- Organomagnesium Based Flash Chemistry: Continuous Flow Generation and Utilization of Halomethylmagnesium Intermediates
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The generation of highly unstable chloromethylmagnesium chloride in a continuous flow reactor and its reaction with aldehydes and ketones is reported. With this strategy, chlorohydrins and epoxides were synthesized within a total residence time of only 2.6 s. The outcome of the reaction can be tuned by simply using either a basic or an acidic quench. Very good to excellent isolated yields, up to 97%, have been obtained for most cases (30 examples).
- Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
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- Azidolysis of epoxides catalysed by the halohydrin dehalogenase from Arthrobacter sp. AD2 and a mutant with enhanced enantioselectivity: an (S)-selective HHDH
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Halohydrin dehalogenase from Arthrobacter sp. AD2 catalysed azidolysis of epoxides with high regioselectivity and low to moderate (S)-enantioselectivity (E?=?1–16). Mutation of the asparagine 178 to alanine (N178A) showed increased enantioselectivity towards styrene oxide derivatives and glycidyl ethers. Conversion of aromatic epoxides was catalysed by HheA-N178A with complete enantioselectivity, however the regioselectivity was reduced. As a result of the enzyme-catalysed reaction, enantiomerically pure (S)-β-azido alcohols and (R)-α-azido alcohols (ee???99%) were obtained.
- Mikleu?evi?, Ana,Primo?i?, Ines,Hrenar, Tomica,Salopek-Sondi, Branka,Tang, Lixia,Elenkov, Maja Majeri?
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p. 930 - 935
(2016/09/13)
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- Manganese(II)/Picolinic Acid Catalyst System for Epoxidation of Olefins
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An in situ generated catalyst system based on Mn(CF3SO3)2, picolinic acid, and peracetic acid converts an extensive scope of olefins to their epoxides at 0 °C in 5 min, with remarkable oxidant efficiency and no evidence of radical behavior. Competition experiments indicate an electrophilic active oxidant, proposed to be a high-valent Mn = O species. Ligand exploration suggests a general ligand sphere motif contributes to effective oxidation. The method is underscored by its simplicity and use of inexpensive reagents to quickly access high value-added products.
- Moretti, Ross A.,Du Bois,Stack, T. Daniel P.
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supporting information
p. 2528 - 2531
(2016/07/06)
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- Total synthesis of hibispeptin A via Pd-catalyzed C(sp3)-H arylation with sterically hindered aryl iodides
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To access the key Ile-Hpa pseudodipeptide motif in hibispeptins, a series of bidentate carboxamide-based auxiliary groups have been explored to facilitate the palladium-catalyzed arylation of unactivated γ-C(sp3)-H bonds of Ile precursor with a
- He, Gang,Zhang, Shu-Yu,Nack, William A.,Pearson, Ryan,Rabb-Lynch, Javon,Chen, Gong
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supporting information
p. 6488 - 6491
(2015/02/19)
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- DNA-based hydrolytic kinetic resolution of epoxides
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DNA-bound copper(II) complexes serve as catalysts for the hydrolytic kinetic resolution of 2-pyridyloxiranes in water. Selectivity factors of up to 2.7 were achieved, indicating a chirality transfer of DNA to epoxides via a coordinated metal ion.
- Dijk, Ewold W.,Feringa, Ben L.,Roelfes, Gerard
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scheme or table
p. 2374 - 2377
(2009/04/11)
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- Oxidative cleavage of alkenes catalyzed by a water/organic soluble manganese porphyrin complex
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Tetrakis(4-hydroxyphenyl)porphyrin [TPP-(OH)4] was modified with poly(ethylene glycol) chain as four side arms, such that this compound is soluble in both organic and water solutions. Complexation of this porphyrin with manganese metal ions resulted in the formation of MnCl-TPP-(PEO750)4. This complex proved to be an excellent catalyst for the oxidative cleavage of C{double bond, long}C bonds, yielding the corresponding carbonyl compounds with sodium periodate as an oxidant. Mechanistic pathway for this cleavage is discussed.
- Liu, Shiuh-Tzung,Reddy, K. Venugopal,Lai, Rung-Yi
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p. 1821 - 1825
(2007/10/03)
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- CETP INHIBITORS
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Compounds having the structures of Formula I, including pharmaceutically acceptable salts of the compounds, are CETP inhibitors, and are useful for raising HDL-cholesterol, reducing LDL-cholesterol, and for treating or preventing atherosclerosis: In the compounds of Formula I, B or R2 is a phenyl group which has an ortho aryl, heterocyclic, benzoheterocyclic or benzocycloalky substituent, and one other position on the 5-membered ring has an aromatic, heterocyclic, cycloalkyl, benzoheterocyclic or benzocycloalky substituent connected directly to the ring or attached to the ring through a -CH2-.
