- Highly ordered mesoporous functionalized pyridinium protic ionic liquid framework as a highly efficient catalytic system in chemoselective thioacetalization of carbonyl compounds under solvent-free conditions
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Dithioacetals are a well-known class of organic compounds as both protecting group for the carbonyl compounds and valuable synthons for organic synthesis. Polysiloxane acidic ionic liquids containing pyridinium trifluoroacetate salts (PMO-Py-IL) as organi
- Karimi, Nafiseh,Luque, Rafael,Rajabi, Fatemeh,Voskressensky, Leonid
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- Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
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Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
- Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
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p. 14177 - 14183
(2021/08/16)
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- An expedient carbon–sulfur bond formation explored through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds
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A facile carbon–sulfur bond formation was observed through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds. In a preliminary study, the synthesis and characterization of functionalized bio-polymer, cellulose sulph
- Kadam, Kailas R.
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p. 530 - 541
(2020/07/03)
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- Visible-light mediated facile dithiane deprotection under metal free conditions
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Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.
- Dharpure, Pankaj D.,Bhowmick, Anindita,Warghude, Prakash K.,Bhat, Ramakrishna G.
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- Mild Deprotection of Dithioacetals by TMSCl/NaI Association in CH3CN
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A mild process using a combination of TMSCl and NaI in acetonitrile is used to regenerate carbonyl compounds from a variety of dithiane and dithiolane derivatives. This easy to handle and inexpensive protocol is also efficient to deprotect oxygenated and mixed acetals as 1,3-dioxanes, 1,3-dioxolanes and 1,3-oxathianes quantitatively. As a possible extension of this method, it was also shown that nitrogenated substrates such as hydrazones, N-tosylhydrazones, and ketimines reacted well under these conditions to give the expected ketones in high yields. The methodology proposed herein is a good alternative to the existing methods since it does not use metals, oxidants, reducing agents, acidic or basic media, and keto-products were obtained in high to excellent yields.
- Yao, Yunxin,Zhao, Guangkuan,Hamze, Abdallah,Alami, Mouad,Provot, Olivier
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p. 5775 - 5779
(2020/08/17)
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- Super electron donor-mediated reductive desulfurization reactions
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The desulfurization of thioacetals and thioethers by a pyridine-derived electron donor is described. This methodology provides efficient access to the reduced products in high yields and does not require the use of transition-metals, elemental alkali-metals, or hydrogen atom donors.
- Nozawa-Kumada, Kanako,Ito, Shungo,Noguchi, Koto,Shigeno, Masanori,Kondo, Yoshinori
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supporting information
p. 12968 - 12971
(2019/11/05)
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- Mesoporous sBa-15 silica catalyst functionalized with phenylsulfonic acid groups (SbA-15-ph-So3h) as efficient nanocatalyst for chemoselective thioacetalization of carbonyl compounds
-
In this research a Nano acidic catalyst was prepared and its efficiency on thioacetalization of carbonyl compounds was examined. For this aim we used modified SBA-15 as support, which have been modified by phenolic and sulfonic acid. SBA-15 is a member of
- Sedrpoushan, Alireza,Ghazizadeh, Habibollah
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p. 112 - 118
(2017/01/18)
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- Thioacetalization of aldehydes and ketones catalyzed by hexabromoacetone
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Protection of p-anisaldehydewith 1,3-propanedithiol under UV irradiation without a catalyst resulted in 87% yield of 1,3-dithiane in 20 min. Addition of hexabromoacetone further reduced the reaction time and UV irradiation also accelerated the formation o
- Chaiseeda, Kittichai,Chavasiri, Warinthorn
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p. 1034 - 1039
(2017/09/08)
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- Alcohol-mediated direct dithioacetalization of alkynes with 2-chloro-1,3-dithiane for the synthesis of Markovnikov dithianes
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An alcohol-mediated dithioacetalization process that gains direct access to the corresponding Markovnikov-selective 1,3-dithianes using unactivated alkynes and nonthiolic/odorless 2-chloro-1,3-dithiane in a highly efficient manner has been developed. This methodology has the advantage of having mild reaction conditions, and the dithioacetalization process gives good to excellent yields with high Markovnikov-selectivity.
