- Diol-Ritter Reaction: Regio- And Stereoselective Synthesis of Protected Vicinal Aminoalcohols and Mechanistic Aspects of Diol Monoester Disproportionation
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The well-known epoxide-Ritter reaction generally affords oxazolines with poor to average regioselectivity. Herein, a mechanism-based study of the less known diol-Ritter reaction has provided a highly regioselective procedure for the synthesis of 1-vic-amido-2-esters from either terminal epoxides or 1,2-diols via Lewis acid-catalyzed monoesterification. When treated with a stoichiometric Lewis acid catalyst (BF3), these diol monoesters form dioxonium cation intermediates that are ring-opened with nitrile nucleophiles to form nitrilium intermediates, which undergo rapid and irreversible hydration to give the desired amidoesters. Diester byproduct formation is irreversible and appears to occur through disproportionation of diol monoester. With chiral epoxide starting materials, the formation of amidoester occurs with retention of configuration and no apparent erosion of optical purity as determined by single-crystal X-ray analyses and chiral chromatography, respectively. The direct access to chiral vic-amidoesters is especially practical with regard to the synthesis of antibacterial oxazolidinone analogues of the Zyvox antimicrobial family.
- Abboud, Khalil A.,Cheng, Kevin,Klosin, Jerzy,Kruper, William J.,Kruper, William R.,Lysenko, Ivan,Ondari, Mark E.,Thomas, Pulikkottil J.
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- Efficient and regioselective ring-opening of epoxides with carboxylic acid catalyzed by graphite oxide
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An efficient, simple and regioselective ring-opening reaction of epoxides with various carboxylic acids under metal-free conditions is reported. The ring-opening of epoxides takes place in the presence of graphite oxide as an efficient and available catalyst to produce the corresponding 2-hydroxy monoester and 1,2-diester derivatives in good yields. Regioselective attack of the nucleo-phile, short reaction times, metal-free conditions and reusability of catalyst are among the advantages of the present protocol.
- Mirza-Aghayan, Maryam,Tavana, Mahdieh Molaee,Niazi, Elaheh Golam Alipour,Boukherroub, Rabah
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p. 532 - 538
(2020/07/17)
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- Heterogeneous acidic and eco-friendly reagents for mild and convenient conversion of epoxides to 1,2-diacetates
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A highly regioselective ring-opening of epoxides with acetic anhydride in the presence of hydrated disodium hydrogen phosphate and sodium hydrogen sulfate as efficient and eco-friendly reagents is described. The reactions are clean and lead to 1,2-diacetates in high to excellent yields.
- Gilanizadeh, Masumeh,Zeynizadeh, Behzad
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p. 296 - 298
(2016/07/06)
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- A highly efficient protocol for regioselective ring-opening of epoxides with alcohols, water, acetic acid, and acetic anhydride catalyzed by SbF3
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SbF3as an efficient catalyst has been used for regioselective alcoholysis, acetolysis and hydrolysis of epoxides to the corresponding β-alkoxy, β-acetoxy alcohols, and 1,2-diols in high to excellent yields. This study also represents a convenient synthesis of vic-diacetates from ring-opening of epoxides with acetic anhydride.
- Zeynizadeh, Behzad,Gilanizadeh, Masumeh,Aminzadeh, Farkhondeh Mohammad
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p. 1051 - 1056
(2016/07/06)
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- Direct transformation of epoxides to 1,2-diacetates with Ac2O/B(OH)3 system
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Direct transformation of different kinds of epoxides to 1,2-diacetates was carried out easily and efficiently with Ac2O/B(OH)3 system. All reactions were carried out under reflux conditions within 2 h to afford 1,2-diacetates in high yields.
