Cyclopentane Core Research Articles

Biosynthesis of the Non-canonical C17 Sesquiterpenoids Chlororaphen A and B from Pseudomonas chlororaphis.

Chlororaphens A and B are structurally unique non-canonical C17 sesquiterpenoids from Pseudomonas chlororaphis that are made by two SAM-dependent methyltransferases and a type I terpene synthase. This study addresses the mechanism of their formation in isotopic labelling experiments and DFT calculations. The results demonstrate an astonishing complexity with distribution of labellings within a cyclopentane core that is reversely connected to two acyclic fragments in chlororaphen A and B. In addition, the uptake of up to 14 deuterium atoms from D2O was observed. These findings are explainable by a repeated late stage multistep rearrangement sequence. The absolute configurations of the chlororaphens and their biosynthetic intermediates were elucidated in stereoselective labelling experiments.

Synthesis of the Cyclopentane Core Skeleton of Cranomycin and Jogyamycin.

Cranomycin and jogyamycin, two aminocyclopentitol natural products, possess complex structures and potential medicinal properties. This review describes synthetic studies about the process of making an advanced intermediate of cranomycin and jogyamycin. This highly functionalized intermediate, featuring three contiguous amine-substituted stereocenters, was constructed from cyclopentadiene through a series of reactions including the nitroso Diels-Alder reaction, nitrogen radical cyclization reaction, 1,2-nitrogen migration, and stereoselective nitrogen addition.

A concise and scalable chemoenzymatic synthesis of prostaglandins

Prostaglandins have garnered significant attention from synthetic chemists due to their exceptional biological activities. In this report, we present a concise chemoenzymatic synthesis method for several representative prostaglandins, achieved in 5 to 7 steps. Notably, the common intermediate bromohydrin, a radical equivalent of Corey lactone, is chemoenzymatically synthesized in only two steps, which allows us to complete the synthesis of prostaglandin F2α in five steps on a 10-gram scale. The chiral cyclopentane core is introduced with high enantioselectivity, while the lipid chains are sequentially incorporated through a cost-effective process involving bromohydrin formation, nickel-catalyzed cross-couplings, and Wittig reactions. This cost-efficient synthesis route for prostaglandins holds the potential to make prostaglandin-related drugs more affordable and facilitate easier access to their analogues.

Orthogonally Protected Diaminocyclopentenones as Synthons: Total Synthesis of (±)-Agelastatin A.

Natural products containing aminocyclopentanes are common secondary metabolites, often biologically active. This work aims at the preparation of a useful synthon for total synthesis containing orthogonally protected amines. To this end, furfural and two amines were employed to form mixed trans-4,5-diaminocyclopentenones promoted by Cu(OTf)2. The selected amines can be orthogonally deprotected, allowing selective modification of the amines on the cyclopentane core. Their utility was showcased for the total synthesis of highly complex (±)-Agelastatin A.

A General Catalyst Controlled Route to Prostaglandin F2α.

We report a general, catalyst-controlled route to prostaglandin F2α and its analogues. The approach uses a Rh-catalyzed dynamic kinetic asymmetric Suzuki-Miyaura coupling reaction between a racemic bicyclic allyl chloride and alkenyl boronic esters bearing chiral alcohols to give cyclopentyl intermediates bearing 3 contiguous stereocenters. The route provides advanced intermediates in 99% ee as a single diastereoisomer in all cases examined, with the absolute stereochemistry of the cyclopentane core controlled by the ligand. Intermediates that could be used to produce prostaglandin analogues such as bimatoprost, latanoprost, fluprostenol, and cloprostenol were synthesized. The final two stereocenters were installed via Pd-catalyzed Tsuji-Trost alkylation and iodolactonization. The synthesis of PG F2α was achieved in 19% yield in 16 longest linear steps.

Unified Total Synthesis of Diverse Meroterpenoids from Ganoderma Applanatum.

A unified approach to meroterpenoids applanatumols B, V, W, X, and Y produced by the medicinal fungus Ganoderma applanatum and 2'-epi-spiroapplanatumine O is presented. The key synthetic sequence consists of a tandem anionic ketone allylation/oxy-Cope rearrangement/α-oxygenation furnishing an α-aminoxy ketone and a persistent radical effect-based 5-exo-trig cyclization leading to the trisubstituted cyclopentane core. The relative configuration of applanatumol V has to be revised. Some compounds display significant cytotoxic and antioxidant properties.

Synthesis and evaluation of novel cyclopentane urea FPR2 agonists and their potential application in the treatment of cardiovascular inflammation.

The discovery of natural specialized pro-resolving mediators and their corresponding receptors, such as formyl peptide receptor 2 (FPR2), indicated that resolution of inflammation (RoI) is an active process which could be harnessed for innovative approaches to tame pathologies with underlying chronic inflammation. In this work, homology modelling, molecular docking and pharmacophore studies were deployed to assist the rationalization of the structure-activity relationships of known FPR2 agonists. The developed pharmacophore hypothesis was then used in parallel with the homology model for the design of novel ligand structures and in virtual screening. In the first round of optimization compound 8, with a cyclopentane core, was chosen as the most promising agonist (β-arrestin recruitment EC50=20nM and calcium mobilization EC50=740nM). In a human neutrophil static adhesion assay, compound 8 decreased the number of adherent neutrophils in a concentration dependent manner. Further investigation led to the more rigid cycloleucines (compound 22 and 24) with improved ADME profiles and maintaining FPR2 activity. Overall, we identified novel cyclopentane urea FPR2 agonists with promising ADMET profiles and the ability to suppress the inflammatory process by inhibiting the neutrophil adhesion cascade, which indicates their anti-inflammatory and pro-resolving properties.