- Liu, Teng,Tian, Lixia,Lai, Junshan,Min, Deng,Qu, Mengnan,Tang, Shouchu
-
supporting information
p. 4068 - 4071
(2017/07/10)
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- A substituted -1,3-dithiane-preparation method of compound
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The invention discloses a method for preparing substituted-1,3-dithiane compounds. The method comprises the following steps: 1. with 1,2-dichloroethane or dichloromethane as a solvent, stirring to react 2-chlor-1,3-dithiane with alkynes with a general formula I for 1-24 hours at a temperature condition of 45-80 DEG C in the presence of an acid medium and alcoholic compounds; 2. removing the solvent in the reaction system by rotary evaporation after the reaction, and separating and purifying the residues by column chromatography to obtain substituted-1,3-dithiane compounds with a general formula II. According to the method disclosed by the invention, the 2-chlor-1,3-dithiane directly reacts with different types of alkynes, thereby not only avoiding the defects of foul smell, strong volatility and toxicity when 1,3-propanedithiol is used, but also being safe in operation and environmental friendly, and the method has the advantages of mild reaction conditions, simple operation, high yield, etc.
- -
-
Paragraph 0036-0040
(2017/01/31)
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- Sulfonated polyanthracene-catalyzed highly efficient and chemoselective thioacetalization of carbonyl compounds and transthioacetalization of acetals and acylals
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A straightforward and highly efficient procedure for the thioacetalization of a variety of aldehydes and transthioacetalization of acylals and acetals in good to excellent yields using catalytic amounts of sulfonated polyanthracene (S-PAT) is reported. Th
- Fahid,Pourmousavi
-
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- Silica-gel supported sulfamic acid (SA/SiO2) as an efficient and reusable catalyst for conversion of ketones into oxathioacetals and dithioacetals
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A simple and efficient method for the conversion of carbonyl compounds to oxathioacetals and dithioacetals using SA/SiO2 as an acid catalyst has been achieved. SA/SiO2 is easily recovered from the reaction mixture and can be reused at least 15 times without loss of catalytic activity.
- Aoyama, Tadashi,Suzuki, Toshihiko,Nagaoka, Takashi,Takido, Toshio,Kodomari, Mitsuo
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p. 553 - 566
(2013/01/15)
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- Aluminum hydrogen sulfate [Al(HSO4)3] as an efficient catalyst for the preparation of thioacetals
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Aluminum hydrogen sulfate, as a heterogeneous solid acid catalyst, has been used for the mild conversion of carbonyl compounds to their thioacetals using 1,2- and 1,3-dithiol under ambient conditions with short reaction times in high to excellent yield in
- Ghashang, Majid
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p. 2837 - 2842
(2013/07/26)
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- Silica phenyl sulfonic acid as a solid acid heterogeneous catalyst for chemoselective thioacetalization of carbonyl compounds and dethioacetalization under mild conditions
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Silica phenyl sulfonic acid (SPSA) is an effective catalyst for chemoselective thioacetalization of aldehydes in the presence of ketones under neutral conditions. In addition, a simple and an efficient procedure for deprotection of 1,3-dithianes and 1,3-dithiolanes of aromatic, aliphatic, and α,β-unsaturated aldehydes and ketones in the solvent-free to the corresponding parent carbonyl compounds was successfully carried out with SPSA in excellent yields.
- Veisi, Hojat,Sedrpoushan, Alireza,Zolfigol, Mohammad Ali,Mohanazadeh, Farajollah,Hemmati, Saba
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p. E204-E206
(2013/06/04)
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- Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system
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The combination of 1,4-benzoquinone and a catalytic amount of NaI was found to be effective for the deprotection of dithioacetals. The reactions proceeded efficiently under mild, near-neutral reaction conditions, producing a wide range of aryl and alkyl aldehydes and ketones generally in high yields with good functional group compatibility. The method developed therefore represents a general, facile, and highly applicable approach for deprotecting dithioacetals.
- Inamoto, Kiyofumi,Yamada, Tetsuya,Kato, Sei-Ichi,Kikkawa, Shoko,Kondo, Yoshinori
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p. 9192 - 9199
(2013/10/01)
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- 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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- 2-(3,5-Dinitrophenyl)-1,3-dithiane carbanion: A benzylic anion with a low energy triplet state
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Calculations at the DFT level predict that benzyl anions with strong π-electron-withdrawing groups in the meta position(s) have low energy diradical or triplet electronic states. Specifically, the 2-(3,5-dinitrophenyl)- 1,3-dithiane carbanion is predicted
- Perrotta, Raffaele R.,Winter, Arthur H.,Coldren, William H.,Falvey, Daniel E.
