- PROBE FOR DETECTING CARBAPENEM-RESISTANT BACTERIA AND USE THEREOF
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The present disclosure relates to a compound represented by Chemical Formula 1, a probe for detecting antibiotic-resistant bacteria, which includes the compound, a composition containing the compound, a kit including the compound and a method for detectin
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Paragraph 0085; 0167-0169
(2021/09/10)
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- Development of carbapenem-based fluorogenic probes for the clinical screening of carbapenemase-producing bacteria
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This report describes the synthesis of a library of fluorogenic carbapenemase substrates consisting of carbapenem derivatives, fluorescence dyes, and active cleavable linkers and their evaluation for specifically detecting carbapenemase-producing organism
- Kim, Juhyeon,Kim, Yihoon,Abdelazem, Ahmed Z.,Kim, Hak Joong,Choo, Hyunah,Kim, Hoon Seok,Kim, Jung Ok,Park, Yeon-Joon,Min, Sun-Joon
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- Hafnium Triflate as a Highly Potent Catalyst for Regio- and Chemoselective Deprotection of Silyl Ethers
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As a Group IVB transition metal Lewis acid, hafnium triflate [Hf(OTf) 4 ] exhibited exceptionally high potency in desilylations. Since the amounts of Hf(OTf) 4 required for the deprotection of 1°, 2°, 3° alkyl and aryl tert -butyldimethylsilyl (TBS) ethers are significantly different, ranging from 0.05 mol% to 3 mol%, regioselective deprotection of TBS could be easily implemented. Moreover, chemoselective cleavage of different silyl ethers or removal of TBS in the presence of most hydroxyl protecting groups was also accomplished. NMR analyses of silyl products from TBS deprotection indicated that Hf(OTf) 4 -catalyzed desilylation may proceed via different mechanisms, depending on the solvent used.
- Zheng, Xiu-An,Kong, Rui,Huang, Hua-Shan,Wei, Jing-Ying,Chen, Ji-Zong,Gong, Shan-Shan,Sun, Qi
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p. 944 - 953
(2019/02/10)
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- Hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method
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The invention provides a hafnium trifluoromethanesulfonate catalyzed silyl ether protecting group removing method. Various silyl ether protecting groups of nearly 50 kinds of substrates can be efficiently removed in 0.5-16 hours at room temperature by taking 0.02mol%-0.3mol% hafnium trifluoromethanesulfonate as a catalyst, a silyl ether protected hydroxyl compound as a substrate and conventional AR methanol as a solvent. 42 kinds of silyl ether protecting group removing products can be obtained at high yield by performing conventional slica column chromatography purification on a crude product. By regulating the use amount of the catalyst, the Hf(OTf)4 catalyst can realize regioselective removal of 1-degree, 2-degree and 3-degree alkyl TBS and aryl TBS protective groups. Moreover, in a proper equivalent scope, the Hf(OTf)4 catalyst can also realize 1) chemoselective removal of different kinds of silica-based protective groups; and 2) chemoselective removal of 1-degree TBS protective groups under the condition of not affecting a majority of common hydroxyl protective groups.
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Paragraph 0011; 0014
(2019/01/21)
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- PRODRUGS OF FUSED-BICYCLIC C5aR ANTAGONISTS
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The present disclosure provides, inter alia, Compounds of Formulae IA, IB, IC, IIA, IIB and IIC or pharmaceutically acceptable salts thereof that are modulators of the C5a receptor. Also provided are pharmaceutical compositions and methods of use including the treatment of diseases or disorders involving pathologic activation from C5a and non-pharmaceutical applications.
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- Highly sulphated cellulose: a versatile, reusable and selective desilylating agent for deprotection of alcoholic TBDMS ethers
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A mild, efficient and rapid protocol was developed for the deprotection of alcoholic TBDMS ethers using a recyclable, eco-friendly highly sulphated cellulose sulphate acid catalyst in methanol. This acid catalyst selectively cleaves alcoholic TBDMS ethers in bis-TBDMS ethers containing both alcoholic and phenolic TBDMS ether moieties.
- Dachavaram, Soma Shekar,Penthala, Narsimha R.,Calahan, Julie L.,Munson, Eric J.,Crooks, Peter A.
