- Novel access to carbonyl and acetylated compounds: The role of the tetra-: N -butylammonium bromide/sodium nitrite catalyst
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A novel aerobic oxidation of alcohols without the use of any oxidants was developed. An equimolar catalytic mixture of tetra-n-butylammonium bromide and sodium nitrite catalyzes the aerobic selective oxidation of benzylic alcohols under oxidant-free, base-free and metal-free conditions. The mild reaction conditions allow oxidation of a wide range of benzylic alcohols, chemo-selectively to their carbonyl compounds (68-93% isolated yields). More importantly, high selectivity among different kinds of alcohols (aromatic vs. aliphatic alcohols, primary vs. secondary alcohols as well as alcohols having neutral rings vs. electron-deficient rings) is available by this approach. The method surprisingly switched over to be an efficient acetylation approach in the case of aliphatic alcohols without the use of any transition metal, phosphorous or other toxic reagents or any need for using toxic acyl halides, sulfonyl halides, anhydrides, etc. by the use of only acetic acid as a reagent.
- Sheykhan, Mehdi,Moafi, Hadi Fallah,Abbasnia, Masoumeh
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p. 51347 - 51355
(2016/06/09)
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- Cross-coupling of nonactivated primary and secondary alkyl halides with aryl Grignard reagents catalyzed by chiral iron pincer complexes
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Iron(III) bisoxazolinylphenylamido (bopa) pincer complexes are efficient precatalysts for the cross-coupling of nonactivated primary and secondary alkyl halides with phenyl Grignard reagents. The reactions proceed at room temperature in moderate to excellent yields. A variety of functional groups can be tolerated. The enantioselectivity of the coupling of secondary alkyl halides is low.
- Bauer, Gerald,Cheung, Chi Wai,Hu, Xile
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p. 1726 - 1732
(2015/06/16)
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- Visible-light-promoted conversion of alkyl benzyl ether to alkyl ester or alcohol via O-α-sp3 C-H cleavage
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A mild and high-yielding visible-light-promoted conversion of alkyl benzyl ethers to the alkyl esters or alkyl alcohols was developed. Mechanistic studies provided evidence for a radical chain reaction involving the homolytic cleavage of O-α-sp3 C-H bonds in the substrate as one of the propagation steps. We propose that α-bromoethers are key intermediates in the transformation.
- Lu, Ping,Hou, Tianyuan,Gu, Xiangyong,Li, Pixu
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p. 1954 - 1957
(2015/04/27)
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- PHOTOALIGNING MATERIALS
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The present invention relates to polymer, homo- or copolymer or oligomer for the photoalignment of liquid crystals, especially for the planar orientation of liquid crystals, comprising a main chain and a side chain, wherein the side chain and/or main chain comprises a polar group, compositions thereof, and its use for optical and electro optical devices, especially liquid crystal devices (LCDs).
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Page/Page column 103
(2013/04/24)
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- PHOTOALIGNING MATERIALS
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The present invention relates to polymer, homo- or copolymer or oligomer, which, when irradiated with polarised light orients perpendicular to the polarization direction of polarized actinic light, for the photoalignment of liquid crystals, especially for the planar orientation of liquid crystals, and which derives from at least one monomer (I), compositions thereof, and its use for optical and electro optical devices, such as, liquid crystal devices (LCDs), especially for planar orientation of liquid crystals.
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Page/Page column 122
(2013/04/24)
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- Halogenation of primary alcohols using a tetraethylammonium halide/[Et 2NSF2]BF4 combination
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The halogenation of primary alcohols is presented. The use of a combination of tetraethylammonium halide and [Et2NSF2]BF4 (XtalFluor-E) allows for chlorination and bromination reactions to proceed efficiently (up to 92% yield) with a wide range of alcohols. Iodination reactions are also possible albeit in lower yields.
