- An uncommon use of irradiated flavins: Br?nsted acid catalysis
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We present that thioacetalization of aldehydes can be induced by blue light irradiation in the presence of a catalytic amount of riboflavin tetraacetate (RFTA) under aerobic conditions. Several control experiments have suggested that the reaction is more
- Arakawa, Yukihiro,Mihara, Tomohiro,Fujii, Hiroki,Minagawa, Keiji,Imada, Yasushi
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- Perchloric acid adsorbed on silica gel (HClO4-SiO2) as an extremely efficient and reusable catalyst for 1,3-dithiolane/dithiane formation
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Perchloric acid adsorbed on silica gel (HClO4-SiO2) has been found to be an extremely efficient and reusable catalyst for 1,3-dithiolane and 1,3-dithiane formation under solvent-free conditions at room temperature. Georg Thieme Verla
- Rudrawar, Santosh,Besra, Ram C.,Chakraborti, Asit K.
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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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- Lithium trifluoromethanesulfonate (LiOTf) as a highly efficient catalyst for chemoselective dithioacetalization of carbonyl compounds under neutral and solvent-free conditions
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Various types of carbonyl compound can be efficiently and chemoselectively converted to their corresponding dithioacetals in the presence of catalytic amounts of lithium triflate under solvent-free conditions. Due to the neutrality of the reaction medium, this method is especially useful for acid sensitive substrates.
- Firouzabadi, Habib,Karimi, Babak,Eslami, Shahram
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- Investigations towards the chemoselective thioacetaliztion of carbonyl compounds by using ionic liquid [bmim]Br as a recyclable catalytic medium
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The ionic liquid based on the 1-n-butyl-3-methylimidazolium cation has been prepared and used as an efficient catalytic medum for the chemoselective thioacetalization of carbonyl compounds. Furthermore, recycling and reuse of this ionic liquid medium has
- Kamal, Ahmed,Chouhan, Gagan
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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
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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
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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
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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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- Highly efficient transthioacetalization of O,O-acetals catalyzed by indium(III) chloride
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A simple, efficient and general procedure has been developed for the transthioacetalization of O,O-acetals catalyzed by indium(III) chloride in 1,2-dichloroethane.
- Ranu, Brindaban C.,Das, Arijit,Samanta, Sampak
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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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- 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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- A Novel Method for Direct Conversion of Carboxylic Acids to 1,3-Dithianes by 1,3,2-Dithiaborinane-Dimethyl Sulfide and Stannous Chloride
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Reaction of carboxylic acids with 1,3,2-dithiaborinane-dimethyl sulfide in the presence of stannous chloride in tetrahydrofuran affords the corresponding 1,3-dithianes in high yields.
- Kim, Sunggak,Kim, Sung Soo,Lim, Sung Taek,Shim, Sang Chul
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- Zirconium tetrachloride (ZrCl4) catalyzed highly chemoselective and efficient transthioacetalization of acetals
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Zirconium tetrachloride (ZrCl4) is an efficient catalyst for the highly chemoselective transthioacetalization of acetals under mild reaction conditions.
- Firouzabadi, Habib,Iranpoor, Nasser,Karimi, Babak
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- A mild and efficient method for the protection of carbonyl compounds as oxathiolanes, dithiolanes and dithianes catalyzed by molybdenyl acetylacetonate
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Carbonyl compounds have been successfully converted into their corresponding oxathiolane, dithiolane and dithiane derivatives in excellent yields with 2-mercaptoethanol, 1,2-ethanedithiol and 1,3-propanedithiol using a catalytic amount of molybdenyl acety
- Rana, Kalyan Kumar,Guin, Chandrani,Jana, Samaresh,Roy, Subhas Chandra
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- Yttrium triflate as an efficient and useful catalyst for chemoselective protection of carbonyl compounds
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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
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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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- 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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- 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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- Mild and efficient chemoselective protection of aldehydes as dithioacetals employing N-bromosuccinimide
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A mild and chemoselective dithioacetalization procedure for the protection of aromatic, aliphatic, and alkenyl aldehydes in presence of catalytic amount of N-bromosuccinimide under neutral conditions is described.
