- Ni-Catalyzed Formal Cross-Electrophile Coupling of Alcohols with Aryl Halides
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Direct coupling of unactivated alcohols remains a challenge in current synthetic chemistry. We herein demonstrate a strategy building upon in situ halogenation/reductive coupling of alcohols with aryl halides to forge Csp2-Csp3 bonds. The combination of 2-chloro-3-ethylbenzo[d]oxazol-3-ium salt (CEBO) and TBAB as the mild bromination reagents enables rapid transformation of a wide range of alcohols to their bromide counterparts within one to 5 min in CH3CN and DMF, which is compatible with the Ni-catalyzed cross-electrophile coupling conditions in the presence of a chemical reductant. The present method is suitable for arylation of a myriad of structurally complex alcohols with no need for prepreparation of alkyl halides. More importantly, the mild and kinetically rapid bromination process has shown good selectivity in the bromination/arylation of symmetric diols and less sterically hindered hydroxyl groups in polyols, thus offering promise for selective functionalization of diols and polyols without laborious protecting/deprotecting operations. The practicality of this work is also evident in the arylation of a number of carbohydrates, drug compounds, and naturally occurring alcohols.
- Lin, Quan,Ma, Guobin,Gong, Hegui
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p. 14102 - 14109
(2021/11/20)
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- Acid-Catalyzed Intramolecular Ring-Opening Reactions of Cyclopropanated Oxabenzonorbornadienes with Carboxylic Acid Nucleophiles
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The present work demonstrates the ability of carboxylic acid tethered cyclopropanated oxabenzonorbornadienes (CPOBDs) to undergo ring-opening reactions in mild acidic conditions. The optimized reaction conditions involve the use of pTsOH in DCE at 90 °C. Two regioisomers are formed but the reactions are highly regioselective towards type 3 ring-opened products. It was observed that substitution at the C5 and aryl positions of CPOBD significantly hinders the ring-opening reactions leading to decreased yields of ring-opened products, although high regioselectivity for the Type 3 ring-opened products is still maintained. Herein, the first examples of acid-catalyzed intramolecular ring-opening reactions of CPOBD with carboxylic acid nucleophiles are reported.
- Carlson, Emily,Ho, Angel,Koh, Samuel,Macleod, Matthew P.,Pounder, Austin,Tam, William
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- Primary Alcohols via Nickel Pentacarboxycyclopentadienyl Diamide Catalyzed Hydrosilylation of Terminal Epoxides
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The efficient and regioselective hydrosilylation of epoxides co-catalyzed by a pentacarboxycyclopentadienyl (PCCP) diamide nickel complex and Lewis acid is reported. This method allows for the reductive opening of terminal, monosubstituted epoxides to form unbranched, primary alcohols. A range of substrates including both terminal and nonterminal epoxides are shown to work, and a mechanistic rationale is provided. This work represents the first use of a PCCP derivative as a ligand for transition-metal catalysis.
- Lambert, Tristan H.,Steiniger, Keri A.
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supporting information
p. 8013 - 8017
(2021/10/25)
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- Method for preparing high-purity Fudosteine
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The invention provides a preparation method of a novel antitussive phlegm-eliminating drug high-purity fudosteine, wherein the preparation method includes the steps: (1) synthesizing an intermediate 3-bromo-1-propanol; (2) carrying out a reaction of cysteine hydrochloride with 3-bromo-1-propanol to obtain a crude product; and (3) carrying out crystallization refining on the obtained crude product to obtain the high-purity fudosteine. The domestic cheap easily-available raw materials of cysteine hydrochloride, hydrobromic acid and 1,3-propylene glycol materials are utilized, monitoring of a gas chromatograph, a liquid chromatograph and a refractometer is used for tracking a catalytic reaction process and a reaction terminal point. The preparation method has the advantages of less reaction steps, high selectivity, low pollution, low cost and stable quality, and is suitable for industrialized production.
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Paragraph 0022; 0023-0024; 0026
(2018/03/01)
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- Preparation of useful building blocks, α-iodo- and bromoalkanols from cyclic ethers using the Dowex H+/NaX (X = I, Br) approach
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Our recently reported novel green chemistry tool was effectively used for opening cyclic ethers to produce α-iodo- and bromoalkanols. The synthesis of 4-iodobutanoic acid from γ-butyrolactone has also been described. The method is based on the use of a dried Dowex H+/NaX (X = Br, I)-system, which is effective at producing α-iodoalkanols and some α-bromoalkanols from commercially available cyclic ethers. Additionally, opening of three different crown ethers to form α-iodo(polyethylene)glycols with various chain lengths is demonstrated. Haloalkanols are important building blocks in synthetic chemistry e.g. for medicinal chemistry purposes.
- Turhanen, Petri A.,Veps?l?inen, Jouko J.