- Pouliot, Marie-France,Mahe, Olivier,Hamel, Jean-Denys,Desroches, Justine,Paquin, Jean-Francois
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supporting information
p. 5428 - 5431,4
(2020/10/15)
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- Methoxy- and fluorine-substituted analogs of O-1302: Synthesis and in vitro binding affinity for the CB1 cannabinoid receptor
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Methoxy and fluorine analogs substituted on the terminal carbon of the pentyl chain of N-(piperidinyl)-1-(2,4-dichlorophenyl)-4-methyl-5-(4- pentylphenyl)-1H-pyrazole-3-carboxamide (O-1302) were synthesized in a multi-step process from 5-phenyl-1-pentanol, which was based on the 1,5-diarylpyrazole core template of N-(piperidinyl)-5-(4-chlorophenyl)-1-(2,4- dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide (SR141716) through condensation of the respective amine with pyrazole carboxylic acid, in order to develop tracers for medical imaging. Their potency for inhibiting the binding of the CB1 antagonist [3H]SR141716 was evaluated with the aim of developing positron emission tomography (PET) ligands for the cerebral cannabinoid CB1 receptor. These analogs bearing a piperidinyl carboxamide at the C3 of the pyrazole ring exhibited affinities comparable to those of the CB1 reference antagonist SR141716, which warrants further investigation using the radiolabeled form for biological imaging studies. A morpholine ring substituted at the C3 of the pyrazole ring resulted in a reduction of the CB1 affinity.
- Tobiishi, Shintaro,Sasada, Toru,Nojiri, Yumiko,Yamamoto, Fumihiko,Mukai, Takahiro,Ishiwata, Kiichi,Maeda, Minoru
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p. 1213 - 1217
(2008/09/16)
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- Room-temperature Hiyama cross-couplings of arylsilanes with alkyl bromides and iodides
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The first method for achieving Hiyama couplings of unactivated alkyl bromides and iodides is reported. The desired carbon-carbon bond formation proceeds under mild conditions (room temperature) with good functional-group tolerance. Copyright
- Lee, Jae-Young,Fu, Gregory C.
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p. 5616 - 5617
(2007/10/03)
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- Highly efficient, general procedure for the preparation of alkylzinc reagents from unactivated alkyl bromides and chlorides
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(Matrix presented) Alkylzinc bromides have been efficiently prepared by the direct insertion of zinc metal (dust, powder, granule, shot), activated with 1-5 mol % I2, into alkyl bromides in a polar aprotic solvent. The zinc reagents thus formed undergo Ni- and Pd-catalyzed cross-coupling with aryl halides to produce functionalized alkylarenes in excellent yields.
- Huo, Shouquan
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p. 423 - 425
(2007/10/03)
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- Neue Cobalt- und Eisen-katalysierte Reaktionen mit Organozinkverbindungen
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Keywords: Acylierungen; Allylierungen; Cobaltverbindungen; Katalyse; Zinkverbindungen
- Reddy, C. Kishan,Knochel, Paul
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p. 1812 - 1813
(2007/10/03)
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- Effects of Substrate Structure on Lipase-Catalyzed Transesterification of ω-Substituted 1-Alkanols in Organic Solvents.
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Lipase-catalyzed transesterification of ω-phenyl-1-alkanols with vinyl acetate in organic solvents have been investigated.Benzyl alcohol is the most reactive substrate among those studied.It is proposed that a lipase from Pseudomonas cepacia (PCL) has a domain to attract an aromatic moiety of a substrate.
- Nakamura, Kaoru,Kawasaki, Masashi,Ohno, Atsuyoshi
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p. 3053 - 3056
(2007/10/02)
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- Synthesis of long chain ω-aralkylbromides
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1-Iodo-4-acetoxybutane is a useful 4 carbon synthon which reacts selectively with Grignards under copper catalysis. The immediate products are converted to bromides.
