Showing papers by "Jon Clardy published in 1990"
395 citations
TL;DR: A convergent asymmetric synthesis of the antinoeplastic macrolide antibiotic cytovaricin has been achieved through the synthesis and coupling of the illustrated spiroketal and polyol glycoside subunits.
Abstract: A convergent asymmetric synthesis of the antinoeplastic macrolide antibiotic cytovaricin has been achieved through the synthesis and coupling of the illustrated spiroketal and polyol glycoside subunits. All absolute steroechemical relationships within the target structure were ultimately controlled by the use of asymmetric aldol, alkylation, or epoxidation methodology. Union of the two subnits was accomplished by Julia-Lythgoe trans olefination, providing direct access to a suitable macrolactonization substrate
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TL;DR: The fermentation, isolation and structure determination of naphterpin are reported, which succeeded in isolating a new antioxidative agent, named naph terpin, from Ishigaki Island, Okinawa Prefecture, Japan.
Abstract: Active oxygen species cause a variety of diseases such as inflammation, autoimmune disease, diabetes, rheumatism, cardiovascular diseases and cancer-initiation1>2). Thus, it could be expected that antioxidative agents may prevent these diseases. We have screened antioxidants of microbial origin by employing the Yagi method after minor modification using rat liver microsome free from vitamin E3). As a result, we succeeded in isolating a new antioxidative agent, named naphterpin. In this paper, we report the fermentation, isolation and structure determination of naphterpin. The producing microorganism Streptomyces sp. CL190 was isolated from Ishigaki Island, Okinawa Prefecture, Japan. It was inoculated into test tubes containing 12ml of the seed medium consisting of glucose 2.5%, soybean meal 1.5%, dry yeast 0.2% and CaCO3 0.4% (pH 6.2, before sterilization). After incubation at 27°Cfor 2 days on a reciprocal shaker, an aliquot of the broth (2ml) was transferred into 500-ml Erlenmeyer flasks each containing 100 ml of the samemediumas the seed culture and incubated at 27°C for 2 days on a rotary shaker. The
74 citations
TL;DR: Two new imidazole alkaloids were isolated from a Micronesian sponge, Leucetta sp.
Abstract: Two new imidazole alkaloids were isolated from a Micronesian sponge, Leucetta sp. Kealiiquinone (2) is a naphtoquinone which appears to be biogenetically derived from 1, which is a dibenzyl-substituted imidazole. Pyronaamidine (1) is cytotoxic against KB cells, MIC=5 μg/mL
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TL;DR: Kalihinene and isokalihinol B, cytotoxic diterpene isonitriles have been isolated from the marine sponge Acanthella klethra as discussed by the authors.
TL;DR: In this paper, the scope of the mercuric chloride induced cyclization reaction was further delineated and an efficient enantioselective synthetic route to didemnenones A and B was developed.
Abstract: An efficient, flexible enantioselective synthetic route to didemnenones A and B was developed, which allowed assignment of the absolute configurations to didemnenones A-D. In the course of these studies, the scope of the mercuric chloride induced cyclization reaction 6 was further delineated. It was found that, in forming a cis-6-oxabicyclo [3.3.0] oct-3-en-2-one system, cyclopentadienyl silyl enol ethers bearing ∈-alkynes in the form of terminally unsubsituted propargylic ethers or acetals would undergo the reaction with apparently exclusive anti selectivity
TL;DR: In this article, four new oxindole alkaloids, 20-hydroxydihydrorankinidine, N -desmethoxyhumantenine, 15-hydroxyhumantene and gelsemoxonine have been isolated from Gelsemium elegans, and their structures assigned by spectral and X-ray crystallographic analyses.
TL;DR: Fijiensin, a novel phytotoxic metabolite, was isolated from a culture of the fungus Mycosphaerella fijiensis, the causal agent of Black Sigatoka disease of banana, by X-ray analysis.
Abstract: Fijiensin, a novel phytotoxic metabolite, was isolated from a culture of the fungusMycosphaerella fijiensis, the causal agent of Black Sigatoka disease of banana. Fijiensin is phytotoxic on various banana cultivars, but not toward non-host plants. The structure of fijiensin was determined by X-ray analysis.
TL;DR: Trikentramine, an unusual pyrrole, has been isolated from the Senegalese sponge Trikentrion and characterized by spectroscopic and X-ray diffraction techniques.
TL;DR: In this paper, a koumine-related alkaloid extract of the whole plant of Gelsemium elegans has been obtained, whose structure and stereochemistry were deduced by spectral methods and confirmed by X-ray diffraction analysis.
TL;DR: In this paper, two isoquinoline fungal derivatives, pyrenoline-A and -B, were isolated from the culture fluid of Pyrenophora teres, a pathogen of barley, and characterized by spectroscopic and X-ray diffraction techniques.
TL;DR: Palmosalide C (3) belongs to the rare bakkane class of sesquiterpenoids, but it is epimeric to the known terrestrial bakkenolides at the C-7 spiro center.
TL;DR: A triterpenoid cleocarpone has been isolated from the whole plant of Cleome brachycarpa and its structure was elucidated through chemical and spectral studies and confirmed by X-ray crystallography as discussed by the authors.
TL;DR: In this article, a tactic which has provided satisfactory diastereomeric resolution in such a case is described, and the configuration of the resulting isomers is established crystallographically.
Abstract: This paper describes a tactic which has provided satisfactory diastereomeric resolution in such a case. Configuration of the resulting isomers is established crystallographically
TL;DR: A single crystal x-ray diffraction study revealed a β-D configuration for the 2,4,6-trideoxy -4 - thiomethyl - ribo hexopyranose fragment of esperamicin A1 as mentioned in this paper.
TL;DR: An extract of the whole plant of Ruellia brittoniana has afforded the new glycoside 2-O-alpha-D-galactopyranosyl glycerol hexaacetate, which was deduced by spectroscopic methods and X-ray crystallographic analysis.
Abstract: An extract of the whole plant of Ruellia brittoniana has afforded the new glycoside 2-O-alpha-D-galactopyranosyl glycerol hexaacetate [1]. Its structure and absolute configuration were deduced by spectroscopic methods and X-ray crystallographic analysis.
TL;DR: In this paper, the synthese enantiospecifique de l'aminoacide du titre a ete effectuee via la reaction of l'hydrazine avec le dimethoxy-2',2' ethyl-3 oxirannecarboxylate-2 de methyle.
Abstract: La synthese enantiospecifique de l'aminoacide du titre a ete effectuee via la reaction de l'hydrazine avec le dimethoxy-2',2' ethyl-3 oxirannecarboxylate-2 de methyle (A); la synthese de l'hydroxy-3 proline est effectuee via la reaction de (A) avec l'ammoniac
Patent•
03 Apr 1990TL;DR: Members of a novel class of organic nitriles related to an indole alkaloid of Dithyrea wislizenii (Cruciferae) have been discovered to be patent feeding inhibitors of the fall armyworm and European corn borer as mentioned in this paper.
Abstract: Members of a novel class of organic nitriles related to an indole alkaloid of Dithyrea wislizenii (Cruciferae) have been discovered to be patent feeding inhibitors of the fall armyworm and European corn borer.