- Direct anodic (thio)acetalization of aldehydes with alcohols (thiols) under neutral conditions, and computational insight into the electrochemical formation of the acetals
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A versatile protocol for the production of acetals/thioacetals by means of direct electrochemical oxidation is developed here under neutral conditions, providing (thio)acetals with good functional group tolerance and a wide scope for both aldehydes and (thio)alcohols. DFT calculations reveal that direct electron transfer from the anode plays a key role in carbonyl activation during this acid free acetalization process.
- Liu, Caiyan,Shen, Yongli,Xiao, Zihui,Yang, Hui,Han, Xue,Yuan, Kedong,Ding, Yi
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p. 4030 - 4034
(2019/08/07)
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- Solid-supported odorless reagents for the dithioacetalization of aldehydes and ketones
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A solid supported, odorless reagent for the dithioacetalization of aldehydes and ketones has been developed. The new reagent provides the dimercaptoalkane equivalent in combination with stoichiometric amounts of immobilized acid and enables the formation of dithianes and dithiolanes from aldehydes without any additives in good to very good yields with high purities. The reaction is chemoselective for aldehydes, but ketones can be reacted to the corresponding dithioketals if an additional Lewis acid such as BF3is added.
- Jung,Gr?ssle,Lütjohann,Br?se
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supporting information
p. 1036 - 1039
(2016/10/17)
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- Stereoselective approaches to the total synthesis of (6R,4′S, 6′R)-cryptofolione
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Total syntheses of cryptofolione were accomplished by two different routes via a common intermediate that underwent a cross-metathesis (CM) reaction with a vinyl lactone. The intermediate was prepared by coupling of an acyl anion equivalent with a chiral allyl epoxide synthon, or by Prins cyclization of a trans-cinnamaldehyde with a chiral homoallylic alcohol. Goniothalamin was obtained as a cross-metathesis product of the diacetate and vinyl lactone. Georg Thieme Verlag Stuttgart.
- Sabitha, Gowravaram,Reddy, S. Siva Sankara,Reddy, D. Vasudeva,Bhaskar, Vangala,Yadav, Jhillu S.
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body text
p. 3453 - 3460
(2010/11/20)
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- Catalytic carbon-sulfur bond formation by amphoteric vanadyl triflate: exploring with thia-Michael addition, thioacetalization, and transthioacetalization reactions
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A series of thiols have been examined as protic nucleophiles for Michael-type additions to α,β-unsaturated carbonyls as well as double nucleophilic condensations with aldehydes, ketones, and acetals catalyzed by amphoteric, water-tolerant vanadyl triflate under mild and neutral conditions. The newly developed C-S bond formation protocols were carried out smoothly in good to high yields in a highly chemoselective manner.
- Chen, Chien-Tien,Lin, Yow-Dzer,Liu, Cheng-Yuan
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supporting information; experimental part
p. 10470 - 10476
(2010/02/28)
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- Cleavage of 1,3-dithianes via acid-catalyzed hydrolysis of the corresponding 1,3-dithianemonooxides
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The hydrolysis of 1,3-dithianes to their parent carbonyl compounds via their corresponding monosulfoxides was systematically investigated. The oxidation of the 1,3-dithianes was carried out in high yields using tert-butyl hydroperoxide. Acid-catalyzed hydrolysis of the monosulfoxides to the carbonyl compounds was then performed in excellent yields. The cleavage reactions were monitored by gas chromatography and kinetics were investigated on substrates varying in electron density and steric requirements. Neither effect prevented high overall yields in the cleavage reaction. Georg Thieme Verlag Stuttgart.
- Krohn, Karsten,Cludius-Brandt, Stephan
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body text
p. 2369 - 2372
(2009/04/07)
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- Trichloromelamine (TCM) - Catalyzed efficient and selective thioacetalization of aldehydes and transthioacetalization of acetals and oxathioacetals under mild reaction conditions
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Trichloromelamine was used effectively as a catalyst for thioacetalization of aldehydes and transthioacetalization of acetals and oxathioacetals under mild and almost neutral reaction conditions. By this method, aldehydes, acetals, and oxathioacetals were selectively protected in the presence of ketones as their 1,3-dithiolanes or 1,3-dithianes. Copyright Taylor & Francis Group, LLC.
