24731-17-7Relevant academic research and scientific papers
Synthesis of γ-Haloesters and γ-Ketoesters by Homolytic Addition of Carbon Radicals Generated by α-Haloesters and Triethylborane to Alkenes and Silyl Enol Ethers
Baciocchi, Enrico,Muraglia, Ester
, p. 2763 - 2766 (1994)
An efficient synthesis of γ-haloesters has been achieved, under very mild conditions, by addition of electrophilic carbon radicals CH(R)CO2Et (R=H, Me, CO2Et) generated by XCH(R)CO2Et (X=Br, I)/BEt3/air in DMSO to alkenes and cycloalkenes.The synthesis of γ-ketoesters is also possible when silyl enol ethers are used as the substrates.
Photocontrolled Cobalt Catalysis for Selective Hydroboration of α,β-Unsaturated Ketones
Beltran, Frédéric,Bergamaschi, Enrico,Funes-Ardoiz, Ignacio,Teskey, Christopher J.
, p. 21176 - 21182 (2020/09/17)
Selectivity between 1,2 and 1,4 addition of a nucleophile to an α,β-unsaturated carbonyl compound has classically been modified by the addition of stoichiometric additives to the substrate or reagent to increase their “hard” or “soft” character. Here, we demonstrate a conceptually distinct approach that instead relies on controlling the coordination sphere of a catalyst with visible light. In this way, we bias the reaction down two divergent pathways, giving contrasting products in the catalytic hydroboration of α,β-unsaturated ketones. This includes direct access to previously elusive cyclic enolborates, via 1,4-selective hydroboration, providing a straightforward and stereoselective route to rare syn-aldol products in one-pot. DFT calculations and mechanistic experiments confirm two different mechanisms are operative, underpinning this unusual photocontrolled selectivity switch.
Photoredox-Catalyzed Isomerization of Highly Substituted Allylic Alcohols by C?H Bond Activation
Guo, Kai,Huang, Jun,Li, Anding,Li, Yuanhe,Yang, Zhen,Zhang, Zhongchao
, p. 11660 - 11668 (2020/05/25)
Photoredox-catalyzed isomerization of γ-carbonyl-substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C?H bond activation. This catalytic redox-neutral process resulted in the synthesis of 1,4-dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ-position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle.
First and Highly Stereoselective Synthesis of Both Enantiomers of Octahydroindole-2-phosphonic Acid (OicP)
Viveros-Ceballos, José Luis,Martínez-Toto, Erick Iván,Eustaquio-Armenta, César,Cativiela, Carlos,Ordó?ez, Mario
, p. 6781 - 6787 (2017/12/07)
We report the first stereoselective synthesis of (2R,3aR,7aR)- and (2S,3aS,7aS)-octahydroindole-2-phosphonic acid 2 (OicP derivatives). The key points are the highly diastereoselective synthesis of cis-fused bicyclic (3aR,7aR)- and (3aS,7aS)-pyrrolidin-2-ones 4 through a dynamic kinetic resolution of racemic γ-keto acid (±)-5 with (R)- and (S)-phenylglycinol via Meyers' bicyclic lactams, and the highly diastereoselective addition of trimethyl phosphite to the N-acyliminium ions 3 obtained from 4.
Biocatalytic access to nonracemic γ-oxo esters: Via stereoselective reduction using ene-reductases
Turrini, Nikolaus G.,Cioc, Rǎzvan C.,Van Der Niet, Daan J. H.,Ruijter, Eelco,Orru, Romano V. A.,Hall, Mélanie,Faber, Kurt
, p. 511 - 518 (2017/08/14)
The asymmetric bioreduction of α,β-unsaturated γ-keto esters using ene-reductases from the Old Yellow Enzyme family proceeds with excellent stereoselectivity and high conversion levels, covering a broad range of acyclic and cyclic derivatives. Various strategies were employed to provide access to both enantiomers, which are versatile precursors of bioactive molecules. The regioselectivity of hydride addition on di-activated alkenes was elucidated by isotopic labeling experiments and showed strong preference for the keto moiety as activating/binding group as opposed to the ester. Finally, chemoenzymatic synthesis of (R)-2-(2-oxocyclohexyl)acetic acid was achieved in high ee on a preparative scale combining enzymatic reduction followed by ester hydrogenolysis.
