- Silica gel-supported bis-cinchona alkaloid: A chiral catalyst for the heterogeneous asymmetric desymmetrization of meso-cyclic anhydrides
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A one-pot conversion of meso-cyclic anhydrides with alcoholysis in diethyl ether using SGS-(DHQ)2AQN 4, a silica gel-supported chiral catalyst, into the corresponding desymmetrized mono ester acids was achieved with enantiomeric excesses of up
- Song, Yu-Mi,Choi, Jin Seok,Yang, Jung Woon,Han, Hogyu
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- Toward aplyronine payloads for antibody-drug conjugates: Total synthesis of aplyronines A and D
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The aplyronines are a family of antimitotic marine macrolides that disrupt cytoskeletal dynamics by dual targeting of both actin and tubulin. Given their picomolar cytotoxicity profile and unprecedented mode of action, the aplyronines represent an excellent candidate as a novel payload for the development of next-generation antibody-drug conjugates (ADCs) for cancer chemotherapy. Enabled by an improved second-generation synthesis of the macrolactone core 5, we have achieved the first total synthesis of the most potent congener aplyronine D together with a highly stereocontrolled synthesis of aplyronine A. To facilitate step economy, an adventurous site-selective esterification of the C7 hydroxyl group was performed to install the N,N,O-trimethylserine pharmacophore to directly afford aplyronines A and D. Toward the assembly of ADCs incorporating an aplyronine warhead, the C29-ester derivative 4 featuring an Fmoc-amino substituted linker attached to the actin-binding tail region was also prepared by adapting this flexible endgame.
- An?i?ek, Nika,Williams, Simon,Housden, Michael P.,Paterson, Ian
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supporting information
p. 1343 - 1350
(2018/03/06)
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- Preparation method of high-purity and high-yield monomethyl 3-methylglutarate
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The invention relates to a preparation method of high-purity and high-yield monomethyl 3-methylglutarate, and belongs to the field of organic synthesis. The preparation method comprises the followingsteps of (1) esterification reaction: performing esterification reaction on beta-methylglutaric acid and methyl alcohol to obtain beta-dimethyl methylglutarate; (2) alkaline hydrolysis reaction: adding a barium hydroxide methyl alcohol solution into the obtained beta-dimethyl methylglutarate to generate barium salt of the monomethyl 3-methylglutarate; (3) finished product preparation: performing hydrochloric acid acidification, diethyl ether extraction and rectification and purification on the barium salt of the monomethyl 3-methylglutarate to obtain the monomethyl 3-methylglutarate. The prepared monomethyl 3-methylglutarate has the advantages of high yield, high purity and high mono-esterification selectivity. The preparation method is scientific and reasonable; simplicity is realized; the implementation is easy; the method is suitable for industrial mass production.
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Paragraph 0033; 0034; 0046-0048; 0053; 0057-0063; 0068-0074
(2018/09/08)
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- Enantioselective acyl-transfer catalysis by fluoride ions
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The asymmetric nucleophilic catalysis by fluoride ions at a carbon-based electrophile has been demonstrated for the first time. Using a library of ad hoc designed bifunctional phase-transfer catalysts in which both the anion and the cation are directly involved in the reaction, the desymmetrisation of meso-succinic and -glutaric anhydrides is possible.19F NMR spectroscopic studies support the intermediacy of an acyl fluoride intermediate.
- Craig, Ryan,Litvajova, Mili,Cronin, Sarah A.,Connon, Stephen J.
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supporting information
p. 10108 - 10111
(2018/09/18)
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- Method for synthesizing muscone by utilizing beta-monomethyl methylglutarate
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The invention discloses a method for synthesizing muscone by utilizing beta-monomethyl methylglutarate. According to the method, beta-monomethyl methylglutarate and alpha,omega-dodecanedioic acid monomethyl ester respectively prepared through a heteropoly acid catalytic transesterification method are used as raw materials, and Kolbe electrolysis, acyloin condensation and reduction reaction are performed to prepare the muscone. The method of the present invention has advantages of high raw material utilization rate, mold condition, easy control and environmental protection, and is suitable for industrial production .
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Paragraph 0021; 0022
(2017/12/05)
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- Two potent OXE-R antagonists: Assignment of stereochemistry
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5-Oxo-6,8,11,14-eicosatetraenoic acid (5-oxo-ETE) is formed by the oxidation of 5-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HETE), which is a major metabolite of enzymatic oxidation of arachidonic acid (AA). 5-Oxo-ETE is the most potent lipid chemoattractant for human eosinophils. Its actions are mediated by the selective OXE receptor, which is therefore an attractive target in eosinophilic diseases such as allergic rhinitis and asthma. Recently, we have reported two excellent OXE receptor antagonists that have IC50 values at low nanomolar concentrations. Each of these antagonists has a chiral center, and the isolation of the individual enantiomers by chiral high-performance liquid chromatography (HPLC) revealed that in each case one enantiomer is over 300 times more potent than the other. To unambiguously assign the stereochemistry of these enantiomers and to provide access to larger amounts of the active compounds for biological testing, we report here their total synthesis.
- Patel, Pranav,Reddy, Chintam Nagendra,Gore, Vivek,Chourey, Shishir,Ye, Qiuji,Ouedraogo, Yannick P.,Gravel, Sylvie,Powell, William S.,Rokach, Joshua
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supporting information
p. 815 - 819
(2014/08/05)
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- Highly enantioselective desymmetrization of meso anhydrides by a bifunctional thiourea-based organocatalyst at low catalyst loadings and room temperature
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(Chemical Equation Presented) Bifunctional (thio)urea-based cinchona alkaloid derivatives have been shown to promote highly efficient enantioselective desymmetrization reactions of meso anhydrides. The most selective of these catalysts is capable of the enantioselective methanolysis of succinic and glutaric anhydride derivatives to form hemiester products with >90% yield and enantiomeric excess at 1 mol % loading and ambient temperature.
