Pyrrole Series Research Articles

Production of alkane and cyclohexane derivatives with two heterocyclic substituents of the furan, pyrrole, and thiophene series

Heating 1,2,11,12-tetrachloro-2,11-bis(R-4,9-dodecanediones) and 1,4-bis(3-R-3,4-dichlorobutanoyl)cyclohexanes gave, respectively, 1,4-difuryl derivatives of butane and cyclohexane, while treatment of them with primary amines or phosphorus pentasulfide in DMF was used to synthesize dipyrryl and dithienyl compounds. 1-R-3-R1-3,4-Dichlorobutanones react with ethylenediamine in aqueous alkali solutions to give 1,2-dipyrryl or monopyrryl derivatives of ethane.

Lactam and acid amide acetals. 64. Acylation of enamino ketones of the indolin-3-one and 2-pyrrolin-4-one series and synthesis of 2-indolyl- and 5-pyrrolylacrylic acid derivatives

The reaction of 2-(N,N-dimethylaminomethylene)indolin-3-one and 2-methyl-3-ethoxycarbonyl-5-(N,N-dimethyl aminomethylene)-2-pyrrolin-4-one with acyl halides was used to synthesize immonium salts, the aqueous hydrolysis of which leads to 2-formyl-3-hydroxyindole and 4-hydroxy-5 formylpyrrole derivatives. α-Cyano-Β-(2-indolyl)- and α-cyano-Β-(5-pyrrolyl)acrylic acid derivatives were synthesized by reaction of immonium salts of the pyrrole series, 4 acyloxy-5-formylpyrrole and 2-formyl-3-acyloxyindole derivatives, with compounds that contain an active methylene group.

4916246 Paramagnetic chelates useful for NMR imaging

CB2-based therapeutics show strong potential in the treatment of diverse diseases such as inflammation, multiple sclerosis, pain, immune-related disorders, osteoporosis and cancer, without eliciting the typical neurobehavioral side effects of CB1 ligands. For this reason, research activities are currently directed towards the development of CB2 selective ligands. Herein, the synthesis of novel heterocyclic-based CB2 selective compounds is reported. A set of 2,5-dialkyl-1-phenyl-1H-pyrrole-3-carboxamides, 5-subtituted-2-(acylamino)/(2-sulphonylamino)-thiophene-3-carboxylates and 2-(acylamino)/(2-sulphonylamino)-tetrahydrobenzo[b]thiophene-3-carboxylates were synthesized. Biological results revealed compounds with remarkably high CB2 binding affinity and CB2/CB1 subtype selectivity. Compound 19a and 19b from the pyrrole series exhibited the highest CB2 receptor affinity (Ki = 7.59 and 6.15 nM, respectively), as well as the highest CB2/CB1 subtype selectivity (∼70 and ∼200-fold, respectively). In addition, compound 6b from the tetrahydrobenzo[b]thiophene series presented the most potent and selective CB2 ligand in this series (Ki = 2.15 nM and CB2 subtype selectivity of almost 500-fold over CB1). Compound 6b showed a full agonism, while compounds 19a and 19b acted as inverse agonists when tested in an adenylate cyclase assay. The present findings thus pave the way to the design and optimization of heterocyclic-based scaffolds with lipophilic carboxamide and/or retroamide substituent that can be exploited as potential CB2 receptor activity modulators.

Synthesis and cyclic voltammetric behaviour of some 3-substituted thiophenes and pyrroles: Precursors for the preparation of conducting polymers

The syntheses are reported of a series of 3-substituted thiophenes and pyrroles bearing long-chain amide, polyether and acyl functionality. The alkoxy-thiophenes and α-ketopyrrole monomers are more easily oxidized than the alkyl-substituted thiophenes. Their anodic electrochemistry has been studied by cyclic voltammetry.

