Electrochemical oximation of alcohols was realized with KNO(3) as the nitrogen source mediated by tin microspheres.

To inform hypotheses regarding the relative importance of chemolithotrophic metabolisms in geothermal environments, we calculated free energy yields of 26 chemical reactions potentially supporting chemolithotrophy in two US Great Basin hot springs, taking into account the effects of changing reactant and product activities on the Gibbs free energy as each ...

The synthesis of β-Gal-(1→3)-α-GalNAc-(1→3)-β-GalNAc allyl trisaccharide as the outer core fragment of Burkholderia cepacia pv. vietnamiensis lipooligosaccharide was accomplished through a concise, optimized, multi-step synthesis, having as key steps three glycosylations, that were in-depth studied performing them under several conditions. The target trisaccharide was designed with an allyl aglycone in ...

Isodon species have been much studied for their biologically active ingredients, and Sun and co-workers report the isolation, characterization, and biological activities of twenty three compounds, including three new ones. The new compounds from Isodon coetsa are neolignan, triterpenoid, and diterpenoid types, showing that Isodon species have diverse types of ...

Two birds one stone: A new atom-economical one-pot approach to enantioselective chiral drug synthesis, involving in situ multistep organocatalyst formation and the application of the reaction for multistep sequential synthesis of β-adrenergic blockers is disclosed.

Air pollution by nitrogen oxides represents a serious environmental problem in urban areas where numerous sources of these pollutants are concentrated. One approach to reduce the concentration of these air pollutants is the light-induced oxidation in the presence of molecular oxygen and a photocatalytically active building material, e.g., paints, roof ...

A highly diastereo- and enantioselective organocatalytic protocol for the synthesis of biologically important spirocyclopentaneoxindoles containing the oxime functional group from easily accessible 3-allyl-substituted oxindoles and nitroolefins has been developed by a one-pot Michael addition/ISOC/fragmentation sequence.

The C21-C34 fragment of the potent FKBP12-binding macrolide antascomicin B was prepared using Ireland-Claisen and allylic diazene rearrangements to establish the C26/C27 and the C23 stereocenters, respectively. Directed hydrogenation installed the C29 β-configuration. The fragment possesses 7 of the 11 fixed stereocenters contained in the natural product.

The thiazole-thiazoline fragment of the marine natural product largazole, a potent histone deacetylase 1 inhibitor, has been synthesized in 5 steps. The methodology provides rapid access to thiazole-4-carbonitrile, thiazole-4-carbimidate, thiazole-oxazoline and other thiazole-thiazoline derivatives which are important intermediates in the total synthesis of many natural products.

A concise synthesis of cytimidine was developed utilizing tandem Cu-mediated N-aryl amidations followed by global deprotection. This sequence exploits a regioselective coupling of an iodobenzamide with a halopyrimidine that allows the union of three fragments in a single synthetic manipulation and will permit the efficient and rapid diversification of the ...

A formal total synthesis of palmerolide A has been accomplished by assembling three fragments by means of successive Julia-Kocienski olefination, Yamaguchi esterification, and ring-closing metathesis (RCM). Our initial efforts to combine the first two fragments through a Julia-Kocienski reaction between a secondary sulfone and a ketone were not successful; nevertheless, it ...

Interest in the synthesis of the C(23)-C(40) fragment 2 of tetrafibricin prompted us to develop a new method for the synthesis of 1,5-syn-(E)-diols. Toward this end, the kinetically controlled hydroboration of allenes 6, 33, ent-39, 42 and 45 with the Soderquist borane 25R were studied. Tetrabutylammonium allenyltrifluoroborate 45 gave superior ...

The formal synthesis of (+)-sorangicin A was completed by two independent routes. Both approaches feature a cross metathesis reaction to form the C29-C30 bond to arrive at the bicyclic ether/tetrahydropyran fragment. Formation of the C15-C16 olefin to unite the dihydropyran fragment with the rest of the molecule was achieved by ...

Synthesis of a C1-C27 intermediate in the synthesis of Apoptolidin D is reported. The synthesis involves a combination of Heck coupling and Horner-Wadsworth-Emmons reaction for the C1-C7 trienoate portion and an efficient Suzuki cross coupling protocol for C10-C13 diene portion.

