First total syntheses and configurational assignments of cytotoxic trichodenones A–C

Total syntheses of cytotoxic trichodenones A–C, produced by a strain of Trichoderma harzianum from the sponge Halichondria okadai, have been achieved, and the natural trichodenones B and C have been established to have (4R,1′R)- and (1′R)-configurations, respectively. From this synthesis and chiral HPLC analysis, it was deduced that the major molecule with R-configuration coexists with its enantiomer in natural trichodenone A.     

A New Sesquiterpene from Michelia yunnanensis

MicheliayunnanensisFr.exFin.etGagnisaChinesetraditionalmedicinefortreatmentofinflammation.Weobtainedanewsesquiterpene1,throughinvestigationoftheplant,togetherwithtwoknowncompoundsPhydroxyarbusculinAZIandparthenolide32.Compound1,needlecrystal,mp146"C,[a];z-2.56(c0.391,CHC13),displayedstrongabsorptionsforhydroxylandestergroups(3339cm-',3298cm',1750..-i,1742cm')inIR.HRFAB MSmlz:389.2168[(M l) ,Cafe.forC19H33OS:389.21751agreedwithmolecularformulaC19H32O8.Fourunsaturations,twoofwhichwer…     

First mechanosynthesis of piperlotines A,C, and derivatives through solvent-free Horner–Wadsworth–Emmons reaction

Piperlotines are natural products characterized by an α,β-unsaturated amide moiety. These compounds found wide applications in Medicinal Chemistry like antibacterials, cytotoxic agents, anticoagulants, among others. To date, diverse methods of synthesis have been reported for piperlotines, but involving the use of catalysts, hazard reagents, anhydrous media or coupling reagents. Thus, in this work, we developed a greener method of synthesis of piperlotines A, C, and derivatives, through mechanochemical activation under solvent-free conditions. The reaction of a β-amidophosphonate, K₂CO₃, and an aromatic aldehyde afforded target compounds in moderate to good yields (46–77%), in an open atmosphere by grinding. It is worth to mention that this mechanochemical process was under thermodynamic control because just E isomer was isolated for every reaction. Moreover, synthesized piperlotines have been predicted by means of chemoinformatic analysis as potential therapeutic agents for the treatment of arthritis or cancer.     

Alkaloids from stems of Ervatamia yunnanensis

Six indole alkaloids were isolated from the stems of Ervatamia yunnanensis. Among them, yunnanensine (I) is new. The other five are known alkaloids, namely: 19,20-E-vallesamine (II), 19s-heyneanine (HI), ibogaine (IV), ibogamine (V), coronaridine (VI). The structural elucidation of the alkaloids was based on spectral means.     

A New Iridoid Glucoside from Lagotis yunnanensis

Phytochemical investigation of Lagotis yunnanensis led to the isolation andidentification of a new iridoid glucoside 1, named as 10-O-(3, 4-dimethoxy-(E)-cinnamoyl)aucubin.Its structure was elucidated by spectroscopic methods.     

A New Triterpene from the Orchid Pholidota yunnanensis

A new triterpene, 25-methylenecyclopholidonyl p-hydroxy-trans-cinnamate, was isolated from a orchid Pholidota yunnanensis. The structure elucidation and ^1H, ^13C-NMR assignments were achieved by spectral and chemical method.     

Leucomidines A–C,novel alkaloids from Leuconotis griffithii

Two novel indole alkaloids and new quinazoline alkaloids, namely leucomidines A–C (1–3), were isolated from the barks of Leuconotis griffithii. The structures including the absolute configuration were elucidated on the basis of spectroscopic data, chemical means, and CD calculations. The quinazoline alkaloid, 3, is proposed to be derived from the same biogenetic precursor as the indole alkaloids 1 and 2.     

Lycocasuarines A–C,Lycopodium alkaloids from Lycopodiastrum casuarinoides

Three lycodine-type Lycopodium alkaloids (1–3) were isolated from Lycopodiastrum casuarinoides. Their structures were elucidated by spectroscopic analysis, single-crystal X-ray crystallography, and computational methods. Compound 1 possesses a rearranged five-membered ring D resulting from C-8/C-15 cleavage and a new C-7/C-15 linkage. Compound 2 is the first Lycopodium alkaloid found to bear an additional carbon (C-17) directly bonded to C-8, which is particularly unusual from a biogenetic point of view. Compounds 1–3 were evaluated for acetylcholinesterase inhibitory activities.     

Donellanic acids A–C: new cyclopropanic oleanane derivatives from Donella ubanguiensis (Sapotaceae)

Three new cyclopropanic oleanane triterpenoids and ten known compounds were obtained from Donella ubanguiensis using chromatographic methods. The structures were established on the basis of mass spectrometric and NMR data and by comparison with values reported in the literature. The structures of the new compounds were confirmed by X-ray crystallography. A part of the isolated compounds was evaluated for cytotoxic and antimicrobial activities.     

Alkaloids from Stems of Ervatamia yunnanensis (II)

The non-alkaloid chemical constituents, which were isolated from the stems of Ervatamia yunnanensis Tsiang (Apocynaceae), have been reported in previous paper 1. As a part of our continuing research on the isolation of active compounds for anti-addictive …     

Alkaloids from Stems of Ervatamia yunnanensis （Ⅱ）

Six indole alkaloids were isolated from the stems of Ervatamia yunnanensis. Among them, 10-hydroxy-19, 20-dihydroisositsirikine （I） is new. The other five are known alkaloids, namely： matrine （Ⅱ）, 19, 20-dihydroisositsirikine （Ⅲ）, 19-s-voacangarine （Ⅳ）, 1 l＇-methoxyl-19s- heyneanine （Ⅴ）, conodurine （Ⅵ）. The structural elucidation of the alkaloids was based on spectral means.     