- Kamal, Ahmed,Chouhan, Gagan
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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
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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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- 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
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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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- 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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- Visible-Light-Induced in Situ Generation of Fischer-Type Copper Carbene Complexes from Acylsilanes and Its Application to Catalytic [4 + 1] Cycloaddition with Siloxydienes
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A novel methodology for in situ generation of Fischer-type metal–carbene complexes was developed. Photoirradiation to a mixture of an acylsilane and a cationic copper complex cleanly gave a Fischer-type copper–siloxycarbene complex, which was detected by spectroscopic methods. This carbene complex reacted with siloxydienes in a [4 + 1] cycloaddition manner to give cyclopentene derivatives. It is noteworthy that this reaction proceeds with a catalytic amount of copper through in situ generation of a Fischer-type copper–siloxycarbene complex intermediate.
- Takeuchi, Taiichi,Aoyama, Tsukasa,Orihara, Kurumi,Ishida, Kento,Kusama, Hiroyuki
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supporting information
p. 9490 - 9494
(2021/12/14)
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- Catalytic application of sulfamic acid-functionalized magnetic Fe3O4nanoparticles (SA-MNPs) for protection of aromatic carbonyl compounds and alcohols: Experimental and theoretical studies
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Protection techniques of functional groups within the structure of organic compounds are important synthetic methods against unwanted attacks from various reagents during synthetic sequences. Acetal and thioacetal groups are well known as protective funct
- Khaef, Sepideh,Taherpour, Avat Arman,Yarie, Meysam,Zolfigol, Mohammad Ali
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p. 44946 - 44957
(2020/12/30)
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- Dehydrative Glycosylation Enabled by a Comproportionation Reaction of 2-Aryl-1,3-dithiane 1-Oxide?
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A new dehydrative glycosylation reaction has been established by capitalizing on the comproportionation reaction of 2-aryl-1,3-dithiane 1-oxides promoted by triflic anhydride (Tf2O). By wedding the high potency of thiophilic promoter system with the step efficiency of dehydrative glycosylation, this reagent underwent facile intermolecular oxothio acetalization with C1-hemiacetal donor to install a temporary leaving group, rendering a transient electrophilic center at the remote site to the anomeric position. The sulfenyl triflate tethered at the terminus concomitantly activated the sulfide intramolecularly to afford the oxocarbenium ion, thereby facilitating the title glycosylation. Aside from accommodating broad range functional groups and inactive hemiacetal substrates, the present activation protocol also proved expedient for 1,3-diol protection. Most importantly, this method further provided a fresh perspective for the application of sulfur chemistry to carbohydrate chemistry.
- Cai, Lei,Zeng, Jing,Li, Ting,Xiao, Ying,Ma, Xiang,Xiao, Xiong,Zhang, Qin,Meng, Lingkui,Wan, Qian
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supporting information
p. 43 - 49
(2019/11/28)
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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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- Anodic oxidation of dithiane carboxylic acids: A rapid and mild way to access functionalized orthoesters
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A new electrochemical methodology has been developed for the preparation of a wide variety of functionalized orthoesters under mild and green conditions from easily accessible dithiane derivatives. The new methodology also offers an unprecedented way to access tri(fluorinated) orthoesters, a class of compound that has never been studied before. This provides the community with a rapid and general method to prepare libraries of functionalized orthoesters from simple and readily available starting materials.