NOVEL COMPOUNDS
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Page/Page column 52, (2015/12/17)
Disclosed are novel retinoid-related orphan receptor gamma (RORγ) modulators and their use in the treatment of diseases mediated by RORγ.
Electrochemical reduction of 1-bromomethyl-2-oxocycloalkane-1-carboxylates at silver cathodes in dimethylformamide: One-carbon ring-expansion reactions
Wappes, Ethan A.,Mubarak, Mohammad S.,Peters, Dennis G.
, p. G122 - G127 (2015/04/14)
Cyclic voltammetry and controlled-potential (bulk) electrolysis have been employed to investigate the separate electrochemical reductions of methyl 1-bromomethyl-2-oxocyclopentane-1-carboxylate (1) and ethyl 1-bromomethyl-2-oxocyclohexane-1-carboxylate (2) at silver cathodes in dimethylformamide (DMF) containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF4). Oneelectron reductive cleavage of the carbon-bromine bond of each substrate yields a radical intermediate that undergoes a ring-expansion reaction, followed by hydrogen-atom abstraction from the solvent, to afford methyl 3-oxocyclohexane-1-carboxylate (3a) and ethyl 3-oxocycloheptane-1-carboxylate (3b), respectively, in good yield. Each substrate gives rise to three other products: (a) a debrominated analogue of each starting material, (b) a dimeric species formed via radical coupling, and (c) a species possessing an ester group extended by one carbon atom. Electrolyses of 1 and 2 done in the presence of D2O have revealed that carbanion intermediates result in small amounts from two-electron cleavage of carbon-bromine bonds. A mechanistic scheme, involving both radicals and carbanions, is proposed to account for the formation of the various products.
(4, 5, 6, 7-TETRAHYDRO-1-H-INDOL-7-YL) ACETIC ACID DERIVATIVES FOR TREATMENT OF ALZHEIMER'S DISEASE
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Page/Page column 50, (2008/06/13)
Compounds of formula: (I); are disclosed. The compounds are useful in treating or preventing diseases associated with deposition of Aβ in the brain.
Fragmentation of tertiary cyclopropanol compounds catalyzed by vanadyl acetylacetonate
Kirihara, Masayuki,Kakuda, Hiroko,Ichinose, Motohiro,Ochiai, Yuta,Takizawa, Shinobu,Mokuya, Asuka,Okubo, Kumiko,Hatano, Akihiko,Shiro, Motoo
, p. 4831 - 4839 (2007/10/03)
Tertiary cyclopropanol compounds react with a catalytic amount of vanadyl acetylacetonate in the presence of oxygen affording β-hydroxyketones and β-diketones. For 3-substituted-bicyclo[4.1.0]alkanols, peroxides are obtained, as are the β-hydroxyketones. Conversely, 2- ethoxycarbonylcyclopropyl silyl ethers produce ethyl γ-oxocarboxylate derivatives given the same reaction conditions.
Radical cyclization using a thioacetal group for radical generation
Nishida, Atsushi,Kawahara, Norio,Nishida, Mayumi,Yonemitsu, Osamu
, p. 9713 - 9734 (2007/10/03)
The generation and cyclization of several heterocyclic radicals were investigated. The hydrogen abstraction from 1,3-dithiane, 1,3-dithiolane, and 1,3-oxathiane rings by a benzophenone triplet generated the corresponding heterocyclic radicals, which gave the cyclized products by intramolecular addition to α,β-unsaturated esters. Diastereoselective radical cyclization using chiral acetals was also investigated.