Acid properties of short-lived radicals and their appearance in photoinduced hydrogen atom transfer

1. The acid properties of short-lived radicals from the pyrrole, indole, benzazole, and benzoquinone series were studied by nanosecond laser spectroscopy in acetonitrile. 2. The linear dependence of the change in the standard free energy of formation of neutral radicals as a result of transfer of an H atom from the heterocyclic molecules to the quinone molecules and a change in the standard free energy of electron transfer in these systems was demonstrated. 3. The role of intermediate states with electron transfer in the process of photoinduced cleavage of the hydrogen atom was investigated. It was found that the efficiency of formation of products of atom transfer is determined by the acid-base properties of the components of the radical ion pairs (exiplexes).

ChemInform Abstract: Reactions at High Pressure. Part 15. Rates, Activation Parameters, and a Volume Profile for Retro‐Diels ‐ Alder Reactions in the Pyrrole Series

ChemInform Abstract: Reactions at High Pressure. Part 15. Rates, Activation Parameters, and a Volume Profile for Retro‐Diels ‐ Alder Reactions in the Pyrrole Series

Reactions at high pressure. Part 15. Rates, activation parameters, and a volume profile for retro-Diels–Alder reactions in the pyrrole series

Thermal decomposition of N-acylpyrrole adducts of N-phenylmaleimide by a [π2S+σ2S+σ2S] route occurs at temperatures below 70 °C. Rates and activation parameters for the thermolyses ot endo- and exo-10-benzoyl-4-phenyl-4,10-diazatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione (6) and (7), exo-10-acetyl-4-phenyl-4,10-diazatricyclo[5.2.1.02,6]dec-8-ene-3,5-dione (8), and endo-4-phenyl-4-aza-10-oxatricyclo[5.2.1.0]dec-8-ene-3,5-dione (9) have been measured at various temperatures and pressures and in various solvents. It is confirmed that the volume of activation for thermolysis of (6) is negative, consistent with a transition state more compact than either reagents or products and not accountable for in terms of dipolar character.

Polycondensed nitrogen heterocycles. Part 13. Pyrrolo[3,2‐b]indole by intramolecular nucleophilic substitution reaction in the pyrrole series

AbstractAn intramolecular nucleophilic substitution in the pyrrole series has been generalized. The behaviour of nitro, chlorine, bromine and iodine as leaving groups towards the nucleophilic amino group was observed. An acid catalyzed mechanism has been proposed.

Neighboring group participation in the pyrrole series

Neighboring group participation in the pyrrole series

1‐[(Dimethylamino)methyl]pyrrol aus Trimethyl (1‐pyrrolyl)‐ammonium‐Ion

1‐[(Dimethylamino)methyl]pyrrole from Trimethyl (1‐pyrrolyl)ammonium IonTrimethyl (1‐pyrrolyl)ammonium iodide (5a) and the corresponding p‐toluene‐sulfonate 5b are transformed by strong bases into 1‐[(dimethylamino)methyl]‐pyrrole (9), i.e. into a N‐Mannich base, a type of compound novel in the pyrrole series. In this reaction, which is very fast in DMSO, the cation of compounds 5 is deprotonated to form the nitrogen ylide 6. The latter undergoes a Stevens‐type rearrangement to 9. Several facts, namely the negative outcome of a cross‐reaction experiment with 3,4‐dimethylpyrrole and of an attempt to obtain 9 from pyrrole and dimethyl (methylidene)ammonium iodide in the presence of one equivalent of sodium methoxide, as well as unsuccessful CIDNP studies point to a rearrangement mechanism via the contact ion pair 12.

Contribution to the study of inductive effect transmission in pyrrole derivatives

Transmission of the inductive effect in pyrrole derivatives was investigated on 2-ethylpyrrole (VIa), 2-methylpyrrole (VIb), 2-dimethylaminomethylpyrrole (VIc), 2-hydroxymethylpyrrole (VId), methyl 2-pyrrolylacetate (VIe), 2-pyrrolylacetonitrile (VIf), 2-benzenesulfonylmethylpyrrole (VIg) and trimethyl(2-pyrrolylmethyl)ammonium iodide (VIh), by comparison of their relative basicities and acidities. These were determined by IR spectroscopy from the strength of donor-acceptor interactions of the pyrrole derivatives with suitable standard compounds. The found differences show good linear correlations with the σI substituent constants. On this basis, the transfer of the inductive effect in the given pyrrole series appears to be proportional.

