- Chemoselective and odorless transthioacetalization of acetals using α-oxo-ketene dithioacetals as thiol equivalents
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Using α-oxo-ketene dithioacetals 1a as odorless thiol equivlents, an efficient and odorless transthioacetalization of acetals 2 has been developed. In the presence of MeCOCl in MeOH, the cleavage of 1a commences to generate thiols at both room and reflux temperatures, and the generated thiols then react with acetals 2 to give correspecting thioacetals 3 in good yield. This transthioacetalization is characterized by mild reaction conditions, simple procedure, good yields, and perfect chemoselectivity. It is noteworthy that only a very faint odor of thiols can be perceived during both the reaction and workup.
- Yu, Hai-Feng
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p. 1280 - 1286
(2013/04/10)
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- Silica-supported phosphorus pentoxide: A reusable catalyst for S,S-acetalization of carbonyl groups under ambient conditions
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Phosphorus pentoxide supported on silica gel (P2O 5/SiO2) efficiently acts as a highly active and reusable catalyst for cyclic and non-cyclic S,S-acetalization of a variety of carbonyl compounds under mild, solvent-free an
- Shaterian, Hamid Reza,Azizi, Kobra,Fahimi, Nafiseh
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experimental part
p. 85 - 91
(2012/01/06)
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- Silica-PCl5: A novel heterogenous catalyst for simple and efficient chemoselective protection of carbonyl compounds
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A simple, efficient and environmentally benign procedure has been developed for chemoselective protection of carbonyl compounds using the newly developed heterogeneous catalyst: Silica-PCl5. A variety of aldehydes and ketones were efficiently c
- Pandey, Lokesh Kumar,Pathak, Uma,Tank, Rekha,Mazumder, Avik
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experimental part
p. 167 - 171
(2010/07/05)
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- GaCI3- and TiCl4-catalyzed insertion of isocyanides into a C-S bond of dithioacetals
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(Chemical Equation Presented) The insertion reaction of isocyanide into a C-S bond of dithioacetals is catalyzed by GaCl3 or TiCl4 to afford thioimidates containing an a-alkylthio group. Balanced thiophilicity of these Lewis acids is
- Tobisu, Mamoru,Ito, Sana,Kitajima, Aki,Chatani, Naoto
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supporting information; body text
p. 5223 - 5225
(2009/06/18)
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- Simple, mild and efficient thioacetalization and transthioacetalization of carbonyl compounds and deprotection of thioacetals: Unique role of thiols in the selectivity of thioacetalization
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Silica supported sodium hydrogen sulfate (NaHSO4·SiO 2) has been employed for efficient thioacetalization and transthioacetalization of carbonyl compounds in CH2Cl2 at room temperature. Selectivity of thioacetalization was dependent on the thiols used for the conversion. The same catalyst was also found to be effective for deprotection of thioacetals in CH2Cl2-H2O at room temperature.
- Das, Biswanath,Ramu, Ravirala,Reddy, Majjigapu Ravinder,Mahender, Gurram
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p. 250 - 254
(2007/10/03)
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- Chemoselective thioacetalization and transthioacetalization of carbonyl compounds catalyzed by immobilized scandium(III) triflate in ionic liquids
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Immobilized scandium triflate [Sc(OTf)3] in ionic liquids has been found to be an extremely efficient and recyclable catalyst for the thioacetalization and transthioacetalization of both aromatic and aliphatic aldehydes. Significant rate acceleration and chemoselectivity was achieved by employing this catalytic system.
- Kamal, Ahmed,Chouhan, Gagan
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p. 3337 - 3340
(2007/10/03)
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- 2,4,4,6-Tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS) and bromine as efficient catalysts for dithioacetalization and oxathioacetalization of carbonyl compounds and transdithioacetalization reactions
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The use of 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), N-bromosuccinimide (NBS), and bromine as efficient catalysts for conversion of carbonyl compounds to their cyclic and acyclic dithioacetals and 1,3-oxathiolanes under mild reaction conditions are described. These catalysts are also used for efficient transdithioacetalization of acetals, diacetals, ketals, acylals, enamines, hydrazones, and oximes with high yields in the presence of thiols.
- Iranpoor, Nasser,Firouzabadi, Habib,Shaterian, Hamid Reza,Zolfigol
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p. 1047 - 1071
(2007/10/03)
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- Indium(III) chloride catalyzed efficient conversion of carbonyl compounds to 1,3-dithioacetals
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Several aldehydes and ketones were efficiently converted into their corresponding dithioacetals and 1,3-dithianes in high yields using catalytic amount of indium(III) chloride in dichloromethane.
- Yadav,Subba Reddy,Pandey, Sushil Kumar
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p. 715 - 719
(2007/10/03)
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- The synthesis of α-acetoxy sulfides and their Lewis acid-mediated reactions
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α-Acetoxy sulfides can be conveniently prepared by the reaction of dithioacetals with mercuric acetate at ambient temperature. They react with allyltrimethylsilane, enol silyl ethers, and cyanotrimethylsilane in the presence of SnCl4 to afford
- Kraus, George A.
