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Photoinduced and ground state conversions in a cyclic β-thioxoketone. RSC Adv 2021; 12:681-689. [PMID: 35425142 PMCID: PMC8697321 DOI: 10.1039/d1ra09020h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 12/16/2021] [Indexed: 12/30/2022] Open
Abstract
The photochemistry of a cyclic β-thioxoketone (2-methyl-1-(2-thioxycyclohexyl)propan-1-one (MTPO)) is investigated by NMR, UV, and IR experiments supported by DFT calculations. MTPO exists as a tautomeric mixture of an enol and a thiol form. Irradiation at low temperature led to a cis–trans isomerization of the thiol form resulting in a rather unusual enethiol (3). This is followed by a transfer of the isopropyl methine proton onto the carbonyl carbon resulting in yet another enethiol isomer (4). The photoconversion mechanisms without water present are discussed. Photochemical experiments at ambient temperature showed involvement of water in the excited state and resulted in another keto-form (5). The same species was also obtained when the products of the low temperature experiments were kept in the dark at ambient temperature. The photochemistry of a cyclic β-thioxoketone (2-methyl-1-(2-thioxycyclohexyl)propan-1-one (MTPO)) is investigated by NMR, UV, and IR experiments supported by DFT calculations.![]()
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2
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Direct synthesis of sulfinic esters via ultrasound accelerated tandem reaction of thiols and alcohols with N-bromosuccinimide. J Sulphur Chem 2021. [DOI: 10.1080/17415993.2021.1928669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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3
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Strong intramolecular hydrogen bonds and steric effects involving C═S groups: An NMR and computational study. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:154-162. [PMID: 31705583 DOI: 10.1002/mrc.4959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Revised: 10/17/2019] [Accepted: 10/17/2019] [Indexed: 06/10/2023]
Abstract
A number of 5-acyl rhodanines and thiorhodanines with bulky acyl groups (pivaloyl and adamantoyl), not previously available, have been synthesized. The compounds are shown to exist in the enol form. Structures have been calculated using both the MP2 approach and the B3LYP-GD3BJ functional and the 6-311++G(d,p) basis set. Hydrogen bond energies are estimated by subtracting energies of a structure with the OH group turned 180° from those of the intramolecularly hydrogen-bonded one. Properties such as OH chemical shifts, two-bond isotope effects on 13 C chemical shifts, electron densities at the bond critical point from atoms in molecules analysis, and the hydrogen bond energies show that the sterically hindered compounds have stronger hydrogen bonds than methyl or isopropyl derivatives. The combination of oxygen and sulfur derivatives enables a detailed analysis of hydrogen bond energies.
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Ultrasound accelerated sulfonylation of amines by p-acetamidobenzenesulfonyl chloride using Mg–Al hydrotalcite as an efficient green base catalyst. J Sulphur Chem 2016. [DOI: 10.1080/17415993.2016.1193180] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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5
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Benign and efficient preparation of thioethers by solvent-free S-alkylation of thiols with alkyl halides catalyzed by potassium fluoride on alumina. J Sulphur Chem 2016. [DOI: 10.1080/17415993.2016.1150483] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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6
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Ultrasound-Accelerated Synthesis of Asymmetrical Thiosulfonate S-Esters by Base-Promoted Reaction of Sulfonyl Chlorides with Thiols. PHOSPHORUS SULFUR 2015. [DOI: 10.1080/10426507.2015.1034313] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Investigation of peel and leaf essential oils ofCitrus clementinaHort. ex Tan. growing in the south of Vietnam. JOURNAL OF ESSENTIAL OIL RESEARCH 2015. [DOI: 10.1080/10412905.2015.1083491] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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8
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Fast and efficient green synthesis of thiosulfonate S-esters by microwave-supported permanganate oxidation of symmetrical disulfides. J Sulphur Chem 2015. [DOI: 10.1080/17415993.2015.1025404] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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9
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Biological test against breast adenocarcinoma cells (MCF-7) of acylated products of 3-methyl-4 thiorhodanine. ACTA ACUST UNITED AC 2015. [DOI: 10.32508/stdj.v18i1.1035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Rhodanine and its derivatives are not only valued for their interesting chemical properties but also present a wide range of bioactivities and their chemical and pharmacological applications have been investigated. From 3-methyl-4-thiorhodanine we synthesized S-acylated and C-acylated products using (some) carboxylic acid chlorides and the obtained products were studied the anti-proliferative activity by a SRB (sulforhodamine B) assay against a human breast cancer cell line. The results showed that C-acylated products are better inhibitors than S-acylated products.
