96481-55-9Relevant academic research and scientific papers
Ambruticins: tetrahydropyran ring formation and total synthesis
Bowen, James I.,Crump, Matthew P.,Wang, Luoyi,Willis, Christine L.
supporting information, p. 6210 - 6215 (2021/07/28)
The ambruticins are a family of polyketide natural products which exhibit potent antifungal activity. Gene knockout experiments are in accord with the proposal that the tetrahydropyran ring of the ambruticins is formedviathe AmbJ catalysed epoxidation of the unsaturated 3,5-dihydroxy acid, ambruticin J, followed by regioselective cyclisation to ambruticin F. Herein, a convergent approach to the total synthesis of ambruticin J is described as well as model studies involving epoxidation and cyclisations of unsaturated hydroxy esters to give tetrahydropyrans and tetrahydrofurans. The total synthesis involves preparation of three key fragments which were unitedviaa Suzuki-Miyaura cross-coupling and Julia-Kocienski olefination to generate the required carbon framework. Global deprotection to a triol and selective oxidation of the primary alcohol gave, after hydrolysis of the lactone, ambruticin J.
Chromium-Catalyzed Production of Diols From Olefins
-
Paragraph 0111, (2021/03/19)
Processes for converting an olefin reactant into a diol compound are disclosed, and these processes include the steps of contacting the olefin reactant and a supported chromium catalyst comprising chromium in a hexavalent oxidation state to reduce at least a portion of the supported chromium catalyst to form a reduced chromium catalyst, and hydrolyzing the reduced chromium catalyst to form a reaction product comprising the diol compound. While being contacted, the olefin reactant and the supported chromium catalyst can be irradiated with a light beam at a wavelength in the UV-visible spectrum. Optionally, these processes can further comprise a step of calcining at least a portion of the reduced chromium catalyst to regenerate the supported chromium catalyst.
Mechanistic Insight into Palladium-Catalyzed Cycloisomerization: A Combined Experimental and Theoretical Study
Mekareeya, Aroonroj,Walker, P. Ross,Couce-Rios, Almudena,Campbell, Craig D.,Steven, Alan,Paton, Robert S.,Anderson, Edward A.
supporting information, p. 10104 - 10114 (2017/08/03)
The cycloisomerization of enynes catalyzed by Pd(OAc)2 and bis-benzylidene ethylenediamine (bbeda) is a landmark methodology in transition-metal-catalyzed cycloisomerization. However, the mechanistic pathway by which this reaction proceeds has remained unclear for several decades. Here we describe mechanistic investigations into this reaction using enynamides, which deliver azacycles with high regio- and stereocontrol. Extensive 1H NMR spectroscopic studies and isotope effects support a palladium(II) hydride-mediated pathway and reveal crucial roles of bbeda, water, and the precise nature of the Pd(OAc)2 pre-catalyst. Computational studies support these mechanistic findings and lead to a clear picture of the origins of the high stereocontrol that can be achieved in this transformation, as well as suggesting a novel mechanism by which hydrometalation proceeds.
Stereoselective synthesis of conjugated trienols from allylic alcohols and 1-iodo-1,3-dienes
Brandt, Damien,Bellosta, Veronique,Cossy, Janine
supporting information, p. 5594 - 5597,4 (2012/12/12)
The stereoselective synthesis of conjugated trienes has been achieved from allylic alcohols and 1-iodo-1,3-dienes using Pd(OAc)2/AgOAc.
