Cyclopentenone Derivatives Research Articles

Rapid access to the core skeleton of the [3 + 2]-type dimeric pyrrole–imidazole alkaloids by triplet ketone-mediated C–H functionalization

The ability of triplet ketones to abstract a hydrogen atom from hydrocarbons is reminiscent of that of the high-spin metal-oxo complexes in C–H oxidation enzymes. In practice, the reactivity of triplet ketones is easier to control and applicable to promoting a wider range of reactions. We demonstrate herein the synthetic utility of triplet ketone-mediated C-addition of methanol to cyclopentenone derivatives with an expedient synthesis of the core skeleton of the [3 + 2]-type dimeric pyrrole–imidazole alkaloids. Remarkably, this photochemical C–H functionalization reaction is highly regioselective and can tolerate a good range of functional groups.

Синтез и оценка антипролиферативной активности арил(гетарил)производных циклопентенона — аналогов комбретастатина A-4

На основе удобного синтетического протокола получен ряд ранее неизвестных ди- и три-арил(гетарил)производных циклопентенона и проведен первичный скрининг на противоопухолевую активность на 4 линиях клеток человека: Т-клеточного лейкоза (Jurkat), карциномы легких (A-549), рака кишечника (HCT-116) и аденокарциномы молочной железы (MCF-7). Найдено, что среди исследованных веществ наибольшей цитотоксичностью обладает 2-(3,4,5-триметоксифенил)-3-(4-метоксифенил)циклопент-2-ен-1-он. Однако, несмотря на его цитотоксическую активность в опытах in vitro, противоопухолевая активность на лимфоцитарный лейкоз Р388 у мышей не выявлена.

Atrichodermones A–C, three new secondary metabolites from the solid culture of an endophytic fungal strain, Trichoderma atroviride

An endophytic fungal strain named Trichoderma atroviride was isolated from the bulb of Lycoris radiata. Following cultivation on rice medium, a novel 3-amino-5-hydroxy-5-vinyl-2-cyclopenten-1-one dimer, atrichodermone A (1), a new cyclopentenone derivative, atrichodermone B (2), and a new sesquiterpene, atrichodermone C (3), together with three known cyclopentenone derivatives (4–6) were isolated. Their structures were elucidated by extensive spectroscopic (UV, IR, ECD, HRESIMS, and NMR) data analyses, and absolute configurations of the new compounds were determined by comparing their experimental ECD spectra with structurally similar compounds and computational analyses of their electronic circular dichroism (ECD) spectra. Compounds 1–3 were evaluated for their cytotoxicity against HL60 and U937 cell lines, as well as anti-inflammatory effect against the production of the pro-inflammatory cytokines TNF-α and IL-1β.

A DFT study on the mechanism of Rh-catalyzed competitive 1,2- versus 1,3-acyloxy migration followed by [5+1] and [4+1] cycloadditions of 1,4-enynes with CO

The mechanisms of the [RhCl(CO)2]2-catalyzed intramolecular cycloadditions of 3-acyloxy-1,4-enynes (ACEs) by CO with concominant acyloxy (OAc) migrations have been extensively investigated using density functional theory (DFT) calculations. All geometries were optimized at the B3LYP/6-31 + G(d) level (LANL2DZ for Rh). The effect of the nature of alkynes, terminal vs internal, has been rationalized by modelling possible intermediates and transition states for competitive 1,2- vs 1,3-migrations of acyloxy group and for further possible transformations with terminal and methyl substituted starting enynes. Experimental and mechanistic studies indicate that the formation reaction of the functionalized cyclopentenones involved a Saucy-Marbet 1,3-OAc migration of ACEs with terminal alkynes and subsequent [4 + 1] cycloaddition with CO, while the reaction for cyclohexadienones proceeded by a [5 + 1] type cycloaddition ACEs of substituted alkynes involving a Rautenstrauch 1,2-OAc migration by carbonylation. The acyloxy migration step is found to be the rate determining step from the DFT study and the predicted regioselectivity is in harmony with the experimental result. The calculations presented herein will contribute to understanding and controlling this effective Rh (I) catalyzed transformation reactions of 1,2 and 1,3-acyloxy migration followed by cycloaddition for further bicyclic cyclohexadienone and cyclopentenone derivatives in obtaining custom made products.