- Hazarkhani, Hassan
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p. 2597 - 2606
(2008/12/22)
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- Oxalic acid-promoted preparation of dithioacetals from carbonyl compounds or acetals
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This letter describes oxalic acid-promoted syntheses of dithioacetals from carbonyl compounds and thiols. Acetals are also converted into dithioacetals by the reaction with thiols under similar conditions. Copyright
- Miyake, Hideyoshi,Nakao, Yuichi,Sasaki, Mitsuru
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p. 104 - 105
(2007/10/03)
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- 1,3-Dithiane-derived alkoxyamines as one-carbon radical precursors
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A new method for the generation of C-2 centered radicals derived from 1,3-dithiane is presented. The radical precursors, 2-dialkylaminoxyl-1,3- dithianes, are readily prepared from 1,3-dithiane and stable nitroxides. Thermal reaction of 2-dialkylaminoxyl-1,3-dithianes with electron-deficient olefins affords carboaminoxylation products oroxidative addition products depending on the nitroxide used. The 2-dialkylaminoxyl-1,3-dithianes can also be used as initiators/regulators for the controlled living free radical polymerization of styrene. Georg Thieme Verlag Stuttgart.
- Herrera, Antonio J.,Studer, Armido
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p. 1389 - 1396
(2007/10/03)
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- A simple and practical synthetic protocol for thioacetalization of carbonyl compounds
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Various aldehydes and ketones are smoothly converted to the corresponding acyclic and cyclic dithioacetals in very good yields by employing catalytic amount of acetyl chloride at room temperature under solvent-free conditions. Some of the major advantages of this procedure are its mild reaction conditions, highly efficient and selective, good yields, economically cheaper and compatible in the presence of a wide variety of other protecting groups.
- Khan, Abu T.,Mondal, Ejabul
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p. 844 - 850
(2007/10/03)
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- Chemoselective thioacetalization in water: 3-(1,3-dithian-2-ylidene) pentane-2,4-dione as an odorless, efficient, and practical thioacetalization reagent
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A chemoselective thioacetalization utilizing 3-(1,3-dithian-2-ylidene) pentane-2,4-dione as a novel nonthiolic, odorless 1,3-propanedithiol equivalent catalyzed by p-dodecylbenze-nesulfonic acid in water has been developed.
- Dong, Dewen,Ouyang, Yan,Yu, Haifeng,Liu, Qun,Liu, Jun,Wang, Mang,Zhu, Jing
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p. 4535 - 4537
(2007/10/03)
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- A simple and practical synthetic protocol for acetalisation, thioacetalisation and transthioacetalisation of carbonyl compounds under solvent-free conditions
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A wide variety of carbonyl compounds can be converted smoothly to the corresponding acetals on treatment with alcohols or diols and triethyl orthoformate in the presence of a catalytic amount of (bromodimethyl)sulfonium bromide at room temperature. Similarly, various carbonyl compounds can be transformed into the corresponding dithioacetals on reaction with thiol or dithiols at room temperature by employing the same catalyst without any solvent. Moreover, O,O-acetals can also be converted into the corresponding dithioacetals under identical conditions. Some of the major advantages are mild reaction conditions, a high degree of efficiency, compatibilty with other protecting groups and the lack of solvents, particularly for thioacetalisation. In addition, no brominations occur at the double bond or α to the keto position or even in the aromatic ring under these experimental conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Khan, Abu T.,Mondal, Ejabul,Ghosh, Subrata,Islam, Samimul
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p. 2002 - 2009
(2007/10/03)
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- Entirely solvent-free procedure for the synthesis of distillable 1,3-dithianes using lithium tetrafluoroborate as a reusable catalyst
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Treatment of various types of aldehydes and ketones with 1,3-propanedithiol in the presence of a catalytic amount of lithium tetrafluoroborate at 25°C under solvent-free conditions followed by direct purification by distillation of the resulting mixture a
- Kazahaya, Kiyoshi,Tsuji, Shinya,Sato, Tsuneo
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p. 1640 - 1642
(2007/10/03)
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- Selective thioacetalization of aldehydes catalyzed by aqueous zinc tetrafluoroborate
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A wide range of cyclic dithioacetals are prepared from the corresponding aldehydes in the presence of aqueous solution of zinc tetrafluoroborate.
- Islam, Samimul,Majee, Adinath,Mandal, Tanmay,Khan
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p. 2911 - 2916
(2007/10/03)
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- Nickel(II) chloride as an efficient and useful catalyst for chemoselective thioacetalization of aldehydes
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A wide variety of acyclic and cyclic dithioacetals can be prepared chemoselectively from the corresponding aldehydes by employing a catalytic amount of nickel(II) chloride in dry CH2Cl2-MeOH (5:1) at room temperature in good yields.