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Upward Trend in Catalytic Efficiency of Rare-Earth Triflate Catalysts in Friedel-Crafts Aromatic Sulfonylation Reactions. ASIAN J ORG CHEM 2014. [DOI: 10.1002/ajoc.201402067] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Oliveridepsidones A-D, antioxidant depsidones from Garcinia oliveri. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2012; 50:242-245. [PMID: 22407733 DOI: 10.1002/mrc.2862] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 11/01/2011] [Indexed: 05/31/2023]
Abstract
Four new prenylated depsidones, oliveridepsidones A-D, were isolated from the bark of Garcinia oliveri collected in Vietnam. Their structures were elucidated using mainly NMR techniques ((1)H and (13)C NMR, HMQC, HMBC and NOE experiments).
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Abstract
A new geranylated coumarin, (E)-4-(1-hydroxypropyl)-5,7-dihydroxy-6-(3,7-dimethyl-2,6-octadienyl)-8-(3-methyl-1-oxobutyl)coumarin (named surangin D), was isolated from the bark of Mammea siamensis collected in Vietnam, along with four known coumarins, surangins B and C, and theraphins B and C, and seven xanthones, 1,7-dihydroxyxanthone, 7-hydroxy-1-methoxyxanthone, 1,7-dimethoxyxanthone, 1,7-dimethoxy-6-hydroxyxanthone, 1,6,7-trihydroxyxanthone, 1,3,7-trihydroxyxanthone, and 1,7-dihydroxy-3-methoxyxanthone. Their structures were determined by spectroscopic methods (mainly 1D- and 2D-NMR) and preparation of methylated derivatives. The four coumarins, surangins C and D and theraphins B and C, were tested for inhibition of cell proliferation in DLD-1 (colon cancer), MCF-7 (breast adenocarcinoma), HeLa (human cervical cancer) and NCI-H460 (human lung cancer) cell lines using the sulforhodamine B (SRB) assay. In all four cell lines, theraphin C showed the strongest activity (IC₅₀ in the range of 1.6-5.7 µM). Testing the anti-proliferative effect of the methylated derivatives showed reduced cellular effects of all derivatives, indicating that the number and position of free hydroxyl groups were very important for the anti-proliferative effect.
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Friedolanostane, friedocycloartane and benzophenone constituents of the bark and leaves of Garcinia benthami. PHYTOCHEMISTRY 2011; 72:290-295. [PMID: 21168174 DOI: 10.1016/j.phytochem.2010.11.016] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 08/06/2010] [Accepted: 11/15/2010] [Indexed: 05/30/2023]
Abstract
Friedolanostanes, (22Z,24E)-3β-acetoxy-9α-hydroxy-17,14-friedolanosta-14,22,24-trien-26-oic acid, (22Z,24E)-3β,9α-dihydroxy-17,14-friedolanosta-14,22,24-trien-26-oic acid, (22Z,24E)-9α-hydroxy-3-oxo-17,14-friedolanosta-14,22,24-trien-26-oic acid, a friedocycloartane, (22Z,24E)-3α-hydroxy-17,13-friedocycloarta-12,22,24-trien-26-oic acid, and a benzophenone, benthaphenone, together with known compounds (22Z,24E)-3α,9α-dihydroxy-17,13-friedolanosta-12,22,24-trien-26-oic acid, methyl (24E)-3α,23-dihydroxy-17,14-friedolanosta-8,14,24-trien-26-oate, glutinol, lupeol, and stigmasterol, were isolated from leaves and bark of Garcinia benthami. Their structures were elucidated using spectroscopic techniques, mainly 1-D and 2-D NMR spectroscopy, and chemical correlations.