- Forth,Smith
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p. 951 - 959
(2007/10/02)
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- Topically active carbonic anhydrase inhibitors. 4. [(hydroxyalkyl)sulfonyl]benzene and [(hydroxyalkyl)sulfonyl]thiophenesulfonamides
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For several decades a tantalizing goal for the treatment of primary open-angle glaucoma has been the development of a topically active carbonic anhydrase inhibitor. Recent results from several research groups indicate that considerable progress has been made toward this objective. In this report, we present the design and synthesis of (hydroxyalkyl)sulfonyl-substituted benzene- and thiophenesulfonamides. These compounds exhibit inhibition of carbonic anhydrase II in the nanomolar range and lower intraocular pressure in the α-chymotrypsinized rabbit model of ocular hypertension after topical instillation.
- Shepard,Graham,Hudcosky,Michelson,Scholz,Schwam,Smith,Sondey,Strohmaier,Smith,Sugrue
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p. 3098 - 3105
(2007/10/02)
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- Cob(I)alamin als Katalysator. 6. Mitteilung . Bildung und Fragmentierung von Alkylcobalaminen, ein Gleichgewichtsprozess zwischen nukleophiler Addition und reduktiver Fragmentierung
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Isolated olefines can be saturated using catalytic amounts of cob(I)alamin in aqueous acetic acid; as electron source an excess of zinc dust is added to the solution containing the homogeneous catalyst.During this overall hydrogenation of isolated double bonds intermediate alkylcobalamins are formed (compare e.g.Schemes 2, 4, 5, 7 and 12).Clear evidence is presented that the nucleophilic attack on the isolated double bond is carried out by cob(I)alamin and not by cob(II)alamin also present in the system (see Scheme 3b and 3c).As this catalytic saturation of olefins depends on the pH of the solution, characterized by a slow reaction at pH=7.0 compared to the same reduction in aqueous acetic acid (see Scheme 2, 2 -> 4, and Scheme 3a), it is reasonable to accept the participation of an electrophilic attack by a proton during the generation of alkylcobalamins. - We use the term nucleophilic addition to describe the formation of alkylcobalamins from a proton, an olefin and cob(I)alamin (compare Schemes 4-7 and 12).A special sequence of experiments showed the nucleophilic addition to beregioselective.Preferentially the higher substituted alkylcobalamin revealed to be produced.Therefore, the nucleophilic addition of cob(I)alamin follows the Markownikoff rule (compare chap. 4: formation and fragmentation of β-hydroxyalkylcobalamins).Under the reaction conditions applied the intermediate alkylcobalamins can be present in base-on and base-off forms.They are known to exist as octahedral complexes and might also be stable to some extent as tetragonal-pyramidal species.In addition the base-off forms can partially be protonated at the dimethylbenzimidazole moiety in aqueous acetic acid (compare Scheme 12).From this equilibrium of intermediate alkylcobalamins three modes of decay disclosed to be possible: (i) The reductive fragmentation leading to an olefin, a proton, and cob(I)alamin is the formal retro-reaction of the nucleophilic addition (see Schemes 2, 4 and 6-12).This equilibrium of an associated alkylcobalamin and the corresponding dissociation products revealed to be a fast process compared to the reductive cleavage of the Co, C-bond cited below (s. (iii)). (ii) As the second reaction pattern an oxidative fragmentation producing an olefin, a hydroxy anion (or water, respectively) and cob(III)alamin has been observed (see Schemes 7, 8, 10 and 12). (iii) The slow reductive cleavage of the Co, C-bond, initiated by addition of electrons (see ), was the third reaction path observed (see Schemes 2, 4-8 and 10-12. - The stereochemistry of the three transformations originating from the intermediate alkylcobalamins is unknown up to now.The antiperiplanar pattern of the fragmentation reactions presented in the Schemes has been chosen arbitrarily (see e.g.Scheme 12).
- Fischli, Albert,Mueller, Peter Michael
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p. 529 - 554
(2007/10/02)
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