- Denis, Camille,Dobbs, Adrian P.,Garcia, Anthony D.,Goodall, Iain C. A.,Lam, Kevin,Leech, Matthew C.,Petti, Alessia
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supporting information
p. 4000 - 4005
(2020/06/08)
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- Synthesis of Chiral α-Aminosilanes through Palladium-Catalyzed Asymmetric Hydrogenation of Silylimines
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The asymmetric hydrogenation of silylimines was first developed by using a palladium complex of a P-stereogenic diphosphine ligand as the catalyst, affording the valuable chiral α-aminosilanes with quantitative conversions and excellent enantioselectiviti
- Fan, Dongyang,Liu, Yang,Jia, Jia,Zhang, Zhenfeng,Liu, Yangang,Zhang, Wanbin
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supporting information
p. 1042 - 1045
(2019/05/16)
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- A 2 - substituted - 1, 3 - dithiane derivative of the preparation method
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The invention provides a preparation method of a 2-substituted-1,3-dithiane derivative. The preparation method comprises the following steps: adding 1,3-dithiane (CAS:505-23-7) and 1,2-dichloroethane (DCE) or dichloromethane (DCM) into a reaction bottle, adding N-chlorosuccinimide (NCS) under ice-bath condition, and stirring for 0.5-1 h to prepare a 2-chloro-1,3-dithiane solution; and adding an aldehyde or ketone compound and a lewis acid catalyst into the above solution, and reacting to prepare the 2-substituted-1,3-dithiane derivative. By using the 1,3-dithiane solid and different types of aldehyde and keto-carbonyl compounds as raw material and using one or more of ferric trichloride, boron trifluoride diethyl etherate, methanesulfonic acid, aluminum trichloride, ferrous chloride and nickel chloride as catalysts, preparation of the 2-substituted-1,3-dithiane derivative is realized. The catalysts used in the invention are cheap and easily available, dosage of the catalysts is low and pollution of the catalysts is little. The solid raw materials used in the invention can avoid use of fetid toxic 1,3-dimercaptopropane with strong volatility, and the purpose of protecting an experimenter's body and reducing environmental pollution is realized. In addition, the preparation method has advantages of mild reaction condition, high yield, simple operation and the like.
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Paragraph 0023; 0024; 0025; 0026
(2019/06/26)
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- Visible-light promoted dithioacetalization of aldehydes with thiols under aerobic and photocatalyst-free conditions
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A novel photocatalyst-free visible-light-mediated dithioacetalization of aldehydes and thiols has been developed. This protocol is operationally simple, mild and atom-economical, which provides an environmental benign access to dithioacetals at room temperature under aerobic conditions.
- Xing, Zhimin,Yang, Mingyang,Sun, Haiyu,Wang, Zemin,Chen, Peng,Liu, Lin,Wang, Xiaolei,Xie, Xingang,She, Xuegong
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supporting information
p. 5117 - 5122
(2018/11/24)
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- Preparing method of 2-substituted-1,3-dithiane derivative
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The invention belongs to the technical field of organic synthesis, and particularly discloses a preparing method of a 2-substituted-1,3-dithiane derivative. The preparing method comprises the following steps of adding substrate aldehyde, 1,3-dimercaptopro
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Paragraph 0020-0026; 0051-0053
(2018/10/02)
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- Iminoxyl Radical-Promoted Oxycyanation and Aminocyanation of Unactivated Alkenes: Synthesis of Cyano-Featured Isoxazolines and Cyclic Nitrones
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A novel and facile approach to vicinal oxycyanation and aminocyanation of internal unactivated alkenes is developed. This method utilizes the dichotomous reactivity of iminoxyl radical derived from the initiation of β,γ- and γ,δ-unsaturated ketoximes to provide the general difunctionalization of internal alkenes using tert-butyl hydroperoxide (TBHP) as the environmentally friendly oxidant, CuCN as the commercially available cyanating reagent, and pentamethyldiethylenetriamine (PMDETA) as the ligand. By using this protocol, a series of useful cyano-featured isoxazolines and cyclic nitrones were efficiently prepared.