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Effect of 4-methoxyindole-3-carbinol on the proliferation of colon cancer cells in vitro, when treated alone or in combination with indole-3-carbinol. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:8453-8459. [PMID: 20593832 DOI: 10.1021/jf101806t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Consumption of cruciferous vegetables and cancer prevention seem to be positively associated. We present an easy two-step synthesis for 4-methoxyindole-3-carbinol (4MeOI3C), the expected breakdown product of 4-methoxyglucobrassicin during ingestion. 4MeOI3C inhibited the proliferation of human colon cancer cells DLD-1 and HCT 116 with IC(50) values of 116 microM and 96 microM, respectively, after 48 h in vitro, and is therefore a more potent inhibitor than indole-3-carbinol (I3C). 4MeOI3C and I3C combined in different molar ratios inhibited proliferation in a nearly additive to slightly synergistic manner. Proliferation was inhibited by 100 microM 4MeOI3C after 48 h without affecting cell cycle phase distribution, indicating an overall-slowdown effect on the cell cycle. However, 200 microM 4MeOI3C caused a very high level of cell death and an accumulation of living cells in the G(0)/G(1) phase, indicating a concentration-dependent mode of action. We conclude that 4MeOI3C might play a role in the cancer preventive effect of cruciferous vegetables.
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Cytotoxic geranylated xanthones and O-alkylated derivatives of alpha-mangostin. Chem Pharm Bull (Tokyo) 2009; 57:830-4. [PMID: 19652408 DOI: 10.1248/cpb.57.830] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two new geranylated xanthones, 6-O-methylcowanin (4) and oliverixanthone (5), along with five known compounds, cowanin, rubraxanthone, cowaxanthone, cowanol, and beta-mangostin, have been isolated from the bark of Garcinia oliveri. For comparison of their biological activities, one mono- and seven di-O-alkylated alpha-mangostin derivatives were synthesized from alpha-mangostin. The structures of all compounds were assigned by spectroscopic methods (1D and 2D NMR and MS). Cytotoxicity of selected xanthones against MCF-7 and DLD-1 cell lines was examined. Evaluation of the structure-activity relationship showed that alpha-mangostin had the strongest activity, and all the O-alkylated alpha-mangostin derivatives showed reduced activity compared to the naturally occurring alpha-mangostin.
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Fast and green microwave-assisted conversion of essential oil allylbenzenes into the corresponding aldehydes via alkene isomerization and subsequent potassium permanganate promoted oxidative alkene group cleavage. Molecules 2009; 14:3411-24. [PMID: 19783934 PMCID: PMC6255098 DOI: 10.3390/molecules14093411] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2009] [Revised: 09/02/2009] [Accepted: 09/02/2009] [Indexed: 11/16/2022] Open
Abstract
Essential oil allylbenzenes from have been converted quickly and efficiently into the corresponding benzaldehydes in good yields by a two-step "green" reaction pathway based on a solventless alkene group isomerization by KF/Al(2)O(3) to form the corresponding 1-arylpropene and a subsequent solventless oxidation of the latter to the corresponding benzaldehyde by KMnO(4)/CuSO(4).5H(2)O. The assistance by microwave irradiation results in very short reaction times (<15 minutes). The green conversion of eugenol (4-allyl-2-methoxyphenol) into vanillin (4-hydroxy-3-methoxybenzaldehyde) has been carried out in a similar way, requiring however two additional microwave-assisted synthetic steps for acetylation of the hydroxy group prior to the oxidation reaction, and for the final deacetylation of vanillin acetate (4-acetoxy-3-methoxybenzaldehyde) by KF/Al(2)O(3) under solvent-free conditions, respectively.