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p. 2599 - 2602
(2007/10/02)
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- An expeditious synthesis of dithioacetals using zeolites
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A simple and efficient catalytic method for dithioacetalization of various carbonyl compounds (saturated and α,β-unsaturated aliphatic, aromatic, heteroaromatic and hindered) with ethanethiol and 1,3-propanedithiol using H-Y and H-mordenite (H-M) zeolites
- Kumar,Reddy,Singh,Pandey
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- Tellurium tetrachloride as a mild and efficient catalyst for dithioacetalization
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A variety of aldehydes and aliphatic ketones were converted into the corresponding dithioacetals at room temperature in good yields by using small amounts of tellurium tetrachloride as a mild Lewis acid catalyst.
- Tani, Hiroyuki,Masumoto, Kazunori,Inamasu, Tokuo,Suzuki, Hitomi
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p. 2039 - 2042
(2007/10/02)
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- Ionic Hydrogenation with Organosilanes under Acid-Free Conditions. Synthesis of Ethers, Alkoxysilanes, Thioethers, and Cyclic Ethers via Organosylil Iodide and Triflate Catalyzed Reductions of Carbonyl Compounds and Their Derivatives
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The general ether synthesis method based on the trialkylsilane/trialkylsilyl iodide or triflate reagent system has been extended to the syntheses of alkoxysilanes from ketones, tetrahydrofurans and tetrahydropyrans from dicarbonyl compounds, and thioethers by reductive cleavage of O-silylhemithioacetals.
- Sassaman, Mark B.,Prakash, G. K. Surya,Olah, George A.
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p. 3771 - 3780
(2007/10/02)
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- Hard Acid and Soft Nucleophile Systems. Part 11. Har-Soft Affinity Inversion: Dehalogenation of α-Halogeno Ketones with Aluminium Chloride and a Thiol
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α-Halogeno ketones have been dehalogenated with a combination of aluminium chloride and ethanethiol.The mechanism involved in deiodination and debromination differs from that of dechlorination and defluorination.A hard-hard interaction between carbonyl oxygen and aluminium chloride and a soft-soft interaction between iodine or bromine and thiol are the dominant factors for direct deiodination and debromination.In dechlorination and defluorination there is initial formation of the corresponding dithioacetal, whereby hard carbonyl oxygen is replaced by the soft sulphur atom. α-Chloro- and α-fluoro-dithioacetals then undergo dehalogenation to afford vinyl sulphide as a result both of a favourable soft-soft interaction between the sulphur atoms in the dithioacetal entity and thiol, and also a favourable hard-hard interaction between the nucleopilic chlorine or fluorine and aluminium chloride. α-Chloro- and α-fluoro-benzyl benzyl ketones afforded the dehalogenated product with concomitant 1,2-transposition of the carbonyl group.This suggests that there is an indirect path which operates competitively via a 1,2-dithio-olefin from α=halogenodithioacetals to vinyl sulphide.Addition of thiol to vinyl sulphide leads to the final product.A concept of hard-soft affinity inversion is proposed.
- Fuji, Kaoru,Node, Manabu,Kawabata, Takeo,Fujimoto, Mayumi
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p. 1043 - 1048
(2007/10/02)
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- HARD-SOFT AFFINITY INVERSION: DEHALOGENATION OF α-HALOKETONES
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Treatment of α-bromo and α-iodoketones with aluminium chloride and ethanethiol gave rise to dithioacetals of the corresponding dehalogenated ketones. α-Chloro and α-fluoro-ketones were also dehalogenated with the same reagent system through in situ hard-soft affinity inversion.
- Fuji, Kaoru,Node, Manabu,Kawabata, Takeo,Fujimoto, Mayumi
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p. 1153 - 1156
(2007/10/02)
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- TITANIUM TETRACHLORIDE, AN EFFICIENT AND CONVENIENT REAGENT FOR THIOACETALIZATION
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Aldehydes and ketones, when exposed to alkyl thiols or suitable alkane dithiols in presence of titanium tetrachloride, furnish near quantitative yields of the corresponding thioacetals.
- Kumar, Vijay,Dev, Sukh
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p. 1289 - 1292
(2007/10/02)
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- CARBON-CARBON DOUBLE BOND CLEAVAGE WITH A HARD LEWIS ACID AND ETHANETHIOL
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Double bonds activated by the electron withdrawing group(s) are cleaved with the reagent system consisting of a hard Lewis acid and ethanethiol to give dithioacetals.
- Fuji, Kaoru,Kawabata, Takeo,Node, Manabu,Fujita, Eiich
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p. 875 - 878
(2007/10/02)
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- TRIMETHYLSILYL TRIFLATE IN ORGANIC SYNTHESIS
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Trimethylsilyl triflate is a powerful silylating agent for organic compounds and acts as a catalyst which accelerates a variety of nucleophilic reactions in aprotic media.The reactions proceed via one-center, electrophilic coordination of the silyl group to hetero functional groups and exhibit unique selectivities.
- Noyori, R.,Murata, S.,Suzuki, M.
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p. 3899 - 3910
(2007/10/02)
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