- A short and efficient asymmetric synthesis of (-)-frontalin, (-)-exo-isobrevicomin and a volatile contributor of beer-aroma
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The natural products, (-)-frontalin and (+)-exo-isobrevicomin were synthesized employing Sharpless asymmetric epoxidation and ZrCl 4-catalyzed intramolecular acetalization as the key steps. (-)-Frontalin was synthesized in three steps with a 61
- Singh, Surendra,Guiry, Patrick J.
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- (R)-(2-METHYLOXIRAN-2-YL)METHYL 4-BROMOBENZENESULFONATE
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The present invention relates to compound of formula (I), wherein R1 is chloro, bromo iodo or a brosylate group. The present invention also relates to methods of making this compound and its use in carrying out organic transformations.
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Page/Page column 13; 14; 15
(2020/11/13)
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- Asymmetric total synthesis of naturally occurring spirocyclic tetranorsesquiterpenoid lanceolactone A
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Asymmetric total synthesis of naturally occurring γ-butenolide containing [4.4]spiro-tetrahydrofuran lanceolactone A has been reported in the present work. Bimetallic ("Pd-Cu") cascade cyclization was the crucial reaction employed for the construction of the γ-butenolide framework of the natural product. Subsequently, iodocyclization and reductive deiodination through a transfer hydrogenation reaction were applied to access the target molecule in an efficient manner.
- Acharyya, Ranjan Kumar,Nanda, Samik
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p. 5027 - 5035
(2018/07/25)
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- SUBSTITUTED AMINOBUTYRIC DERIVATIVES AS NEPRILYSIN INHIBITORS
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In one aspect, the invention relates to compounds having the formula: where R1, R2a, R2b, R3-R6, a, b, Z, and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.
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Paragraph 0218
(2016/02/29)
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- Using an asymmetric flow reactor sharples
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PROBLEM TO BE SOLVED: To provide a method for efficiently progressing a Sharpless asymmetric epoxidation even without adding molecular sieves. SOLUTION: The method for producing an optically active epoxyalcohol compound includes mixing an allyl alcohol compound, a titanium tetraalkoxide in a catalytic amount, an optically active tartaric acid ester in a catalytic amount, and an oxidizing agent, in a solvent by using a flow-type reactor (flow reactor). The oxidizing agent is preferably tert-butyl hydroperoxide or cumene hydroperoxide. COPYRIGHT: (C)2013,JPOandINPIT
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Paragraph 0042-0046
(2019/05/21)
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- CARBAZOLE-CONTAINING AMIDES, CARBAMATES, AND UREAS AS CRYPTOCHROME MODULATORS
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The subject matter herein is directed to carbazole-containing amide, carbamate, and urea derivatives and pharmaceutically acceptable salts or hydrates thereof of structural formula I wherein the variable R1, R2, R3, R4, R5, R6, R7, A, D, E, G, J, L, M, Q, a, and b are accordingly described. Also provided are pharmaceutical compositions containing the compounds of formula I to treat a Cry-mediated disease or disorder, such as diabetes, complications associated with diabetes, Cushing's syndrome, NASH, NAFLD, asthma, and COPD.
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Paragraph 0350
(2015/10/28)
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- Total synthesis of seco-plakortolide e and (-)-ent-plakortolide I: Absolute configurational revision of natural plakortolide i
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A first total synthesis of (-)-ent-plakortolide I and seco-plakortolide E was accomplished from (S)-2-methylglycidol. The relevant key reactions involve a diastereoselective Mukaiyama aldol reaction, a regioselective hydroperoxysilylation, and elaboration of the 1,2-dioxane ring by intramolecular Michael addition of a hydroperoxide group to a butenolide. This synthesis allowed the revision of the absolute configuration of plakortolide I and structural revision of plakortolide E.
