42432-42-8Relevant articles and documents
Retro-Corey-Chaykovsky Epoxidation: Converting Geminal Disubstituted Epoxides to Ketones
Li, Siqi,Li, Pingfan,Xu, Jiaxi
, (2019/09/13)
Corey-Chaykovsky epoxidation has been widely applied in the conversion of aldehydes and ketones to epoxides with sulfonium and sulfoxonium ylides. The reverse transformation is realized for conversion of geminal disubstituted epoxides to ketones in the presence of DABCO in refluxing mesitylene. The method is a weak basic transformation from epoxides to ketones with loss of a methylene group and can be applied as an alternative strategy of the acid-catalyzed Meinwald rearrangement or oxidation for conversion of epoxides to carbonyl compounds.
Continuous Flow Synthesis of Terminal Epoxides from Ketones Using in Situ Generated Bromomethyl Lithium
Von Keutz, Timo,Cantillo, David,Kappe, C. Oliver
supporting information, p. 10094 - 10098 (2019/12/24)
A scalable procedure for the direct preparation of epoxides from ketones has been developed. The method is based on the carefully controlled generation of (bromomethyl)lithium (LiCH2Br) from inexpensive CH2Br2 and MeLi in a continuous flow reactor. The reaction has shown excellent selectivity for a variety of substrates, including α-chloroketones, which typically fail under classic Corey-Chaykovsky conditions. This advantage has been used to develop a novel route toward the drug fluconazole.
Mild Iridium-Catalysed Isomerization of Epoxides. Computational Insights and Application to the Synthesis of β-Alkyl Amines
Cabré, Albert,Cabezas-Giménez, Juanjo,Sciortino, Giuseppe,Ujaque, Gregori,Verdaguer, Xavier,Lledós, Agustí,Riera, Antoni
supporting information, p. 3624 - 3631 (2019/07/10)
The isomerization of epoxides to aldehydes using the readily available Crabtree's reagent is described. The aldehydes were transformed into synthetically useful amines by a one-pot reductive amination using pyrrolidine as imine-formation catalyst. The reactions worked with low catalyst loadings in very mild conditions. The procedure is operationally simple and tolerates a wide range of functional groups. A DFT study of its mechanism is presented showing that the isomerization takes place via an iridium hydride mechanism with a low energy barrier, in agreement with the mild reaction conditions. (Figure presented.).
Reaction of azides and enolisable aldehydes under the catalysis of organic bases and: Cinchona based quaternary ammonium salts
Destro, Dario,Sanchez, Sandra,Cortigiani, Mauro,Adamo, Mauro F. A.
supporting information, p. 5227 - 5235 (2017/07/11)
Herein we report a two-step sequence for the preparation of amides starting from azides and enolisable aldehydes. The reaction proceeded via the formation of triazoline intermediates that were converted into amides via Lewis acid catalysis. Preliminary st
Isomerization of terminal epoxides by a [Pd-H] catalyst: A combined experimental and theoretical mechanistic study
Vyas, Devendra J.,Larionov, Evgeny,Besnard, Celine,Guenee, Laure,Mazet, Clement
supporting information, p. 6177 - 6183 (2013/06/04)
An unusual palladium hydride complex has been shown to be a competent catalyst in the isomerization of a variety of terminal and internal epoxides. The reaction displayed broad scope and synthetic utility. Experimental and theoretical evidence are provided for an unprecedented hydride mechanism characterized by two distinct enantio-determining steps. These results hold promise for the development of an enantioselective variant of the reaction.
β-tert-Butyl aspartate as an organocatalyst for the asymmetric α-amination of α,α-disubstituted aldehydes
Theodorou, Alexis,Papadopoulos, Giorgos N.,Kokotos, Christoforos G.
supporting information, p. 5438 - 5443 (2013/07/05)
The enantioselective α-amination reaction of α,α- disubstituted aldehydes can lead to a variety of enantioenriched amino aldehydes, amino alcohols, and amino acids. After screening a variety of amino acids and their derivatives, we identified a cheap, simple, commercially available aspartic acid derivative that can catalyze efficiently the reaction between α,α-disubstituted aldehydes and dialkyl azodicarboxylates. The reaction proceeds smoothly leading to the corresponding α-aminated adducts in moderate to quantitative yields and moderate to high enantioselectivities (up to 96% ee). Finally, the conversion of these adducts to α,α-disubstituted quaternary amino acids is also described.
AZEPINO [4, 5-B] INDOLES AND METHODS OF USE
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Page/Page column 256, (2010/05/14)
This disclosure relates to new azepino[4,5-b]indole compounds that may be used to modulate a histamine receptor in an individual. Novel compounds are described, including new 1, 2,3,4,5, 6-tetrahydroazepino[4,5-b]indoles. Pharmaceutical compositions are also provided.
PYRIDO (4,3-B) INDOLES CONTAINING RIGID MOIETIES
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Page/Page column 252-253, (2010/05/14)
This disclosure is directed to pyrido[4,3-b]indoles having rigid moieties. The compounds in one embodiment are pyrido[4,3-b]indoles having an unsaturated hydrocarbon moiety. The compounds in another embodiment are pyrido[4,3-b]indoles having a cycloalkyl, cycloalkenyl or heterocyclyl moiety. Pharmaceutical compositions comprising the compounds are also provided, as are methods of using the compounds in a variety of therapeutic applications, including the treatment of a cognitive disorder, psychotic disorder, neurotransmitter-mediated disorder and/or a neuronal disorder.
Efficient catalytic Corey-Chaykovsky reactions involving ketone substrates
Kavanagh, Sarah A.,Piccinini, Alessandro,Connon, Stephen J.
supporting information; experimental part, p. 2089 - 2093 (2010/11/04)
It has been demonstrated for the first time that a sulfide catalyst, utilised at 20 mol% loading, can promote methylene transfer to ketones in the presence of methyl triflate and an organic base. This metal-free methodology is of broad scope-both aliphatic and aromatic ketones (including trifluoromethyl ketones) can be converted to synthetically useful terminal epoxides in excellent yields at room temperature.
Synthesis of quaternary carbon centers via hydroformylation
Sun,Frimpong,Tan
supporting information; experimental part, p. 11841 - 11843 (2010/11/04)
The application of hydroformylation to the synthesis of quaternary carbon centers is reported. The synthesis of the highly substituted carbon is achieved by applying a catalytic amount of 1. Ligand 1 serves as a catalytic directing group by covalently and reversibly binding to both the substrate and catalyst. The intramolecular nature of the directing group strategy accelerates the hydroformylation reaction such that the reaction is performed at mild temperatures (35-55 °C) and with excellent regioselectivity (b:l > 94:6).