Diastereomeric Cyclopentane-Based Maltosides (CPMs) as Tools for Membrane Protein Study.

Amphiphilic agents, called detergents, are invaluable tools for studying membrane proteins. However, membrane proteins encapsulated by conventional head-to-tail detergents tend to denature or aggregate, necessitating the development of structurally distinct molecules with improved efficacy. Here, a novel class of diastereomeric detergents with a cyclopentane core unit, designated cyclopentane-based maltosides (CPMs), were prepared and evaluated for their ability to solubilize and stabilize several model membrane proteins. A couple of CPMs displayed enhanced behavior compared with the benchmark conventional detergent, n-dodecyl-β-d-maltoside (DDM), for all the tested membrane proteins including two G-protein-coupled receptors (GPCRs). Furthermore, CPM-C12 was notable for its ability to confer enhanced membrane protein stability compared with the previously developed conformationally rigid NBMs [J. Am. Chem. Soc. 2017, 139, 3072] and LMNG. The effect of the individual CPMs on protein stability varied depending on both the detergent configuration (cis/trans) and alkyl chain length, allowing us draw conclusions on the detergent structure-property-efficacy relationship. Thus, this study not only provides novel detergent tools useful for membrane protein research but also reports on structural features of the detergents critical for detergent efficacy in stabilizing membrane proteins.

Synthesis of the cyclopentane core of pepluanin A

The jatrophane class of natural products exhibit a wide range of biological activities with certain members of this family of complex sesquiterpenes being P-glycoprotein inhibitors. Considerable attention has been paid to the synthesis of biologically active jatrophanes although very few have succumbed to total synthesis. Herein we report a synthesis of the cyclopentane core of pepluanin A, a potent P-glycoprotein inhibitor, that features an iodocarbocyclization and an invertive acetal formation as key steps.

Pactamycin and Its Derivatives: Improved Synthesis Route

Stereoselective construction of the cyclopentane core 21 of pactamycin (1) was achieved from symmetric cyclohexadiene 7. Our synthetic strategy features catalytic Rh‐mediated desymmetric aziridination of the cyclohexadiene derivative, selective ring‐opening reaction at the C2 position of sulfonylaziridine with NaN3, ring‐contraction of cyclohexene 9 by ozonolysis followed by intramolecular aldol reaction via enamine intermediate 11, and construction of the two consecutive tetra‐substituted carbon centers by stereoselective epoxidation of the exo‐methylene moiety of 14c with DMDO, followed by methylation reaction. Introduction of the urea unit on tetra‐substituted carbon of 16 was achieved by amidation and subsequent Hofmann rearrangement.

Total Synthesis of Pactalactam, an Imidazolidinone-Type Pactamycin Analogue.

The first total synthesis of pactalactam was accomplished using substrate-controlled stereoselective aziridination and regioselective aziridine ring-opening to construct three continuous amino groups on an octasubstituted cyclopentane core. The cyclopentane framework was obtained by ring-closing metathesis and aldol coupling using a l-threonine-derived oxazoline compound. Cyclic urea formation, m-acetylphenyl group introduction by Chan-Lam coupling, and primary alcohol-selective acylation yielded the reported pactalactam structure. The presence of pactalactam in the fermentation broth of pactamycin-producing bacteria was also confirmed.

Enantio- and Diastereoselective Synthesis of Latanoprost using an Organocatalyst.

An enantioselective total synthesis of latanoprost was achieved. Its chiral cyclopentane core structure was constructed through an organocatalyst-mediated [3+2]-cycloaddition reaction, and chirality in the ω-side chain was generated by prolinate-anion-mediated α-aminoxylation of an aldehyde. Highly diastereoselective domino acetalization and an oxy-Michael reaction were key steps for the generation of C9 chirality.

Correction to Synthetic Study on Pactamycin: Stereoselective Synthesis of the Cyclopentane Core Framework.

ADVERTISEMENT RETURN TO ISSUEPREVAddition/CorrectionNEXTORIGINAL ARTICLEThis notice is a correctionCorrection to Synthetic Study on Pactamycin: Stereoselective Synthesis of the Cyclopentane Core FrameworkAtsumi Goto, Satoshi Yoshimura, Yuta Nakao, Makoto Inai, Tomohiro Asakawa, Masahiro Egi, Yoshitaka Hamashima, Mitsuru Kondo, and Toshiyuki Kan*Cite this: Org. Lett. 2018, 20, 3, 896Publication Date (Web):January 24, 2018Publication History Received4 January 2018Published online24 January 2018Published inissue 2 February 2018https://doi.org/10.1021/acs.orglett.7b04009Copyright © 2018 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views961Altmetric-Citations-LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (501 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Concise Synthesis of a Cyclopentane Intermediate Possessing All Nitrogen Functionalities for Pactamycin

Pactamycin, a potent antitumor and antimicrobial antibiotic, possesses a densely functionalized cyclopentane core structure. This paper describes the concise synthesis of an advanced intermediate for synthesizing the enantiomer of pactamycin that contains the cyclopentane skeleton bearing all the necessary amino functions with correct stereochemistries.