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p. 6057 - 6062
(2018/09/06)
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- Diverse ring opening of thietanes and other cyclic sulfides: An electrophilic aryne activation approach
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Organosulfides are a common class of structure units in bioactive molecules and functional materials motivating continuous developments of efficient synthetic methods. Herein, we report an electrophilic aryne-activated ring opening protocol of one or two
- Zheng, Tianyu,Tan, Jiajing,Fan, Rong,Su, Shuaisong,Liu, Binbin,Tan, Chen,Xu, Kun
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supporting information
p. 1303 - 1306
(2018/02/14)
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- Gold-Catalyzed Oxidative Coupling of Alkynes toward the Synthesis of Cyclic Conjugated Diynes
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Gold-catalyzed oxidative coupling of alkynes was developed as an efficient approach for the synthesis of challenging cyclic conjugated diynes (CCD). Compared with the classic copper-promoted oxidative coupling reaction of alkynes, this gold-catalyzed process exhibited a faster reaction rate due to rapid reductive elimination from the Au(III) intermediate. This unique reactivity thus allowed a challenging diyne macrocyclization to take place with high efficiency. Condition screening revealed an [(n-Bu)4N]+[Cl-Au-Cl]? salt as the optimal pre-catalyst. Macrocycles with ring size between 13 and 28 atoms were prepared in moderate to good yields, which highlighted the broad substrate scope of this new strategy. Furthermore, the synthetic utilities of the CCDs for copper-free click chemistry have been demonstrated, showcasing the potential application of this strategy in biological systems. Macrocycles are important structural moieties in medicinal and biological research, and efficient methods for macrocyclization are always in high demand. With the unique conformation having six carbon atoms in a linear geometry, the cyclic conjugated diynes (CCD) present greater synthetic challenges and have been much less explored. Therefore, application of these unique macrocycles in biological studies is largely unexplored. Here, we describe the discovery of gold-catalyzed Glaser-Hay type oxidative coupling of terminal alkynes to achieve CCD under diluted conditions with broad substrate scope and great functional group compatibility. Taking advantage of the 14-member cyclic diyne, a copper-free click chemistry was achieved, which provided an effective alternative strategy for the traditional cyclooctyne-based azide-alkyne cycloaddition, suggesting a promising future for this method in tackling challenging problems in related biological and medicinal research. Gold-catalyzed oxidative coupling of alkynes was developed as an efficient approach for the synthesis of challenging cyclic conjugated diyne. Compared with copper-promoted oxidative coupling, this protocol allowed macrocyclization under dilute conditions with good overall reactivity and high functional group tolerance. The success in achieving copper-free click chemistry on cyclic conjugated diyne highlights its potential application in biological and medicinal research.
- Ye, Xiaohan,Peng, Haihui,Wei, Chiyu,Yuan, Teng,Wojtas, Lukasz,Shi, Xiaodong
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p. 1983 - 1993
(2018/10/02)
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- Michael additions of highly basic enolates to ortho -quinone methides
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A protocol by which ketone or ester enolates and ortho-quinone methides (o-QMs) are generated in situ in a single reaction flask from silylated precursors under the action of anhydrous fluoride is reported. The reaction partners are joined to give a variety of β-(2-hydroxyphenyl)-carbonyl compounds in 32-94% yield in a single laboratory operation. The intermediacy of o-QMs is supported by control experiments utilizing enolate precursors and conventional alkyl halides as competitive alkylating agents and the isolation of 1,5-dicarbonyl products resulting from conjugate additions that do not restore the aromatic system.
- Lewis, Robert S.,Garza, Christopher J.,Dang, Ann T.,Pedro, Te Kie A.,Chain, William J.
