<i>cis</i>‐<i>trans</i>‐and Intramolecular enol‐enolic equilibrium of β‐ketoaldehydes

Noy, R. S.; Gindin, V. A.; Ershov, B. A.; Kol'tsov, A. I.; Зубков, В. И.

doi:10.1002/mrc.1270070302

Cited by 18 publications

(6 citation statements)

References 8 publications

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“…Presumably, 11 first results in the generation of 13 , which is in equilibrium with its aldehyde tautomer 14 (see eq ). We prepared and isolated, by a reported method, an equilibrium mixture of 13 and 14 , and subjected the mixture to the conditions in Table . However, we did not observe the formation of 12 , suggesting that the latter is formed from the reaction of 13 or 14 with 12 under the influence of the cobalt catalyst 1b .…”

Section: Resultsmentioning

confidence: 99%

Radical Isomerization and Cycloisomerization Initiated by H• Transfer

et al. 2016

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Under H2 pressure, Co(II)(dmgBF2)2L2 (L = H2O, THF) generates a low concentration of an H• donor. Transfer of the H• onto an olefin gives a radical that can either (1) transfer an H• back to the metal, generating an isomerized olefin, or (2) add intramolecularly to a double bond, generating a cyclized radical. Transfer of an H• back to the metal from the cyclized radical results in a cycloisomerization. Both outcomes are favored by the low concentration of the cobalt H• donor, whereas hydrogenation and cyclohydrogenation are more likely with other catalysts (when the concentration of the H• donor is high).

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Section: Resultsmentioning

confidence: 99%

Radical Isomerization and Cycloisomerization Initiated by H• Transfer

et al. 2016

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“…The predominant structures with respect to the enol, enolate, and cis - and trans -forms of aroylacetaldehydes are discussed by means of their NMR spectra in various solvents. Most of them are in equilibirium with the enthalpy difference of less than a few kJ/mol and rapidly interconverting . According to the Curtin–Hammett principle, the most populating species does not necessarily lead to the main product.…”

Section: Resultsmentioning

confidence: 99%

Mechanistic and Exploratory Investigations into the Synthesis of 1,3,5-Triaroylbenzenes from 1-Aryl-2-propyn-1-ones and 1,3,5-Triacetylbenzene from 4-Methoxy-3-buten-2-one by Cyclotrimerization in Hot Water in the Absence of Added Acid or Base

et al. 2012

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Neat 1-phenyl- and 1-(p-tolyl)-2-propyn-1-ones (1 and 1', respectively) were heated in water without any additive at 150 °C for 2 h to give 1,3,5-tribenzoyl- and 1,3,5-tri-(p-toluoyl)benzenes (2 and 2', respectively) in 74 and 52% yields, respectively. The crossed reactions of 1 with the enolate of p-toluoylacetaldehyde (3') and 1' with the enolate of benzoylacetaldehyde (3) were carried out to give unsymmetrically substituted 1-toluoyl-3,5-dibenzoylbenzene (Ph2Tol) and 1,3-ditoluoyl-5-benzoylbenzene (PhTol2), respectively, corroborating the previously proposed reaction mechanism in which 3 and 3' that are formed by rate-determining nucleophilic attack of HO(-) on 1 and 1' or its conjugate acids formed by subsequent protonation would serve as a common intermediate for the formation of 2, 2' and the acetophenone derivatives as byproducts. When 4-methoxy-3-buten-2-one (4) was heated in hot pure water without any additive at 150 °C for 30 min, 1,3,5-triacetylbenzene (5) was obtained in an isolated yield of 77% just by removing water by filtering the crystalline product from the cooled reaction mixture. The reaction did not take place in the absence of water. Slow decompositions of 5 in water set in at the temperature of 300 °C for 30 min.

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“…One of these phytotoxins, stemphyloxin I, was characterized as an enolic ,B-ketoaldehyde compound. A series of ,8-ketoaldehydes synthesized by Noy et al (5) and their NMR spectra were investigated. It was found that the enolization occurs exclusively at the formyl group and that the preferred confirmation depends on the polarity of the solvent.…”

Section: Discussionmentioning

confidence: 99%

A Novel Enolic β-Ketoaldehyde Phytotoxin Produced by Stemphylium botryosum f. sp. lycopersici

Barash¹,

Pupkin²,

Netzer³

et al. 1982

Plant Physiol.

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A new phytotoxin, stemphyloxin I, C21H3205, was isolated from cultures of the pathogenic fungus Stemphylium botryoswn f. sp. lycopersici. The toxin is a tricyclic compound possessing a most unusual /8-ketoaldehyde group. Injection of stemphyloxin I into a tomato leaflet caused unlimited necrotic spots and a loss of turgor, which at higher toxin concentration wilted the whole compound leaf. (8,9). Typical symptoms consist of light to dark brown or grayish spots 1 to 10 mm in diameter. A rapid wilting of the foliage often takes place in advanced stages of disease development (9). S. botryosum isolates of different host specificity can also infect alfalfa (2) or lettuce (6). Differential effect of phytotoxic compounds produced by this pathogen on susceptible and resistant alfalfa clones (3) or lettuce cultivars (1) has been reported. The former and latter observations as well as the nature of the disease syndrome on tomato plants suggest that toxic metabolites excreted by S. botryosum f. sp. lycopersici may be involved in pathogenesis.In a preliminary study we have found that culture filtrates of S. botryosum f. sp. lycopersici contain several phytotoxic compounds which are capable of producing symptoms normally associated with the disease. The present work describes the isolation, chemical characterization, and biological activity of one of these phytotoxins. Tomato plants were grown in the greenhouse at 23 + 2°C. The plants were inoculated at the age of 6 to 8 weeks by spraying the leaves with a conidial suspension of about 6 x 104 conidia/ml. Sucrose (1%) was added to the conidial suspension. The inoculated plants were kept for 48 h in a moist chamber at 23 ± 2°C in the dark. They were then transferred back to the greenhouse. The first visible symptoms appeared as irregular spots 3 to 4 days after inoculation.Green and white cell cultures of L. esculentum Mill. cv. San Marzano were obtained from Dr. J. Gressel, The Weizmann Institute of Science (13). The cells were grown in 100 ml fresh B-5 liquid medium (4) containing 0.1 ml/l kinetin and 0.5 mg/l naphthalene acetic acid sodium salt (13) Incorporation of radioactive amino acids into macromolecules of tomato cell cultures was carried out according to a modified procedure of Zilkah and Gressel (14). Exponentially growing cells were fitered through Nybolt um, GG47) under aseptic conditions and diluted with fresh medium to give a final pack volume of 10%1o. For each treatment, five 0.5-ml aliquots 23 www.plantphysiol.org on May 11, 2018 -Published by Downloaded from

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cis‐trans‐and Intramolecular enol‐enolic equilibrium of β‐ketoaldehydes

Cited by 18 publications

References 8 publications

Radical Isomerization and Cycloisomerization Initiated by H• Transfer

Radical Isomerization and Cycloisomerization Initiated by H• Transfer

Mechanistic and Exploratory Investigations into the Synthesis of 1,3,5-Triaroylbenzenes from 1-Aryl-2-propyn-1-ones and 1,3,5-Triacetylbenzene from 4-Methoxy-3-buten-2-one by Cyclotrimerization in Hot Water in the Absence of Added Acid or Base

A Novel Enolic β-Ketoaldehyde Phytotoxin Produced by Stemphylium botryosum f. sp. lycopersici

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