Gadolinium triflate catalyzed alkylation of pyrroles: efficient synthesis of 3-oxo-2,3-dihydro-1H-pyrrolizine derivatives

Novel 2-alkylated pyrrole derivatives were synthesized regioselectively by Gd(OTf)₃ catalyzed addition reactions of pyrrole to substituted dimethyl 2-benzylidenemalonate derivatives under mild reaction conditions. 2-Alkylated pyrrole derivatives are used for the construction of the 3-oxo pyrrolizine skeleton. Intramolecular cyclization of alkylated pyrrole derivatives afforded new diastereoselective 3-oxo-2,3-dihydro-1H-pyrrolizine derivatives with good to high yields.     

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives

One-pot synthesis of 5-amino 4-cyano pyrrole derivatives is herein disclosed. The described method consists of four steps and gives new pyrrole derivatives in moderate to good yields. This synthesis can be used for a large scale preparation.     

Short,Efficient Syntheses of Pyrrole α-Amides

We report an inexpensive method for producing a diverse array of pyrrole amides on a large scale and in good yield. The synthetic sequence allows for the preparation of a number of pyrrole amide derivatives in excellent to moderate yields from commercially available compounds. The diketene adduct, in the presence of an amine nucleophile, provides an excellent method for acetoacetylation. For diversity and versatility, a second method utilizing Meldrum's acid was successfully employed for the preparation of additional acetoacetamide derivatives. Using the Knorr pyrrole synthesis, pyrrole amides were readily prepared from the oxime of the acetoacetamides.     

Selective synthesis of N-substituted pyrrolo[1,2-a]pyrazin-1(2H)-one derivatives via alkyne cyclization

A novel and efficient synthesis of N-substituted pyrrolo-pyrazinone derivatives has been developed. A trichloroacetyl group connected to the pyrrole ring was converted into the desired carboxamide derivatives. Promoted by NaH, the pyrrole carboxamide derivatives underwent a tandem reaction with propargyl bromide to afford pyrrolo-pyrazinones with high efficiency under very mild conditions. The mechanism for the formation of the products is discussed and supported by DFT calculations.     

Pyrrole Oximes: Synthesis, Reactions, and Biological Activity. (Review)

Data on the production methods and reactions of pyrrole aldoximes and ketoximes and their derivatives are reviewed. The synthesis of new heterocycles from the pyrrole oximes is examined separately. The principal results from investigation of the biological activity of pyrrole oximes are described.     

Highly Efficiently Synthesis of Disubstituted Pyrrole Derivatives via Rh(III)-Catalyzed Direct C–H Alkylation Under Mild Conditions

A mild and highly efficient Rh(III)-catalyzed direct C–H alkylation of pyrroles with diazo compounds has been developed. This green and atom-economic catalytic process enables an efficient access to various densely functionalized pyrrole derivatives in good to excellent yields, and it is potentially applicable to the large-scale synthesis of pyrrole derivatives.

     

First synthesis of tetrapyrrolylporphyrin

[reaction: see text] N-alkyl-substituted meso-tetrapyrrolylporphyrin (TPyrP) and its derivatives were synthesized for the first time via an acid-catalyzed condensation between N-alkyl-2,4-diformylpyrrole and unsubstituted pyrrole and a subsequent deformylation reaction. X-ray structural analysis of formyl-substituted TPyrP shows the tilting of meso pyrrole rings ca. 60 degrees to the porphyrin plane. Formyl groups of meso pyrrole rings were removed by treatment with trifluoroacetic acid (TFA) in pyrrole.     

Formation of insoluble perylenetetracarboxylic diimide films by electro- or photo-crosslinking of pyrrole units

Perylenetetracarboxylic diimide derivatives bearing 2- or 4-peripheral pyrrole pendants could be efficiently crosslinked to form an insoluble film either by electropolymerization or visible light induced oxidative photopolymerization of the pyrrole units.     

CH...anion interaction in BF2 complexes of C3-bridged oligopyrroles

Alkyl-substituted derivatives of 1,3-dipyrrolyl-1,3-propanedione BF2 complexes, the efficient receptors for halide and oxoanions with use of bridging CH as well as pyrrole NH, are reported. BF2 complexes with only one pyrrole NH interaction site (2d,e), which exhibit smaller affinities than the basic structure (2b), bind anions tightly, which is inferred by UV/vis absorption spectral changes, compared to the derivatives with an alkyl group at the bridging carbon (2f) or two pyrrole nitrogen sites (2c). With use of 1H NMR and theoretical studies for anion complexes of 2d and 2e, bridging CH (and one beta-CH in 2d) as well as pyrrole NH is found to interact with anions.     

An entry into hexahydro-2H-thieno[2,3-c]pyrrole 1,1-dioxide derivatives

Hexahydro-2H-thieno[2,3-c]pyrrole is proposed as a low molecular weight polar scaffold to construct compound libraries used in the search for new drugs. Practical syntheses of derivatives of this bicyclic scaffold were developed, based on [3 + 2] cycloaddition of the ylide generated from N-benzyl-1-methoxy-N-((trimethylsilyl)methyl)methanamine and 4-substituted 2,3-dihydrothiophene 1,1-dioxides. All of the 3-substituted hexahydro-2H-thieno[2,3-c]pyrrole 1,1-dioxide derivatives were obtained as single diastereomers. Conformational properties of the hexahydro-2H-thieno[2,3-c]pyrrole 1,1-dioxide derivatives were explored using X-ray diffraction studies. The potential of the scaffold to generate libraries of 3D-shaped molecules was demonstrated.     