- Gilanizadeh, Masumeh,Zeynizadeh, Behzad
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p. 1234 - 1238
(2016/01/12)
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- Aerobic palladium-catalyzed dioxygenation of alkenes enabled by catalytic nitrite
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Catalytic nitrite was found to enable carbon-oxygen bond-forming reductive elimination from unstable alkyl palladium intermediates, providing dioxygenated products from alkenes. Avariety of functional groups were tolerated, and high yields (up to 94%) were observed with many substrates, also for a multigram-scale reaction. Nitrogen dioxide, which could form from nitrite under the reaction conditions, was demonstrated to be a potential intermediate in the catalytic cycle. Furthermore, the reductive elimination event was probed with 18O-labeling experiments, which demonstrated that both oxygen atoms in the difunctionalized products were derived from one molecule of acetic acid.
- Wickens, Zachary K.,Guzmn, Pablo E.,Grubbs, Robert H.
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supporting information
p. 236 - 240
(2015/02/05)
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- A biocatalytic approach for regioselective monoacetylation of 3-aryloxy-1,2-propanediols by porcine pancreatic lipase
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Among the various lipases screened for the regioselective monoacetylation of 3-aryloxy-1,2-propanediols, porcine pancreatic lipase was found to afford a higher yield. The selectivity for the monoacetylation process was maximized by using different organic solvents and diisopropyl ether gave the highest conversion to monoacetylated product (ca. 98%). The optimized reaction afforded excellent yields of the monoacetylated product with regioselectivity at the terminal hydroxyl group in the presence of various aryl substituents in the starting material. Springer-Verlag 2011.
- Meena, Vachan Singh,Banerjee
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scheme or table
p. 951 - 953
(2012/08/29)
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- One-pot catalytic conversion of epoxides to 1,2-diacetates with hydride transferring agents in acetic anhydride
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Direct transformation of structurally different epoxides to the corresponding 1,2-diacetates was studied with catalytic amounts of NaBH 4, LiAlH4, CaH2, and NaH. The reactions were carried out in refluxing acetic anhydride within 1.5-2.5h to give vic-diacetates in good to excellent yields. Conversion of R-(+)-styrene oxide to S-(+)-1,2-diacetoxy-1-phenylethane was carried out with good yield and stereospecificity with the NaBH4/Ac2O system at 0°C.
- Zeynizadeh, Behzad,Sadighnia, Leila
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experimental part
p. 637 - 644
(2011/03/21)
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- Investigation of the catalytic activity of an electron-deficient vanadium(IV) tetraphenylporphyrin: A new, highly efficient and reusable catalyst for ring-opening of epoxides
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In this work, the catalytic activity of high-valent tetraphenylporphyrinatovanadium(IV) trifluoromethanesulfonate, [V IV(TPP)(OTf)2], in the nucleophilic ring-opening of epoxides is reported. This new V(IV) catalyst was used as an efficient catalyst for alcoholysis with primary (methanol, ethanol and n-propanol), secondary (iso-propanol) and tertiary alcohols (tert-butanol), hydrolysis and acetolysis of epoxides with acetic acid and also for the conversion of epoxides to 1,2-diacetates with acetic anhydride, conversion of epoxides to thiiranes with ammonium thiocyanate and thiourea, and for conversion of epoxides to acetonides with acetone. The catalyst was reused several times without loss of its activity.
- Taghavi, S. Abdolmanaf,Moghadam, Majid,Mohammadpoor-Baltork, Iraj,Tangestaninejad, Shahram,Mirkhani, Valiollah,Khosropour, Ahmad Reza,Ahmadi, Venus
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experimental part
p. 2244 - 2252
(2011/10/03)
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- A green protocol for catalytic conversion of epoxides to 1,2-diacetoxy esters with phosphomolybdic acid alone or its supported on silica gel
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Catalytic conversion of structurally different epoxides to the corresponding 1,2-diacetoxy esters was carried out readily with phosphomolybdic acid alone or its supported on SiO2. The reactions were carried out under solvolytic or solvent free conditions within 5-15 min at room temperature. The product 1,2-diacetates were obtained in high to excellent yields. Supporting of phosphomolybdic acid on SiO2 showed the better catalytic activity than Al2O3. Conversion of optically pure R-(+)-styrene oxide to S-(+)-1,2-diacetoxy-1-phenylethane was carried with phosphomolybdic acid in high yield and stereospecificity.