Reinvestigation of the Lewis acid catalyzed rearrangement of some open-chain permethyloligosilanes with the Al(Fe)Cl(3) catalyst system exhibited several cases of additional reactivity: namely, a fragmentation/cyclization reaction. Introduction of (trimethylsilyl)methyl substituents into the oligosilane substrates strongly facilitated this reaction, yielding cyclic or bicyclic carbacyclosilanes. Investigations concerning the composition of the catalyst ...

The Mukaiyama cross aldol reaction of α-fluoro-, α-chloro-, and α-bromoacetaldehyde-derived (Z)-tris(trimethylsilyl)-silyl enol ethers furnishing anti-β-siloxy-α-haloaldehydes is described. A highly diastereoselective, one-pot, sequential double aldol process, affording novel β,δ-bissiloxy-α,γ-bishaloaldehydes is developed. Reactions are catalyzed by C6F5CHTf2 and C6F5CTf2AlMe2 (0.5-1.5 mol%) and provide access to halogenated polyketide fragments.

Cheminformatics protocols have been developed and assessed that identify a small set of fragments which can represent the compounds in a chemical library for use in fragment-based ligand discovery. Six different methods have been implemented and tested on Input Libraries of compounds from three suppliers. The resulting Fragment Sets have ...

A synthesis of the fully protected C-ring fragment of the tricyclic diterpene fusicoccin A is reported. The desired cyclopentenyl halides 5a and 5b are obtained in a total of 9 steps. Key transformations of the synthesis sequence are a non-conventional Cr-catalyzed allylic oxidation of a protected intermediate cylcopentenone, a diastereoselective ...

A new approach to the synthesis of the C7-26 fragment of amphidinolides G and H was developed. In the sequence, the C7-18 portion of this fragment was synthesized using an acetylide coupling protocol, while an Evans alkylation and Sharpless asymmetric dihydroxylation were employed as key steps in construction of the ...

A topological defect is identified in a Cu2O surface oxide grown on Cu(111). Using scanning tunneling microscopy (STM), we observed the formation of pentagonal and heptagonal rings within the Cu2O surface oxide. These structures break the symmetry of the hexagonal oxide surface and are a consequence of the presence of ...

A synthetic route to the carboline disaccharide domain (2) of shishijimicin A (1) has been developed. The convergent synthesis relies on a novel application of the Reetz-Müller-Starke reaction to form the central, sulfur-bearing quaternary carbon center and addition of the carboline structural motif as a dianion to a disaccharide aldehyde ...

An efficient synthetic methodology for 3-hydroxy-2,2-dimethyloctynoic acid (DHOYA) and several variants, which are increasingly common fragments encountered in bioactive marine cyanobacterial metabolites, was developed. These fragments were obtained in three steps via a tertiary aldol reaction utilizing an Evans' chiral auxiliary to afford the desired stereochemistry at the β-hydroxy carbon. ...

The kibdelones are hexacyclic tetrahydroxanthones and potent anticancer agents isolated from an Australian microbe. Herein, we describe the synthesis of a chiral, non-racemic iodocyclohexene carboxylate EF ring fragment of the kibdelones employing an intramolecular iodo halo-Michael aldol reaction and its merger with an ABCD ring fragment to afford the congener ...

A novel and robust synthesis of the fragment, 2-amino-5-tert-butylpyridine, has been described, which has been shown to have improved physicochemical properties over 4-tert-butylaniline, when considering drug-like properties. The synthesis also yields fragments containing more highly oxidised precursors to the tert-butyl group as intermediates. These fragments can be incorporated into final ...

The synthesis of all key fragments of the marine macrolide leiodelide A is described. The polyoxygenated northern subunit is derived from d-xylose, while the southern subunit is rapidly assembled via an aldol reaction and Horner-Wadsworth-Emmons olefination. This highly convergent approach will allow for rapid modification and assembly of several isomers ...

Hybrids of vinblastine and phomopsin, designed by a molecular modelling study, were elaborated in order to target tubulin. The key step of the synthesis (fragmentation and insertion of vindoline) was mediated by an internal N-carboxyanhydride (or O-acylcarbamate). This reaction was diastereospecific and addition of silver salts could reverse the diastereoselectivity. ...