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p. 15937 - 15940
(2016/02/19)
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- NOVEL CONJUGATES, PREPARATION THEREOF, AND THERAPEUTIC USE THEREOF
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Provided herein are cryptophycin conjugates and compositions containing them. Methods of making and using such compounds also are provided
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- Simple and efficient method for deprotection of tetrahydropyranyl ethers by using Silica supported sodium hydrogen sulphate
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Tetrahydropyranyl (THP) ethers have been efficiently and simply deprotected by using Silica supported sodium hydrogen sulphate (NaHSO4-SiO 2) in methanol at room temperature to regenerate the parent alcohols in high yields. Tetrahydropyranyl (THP) ethers have been efficiently and simply deprotected by using silica supported sodium hydrogen sulphate (NaHSO 4-SiO2) in methanol at room temperature to regenerate the parent alcohols in high yields.
- Kumar, K. Ravi,Satyanarayana,Reddy, B. Srinivasa
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experimental part
p. 1189 - 1191
(2012/07/27)
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- Oxidation of organotrifluoroborates via oxone
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A method for the oxidation of organotrifluoroborates using Oxone was developed. A variety of aryl-, heteroaryl-, alkenyl-, and alkyltrifluoroborates were converted into the corresponding oxidized products in excellent yields. This method proved to be tolerant of a broad range of functional groups, and in secondary alkyl substrates it was demonstrated to be completely stereospecific.
- Molander, Gary A.,Cavalcanti, Livia N.
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experimental part
p. 623 - 630
(2011/03/20)
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- A concise synthesis of sex pheromone of mediterranean fruit fly, ceratitis capitata via lithiated carbanion derived from enephosphoramide
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A novel and versatile synthetic approach to the preparation of (E)-non-6-en-1-ol, a sex pheromone of the Mediterranean fruit fly, Ceratitis capitata, is presented. This pheromone can be viewed as potential active component for lures designed to control and eradication of Mediterranean fruit fly. The described protocol is a six-step reaction sequence producing the desired compound with 28% overall yield from commercially available and inexpensive starting material and total E stereoselectivity of the double bond present in final structure. The key to the success ofthe presented strategy is application oflithiated α-allylphosphoramido carbanions and their reaction with halogenated acetals.
- Olszewski, Tomasz Krzysztof,Grison, Claude
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experimental part
p. 139 - 147
(2011/06/28)
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- A novel, chemoselective and efficient microwave-assisted deprotection of silyl ethers with Selectfluor
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A novel microwave-assisted, chemoselective and efficient method for the cleavage of silyl ethers (aliphatic and aromatic) catalyzed by Selectfluor is reported. A wide range of TBS-, TIPS-, and TBDPS-protected alkyl silyl ethers can be chemoselectively cleaved in high yield in the presence of aryl silyl ethers. The chemoselective deprotection of phenolic TBS ethers, and not the TIPS- or TBDPS-protected phenolic ethers, and the deprotection of silyl esters were also achieved under these reaction conditions. In addition, the transetherification and etherification of benzylic hydroxy groups in alcoholic solvents is observed.
- Shah, Syed Tasadaque A.,Singh, Surendra,Guiry, Patrick J.
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experimental part
p. 2179 - 2182
(2009/07/01)
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- The chemoselective and efficient deprotection of silyl ethers using trimethylsilyl bromide
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An efficient and chemoselective cleavage of silyl ethers (primary, secondary and aromatic) by using catalytic quantities of trimethylsilyl bromide (TMSBr) in methanol is reported. A wide range of alkyl silyl ethers such as TBS, TIPS, and TBDPS can be chemoselectively cleaved in high yield in the presence of aryl silyl ethers. The deprotection of silyl esters was also achieved employing catalytic quantities of TMSBr. The Royal Society of Chemistry 2008.
- Shah, Syed Tasadaque A.,Guiry, Patrick J.
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experimental part
p. 2168 - 2172
(2009/02/01)
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- 2,3,4,5-TETRAHYDRO-1H-1,5-BENZODIAZEPINE DERIVATIVE AND MEDICINAL COMPOSITION
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The present invention has its object to provide a 2,3,4,5-tetrahydro-1H-1,5-benzodiazepine derivative represented with the Formula (1) , or the pharmaceutically acceptable salt, which is effective as a therapeutic and prophylactic agent for diabetes, diabetic nephropathy, or glomerulosclerosis.
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- Synthesis of hydroxylated hydrocarbons
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Ethylene glycol, other diols, triols, and polyols are made in an efficient manner by reacting dibromides with water in the presence of a metal oxide. An integrated process of dibromide formation, alcohol synthesis, metal oxide regeneration, and bromine recycling is also provided.
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Page/Page column 6
(2008/06/13)
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- Asymmetric synthesis of (-)-α-conhydrine
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The enantioselective synthesis of (-)-α-conhydrine has been achieved by two different synthetic routes. The key steps include Sharpless asymmetric dihydroxylation, regioselective opening of a cyclic sulfate and Wittig olefination.