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Microwave- and Ultrasound-Accelerated Green Oxidation of Alcohols by Potassium Permanganate absorbed on Copper(II) Sulfate Pentahydrate. SYNTHETIC COMMUN 2008. [DOI: 10.1080/00397910801997819] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Ultrasound assisted synthesis of 5,9-dimethylpentadecane and 5,9-dimethylhexadecane--the sex pheromones of Leucoptera coffeella. Molecules 2007; 12:2080-8. [PMID: 17960107 DOI: 10.3390/12082080] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 08/23/2007] [Accepted: 08/23/2007] [Indexed: 11/16/2022] Open
Abstract
Racemic 5,9-dimethylpentadecane and 5,9-dimethylhexadecane, the major and minor constituents, respectively, of the sex pheromone of Leucoptera coffeella, have been synthesized from citronellol in 56-58% overall yield through six steps. Ultrasound irradiation efficiently supported tosylation of alcohols (two steps) as well as the subsequent cross coupling reactions with the pertinent Grignard reagents (also two steps).
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Intramolecular hydrogen bonding of novel o-hydroxythioacetophenones and related compounds evaluated by deuterium isotope effects on 13C chemical shifts. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2007; 45:245-52. [PMID: 17290362 DOI: 10.1002/mrc.1957] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A new class of compounds, the 2-hydroxythioacetophenones, and related compounds have recently been synthesized. The hydrogen-bond system has been characterized by NMR chemical shifts and deuterium isotope effects on these as well as by DFT calculations. Use of solid-state (13)C NMR has enabled measurements of the intrinsic deuterium isotope effects of the most abundant tautomer of beta-thioxoketones. The compounds show very interesting long-range deuterium isotope effects on the thiocarbonyl carbon. The intramolecular hydrogen bonds of o-hydroxythioacetophenones are found to be slightly stronger than those of the corresponding acetophenones. The reactivity and stability of the compounds can be related to hydrogen bonding and to the presence of electron donating substituents.
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Improved synthesis methods of standards used for quantitative determination of total isothiocyanates from broccoli in human urine. J Chromatogr B Analyt Technol Biomed Life Sci 2007; 852:229-34. [PMID: 17307405 DOI: 10.1016/j.jchromb.2007.01.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2006] [Revised: 12/28/2006] [Accepted: 01/14/2007] [Indexed: 11/20/2022]
Abstract
A well-known method for quantification of isothiocyanates (ITCs) and their metabolites is the condensation reaction with 1,2-benzenedithiole to produce 1,3-benzodithiole-2-thione, which can be quantified by high-performance liquid chromatography. Standards of an ITC metabolite and 1,3-benzodithiole-2-thione are required for this assay but are not commercially available. In the present study, we report on an improved synthesis of the ITC metabolite N-acetyl-S-(N-4-methylsulfinylbutylthiocarbamoyl)-L-cysteine and 1,3-benzodithiole-2-thione. The standards were used to quantify the urinary excretion of ITCs from 10 healthy subjects who consumed 350 g broccoli. The excretion was investigated throughout 48 h showing a cumulative urinary ITC excretion of 49.1+/-25.2% of the dose.