- Chen, Fei,Zhu, Fei-Fei,Zhang, Man,Liu, Rui-Hua,Yu, Wei,Han, Bing
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supporting information
p. 3255 - 3258
(2017/06/23)
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- Oxidative [1,2]-Brook Rearrangements Exploiting Single-Electron Transfer: Photoredox-Catalyzed Alkylations and Arylations
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Oxidative [1,2]-Brook rearrangements via hypervalent silicon intermediates induced by photoredox-catalyzed single-electron transfer have been achieved, permitting the formation of reactive radical species that can engage in alkylations and arylations.
- Deng, Yifan,Liu, Qi,Smith, Amos B.
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supporting information
p. 9487 - 9490
(2017/07/24)
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- The directing group wins over acidity: kinetically controlled regioselective lithiation for functionalization of 2-(2,4-dihalophenyl)-1,3-dithiane derivatives
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Regioselective lithiation followed by functionalization of 2-(2,4-dihalophenyl)-1,3-dithiane derivatives with different electrophiles was achieved in good to excellent yields. When the title compound is treated with n-butyl lithium, lithiation occurs selectively at the aromatic carbon having less acidic proton despite the presence of thermodynamically more acidic 1,3-dithiane proton in the same molecule. Computationally calculated pKa values of the available reactive site protons and the experimental results suggest that the regioselective lithiation in 2-(2,4-dihalophenyl)-1,3-dithiane derivatives is not governed by thermodynamic acidity rather exclusively dictated by the kinetic removal of protons due to cooperative coordination (complex induced proximity effect, CIPE) and inductive effects of the 1,3-dihalo substituents present in the aromatic ring. By employing this regioselective functionalization, diverse 1,2,3,4-tetra-substituted aromatic compounds were prepared with ease.
- Sakthivel, Shanmugam,Kothapalli, Raveendra Babu,Balamurugan, Rengarajan
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p. 1670 - 1679
(2016/02/09)
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- Rhodium(III)-catalyzed oxidative alkenylation of 1,3-dithiane-protected arenecarbaldehydes via regioselective C-H bond cleavage
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A Rh(III)-catalyzed direct alkenylation of 2-aryl-1,3-dithiane derivatives with alkenes has been developed. The 1,3-dithiane group can serve as an effective directing group for the exclusively monoselective alkenylation under mild oxidative conditions. Th
- Unoh, Yuto,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
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supporting information
p. 704 - 707
(2015/03/05)
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- Preparation of unsymmetrical ketones from tosylhydrazones and aromatic aldehydes via formyl C-H bond insertion
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Preparation of ketones by insertion of diazo compounds into the formyl C-H bond of an aldehyde is an attractive procedure, but use of structurally diverse diazo compounds is hampered by preparation and safety issues. A convenient procedure for the synthesis of unsymmetrical ketones from bench-stable tosylhydrazones and aryl aldehydes is reported. The procedure can be performed in one pot from the parent carbonyl compound and needs only a base, with no additional promoters being required.
- Allwood, Daniel M.,Blakemore, David C.,Ley, Steven V.
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supporting information
p. 3064 - 3067
(2014/06/23)
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- Synthesis of chiral α-diarylacetic esters by stereospecific 1,2-aryl migration promoted by in situ generated acetals from benzoins
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A simple protocol for the synthesis of α-diarylacetic esters from benzoins is described. In situ generated acetal assists rapid 1,2-aryl migration in a stereospecific manner, paving the way to make enantioenriched α-diarylacetic esters from easily accessi
- Kothapalli, Raveendra Babu,Niddana, Ramana,Balamurugan, Rengarajan
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supporting information
p. 1278 - 1281
(2014/04/03)
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- Fe-catalyzed direct dithioacetalization of aldehydes with 2-chloro-1,3-dithiane
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Present methods to synthesize 1,3-dithiane molecules require either harsh reaction conditions or highly specialized reagents. We have developed a catalytic dithioacetalization process that directly gains access to the corresponding 1,3-dithianes using aldehydes and 2-chloro-1,3-dithiane in a highly efficient manner. This methodology is beneficial due to mildness of the reaction conditions, and the dithioacetaliation process results in good to excellent yields by using 15 mol % of an iron catalyst.
