- Stereoselective Vicinal Difunctionalization of Alkynes through a Three-Component Reaction of Alkynes, Sodium Sulfinates, and Togni Reagent
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Stereoselective vicinal difunctionalization of alkynes through trifluoromethylation and sulfonylation via a three-component reaction of alkynes, sodium sulfinates, and Togni reagent under catalyst- and additive-free conditions has been realized. This reaction proceeds at room temperature in dimethyl sulfoxide (DMSO), providing (E)-β-trifluoromethylvinyl sulfones in moderate to good yields. The advantages of this tandem radical process include extremely mild conditions, excellent stereoselectivity, and easy experimental operation. (Figure presented.).
- Xiang, Yuanchao,Li, Yuewen,Kuang, Yunyan,Wu, Jie
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- Base-free Enantioselective C(1)-Ammonium Enolate Catalysis Exploiting Aryloxides: A Synthetic and Mechanistic Study
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An isothiourea-catalyzed enantioselective Michael addition of aryl ester pronucleophiles to vinyl bis-sulfones via C(1)-ammonium enolate intermediates has been developed. This operationally simple method allows the base-free functionalization of aryl esters to form α-functionalized products containing two contiguous tertiary stereogenic centres in excellent yield and stereoselectivity (all ≥99:1 er). Key to the success of this methodology is the multifunctional role of the aryloxide, which operates as a leaving group, Br?nsted base, Br?nsted acid and Lewis base within the catalytic cycle. Comprehensive mechanistic studies, including variable time normalization analysis (VTNA) and isotopologue competition experiments, have been carried out. These studies have identified (i) orders of all reactants; (ii) a turnover-limiting Michael addition step, (iii) product inhibition, (iv) the catalyst resting state and (v) catalyst deactivation through protonation.
- McLaughlin, Calum,Slawin, Alexandra M. Z.,Smith, Andrew D.
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p. 15111 - 15119
(2019/11/05)
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- AZABICYCLO [4.1.0] HEPT - 4 - YL DERIVATIVES AS HUMAN OREXIN RECEPTOR ANTAGONISTS
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This invention relates to azabicyclo[4.1.0]hept-4-yl derivatives and their use as pharmaceuticals.
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Page/Page column 48-49
(2012/07/14)
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- CARBACEPHEM β-LACTAM ANTIBIOTICS
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Carbacephem -lactam antibiotics having structure (I) are disclosed, including stereoisomers, pharmaceutically acceptable salts, esters and prodrugs thereof, wherein Ar1, Ar2, R1 and R2 are as defined herein. The compounds are useful for the treatment of bacterial infections, in particular those caused by methicillin-resistant Staphylococcus spp.
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Page/Page column 92
(2010/04/06)
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- CARBACEPHEM BETA-LACTAM ANTIBIOTICS
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Carbacephem β-lactam antibiotics having chemical structures (I) and (II) are disclosed: including stereoisomers, pharmaceutically acceptable salts, esters and prodrugs thereof, wherein Ar2, R1, R2 and R6 are as defined herein. The compounds are useful for the treatment of bacterial infections, in particular those caused by methicillin-resistant Staphylococcus spp.
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Page/Page column 65; 88
(2010/11/05)
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- Organofluorine compounds and fluorinating agents, Part 26: New reversed nucleosides - Perfluoroalkyl substituted 1,2,3-triazoles linked to D-galactose and D-altrose
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Reversed nucleosides, i.e., fluoroalkyl-substituted 1,2,3-triazoles linked to the C-atom 6 of D-galactose and D-altrose were synthesised by 1,3-dipolar cycloadditions using the monosaccharide azides 8, 11 and the perfluoroalkyl substituted phenyl vinyl sulfones 5-7. The starting material 11, methyl 6-azido-3,4-O-(trichloroethylidene)-2-O-cyclohexylcarbamoyl-6-deoxy-α-D- altropyranoside, was synthesized from methyl 2-O-cyclohexylcarbamoyl-3,4-O-(2,2,2-trichloroethylidene)-α-D- altropyranoside (9), via its 6-iododeoxy derivative 10. The homologous dipolarophiles 5-7, (E)-1-perfluoroalkyl-2-phenylsulfonyl-ethenes with a CF3 (5), n-C4F9 (6), and n-C6F13 (7) group, respectively, were obtained by Wittig-Horner olefination from phosphonate 4 and the corresponding perfluoroalkanals 1-3. Cycloaddition of 6-azido-6-deoxy-1,2:3,4-di-O-isopropylidene-α-D-galactose (8) with the dipolarophiles 5-7 yielded the reversed nucleosides 12-14; altrose azide 11 gave the reversed nucleosides 15 and 16. The products of cycloaddition were deprotected using usual techniques. Thus, the 1-(6-deoxy-1,2:3,4-di-O-isopropylidene-α-D-galactopyranoso-6-yl)-4- perfluoroalkyl-1,2,3-triazoles 13 and 14 were deacetalated by treatment with aqueous trifluoroacetic acid yielding the corresponding 1-(6-deoxy-α-D-galactopyranoso-6-yl)-4-perfluoroalkyl-1,2,3-triazoles 17 and 18. The deprotection of the 1-[methyl 2-O-cyclohexylcarbamoyl-6-deoxy-3,4-O-(2,2,2-trichloroethylidene)-α-D- altropyranosido-6-yl]-4-perfluoroalkyl-1,2,3-triazoles 15 and 16 was made stepwise (hydrodechlorination→deacetalation→decarbamoylation), i.e., the 1-(methyl 6-deoxy-D-altropyranosido-6-yl)-4-perfluoroalkyl-1,2,3-triazoles 23 and 24 were synthesised via the ethylidene acetals 19, 20 and the 1-(methyl 2-O-cyclohexylcarbamoyl-6-deoxy-α-D-altropyranosido-6-yl)-4- perfluoroalkyl-1,2,3-triazoles 21 and 22. For the methyl 6-azido-2-O-cyclohexylcarbamoyl-6-deoxy-3,4-O-(2,2,2-trichloroethylidene)- α-D-altropyranoside (11) an X-ray structure is given.
- Hager, Christian,Miethchen, Ralf,Reinke, Helmut
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p. 135 - 142
(2007/10/03)
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- STUDIES ON ORGANIC FLUORINE COMPOUNDS. LIII. PREPARATION OF FUNCTIONALIZED TRIFLUOROMETHYLATED COMPOUNDS USING 1-PHENYLSULFONYL-3,3,3-TRIFLUOROPROPENE
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Reaction of 1-phenylsulfonyl-3,3,3-trifluoropropene (1) with carbonyl-stabilized enolate anions smoothly proceeded to give the addition products (7) in good yield while with an alkyl-lithium or Grignard reagent the formation of the vinyl anion (8) was one
- Taguchi, Takeo,Tomizawa, Ginjiro,Kawara, Akihiro,Nakajima, Masaharu,Kobayashi, Yoshiro
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p. 171 - 182
(2007/10/02)
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