- Episulfidation of trans-Cyclooctene with an 1,2,4-Oxadithiolane
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The dipolar cycloaddition of thiobenzophenone S-oxide (1) and 2,2,4,4-tetramethyl-3-thioxocyclobutanone (2) generates the labile 1,2,4-oxadithiolane I, which in the presence of trans-cyclooctene (3) affords trans-episulfide (9). In this direct sulfur tran
- Adam, Waldemar,Bargon, Rainer M.,Mloston, Grzegorz
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- Unexpected products from the reaction of 2,2,4,4-tetramethylcyclobutane- 1,3-dione with the Makosza reagent
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Reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione (2) under phase- transfer-catalysis (PTC) conditions (CHCl3/aqueous NaOH) yielded a complex mixture of unexpected products (Scheme 2). From the organic phase, three ring-enlarged products 7-9 with a cyclopentane-1,3-dione (cf- 7 and 9) or a cyclopentenone skeleton (cf. 8) were isolated in low yield. After acidification of the aqueous phase, the oily residue was treated with CH2N2, and methyl 3-oxopentanoate 12 and dimethyl 2-hydroxybutanedioate 13 were obtained in almost equal amounts. The structures of 8 and 9 were established by X-ray crystal-structure analysis (Fig.). Mechanisms for the formation of the products, initiated by nucleophilic attack of trichloromethanide ion and opening of the cyclobutane ring, are proposed in Schemes 3 and 4.
- Mloston, Grzegorz,Romanski, Jaroslaw,Linden, Anthony,Heimgartner, Heinz
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- Preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol
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The invention discloses a preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanediol, which comprises the following steps: dissolving isobutyryl chloride in a first organic solvent, adding triethylamine and zinc powder while stirring, heating to reflux, reacting, cooling, filtering, washing, and carrying out reduced pressure distillation to obtain a distillation substrate; and dissolving the distillation substrate in a second organic solvent, cooling, filtering, introducing hydrogen under the action of a catalyst, and carrying out a reaction to obtain the product. According to the method, on the basis of the process of the BASF company, after triethylamine hydrochloride is formed by triethylamine serving as an acid-binding agent, triethylamine is released from the triethylamine hydrochloride by using proper metal, so that the triethylamine serving as the acid-binding agent can be recycled, and the triethylamine only plays a role of a bridge in a system; through continuous exchange and circulation of a small amount of triethylamine, the reaction is carried out until the reaction is complete.
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Paragraph 0014; 0027-0028; 0030-0031; 0033-0034; 0036-0037
(2021/03/11)
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- The fluoride anion-catalyzed sulfurization of thioketones with elemental sulfur leading to sulfur-rich heterocycles: First sulfurization of thiochalcones ?
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Fluoride anion was demonstrated as a superior activator of elemental sulfur (S8) to perform sulfurization of thioketones leading to diverse sulfur-rich heterocycles. Due to solubility problems, reactions must be carried out either in THF using tetrabutylammonium fluoride (TBAF) or in DMF using cesium fluoride (CsF), respectively. The reactive sulfurizing reagents are in situ generated, nucleophilic fluoropolysulfide anions FS(8?x)?, which react with the C=S bond according to the carbophilic addition mode. Dithiiranes formed thereby, existing in an equilibrium with the ring-opened form (diradicals/zwitterions) are key-intermediates, which undergo either a step-wise dimerization to afford 1,2,4,5-tetrathianes or an intramolecular insertion, leading in the case of thioxo derivatives of 2,2,4,4-tetramethylcyclobutane-1,3-dione to ring enlarged products. In reactions catalyzed by TBAF, water bounded to fluoride anion via H-bridges and forming thereby its stable hydrates is involved in secondary reactions leading, e.g., in the case of 2,2,4,4-tetramethyl-3-thioxocyclobutanone to the formation of some unexpected products such as the ring enlarged dithiolactone and ring-opened dithiocarboxylate. In contrast to thioketones, the fluoride anion catalyzed sulfurization of their α,β-unsaturated analogues, i.e., thiochalcones is slow and inefficient. However, an alternative protocol with triphenylphosphine (PPh3) applied as a catalyst, offers an attractive approach to the synthesis of 3H-1,2-dithioles via 1,5-dipolar electrocyclization of the in situ-generated α,β-unsaturated thiocabonyl S-sulfides. All reactions occur under mild conditions and can be considered as attractive methods for the preparation of sulfur rich heterocycles with diverse ring-size.