- Kandula, Subba Rao V.,Kumar, Pradeep
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p. 3268 - 3274
(2007/10/03)
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- Synthesis of the marine compound (2R,5Z,9Z)-2-methoxyhexacosa-5,9-dienoic acid via a lipase-catalyzed resolution and a novel O-alkylation protocol
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The title compound has been synthesized by a facile route starting from 4-pentyn-1-ol. The enantioselectivity was attained by a strategy involving a lipase-catalyzed acetylation of a solid-phase immobilized long chain α-hydroxy acid. Another important feature of the synthesis was the formulation of an efficient HgO-catalyzed O-methylation of the α-hydroxy acids which proceeded without any racemization. The alkylation protocol was also highly efficient for selective mono-methylation/benzylation of symmetrical diols.
- Kulkarni, Bheemashankar A.,Sharma, Anubha,Gamre, Sunita,Chattopadhyay, Subrata
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p. 595 - 599
(2007/10/03)
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- Functional group transformations of diols, cyclic ethers, and lactones using aqueous hydrobromic acid and phase transfer catalyst under microwave irradiation
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Synthesis of bromoalkanols has been achieved from diols, ethers, and lactones using aq HBr (48%) and tetrabutylammonium iodide/bromide as phase transfer catalyst under microwave irradiation. This environmentally benign route provides enhanced yields of products and does away with the use of benzene as compared to existing conventional methods.
- Kad, Goverdhan L.,Kaur, Irvinder,Bhandari, Monica,Singh, Jasvinder,Kaur, Jasamrit
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p. 339 - 340
(2013/09/06)
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- Agarofuan derivatives, their preparation, pharmaceutical composition containing them and their use as medicine
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The compound represented by formula (I), in which the substitutes are defined as in the specification and the claims, or their stereoisomers, the process for preparing them, pharmaceutical composition containing them and their use as medicine.
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- STEREOSPECIFIC SYNTHESIS OF COMPONENTS OF THE NATURAL SEX PHEROMONE OF Pectinophora gossypiella
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A multistage stereospecific synthesis of components of the natural pheromone was realized.Conditions were found for stereospecific trans-reduction of the triple bonds.A procedure was developed for regiospecific dehydrohalogenation of 1,2-dibromoalkanes.Conditions giving the Z and E isomers in ratio of 96 : 4 were found for the Wittig reaction.
- Matveeva, E. D.,Kvasha, M. P.,Kurts, A.L.
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p. 1017 - 1021
(2007/10/02)
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- Improved method for the selective conversion of aliphatic esters to alcohols by zinc borohydride in tetrahydrofuran
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Selective conversion of aliphatic esters to the corresponding alcohols has been achieved in excellent yields by zinc borohydride in tetrahydrofuran under mild conditions (67 deg C, 6 hr).Unsaturated esters produce the corresponding diols.
- Narasimhan, S,Palmer, Prem
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p. 701 - 702
(2007/10/02)
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- Use of Zinc Borohydride for Efficient Reduction of Carboxylic Ester to Alcohol. Selective Reduction of Aliphatic Ester in Presence of Aromatic Ester Under Sonication
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An efficient methodology using zinc borohydride under sonication for the reduction of carboxylic esters to alcohols in presence of N,N-dimethylaniline and selective reduction of an aliphatic ester over an aromatic one without N,N-dimethylaniline is described.
- Ranu, Brindaban C.,Basu, Manas K.
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p. 3243 - 3246
(2007/10/02)
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- Regiocontrolled Opening of Cyclic Ethers Using Dimethylboron Bromide
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The cleavage of various cyclic ethers (3- to 7-membered rings) was achieved under very mild conditions using dimethylboron bromide to afford the corresponding bromo alcohols.In particular, 2-substituted tetrahydrofurans were regioselectively cleaved by a predominantly SN2 - type mechanism favoring the formation of primary vs. secondary bromides.Dimethylboron bromide also cleaved chemoselectively substituted tetrahydrofurans in the presence of functional groups such as acyclic ethers, silyl ethers, esters, amides, ketones,etc.
- Guindon, Yvan,Therien, Michel,Girard, Yves,Yoakim, Christiane
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p. 1680 - 1686
(2007/10/02)
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- An Effective Method for the Preparation of ω-Bromoalkanols from α,ω-Diols
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Pure ω-bromoalkanols 2 (n=2-12), not contaminated by any dibromoalkanes or unreacted diols 1, were prepared in good yields by refluxing a mixture of diols 1, aqueous (48percent) hydrogen bromide, and benzene using a Dean-Stark water separator.
- Kang, Suk-Ku,Kim, Won-Sup,Moon, Byoung-Ho
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p. 1161 - 1162
(2007/10/02)
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- HYDROALUMINATION OF ALLYL ALCOHOLS AND ETHERS BY LITHIUM ALUMINUM HYDRIDE IN THE PRESENCE OF ZIRCONIUM CATALYST
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Allyl alcohols and ethers were readily hydroaluminated by LiAlH4 in the presence of zirconium compounds to give organoaluminum compounds in which the aluminum atom is placed at the terminal position of the substrate.ZrCl4 was the most effective catalyst for hydroalumination of allyl alcohols, whilst Cp2ZrCl2 was more effective than ZrCl4 for allyl ethers.
- Sato, Fumie,Tomuro, Yasuji,Ishikawa, Hiroaki,Sato, Masao
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