A Brønsted acid-catalyzed Prins-type cyclization sequence to construct spirooxindole pyrans in high yields and excellent diastereoselectivity has been developed. The combination of a β-hydroxy dioxinone fragment and isatin dimethyl acetal generate oxa-spirooxindoles efficiently. These compounds are diversifiable scaffolds that tap into the rich chemistry of dioxinones.

Efficient syntheses of suitably functionalized top and bottom fragments of tetrafibricin are described. The bottom fragment is prepared by two consecutive Kocienski-Julia couplings, while the top fragment synthesis features a dithiane alkylation and a Horner-Wadsworth-Emmons reaction.

The asymmetric synthesis of key fragments of the phytotoxic toxins botcinolide/botcinin is reported. The synthesis of 1 and 1a are based on a convergent route via esterification and alkene metathesis of fragments A, B or C, B, which were obtained by Evans aldol condensation and stereoselective crotylation, respectively.

The linker-equipped disaccharide, 8-amino-3,6-dioxaoctyl 2,6-dideoxy-2-acetamido-3-O-β-d-galactopyranosyluronate-β-d-glucopyranoside (10), was synthesized in eight steps from acetobromogalactose and ethyl 4,6-O-benzylidene-2-deoxy-2-trichloroacetamido-1-thio-β-d-glucopyranoside. The hydroxyl group present at C-4(II) in the last intermediate, 8-azido-3,6-dioxaoctyl 4-O-benzyl-6-bromo-2,6-dideoxy-2-trichloroacetamido-3-O-(benzyl 2,3-di-O-benzyl-β-d-galactopyranosyluronate)-β-d-glucopyranoside (9), is positioned to allow further build-up of the molecule and, eventually, construction of the complete hexasaccharide. Global deprotection (9→10) was ...

Phytochemical investigation of Annona squamosa twigs, resulted in isolation and identification of twelve known (1-12) compounds among them one 1-(4-β-D-glucopyranosyloxyphenyl)-2-(β-D-glucopyranosyloxy)-ethane (11) is synthetically known but first time isolated from natural sources. Their structures were elucidated using 1D and 2D NMR spectroscopic analysis. The isolated compounds (2-8, 11) were evaluated for ...

Development of ulcerative colitis was accompanied by the activation of iNOS/COX-2/5-LOX and increased contents of nitric oxide (NO), prostaglandin E(2) (PGE(2)), and leukotriene B(4) (LTB(4)). The following information was assessed: morphological changes, activity of nitric oxide-synthase, content of nitric oxide, and indexes of lipoperoxidation processes in the mucous membrane of ...

Two new flavonol glycosides were isolated from the 1-butanol (1-BuOH)-soluble fraction of a methanol (MeOH) extract of the leaves of Indigofera zollingeriana, along with four flavonol glycosides and three known megastigmane glucosides. The structures of the new compounds were elucidated by spectroscopic analyses as kaempferol 3-O-β-D: -(2″-O-β-D: -apiofuranosyl)glucopyranoside 7-O-α-L: -rhamnopyranoside ...

Phytochemical investigation of the methanolic extract from the aerial parts of Agrimonia pilosa led to the isolation of three compounds, (-)-aromadendrin 3-O-β-D-glucopyranoside, desmethylagrimonolide 6-O-β-D-glucopyranoside, and 5,7-dihydroxy-2-propylchromone 7-O-β-D-glucopyranoside, together with nine known compounds, agrimonolide 6-O-glucoside, takanechromone C, astragalin, afzelin, tiliroside, luteolin, quercetin, isoquercetrin, and quercitrin. Their structures were determined by various ...

In order to study the human intestinal transit of flavan-3-ol C-glycosides, several C-glycosyl derivatives were prepared by non-enzymatic reaction of (+)-catechin with α-D-glucose, α-D-galactose and α-D-rhamnose, respectively. In contrast to literature data, we propose that the reaction mechanism proceeds in analogy to the rearrangement of flavan-3-ols during epimerization under alkaline ...

