cas 24588-72-5, 4-Methoxybenzaldehyde trimethylenedithioacetal

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PhIO-Mediated oxidative dethioacetalization/dethioketalization under water-free conditions
Treatment of thioacetals and thioketals with iodosobenzene in anhydrous DCM conveniently afforded the corresponding carbonyl compounds in high yields under water-free conditions. The mechanistic studies indicate that this dethioacetalization/dethioketalization process does not need water and the oxygen of the carbonyl products comes from the hypervalent iodine reagent.
Du, Yunfei,Ouyang, Yaxin,Wang, Xi,Wang, Xiaofan,Yu, Zhenyang,Zhao, Bingyue,Zhao, Kang
p. 48 - 65
(2021/06/16)

Visible-Light Mediated Tryptophan Modification in Oligopeptides Employing Acylsilanes
A method for the selective tryptophan modification and labelling of tryptophan-containing peptides is described. Photoirradiation of acylsilanes generates reactive siloxycarbenes which undergo H?N-insertion into the indole moiety of tryptophan to give stable silyl protected hemiaminals. This method is successfully applied to chemically modify various tryptophan containing oligopeptides. The method enables the selective introduction of alkynes to peptides that are eligible for further alkyne-azide click chemistry. In addition, the dansyl fluorophore can be conjugated to a peptide using this approach.
Reimler, Jannik,Studer, Armido
supporting information
p. 15392 - 15395
(2021/10/04)

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
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
(2021/10/04)

Preparation and Application of α-Imino Ketones through One-Pot Tandem Reactions Based on Heyns Rearrangement
α-Imino ketone is a useful building block for the preparation of α-amino ketones and α-amino alcohols. However, its preparation has been seldomly seen. Herein, a metal-free and operationally simple strategy has been developed to generate α-imino ketones with high regioselectivity. Meanwhile, the method allowed for the preparation of various N,O-ketals with high regioselectivities and diastereoselectivities through cascade reactions in one pot.
Li, Ling,Zhang, Shiqi,Deng, Xiongfei,Li, Guangxun,Tang, Zhuo,Zhao, Gang
supporting information
p. 6819 - 6824
(2021/09/08)

Dehydrative Glycosylation Enabled by a Comproportionation Reaction of 2-Aryl-1,3-dithiane 1-Oxide?
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
p. 43 - 49
(2019/11/28)

Photocatalytic Reductive Radical-Polar Crossover for a Base-Free Corey–Seebach Reaction
A metal-free generation of carbanion nucleophiles is of prime importance in organic synthesis. Herein we report a photocatalytic approach to the Corey–Seebach reaction. The presented method operates under mild redox-neutral and base-free conditions giving the desired product with high functional group tolerance. The reaction is enabled by the combination of photo- and hydrogen atom transfer (HAT) catalysis. This catalytic merger allows a C?H to carbanion activation by the abstraction of a hydrogen atom followed by radical reduction. The generated nucleophilic intermediate is then capable of adding to carbonyl electrophiles. The obtained dithiane can be easily converted to the valuable α-hydroxy carbonyl in a subsequent step. The proposed reaction mechanism is supported by emission quenching, radical–radical homocoupling and deuterium labeling studies as well as by calculated redox-potentials and bond strengths.
Crespi, Stefano,Donabauer, Karsten,K?nig, Burkhard,Murugesan, Kathiravan,Rozman, Ur?a
supporting information
p. 12945 - 12950
(2020/09/23)

An expedient carbon–sulfur bond formation explored through the cellulose sulfonic acid (CSA) catalyzed dithioacetal protection of carbonyl compounds
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.
p. 530 - 541
(2020/07/03)

An uncommon use of irradiated flavins: Br?nsted acid catalysis
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
supporting information
p. 5661 - 5664
(2020/06/09)

A 2 - substituted - 1, 3 - dithiane derivative of the preparation method
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 0020; 0026

(2019/06/26)