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p. 2278 - 2281
(2015/05/13)
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- Enantioselective copper-catalyzed intramolecular phenolic O-H bond insertion: Synthesis of chiral 2-carboxy dihydrobenzofurans, dihydrobenzopyrans, and tetrahydrobenzooxepines
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Efficient: A copper-catalyzed enantioselective intramolecular insertion of carbenoids into phenolic O-H bonds has been developed. This method can be used for the synthesis of the title compounds in high yields and excellent enantioselectivities under mild and neutral conditions (see scheme). NaBAr F=sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate. Copyright
- Song, Xiao-Guang,Zhu, Shou-Fei,Xie, Xiu-Lan,Zhou, Qi-Lin
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p. 2555 - 2558
(2013/04/10)
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- Multidentate triphenolsilane-based alkyne metathesis catalysts
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A series of triphenolsilane-coordinated molybdenum(VI) propylidyne catalysts has been developed, which are resistant to small alkyne polymerization and compatible with various functional groups (including phenol substrates). The catalysts remain active in
- Yang, Haishen,Liu, Zhenning,Zhang, Wei
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p. 885 - 890
(2013/05/08)
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- Highly Active Multidentate Catalysts for Efficient Alkyne Metathesis
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The invention relates to highly active and selective catalysts for alkyne metathesis. In one aspect, the invention includes a multidentate organic ligand wherein one substrate-binding site of the metal center is blocked. In another aspect, the invention includes N-quaternized or silane-based multidentate organic ligands, capable of binding to metals. In yet another aspect, the invention includes N-quaternized or silane-based multidentate catalysts. The catalysts of the invention show high robustness, strong resistance to small alkyne polymerization and significantly enhanced catalytic activity compared to their corresponding non-quaternized or non-silane-based multidentate catalyst analogues.
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- A mild, efficient, and selective deprotection of tert-butyldimethylsilyl (TBDMS) ethers using dicationic ionic liquid as a catalyst
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Selective deprotection of alkyl TBDMS ether in the presence of phenolic TBDMS ether using dicationic ionic liquid [tetraEG(mim)2][OMs] 2 as a homogeneous catalyst showed significant catalytic activity in methanol at ambient temperature to produce respective alcohol in excellent yield. The present environmentally benign catalytic system is found to be very convenient, fast, high yielding, and clean method for selective desilylation of alkyl silyl ethers even in the existence of other sensitive organic functional groups such as aldehyde, methoxy, and acetate were also achieved.
- Jadhav, Arvind H.,Kim, Hern
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p. 5338 - 5342
(2012/11/07)
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- Mild and rapid method for the generation of ortho -(naphtho)quinone methide intermediates
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A new mild method has been devised for generating o-(naphtho)quinone methides via fluoride-induced desilylation of silyl derivatives of o-hydroxybenzyl(or 1-naphthylmethyl) nitrate. The reactive o-(naphtho)quinone methide intermediates were trapped by C,
- Shaikh, Abdul Kadar,Cobb, Alexander J. A.,Varvounis, George
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p. 584 - 587
(2012/03/10)
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- A mild and chemoselective method for the deprotection of tert-butyldimethylsilyl (TBDMS) ethers using iron(III) tosylate as a catalyst
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The most common method for the deprotection of TBDMS ethers utilizes stoichiometric amounts of tetrabutylammonium fluoride, n-Bu4N+F- (TBAF), which is highly corrosive and toxic. We have developed a mild and chemoselective method for the deprotection of TBDMS, TES, and TIPS ethers using iron(III) tosylate as a catalyst. Phenolic TBDMS ethers, TBDPS ethers and the BOC group are not affected under these conditions. Iron(III) tosylate is an inexpensive, commercially available, and non-corrosive reagent.
- Bothwell, Jason M.,Angeles, Veronica V.,Carolan, James P.,Olson, Margaret E.,Mohan, Ram S.
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supporting information; experimental part
p. 1056 - 1058
(2010/04/05)
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- A mild and efficient cleavage of tert-butyldimethylsilyl (TBS) and tetrahydropyranyl (THP) ethers using a catalytic amount of TBPA+ {radical dot} Sb Cl6-
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A mild and efficient method for the deprotection of the TBS and THP ethers is described. A wide variety of TBS ethers as well as THP ethers can be easily deprotected to the corresponding parent hydroxyl compounds by employing a catalytic amount of tris(4-bromophenyl)aminium hexachloroantimonate (TBPA+ {radical dot} Sb Cl6-) in methanol at room temperature in good yield.
- Xu, Yanfen,Tang, Shouchu,Han, Junjie,She, Xuegong,Pan, Xinfu
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p. 3634 - 3637
(2008/09/19)
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- Chemoselective TBS deprotection of primary alcohols by means of pyridinium tribromide (Py·Br3) in MeOH
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A catalytic amount of pyridinium tribromide (Py·Br3) in MeOH chemoselectively deprotects primary TBS ethers in the presence of a variety of other protecting and common functional groups in modest to excellent yields when performed at 0 °C.