The occurrence of the two new cis-fused A/B rings furostanol saponins (25S)-26-O-β-d-glucopyranosyl-5β-furostan-1β,3β,22α,26-tetraol-1-O-β-d-glucopyranoside and (25S)-26-O-β-d-glucopyranosyl-5β-furostan-1β,2β,3β,5β,22α,26-hexaol and the known compounds (25S)-26-O-β-d-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-α-l-rhamnopyranosyl-(1→2)-O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranoside and (25S)-26-O-β-d-glucopyranosyl-5β-furostan-3β,22α,26-triol-3-O-β-d-glucopyranosyl-(1→2)-O-β-d-glucopyranoside, trans-resveratrol, (+) catechin and (-) epicatechin in the rhizomes of Smilax aspera is reported. All saponins have been isolated as their 22-OMe derivatives, which were further subjected to extensive ...

A variety of substituted pentadiynols, -diynals, and -diynones have been prepared en route to precursors to dialkynyl carbenes (R(1)-C≡C-C-C≡C-R(2)). In light of the marginal stability associated with these simple systems, several strategies were required to assemble the carbon backbones. The requisite five-carbon skeletons were prepared using 4 + 1, 3 ...

A new flavanone glycoside, naringenin-7-O-β-D-glucuronopyranoside, and a new flavonol glycoside, 6-hydroxykaempferol-7-O-β-D-glucuronopyranoside were isolated together with 12 known compounds, 5 flavone glycoside; hispidulin-7-O-β-D-glucuronopyranoside, apigenin-7-O-β-D-methylglucuronopyranoside, hispidulin-7-O-β-D-methylglucuronopyranoside, hispidulin-7-O-β-D-glucopyranoside, apigenin-7-O-β-D-glucopyranoside, a flavonol; kaempferol, two flavone; apigenin, and luteolin, a flavanone glycoside; eriodictyol-7-O-β-D-glucuronopyranoside, and three phenol glycoside; arbutin, salidroside, and 3,5-dihydroxyphenethyl alcohol-3-O-β-D-glucopyranoside from Centaurea urvillei ...

A new prenylated flavonoid (1) and two new aliphatic glycosides (2, 3) have been isolated from leaves of Euodia meliaefolia (Hance) Benth., together with three known compounds, (2R,3R)-5,7,4'-trihydroxy-8-(3-methylbut-2-enyl)dihydroflavonol 7-O-β-D: -glucopyranoside (phellamurin) (4), (2R,3R)-dihydroquercetin 3'-O-β-D: -glucopyranoside (5), and (7R,8S)-dihydrodiconiferyl alcohol 4-O-β-D: -glucopyranoside (6). Their structures were determined on the basis of ...

Two new glycosides, 1,6-di-O-syringoyl-β-D-glucopyranose (1) and quercetin 3-O-[(3-O-syringoyl-α-L-rhamnopyranosyl)-(1→6)-β-D-glucopyranoside] (2), along with seven known compounds were isolated from the MeOH extract of Leonurus japonicus. The structures of these compounds were elucidated by spectral analysis.

A new abietane diterpene, glypensin A (1) and four known compounds, 12-acetoxy-ent-labda-8(17), 13E-dien-15-oic acid (2), quercetin 3-O-α-L-arabinofuranoside (3), quercetin 3-O-β-D-galactopyranoside (4), β-sitosterol (5) were isolated from the branches and leaves of Glyptostrobus pensilis (Staut.) Koch. Their structures were determined by MS, 1D- and 2D-NMR means. Compound 1 showed cytotoxicity on ...

The synthesis of methyl α-l-rhamnopyranosyl-(1→2)-β-d-galactopyranoside and methyl α-l-rhamnopyranosyl-(1→2)-3-(glycer-2-yl-phosphate)-β-d-galactopyranoside disaccharides from the Streptococcuspneumoniae type 23F capsular polysaccharide is reported. A simple protecting group strategy was followed using commercially available monosaccharides and phosphorylating reagents. H-Phosphonate and phosphoramidite coupling chemistries were explored for introducing the phosphodiester. Hydrazine hydrate was found to be a ...

