactive pyrrolo[3,2‐c][1]benzothiopyran‐4‐ones (6a–g) derivatives.     

Synthesis of Fused Tetrazolo[1,5‐c] pyrrolo[3,2‐e]pyrimidines and Their Reductive Conversion to New 4‐Aminopyrrolo[2,3‐d]pyrimidines

Some new 7,9‐substituted 7H‐1,2,3,4‐tetrazolo[1,5‐c]pyrrolo[3,2‐e]pyrimidines 5 have been synthesized either by diazotization of 4‐hydrazino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines 4 obtained by hydrazinolysis of 4‐chloro‐5,7‐disubstituted 7H‐pyrrolo[2,3‐d]pyrimidines 3 or via a substitution reaction between 3 and sodium azide. 5,7‐Disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidin‐4(3H)‐ones 2 were obtained by cyclocondensation of 1,4‐disubstituted 2‐amino‐3‐cyanopyrroles 1 with formic acid, which, on chlorination using phosphorus oxychloride, afforded 3. 2‐Amino‐3‐cyanopyrroles 1 were synthesized from the reaction between (2-bromo-1-(4-fluorophenyl) ethylidene) propanedinitrile and substituted aromatic amines under Gewald reaction conditions. A novel route for the synthesis of 4‐amino‐5,7‐disubstituted‐7H‐pyrrolo[2,3‐d]pyrimidines 6 by the reductive ring cleavage of 5 has been reported.     

Clean Procedure for Synthesis of Chromeno[4,3‐b]benzo [f]quinolin‐6‐one Derivatives: Reaction of N‐arylidenenaphthalen‐2‐amine with 4‐Hydroxycoumarin in Aqueous Media

A short and simple synthesis of chromeno[4,3‐b]benzo[f]quinolin‐6‐one derivatives was accomplished in good to high yields via the reaction of N‐arylidenenaphthalen‐2‐amine with 4‐hydroxycoumarin in aqueous media catalyzed by TEBAC. The structures were established by spectroscopic data and further confirmed by X‐ray analysis. In addition, water was chosen as a green solvent.     

A Facile Synthesis of Novel [4‐(Aryl)‐3a,4,5,9b‐tetrahydrocyclopenta[c]quinolin‐8‐ylmethyl]‐8′‐(4′‐aryl)‐3a′,4′,5′, 9b′‐tetrahydro‐3H‐cyclopenta[c]quinolines: Indium Trichloride Catalyzed Intermolecular Imino Diels–Alder Reaction of Cyclopentadiene with Schiff's Bases

Abstract

A simple and efficient method for the synthesis of the title compounds from Schiff's bases derived from 4,4′‐diaminodiphenylmethane and excess of cyclopentadiene using anhydrous indium trichloride as a catalyst is described.     

L‐Proline‐Catalyzed Asymmetric Direct Aldol Reaction of Heteroaromatic Aldehydes and Acetone: Improvement of Catalytic Efficiency in Ionic Liquid bmim [BF4]

l‐proline in bmim [BF₄] ionic liquid has been successfully used as an efficient and reusable catalyst for the direct asymmetric aldol reaction of acetone with different heteroaromatic aldehydes to afford higher selectivity of the aldol products with good enantioselectivity.     

Synthesis of 4,4‐Disubstituted‐4H‐benzo[d][1,3]oxathiin‐2‐ones,a New Class of Compounds

4,4‐Dialkyl and 4,4‐diaryl‐4H‐benzo[d][1,3]oxathiin‐2‐ones were synthesized by the reaction of 2‐(mercapto‐phenyl)‐dialkyl‐ (or diaryl)‐methanol with CDI in excellent yield. The 2‐(mercaptophenyl)‐dialkyl‐ (or diaryl)‐methanols were prepared by the reaction of commercially available methylthiosalicylate with an appropriate alkyl or aryl Grignard reagent.     

Novel Pyridazine Fused Heterocyclic System: A New Route for the Synthesis of 2‐Alkyl/Aryl[1,3,4]Thiadiazole[2′,3′:2,3] Imidazo[4,5‐d]Pyridazin‐8(7H)‐One

A series of novel imidazo[2,1‐b][1,3,4]thiadiazole fused pyridazinones have been synthesized in moderate yields by the reaction of 2‐alkyl/arylimidazo[2,1‐b] [1,3,4]thiadiazole‐6‐carbohydrazides under Vilsmeier–Haack reaction conditions. This simple methodology has utility for the synthesis of various fused heterocyclic systems.     