- Bielinski, Dariusz M.,Heimgartner, Heinz,Mloston, Grzegorz,Urbaniak, Katarzyna,Wreczycki, Jakub
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- Tetramethylcyclobutanedione and tetramethylcyclobutane diol Method for manufacturing the same
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The invention provides tetramethylcyclobutanedione and tetramethylcyclobutane diol, and a manufacturing method thereof. The present invention provides the following method. 2, 2, 4, 4 - Tetramethylcyclobutane -1, 3 - diketones can be easily produced by carrying out the dimerization reaction of the dimethylketene in a solvent suitable for the actual production (reaction time) by easily treating and general low boiling solvent in the production process. The dimerization reaction of the dimethyl ketene can be accelerated, and the time required for solvent removal can be shortened as compared with the high-boiling solvent. Compared with the prior art, the manufacturing can be performed in a short time.
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Paragraph 0043-0074
(2021/09/29)
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- PROCESS FOR PREPARING 2,2,4,4-TETRAMETHYL-1,3-CYCLOBUTANEDIOL
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The present invention refers to 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year a number bath method disclosure as follows. the method (A) meta acrylic acid (methacrylic acid, MAA) removed from the raw material (B) use as an intermediate in the mote [lik [lik] it buys [...] (isobutyric acid, IBA), 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol [...] (C) dimethyl ketene (dimethyl Ketene, DMK) and (D) (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanedione, CBDK) via a final material sequentially (E) 2, 2, 4, 4 - tetramethyl bhutan d this year cycle - 1, 3 - (2, 2, 4, 4 a-tetramethyl-a 1, 3 non-cyclobutanediol, CBDO) bath a number comprise substrate. According to the present invention number bath step optimization and a green protective environmental 2, 2, 4, 4 - tetramethyl - 1, 3 - cyclohexanedimethanol bhutan d this year through mirror number is encoded number bath method is highly lipophilic ball number. (by machine translation)
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Paragraph 0094; 0095
(2019/10/22)
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- PROCESS FOR PREPARING 2,2,4,4-TETRAMETHYL-1,3-CYCLOBUTANEDIOL
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Disclosed is a method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol, which prepares (E) 2,2,4,4-tetramethyl-1,3-cyclobutanediol (CBDO) which is a final material by sequentially going through (A) methacrylic acid (MAA) as a raw material, and (B) isobutyric acid (IBA), (C) isobutyric anhydride (IBAN), and (D) 2,2,4,4-tetramethyl-1,3-cyclobutanedione (CBDK) as an intermediate. According to the present invention, the method for preparing 2,2,4,4-tetramethyl-1,3-cyclobutanediol which is economical and eco-friendly by optimizing preparation steps and maximizing the efficiency is provided.COPYRIGHT KIPO 2019
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Paragraph 0119-0159
(2019/10/08)
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- Method for synthesis of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione
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The invention belongs to the technical field of organic compound preparation and discloses a preparation method of 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione. The preparation method comprises that isobutyric acid or isobutyric anhydride undergoes a cracking reaction according to a volume ratio of isobutyric acid or isobutyric anhydride to inert gas of 1: 10 to 1: 5 in a fixed bed pyrolysis reactor to produce dimethyl ketene and the dimethyl ketene directly undergoes a polymerization reaction in the solution in the same polymerization reactor to produce 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione. The method optimizes a 2, 2, 4, 4-tetramethyl-1, 3-cyclobutanedione preparation process, realizes direct polymerization of cracking products, reduces a device investment, is free of a washing tower or an absorbing tower and prevents consumption of a lot of an absorption liquid and a loss of energy. Through above characteristics, compared with the existing competitive industrial methods, the method provided by the invention has better flexibility.