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supporting information; scheme or table
p. 15553 - 15558
(2011/11/13)
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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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- Preyssler-type heteropoly acid: A new, mild and efficient catalyst for protection of carbonyl compounds
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Preyssler-type heteropoly acid is introduced as a new, mild and efficient catalyst for protection of a variety of carbonyl compounds with 1,3-propane dithiol.
- Rahimizadeh, Mohammad,Bazazan, Tahmineh,Shiri, Ali,Bakavoli, Mehdi,Hassani, Hassan
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experimental part
p. 435 - 438
(2012/01/03)
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- Dithioacetalization of carbonyl compounds under catalyst-free condition
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Protection of carbonyl compounds with 1,3-propanedithiol under a catalyst-free condition in nitromethane as a solvent has been described.
- Akhlaghinia, Batool,Makarem, Ata
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scheme or table
p. 575 - 581
(2012/04/23)
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- Synthesis and deprotection of 1,3-Dithianes and 1,3-Dithiolanes by polyphosphoric acid
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A simply, mild and efficient method for the deprotection of 1,3-dithianes and 1,3-dithiolanes to their corresponding carbonyl compounds using a mixture of polyphosphoric acid and acetic acid at 20-45 °C is reported.
- Jin, Yong-Sheng,Zhang, Wei,Zhang, Da-Zhi,Qiao, Li-Ming,Wu, Qiu-Ye,Chen, Hai-Sheng
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scheme or table
p. 1117 - 1119
(2011/12/16)
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- Reactivity of 2-aryl-1,3-dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an SRN1 mechanism
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The reactions of 2-(4-Z-phenyl)-1,3-dithiane anions (Z=H, OMe, Cl, CN) with neopentyl, neophyl and phenyl iodides were studied in DMSO, taking into consideration the effect of the Z substituent on the dithiane anions reactivity as well as on the product distribution. These substitution reactions proceed by an SRN1 mechanism with radicals and radical anions as intermediates. Two competitive pathways are possible for the radical anion of the substitution product, namely electron transfer (ET) to the substrate giving the substitution product and C-S bond fragmentation to yield a distonic radical anion. ET is the main pathway for the reactions between dithiane anions bearing electron-donor substituents and neopentyl or its analogue iodides affording the substitution products in moderate yields (41-53%). Copyright
- Oksdath-Mansilla, Gabriela,Penenory, Alicia B.
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p. 1136 - 1143
(2012/03/10)
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- Chemoselective (trans)thioacetalization of carbonyl compounds with a reusable lewis acid-surfactant-combined copper bis(dodecyl sulfate) catalyst in water
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A Lewis acid-surfactant-combined copper bis(dodecyl sulfate) [Cu(DS) 2] catalyst served as an efficient and reusable catalyst for the thioacetalization and transthioacetalization of carbonyl compounds and O,O-acetals in water at room temperature. Some of the major advantages of this procedure are high chemoselectivity, ease of operation and purification without any organic solvent, and high yields. Georg Thieme Verlag Stuttgart.