Formation of Bicyclic Cyclopentenone Derivatives by Robinson-Type Annulation of Cyclic β-Oxoesters Containing a 1,4-Diketone Moiety

Robinson-type cyclopentannulations of cyclic β-oxoesters possessing a 1,4-diketone moiety are accomplished under four different Brønsted basic reaction conditions. Using pyrrolidine/acetic acid in DMSO, an oxohexahydrocyclopenta[a]indene (42%) and an N-Boc-protected oxohexahydrocyclopenta[c]pyridine derivative (62%) are obtained with retention of the ester moieties. The latter compound defines an interesting new scaffold for medicinal chemistry with three positions allowing further derivatizations. The use of KOtBu in DMSO or NaH in toluene leads to cyclopentene derivatives with either partial ester saponification and decarboxylation or displacement of the ester moiety within the carbon skeleton. With aqueous KOH, the cyclopentannulations are successful in almost all cases, but with the ester moieties cleaved off. The respective bicyclic and tricyclic products are obtained in good to excellent yields. The 1,4-diketone starting materials are prepared by cerium-catalyzed oxidative coupling of β-oxoesters with isopropenyl acetate. Alternatively, a two-step sequence consisting of α-propargylation followed by palladium-catalyzed alkyne hydration is used.

Synthesis and Pharmacological Evaluation of a Novel Series of Cyclopentenone Derivatives

A novel series of cyclopent-2-enone derivatives have been synthesised by the reaction of 4-hydroxy-3,4-diphenylcyclopent-2-enone, cyclic secondary amines, phosphorus reagents, hexamethylphosphoramide and Lawesson's reagent in boiling toluene/THF. The chemical structures of new compounds were identified by1H NMR,13C NMR,31P NMR and mass spectra. Furthermore, the structure of one of the synthesised compounds has been confirmed using single crystal X-ray diffraction. The pharmacological evaluation results of antilung and anticolon carcinoma cell line properties for the products are discussed.

Water excellent solvent for the synthesis of bifunctionalized cyclopentenones from furfural

The transformation of furfural into functionalized cyclopentenone derivatives is a smart process to advance the sustainable synthesis of important chemicals from biomass.

Facile reductive oxy-Nazarov cyclization of 2-methoxy-2, 4-hexadienoates

Reduction of 2-methoxy-2, 4-hexadienoates with Dibal-H in toluene at −78°C resulted in a facile formation of 5-hydroxyl cyclopentenone derivatives. This novel transformation was proposed as a variant of the oxy-Nazarov cyclization of the corresponding 2-methoxy aldehyde intermediate via the cationic Al-chelate as depicted in Fig. 2a.

ChemInform Abstract: Synthesis of 2‐Cyclopentenone Derivatives via Palladium‐Catalyzed Intramolecular Carbonyl α‐Alkenylation.

2-Cyclopentenone derivatives have been efficiently synthesized from 5-bromo-5-hexen-2-ones via palladium-catalyzed intramolecular carbonyl α-alkenylation followed by double-bond migration under mild reaction conditions.

Synthesis of 2-Cyclopentenone Derivatives via Palladium-Catalyzed Intramolecular Carbonyl α-Alkenylation.

2-Cyclopentenone derivatives have been efficiently synthesized from 5-bromo-5-hexen-2-ones via palladium-catalyzed intramolecular carbonyl α-alkenylation followed by double-bond migration under mild reaction conditions.

Structurally Diverse Metabolites from the Soft Coral Sinularia verruca Collected in the South China Sea.

Nineteen metabolites with diverse structures, including the rare pyrroloindoline alkaloid verrupyrroloindoline (1), the unprecedented highly fused benzosesquiterpenoid verrubenzospirolactone (2), the new asteriscane-type sesquiterpenoid 10-deoxocapillosanane D (3), and the two new cyclopentenone derivatives (4S*,5S*)-4-hydroxy-5-(hydroxymethyl)-2,3-dimethyl-4-pentylcyclopent-2-en-1-one (4) and (S)-4-hydroxy-5-methylene-2,3-dimethyl-4-pentylcyclopent-2-en-1-one (5), were isolated from a South China Sea collection of the soft coral Sinularia verruca. Eleven previously described marine metabolites (7-15, 18, and 19) were also obtained as well as three new EtOH-adduct artifacts (6, 16, and 17). The structures of the new compounds were elucidated by extensive spectroscopic analysis and by comparison with previously reported data. Compounds 4, 5, and 16 showed protection against the cytopathic effects of HIV-1 infection with EC50 values of 5.8-34 μM, and 4, 6, and 16 exhibited inhibition against LPS-induced NO production with IC50 values of 24-28 μM.