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Paragraph 0044-0045
(2017/04/11)
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- Polyester from dimethylketene and acetaldehyde: Direct copolymerization and β-lactone ring-opening polymerization
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Two ways to obtain aliphatic polyesters (PEs) from dimethylketene and acetaldehyde were investigated. On the one hand, a direct anionic copolymerization was carried out in toluene at -60 °C. The resulting polymer was mainly composed of PE units. On the other hand, a two-step process involving the synthesis of 3,3,4-trimethyl-2-oxetanone by [2+2] cycloaddition, followed by its ring-opening polymerization, with various initiators and solvents, led to the expected PE. Molecular weights up to 9000 g mol -1 (measured by nuclear magnetic resonance (NMR)), with narrow polydispersity around 1.2, were obtained. These polymers were found stable up to 274 °C under nitrogen and a broad and complex endothermic peak attributed to crystallinity was observed near 139 °C by differential scanning calorimetry (DSC). The crystallinity, measured by X-ray diffraction, was close to 0.45.
- Brestaz, Marc,Desilles, Nicolas,Le, Guillaume,Bunel, Claude
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experimental part
p. 4129 - 4138
(2012/07/13)
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- Photochemical formation and reactivities of substituted oxathiiranes in low-temperature argon matrices
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Thiocarbonyl S-oxides (sulfines) derived from aliphatic and cycloaliphatic thioketones were irradiated in argon matrices at 10 K, and the resulting oxathiiranes were identified by comparison of computed and experimental IR spectra. Upon photolysis at 10 K, depending on the substitution pattern, the oxathiiranes underwent either H-shift reactions or regioselective ring enlargements to form the corresponding thioesters. After warming of the matrix material to 38-40 K, the oxathiiranes underwent fast desulfurization to yield the corresponding ketones. Density functional theory (DFT) computations at the B3LYP/6-311+G(3df,3pd) level suggest that the desulfurizations of oxathiiranes occurred as bimolecular processes with activation enthalpies near 0 kcal mol-1.
- Reisenauer, Hans Peter,Mloston, Grzegorz,Romanski, Jaroslaw,Schreiner, Peter R.
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p. 6269 - 6275
(2011/12/02)
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- Synthesis of new imidazole 3-oxides; unexpected deoxygenation of some derivatives in the reaction with 2,2,4,4-tetramethylcyclobutane-1,3-dithione
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Whereas the reaction of a series of 1,4,5-trisubstituted imidazole 3-oxides with 2,2,4,4-tetramethylcyclobutane-1,3-dithione gave the corresponding imidazole-2-thiones by a sulfur-transfer reaction via [2+3] cycloaddition, an unexpected deoxygenation occurred in the case of 4-acetyl-1-(adamantan-1-yl)- 5-methylimidazole 3-oxide. It was shown that the presence of an electronwithdrawing substituent at C(4) and the bulky 1-adamantyl group at N(1) are necessary to enable this reaction course. A reaction mechanism via a zwitterion, followed by a 1,3-cyclization and elimination of an oxathiirane, is proposed.
- Mloston, Grzegorz,Jasinski, Marcin,Rygielska, Dorota,Heimgartner, Heinz
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experimental part
p. 765 - 776
(2011/05/12)
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- Evolution of a synthetic strategy: Total synthesis of (±)- welwitindolinone A isonitrile
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An efficient and highly stereoselective total synthesis of the natural product (±)-welwitindolinone A isonitrile (1) is described. The bicyclo[4.2.0]octane core of 1 was established by a regio- and diastereoselective [2+2] ketene cycloaddition. The C12 quaternary center and vicinal stereogenic chlorine were installed in a single operation with excellent stereocontrol via a chloronium ion mediated semipinacol rearrangement. Described strategies for construction of the spiro-oxinole include a Sml 2-LiCl mediated reductive cyclization and a novel anionic cyclization that simultaneously constructs the spiro-oxindole and vinyl isonitrile moieties.