Synthesis of Chiral α-Aminosilanes through Palladium-Catalyzed Asymmetric Hydrogenation of Silylimines
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
supporting information
p. 1042 - 1045
(2019/05/16)

Enantio-, Regio- and Chemoselective Copper-Catalyzed 1,2-Hydroborylation of Acylsilanes
Enantioselective synthesis of synthetically significant (α-hydroxyallyl)silanes, (α-hydroxyaryl)silanes, and (α-hydroxyalkyl)silanes is reported. The present copper-catalyzed 1,2-selective hydroborylation of acylsilanes affords the aforementioned products
Nagy, Audric,Collard, Laurent,Indukuri, Kiran,Leyssens, Tom,Riant, Olivier
supporting information
p. 8705 - 8708
(2019/06/13)

Nickel-Catalyzed Synthesis of Silanes from Silyl Ketones
An unprecedented nickel-catalyzed decarbonylative silylation via CO extrusion intramolecular recombination fragment coupling of unstrained and nondirecting group-Assisted silyl ketones is described. The inexpensive and readily available catalyst performs
Srimontree, Watchara,Lakornwong, Waranya,Rueping, Magnus
supporting information
p. 9330 - 9333
(2019/11/19)

Preparing method of 2-substituted-1,3-dithiane derivative
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; 0033-0035

(2018/10/02)

Visible-light promoted dithioacetalization of aldehydes with thiols under aerobic and photocatalyst-free conditions
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
supporting information
p. 5117 - 5122
(2018/11/24)

Sulfur-Directed Ligand-Free C-H Borylation by Iridium Catalysis
An iridium-catalyzed ortho C-H borylation reaction directed by cyclic dithioacetal moiety is disclosed. A series of borylation products were obtained in moderate to good yields under mild conditions in exclusive mono- and ortho-regioselectivity. Thus, the 1,3-dithiane or 1,3-dithiolane group serves as a remarkable effective directing group for C-H borylation without any ligand assistance. The further transformations of the borylation products are also carried out to change boryl group to other functional groups.
Liu, Li,Wang, Guanghui,Jiao, Jiao,Li, Pengfei
supporting information
p. 6132 - 6135
(2017/11/24)

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
p. 112 - 118
(2017/01/18)

Oxidative [1,2]-Brook Rearrangements Exploiting Single-Electron Transfer: Photoredox-Catalyzed Alkylations and Arylations
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.
supporting information
p. 9487 - 9490
(2017/07/24)

Thioacetalization of aldehydes and ketones catalyzed by hexabromoacetone
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
supporting information
p. 1034 - 1039
(2017/09/08)

Rhodium(III)-catalyzed oxidative alkenylation of 1,3-dithiane-protected arenecarbaldehydes via regioselective C-H bond cleavage
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
supporting information
p. 704 - 707
(2015/03/05)

Sulfonated polyanthracene-catalyzed highly efficient and chemoselective thioacetalization of carbonyl compounds and transthioacetalization of acetals and acylals
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
p. 16 - 29
(2015/10/20)