A study on the biosynthesis of hygrophorone B12 in the mushroom Hygrophorus abieticola reveals an unexpected labelling pattern in the cyclopentenone moiety

The hitherto unknown natural formation of hygrophorones, antibacterial and antifungal cyclopentenone derivatives from mushrooms, was investigated for hygrophorone B12 in Hygrophorus abieticola Krieglst. ex Gröger & Bresinsky by feeding experiments in the field using 13C labelled samples of d-glucose and sodium acetate. The incorporation of 13C isotopes was extensively studied using 1D and 2D NMR spectroscopy as well as ESI-HRMS analyses. In the experiment with [U-13C6]-glucose, six different 13C2 labelled isotopomers were observed in the 2D INADEQUATE spectrum due to incorporation of [1,2-13C2]-acetyl-CoA. This labelling pattern demonstrated that hygrophorone B12 is derived from a fatty acid-polyketide route instead of a 1,4-α-d-glucan derived anhydrofructose pathway. The experiment with [2-13C]-acetate revealed an unexpected incorporation pattern in the cyclopentenone functionality of hygrophorone B12. Four single-labelled isotopomers, in particular [1-13C]-, [2-13C]-, [3-13C]-, and [4-13C]-hygrophorone B12, were detected that showed only half enrichment in comparison to the respective labelled alkyl side chain carbons. This labelling pattern indicates the formation of a symmetrical intermediate during hygrophorone B12 biosynthesis. Based on these observations, a biogenetic route via a 4-oxo fatty acid and a chrysotrione B homologue is discussed.

ChemInform Abstract: Synthesis of New Photochromic Diarylethenes of Cyclopentenone Series by Nazarov Reaction.

AbstractThe Nazarov reaction of divinylketones of type (I) affording cyclopentenone derivatives of type (II) is the key step in the synthesis of new photochromic diarylethenes.

New Furan and Cyclopentenone Derivatives from the Sponge-Associated Fungus Hypocrea Koningii PF04.

Two new furan derivatives, hypofurans A and B (1 and 2), and three new cyclopentenone derivatives, hypocrenones A–C (3–5), along with seven known compounds (6–12), were isolated from a marine fungus Hypocrea koningii PF04 associated with the sponge Phakellia fusca. Among them, compounds 10 and 11 were obtained for the first time as natural products. The planar structures of compounds 1–5 were elucidated by analysis of their spectroscopic data. Meanwhile, the absolute configuration of 1 was determined as 2R,3R by the comparison of the experimental and calculated electronic circular dichroism (ECD) spectra. All the isolates were evaluated for their antibacterial and antioxidant activity. Compounds 1, 10, and 12 all showed modest antibacterial activity against Staphylococcus aureus ATCC25923 (MIC, 32 μg/mL). In addition, compounds 1, 10 and 11 exhibited moderate DPPH radical scavenging capacity with IC50 values of 27.4, 16.8, and 61.7 µg/mL, respectively.

A Novel C21 Cyclopentenone Derivative from Cipadessa Cinerascens

A new C21 cyclopentenone derivative, Cipacyclonone (1), was isolated from the leaves of Cipadessa cinerascens. Its structure was elucidated on the basis of spectroscopic analysis, including extensive 1D- and 2D-NMR techniques. Compound 1 showed strong cytotoxicity activity against HL-60 and A-549 cell lines, with IC50 values of 1.2 and 3.0 microM, respectively.

Identification and Bioactivity of Compounds from the Mangrove Endophytic Fungus Alternaria sp.