- Barnych, Bogdan,Vatele, Jean-Michel
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supporting information; experimental part
p. 564 - 567
(2012/03/26)
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- SYNTHETIC INTERMEDIATE OF OXAZOLE COMPOUND AND METHOD FOR PRODUCING THE SAME
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An object of the present invention is to provide a method for producing an oxazole compound in a high yield. The object can be achieved by a compound represented by Formula (11): wherein R1 is a hydrogen atom or lower-alkyl group; R2
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Page/Page column 41-42
(2011/08/21)
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- 1-SUBSTITUTED 4-NITROIMIDAZOLE COMPOUND AND PROCESS FOR PRODUCING THE SAME
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The present invention relates to a 1-substituted-4-nitroimidazole compound represented by the general formula (1) or a salt thereof, (wherein R is a hydrogen atom, a lower alkoxy group-substituted lower alkyl group, a phenyl-lower alkoxy group-substituted lower alkyl group, a cyano-substituted lower alkyl group, a phenyl-lower alkyl group which may have lower alkoxy groups as the substituents in the phenyl ring or a group of the formula -CH2RA; X is a halogen atom or a group of the formula -S(O)n-R1) and method for preparing the same. The compound of the formula (1) is a useful compound as an intermediate for synthesis of various pharmaceutical and agricultural chemicals, particularly, as intermediates for antitubercular agents.
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Page/Page column 47-48
(2010/02/12)
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- Chemo- and stereoselectivity in titanium-mediated regioselective ring-opening reaction of epoxides at the more substituted carbon
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Chemo- and stereoselectivity in the ring-opening reaction of epoxides with a reagent prepared from allylmagnesium halide and chlorotitanium triphenoxide is described. It has been proven that the allylating reagent can also be used for the reaction of epoxides bearing a tert-butyl ester, amide, or acetal moiety, and that the epoxide cleavage regioselectively takes place at the more substituted carbon in all cases. Interestingly, while the reaction of acyclic 2,2,3-trialkyl epoxides or 3,3-disubstituted 2,3-epoxy alcohol derivatives with the allyltitanium reagent yielded the allylated products as an almost 1:1 diastereomixture, the ring-opening reaction of 2-substituted 2,3-epoxy alcohol derivatives stereospecifically proceeded through the anti pathway. The latter reaction is extremely useful for asymmetric construction of quaternary carbon centers.
- Tanaka, Tetsuaki,Hiramatsu, Kei,Kobayashi, Yasutaka,Ohno, Hiroaki
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p. 6726 - 6742
(2007/10/03)
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- An alternative approach to (S)- and (R)-2-methylglycidol O-benzyl ether derivatives
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This report describes the gram scale synthesis of (S)- and (R)-2,2,4-trimethyl-4-(hydroxymethyl)-1,3-dioxolanes using the Sharpless asymmetric dihydroxylation (AD) of the Weinreb amide of 2-methyl-2-propenoic acid. The 2-methylglycerol acetonides resultan
- Avenoza, Alberto,Cativiela, Carlos,Peregrina, Jesus M.,Sucunza, David,Zurbano, Maria M.
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p. 1383 - 1388
(2007/10/03)
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- Mapping the substrate selectivity of new hydrolases using colorimetric screening: Lipases from Bacillus thermocatenulatus and Ophiostoma piliferum, esterases from Pseudomonas fluorescens and Streptomyces diastatochromogenes
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Recent advances in biochemistry and molecular biology have simplified the discovery and preparation of new hydrolases. Although these hydrolases might solve problems in organic synthesis, measuring their selectivity, especially enantioselectivity, remains tedious and time consuming. Recently, we developed a colorimetric screening method to measure the enantioselectivity of hydrolases. Here we apply this rapid screening method to map the substrate selectivity of four new hydrolases: lipases from the thermophilic Bacillus thermocatenulatus (DSM 730, BTL2) and a filamentous fungus Ophiostoma piliferum (NRRL 18917, OPL) and esterases from two bacteria, Pseudomonas fluorescens (SIK-W1, esterase I, PFE) and Streptomyces diastatochromogenes (Tue 20, SDE). We screened a general library of 29 substrates and a chiral library of 23 pairs of enantiomers. All four hydrolases catalysed the hydrolysis of unnatural substrates, but the two lipases accepted a broader range of substrates than the two esterases. As expected, the two lipases favoured more hydrophobic substrates, while the two esterases showed a preference for smaller substrates. Several moderately enantioselective reactions were identified for the solketal esters: BTL2, butyrate, E = 7.9 (R); octanoate, E = 4.9 (R) and 3-bromo-2-methyl propionate methyl esters, PFE, E = 12 (S); SDE, E = 5.6 (S). OPL showed low enantioselectivity toward all substrates tested. The current colorimetric screen could not measure the selectivity for several slow-reacting substrates. Traditional screening identified high enantioselectivity of BTL2 and PFE toward one of these slow substrates, 1-phenylethyl acetate (E>50).