- Weng, Shiue-Shien,Chang, Shen-Chun,Chang, Tsuan-Hao,Chyn, Jong-Pyng,Lee, Shu-Wei,Lin, Chao-An,Chen, Fong-Kuang
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experimental part
p. 1493 - 1499
(2010/10/03)
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- 1,3-dibromo-5,5-dimethylhydantoin (DBH) as a mild and efficient catalyst for chemoselective thioacetalization of carbonyl compounds and dethioacetalization under mild conditions
-
Hydantoin bromide is an effective catalyst for chemoselective thioacetalization of aldehydes in the presence of ketones under neutral conditions. In addition, a simple and efficient procedure for the deprotection of 1,3-dithianes and 1,3-dithiolanes of ar
- Veisi, Hojat,Amiri, Mostafa,Hamidian, Amir Hossein,Malakootikhah, Javad,Fatolahi, Leila,Faraji, Alireza,Sedrpoushan, Alireza,Maleki, Behrooz,Saremi, Shokufe Ghahri,Noroozi, Mohammad,Bahadoori, Fatemeh,Veisi, Somayeh
-
experimental part
p. 689 - 696
(2010/06/19)
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- Catalytic carbon-sulfur bond formation by amphoteric vanadyl triflate: exploring with thia-Michael addition, thioacetalization, and transthioacetalization reactions
-
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
-
supporting information; experimental part
p. 10470 - 10476
(2010/02/28)
-
- Ferric hydrogensulfate as effective and recyclable catalyst for mild dithioacetalization of aldehydes and ketones
-
Ferric hydrogensulfate has been found to be an extremely efficient and recyclable heterogeneous catalyst for dithioacetalization reactions. Carbonyl compounds have been successfully converted into their corresponding dithiolanes and dithianes derivatives
- Shaterian, Hamid Reza,Ahmadian, Hamid Reza,Ghashang, Majid,Doostmohammadi, Razieh,Yarahmadi, Hossein
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experimental part
p. 1099 - 1108
(2009/04/07)
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- Chemoselective dithioacetalization of carbonyl compounds using magnesium hydrogensulfate as efficient heterogeneous catalyst
-
Carbonyl compounds have been successfully converted into their corresponding dithiolanes and dithianes derivatives with 1,2-ethanedithiol and 1,3-propanedithiol in excellent yield at room temperature and short reaction times using a catalytic amount of ma
- Shaterian, Hamid Reza,Hosseinian, Asghar,Ghashang, Majid,Khorami, Fahimeh
-
experimental part
p. 2490 - 2501
(2009/08/07)
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- Chemoselective dithioacetalization and oxathioacetalization of carbonyl compounds using alumina sulfuric acid as catalyst
-
Carbonyl compounds have been successfully converted into their corresponding dithiolane, dithiane, and oxathiolane derivatives using a catalytic amount of alumina sulfuric acid (Al2O3-SO3H) with excellent yields at room temperature in short reaction times under mild conditions. This simple method is a highly chemoselective procedure for protection of aldehydes in the presence of ketones, and the heterogeneous catalyst can be recovered and reused several times without any loss of its activity. Copyright Taylor & Francis Group, LLC.
- Shaterian, Hamid Reza,Hosseinian, Asghar,Ghashang, Majid
-
experimental part
p. 4097 - 4106
(2009/04/11)
-
- Regioselective transformation of alkynes into cyclic acetals and thioacetals with a gold(I) catalyst: comparison with Br?nsted acid catalysts
-
Au(I) catalyzes the transformation of alkynes into cyclic acetals and thioacetals at much higher rate than Br?nsted acids. The reaction appears to be general for a range of alkynes and diols or dithiols, which are efficiently transformed with high selectivities. One of the salient features of this reaction process is the high reactivity of the enol ether or enol thioether intermediates, which undergo a rapid isomerization reaction to afford the cyclic acetals or thioacetals, so that isolation or subsequent activation processes are not required. This type of reactions allows us to synthesize a series of fragrances.
- Santos, Laura L.,Ruiz, Violeta R.,Sabater, Maria J.,Corma, Avelino
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p. 7902 - 7909
(2008/12/21)
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- An efficient, continuous flow technique for the chemoselective synthesis of thioacetals
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By optimizing a reagent's residence time within a packed-bed reactor, it is possible to overcome selectivity issues frequently encountered in stirred reaction vessels. This important feature is demonstrated for the chemoselective protection of 4-acetylben
- Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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p. 7362 - 7365
(2008/03/13)
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- Acid-promoted thioacetalization in water using 2-(1,3-dithian-2-ylidene) malonic acid as an odorless and efficient thioacetalization reagent
-
Thioacetalization using 2-(1,3-dithian-2-ylidene)malonic acid 1 as a nonthiolic, odorless 1,3-propanedithiol equivalent promoted by p-dodecylbenzenesulfonic acid in water has been achieved. A range of selected carbonyl compounds 2 was converted into the corresponding dithioacetals 3 in high yields. Moreover, the thioacetalization showed high chemoselectivity between aldehydes and ketones. Copyright Taylor & Francis Group, LLC.