- Khan, Abu T.,Mondal, Ejabul,Sahu, Priti R.,Islam, Samimul
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p. 919 - 922
(2007/10/03)
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- The First Nonthiolic, Odorless 1,3-Propanedithiol Equivalent and Its Application in Thioacetalization
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2-[2-Chloro-1-(1-chlorovinyl)allylidene]-1,3-dithiane 1 was synthesized by the chlorination of 3-(1,3)-dithianylidenepentane-2,4-dione 2 using the Vilsmeier-Haack reagent in 99% yield. As a novel nonthiolic, odorless 1,3-propane-dithiol equivalent, 1 was investigated in the thioacetalization reaction. Various types of aldehydes and ketones 3 were converted to the corresponding dithianes 4 in the presence of 1 in high yields (79-97%). Moreover, 1 exhibited obvious chemoselectivity between aldehyde and ketone in this thioacetalization reaction. A mechanism for this thioacetalization reaction is proposed.
- Liu, Qun,Che, Guangbo,Yu, Haifeng,Liu, Yingchun,Zhang, Jingping,Zhang, Qian,Dong, Dewen
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p. 9148 - 9150
(2007/10/03)
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- Highly efficient and chemoselective thioacetalization of carbonyl compounds catalyzed with aluminum trifluromethanesulfonate [Al(OTf)3]
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Aluminum trifluromethanesulfonate [Al(OTf)3] is a highly efficient and chemoselective catalyst for the thioacetalization of carbonyl compounds.
- Firouzabadi,Iranpoor,Kohmareh
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p. 167 - 173
(2007/10/03)
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- New applications of solid silica chloride (SiO2-Cl) in organic synthesis. Efficient preparation of diacetals of 2,2-bis(hydroxymethyl)-1,3-propanediol from different substrates and their transthioacetalization reactions. Efficient regeneration of carbonyl compounds from acetals and acylals
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A new application of solid silica chloride, an easily available and efficient catalyst for the preparation of diacetal of 2,2-bis-(hydroxymethyl)-1,3-propanediol from aldehydes, acetals, acylals, and oximes, is described. Transthioacetalization of diacetals of 2,2-bis-(hydroxymethyl)-1,3-propanediol into their corresponding 1,3-dithianes and 1,3-dithiolanes in the presence of silica chloride is presented. Efficient regeneration of carbonyl compounds from their corresponding acetals, ketals, diacetals, and acylals in the presence of this catalyst also is described.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
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p. 2847 - 2858
(2007/10/03)
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- Trichloroisocyanuric acid, as an industrial chemical, promotes transthioacetalization of diacetals of 2,2-bis (hydroxymethyl)-1,3-propanediol and cleavage of thioacetals
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Trichloroisocyanuric acid has been used as a mild, efficient, and new catalyst for transthioacetalization of diacetals of 2,2-bis (hydroxymethyl)-1,3-propanediol in CH2Cl2 at room temperature. A clean, easy, and general method for efficient deprotection of thioacetals to their corresponding carbonyl compounds using trichloroisocyanuric acid/silica gel and water system also is described.
- Firouzabadi, Habib,Iranpoor, Nasser,Hazarkhani, Hassan
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p. 2571 - 2577
(2007/10/03)
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- A new molecular iodine-catalyzed thioketalization of carbonyl compounds: Selectivity and scope
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A new molecular iodine-catalyzed thioketalization of carbonyl compounds has been developed.
- Samajdar, Susanta,Basu, Manas K.,Becker, Frederick F.,Banik, Bimal K.
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p. 4425 - 4427
(2007/10/03)
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- Stereoselective synthesis of kurzilactone and determination of its absolute configuration
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Both (5S,7S)- and (5R,7S)-isomers of kurzilactone were synthesized from a 'chiral epoxy-aldehyde synthon' through the coupling of an acyl anion equivalent and the dianion of acetoacetate, followed by formation of the Kawa-type lactone by cyclization and elimination. Comparing the spectral data of the synthesized and naturally occurring kurzilactone, the C(5)- and C(7)-stereogenic centers of the natural kurzilactone was assigned a corrected anti-relationship with (5R,7S)-absolute configuration.
- Jiang, Biao,Chen, Zili
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p. 2835 - 2843
(2007/10/03)
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- Highly efficient transdithioacetalization of acetals catalyzed by silica chloride
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A modified procedure for the preparation of a silica chloride with higher chloride capacity than that reported is described. Moreover, this silica chloride was found to be an effective catalyst for chemoselective and highly efficient transdithioacetalization of different classes of acetals.