- Peschiulli, Aldo,Gun'ko, Yurii,Connon, Stephen J.
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p. 2454 - 2457
(2008/09/19)
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- An efficient asymmetric desymmetrization of prochiral glutaric anhydrides with SuperQuat chiral oxazolidin-2-ones
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The asymmetric desymmetrization of 3-substituted glutaric anhydrides 1 bearing silyl, aryl and alkyl groups with the lithium salt of chiral oxazolidin-2-ones has been studied. The effects of the substituents at the 4- and 5-positions of the oxazolidin-2-ones on the diastereoselectivity of the anhydride opening were studied in detail. A SuperQuat chiral oxazolidin-2-one 2e with 5,5-diaryl substituents showed optimum selectivity.
- Chaubey, Narendra,Date, Sonali M.,Ghosh, Sunil K.
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experimental part
p. 2721 - 2730
(2009/04/07)
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- Synthesis and spectroscopic characterization of [5-13C]- and [6-13C]ubiquinone-10 for studies of bacterial photosynthetic reaction centers
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This paper presents the synthesis and characterization by mass spectrometry and NMR spectroscopy of [2-13C]- and [3-13C]ubiquinone-0 and of [5-13C]- and [6-13C]ubiquinone-10. A scheme based on the synthetic approach to [5-13C]ubiquinone-10 has been worked out for the synthesis of ubiquinones 13C-labeled at any individual position and at every combination of positions in the quinone ring. The [5-13C]- and [6-13C]ubiquinone-10 isotopomers were incorporated into the QA-site of the photosynthetic reaction center of Rhodobacter sphaeroides R-26. Magic angle spinning NMR subsequently revealed an unperturbed 6-position, while the signal of the 5-position was absent. These results corroborate the recently reported detection of an asymmetric binding of QA with a dynamic perturbation involving the 4-carbonyl functionality.
- Boers, Rutger B.,Gast, Peter,Hoff, Arnold J.,De Groot, Huub J. M.,Lugtenburg, Johan
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p. 189 - 202
(2007/10/03)
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- Lactam and cyclic urea derivatives useful as alpha 1a adrenoceptor antagonists
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Lactam and cyclic urea derivatives and their pharmaceutically acceptable salts are disclosed. The synthesis of these compounds and their use as alpha 1aadrenergic receptor antagonists is also described. One application of these compounds is in the treatment of benign prostatic hyperplasia. These compounds are typically selective in their ability to relax smooth muscle tissue enriched in the alpha 1areceptor subtype without at the same time inducing hypotension. One such tissue is found surrounding the urethral lining. Therefore, one utility of the instant compounds is to provide acute relief to males suffering from benign prostatic hyperplasia, by permitting less hindered urine flow. Another utility of the instant compounds is provided by combination with a human 5-alpha reductase inhibitory compound, such that both acute and chronic relief from the effects of benign prostatic hyperplasia can be achieved.
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- A NEW FATTY ACID METHYL ESTER AND OTHER BIOLOGICALLY ACTIVE COMPOUNDS FROM ASPERGILLUS NIGER
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Methyl 3-methyl-8-hydroxy-4-decenoate, a new C10 fatty acid methyl ester, was isolated and characterized from Aspergillus niger var.Tieghem.The chemical synthesis of this compound has also been achieved.Other compounds characterized from A. niger were phenylethanol, phenylacetic acid, phenoxyacetic acid, p-methoxyphenylacetic acid, mannitol and citric acid.All compounds except mannitol, inhibited the germination of cress and lettude seeds.Antifungal bioassay of the above compounds on Cladosporium herbarum showed activity except for the C10 fatty acid methyl ester, mannitol and citric acid.Key Word Index - Aspergillus niger; fungus; methyl 3-methyl-8-hydroxy-4-decenoate; phenylethanol; phenylacetic acid; phenoxyacetic acid; p-methoxyphenylacetic acid; mannitol; citric acid.
- Nair, Muraleedharan G.,Burke, Basil A.
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p. 3169 - 3174
(2007/10/02)
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- SYNTHESIS OF THE TWO ENANTIOMERS OF THE SEX PHEROMONE OF DIABROTICA UNDECIMPUNCTATA HOWARDI AND OF CHIRAL PRECURSORS OF OTHER PHEROMONES STARTING FROM ENENTIOMERICALLY PURE METHYL HYDROGEN (R)-3-METHYLGLUTARATE
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Readily available methyl hydrogen (R)-3-methylglutarate (2) is a useful chiral building block for the synthesis of several biologically active compounds.Enantiomerically pure (R)-2 has been employed to synthesize stereospecifically each of the two enantiomers, 1a and 1b, of 10-methyl-2-tridecanone,the sex pheromone of the southern corn rootworm, Diabrotica undecimpunctata howardi Barber.Compound (R)-2 has been also used to prepare 99percent optically pure (R)-3-methyl-1-pentanol (6) and enantiomerically pure (R)-5-methyl-i-tricosyne (7).These compounds are useful building blocks suitable for the further elaboration to other chiral insect pheromones.
- Rossi, Renzo,Carpita, Adriano,Chini, Marco
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p. 627 - 634
(2007/10/02)
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