Synthetic Study on Pactamycin: Stereoselective Synthesis of the Cyclopentane Core Framework.

The cyclopentane core framework 23 of pactamycin (1) was synthesized in 14 steps from symmetric cyclohexadiene 11. Our synthetic strategy features Rh-mediated catalytic desymmetrization of 10 via aziridination and then regioselective ring-opening reaction of sulfonylaziridine 9 with NaN3, ring-contraction of cyclohexene 14 by ozonolysis followed by intramolecular aldol reaction, and stereoselective construction of the sequential tetrasubstituted carbons by dihydroxylation and methylation reaction. Stereospecific incorporation of amine on tetrasubstituted carbon was achieved by Curtius rearrangement and subsequent carbamide formation.

Asymmetric total synthesis of (R)-α-cuparenone, (S)-cuparene and formal synthesis of (R)-β-cuparenone through Meinwald rearrangement and ring closing metathesis (RCM) reaction

Asymmetric synthesis of enantiopure cuparenoid sesquiterpenes (R)-α-cuparenone, (S)-cuparene and a formal synthesis of (R)-β-cuparenone was presented in this article. Meinwald rearrangement of an enantiopure trisubstituted 2,3-epoxy alcohol derivative was the key reaction employed to construct the quaternary streocenter in the target molecules. Ring closing metathesis (RCM) reaction was explored in the final stage of synthesis to access the cyclopentane core of the natural products.

Functionalized cyclopentenes through a tandem NHC-catalyzed dynamic kinetic resolution and ambient temperature decarboxylation: mechanistic insight and synthetic application.

An unusual room temperature β-lactone decarboxylation facilitated a five-step enantioselective formal synthesis of the cyclopentane core of an estrogen receptor β-agonist. A computational study probed the underlying factors facilitating unprecedented, rapid decarboxylation. Aryl substitution promotes faster reaction in the retro-[2+2] as a result of conjugative stabilization with the forming olefin. Additionally, the configuration of the α-ester in these fused β-lactones leads to differential decarboxylation rates.

Highly stereoselective synthesis of cyclopentanes bearing four stereocentres by a rhodium carbene-initiated domino sequence.

Stereoselective synthesis of a cyclopentane nucleus by convergent annulations constitutes a significant challenge for synthetic chemists. Though a number of biologically relevant cyclopentane natural products are known, more often than not, the cyclopentane core is assembled in a stepwise fashion due to lack of efficient annulation strategies. Herein, we report the rhodium-catalyzed reactions of vinyldiazoacetates with (E)-1,3-disubstituted 2-butenols generate cyclopentanes, containing four new stereogenic centers with very high levels of stereoselectivity (99% ee, >97 : 3 dr). The reaction proceeds by a carbene–initiated domino sequence consisting of five distinct steps: rhodium–bound oxonium ylide formation, [2,3]-sigmatropic rearrangement, oxy-Cope rearrangement, enol–keto tautomerization, and finally an intramolecular carbonyl ene reaction. A systematic study is presented detailing how to control chirality transfer in each of the four stereo-defining steps of the cascade, consummating in the development of a highly stereoselective process.

Recent Developments in the Stereocontrolled Synthesis of Highly Substituted Cyclopentane Core Structures: From Drug Discovery Research to Natural Product Synthesis

The cyclopentane carbocyclic ring system, while ubiquitous in nature, is not usually considered a privileged core structure for the development of a drug candidate due, in part, to a perceived synthetic intractability of stereochemically complex target molecules. In this review, we demonstrate that the cyclopentane motif has been utilized as an effective core scaffold for several highly successful medicinal chemistry programs and, thus, has provided an underappreciated yet significant value for biomedical research. Moreover, the modern synthetic methods highlighted in this work offer a wealth of attractive and accessible technologies for the stereocontrolled construction of exceedingly complex cyclopentanoid chemotypes of natural and unnatural origin. We contend that the cyclopentane framework should be regarded as a privileged scaffold for drug discovery research and that expanded screening campaigns of novel cyclopentane- based small molecule libraries for therapeutically relevant biological properties will have a favorable impact on the development of the active pharmaceutical ingredients (APIs) of tomorrow. Keywords: Cyclopentane, carbocycle, drug discovery, medicinal chemistry, stereocontrolled synthesis.

Approach to the functionalized cyclopentane core of marine prostanoids by applying a radical cyclization of β-disubstituted acrylates

A synthetic approach to highly functionalized cyclopentanes that incorporate adjacent secondary and tertiary alcohols is described. These systems, prepared in one step by a ketyl radical cyclization of β-disubstituted acrylates, represent the core of the marine prostanoid family of natural products.