DENTAL MATERIALS BASED ON MONOMERS HAVING DEBONDING-ON-DEMAND PROPERTIES
The invention relates to a dental restorative material which comprises a thermolabile or photolabile polymerizable compound of Formula I: [(Z1)m-Q1-X)]k-T-[Y-Q2-(Z2)n]1??Formula I, in which T represents a thermolabile or photolabile group, Z1 and Z2 in each case independently represent a polymerizable group selected from vinyl groups, CH2═CR1—CO—O— and CH2═CR1—CO—NR2— or an adhesive group selected from —Si(OR)3, —COOH, —O—PO(OH)2, —PO(OH)2, —SO2OH and —SH, wherein at least one Z1 or Z2 is a polymerizable group, Q1 in each case independently is missing or represents an (m+1)-valent linear or branched aliphatic C1-C20 radical which can be interrupted by —O—, —S—, —CO—O—, —O—CO—, —CO—NR3—, —NR3—CO—, —O—CO—NR3—, —NR3—CO—O— or —NR3—CO—NR3—, Q2 in each case independently is missing or represents an (n+1)-valent linear or branched aliphatic C1-C20 radical which can be interrupted by —O—, —S—, —CO—O—, —O—CO—, —CO—NR3—, —NR3—CO—, —O—CO—NR3—, —NR3—CO—O— or —NR3—CO—NR3—, X and Y in each case independently are missing or represent —O—, —S—, CO—O—, —O—CO—, —CO—NR3—, —NR3—CO—, —O—CO—NR3—, —NR3—CO—O— or —NR3—CO—NR3—, R, R1, R2 and R3 in each case independently represent H or a C1-C7 alkyl radical and k, l, m and n in each case independently are 1, 2 or 3.
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Paragraph 0242; 0243; 0244; 0245

(2014/11/13)

Synthesis of chiral α-diarylacetic esters by stereospecific 1,2-aryl migration promoted by in situ generated acetals from benzoins
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
supporting information
p. 1278 - 1281
(2014/04/03)

Fe-catalyzed direct dithioacetalization of aldehydes with 2-chloro-1,3-dithiane
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
supporting information
p. 4396 - 4399
(2015/01/08)

Facile deprotection of dithioacetals by using a novel 1,4-benzoquinone/cat. NaI system
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
p. 9192 - 9199
(2013/10/01)

Chemoselective and odorless transthioacetalization of acetals using α-oxo-ketene dithioacetals as thiol equivalents
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
p. 1280 - 1286
(2013/04/10)

Silica phenyl sulfonic acid as a solid acid heterogeneous catalyst for chemoselective thioacetalization of carbonyl compounds and dethioacetalization under mild conditions
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
p. E204-E206
(2013/06/04)

Aluminum hydrogen sulfate [Al(HSO4)3] as an efficient catalyst for the preparation of thioacetals
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
p. 2837 - 2842
(2013/07/26)

SBA-15 functionalized sulfonic acid containing a confined hydrophobic and acidic ionic liquid: A highly efficient catalyst for solvent-free thioacetalization of carbonyl compounds at room temperature
A novel application of SBA-15 functionalized sulfonic acid containing a confined ionic liquid has been introduced to convert various carbonyl compounds to their corresponding dithioacetals and dithioketals at room temperature and under solvent-free condit
Karimi, Babak,Vafaeezadeh, Majid
p. 23207 - 23211
(2013/11/19)

Synthetic strategy toward γ-KETO NITRILES and their Biocatalytic conversion to asymmetric γ-lactones
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.
p. 2171 - 2178
(2013/08/23)

Palladium-catalyzed fluoride-free cross-coupling of intramolecularly activated alkenylsilanes and alkenylgermanes: Synthesis of tamoxifen as a synthetic application
We have demonstrated that intramolecular hypercoordination of a carboxylic acid is a powerful activation strategy for the palladium-catalyzed cross-coupling reaction of trialkyl(vinyl)silanes and trialkyl(vinyl)germanes under fluoride-free conditions. Z-β-Trialkylsilyl- and Z-β- trialkylgermylacrylic acids, synthesized stereoselectively by olefination with ynolates, are highly stable and useful reagents for cross-coupling with a variety of aryl iodides to provide tetrasubstituted olefins possessing different carbon substituents in a stereocontrolled and diversity-oriented manner. An application to a stereoselective synthesis of (Z)-tamoxifen is also reported. Copyright
Matsumoto, Kenji,Shindo, Mitsuru
supporting information; experimental part
p. 642 - 650
(2012/05/04)

Preyssler-type heteropoly acid: A new, mild and efficient catalyst for protection of carbonyl compounds
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
experimental part
p. 435 - 438
(2012/01/03)