- Lai, Junshan,Du, Wenbin,Tian, Lixia,Zhao, Changgui,She, Xuegong,Tang, Shouchu
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p. 4396 - 4399
(2015/01/08)
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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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- 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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- Mesoporous silica-functionalized dual Br?nsted acidic ionic liquid as an efficient catalyst for thioacetalization of carbonyl compounds in water
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A novel silica-functionalized dual Br?nsted acidic ionic liquid (ionic liquid with two Br?nsted acidic species) has been reported as a highly efficient catalyst for thioacetalization of carbonyl compounds. The reaction was efficiently performed in water a
- Vafaeezadeh, Majid,Dizicheh, Zahra Bahrami,Hashemi, Mohammad Mahmoodi
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- Synthetic strategy toward γ-KETO NITRILES and their Biocatalytic conversion to asymmetric γ-lactones
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Asymmetric γ-hydroxy nitriles are valuable intermediates because hydrolysis of the nitriles can result in an intramolecular cyclization to chiral γ-lactones, which have a variety of biological uses. Starting with an assortment of different aldehydes (alkyl and aryl) a 4-step synthesis of γ-keto nitriles was developed. These prochiral substrates were then screened against a library of ketoreductases for their ability to stereoselectively reduce the carbonyl. Enzymes from the short chain dehydrogenase family showed activity and these enzymatic reactions were scaled up to produce a diverse set of chiral γ-lactones.
- Franz, Sarah E.,Watkins, Richard R.,Wright, Laura A.,Weaver, Blair A.,Hartage, Ramon C.,Ghiviriga, Ion,Gumina, Giuseppe,Feske, Brent D.
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p. 2171 - 2178
(2013/08/23)
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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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- Chemoenzymatic synthesis of chiral unsymmetrical benzoin esters
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A chemoenzymatic Dynamic Kinetic Resolution (DKR) of unsymmetrical benzoins (Ar1≠Ar2) has been carried out, by using Pseudomonas stutzeri lipase stereorecognition pattern. After studying this lipase behaviour, a high preference towards acylation of those benzoins containing substituents in the phenyl ring rather than in the benzoyl moiety was observed. This fact allowed the development of the DKR process of this kind of substrates, avoiding the accumulation of secondary products derived from the in situ racemization mediated by Shvo's catalyst action, and allowing the synthesis of enantiopure unsymmetrical benzoins acetates (not previously described) in very good yields (60-95%) and excellent enantiomeric excess values (always >99%).
- Hoyos, Pilar,Pace, Vittorio,Sinisterra, José V.,Alcántara, Andrés R.
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experimental part
p. 7321 - 7329
(2011/10/09)
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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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- 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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- New synthetic strategy for high-enantiopurity N-protected α-amino ketones and their derivatives by asymmetric hydrogenation
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Asymmetric hydrogenation of α-dehydroamino ketones catalyzed by a rhodium-chiral phosphorus ligand complex (up to 99% ee, 1000 TON), represents an efficient approach to chiral α-amino ketones. The reduction of α-amino ketones catalyzed by palladium on carbon (Pd/C) leads to amphetamine precursors with quantitative yield and no significant enantioselectivity loss.
