Pyrrolidine Derivatives Research Articles

Cobalt-Catalyzed Intramolecular Reactions between a Vinylcyclopropane and an Alkyne: Switchable [5+2] Cycloaddition and Homo-Ene Pathways.

Cobalt-diphosphine catalysts have been found to promote intramolecular reactions between a vinylcyclopropane and an alkyne to selectively afford either the [5+2] cycloaddition product or the homo-ene reaction product under solvent control. The former product is exclusively formed in noncoordinating 1,2-dichloroethane, whereas the latter is dominant in coordinating solvents, such as acetonitrile and dimethylacetamide. Furthermore, a highly enantioselective variant of the homo-ene reaction afforded chiral tetrahydrofuran, pyrrolidine, and cyclopentane derivatives bearing 1,3-diene and alkylidene substituents.

Computational Insights into the Gold‐Catalyzed Ring‐Opening of Methylenecyclopropanes and Vinylcyclopropanes with Sulfonamides

AbstractComputational studies were carried out to investigate the mechanisms of gold‐catalyzed ring‐opening of methylenecyclopropanes (MCPs) and vinylcyclopropanes (VCPs), respectively, with sulfonamides to afford homoallylic amine intermediates, which would subsequently produce pyrrolidine derivatives. The detailed activation modes of MCPs mediated by the AuI catalyst were comprehensively explored. Computational results suggested that the activation of MCP by the AuI catalyst was less feasible. Instead, the AuI catalyst mediated activation of sulfonamides could result in the increased acidity of the N−H bond, which is ready to undergo intermolecular proton transfer to the C=C moiety of MCP to form a cyclopropylcarbinyl cation intermediate. Subsequently, the nucleophilic attack of the formed amido group to the three‐membered ring moiety of the yielded cyclopropylcarbinyl cation intermediate in an SN2 manner could follow to afford the ring‐opening homoallylic sulfonamide. In addition, computational studies indicated that such mechanistic pathway could also apply to the VCPs involved hydroamination with sulfonamides. The mechanism of triflic acid catalyzed hydroamination of MCPs and VCPs with sulfonamides also proceeds via the cyclopropylcarbinyl cation intermediates formed by the protonation of the alkene moiety of MCPs and VCPs, respectively. The ineffectiveness of amines as aminating reagents in the AuI‐catalyzed hydroamination of MCPs and VCPs was discussed.

Synthesis of Diastereomeric Pyrrolidine Sulfamides via Anchimerically Assisted Nucleophilic Substitution Reactions

The Mitsunobu reaction was employed in a key step during the development of a convenient synthetic route for the enantioselective preparation of pyrrolidine-sulfamide ligands from (R)- or (S)- [(S)-1-benzylpyrrolidin-2-yl](phenyl)methanol, and employing tert-butyl pyrrolidin-1-yl-sulfonylcarbamate as a non-conventional nucleophilic source. Although it is well documented that the exposure of this type of diastereomeric amino alcohols to the above-mentioned nucleophile usually leads to the formation of piperidines via ring expansion, either through classical nucleophilic substitution or the Mitsunobu version, only the pyrrolidine derivatives were generated with retention of configuration on the exocyclic stereocenter, owing to the neighboring group participation (internal backside nucleophilic substitution, SNib). Final removal of the N-Boc protecting group from the sulfamide fragment afforded chiral compounds with significant potential as chiral ligands in asymmetric catalysis. Keywords: Chiral pyrrolidine sulfamides, internal backside nucleophilic substitution, Mitsunobu reaction, neighboring group participation, prolinol derivatives, alcohol.

Aerobic intramolecular aminothiocyanation of unactivated alkenes promoted by in situ generated iodine thiocyanate

Aerobic intramolecular aminothiocyanation of unactivated alkenes has been developed by in situ generated iodine thiocyanate under open-flask conditions. This protocol provides a concise and efficient method for synthesizing SCN-containing pyrrolidine, piperidine and indoline derivatives with isolated yields of up to 87%. Furthermore, mixing iodine and sodium thiocyanate with oxygen afforded iodine thiocyanate (ISCN) and dithiocyanatoiodate [I(SCN)2]- which were testified by liquid chromatography mass spectrometry. A mechanistic investigation indicates that iodonium ion and sulfonium ion intermediates might be involved in this transformation.