Synthesis of N‐Aryl Formyl Pyrrole from γ‐Lactam Derivatives: A Highlight

Pyrrole containing analogs are considered as a potential source of biologically active compounds and have significant set of advantageous properties and are found in many natural products. A number of methods have been reported till now to synthesize pyrrole and pyrrole containing analogs. This review article outlines highlight the recent progresses in pyrrole synthesis from γ‐lactam derivatives.     

Cyclization reactions of homopropargyl azide derivatives catalyzed by PtCl4 in ethanol solution: synthesis of functionalized pyrrole derivatives

[Structure: see text] PtCl4-catalyzed cyclization reactions of homopropargyl azide derivatives to pyrrole rings were investigated. Using ethanol as solvent with 2,6-di-tert-butyl-4-methylpyridine as the base was found to be the best set of conditions for effecting this ring-closing reaction. These reaction conditions can be applied to the preparation of functionalized pyrrole derivatives, with no effect on the functional groups.     

Palladium-catalyzed C-H arylation of 2,5-substituted pyrroles

The palladium-catalyzed direct arylation of 2,5-substituted pyrrole derivatives with diaryliodonium salts to generate tri-, tetra-, and penta-substituted pyrrole products is described. The scope and limitations of these transformations are also reported.     

Preparation of pyrrole and pyrrolidine derivatives of pyrimidine. 1‐(2‐pyrimidinyl)pyrrole ‐ an inhibitor of X. phaseoli and X. malvacearum

Pyrrole and pyrrolidine derivatives of pyrimidine were prepared in which the nitrogen atom of the pyrrole or pyrrolidine ring is bonded directly to the 2‐ or 4‐carbon atom of the pyrimidine ring. Pyrrole derivatives were prepared by the dry distillation of an intimate mixture of an aminopyrimidine with mucic acid and by the reaction of a chloropyrimidine with potassium pyrrole. Pyrrolidine derivatives were prepared by the reaction of a chloropyrimidine with pyrrolidine and, in a single instance, by the catalytic hydrogenation of a pyrimidinylpyrrole. At a concentration of 200 mcg/mL, 1‐(2‐pyrimidinyl)pyrrole inhibited two plant pathogenic bacteria — Xanthomanus phaseoli (pathogenic on the bean plant) and Xanthomanus malvacearum (pathogenic on the cotton plant).     

Yb（OTf）3 Catalyzed Nucleophilic Conjugate Addition of Pyrrole to α，β-Unsaturated Ketones and Nitro-compounds

Under the catalysis of Yb(OTf)3, nucleophilic conjugate addition of pyrrole to electron deficient olefins in CH2Cl2 at ambient temperature gives corresponding 2-alkylated pyrrole derivatives in good yields with high selectivity.     

Skeletal Diversity in Catalytic Synthesis of (1,3-Oxazacycloalk-3-ylmethyl)-Substituted Pyrroles

Russian Journal of General Chemistry - A series of bi- and trinuclear pyrrole derivatives was prepared by the 5 mol % ZrOCl2 ·8H2O-catalyzed CH-sp2-aminomethylation reaction of pyrrole with...     

Supramolecular Interaction of Keto-substituted Pyrroles

Several types of pyrrole derivatives bearing carbonyl groups were synthesized and their structures in the solid states were elucidated by single crystal X-ray analysis. In the case of α-ketopyrroles, the molecules exist as hydrogen bonding dimers between the pyrrole NH and carbonyl groups, while in the case of β-ketopyrrole derivatives, hydrogen bonding networks are formed. Both the α,β′-diketo-substituted pyrroles and their derivatives are suggested to be suitable for the construction of 1-D chain networks. Overall, the effects of substituents on the supramolecular interactions are discussed in detail.     

Thermolysis of 1-dialkylaminoanthraquinones — New method for the synthesis of anthra[1, 9-bc]pyrrole derivatives

1-Dialkylaminoanthraquinones undergo cyclization to give anthra[1,9-bc]pyrrole derivatives on thermolysis in pyridine and other polar solvents. The cyclization proceeds through intramolecular rearrangement of 1-dialkylaminoanthraquinones to anthra[1,9-de]-1,3-oxazine derivatives and through subsequent contraction of the 1,3-oxazine ring to a pyrrole ring.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1360–1363, October, 1975.     

The application of vinylogous iminium salt derivatives to efficient formal syntheses of the marine alkaloids lamellarin G trimethyl ether and ningalin B

Studies directed at the synthesis of lamellarin G trimethyl ether and ningalin B via vinylogous iminium salt derivatives are described. The successful strategy relies on the formation of a 2,4-disubstituted pyrrole or a 1,2,3,4-tetrasubstituted pyrrole from a vinylogous iminium salt or vinylogous iminium salt derivative. Subsequent transformations of these highly substituted pyrroles lead to efficient and regiocontrolled formal syntheses of the respective pyrrole containing natural products.     

Synthesis of pyrrole and indole quinoxalinone and oxazinone derivatives by intramolecular copper-catalyzed reactions

Intramolecular N-arylation of pyrrole and indole carboxamides and carboxylates linked with a pendant haloarene by Cu-catalyzed reactions to synthesize pyrrole and indole quinoxalinone and oxazinone derivatives is reported. The ring closure reactions were carried out by conventional heating and MW irradiation. The use of conventional heating affords moderate to good yields of the quinoxalinone and oxazinone derivatives (34-72%), while by using MW heating the best results are obtained (41-99%).