- Reisman, Sarah E.,Ready, Joseph M.,Weiss, Matthew M.,Hasuoka, Atsushi,Hirata, Makoto,Tamaki, Kazuhiko,Ovaska, Timo V.,Smith, Catherine J.,Wood, John L.
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p. 2087 - 2100
(2008/09/20)
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- Synthesis of 1,2,4-Trithiolanes from Thione S-Oxides and Lawesson Reagent at Room Temperature
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The reaction of 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-oxide with Lawesson reagent (L. R.) afforded the corresponding 1,2,4-trithiolane. Thiopivalophenone and thiopivalophenone S-oxides reacted with L. R. at rt to give the corresponding S-sulfide, which further reacted with thiones to afford the corresponding cis-1,2,4-trithiolanes.
- Okuma, Kentaro,Shigetomi, Toshiyuki,Shibata, Shinji,Shioji, Kosei
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p. 187 - 188
(2007/10/03)
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- Process for producing 2,2,4,4-tetra-substituted 1,3,5-cyclohexanetriones
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Process for the preparation of 2,2,4,4-tetrasubstituted 1,3,5-cyclohexanetriones of the formula I, by reaction of a cyclobutane-1,3-dione of the formula II with an O or N nucleophile and a silylating reagent, and subsequent acetylation and cyclization.
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- Interception of an Intermediate Thiocarbonyl Ylide by NH-Compounds
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By thermal decomposition of 1,1,3,3-tetramethyl-5-thia-7,8-diazaspiro[3.4] octan2-one (1), 2,2,4,4-tetramethyl-3-thioxocyclobutanone S-methylide (2) was generated as an intermediate. This reactive "thiocarbonyl ylide" was trapped by protic agents such as alcohols, NH- and SH-acidic compounds to give 1,3-adducts of the acetal type. In a mixture of methanol and ammonia, the spiroheterocycle 1 was deprotonated and competitive ring opening of the 2,5-dihydro-1,3,4-thiadiazole and the cyclobutane ring occurred to give the hydrazono derivative 7 and the 1,3,4-thiadiazole 8, respectively. Surprisingly, 2 was intercepted by maleimide in a 1,3-dipolar cycloaddition.
- Mloston,Janicka,Woznicka,Linden,Heimgartner
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p. 1805 - 1817
(2007/10/03)
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- Studies on reactions of thioketones with trimethyl(trifluoromethyl)silane catalyzed by fluoride ions
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Treatment of 2,2,4,4-tetramethylcyclobutane-1,3-dione (6) in THF with CF3SiMe3 in the presence of tetrabutylammonium fluoride (TBAF) yielded the corresponding 3-(trifluoromethyl)-3-[(trimethylsilyl)oxy]cyclobutanone 7 (Scheme 1) via nucleophilic addition of a CF3- anion at the C=O group and subsequent silylation of the alcoholate. Under similar conditions, the 'monothione' 1 reacted to give thietane derivative 8 (Scheme 2), whereas in the case of 'dithione' 2 only the dispirodithietane 9, the dimer of 2, was formed (Scheme 3). A conceivable mechanism for the formation of 8 is the ring opening of the primarily formed CF3 adduct A followed by ring closure via the S-atom (Scheme 2). In the case of thiobenzophenones 4, complex mixtures of products were obtained including diarylmethyl trifluoromethyl sulfide 10 and 1,1-diaryl-2,2-difluoroethene 11 (Scheme 4). Obviously, competing thiophilic and carbophilic addition of the CF3- anion took place. The reaction with 9H-fluorene-9-thione (5) yielded only 9,9′-bifluorenylidene (14; Scheme 6); this product was also formed when 5 was treated with TBAF alone. Treatment of 4a with TBAF in THF gave dibenzhydryl disulfide (15; Scheme 7), whereas, under similar conditions, 1 yielded the 3-oxopentanedithioate 17 (Scheme 9). The reaction of dithione 2 with TBAF led to the isomeric dithiolactone 16 (Scheme 8), and 3 was transformed into 1,2,4-trithiolane 18 (Scheme 10).
