- The β-effect of silicon in the orthogonal geometry
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The inductive contribution to the β-effect of silicon has been investigated through the preparation of 1-(trimethylsilyl)bicyclo[2.2.2]octan-2-ol (5-OH) and its sulfonate derivatives. The dihedral relationship in 5 between the trimethylsilyl group and the
- Lambert, Joseph B.,Liu, Xiaoyang
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- Well-defined Cp*Co(III)-catalyzed Hydrogenation of Carbonates and Polycarbonates
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We herein report the catalytic hydrogenation of carbonates and polycarbonates into their corresponding diols/alcohols using well-defined, air-stable, high-valent cobalt complexes. Several novel Cp*Co(III) complexes bearing N,O-chelation were isolated for the first time and structurally characterized by various spectroscopic techniques including single crystal X-ray crystallography. These novel Co(III) complexes have shown excellent catalytic activity to produce value added diols/alcohols from carbonate and polycarbonates through hydrogenation using molecular hydrogen as sole reductant or iPrOH as transfer hydrogenation source. To demonstrate the developed methodology's practical applicability, we have recycled the bisphenol A monomer from compact disc (CD) through hydrogenation under the established reaction conditions using phosphine-free, earth-abundant, air- and moisture-stable high-valent cobalt catalysts.
- Dahiya, Pardeep,Gangwar, Manoj Kumar,Sundararaju, Basker
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p. 934 - 939
(2020/12/15)
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- NOVEL FUSED BRIDGED BICYCLIC HETEROARYL SUBSTITUTED 6-ALKYLIDENE PENEMS AS POTENT BETA-LACTAMASE INHIBITORS
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A compound of formula (I) or formula (Ia) Wherein R1 , Ra, R2, X, R3 , Y1, y2, A, B and C are as defined herein. Also, pharmaceutical compositions comprising such compounds and excipients, methods of treating bacterial infections comprising administering such compounds, methods for making such compounds and hydrates of such compounds.
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Page/Page column 13
(2011/12/12)
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- The role of hydrogen migration in the mechanism of alcohol elimination from MH+ ions of ethers upon chemical ionization
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An enhanced elimination of alcohol under isobutane CI conditions, resulting in highly abundant [MH - ROH]+ ions, has been observed in several primary and secondary ethers having a tertiary β-position (methine), as compared with those with β-methylene. This elimination exhibits a significant degree of stereospecificity in stereoisomeric 2-methyl-1-methoxycyclohexanes 4 and 1-methoxy-trans-decalins 7, affording more abundant [MH - ROH]+ ions in the cis isomers 4c and 7tc than in their trans counterparts 4t and 7tt. These findings suggest involvement of a 1,2-hydride migration from the β- to α-position in the course of the alcohol elimination from the MH+ ions of the above cis-ethers, resulting in tertiary carbocation structures. The proposed mechanism of alcohol elimination is supported by a considerable deuterium isotope effect detected in β-deuterium-labeled cis-2-methyl-1-methoxycyclohexane and by a CID study of the structures of [MH - ROH]+ ions obtained from cis- and trans-1,2-dialkoxycyclohexanes. Ring contraction by a Meerwein-type rearrangement has also been observed in the latter system.
- Morlender-Vais,Mandelbaum
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p. 1124 - 1132
(2007/10/03)
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- Bicyclic hexahydroaporphine and 1-benzyloctahydroisoquinoline therapeutic compositions and processes for utilizing said compositions
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The invention relates to the method of synthesis of bicyclic hexahydroaporphine compounds which may provide improved therapy for diseases characterized by an increase in intraocular pressure. More specifically, the present invention relates to the prepara
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- Aryl substituted nitrogen heterocyclic antidepressants
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Antidepressant agents having the formula STR1 wherein R1 is a polycycloalkyl group; R2 is methyl or ethyl, X is O; and Y comprises a 5-membered heterocyclic ring having one or two nitrogens.
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- Rearrangements of 6-Bicyclooctyl Cations
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6-Bicyclooctyl cations were generated by nitrous acid deaminations of the amines 12, 14 and by acetolyses of the tosylates 9, 20.The major products are bicyclooctan-exo-6-ol (17), bicyclooctan-exo-2-ol (18), and bicyclooctan-2-
- Brandt, Sigrid,Kirmse, Wolfgang,Moench, Dietmar,Wroblowsky, Heinz-Juergen
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p. 887 - 893
(2007/10/02)
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- BRIDGING STRAIN IN BICYCLIC CARBOCATIONS
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The solvolysis rates and products of 6-exo- and 6-endo-bicyclooctyl toluenesulfonate confirm that differential bridging strain is a major factor in determining the reactivity of epimeric bicyclic sulfonates.
- Grob, Cyril A,Zutter, Ulrich
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p. 2849 - 2852
(2007/10/02)
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