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Characterization of the N-methoxyindole-3-carbinol (NI3C)--induced cell cycle arrest in human colon cancer cell lines. Toxicol Sci 2004; 83:126-35. [PMID: 15483186 DOI: 10.1093/toxsci/kfi008] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Recent results have shown that indole-3-carbinol (I3C) inhibits the cellular growth of human cancer cell lines. In some cruciferous vegetables, another indole, N-methoxyindole-3-carbinol (NI3C), is found beside I3C. Knowledge about the biological effects of NI3C is limited. The aim of the present study was to show the effect of NI3C on cell growth of two human colon cancer cell lines, DLD-1 and HCT-116. For the first time it is shown that NI3C inhibits cellular growth of DLD-1 and HCT-116 and that NI3C is a more potent inhibitor of cell proliferation than I3C. In addition to the inhibition of cellular proliferation, NI3C caused an accumulation of HCT-116 cells in the G2/M phase, in contrast to I3C, which led to an accumulation of the colon cells in G0/G1 phase. Furthermore, NI3C delays the G1-S phase transition of synchronized HCT-116 cells. The indole-mediated cell-cycle arrest may be related to the increased levels of the CDK-inhibitors p21 and p27 (only induced by NI3C). Only an initial increase of cdc2 protein was observed, whereas prolonged treatment with NI3C or I3C downregulates the mRNA and proteins of cyclin-dependent kinases and cyclins. These results indicate that both NI3C and I3C inhibit the proliferation of human colon cells but via different mechanisms.
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Abstract
Thioacetylacetone and its variously deuterated isotopomers have been investigated using electronic and vibrational spectroscopy combined with quantum chemical calculations. Thioacetylacetone is known for its photochromic properties, but the structures of the initial and final forms have been the subject of a long debate. Analysis of the IR spectra recorded in low-temperature argon and xenon matrices, room-temperature solutions, and in the gas phase has allowed us to establish the nature of the photochromic species and of its precursor. Similar to the case of another beta-thioxoketone, monothiodibenzoylmethane, the photo-product has been assigned to the nonchelated SH exo-rotamer of the (Z)-enethiol tautomeric form, whereas the dominant ground-state species corresponds to the chelated (Z)-enol tautomeric form. Detailed vibrational assignments have been proposed for both forms based on quantum chemical calculations and polarization experiments. In the case of the chelated (Z)-enol species prevailing in the ground state, a second-order perturbative anharmonic analysis at the B3LYP/cc-pVTZ level indicated strong anharmonic effects associated with the intramolecular hydrogen bond, leading to a shift of more than 600 cm-1 of the wavenumber of the OH-stretching vibration. A small fraction of the SH endo-rotameric chelated (Z)-enethiol form was also detected under unperturbed conditions. The (Z)-enethiol form can be converted into the (Z)-enol form by irradiation at 290 nm.
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Synthesis of ß-Thioxoketones: byt-Butyllithium-Promoted Claisen Condensation Reaction of Ketones with Thionoesters. SYNTHESIS-STUTTGART 2002. [DOI: 10.1055/s-1985-31304] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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27
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The electronic structure of .beta.-thioxoketones. A photoelectron spectroscopic study of the enol-enethiol tautomerism of thioacetylacetone and related compounds. J Am Chem Soc 2002. [DOI: 10.1021/ja00396a008] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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beta.-Thioxo ketones. 8. X-ray photoelectron-spectroscopic study of the enol-enethiol tautomerism of thioacetylacetone and related .beta.-thioxo ketones. J Am Chem Soc 2002. [DOI: 10.1021/ja00386a014] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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beta.-Thioxo ketones. Part 12. The enol-enethiol tautomerism of simple nonaromatic .beta.-thioxo ketones. An approach to quantitative description based upon proton NMR and UV spectral parameters and the adaptation of these into a simplified model of the tautomeric equilibrium. J Am Chem Soc 2002. [DOI: 10.1021/ja00264a012] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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beta.-Thioxo ketones. 2. Preparation and structure of some five- and six-membered 2-acylcycloalkanethiones and 2-thioacylcycloalkanones. J Org Chem 2002. [DOI: 10.1021/jo00439a004] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Variable temperature 1H and 13C NMR spectroscopic investigation of the enol–enethiol tautomerism of β-thioxoketones. Isotope effects due to deuteron chelation. J Mol Struct 2000. [DOI: 10.1016/s0022-2860(00)00458-0] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Intramolecular hydrogen bonding of the enol forms of β-ketoamides and β-ketothioamides. Deuterium isotope effects on 13C chemical shifts. J Mol Struct 1996. [DOI: 10.1016/0022-2860(95)09147-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Structural Dynamics of 4-Hydroxy-6-Mercaptothiopyran-2-Thiones. PHOSPHORUS SULFUR 1993. [DOI: 10.1080/10426509308038147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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SOLVENT AND SUBSTITUENT INFLUENCE ON THE CHELATE PROTON NMR CHEMICAL SHIFT OF AROMATIC β-THIOXOKETONES. PHOSPHORUS SULFUR 1991. [DOI: 10.1080/10426509108045719] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Long-range deuterium isotope effects in tautomeric ?-thioxoketones. A1H and13C NMR study. J PHYS ORG CHEM 1991. [DOI: 10.1002/poc.610040405] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Determination of tautomeric phenotypes of β-thioxo esters and characterization of the tautomeric enethiolic constituents by means of13C NMR spectroscopy. ACTA ACUST UNITED AC 1984. [DOI: 10.1002/mrc.1270220105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Thioglycollates and β-thiopropionates
with SH and/or CO2H groups yield pronounced (M-H)- ions in their
negative ion spectra, not molecular negative ions as we previously reported.