Silica-supported phosphorus pentoxide: A reusable catalyst for S,S-acetalization of carbonyl groups under ambient conditions
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
experimental part
p. 85 - 91
(2012/01/06)

Dithioacetalization of carbonyl compounds under catalyst-free condition
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
scheme or table
p. 575 - 581
(2012/04/23)

New synthetic strategy for high-enantiopurity N-protected α-amino ketones and their derivatives by asymmetric hydrogenation
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
supporting information; experimental part
p. 253 - 256
(2011/04/16)

Synthesis and deprotection of 1,3-Dithianes and 1,3-Dithiolanes by polyphosphoric acid
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
scheme or table
p. 1117 - 1119
(2011/12/16)

Chemoselective (trans)thioacetalization of carbonyl compounds with a reusable lewis acid-surfactant-combined copper bis(dodecyl sulfate) catalyst in water
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
experimental part
p. 1493 - 1499
(2010/10/03)

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)

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)

Synthesis of benzo[b]furans by palladium-NHC catalyzed ring closure of o-bromobenzyl ketones
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
scheme or table
p. 85 - 90
(2009/06/18)

Silica-PCl5: A novel heterogenous catalyst for simple and efficient chemoselective protection of carbonyl compounds
A simple, efficient and environmentally benign procedure has been developed for chemoselective protection of carbonyl compounds using the newly developed heterogeneous catalyst: Silica-PCl5. A variety of aldehydes and ketones were efficiently c
Pandey, Lokesh Kumar,Pathak, Uma,Tank, Rekha,Mazumder, Avik
experimental part
p. 167 - 171
(2010/07/05)

Trichloromelamine (TCM) - Catalyzed efficient and selective thioacetalization of aldehydes and transthioacetalization of acetals and oxathioacetals under mild reaction conditions
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
p. 2597 - 2606
(2008/12/22)

NOVEL 2-AMINO-5, 5-DIARYL-IMIDAZOL-4-ONES
This invention relates to novel compounds having the structural formula (I) below: and to their pharmaceutically acceptable salt, compositions and methods of use. These novel compounds provide a treatment or prophylaxis of cognitive impairment, Alzheimer Disease, neurodegeneration and dementia.
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Page/Page column 158-159

(2008/12/06)

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)

Synthesis and cytotoxic activities of 4,5-diarylisoxazoles
A series of 4,5-diarylisoxazoles related to combretastatin A-4 (CA-4) were synthesized and evaluated for cytotoxicity against three human cancer cell lines. Among them, compound 6e showed better cytotoxic activity than CA-4 in HeLa and HepG2 cell lines as
Sun, Chang-Ming,Lin, Lee-Gin,Yu, Hsi-Jung,Cheng, Chih-Yu,Tsai, Ya-Chuan,Chu, Chi-Wei,Din, Yi-Hui,Chau, Yat-Pang,Don, Ming-Jaw
p. 1078 - 1081
(2007/10/03)

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
p. 3801 - 3804
(2008/02/09)

Chemoselective dithioacetalization of aldehydes using silica sulfuric acid as a reusable catalyst
Silica sulfuric acid has been found to be an efficient and reusable catalyst for chemoselective dithioacetalization of aldehydes over ketones, in excellent yields.
Pore,Desai, Uday V.,Mane,Wadgaonkar
p. 1291 - 1295
(2007/10/03)

Perchloric acid adsorbed on silica gel (HClO4-SiO2) as an extremely efficient and reusable catalyst for 1,3-dithiolane/dithiane formation
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.
p. 2767 - 2771
(2008/02/05)

A mild and chemoselective dithioacetalization of aldehydes in the presence of anhydrous copper (II) sulfate
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
p. 1445 - 1450
(2007/10/03)

Chemoselective thioacetalization with odorless 2-(1,3-dithian-2-ylidene)-3- oxobutanoic acid as a 1,3-propanedithiol equivalent
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
p. 1741 - 1745
(2007/10/03)

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
p. 4535 - 4537
(2007/10/03)