Pimprinols A–C,from the terrestrial actinomycete,Streptomyces sp.

A Streptomyces sp. Lv3-13, isolated from the rhizosphere soil of the plant Mespilus germanica, has yielded three new pimprinine derivatives, named pimprinols A–C (1–3) and the unknown (2-aminophenyl)(2-ethyloxazol-5-yl) methanone (4) along with the known compounds 2-ethyl oxazole pimprinine and 2-propyl oxazole pimprinine. The structures of the compounds were elucidated based on spectroscopic methods including UV, HR-ESIMS and 1D, 2D NMR data. Compounds 1–4 were screened for antimicrobial and cytotoxic activities.     

(±)-Rubioncolin D,a pair of enantiomeric naphthohydroquinone dimers from Rubia oncotricha

A pair of novel enantiomeric naphthohydroquinone dimers with an unprecedented spiro[4.5] carbon core, (±)-rubioncolin D (1), were isolated from Rubia oncotricha. The racemic mixture of 1 was separated by chiral column chromatography. Their structures and stereochemistry were elucidated by extensive spectroscopic analysis and electronic circular dichroism calculation. Both compounds (+)-1 and (?)-1 exhibit weak cytotoxicities against A549, SGC-7901 or HeLa cancer cell lines.     

Aphamines A–C,dimeric acyclic diterpene enantiomers from Aphanamixis polystachya

Aphamines A–C (1–3), three pairs of acyclic diterpene dimer enantiomers with an unprecedent ploymerization pattern, were discovered from Aphanamixis polystachya by NMR-guided isolation and chiral resolution. The elucidation of their novel carbon skeletons was achieved based on spectroscopic analysis, exciton chirality, and calculated electronic circular dichroism (ECD). Plausible Claisen rearrangement, 5-exo-trig cyclization, and reduction reactions may play important roles in the polymeric biosynthesis pathway. Compounds 1 and 3 showed inhibitory effects on nitric oxide (NO) production (IC₅₀: 6.71–15.36 μmol/L) and reduced the expression of iNOS in LPS-induced RAW 264.7 macrophages.     

Pseudoferic acids A–C,three novel triterpenoids from the root bark of Pseudolarix kaempferi

Three novel triterpenoids, pseudoferic acids A and B (1 and 2) possessed a unique 16,24-cyclo-26-norlanostane skeleton, and pseudoferic acid C (3) featured a cis-fused D/E-ring system, were isolated from the root bark of Pseudolarix kaempferi. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 2 and 3 exhibited weak inhibitory activities against 11β-HSD1 (11β-hydroxysteroid dehydrogenase 1) with IC₅₀ values of 0.44 (mouse 11β-HSD1) and 0.75 μM (human 11β-HSD1), respectively.     

Siladenoserinols M–P,sulfonated serinol derivatives from a tunicate

Four new sulfonated serinol derivatives, siladenoserinols M–P (1–4), were isolated from a tunicate of the family Didemnidae collected in Indonesia. Their chemical structures were elucidated by the interpretation of NMR and mass spectroscopic data. Two of them (2 and 4) were revealed to be disulfonate serinol derivatives, and the others were monosulfonates. Siladenoserinols A (5) and B (6), which we previously isolated from the same tunicate, inhibited the p53–Hdm2 interaction with an IC₅₀ value of 2.0?μM. However, 1–4 did not inhibit the activity. The result suggested that the acetyl group in the bicyclic ketal unit and/or the glycerophospholipid moiety in 5 and 6 were responsible for the inhibition of the p53–Hdm2 interaction.     

Synthesis of mono-and diphosphorus-substituted proline derivatives containing P–C–N fragments

Russian Chemical Bulletin - Convenient methods for the synthesis of new types of mono-and diphosphorus-substituted proline derivatives containing P–C–N fragments were developed based on...     

Diels–Alder reactions of directly C3-dieneylated chlorophyll derivatives

The [4π?+?2π] cycloaddition of methyl 3-(1,3-butadien-1/2-yl)pyropheophorbides-a with tetracyanoethylene, dimethyl acetylenedicarboxylate, and naphthoquinone gave the corresponding Diels–Alder reaction adducts. The trans-1-substituted 1,3-butadiene was more reactive than its regioisomeric 2-substituent. The oxidation of some cycloadducts gave C3-arylated chlorophyll derivatives, whose ortho-substitution blue-shifted the corresponding Qy absorption maxima in dichloromethane because of the steric repulsion between the aryl and chlorin π-planes.     

A one-pot, four-component synthesis of α-carboline derivatives

A one-pot method for the efficient and simple synthesis of novel 1H-indolo[2,3-b]pyrazolo[4,3-e]pyridines via a four-component condensation reaction of indolin-2-one, 3-oxo-3-phenylpropanenitrile, and various hydrazines and aldehydes in the ionic liquid 1-butyl-3-methylimidazolium bromide ([bmim]Br) is reported.     

Synthesis of PhTAD-substituted dihydropyrrole derivatives via stereospecific C–H amination

Research on Chemical Intermediates - Stereospecific α-amination has been accomplished via addition of N-phenyltriazolinedione (PhTAD) to the allylic position of dihydropyrroles. The aim of...