- Liu, Andrew Man Fai,Somers, Neil A.,Kazlauskas, Romas J.,Brush, Terry S.,Zocher, Frank,Enzelberger, Markus M.,Bornscheuer, Uwe T.,Horsman, Geoff P.,Mezzetti, Alessandra,Schmidt-Dannert, Claudia,Schmid, Rolf D.
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p. 545 - 556
(2007/10/03)
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- Total synthesis of (+)-conagenin
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The first total synthesis of (+)-conagenin, a novel immunomodulator produced by Streptomyces roseosporus, has been achieved in highly stereo- and enantioselective manner. The carboxylic acid moiety was synthesized starting with asymmetric aldor reaction of propiophenone with acetaldehyde followed by in situ syn-selective NaBH4 reduction. The amin acid moiety was synthesized based upon Et2AlCl catalyzed cyclization of the epoxy trichloroacetimidate prepared from (S)-methylglycidol. Condensation of both moieties and alkaline hydrolysis led to (+)-conagenin.
- Hatakeyama, Susumi,Fukuyama, Hiroko,Mukugi, Yasuko,Irie, Hiroshi
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p. 4047 - 4050
(2007/10/03)
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- A direct HPLC method for the determination of enantiomeric excess of some highly enantiomerically enriched derivatives of chiral glycidols
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A newly developed HPLC method which requires no derivatization is used to determine accurately the enantiomeric purity of some glycidol-based derivatives that have been enantiomerically enriched by recrystallization or lipase-catalyzed kinetic resolution after the Sharpless Asymmetric Epoxidation.
- Chen, Jian
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p. 7663 - 7666
(2007/10/02)
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- Preparation of C-4 alkylated dideoxyribosides: Potential precursors to a novel series of nucleosides
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Methallyl alcohol can be converted in five simple operations (alkylation, epoxidation, alkynyl-coupling, hydroboration/oxidation, cyclization) to C-5 protected, chiral, non-racemic dideoxyribosides containing an alkyl appendage at the C-4 site.
- Lipshurtz,Sharma,Dimock,Behling
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p. 191 - 195
(2007/10/02)
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- A convenient gas chromatographic method for the optical purity determination of chiral epoxy alcohols
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Short-chain aliphatic epoxy alcohols can be readily resolved without derivatization on a capillary gc column coated with permethylated hydroxypropyl derivative of α-cyclodextrin.
- Dougherty,Liotta,Mondimore,Shum
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p. 4389 - 4390
(2007/10/02)
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- SYNTHESIS OF NATURAL AND UNNATURAL FRONTALIN
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(S)-(-)- and (R)-(+)-Frontalin were synthesized, respectively, in high enantiomer excess from β-methallyl alcohol (2) by three-step procedure; (i) asymmetric epoxidation of 2, (ii) the epoxide opening with homoallylmagnesium bromide, and (iii) Pd(II)-catalyzed intramolecular acetalization.
- Hosokawa, Takahiro,Makabe, Yoshiki,Shinohara, Toru,Murahashi, Shun-Ichi
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p. 1529 - 1530
(2007/10/02)
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- Synthesis of (1S)-(-)-Frontalin
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The aggregation pheromone 1 of the southern pine beetle Dendroctonus frontalis has been synthesized in high optical yield starting from (2R)-2-methyl-2-epoxy-1-propanol (4) which is obtained from methallyl alcohol (3) via enantioselective epoxidation according to Sharpless.
- Meister, Christoph,Scharf, Hans-Dieter
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p. 913 - 921
(2007/10/02)
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