- Martinez-Solorio, Dionicio,Jennings, Michael P.
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p. 5175 - 5178
(2008/12/20)
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- Mild and rapid method for the generation of o-quinone methide intermediates. Synthesis of puupehedione analogues
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A route to simpler analogues to bioactive puupehedione derivatives involving a hetero Diels-Alder cycloaddition of a o-quinone methide is described. These intermediate species are generated via fluoride-induced desilylation of silyl derivatives of o-hydro
- Barrero, Alejandro F.,Quílez del Moral, José F.,Mar Herrador,Arteaga, Pilar,Cortés, Manuel,Benites, Julio,Rosellón, Antonio
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p. 6012 - 6017
(2007/10/03)
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- A facile, catalytic, and environmentally benign method for selective deprotection of teri-butyldimethylsilyl ether mediated by phosphomolybdic acid supported on silica gel
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An environmentally benign PMA supported on SiO2 is found to be an efficient catalyst for the chemoselective deprotection of TBDMS ethers under very mild conditions. Various labile functional groups such as isopropylidene acetal, OTBDPS, OTHP, Oallyl, OBn, alkene, alkyne, OAc, OBz, N-Boc, N-Cbz, N-Fmoc, mesylate, and azide are found to be stable under the reaction conditions. This "truly catalytic" heterogeneous reaction does not require aqueous workup, and the supported catalyst and the solvent can be readily recovered and recycled.
- Kishore Kumar,Baskaran, Sundarababu
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p. 4520 - 4523
(2007/10/03)
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- A simple and useful synthetic protocol for selective deprotection of tert-butyldimethylsilyl (TBS) ethers
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A wide variety of tert-butyldimethylsilyl ethers 1 can be easily cleaved to the corresponding parent hydroxyl compound 2 in the presence of 5 mol % of acetonyltriphenylphosphonium bromide (ATPB) at room temperature. In addition, tert-butyldiphenylsilyl ethers can also be cleaved by using 20 mol % of the same catalyst. Alkyl tert-butyldimethylsilyl ethers can be deprotected to the hydroxyl compounds chemoselectively in the presence of aryl tert- butyldimethylsilyl ethers. Some of the major advantages are mild reaction conditions, no aqueous workup, high efficiency and chemoselectivity and compatibility with other protecting groups; no brominations occur in the aromatic ring under these experimental conditions. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Khan, Abu T.,Ghosh, Subrata,Choudhury, Lokman H.
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p. 2198 - 2204
(2007/10/03)
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- A catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol is a good combination for the cleavage of tetrahydropyranyl (THP) and tert-butyldimethylsilyl (TBS) ethers
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Various THP and TBS ethers can be unmasked easily to the corresponding hydroxyl compounds in good yields by using a combination of a catalytic amount of nickel(II) chloride hexahydrate and 1,2-ethanedithiol at room temperature. In addition, alkyl TBS ethers can be hydrolyzed chemoselectively in the presence of aryl TBS ethers. Moreover, alkyl TBS ethers can be cleaved easily in the presence of alkyl or aryl THP ethers using the same conditions.
- Khan, Abu T.,Islam, Samimul,Choudhury, Lokman H.,Ghosh, Subrata
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p. 9617 - 9621
(2007/10/03)
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- Selective deprotection of either alkyl or aryl silyl ethers from aryl, alkyl bis-silyl ethers
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A pair of complementary methods was developed using CeCl3·7H2O/CH3CN and LiOH/DMF to selectively deprotect alkyl and aryl silyl ethers, respectively, from the corresponding bis-silyl ethers in excellent yields.
- Ankala, Sudha V.,Fenteany, Gabriel
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p. 4729 - 4732
(2007/10/03)
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- Ceric ammonium nitrate on silica gel for efficient and selective removal of trityl and silyl groups
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Silicna gel-supported ceric ammonium nitrate (CAN-SiO2) was found effective for rapid and selective cleavage of trityl (Tr), monomethoxytrityl (MMTr), and dimethoxytrityl (DMTr) groups from protected nucleosides and nucleotides under mild conditions. Efficiency of deprotections depended upon the stability of th resultant carbocationic species: DMTr+ > MMTr+ > Tr+. Use of a catalytic amount of this solid-supported reagent can also efficiently and selectively remove the tert butyldimethylsilyl or the triisopropylsilyl group from a primary hydroxyl functionality in di- or trisilyl ethers of ribonucleosides. A comparative stud of deprotection reactions by utilization of CAN alone or CAN-SiO2 indicates a remarkable increase in the rate of the reactions involving a solid support. The mechanism of electron-transfer processes is proposed for the use of CAN-SiO2 in the removal of these protective groups from organic molecules.
