A facile and regioselective synthesis of 2,5-disubstituted pyrroles via gold-catalyzed cycloisomerization of acetylenylaziridines

Gold-catalyzed cycloisomerization reaction of acetylenylaziridines provides 2,5-disubstituted pyrroles in high yields. The presence of protic species accelerates the reaction rate and improves the yields of pyrrole products.     

Fast, efficient, mild, and metal-free synthesis of pyrroles by domino reactions in water

(E)-β-Bromonitrostyrenes react with enaminones in water to afford pyrroles in excellent yields. The domino reaction constitutes a new, mild, and environmentally benign process for the fast and efficient synthesis of diverse pyrroles.     

Efficient ZnCl2 assisted synthesis of calix[4]pyrroles catalysed by Brønsted acidic ionic liquids

A facile and efficient protocol is reported for the synthesis of calix[4]pyrroles and N-confused calix[4]pyrroles in moderate to excellent yields by one-pot condensation of ketones and pyrrole in the presence of catalytic amount of nontoxic acidic ionic liquids. In this reaction the products were obtained in short reaction time with selectivity of regular calix[4]pyrroles.     

Syntheses of calix[4]pyrroles by amberlyst-15 catalyzed cyclocondensations of pyrrole with selected ketones

A facile and efficient protocol is reported for the synthesis of calix[4]pyrroles and N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl or cycloalkyl ketones with pyrrole catalyzed by reusable Amberlyst(TM)-15 under eco-friendly conditions.     

Rh-catalyzed transannulation of N-tosyl-1,2,3-triazoles with terminal alkynes

The first transannulation of 1,2,3-triazoles with terminal alkynes into pyrroles is reported. The reaction proceeds in the presence of a Rh(2)(oct)(4)/AgOCOCF(3) binary catalyst system providing a straightforward approach to 1,2,4-trisubstituted pyrroles in good to excellent yields.     

A solvent and transition metal-free,highly efficient Brønsted acidic ionic liquid promoted one-potthree-component reactions for the synthesis of tetrasubstituted pyrroles

Abstract

The present protocol describes a highly efficient, transition metal and solvent-free one-pot annulation of amines, dialkyl acetylenedicarboxylates and β-nitrostyrene using imidazolium Brønsted acidic ionic liquid for the synthesis of tetrasubstituted pyrroles. A diverse functionalized tetrasubstituted pyrroles derivatives were obtained with excellent yields under transition metal and solvent-free conditions. The Brønsted acidic ionic liquid can be easily recovered and reused for the next reaction without any effects on the yields of the products. This green protocol provides structurally complex, medicinally important tetrasubstituted pyrroles with various substitution patterns in a one-pot operation.     

A new method for the synthesis of 2-phenylsulfonylaziridines via the reaction of α-halosulfonyl carbanion to imines

The reaction of lithio α-chloromethyl phenyl sulfone with imines gave aziridines in good yields. The resulting aziridines were alkylated and underwent the 1,3-dipolar cycloaddition with dimethylacetylene dicarboxylate to give pyrroles in excellent yields.     

Preparation of annulated nitrogen-containing heterocycles via a one-pot palladium-catalyzed alkylation/direct arylation sequence

[reaction: see text] A palladium-catalyzed/norbornene-mediated sequential coupling reaction involving an aromatic sp(2) C-H functionalization as the key step is described, in which an alkyl-aryl bond and an aryl-heteroaryl bond are formed in one pot. A variety of highly substituted six- and seven-membered annulated pyrroles and pyrazoles were synthesized in a one-step process in good yields from readily accessible N-bromoalkyl pyrroles or pyrazoles and aryl iodides.     

Triflic acid-catalyzed highly stereoselective friedel-crafts aminoalkylation of indoles and pyrroles

A simple and efficient synthesis to both enantiomers of highly enantiomerically enriched alpha-trifluoromethyl-alpha-(heteroaryl)-glycine derivatives via highly stereoselective aminoalkylation of indoles and pyrroles is described. The triflic acid-catalyzed reaction of enantiomeric 3,3,3-trifluoro-pyruvate-alpha-methylbenzyl imines with indoles and pyrroles and the subsequent Pd-catalyzed hydrogenolysis of the methylbenzyl group provided the products in high yields and excellent enantioselectivities.     

Simple synthesis of substituted pyrroles

Simple synthesis of substituted pyrroles using iodine-catalyzed and montmorillonite KSF-clay-induced modified Paal-Knorr methods has been accomplished with excellent yields. N-Substituted carbazole has also been prepared by following this method. If one of the reactants is a liquid, the reaction proceeds exceedingly well without a solvent. This method gives pyrroles with less nucleophilic multicyclic aromatic amines at room temperature.     

A convenient synthesis of pyrroles catalyzed by acidic resin under solvent-free condition

<正>A convenient and effective Paal-Knorr condensations of 2,5-hexanedione with most amines have been carried out at room temperature under solvent-free condition.Macroporous strongly acidic styrol resin(D001) as a novel,efficient,cost-effective,and reusable solid acid catalyst for the synthesis of pyrroles under the same conditions.The pyrroles were obtained in high yields in short reaction times.     