- Firouzabadi, Habib,Iranpoor, Nasser,Karimi, Babak,Hazarkhani, Hassan
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p. 263 - 265
(2007/10/03)
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- Organocopper mediated conjugate addition of vinyl grignard reagent to α,β-unsaturated acylsilane
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Vinyl Grignard reagent added to trans-cinnamaldehyde in the presence of cuprous iodide to give conjugate addition product in good yield.
- Tsai, Yeun-Min
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p. 825 - 826
(2007/10/03)
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- Differentation between Carbonyls and Acetals in 1,3-Dithiane and 1,3-Dithiolane Synthesis Catalyzed by Organotin Triflates
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Carbonyls and acetals are converted to 1,3-dithianes and -dithiolanes upon treatment with 2-stanna-1,3-dithianes and -dithiolanes under catalysis by organotin triflates.In these competition reactions, various types of carbonyls and acetals are differentiated.Aldehydes react preferentially over ketones, but the preference is completely reversed in the competition reactions between the corresponding acetals and ketals.The reactivity of aliphatic aldehydes is greater than that of the acetals of aliphatic aldehydes and ketones.Conversely, an aromatic acetal is more reactive than its parent aldehyde.In the competition between aromatic and aliphatic aldehydes, the reaction of the latter predominates.However, aromatic acetals react preferentially over aliphatic acetals.Ketones of different types are also differentiated.No such discrimination can be achieved by conventional methods.Organotin triflates are capable of detecting subtle differences in the reactivity of carbonyls and acetals.Such unique differentiation can be explained in terms of the dependence of the reaction path on the substrate: the reactions of carbonyls are initiated by coordination to tin, whereas the reactions of acetals proceed via oxocarbenium ion intermediates.
- Sato, Tsuneo,Otera, Junzo,Nozaki, Hitosi
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p. 4971 - 4978
(2007/10/02)
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- The addition of Organolithiums to Ketenethioacetals: A new cyclopentannulation sequence leading to indanes
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A new cyclopentannulation sequence leading to the rapid preparation of highly substituted indanes e.g. (3) is described. This novel cyclisation protocol is effected via the initial union of an aryl bromide such as (1) with a 2-lithio-2-vinyl-1,3-dithiane e.g. (2) leading to a ketenethioacetal e.g. (4) Transmetallation to the corresponding aryllithium e.g. (5), by addition of an alkyllithium reagent, next effects an intramolecular 5-exo-trig cyclisation onto the ketenethioacetal moiety, leading to an indane intermediate, e.g. (6) Subsequent in situ alkylation of this intermediate (6), with the alkylbromide generated as a consequence of transmetallation, then completes the sequence.
- Harrowven, David C.
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p. 2879 - 2882
(2007/10/02)
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- HYDROLYSIS OF KETOL TRIMETHYLENEDITHIOACETALS. ATTEMPTED SYNTHESIS OF YASHABUSHIKETOL
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Thallium(III) trifluoroacetate has been shown to cleave dithianes which contain hydroxy functions that other reagents fail.Hydrolysis of a direct precursor of yashabushiketol led to tetrahydro-γ-pyrones, however.
- Ho, Tse-Lok,Hill, Raymond J.,Wong, C. M.
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p. 1719 - 1726
(2007/10/02)
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- Reactions of 1,3-Dithiolan-2-ylium and 1,3-Dithian-2-ylium Tetrafluoroborates and Ambident 2-Styryl Derivatives
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The ambident 2-styryl-1,3-dithiolan-2-ylium and 2-styryl-1,3-dithian-2-ylium cations react with preferential carbon-carbon bond formation at the β ethylenic carbon when treated with methylmagnesium iodide.In the lithium aluminium hydride reaction, reduction occurs at either electrophilic carbon center.Methanol and thiophenol react selectively with the β carbon of the side chain.The adduct formation with the heteroatom nucleophiles is readily reversed by acid catalysis.In the absence of the styryl group, the nucleophilic addition is at C-2.Dithioketals of symmetric 1,2-divarbonyl derivatives are readily formed by zinc-induced reductive dimerization of 1,3-dithiolan- and 1,3-dithian-2-ylium salts.
- Klaveness, Jo,Rise, Frode,Undheim, Kjell
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p. 373 - 380
(2007/10/02)
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