- Sun, Tian,Hou, Guohua,Ma, Miaofeng,Zhang, Xumu
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supporting information; experimental part
p. 253 - 256
(2011/04/16)
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- Synthesis of benzo[b]furans by palladium-NHC catalyzed ring closure of o-bromobenzyl ketones
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The palladium-catalyzed ring closure of aryl o-bromobenzyl ketones, easily accessible from aromatic aldehydes and 2- bromobenzyl bromide, provides a straightforward route to 2-aryl- benzofurans. A study of the ring closure revealed that a heterocyclic car
- Farago, Janos,Kotschy, Andras
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scheme or table
p. 85 - 90
(2009/06/18)
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- Chemoselective dithioacetalization of carbonyl compounds using magnesium hydrogensulfate as efficient heterogeneous catalyst
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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
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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
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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
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experimental part
p. 4097 - 4106
(2009/04/11)
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- Ferric hydrogensulfate as effective and recyclable catalyst for mild dithioacetalization of aldehydes and ketones
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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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scheme or table
p. 1099 - 1108
(2009/04/07)
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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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- A mild and chemoselective dithioacetalization of aldehydes in the presence of anhydrous copper (II) sulfate
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Various aldehydes have been protected with different thiols as dithioacetals with excellent yields using anhydrous copper sulfate as a mild and chemoselective catalyst. The reaction is carried out in a solvent and/or under solvent-free conditions. The transthioacetalization of oxyacetals into dithioacetals was also achieved in an excellent yield. Copyright Taylor & Francis Group, LLC.
- Moghaddam, Firouz Matloubi,Bardajee, Ghasem Rezanejade,Oskui, Afsane Arefi
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p. 1445 - 1450
(2007/10/03)
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- Silica-supported perchloric acid (HClO4-SiO2): A versatile catalyst for tetrahydropyranylation, oxathioacetalization and thioacetalization
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A simple and convenient synthetic protocol for the protection of hydroxyl group as tetrahydropyranyl ether as well as carbonyl functionality as oxathioacetal and thioacetal has been achieved using a catalytic amount of silica-supported perchloric acid und
- Khan, Abu T.,Parvin, Tasneem,Choudhury, Lokman H.
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p. 2497 - 2502
(2008/02/03)
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- Chemoselective thioacetalization with odorless 2-(1,3-dithian-2-ylidene)-3- oxobutanoic acid as a 1,3-propanedithiol equivalent
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Odorless 2-(1,3-dithian-2-ylidene)-3-oxobutanoic acid (1c) was prepared and investigated in the thioacetalization of carbonyl compounds as a 1,3-propanedithiol equivalent. The results showed that the thioacetalization of various carbonyl compounds 2 with 1c proceeded smoothly and afforded the corresponding dithioacetals 3 in high yields (up to 99%) in the presence of acetyl chloride at room or reflux temperatures. Moreover, the thioacetalization exhibited high chemoselectivity between aldehydes and ketones.
- Yu, Haifeng,Dong, Dewen,Ouyang, Yan,Liu, Qun
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p. 1741 - 1745
(2007/10/03)
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- Chemoselective thioacetalisation and transthioacetalisation of carbonyl compounds catalysed by tetrabutylammonium tribromide (TBATB)
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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)
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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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- Pr(OTf)3 as an efficient and recyclable catalyst for chemoselective thioacetalization of aldehydes
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Praseodymium triflate has been found to be an efficient and recyclable catalyst for chemoselective protection of aldehydes.
- De, Surya Kanta
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p. 2837 - 2840
(2007/10/03)
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- Cobalt(II)chloride catalyzed chemoselective thioacetalization of aldehydes
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A mild and chemoselective dithioacetalization procedure for the protection of various aldehydes in the presence of catalytic amount of cobalt(II)chloride is described.
- De, Surya Kanta
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p. 1035 - 1036
(2007/10/03)
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- Molten salt as a green reaction medium: Efficient and chemoselective dithioacetalization and oxathioacetalization of aldehydes mediated by molten tetrabutylammonium bromide
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Tetrabutylammonium bromide in the molten state has been demonstrated to be a very efficient catalyst and reaction medium for the highly chemoselective dithioacetalization and oxathioacetalization of aldehydes. The tetrabutylammonium bromide is recycled fo
- Ranu, Brindaban C.,Das, Arijit
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p. 605 - 608
(2007/10/03)
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