Polycondensed nitrogen heterocycles. Part 8. Pyrrolo[3,2-b]indole

The reduction of the nitro-derivatives (4a–c) with iron–acetic acid leads to the pyrrolo[3,2-b]indoles (7a–c). This unusual indolization, in which displacement of the heterocycle amino-group occurs, is regarded as a nucleophilic attack by the 2-aminophenyl group on the pyrrole ring, and is an interesting example of intramolecular nucleophilic substitution in the pyrrole series.

INDO MO calculations of the electronic structures of pyrolle, imidazole, and derivatives

INDO MO calculations on a series of N-substituted pyrroles and imidazoles have been analysed for substituent effects. Some of the basic characteristics of the σ I and σ R 0 parameters are reflected in the calculated electron densities of the compounds studied. For example, good correlations are obtained between Δ qσ N(1)/ΣΔ qσ parameters and σ I for the R substituted compounds, as well as between ΣΔ qπ values and σ R 0 for the + R derivatives. The + R substituents lead to an increased localization of the π-bonds, whereas R substituted derivatives show an increased delocalization, i.e., the π-bond orders across C(2)C(3) [or C(2)N(3)] and C(4)C(5) decrease and those across other bonds in the ring increase.

Keto acids in the pyrrole series

The spectral properties of o-(2-pyrrolylketo)benzoic acid and its N-methyl and N-benzyl analogs were investigated in order to detect ring-chain tautomerism. It is shown that the investigated acids exist in the open keto form. The corresponding derivatives involving the carbonyl group were obtained. The preparation of derivatives of the cyclic lactol form of the 2-pyrrolylketobenzoic acids is described.

Strong base-catalyzed thermal rearrangements of azines of benzyl alkyl ketones

Azines of benzyl alkyl ketones undergo cyclization in the presence of strong basic catalysts to give mixtures of compounds of the pyrrole and pyrazole series. The formation of pyrazole products probably proceeds via the scheme of the Fischer reaction taking into account the concept of a [3,3] sigmatropic shift. However, the presence of nitriles and hydrocarbons among the products of the reaction of pyrazole derivatives indicates the ambiguous character of the proposed scheme. The rearrangement of azines to pyrazole compounds probably proceeds through a step involving the formation of a carbanion, while the formation of nitriles and hydrocarbons can be explained by radical processes. The dependence of the ratio of the pyrolysis products (pyrrole/pyrazole) on the amount of catalyst and its basicity (LiH, NaH, KH, NaOH, KOH, PhOK, and CH3OK) makes it possible to assume that the occurrence of the reaction through a step involving a [3,3] shift is realized thermally and that small amounts of the catalyst promote the realization of this reaction pathway; however, a high percentage of the catalyst and the use of the most basic catalysts lead to an increase in the yields of the pyrazole products.

Studies in Pyrrole Series

Studies in Pyrrole Series

抗炎症性化合物の合成(第1報)フェニル置換ピロール誘導体の合成と抗炎症性作用

A series of phenyl-substituted pyrroles were prepared by various methods and their anti-inflammatory activity and toxicity wereexamined. As the results, it was found that 2-alkyl-4, 5-diarylpyrrole, especially bimetopyrol[2-methyl-4, 5-bis(p-methoxyphenyl)pyrrole](III-2) had the most potent activity.

Crystallographic studies in the pyrrole series. Part I. Crystal and molecular structure of ethyl 4-acetyl-3-ethyl-5-methylpyrrole-2-carboxylate

Crystals of the title compound are monoclinic, space group P21/n, Z= 4, with cell dimensions a= 6·772(3), b= 14·628(5), c= 12·187(5)A, and β= 94·20(12)°. The structure was solved by direct methods, and refined by least-squares to R 0·0615 for the 1531 statistically significant reflections measured. The geometry of the molecule is compared with that observed for the pyrrole ring in other systems; in particular it has been observed that the normal symmetrical bonding arrangement in the ring is here considerably perturbed, owing to the electronic effects of the substituents.

Cycloadditions in the pyrrole series

Cycloadditions in the pyrrole series

The pyrolysis of some anhydrides of the pyrrole series

The pyrolysis of some anhydrides of the pyrrole series