Synthesis of Some Novel 2,3,4,8,9‐Pentahydro‐7‐(4‐haloaryl)‐pyrazolo[5,1‐e]benzo[1,5]oxazocines and 2,3(erythro), 7,8‐Tetrahydro‐2‐aryl‐3‐(4‐fluoro‐3‐methylbenzoyl)‐6‐(4‐haloaryl)pyrazolo[5,1‐d] Benzo[1,4]oxazepines via Solid–Liquid PTC

In this communication, a simple and straightforward procedure for the heterocyclization of 1H‐4,5‐dihydro‐3‐(4‐haloaryl)‐5‐substituted phenylpyrazoles (4) with 1‐bromo‐3‐chloropropane and 2,3‐dibromo‐1‐(4‐fluoro‐3‐methylphenyl)‐3‐phe‐ nylpropanone affording 2,3,4,8,9‐pentahydro‐7‐(4‐haloaryl)pyrazolo[5,1‐e]benzo[1,5] oxazocines 5 and regioselective synthesis of 2,3(erythro),7,8‐tetrahydro‐2‐ aryl‐3‐(4‐fluoro‐3‐methylbenzoyl)‐6‐(4‐halophenyl)pyrazolo[5,1‐d]benzo[1,4]oxa‐ zepines 6, respectively, via solid–liquid PTC is reported. All the synthesized compounds have been characterized on the basis of their spectral studies (IR, PMR, and MS) and analytical data.     

Heck Reaction of Iodoarenes with Methyl Acrylate Catalyzed by Cyclopalladated Complexes of Tertiary Arylamines Immobilized in Ionic Liquid [Bmim]~+BF_4~-

IntroductionAsoneofthemostimportantC—Cformationreactionsandone stepmethodforthearylationofolefins ,Heckre actionhasattractedmuchinterest.1However ,thereactionusuallyneedsarelativelylargeamountofpalladiumcata lyst (>1mol%)forsatisfactoryconversions .Recently ,avarietyofpalladacyclesincorporatingcyclometallatedphos phine ,2 phosphite ,3 carbene ,4 imine5andoxime6havebeenreported .Theuseofcatalystswithnitrogen basedligandswasdemonstratedtopossessveryhighactivity .Wehavereportedthecyclopalladat…     

One‐Pot Synthesis of 2‐Amino‐4‐aryl‐3‐carbalkoxy‐7,7‐dimethyl‐5,6,7,8‐tetrahydrobenzo[b]pyran Derivatives Catalyzed by KF/Basic Al2O3 Under Ultrasound Irradiation

Abstract

Synthesis of 2‐amino‐4‐aryl‐3‐carbalkoxy‐7,7‐dimethyl‐5‐oxo‐5,6,7,8‐tertrahydrobenzo[b]pyran derivatives was carried out in 81–98% yields by one‐pot condensation of aromatic aldehydes with cyanoacetic esters and 5,5‐dimethyl‐1,3‐cyclohexanedione catalyzed by KF/basic Al₂O₃ at room temperature under ultrasound irradiation.     

The Reaction of 2-Ethoxy-3-Phenylbenzo[D]-1,3, 2-Oxazaphosphorin-6-One with α-Ketocarboxylic Acid Esters: Synthesis of Benzo[d]-1,3,2-Oxazaphosphepine Derivatives

Abstract

The reactions of 2-ethoxy-3-phenylbenzo[d]-1,3,2-oxazaphosphorin-6-one with R-carbonylcarboxylic acids ethyl esters (R = CF₃, Ph, and Me) lead to the formation of seven-membered heterocycles, 2-ethoxy-9-ethoxycarbonyl-2,8-dioxo-3-phenyl-9-R-benzo[d]-1,3,2-oxazaphosphepines.     

Facile One‐Pot Synthesis of 3‐{2‐[5‐Hydroxy‐4‐(2‐hydroxy‐ethyl)‐3‐methyl‐pyrazol‐1‐yl]‐thiazol‐4‐yl}‐chromen‐2‐ones via a Three‐Component Reaction

Reaction of 3‐(2‐bromo‐acetyl)‐chromen‐2‐one with thiosemicarbazide and 2‐acetylbutyro lactone in anhydrous ethanol gave 3‐{2‐[5‐hydroxy‐4‐(2‐hydroxy‐ethyl)‐3‐methyl‐pyrazol‐1‐yl]‐thiazol‐4‐yl}‐chromen‐2‐one in good yields.     

Rapid Access for the Synthesis of 1‐N‐Methyl‐spiro[2.3′]oxindole‐spiro[3.7″] (3″‐Aryl)‐5″‐methyl‐3″,3a″,4″,5″,6″,7″‐hexahydro‐2H‐pyrazolo[4,3‐c]pyridine‐4‐aryl‐pyrrolidines Through Sequential 1,3‐Dipolar Cycloaddition and Annulation

The 1,3‐dipolar cycloaddition of an azomethine ylide, generated from isatin and sarcosine by a decarboxylative route with various p‐substituted 3,5 bis(aryl methylidene)N‐methyl‐4‐piperidinones in refluxing methanol, proceeded regioselectively to give novel dispiroheterocycles. The product on subsequent annulation with hydrazine hydrate afforded 1‐N‐methyl‐spiro[2.3′]oxindole‐spiro[3.7″](3″‐aryl)‐5″‐methyl‐3″,3a″,4″,5″,6″,7″‐hexahydro‐2H‐pyrazolo[4,3‐c]pyridine‐4‐aryl‐pyrrolidines in good yield.