- Stereospecific Synthesis of Substituted Aziridines by a Crystal-to-Crystal Photodenitrogenation of δ2-1,2,3-Triazolines
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Crystalline cis- or trans-δ2-1,2,3-triazolines prepared by highly stereospecific and regioselective hydrogen bonding-catalyzed dipolar cycloaddition of activated cis- or trans-alkenes with aryl azides undergo a highly stereospecific photodenitrogenation to form the corresponding cis- or trans- azidirines in high chemical yields. While examples involving disubstituted and trisubstituted triazolines highlight steric challenges encountered in the dipolar cycloaddition reaction, the stereochemical control exerted by the crystalline lattice is enhanced by bulky substituents in the triazoline precursors to generate aziridines photochemically.
- Chung, Tim S.,Lopez, Steven A.,Houk,Garcia-Garibay, Miguel A.
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- PREPARATION OF TRIFLUOROMETHYLATED ALLYLIC ALCOHOLS FROM TRIFLUOROACETALDEHYDE AND ORGANOMETALLIC COMPOUNDS
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A number of allylic alcohols bearing a trifluoromethyl group at the α- or γ-position, and α-trifluoromethylated γ-enols and -ynols were prepared by the reaction of trifluoroacetaldehyde with a variety of organometallic compounds.Most of the Reformatsky- or Grignard-type reactions required promotion by ultrasonic irradiation.
- Ishikawa, Nobuo,Koh, Moon Gyu,Kitazume, Tomoya,Choi, Sam Kwon
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- Stereoselective aldol reaction of glutarimides using pseudo C2 symmetry
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(Figure presented) The boron aldol reaction of β-substituted glutaric imldes bearing an oxazolidinone-based auxiliary proceeds with excellent diastereoselectivity; switching the tertiary amine employed between /-Pr 2EtN or Et3N affor
- Watanabe, Yohsuke,Yamazaki, Takashi,Kubota, Toshio
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- NMR at earth's magnetic field using para-hydrogen induced polarization
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A method to achieve NMR of dilute samples in the earth's magnetic field by applying para-hydrogen induced polarization is presented. Maximum achievable polarization enhancements were calculated by numerically simulating the experiment and compared to the experimental results and to the thermal equilibrium in the earth's magnetic field. Simultaneous 19F and 1H NMR detection on a sub-milliliter sample of a fluorinated alkyne at millimolar concentration (~1018 nuclear spins) was realized with just one single scan. A highly resolved spectrum with a signal/noise ratio higher than 50:1 was obtained without using an auxiliary magnet or any form of radio frequency shielding.
- Hamans, Bob C.,Heerschap, Arend,Andreychenko, Anna,Wijmenga, Sybren S.,Tessari, Marco
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- Cobalt-Catalyzed Diastereo- And Enantioselective Reductive Allyl Additions to Aldehydes with Allylic Alcohol Derivatives via Allyl Radical Intermediates
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Catalytic generation of ambiphilic π-allyl-metal complexes and their utility in enantioselective transformations constitutes a powerful approach for introduction of allyl groups to a molecule. Herein an unprecedented cobalt-catalyzed highly site-, diastereo-, and enantioselective protocol for stereoselective formation of nucleophilic allyl-Co(II) complexes followed by addition to aldehydes is presented. The reaction features diastereo- and enantioconvergent conversion of easily accessible allylic alcohol derivatives to diversified enantioenriched homoallylic alcohols with a remarkably broad scope of allyl groups that can be introduced. Mechanistic studies indicated that allyl radical intermediates were involved in this process. These new discoveries establish a new strategy for development of enantioselective transformations through capture of radicals by chiral Co complexes, pushing forward the frontier of Co complexes for enantioselective catalysis.
- Wang, Lei,Wang, Lifan,Li, Mingxia,Chong, Qinglei,Meng, Fanke
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supporting information
p. 12755 - 12765
(2021/08/30)
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- PROCESS FOR PREPARATION OF 4,4,4- TRIFLUOROBUT-2-EN-1-OL AND INTERMEDIATE THEREOF
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The present invention provides a process for preparation of 4,4,4- trifluorobut-2-en-1-ol from alkyl 4,4,4-trifluorobut-2-enoate and also provides one step process for preparation of alkyl 4,4,4-trifluorobut-2-enoate from corresponding hydroxy derivative using mild and easily available reagents.