- Mloston, Grzegorz,Prakash, G. K. Surya,Olah, George A.,Heimgartner, Heinz
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p. 1644 - 1658
(2007/10/03)
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- Cycloadditions of 'thiocarbonyl ylides' with tetracyanoethylene (=ethenetetracarbonitrile): Interception of intermediates)
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Thiocarbonyl ylides (=sulfonium ylides) belong to the most nucleophilic 1,3-dipoles (high HO energy). In their reactions with tetracyanoethylene (TCNE=ethenetetracarbonitrile; low LU energy), a borderline crossing from the concerted mechanism to a two-step pathway via a 1,5-zwitterion was observed. Steric hindrance at one or both termini of the 1,3-dipole is an additional requirement. The ylides 3 and 13, set free by N2 elimination of dihydro-1,3,4-thiadiazoles, underwent electrocyclization or 1,4-H shift. Ylides 3 and 13 are bases and afforded MeOH adducts of different regiochemistry. Whereas 3 and TCNE in abs. THF at 45° furnished the (3 + 2) cycloadduct 20, a MeOH content of 0.5-5 vol-% in THF gave rise to a seven-membered lactim ether 22 and thiolane 20 in a 65:35 ratio (Scheme 4). Water (0.5-1 Vol.%) in THF led to lactam 24 and adduct 20 in the same ratio. The zwitterion 26, assumed to be the first intermediate, enters competing reactions: the irreversible ring closure to thiolane 20 and the reversible formation of a strained, cyclic seven-membered 'ketene imine' 28, Which is intercepted by MeOH or H2O. The gauche-conformation 32 of an analogous zwitterion, produced from the tetrasubstituted 'thiocarbonyl ylide' 13 with TCNE (Scheme 5), led to the thiolane derivative 35, while the anti-conformation 33 afforded the thioxo compound 5 and cyclopropane derivative 36 by intramolecular nucleophilic substitution.
- Huisgen, Rolf,Mloston, Grzegorz,Langhals, Elke
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p. 1805 - 1820
(2007/10/03)
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- INTERACTION OF ALKYLIDENE CARBENES WITH NITROSO COMPOUNDS
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The reaction of an alkylidenecarbene with 2-methyl-2-nitrosopropane results in various amides via the intermediacy of keteneimine N-oxide and aziridinone.
- Stang, Peter J.,Anderson, Gary H.
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p. 329 - 332
(2007/10/02)
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- Environment Effects on the ESR Spectrum of the Cation Radical of Dimethylketene in Low Temperature Matrices
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The cation radical of dimethylketene produced in γ-irradiated solid solutions of various halocarbons has been investigated by ESR over a temperature range from 77 K to the melting point of each matrix.The cation radical in CCl4 was stable up to about 180 K and the spectrum was well resolved to allow the determination of the anisotropic ESR parameters.In CCl2FCClF2 and CCl2FCCl2F, a series of irreversible spectral changes was observed with an increase in temperature.This process was interpreted in terms of the formation of the dimer cation.In the matrix of CCl3F, the ESR spectrum exhibited extra structure, which varied reversibly with temperature.The analyses of the spectra suggested that the cation radical in CCl3F weakly interacts with surrounding matrix molecules to form adducts.
- Fujisawa, Jun,Shimokoshi, Kazuo,Shida, Tadamasa
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p. 1267 - 1272
(2007/10/02)
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- Oxidation of 1,3-Cyclobutanedithiones and 3-Thio-1,3-cyclobutanediones by Singlet Oxygen
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Oxidation of 1,3-cyclobutanedithiones (4-6) and 3-thio-1,3-cyclobutanediones (1-3) upon direct excitation and by singlet oxygen yields the corresponding sulfines and/or ketones.Formation of ketone is believed to involve 1,2,3-dioxathietane as the intermediate.A zwitterionic peroxide resulting from the interaction of singlet oxygen with thiocarbonyl chromophore is the common intermediate for both ketone and sulfine.The variation in the product distribution among 1-6 is understood on the basis of the electronic and steric factors operating on the zwitterionic peroxide intermediate.
- Sundari, B.,Ramamurthy, V.
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p. 498 - 501
(2007/10/02)
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