- Zeynizadeh, Behzad,Sadighnia, Leila
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experimental part
p. 2644 - 2648
(2010/12/25)
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- Efficient preparation of vic-diacetates from epoxides and acetic anhydride in the presence of iron(III)-substituted polyoxometalate as catalyst
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Iron(III)-substituted polyoxometalate (TBA)4PFeW 11O39· 3H2O, has been demonstrated as an efficient catalyst in the ring opening of 1,2-epoxides with acetic anhydride for the one-pot synthesis of 1,2-diol esters in high to excellent yields under solvent-free condition. Copyright
- Yadollahi, Bahram,Esfahani, Farhad Kabiri
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p. 676 - 677
(2008/02/07)
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- Discriminative Glycosylation of 3-(Aryloxy)propane-1,2-diols by Choice of a Glycosyl Donor
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Regioselective glycosylation of rac-guaifenesin (1A) with various glycosyl donors viz., β-D-glucosepentaacetate (2), pyridyl 2,3,4,6-O-tetra-O-benzyl- 1-thio-β-D-galactopyranoside (9), 1-O-acetyl-2,3,5-tri-O-benzoyl-α/ β-D-ribo- (13) and xylofuranoside (17) is reported. Glycosyl donors 2, 13 and 17 bearing ester protecting groups is reported to exhibit high regioselectivity to form the corresponding diastereomeric mixture of 1-O-glycosylated guaifenesin derivatives 3A, 14A and 18A, respectively; formation of diglycosylated derivatives 5A, 15A and 19A is not observed. While no such selectivity is observed when the donor 9 bearing ether protecting groups is used in the coupling reaction with 1A, resulting in the formation of digalactosylated derivatives 10A. That the regioselectivity is not dependent upon substituents present on the aromatic ring is shown by coupling IB with 2 to isolate 1-O-glycosylated derivative 3B; formation of diglycosylated derivative 5B was not observed. Applicability of this finding is shown by preparation of enantiopure guaifenesin [(R)-1 (98% ee) and (S)-1 (98% ee)] by separation of their corresponding diastereomers (R)-3 and (S)-3, respectively.
- Mereyala, Hari Babu,Mamidyala, Sreeman Kumar,Chigurapati, Krishna Prasad,Srinivasa, Sastri R.
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p. 2378 - 2384
(2007/10/03)
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- Kinetic resolution of acyclic 1,2-diols using a sequential lipase- catalyzed transesterification in organic solvents
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A method for the kinetic resolution of 3-(aryloxy)-1,2-propanediols rac- 1a-n without additional protection-deprotection steps using a lipase- catalyzed sequential transesterification with lipase amano PS has been developed. In the first step of this one-pot procedure the racemic 1,2-diols are acylated regioselectively at the primary hydroxy group without enantioselection. The subsequent acylation at the secondary hydroxy group of the formed primary monoacetate is responsible for high enantioselection. The enantioselectivity of this transformation depends significantly on the substitution pattern of the aryl ring and the organic solvent used. 3- (Aryloxy)-1,2-propanediols with substituents in the para-position show a much higher enantioselectivity than the corresponding derivatives with ortho- substituents. Among other substrates, the pharmaceuticals Mephenesin, Guaifenesin, and Chlorphenesin have been resolved. The replacement of the aryloxy by an alkyl substituent causes a dramatic decrease of enantioselectivity.
- Theil,Weidner,Ballschuh,Kunath,Schick
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p. 388 - 393
(2007/10/02)
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- Kinetic resolution of aliphatic 1,2-diols by a lipase-catalyzed sequential acetylation
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The kinetic resolution of 13 racemic aliphatic 1,2-diols (rac-1a-m) by means of a lipase-catalyzed sequential acetylation was investigated. The enantioselectivity of the 3-aryloxy-propane-1,2-diols rac-1a-k depends on the substitution pattern at the aryl ring.
- Theil, Fritz,Weidner, Judith,Ballschuh, Sibylle,Kunath, Annamarie,Schick, Hans
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p. 305 - 306
(2007/10/02)
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