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Page/Page column 11
(2020/07/31)
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- Synthesis method for 4,4,4-trifluoro-crotonates
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The invention relates to a synthesis method for 4,4,4-trifluoro-crotonates. The problems that in the prior art, the conversion rate of 3,3,3-trifluoro-allylene is low, and the selectivity of 4,4,4-trifluoro-crotonates is low are mainly solved. The preparing method for the 4,4,4-trifluoro-crotonates includes the step that the 3,3,3-trifluoro-allylene, materials of carbon monoxide and alcohol and acatalyst composition are subjected to a contact reaction to obtain the 4,4,4-trifluoro-crotonates, wherein the catalyst composition comprises a rhodium complex and a high-valence-metal-cation-ocene diphosphonic compound in the technical scheme; the technical problems are well solved, and the synthesis method can be used for industrial production of the 4,4,4-trifluoro-crotonates.
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Paragraph 0037; 0040; 0041; 0042; 0044; 0049; 0054; 0060
(2019/01/16)
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- Stereospecific photochemistry of Δ2-1,2,3-triazolines in solution and in the solid state: Scope and mechanistic studies
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The stereospecific photochemistry of ten N-aryl-substituted cis- or trans-Δ2-1,2,3-triazolines to form the corresponding cis- or trans-aziridines was investigated both in solution and in the solid-state. We found that photochemical reactions in the solid state are more stereospecific than in solution for the 8 crystalline Δ2-1,2,3-triazolines. Additionally, triplet sensitization for some triazolines results in triplet biradicals, which provide the more thermodynamically favored trans-aziridine regardless of the starting triazoline stereochemistry. Product analyses as a function of temperature and solvent polarity suggest that the electronic excitation of the Δ2-1,2,3-triazolines results in the formation of a 1,3-biradical intermediate.
- Chung, Tim S.,Xue, Yang,Carranza, Alberto,Garcia-Garibay, Miguel A.
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p. 1458 - 1463
(2017/09/23)
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- METHOD FOR PREPARATION OF FLUORO, CHLORO AND FLUOROCHLORO ALKYLATED COMPOUNDS BY HOMOGENEOUS CATALYSIS
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The invention discloses a method for preparation of fluoro, chloro and fluorochloro alkylated compounds by homogeneous Pd catalyzed fluoro, chloro and fluorochloro alkylation with fluoro, chloro and fluorochloroalkyl halides in the presence of di(1-adamantyl)-n-butylphosphine and in the presence of 2,2,6,6-tetramethylpiperidine 1-oxyl.
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Page/Page column 21; 22
(2016/06/01)
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- Decarboxylative and Denitrative Trifluoromethylation for the Synthesis of Cvinyl-CF3 Compounds with Togni (II) Reagent
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A highly efficient dimethylformamide (DMF)-promoted decarboxylative trifluoromethylation of α,β-unsaturated carboxylic acids with Togni (II) reagent under metal-free conditions has been developed. The reactions showed good yields, high stereoselectivities and excellent functional group tolerance. Mechanistic studies confirmed that free-radical processes were involved in this system since the CF3 radical had been clearly trapped by scavengers. This method has been extended to the denitrative trifluoromethylation of β-nitrostyrenes in the presence of an iron(III) catalyst.
- Ma, Jing-Jing,Yi, Wen-Bin,Lu, Guo-Ping,Cai, Chun
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supporting information
p. 3447 - 3452
(2016/01/25)
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- METABOTROPIC GLUTAMATE RECEPTOR 5 MODULATORS AND METHODS OF USE THEREOF
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Compounds that modulate GluR5 activity and methods of using the same are disclosed.
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Page/Page column 90
(2013/02/27)
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- Highly efficient catalytic asymmetric Sulfa-Michael addition of thiols to trans-4,4,4-trifluorocrotonoylpyrazole
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A new protocol for the efficient construction of chiral trifluoromethylated building blocks was developed via organocatalyzed sulfa-Michael addition of thiols to the cost-efficient trans-trifluorocrotonamide. Introducing the pyrazole moiety is crucial to providing H-bond acceptor sites for better activation and hence affording comparable asymmetric induction with that obtained when employing the expensive cis-4,4,4-trifluorocrotonate as the Michael acceptor. Copyright
- Dong, Xiu-Qin,Fang, Xin,Tao, Hai-Yan,Zhou, Xiang,Wang, Chun-Jiang
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supporting information; experimental part
p. 1141 - 1147
(2012/05/20)
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- Synthesis and cytotoxic activity of fluorinated analogues of Goniothalamus lactones. Impact of fluorine on oxidative processes
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Novel fluorinated analogues of goniothalamin 1 and howiinol A 2 have been prepared from trifluorocrotonate derivatives. Trifluoromethyl goniothalamin (R/S) 4 showed a slightly lower activity than 1, while the trifluoromethyl howiinol A 16 exhibited similar activities on several cell lines in the micromolar range. Unlike (R) goniothalamin and howiinol A, trifluoromethyl parent compounds remained unchanged when submitted to biomimetic oxidative systems.
