- 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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- 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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supporting information
p. 5661 - 5664
(2020/06/09)
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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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- Brook/Elimination/Aldol Reaction (BEAR) Sequence for the Direct Preparation of Fluorinated Aldols from β,β-Difluoro-α-(trimethylsilyl)alcohols
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A methodology allowing the preparation of aldols featuring a fluorinated stereogenic center is reported. The corresponding fluoroenolates are formed in situ from stable β,β-difluoro-α-(trimethylsilyl)alcohols, through a base-mediated process involving a Brook rearrangement followed by a fluoride elimination, and are directly added to aromatic aldehydes. Two different sets of conditions were disclosed. The first one involves the stoichiometric addition of potassium tert-butoxide (t-BuOK) while the second is based on the use of a catalytic amount of an ammonium phenoxide. The latter opens the way for a catalytic and asymmetric version of this Brook/elimination/aldol reaction (BEAR) sequence.
- Decostanzi, Mélanie,Van Der Lee, Arie,Campagne, Jean-Marc,Leclerc, Eric
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supporting information
p. 3091 - 3097
(2015/11/03)
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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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- Enamine-lminium ion nazarov cyclization of α-ketoenones
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[Chemical equaction presented] The mono-triflate salts of some chiral nonracemic 1,2-diamines react with α-ketoenones in a stoichiometric reaction to form products of the Nazarov cyclization in high enantiomeric ratios. The mechanism appears to involve rearrangement of an enamine-iminium ion.
- Bow, William F.,Basak, Ashok K.,Jolit, Anais,Vicic, David A.,Tius, Marcus A.
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supporting information; experimental part
p. 440 - 443
(2010/04/24)
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- Prodrugs of GABA analogs, compositions and uses thereof
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The present invention provides prodrugs of GABA analogs, pharmaceutical compositions of prodrugs of GABA analogs and methods for making prodrugs of GABA analogs. The present invention also provides methods for using prodrugs of GABA analogs and methods for using pharmaceutical compositions of prodrugs of GABA analogs for treating or preventing common diseases and/or disorders.
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Page/Page column 42
(2010/11/24)
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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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- Prodrugs of GABA analogs, compositions and uses thereof
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The present invention provides prodrugs of GABA analogs, pharmaceutical compositions of prodrugs of GABA analogs and methods for making prodrugs of GABA analogs. The present invention also provides methods for using prodrugs of GABA analogs and methods for using pharmaceutical compositions of prodrugs of GABA analogs for treating or preventing common diseases and/or disorders.
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- Methods for synthesis of prodrugs from 1-acyl-alkyl derivatives and compositions thereof
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The present invention provides a method for synthesizing 1-(acyloxy)-alkyl derivatives from 1-acyl-alkyl derivatives, which typically proceeds stereospecifically, in high yield, does not require the use of activated intermediates and/or toxic compounds and is readily amenable to scale-up. The current invention also provides 1-acyl-alkyl derivatives of known drug compounds and methods for synthesizing these 1-acyl-alkyl derivatives.
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- A novel method for the preparation of α,α′ -difluoroesters and acids using BrF3
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Alkyl-, haloalkyl-, and ketoalkyl-2-ethoxycarbonyl-1,3-dithianes were easily made from the appropriate primary or secondary alkyl bromides, 1,3-dithiane, and ethyl chloroformate. They were reacted with BrF3 to form the corresponding α,α-difluor
- Hagooly, Aviv,Sasson, Revital,Rozen, Shlomo
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p. 8287 - 8289
(2007/10/03)
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- Transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones catalysed by natural kaolinitic clay
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Natural kaolinitic clay efficiently catalyses the transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones with ethane-1,2-dithiol and propane-1,3-dithiol to produce the corresponding dithiolanes in high yields.
- Jnaneshwara,Barhate,Sudalai,Deshpande,Wakharkar,Gajare,Shingare,Sukumar
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p. 965 - 968
(2007/10/03)
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- Novel amino acid derivatives possessing renin-inhibitory activities
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An amino acid derivative of the general formula: wherein, R1? is a lower alkyl group and R11 is (wherein R111 is a lower alkyl group and n is an integer of 1 to 5) or a lower alkyl group which may be substituted by hydroxy group or methoxyethoxymethoxy group, or R1? and R11 are combinedly together with the adjacent nitrogen atom; R12 is a hydrogen atom, CnH2n+ 1-O-CO-(n is as defined above) or R13 is a lower alkyl group which may be substituted by substituent(s) selected from HOOC-(H?C)n-O-, R12-NH-(n and R12 are as defined above) and pyridyl group; X is-CH?-,-O-or-NH-and Y is-O-or-NH-; wherein (wherein Z is-O-,-S-,-S(O)-,-S(O)?-,-CH?-,-CH(OH)-,---,-NH-or and a and b are independently an integer of 1 to 4 and the total of a and b is not more than 5) ; R2 is an aralkyl group which may be substituted by lower alkyl group(s); R3 is a hydrogen atom or a lower alkyl group; R? is a lower alkyl group; and A is hydroxy group and B is a hydrogen atom, or A and B are carbonyl group combinedly together with the adjacent carbon atom, a pharmaceutically acceptable acid addition salt or an ester thereof is described. The compounds of the invention possess inhibitory activities against renin and are useful as an antihypertensive agent.
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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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p. 2114 - 2116
(2007/10/02)
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- A RAPID, EFFICIENT AND SELECTIVE CONVERSION OF ALDEHYDES AND ACETALS TO THEIR 1,3-DITHIANE DERIVATIVES WITH 2,2-DIMETHYL-2-SILA-1,3-DITHIANE1
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Aldehydes and acetals are cleanly and rapidly converted to the corresponding dithianes with 2,2-dimethyl-2-sila-1,3-dithiane and stochiometric amounts of boron trifluoride etherate even in the presence of ketones, which do not react competitively with the reagent.
- Soderquist, John A.,Miranda, Edgar I.
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p. 6305 - 6306
(2007/10/02)
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- 1,3-Dithienium- and 1,3-Dithiolenium Salts, V. Determination of the Relative Reactivity of 1,3-Dithian-2-ylium Tetrafluoroborates by Intermolecular Hydride Ion Transfer
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The 1,3-dithienium- and 1,3-dithiolenium tetrafluoroborates 4 (n=3, 2) react in good yields with the (trimethylsiloxy)alkenes 3 available from β-dicarbonyl compounds to give the 2-substituted 1,3-dicarbonyl compounds 5.Owing to the formation of the difluoroboron acid esters 8 as competition products 3 has to be employed in excess, however.Reaction of 4 (n=3) with 1,3,5-cycloheptatriene (10) leads to the 1,3-dithianes 11 and the more stable tropylium tetrafluoroborate (12).The determination of the corresponding rates of reduction allows in a simple manner the ascertainment of the relative reactivities of 4.Whereas the reactivities of the aryl-substituted representatives of 4 show a sufficient correlation corresponding to the Hammett relationship, the variations of the reactivities of the alkyl substituted salts 4 can be explained on the basis of hyperconjugative stabilization.
- Stahl, Ingfried
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p. 4857 - 4868
(2007/10/02)
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