- Hwu, Jih Ru,Jain, Moti L.,Tsai, Fu-Yuan,Tsay, Shwu-Chen,Balakumar, Arumugham,Hakimelahi, Gholam H.
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p. 5077 - 5088
(2007/10/03)
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- A novel, highly efficient and selective desilylating method for trialkylsilyl ethers
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A series of tert-butyldimethylsilyl, tert-butyldiphenylsilyl and triisopropylsilyl ethers are hydrolyzed to theirs corresponding alcohols in CBr4 / CH3OH (0.1 eq. / 10mL) reaction system under refluxing condition. The chemoselectivity can be achieved between primary and secondary triisopropylsilyl ethers when more hindered 2-propanol is used instead of methanol.
- Lee, Adam Shih-Yuan,Yeh, Hsiu-Chih,Shie, Jiun-Jie
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p. 5249 - 5252
(2007/10/03)
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- A simple and Highly Chemoselective Desilylation of tert-Butyldimethylsilyl Ethers
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The use of a 0.25M CH3OH/CCl4 (1:1) solvent mixture under ultrasound for the selective deprotection of tert-butyldimethylsilyl ethers of benzyl alcohols is described.This method enables to deprotect tert-butyldimethylsilyl ethers of primary alcohols, whereas tert-butyldimethylsilyl ethers of secondery and tertiary alcohols were stable under the reaction condition.
- Lee, Adam Shih-Yuan,Yeh, Hsiu-Chih,Tsai, Ming-Hung
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p. 6891 - 6894
(2007/10/02)
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- An Efficient and Highly Chemoselective Method to Desilylate Silyl Ethers
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An efficient and highly chemoselective desilylating method is described.Trimethylsilyl ethers (0.25 M) in a CH3OH/CCl4 (1:1) solvent mixture are deprotected to their corresponding alcohols with ultrasound in a commercial ultrasonic cleaning bath.Selective deprotection of tert-butyldimethylsilyl ethers of benzyl alcohols and phenols is achieved under ultrasonic conditions.We deprotected also tert-butyldimethylsilyl ethers of primary alcohols, whereas tert-butyldimethylsilyl ethers of secondary and tertiary alcohols are stable under these conditions. - Key words: Sonochemistry; Ultrasound; Cavitation; Desilylation; Chemoselection; Deprotection.
- Lee, Adam Shih-Yuan,Yeh, Hsiu-Chih,Yeh, Ming-Kuo,Tsai, Ming-Hung
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p. 919 - 922
(2007/10/03)
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- Selective removal of phenolic and alcoholic silyl ethers
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Potassium carbonate/Kriptofix 222 and pyridinium p-toluenesulfonate or BF3-etherate have been found to remove the tert-butyldimethylsilyl group from phenolic and alcoholic silyl ethers, respectively. This methodology should find wide applicability in complex organic synthesis.
- Prakash, Chandra,Saleh, Samir,Blair, Lan A.
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p. 7565 - 7568
(2007/10/02)
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- RHODIUM CARBENOID MEDIATED CYCLISATIONS. PART 2. SYNTHESIS OF CYCLIC ETHERS
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Alkylation of the dianion of methyl acetoacetate with the t-butyldimethylsilyl protected α,ω-halogeno alcohols (1)-(9) gives the β-keto esters (1) which are converted into the diazo alcohols (3) by diazo transfer and desilylation.Rhodium carbenoid cyclisa
- Heslin, Julie C.,Moody, Christopher J.
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p. 1417 - 1424
(2007/10/02)
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- SELECTIVE DEPROTECTION OF ALCOHOLIC AND PHENOLIC SILYL ETHERS
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Hydrofluoric acid and tetrabutylammonium fluoride will selectively deprotect alcoholic and phenolic silyl ethers respectively.
- Collington, Eric W.,Finch, Harry,Smith, Ian J.
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p. 681 - 684
(2007/10/02)
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