- Dumitrescu, Lidia,Huong, Doan Thi Mai,Hung, Nguyen Van,Crousse, Benoit,Bonnet-Delpon, Danièle
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scheme or table
p. 3213 - 3218
(2010/08/20)
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- Studies on a three-step preparation of β-fluoroalkyl acrylates from fluoroacetic esters
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β-Fluoroalkyl-acrylic esters are valuable building blocks for the synthesis of organofluorine compounds. Although the preparation of several β-fluoroalkyl-acrylates is known, a general and straightforward lab-scale methodology for the preparation of multigram amounts of these compounds from fluoroacetic esters is not available, and the related chemistry has not been investigated in detail. We now describe an optimized three-step protocol relying on: (1) Claisen-type condensation of fluoroacetic esters with ethyl acetate, using LDA as base; (2) reduction of the resulting γ-fluoro-β-keto esters by NaBH4, using toluene or benzene as solvents; (3) P2O5-promoted dehydration of the intermediate γ-fluoro-β-hydroxy esters. The methodology affords preparatively useful yields of the target compounds incorporating only fluorine atoms (CF3, CHF2, C2F5), whereas the γ-halodifluoromethyl (CClF2, CBrF2, CIF2) acrylates could not be obtained in analytically pure form from the dehydration step.
- Jagodzinska, Monika,Huguenot, Florent,Zanda, Matteo
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p. 2042 - 2046
(2007/10/03)
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- Synthesis of trifluoromethylated analogues of β-l-fucofuranose and β-l-4,6-dideoxyxylohexopyranose
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Efficient strategy to trifluoromethylated trans-disubstituted alkene 3 was developed starting from commercially available 4,4,4-trifluoro-3-oxo-butyric acid ethyl ester 12. 6-Deoxy-6,6,6-trifluorosugars 21 and 30 were synthesized from 3 in high stereoselectivity and in a straightforward fashion. The key steps were Sharpless AD reaction, regioselective ring opening of trifluoromethylated cyclic sulfate, Horner-Wadsworth-Emmons reaction and TEMPO oxidation. It was noteworthy that the oxidation of alcohols 20 and 29 followed by deprotection and acetylation gave the single isomer target molecules 21 and 30, respectively.
- Wang, Bing-Lin,Yu, Fei,Qiu, Xiao-Long,Jiang, Zhong-Xing,Qing, Feng-Ling
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p. 580 - 587
(2008/03/14)
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- The effect of fluoromethyl groups on the diastereoselectivity in the electrophilic alkylation
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The effect of fluoromethyl groups on the diastereoselectivity in the electrophilic alkylation is described. In particular, the electrophilic alkylation of enolates with a trifluoromethyl group was proceeded with highly diastereofacial selectivity based on the steric and/or electrostatic effect of substituent with strong electron withdrawing.
- Tamura, Kenji,Yamazaki, Takashi,Kitazume, Tomoya,Kubota, Toshio
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p. 918 - 930
(2007/10/03)
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- Method for making α,β-unsaturated-β-trifluoromethyl-carboxylates and related compounds
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Disclosed are one and two step methods for preparing α,β-unsaturated-β-trifluoromethyl carboxylates and related materials under mild reaction conditions.
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- A method for making alpha, beta-unsaturated-beta-trifluoromethyl-carboxylates
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Disclosed is a method for preparing an α,β-unsaturated-β-trifluoromethyl carboxylate of the formula: wherein X is selected from OR3and NR3R4, comprising contacting a compound of the formula: with a base to produce the α,β-unsaturated compound. The starting material can be prepared by, acylating a compound of the formula: In the above formulas, R,R1,R2,R3and R4have the meanings given in the description.
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- Stereospecific Synthesis of Racemic cis- and trans-6-Trifluoromethylshikimic Acids
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Two 'unnatural' derivatives of shikimic acids, cis- and trans-6-trifluoromethylshikimic acid, have been synthesized in their racemic forms via the base-promoted opening of furan Diels-Alder adducts bearing a CF3 group.The relative stereochemistry of the trans-diastereoisomer has been confirmed by an X-ray analysis of its t-butyl ester.