Compounds containing R1-S-CH2- functionality (R1
= alkyl or aryl) undergo α cleavage to S to yield R1S- and
-S-CH2-ions. Hydrogen rearrangements are rare but thioglycollates R1SCH2CO2H
characteristically eliminate R1SH to yield CH2CO2-.
Fragment negative ions generally do not contain enough excess energy to allow
decomposition, so we have studied their collision induced dissociations. Simple
cleavage reactions are usual: for example BuSCH2CO2-
decomposes to yield both BuS- and BuSCH2-.
Group migration to sulfur is also observed; for example, ions -SCH2CO2R2
(R2 = alkyl or aryl) eliminate carbon dioxide to produce R2SCH2-
as the major product.
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β-Thioxoketones. Part 9. A dynamic1H nuclear magnetic resonance spectroscopic study of thioacetylacetone and related β-thioxoketones. Direct observation of the enol and enethiol tautomeric constituents and their interconversion. ACTA ACUST UNITED AC 1983. [DOI: 10.1039/p29830001321] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Definitive evidence for the existence of the hydrogen-bonding enol form of non-aromatic β-thioxoketones. X-Ray crystal structure of 1-(1-methylcyclopropyl)-3-thioxobutan-1-one. ACTA ACUST UNITED AC 1983. [DOI: 10.1039/c39830000496] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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A study of the tautomerism of 2- and 4-ethoxycarbonylthiolan-3-ones implicating stereochemical effects of ring-substitution. Tetrahedron 1981. [DOI: 10.1016/s0040-4020(01)98968-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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β-Thioxoketones. Part 6. Electronic absorption spectra of aromatic β-thioxoketones. A study of enol–enethiol tautomerism. ACTA ACUST UNITED AC 1980. [DOI: 10.1039/p29800001768] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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On hydrogen bonding in the intramolecularly chelated tautomers of enolic malondialdehyde and its mono- and dithio-analogues. ACTA ACUST UNITED AC 1980. [DOI: 10.1039/p29800001080] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The Electronic Structure of Propyl 3-Mercaptocrotonate Studied by Photoelectron Spectroscopy. ACTA ACUST UNITED AC 1980. [DOI: 10.3891/acta.chem.scand.34b-0695] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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β-Thioxo-ketones. Part 5. Photo-induced enol–enethiol interconversion of β-thioxo-ketones. ACTA ACUST UNITED AC 1979. [DOI: 10.1039/p29790001532] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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β-Thioxo-esters. Part III. The spontaneous intramolecular cyclization of tautomeric diethyl thioacetylsuccinate. Preparation and tautomerism of 4-ethoxycarbonyl-5-methylthiophen-2(3H)-one. ACTA ACUST UNITED AC 1978. [DOI: 10.1039/p19780000292] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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