Racemic new cyclohexenone and cyclopentenone derivatives, (±)-(4R*,5S*,6S*)-3-amino-4,5,6-trihydroxy-2-methoxy-5-methyl-2-cyclohexen-1-one (1) and (±)-(4S*,5S*)-2,4,5-trihydroxy-3-methoxy-4-methoxycarbonyl-5-methyl-2-cyclopenten-1-one (2), and two new xanthone derivatives 4-chloro-1,5-dihydroxy-3-hydroxymethyl-6-methoxycarbonyl-xanthen-9-one (3) and 2,8-dimethoxy-1,6-dimethoxycarbonyl-xanthen-9-one (4), along with one known compound, fischexanthone (5), were isolated from the culture of the mangrove endophytic fungus Alternaria sp. R6. The structures of these compounds were elucidated by analysis of their MS (Mass), one and two dimensional NMR (nuclear magnetic resonance) spectroscopic data. Compounds 1 and 2 exhibited potent ABTS [2,2′-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid)] scavenging activities with EC50 values of 8.19 ± 0.15 and 16.09 ± 0.01 μM, respectively. In comparison to Triadimefon, compounds 2 and 3 exhibited inhibitory activities against Fusarium graminearum with minimal inhibitory concentration (MIC) values of 215.52 and 107.14 μM, respectively, and compound 3 exhibited antifungal activity against Calletotrichum musae with MIC value of 214.29 μM.

ChemInform Abstract: Cyclopentenone Derivatives and Polyhydroxylated Steroids from the Soft Coral Sinularia acuta.

AbstractFour new polyhydroxylated steroids and the racemic form of cyclopentanone, sinularone J (IV), are isolated along with four known steroids, one known cyclopentanone derivative, and one known butenolide derivative from the soft coral Sinularia acuta.

ChemInform Abstract: Catalytic Enantioselective Quick Route to Aldol‐Tethered 1,6‐ and 1,7‐Enynes from ω‐Unsaturated Aldehydes.

AbstractDirect cross‐aldol reaction between ω‐unsaturated aldehydes and propargylic aldehydes is developed to yield functionalized 1,6‐ and 1,7‐enynes and the conversion of these products to bicyclic cyclopentenone derivatives by Pauson—Khand reaction is demonstrated.

Organic breakdown products resulting from hydrothermal carbonization of brewer’s spent grain

Hydrothermal carbonization of brewer’s spent grain resulted in a solid hydrochar and an aqueous phase rich in macromolecular dissolved organic matter. Both phases were analyzed with regard to low molecular weight organic compounds (MW<500Da) in lyophilized form by exhaustive solvent extraction followed by pre-chromatographic derivatization and GC/MS-analysis. Low molecular weight acids, O-functionalized phenols, cyclopentenone derivatives, and benzenediols accounted for the majority of organic analytes in both hydrothermal carbonization product streams while being absent in solvent extracts of the pristine biomass. The pattern of short chain functionalized acids in the pristine biomass and in the hydrothermally produced matrices turned out very different. Acylglycerines as the most abundant lipids in pristine brewer’s spent grain were quantitatively hydrolyzed under hydrothermal conditions. The recovery of total fatty acids present in the pristine biomass amounted to 19%. The major fraction of hydrophobic breakdown products including fatty acids, fatty alcohols, and sterols was sorbed onto the hydrochar.

Cyclopentenone derivatives and polyhydroxylated steroids from the soft coral Sinularia acuta.

Four new polyhydroxylated steroids, 1-4, and the racemic form of cyclopentenone 9, together with four known steroids, 5-8, one known cyclopentenone derivative, 10, and one known butenolide derivative, 11, were isolated from the soft coral Sinularia acuta collected from Weizhou Island of Guangxi Province, P. R. China. Their structures were elucidated on the basis of spectroscopic analyses and by comparison of the corresponding data with those previously reported. The cytotoxicities of the isolates 1-11 in vitro against the selected tumor cell lines HL-60, HeLa, and K562 were evaluated. Compounds 2 and 5 showed potent cytotoxicities against HL-60 cell lines with IC50 values of 7.3 and 9.9 μM, respectively. Compounds 5 and 6 showed moderate activities against K562 cell lines with IC50 values of 10.9 and 11.7 μM, respectively, while compounds 1, 2, and 6 showed weak activities against HeLa cell lines with respective IC50 values of 44.8, 27.1, and 18.2 μM. This is the first report on chemical and bioactivity research of S. acuta.