- Leroy, Jacques,Fischer, Nathalie,Wakselman, Claude
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p. 1281 - 1287
(2007/10/02)
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- Stereoselective Preparation of Ethyl 2,3-Dihydroxy-4,4,4-trifluorobutyrates via Enzymatic Optical Resolution
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Ethyl 2,3-dihydroxy-4,4,4-trifluorobutyrate was prepared in a highly diastereo- as well as enantioselective manner via enzymatic optical resolution followed by chemical transformations with complete retention of their configurations.
- Yamazaki, Takashi,Okamura, Naoko,Kitazume, Tomoya
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p. 521 - 524
(2007/10/02)
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- Process for preparing pyrazolopyridine compounds
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Compounds of the formula (I): STR1 wherein R4 is hydrogen, D is oxygen or NR6, R1, R3, R6, R7 and R8 have defined values, and n is 1 or 2 are produced by internally cyclizing a compound of the formula (XV): STR2 wherein R19 is a value of R1 or hydrogen and, if R19 is hydrogen, reacting the cyclization product with R1 --Br and a weak base such as potassium carbonate.
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- CNS-Depressant pyrazolopyridines
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Compounds of the formula (I): STR1 wherein R1, R3, R4, R7 and R8 are as described herein, D is oxygen or NR6, n is 1 or 2 and the physiologically acceptable salts thereof useful in reducing anxiety in an animal such as man. The compounds are potent anxiolytics having reduced side effects compared to known anxiolytics. Also pharmaceutical compositions, intermediates and methods of treatment and synthesis are described.
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- Pyrazolo[3,4-b]pyridine carboxylic acid esters and their pharmaceutical use
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Compounds of the formula (I): STR1 wherein R1, R3, R4, R5 and R6 have defined values and the N-oxides at the 7-position of the pyrazolo[3,4-b]pyridine ring system and the pharmaceutically-acceptable acid-addition salts thereof, processes for their preparation and use, pharmaceutical compositions, and intermediates for preparing said compounds of the formula (I). The compounds of formula (I) are central nervous system depressants, for example anxiolytic agents.
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- Regioselectivity in the Ring Opening of 2-Alkylcyclopropylmethyl Radicals: the Effect of Electronegative Substituents
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The regioselectivity of the ring-opening of the trans-2-alkylcyclopropylmethyl radical A to give the primary alkyl radicals B, or the secondary alkyl radicals C, has been investigated, where the groups R and/or CXY carry electronegative substituents.All these reactions gave principally the secondary alkyl radicals C, whereas, in the absence of electronegative substituents, ring-opening occurs in favour of the primary alkyl radicals B.This regioselectivity is interpreted in terms of the frontier orbital interactions which are involved.
- Ratier, Max,Pereyre, Michel,Davies, Alwyn G.,Sutcliffe, Roger
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p. 1907 - 1916
(2007/10/02)
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- REACTION OF HYDROXY AND CARBONYL COMPOUNDS WITH SULFUR TETRAFLUORIDE. XII. REACTIONS OF ESTERS OF ALIPHATIC α- AND β-HYDROXY CARBOXYLIC ACIDS WITH SULFUR TETRAFLUORIDE
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The esters of aliphatic and α- and β-hydroxy carboxylic acids react with sulfur tetrafluoride to form the corresponding esters of fluoro carboxylic acids and alkoxycarbonylalkyl fluorosulfites.If electron-withdrawing substituents are introduced at the α position to the carbon atom attached to the hydroxyl group, the reactions of the esters of hydroxy acids with sulfur tetrafluoride take place with substitution of the carbonyl oxygen by two fluorine atoms.
- Motnyak, L. A.,Burmakov, A. I.,Kunshenko, B. V.,Neizvestnaya, T. A.,Alekseeva, L. A.,Yagupol'skii, L. M.
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p. 1063 - 1074
(2007/10/02)
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- HALOGENATED SUBSTITUTED MERCAPTOACYLAMINO ACIDS
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New halogen substituted mercaptoacylamino acids which have the general formula STR1 and basic salts thereof are useful as hypotensive agents.
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- HALOGEN SUBSTITUTED MERCAPTOACYLAMINO ACIDS
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New halogen substituted mercaptoacylamino acids which have the general formula STR1 ARE USEFUL AS HYPOTENSIVE AGENTS.
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