Three new olean-12-ene derivatives (1-3), together with known urs-12-ene-3beta, 28-diol (4) were isolated from the stem root of Cylicodiscus gabunensis. The structures of the new compounds were established by chemical and spectroscopic means as beta-amyrin-n-nonyl ether (1), 22alpha-hydroxyolean-12-en-3beta-yl-beta-D-galactopyranoside (2), and 24-hydroxyolean-12-en-3beta-yl-beta-D-glucopyranoside (3).

Two novel flavonoids, kaempferol 3- O- α-L-rhamnopyranosyl (1-3) (2,4-di- O-acetyl-α-L-rhamnopyranosyl) (1-6) β-D-galactopyranoside (1) and kaempferol 3- O-α-L-rhamnopyranosyl (1-3) (4-O-acetyl-α-L-rhamnopyranosyl) (1-6) β-D-galactopyranoside (2), along with three known ones, kaempferol-3- O-β-D-galactopyranoside (3), kaempferol (4), and 7-hydroxychromone (5), have been isolated from the leaves of Actinidia valvata Dunn, and their structures were elucidated ...

As part of our chemical studies on the medical plants in Uzbekistan aimed at searching for new drug leads, we have examined the aerial parts of Mediasia macrophylla. This has resulted in the isolation of four new glucosides, together with 30 known compounds. The structures of new compounds were elucidated ...

4'-O-[beta-D-Apiosyl(1-->2)]-beta-D-glucosyl]-5-hydroxyl-7-O-sinapylflavanone (1), 3-(4-acetoxy-3,5-dimethoxy)-phenyl-2E-propenyl-beta-D-glucopyranoside (2), 3-(4-hydroxy-3,5-dimethoxy)-phenyl-2E-propenyl-beta-D-glucopyranoside (3), 5,7-dimethoxy-4'-O-beta-D-glucopyranoside flavanone (4), 4',5-dimethoxy-7-hydroxy flavanone (5), and 5,7-dimethoxy-4'-hydroxy flavanone (6), were isolated from the organic extracts of Viscum album L. (European Mistletoe). These compounds were studied for their anti-glycation and antioxidant properties. The structures of new compounds 1 and 2 were deduced on the ...

Studies on Conyza bonariensis (L.) Cronq. led to the isolation of two new glycosides trivially named as erigeside E and F (1-2), along with two new source compounds; benzyl-beta-D-glucopyranoside (3) and 2-phenylethyl-beta-D-glucopyranoside (4). Compounds 1, 3, and 4 are aromatic glycosides, while compound 2 is an alkyl glycoside. Their structures ...

Two new lupane type saponins, along with one known saponin were isolated from leaves of Oplopanax horridus (Devil's Club). The structures of the two new compounds were elucidated as 3alpha-hydroxy-lup-20(29)-ene-23, 28-dioic acid-3-O-beta-D-glucopyranoside (2) and 24-nor-3-oxo-lup-20(29)-en-28-oic acid-28-O-alpha-L-rhamnopyranosyl(1''' --> 4")-beta-D-glucopyranosyl(1" --> 6')-beta-D-glucopyranoside (3) on the basis of spectroscopic analysis and chemical evidence. ...

To study the chemical constituents of Saxifraga stolonifera (L.) Meeb., chromatographic techniques were applied to separate and purify the compounds, and their structures were confirmed on the basis of physicochemical properties and spectral data. Ten compounds were isolated and identified as 5-O-methylnorbergenin (1), 3, 4-dihydroxyallylbenzene-4-O-beta-D-glucopyranoside (2), (7R, 8S)-4, 9, 9'-trihydroxyl-3-methoxyl-7, ...

The synthesis of (2R,S)-1-(6-methoxy-4-(methoxymethyl)-1H-indol-5-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol and (2R,S)-1-(4-methoxy-6-(methoxymethyl)-1H-indol-5-yloxy)-3-(2-(2-methoxyphenoxy)ethylamino)propan-2-ol is described. The compounds were tested for electrographic, antiarrhythmic, hypotensive, and spasmolytic activity, as well as for alpha(1)-, alpha(2)- and beta(1)-adrenoceptor binding affinity.