Induction of cell killing and autophagy by amphiphilic pyrrolidine derivatives on human pancreatic cancer cells

We have synthesized a wide array of structurally related amphiphilic compounds, containing a functionalized pyrrolidine polar group coupled to different ether-linked hydrocarbon chains, to generate novel structures with antitumor activity. These newly synthesized amphiphilic pyrrolidine-derived compounds were classified in three different sub-libraries regarding the number of hydroxyl groups substituting the pyrrolidine moiety at C3 and C4. Pyrrolidine compounds with one or none hydroxyl groups showed a potent cell killing activity against pancreatic cancer cells, but they lacked selectivity for tumor cells. Pyrrolidine compounds with two hydroxyl groups induced cell death in a wide variety of pancreatic cancer cell lines, and they were somewhat less cytotoxic to normal non-tumor cells. Among these latter compounds, the diol-derived pyrrolidine 20 ((2R,3R,4S)-2-{(9Z)-hexadec-9-en-1-yloxy]methyl}pyrrolidine-3,4-diol) induced autophagy and a potent apoptotic response in pancreatic ductal adenocarcinoma cells, which was inhibited by Bcl-XL overexpression and by caspase inhibition, in a way similar to that of the amphiphilic ether lipid edelfosine, with which it was compared. Pharmacological and genetic inhibition of autophagy potentiated 20-mediated apoptosis. These structure-activity relationship studies point out the importance of the diol polar group and aliphatic side chain of 20 in promoting apoptosis against pancreatic cancer cells in a rather controlled way, and some additional subtle modifications were found to be potential modulators of the cytotoxic activity.

Synthesis, antimicrobial activity and acid dissociation constants of methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives

In this study, a series of polysubstituted methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives were designed and synthesized by the cyclization reaction of methyl 1-(benzoylcarbamothioyl)-5,5-diphenylpyrrolidine-2-carboxylates and 2-bromo-1-(4-substituted phenyl)ethanones in 70–96% yield. The starting pyrrolidine derivatives were synthesized via a 1,3-dipolar cycloaddition reaction in 83–88% yield. The stereochemistry of one of these methyl 5,5-diphenyl-1-(thiazol-2-yl)pyrrolidine-2-carboxylate derivatives was characterized by a single crystal X-ray diffraction study and the acid dissociation constants of these compounds were determined. An antimicrobial screening was performed against different bacterial and fungal strains and against the M. tuberculosis H37Rv strain. Interesting antibacterial activity was observed for two compounds against the A. baumannii strain with MIC values of 31.25 µg/mL (Ampicillin: 125 µg/mL) and against the M. tuberculosis H37Rv strain with MIC values of 0.98–1.96 µg/mL (Isoniazid: 0.98 µg/mL, Ethambutol: 1.96 µg/mL). Therefore, these structures can be considered as good starting points for the development of new powerful antimycobacterial agents.

(R)-DM-SEGPHOS-Ag(I)-Catalyzed Enantioselective Synthesis of Pyrrolidines and Pyrrolizidines via (1,3)- and Double (1,3)-Dipolar Cycloaddition Reactions.

An efficient diastereo- and enantioselective route to access a wide range of highly substituted pyrrolidine and pyrrolizidine derivatives has been described via (1,3)- and double (1,3)-dipolar cycloaddition reactions catalyzed by the (R)-DM-SEGPHOS-Ag(I) complex. The reactions proceed smoothly at ambient temperature, affording a variety of pyrrolidines and pyrrolizidines in high yields (up to 93%) with up to 99:1 dr and excellent enantioselectivities (up to 98% ee) without any additives. The newly synthesized pyrrolidine and pyrrolizidine derivatives contain four and seven contiguous stereogenic centers, respectively. Moreover, the synthetic utility of enantioenriched products has been demonstrated by transforming them into various synthetically useful advanced intermediates.

Stereodivergent Synthesis of α,α-Disubstituted α-Amino Acids via Synergistic Cu/Ir Catalysis.

Cu/Ir dual catalysis has been developed for the stereodivergent α-allylation of aldimine esters. The method enables the preparation of a series of nonproteinogenic α-amino acids (α-AAs) bearing two contiguous stereogenic centers in high yield with excellent stereoselectivity. All four product stereoisomers could be obtained from the same set of starting materials via pairwise combination of two chiral catalysts. Notably, one-pot protocol could be successfully applied for the preparation of the bimetallic Cu/Ir complexes to simplify the manipulation of Cu/Ir dual catalysis. This method could be further utilized for the construction of the key intermediate of a bioactive pyrrolidine derivative and the concise synthesis of a plant growth regulator (2S,3S)-2-amino-3-cyclopropylbutanoic acid.

Synthesis and biological evaluation of 4-amino-5-cinnamoylthiazoles as chalcone-like anticancer agents

A series of 4-amino-5-cinnamoylthiazoles 3a-p were designed and synthesized as chalcone-like anticancer agents. The synthesized derivatives 3a-p were evaluated for their in vitro antiproliferative activities against three different human cancer cell lines including MCF-7, HepG2 and SW480. Most of compounds could significantly prevent proliferation of tested cell lines. In particular, the pyrrolidine derivative 3e namely (E)-1-(4-amino-2-(pyrrolidin-1-yl)thiazol-5-yl)-3-(2,4-dichlorophenyl)prop-2-en-1-one showed promising activity, especially against HepG2 cells (IC50 = 10.6 μg/ml). Flow cytometric analyses revealed that the prototype compound 3e can prevent the proliferation of HepG2 cells by blockade of the cell cycle at the G2 phase and induction of apoptosis.

