19190-53-5Relevant academic research and scientific papers
Single-Atom-Based Vanadium Oxide Catalysts Supported on Metal-Organic Frameworks: Selective Alcohol Oxidation and Structure-Activity Relationship
Otake, Ken-Ichi,Cui, Yuexing,Buru, Cassandra T.,Li, Zhanyong,Hupp, Joseph T.,Farha, Omar K.
, p. 8652 - 8656 (2018)
We report the syntheses, structures, and oxidation catalytic activities of a single-atom-based vanadium oxide incorporated in two highly crystalline MOFs, Hf-MOF-808 and Zr-NU-1000. These vanadium catalysts were introduced by a postsynthetic metalation, a
Synergistic Peptide and Gold Catalysis: Enantioselective Addition of Branched Aldehydes to Allenamides
Nicholls, Leo D. M.,Wennemers, Helma
supporting information, p. 17559 - 17564 (2021/10/19)
The combination of a peptide catalyst and a gold catalyst is presented for enantioselective addition reactions between branched aldehydes and allenamides. The two catalysts act in concert to provide γ,δ-enamide aldehydes bearing a fully substituted, benzylic stereogenic center – a structural motif common in many natural products and therapeutically active compounds – with good yields and enantioselectivities. The reaction tolerates a variety of alkyl and alkoxy substituted aldehydes and the products can be elaborated into several chiral building blocks bearing either 1,4- or 1,5- functional group relationships. Mechanistic studies showed that the conformational features of the peptide are important for both the catalytic efficiency and stereochemistry, while a balance of acid/base additives is key for ensuring formation of the desired product over undesired side reactions.
Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters to synthesize γ-ketone esters
Lai, Luhao,Li, A-Ni,Zhou, Jiawei,Guo, Yarong,Lin, Li,Chen, Wei,Wang, Rui
supporting information, p. 2185 - 2190 (2017/03/17)
This work concerns the Mg(OMe)2 promoted allylic isomerization of γ-hydroxy-α,β-alkenoic esters with TMEDA as an additive. The isomerization proceeded under mild conditions and afforded γ-keto esters in high yield (up to 96%) within 2 h. Both (Z)- and (E)-γ-hydroxy-α,β-alkenoic esters were tolerated under the reaction conditions. This transformation involves the in situ formation of a dienolate intermediate from the easily accessible γ-hydroxy-α,β-alkenoic ester. The in situ generated dienolate can react with benzaldehyde and undergo a practical, useful tandem allylic isomerization-Aldol reaction to afford more functionalized compounds.
Donor–Acceptor Complex Enables Alkoxyl Radical Generation for Metal-Free C(sp3)–C(sp3) Cleavage and Allylation/Alkenylation
Zhang, Jing,Li, Yang,Xu, Ruoyu,Chen, Yiyun
supporting information, p. 12619 - 12623 (2017/09/11)
The alkoxyl radical is an essential and prevalent reactive intermediate for chemical and biological studies. Here we report the first donor–acceptor complex-enabled alkoxyl radical generation under metal-free reaction conditions induced by visible light. Hantzsch ester forms the key donor–acceptor complex with N-alkoxyl derivatives, which is elucidated by a series of spectrometry and mechanistic experiments. Selective C(sp3)-C(sp3) bond cleavage and allylation/alkenylation is demonstrated for the first time using this photocatalyst-free approach with linear primary, secondary, and tertiary alkoxyl radicals.
Rapid determination of enantiomeric excess of α-chiral aldehydes using circular dichroism spectroscopy
Barman, Sanmitra,Anslyn, Eric V.
, p. 1357 - 1362 (2014/02/14)
A method for enantiodiscrimination of α-chiral aldehydes is reported. The method utilizes circular dichroism (CD) spectroscopy and a sensing ensemble composed of 2-(1-methylhydrazinyl) pyridine (1) and Fe(II)(TfO)2. Aldehydes react rapidly with hydrazine (1) to form chiral imines, which form complexes with Fe(II). By monitoring the CD bands above 320 nm, one can determine the enantiomeric excess (ee) values of α-chiral aldehydes with an average absolute error of ±5%. The analysis was fast, and thus can have potential applications in high-throughput screening (HTS) of catalytic asymmetric induction.
Aniline mediated oxidative C-C bond cleavage of α-alkoxy aldehydes in air and a model reaction for the synthesis of α-(d)-amino acid derivatives
Hu, Bin,Li, Yunfeng,Li, Zhongjun,Meng, Xiangbao
supporting information, p. 4138 - 4141 (2013/07/05)
A metal-free and 4-methyl aniline mediated method for the oxidative C-C bond cleavage has been developed. The reaction proceeds in air using molecular oxygen as the oxidant, affording one-carbon shortened esters in moderate to good yields within a short time. Moreover, it provides a model reaction for the highly enantioselective synthesis of (d)-serine esters by combining with a l-proline catalyzed Mannich reaction.
Oxidative cleavage of α-aryl aldehydes using iodosylbenzene
Havare, Nizam,Plattner, Dietmar A.
supporting information, p. 5078 - 5081,4 (2020/09/15)
We found that α-aryl aldehydes can be cleaved to chain-shortened carbonyl compounds and formaldehyde by various iodosylbenzene complexes. A mechanistic scheme is presented that accounts for the loss of one carbon atom. Formaldehyde is further oxidized to CO and CO2 under the reaction conditions.
Enantiomerically pure α-methoxyaryl acetaldehydes as versatile precursors: a facile chemo-enzymatic methodology for their preparation
Singh, Buddh,Gupta, Pankaj,Chaubey, Asha,Parshad, Rajinder,Sharma, Shiromani,Taneja, Subhash C.
experimental part, p. 2579 - 2588 (2009/04/05)
A facile and efficient synthesis of optically active α-methoxyaryl acetic acids (up to 95% ee), α-methoxyaryl ethanols (up to 93% ee) and α-methoxyaryl acetonitriles (up to 93% ee) was achieved via Arthrobacter sp. lipase-catalyzed kinetic resolution of masked aldehydes as the key synthons, that is, α-hydroxyaryl acetaldehyde acetals.
Synthesis of 3-fluorofuran-2(5H)-ones based on Z/E photoisomerisation and cyclisation of 2-fluoro-4-hydroxybut-2-enoates
Pomeisl, Karel,Cejka, Jan,Kvicala, Jaroslav,Paleta, Oldrich
, p. 5917 - 5925 (2008/04/13)
Mixtures of some (E)- and (Z)-2-fluoroalk-2-enoates prepared from the corresponding 2-hydroxycarbonyl compounds and ethyl 2-(diethoxyphosphoryl)-2- fluoroacetate have been transformed in high conversions into the target 3-fluorofuran-2(5H)-ones by an effi
An alkyne hydrosilylation-oxidation strategy for the selective installation of oxygen functionality
Trost, Barry M.,Ball, Zachary T.,Laemmerhold, Kai M.
, p. 10028 - 10038 (2007/10/03)
Alkynes bearing propargylic, homopropargylic, and bishomopropargylic hydroxyl groups are shown to serve as precursors for ketone or α-hydroxy ketone functionality. The approach hinges on the intermediacy of vinylsilanes created through regioselective hydrosilylation catalyzed by the complex [Cp*Ru(MeCN)3]-PF6. Several oxidative pathways of linear and cyclic vinylsilanes are studied, and the possibility of diastereoselective epoxidation of cyclic vinylsilanes is demonstrated. The sequences constitute the equivalent of stereoselective aldol, homo-aldol, and bishomo-aldol type processes. The method is applied to a short synthesis of the piperidine alkaloid, spectaline.