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Page/Page column 42-43
(2010/10/19)
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- Studies on cognitive enhancing agents. II. Antiamnestic and antihypoxic activities of 1-aryl-2-(2-aminoethoxy)ethanols
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A series of 2-(2-aminoethoxy)-1-phenylethanols having a variety of N- and phenyl-substitution patterns as well as 5- and 6-membered heteroaryl counterparts of our prototype compound 1 (2-(2-dimethylaminoethoxy)-1- phenylethanol) have been prepared and evaluated for antiamnestic and antihypoxic activities. Compound 3b, the 3-methylphenyl analogue of 1, proved to be significantly more potent than I in reversing electroconvulsive shock- induced amnesia as well as CO2-induced learning-impairment in mice. It exhibited low acute toxicity in mice and afforded a greater brain/serum concentration ratio than 1 after oral administration to rats.
- Ono,Yamafuji,Chaki,Morita,Todo,Maekawa,Kitamura,Tai,Narita
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p. 1488 - 1491
(2007/10/03)
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- Analogues of the dioxolanes dexoxadrol and etoxadrol as potential phencyclidine-like agents. Synthesis and structure-activity relationships
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A series of dioxolane analogues based on dexoxadrol ((4S,6S)-2,2-diphenyl- 4-(2-piperidyl)-1,3-dioxolane) and etoxadrol ((2S,4S,6S)-2-ethyl-2-phenyl-4- (2-piperidyl)-1,3-dioxolane) were prepared and tested for their ability to displace [3H]TCP (1-[1-(2-thienyl)cyclohexyl]piperidine) from PCP (1-(1- phenylcyclohexyl)piperidine) binding sites in rat brain tissue homogenates. Qualitative structure-activity relationships within this series were explored through modifications of the three major structural units of dexoxadrol, the piperidine, 1,3-dioxolane, and aromatic rings of the molecule. N-Alkyl derivatives of dexoxadrol were found to be inactive, as were those analogues where the dioxolane ring was modified. Phenyl-substituted etoxadrol analogues were compared to similarly substituted PCP analogues and distinct differences were found in their structure-activity relationships suggesting that the aromatic rings in these two drug classes interact differently with the PCP binding sites. The replacement of the phenyl ring in etoxadrol by either a 2- or 3-thienyl ring led to compounds with affinity comparable to etoxadrol, and the replacement of the ethyl moiety on etoxadrol's dioxolane ring with propyl (7) or isopropyl (8) led to compounds which were more potent than etoxadrol or PCP. The most potent compound was (2S,4S,6S)-2-ethyl-2-(1- chlorophenyl)-4-(2-piperidyl)-1,3-dioxolane (11), where a chlorine moiety was placed in the ortho position in the aromatic ring of etoxadrol. Its potency was comparable with TCP in vitro.
- Thurkauf,Mattson,Richardson,Mirsadeghi,Ornstein,Harrison Jr.,Rice,Jacobson,Monn
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p. 1323 - 1329
(2007/10/02)
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- Synthesis and β-adrenergic antagonism of 2-(aryloxy)-1-(2-piperidyl)ethanols
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A series of erythro- and threo-2-(aryloxy)-1-(2-piperidyl)ethanol derivatives (3) was synthesized from 2-(2-oxiranyl)pyridine for evaluation as β-antagonists. Most compounds displayed high competitive β-blocking potency, but they lacked significant β
- Mauleon,Pujol,Rosell
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p. 2122 - 2126
(2007/10/02)
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- A NOVEL APPROACH TO FUNCTIONALIZATION OF AZINES. OXIRANYL AND THIIRANYL DERIVATIVES OF PYRIDINE, QUINOLINE AND ISOQUINOLINE
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Convenient methods for synthesis of the oxiranyl and thiiranyl derivatives of pyridine, quinoline and isoquinoline have been elaborated.Oxiranes have been synthesized from corresponding aldehydes with dimethylsulfonium methylide in anhydrous medium.Exchange of the oxygen atom in the oxirane ring on sulfur with potassium thiocyanate gave thiiranylazines.
- Kloc, Krystian,Kubicz, Elzbieta,Mlochowski, Jacek
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p. 2517 - 2522
(2007/10/02)
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