Design, Synthesis and Cytotoxic Activity of Spiro(oxindole-3-3'- pyrrolidine) Derivatives

Background: Spiro[pyrrolidine-3,3'-oxindole] compounds are reported to be highly bioactive natural and synthetic products. Initially, spirooxindole alkaloids were isolated from plants of the Apocynaceae and Rubiaceae families, which were found to have a common scaffold, spiro[pyrrolidine-3,3'-oxindole], exhibiting anticancer activities., we specifically aimed at the synthesis, characterization and anticancer activity of novel spiro[pyrrolidine-3,3' -oxindole] derivatives, compounds 6a-c and 7. Methods: The synthesis was initiated by Knovenegal condensation of indole-2-one with an appropriate benzaldehyde in presence of piperidine to afford compounds 3a-c. Compounds 6a-c were synthesized by an asymmetric 1,3-dipolar cycloaddition between compounds 3a-c and (2S, 3R)-2, 3, 5, 6-tetrahydro-2, 3-diphenyl-1, 4-oxazin-6-one, which is an intermediate compound formed by the Schiff base reaction between 3-methyl-butanal and (2S, 3R)-2, 3, 5, 6-tetrahydro-2, 3-diphenyl- 1,4-oxazin-6-one, in presence of molecular sieves (4Å) under argon atmosphere. Compound 6a was then reacted with ethylamine-HCl in THF at room temperature to yield compound 7. Results: Cytotoxic effects of the compounds synthesized were determined on Huh7, MV, HCT116 and MCF7 cancer cell lines by the NCI-60 Sulforhodamine B Assay, using (S)-(+)-Camptothecin as a positive control. In general, target compounds showed better cytotoxic activities against the MCF7 and HCT116 cancer cell lines. It was found that compound 7 exhibited the most potent inhibitory activity with IC50 values of 4.8 µM, 3.9 µM, 14.9 µM and 8.2 µM against the MCF7, HCT116, MV and Huh7 cell lines, respectively. Conclusion: It was determined that compounds 6a&6b possess C6'(S)|C8'(R)|C9'(R) stereochemistry and compound 7 adopts C2'(S)|C4'(R)|C5'(R) stereochemistry. Cytotoxicity studies suggest that compound 7 gave rise to the highest anticancer activity against MCF7, HCT116, and Huh7 cancer cell lines.

Catalytic asymmetric synthesis of pyrrolidine derivatives bearing heteroatom-substituted quaternary stereocenters

An enantioselective [3 + 2] cycloaddition of heteroatom-substituted alkenes with α-substituted isocyanoacetates has been developed. Excellent reactivity and enantioselectivity were obtained.

Reactions of 1-[(dimethylamino)methyl]naphthalen-2-ols with cyclic push-pull nitroenamines

A method was developed for the synthesis of 1-[2-nitro-2-(pyrrolidin-2-ylidene)ethyl]- and 1-[2-(imidazolidin-2-ylidene)-2-nitroethyl]-naphthalen-2-ols based on a reaction of 1,2-naphthoquinone-1-methide precursors with heterocyclic β-nitroenamines (pyrrolidine and imidazolidine derivatives).

Synthesis of Highly Functionalized Pyrrolidine Derivatives from Easily Accessible Diethyl (E)‐4‐Oxohex‐2‐enedioate

The diastereoselective synthesis of highly substituted pyrrolidines has been accomplished using a six‐carbon building block bearing carbon atoms with different reactivities. In this reaction, the building block acts a 1,3‐dipole and undergoes cyclization with imines formed in situ to give pyrrolidine derivatives.

Nitroxides as Antioxidants and Anticancer Drugs.

Nitroxides are stable free radicals that contain a nitroxyl group with an unpaired electron. In this paper, we present the properties and application of nitroxides as antioxidants and anticancer drugs. The mostly used nitroxides in biology and medicine are a group of heterocyclic nitroxide derivatives of piperidine, pyrroline and pyrrolidine. The antioxidant action of nitroxides is associated with their redox cycle. Nitroxides, unlike other antioxidants, are characterized by a catalytic mechanism of action associated with a single electron oxidation and reduction reaction. In biological conditions, they mimic superoxide dismutase (SOD), modulate hemoprotein’s catalase-like activity, scavenge reactive free radicals, inhibit the Fenton and Haber-Weiss reactions and suppress the oxidation of biological materials (peptides, proteins, lipids, etc.). The use of nitroxides as antioxidants against oxidative stress induced by anticancer drugs has also been investigated. The application of nitroxides and their derivatives as anticancer drugs is discussed in the contexts of breast, hepatic, lung, ovarian, lymphatic and thyroid cancers under in vivo and in vitro experiments. In this article, we focus on new natural spin-labelled derivatives such as camptothecin, rotenone, combretastatin, podophyllotoxin and others. The applications of nitroxides in the aging process, cardiovascular disease and pathological conditions were also discussed.