An efficient and convenient synthesis of pentasubstituted pyrroles from alkyl acetoacetates,dialkyl acetylenedicarboxylates,and amines

A simple and efficient synthesis of pentasubstituted pyrroles has been developed using a one-pot, two-step reaction. The synthesis of a series of 4-hydroxypenta-1,3-diene-tricarboxylates from alkyl acetoacetates and dialkyl acetylenedicarboxylates in the presence of K₂CO₃, followed by cyclization with amines, gave the corresponding pyrroles in excellent yields.     

Reaction of allenyl esters with sodium azide: an efficient synthesis of e-vinyl azides and polysubstituted pyrroles

The nucleophilic addition of sodium azide to 1,2-allenyl esters can generate vinyl azides in excellent yields with excellent regio- and stereoselectivities. Moreover, pyrroles are synthesized using 1-allyllic 1,2-allenyl esters as substrates in t-BuOH at 65 degrees C. The sequential reaction for pyrroles is developed on the basis of a novel domino process involving nucleophilic addition, cycloaddition, denitrogenation, and aromatization.     

Synthesis of N-Substituted Pyrroles Under Catalyst- and Solvent-Free Conditions

N-Substituted pyrroles were synthesized under neat conditions by the reaction of aromatic amines with 2, 5-dimethoxytetrahydrofuran in excellent yields.     

Palladium and copper cocatalyzed tandem N-H/C-H Bond functionalization: synthesis of CF3-containing indolo- and pyrrolo[2,1-a]isoquinolines

A palladium- and copper-catalyzed tandem N-H/C-H bond functionalization reaction of ortho-(2-chlorovinyl)bromobenzenes with indoles and pyrroles has been developed. A variety of CF(3)-containing indolo- and pyrrolo[2,1-a]isoquinolines were prepared in moderate to good yields via the cyclization of 1-bromo-2-(2-chloro-3,3,3-trifluoroprop-1-enyl)benzenes with indoles and pyrroles.     

Tandem Synthesis of Tetrasubstituted NH Pyrroles from Simple Nitriles

An efficient tandem route to obtain tetrasubstituted NH pyrroles in a one-pot manner has been developed, staring from simple nitriles, ethyl bromoacetates, and zinc. This reaction involves oxidative dimerization of the zinc bromide complex of β-enaminoesters using cerium ammonium nitrate (CAN) as an oxidant, affording 2,3,4,5-tetrasubstituted pyrroles in yields up to 91%.     

Bismuth Trichloride–Catalyzed C‐Alkylation of Pyrroles with Electron‐Deficient Olefins

The BiCl₃‐catalyzed reaction of pyrroles with electron‐deficient olefins generated the corresponding Michael adducts in high yields.     

One‐Pot Synthesis of Fused Pyrroles through a Key Gold‐Catalysis‐Triggered Cascade

A two‐step, one‐pot synthesis of fused pyrroles is realized by firstly condensing an N‐alkynylhydroxammonium salt with a readily enolizable ketone under mild basic conditions and then subjecting the reaction mixture to a gold catalyst, which triggers a cascade reaction involving a facile initial [3.3]‐sigmatropic rearrangement of the gold‐catalysis product, that is, an N,O‐dialkenylhydroxamine. The reaction provides a facile access to polycyclic pyrroles in moderate to good yields.     

Synthesis of 1,2,3,5-substituted pyrroles from α-bromoacetophenones and 2-nitroethene-1,1-diamines

The simple synthesis of 1,2,3,5-substituted pyrroles from α-bromoacetophenones and 2-nitroethene-1,1-diamines in the presence of K₂CO₃ in DMF at 120 °C is described. A range of fused and non-fused polysubstituted pyrroles were prepared in high yields with short reaction times.     

Efficient and Mild Protocol for the Synthesis of 4(3)-Substituted 3(4)-Nitro-1H-pyrroles and 3-Substituted 4-Methyl-2-tosyl-1 H-pyrroles from Nitroolefins and Tosylmethyl Isocyanide in Ionic Liquids

A mild and convenient method for the synthesis of 4(3)‐substituted 3(4)‐nitro‐1H‐pyrroles and 3‐substituted 4‐methyl‐2‐tosyl‐1H‐pyrroles from nitroolefins and tosylmethyl isocyanide (TosMIC) in ionic liquid 1‐butyl‐3‐methylimidazolium bromide ([bmIm]Br) was developed. The reactions were performed at room temperature with KOH as base with good yields in a short time (about 2 h). Some tough conditions, such as absolutely anhydrous organic solvents, low temperature, hazardous and expensive strong base or organic base, were not needed. The yields of 4(3)‐substituted 3(4)‐nitro‐1H‐pyrroles were moderate, but excellent yields were achieved for the preparation of 3‐substituted 4‐methyl‐2‐tosyl‐1H‐pyrroles. This strategy was quite general and it worked in a broad range of nitroolefins with aromatic, aliphatic or heterocyclic substituents. The recovered ionic liquid could be reused as solvent for several times without significant decrease of reaction yields.