Asymmetric syntheses of 8-oxabicyclo[3,2,1]octanes: A cationic cascade cyclization
Li, Bin,Zhao, Yu-Jun,Lai, Yin-Chang,Loh, Teck-Peng
supporting information; experimental part, p. 8041 - 8045 (2012/09/05)
High octane: A novel and practical syntheses of 8-oxabicyclo[3.2.1]octanes using a cationic cascade cyclization reaction has been developed (see scheme; TIPS=triisopropylsilyl). The diastereomer of the cyclization product isolated depends upon whether the acetal or aldehyde substrate is used. Copyright
Cross-metathesis reactions of homoallyl methyl malonates with sterically hindered allylic esters
Barile, Fabio,Bassetti, Mauro,D'Annibale, Andrea,Gerometta, Renzo,Palazzi, Michele
experimental part, p. 6519 - 6526 (2011/12/05)
The methyl malonate esters of 3-buten-1-ol and 2-methyl-3-buten-1-ol can be coupled efficiently to different methallylic esters in the presence of the second-generation Grubbs catalyst to yield trisubstituted olefins by the cross-metathesis reaction. Product selectivity and yields depend on the relative amounts of reagents and to a minor extent on the methallylic ester functional group. Alkyl substituents at either the allylic or the geminal positions significantly affect the product yields and the E/Z stereoselectivity. The cross-metathesis reactions of homoallyl malonates with allylic esters featuring a variety of alkyl substituents at the vinylic and/or allylic positions afford trisubstituted olefins. Copyright
Copper catalyzed asymmetric synthesis of chiral allylic esters
Geurts, Koen,Fletcher, Stephen P.,Feringa, Ben L.
, p. 15572 - 15573 (2007/10/03)
The complex derived from Taniaphos ligand 4 and CuBr?Me2S catalyzes the asymmetric addition of Grignard reagents to 3-bromopropenyl esters 1 to provide allylic esters 2 in high yields and high chemio-, regio-, and enantioselectivities. The work demonstrates that allylic asymmetric alkylation (AAA) can be done on substrates bearing a heteroatom at the γ-position. The method is a practical route to chiral, nonracemic allylic alcohols. The use of functionalized substrates 1 or Grignard reagents leads to more complex products 2, which can be further manipulated as demonstrated in conversion to (S)-5-ethyl-2(5H)-furanone 6 and (S)-benzoic acid-cyclopent-2-enyl ester 7. Copyright
Confined space-controlled hydroperoxidation of trisubstituted alkenes adsorbed on pentasil zeolites
Chen, Yu-Zhe,Wu, Li-Zhu,Zhang, Li-Ping,Tung, Chen-Ho
, p. 4676 - 4681 (2007/10/03)
Photosensitized oxidation of trialkylalkenes 2-methyl-2-pentene (1), 1-methylcyclohexene (2), trans-3-methyl-2-pentene (3), cis-3-methyl-2-pentene (4), and 2-methyl-2-butene (5) included in the internal framework of Na-ZSM-5 zeolites was investigated. The zeolite samples having adsorbed the alkenes were suspended in isooctane, and the sensitizer, tetraphenylporphyrin (TPP), was dissolved in the solution. Singlet oxygen produced in the solution diffused into the internal framework of the zeolites and reacted with alkenes. For all the substrates studied, the ene-type allylic hydroperoxides were obtained in a highly regioselective manner. The regiochemistry for 1-4 in favor of the allylic hydrogen abstraction from the largest substituents is in contrast to their photooxidation within the dye-supported zeolite Na-Y, where the secondary hydroperoxides are preferentially produced. The tight confinement of the alkenes within the narrow channels of the ZSM-5 zeolites is likely to be responsible for this selectivity.
Liquid-phase isomerization of saturated and unsaturated epoxides
Mel'nik,Khvatova,Moskvichev,Srednev,Egorova
, p. 167 - 169 (2007/10/03)
The liquid-phase isomerization of a variety of epoxides was studied using a complex catalyst system based on magnesium bromide and dimethylformamide. The data obtained elucidate the mechanism of the liquid-phase isomerization and show the range of oxygen-containing compounds which can be prepared through this reaction.
Formal total synthesis of (+)-methynolide
Cossy, Janine,Bauer, David,Bellosta, Véronique
, p. 5909 - 5922 (2007/10/03)
A formal total synthesis of (+)-methynolide was achieved in 23 steps highlighted by a crotylboration, a ring-closing metathesis, a Sharpless kinetic resolution of an allylic alcohol and a Takai reaction.