Visible-Light-Mediated Annulation of Electron-Rich Alkenes and Nitrogen-Centered Radicals from N-Sulfonylallylamines: Construction of Chloromethylated Pyrrolidine Derivatives.

A visible-light-mediated annulation of N-sulfonylallylamines and olefins is reported. Rapid access to highly functionalized chloromethylated pyrrolidines can be achieved using mild conditions for the generation of nitrogen-centered radicals. Both a transition-metal-based catalyst and an organic dye can be used as photosensitizers with 0.5 mol % loading. The reaction was found to be applicable to a large variety of electron-rich and electron-neutral olefins.

Hydroxy-Assisted Regio- and Stereoselective Synthesis of Functionalized 4-Methylenepyrrolidine Derivatives via Phosphine-Catalyzed [3 + 2] Cycloaddition of Allenoates with o-Hydroxyaryl Azomethine Ylides.

In this work, we present a new strategy for the chemo-, regio-, and stereoselective synthesis of functionalized pyrrolidine derivatives via a hydroxy-assisted phosphine-catalyzed reaction of allenoates or substituted allenoates with o-hydroxyaryl azomethine ylides that offers a wide variety of 4-methylenepyrrolidine derivatives in synthetically useful yields with high stereoselctivities under mild conditions. Remarkably, it is the first example of highly regio- and stereoselective phosphine-catalyzed [3 + 2] cycloaddition of allenoates with o-hydroxyaryl azomethine ylides.

Enantioselective Synthesis of Alkylthioetherpyrrolidine Derivatives via [3+2] Cycloaddition of α-Thioacrylates with Isocyanoacetates.

An unprecedented catalytic asymmetric method for the [3+2] cycloaddition of isocyanoacetates with α-thioacrylates/α-phthalimidoacrylates has been developed with excellent enantioselectivities. The generated pyrrolines could be readily further reduced to an array of structurally various and biologically important pyrrolidine derivatives. α-Tosyloxyacrylate with isocyanoacetates as well as tosylmethylisocyanide could be used to produce 2,4-disubstituted pyrroles.

In silico screening for identification of pyrrolidine derivatives dipeptidyl peptidase-IV inhibitors using COMFA, CoMSIA, HQSAR and docking studies

To explore the relationship between the structures of substituted pyrrolidine derivatives and their inhibition of dipeptidyl peptidase IV inhibitors. The QSAR, including CoMFA, CoMSIA and HQSAR, were applied to identify the key structures impacting their inhibitory potencies. The CoMFA, CoMSIA and HQSAR with cross-validated correlation coefficient (q2) value of 0.727, 0.870 and 0.939 and r2 value of 0.973, 0.981 and 0.949. Based on the structure-activity relationship revealed by the present study, we have designed a set of novel dipeptidyl peptidase IV inhibitors that showed excellent potencies in the developed models. Thus, our results allowed us to design new derivatives with desired activities.

Polygodial: A viable natural product scaffold for the rapid synthesis of novel polycyclic pyrrole and pyrrolidine derivatives

The dialdehyde polygodial was utilised as a chiral scaffold for the unified synthesis of novel polycyclic pyrrole and pyrrolidine derivatives. Mechanistic insight into the reaction of primary amines with this dialdehyde was obtained. In addition, one of these polycyclic pyrroles was transformed further to prepare novel pentacyclic frameworks.

Lewis Acid Catalyzed Formal [3+2] Cycloaddition of Donor‐Acceptor Cyclopropanes and 1‐Azadienes: Synthesis of Imine Functionalized Cyclopentanes and Pyrrolidine Derivatives

AbstractLewis acid catalyzed formal [3+2] cycloadditions of 1‐azadienes with donor acceptor cyclopropanes to synthesize varieties of imine functionalized cyclopentanes and pyrrolidine derivatives in moderate to high yield have been developed. Moreover, pharmaceutically relevant azabicyclo[3.2.1]octane, bearing two all‐carbon quaternary stereogenic centers at the bridgehead positions, has been synthesized by nosyl group deprotection and intramolecular amidation of imine functionalized cyclopentane derivative.magnified image