- Ouyang, Yan,Dong, Dewen,Liang, Yongjiu,Chai, Yanyan,Liu, Qun
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p. 993 - 1000
(2007/10/03)
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- Chemoselective thioacetalization using 3-(1,3-dithian-2-ylidene)pentane-2, 4-dione as an odorless and efficient propane-1,3-dithiol equivalent under solvent-free conditions
-
As a non-thiolic, odorless propane-1,3-dithiol equivalent, 3-(1,3-dithian-2-ylidene)pentane-2,4-dione has been investigated in acid-promoted thioacetalization under solvent-free conditions. A range of selected aldehydes and aliphatic ketones have been converted into the corresponding dithioacetals in high yields. The relatively slow reaction rate of aromatic ketones allowed chemoselective protection of aromatic aldehydes or aliphatic ketones, in contrast to aromatic ketones. Georg Thieme Verlag Stuttgart.
- Ouyang, Yan,Dong, Dewen,Zheng, Chunbai,Yu, Haifeng,Liu, Qun,Fu, Zhenqian
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p. 3801 - 3804
(2008/02/09)
-
- Chemoselective thioacetalization in water: 3-(1,3-dithian-2-ylidene) pentane-2,4-dione as an odorless, efficient, and practical thioacetalization reagent
-
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)
-
- A simple and practical synthetic protocol for thioacetalization of carbonyl compounds
-
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)
-
- Bismuth oxide perchlorate as a highly efficient and chemoselective catalyst for thioacetalization of carbonyl compounds under solvent-free conditions
-
Bismuth oxide perchlorate efficiently and chemoselectively catalyzes the thioacetalization of both aliphatic and aromatic carbonyl compounds under solvent-free conditions. Stearically hindered ketones are also thioacetalized in excellent yields with stoic
- Sunil Kumar,Thirupathi Reddy,Narsimha Reddy,Rao,Rajitha
-
p. 2387 - 2389
(2007/10/03)
-
- Odorless thioacetalization reagent 2-[1,3] dithian-2-ylidene-3-oxo- butanamide and its chemoselectivity
-
2-[1,3]Dithian/dithiolan-2-ylidene-3-oxo-butanamide 2a/2b were synthesized and investigated in the thioacetalization reaction of aldehydes/ketones 3. The experiments revealed that 2a could be used as a nonthiolic, odorless 1,3-propanedithiol equivalent in the conversion of aldehydes/ketones into the corresponding dithianes 4, however, 2b was less effective. Moreover, the chemoselectivity of the thioacetalization of 3 in the presence of 2a is discussed.
- Liu, Jun,Liu, Qun,Yu, Haifeng,Ouyang, Yan,Dong, Dewen
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p. 4545 - 4556
(2007/10/03)
-
- α,α-diacetyl cyclic ketene dithioacetals: Odorless and efficient dithiol equivalents in thioacetalization reactions
-
Two novel, non-thiolic, odorless dithiol equivalents, α,α- diacetyl cyclic ketene dithioacetals 2a and 2b, had been developed. A range of carbonyl compounds 3 were converted into corresponding dithioacetals, dithianes 4 and dithiolanes 5, in high yields (up to 99%) in the presence of 2a or 2b. Moreover, 2a and 2b show high chemoselectivity between aldehyde and ketone in thioacetalization.
- Yu, Haifeng,Liu, Qun,Yin, Yanbing,Fang, Qunxin,Zhang, Jingping,Dong, Dewen
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p. 999 - 1002
(2007/10/03)
-
- Chemoselective thioacetalisation and transthioacetalisation of carbonyl compounds catalysed by tetrabutylammonium tribromide (TBATB)
-
Thioacetals and thioketals of various aldehydes and ketones were obtained directly from carbonyl compounds or by a transthioacetalisation process from cyclic O,O-acetals in the presence of dithiols and a catalytic amount of tetrabutylammonium tribromide (TBATB). Chemoselective thioacetalisation of aromatic aldehydes containing an electron-donating group in the presence of an aldehyde containing an electron-withdrawing group, aldehydes in the presence of ketones, aliphatic cyclic ketones in the presence of aromatic ketones and less hindered ketones in the presence of more hindered ketones have been achieved. A cyclic acetal containing an electron-donating group has been chemoselectively transthioacetalised in the presence of an acetal having an electron-withdrawing substituent. These selectivities are due to the intrinsic reactivity of the substrate themselves and are independent of the catalyst and reaction conditions, Shorter reaction times, mild reaction conditions, stability of acid sensitive protecting groups, high efficiencies, facile isolation of the desired products and the catalytic nature of the reagent are the attractive features of the present method.
- Naik, Sarala,Gopinath, Rangam,Goswami, Mousumi,Patel, Bhisma K.
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p. 1670 - 1677
(2007/10/03)
-
- Yttrium triflate as an efficient and useful catalyst for chemoselective protection of carbonyl compounds
-
Carbonyl compounds have been successfully converted into their corresponding oxathiolane, dithiolane, and dithiane derivatives with 2-mercaptoethanol, 1,2-ethanedithiol, and 1,3-propanedithiol using catalytic amount of yttrium triflate. In addition, by us
- De, Surya Kanta
-
p. 2339 - 2341
(2007/10/03)
-
- A simple and practical synthetic protocol for acetalisation, thioacetalisation and transthioacetalisation of carbonyl compounds under solvent-free conditions
-
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)
-
- Entirely solvent-free procedure for the synthesis of distillable 1,3-dithianes using lithium tetrafluoroborate as a reusable catalyst
-
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)
-
- Highly efficient and chemoselective thioacetalization of carbonyl compounds catalyzed with aluminum trifluromethanesulfonate [Al(OTf)3]
-
Aluminum trifluromethanesulfonate [Al(OTf)3] is a highly efficient and chemoselective catalyst for the thioacetalization of carbonyl compounds.
- Firouzabadi,Iranpoor,Kohmareh
-
p. 167 - 173
(2007/10/03)
-
- 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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- Heteropoly acids as heterogeneous catalysts for thioacetalization and transthioacetalization reactions
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Heteropoly acids are effective solid catalysts for the thioacetalization of carbonyl compounds. Tungstophosphoric acid (H3PW12O40), was found to be an effective and a highly selective catalyst for the thioacetalization of aldehydes, ketones and for the transthioacetalization of acetals, acylals and O,S-acetals which proceeded in excellent yields in the absence of solvent. The catalyst has also been successfully applied to the chemoselective conversion of α- or β-diketones and a β-keto ester into the corresponding dithioacetals. Sterically hindered carbonyl compounds such as camphor and benzophenone were also converted to their corresponding thioacetals in refluxing petroleum ether in 89-94percent yields. Surprisingly, anthrone was reduced to anthracene in 91percent yield.
- Firouzabadi,Iranpoor,Amani
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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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- Neutral lithium triflate (LiOTf) efficiently catalyzes chemoselective preparations of cyclic and acyclic dithioacetals from carbonyl compounds, acylals, and O,O-cyclic and open-chain acetals under solvent-free conditions
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An efficient and chemoselective preparation of cyclic and acyclic thioacetals from carbonyl compounds, cyclic and acyclic acetals and acylals in the presence of catalytic amounts of neutral lithium triflate and thiols under solvent-free conditions is described.
- Firouzabadi, Habib,Eslami, Shahram,Karimi, Babak
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p. 2401 - 2406
(2007/10/03)
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- Trichloroisocyanuric acid as a mild and efficient catalyst for thioacetalization and transthio-acetalization reactions
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Trichloroisocyanuric acid (1), a cheap industrial chemical, catalyzes mild and efficient thioacetalization and transthioacetalization reactions. In addition, this catalyst is very selective for this purpose.
- Firouzabadi,Iranpoor,Hazarkhani
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p. 1641 - 1643
(2007/10/03)
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- Molybdenum pentachloride (MoCl5) catalyzes efficient dithioacetalization of carbonyl compounds and transdithioacetalization of O, O-acetals. This catalyst also conducts efficient non-hydrolytic deprotection of dithioacetals in the presence of dry DMSO. Part 2
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Dithioacetalization of carbonyl compounds was performed efficiently in CH2Cl2 at room temperature in the presence of MoCl5. Highly selective transdithioacetalization of acetals was also catalyzed efficiently by this catalyst. MoCl5 performed non-hydrolytic deprotection of dithioacetals in the presence of dry DMSO.
- Firouzabadi,Karimi
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p. 207 - 216
(2007/10/03)
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- An efficient procedure for the preparation of cyclic ketals and thioketals catalyzed by zirconium sulfophenyl phosphonate
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A convenient method for the preparation of cyclic ketals and thioketals using zirconium sulfophenyl phosphonate as catalyst is described.
- Curini,Epifano,Marcotullio,Rosati
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p. 1182 - 1184
(2007/10/03)
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