24124-06-9Relevant academic research and scientific papers
Fe(III)-Catalyzed Diastereoselective Friedel-Crafts Alkylation-Hemiketalization-Lactonization Cascade for the Synthesis of Polycyclic Bridged 2-Chromanol Lactones
Borade, Balasaheb R.,Nomula, Rajesh,Gonnade, Rajesh G.,Kontham, Ravindar
supporting information, p. 2629 - 2633 (2019/04/17)
An unprecedented Fe(III)-catalyzed Friedel-Crafts alkylation-hemiketalization-lactonization cascade of electron-rich hydroxy arenes and distinctively functionalized unsaturated 4-keto esters is developed for the construction of polycyclic bridged 2-chroma
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
supporting information, 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.
From vinyl pyranoses to carbasugars by an iron-catalyzed reaction complementary to classical Ferrier carbocyclization
Mac, Dinh Hung,Samineni, Ramesh,Petrignet, Julien,Srihari, Pabbaraja,Chandrasekhar, Srivari,Yadav, Jhillu Singh,Gree, Rene
supporting information; experimental part, p. 4717 - 4719 (2010/01/16)
Starting from vinyl pyranoses an iron-catalyzed tandem isomerization- intramolecular aldolization reaction was developed to prepare cyclohexenone derivatives bearing substituents on the double bond, and it has been applied in a short synthesis of 4-epi-ga
Microwave-assisted regioselective olefinations of cyclic mono- and di-ketones with a stabilized phosphorus ylide
Wu, Jinlong,Li, Dan,Wu, Huafeng,Sun, Lijie,Dai, Wei-Min
, p. 4643 - 4650 (2007/10/03)
A number of cyclic mono- and di-ketones underwent regioselective olefination with (carbethoxyethylidene)triphenylphospharane under controlled microwave heating. The Wittig reaction of 4-substituted cyclohexanones or 1,2- and 1,4-cyclohexanediones with the ylide at 190 °C for 20 min in MeCN afforded the exocyclic olefins in >94:6 isomer ratios. On the other hand, the same reactions carried out at 230 °C for 20 min in the presence of 20 mol % DBU furnished the endocyclic olefins in >83:17 isomer ratios. The base-mediated isomerization of the exocyclic olefins into the endocyclic isomers was primarily driven by thermodynamic stability of the products and the effect of ring structures on deconjugation was examined.
Divergent enantioselective synthesis of (-)-galanthamine and (-)-morphine
Trost, Barry M.,Tang, Weiping,Toste, F. Dean
, p. 14785 - 14803 (2007/10/03)
An efficient divergent synthetic strategy for the synthesis of the opiate and amaryllidaceae alkaloids emerges by employing a Pd-catalyzed asymmetric allylic alkylation (AAA) to set the stereochemistry. Three generations of syntheses of galanthamine are discussed in detail with particular focus on the scope of the palladium-catalyzed AAA reactions and intramolecular Heck reactions. The pivotal tricyclic intermediate is available in six steps from 2-bromovanillin and the monoester of methyl 6-hydroxycyclohexene-1-carboxylate. This intermediate requires only two steps to convert to (-)-galanthamine. Using a Heck vinylation, we found that the fourth ring of codeine/morphine could be formed. The final ring formation involves a novel visible light-promoted hydroamination. Thus, six steps are required to convert the pivotal tricyclic intermediate into codeine, which has been demethylated in high yield to morphine.
SYNTHESES DE CYCLOHEXENONES α-SUBSTITUEES VIA LA THERMOLYSE DE CETOSULFOXYDES TERTIAIRES
Barillier, Daniel,Benhida, Rachid,Vazeux, Michel
, p. 83 - 96 (2007/10/02)
The sulfenylation-dehydrosulfenylation method, combined with carbon-carbon bond forming reactions, has been applied to the synthesis of some α-functionalized cyclohexenones 3.Hence, the sodium anion of the 2-methylthiocyclohexanone in THF reacts with primary, allyl and benzyl halides as well as with Michael acceptors to lead to the tertiary ketosulfides 1a-j.Further oxidation by NaIO4 and thermolysis in boiling toluene of the resulting sulfoxides 2 have been performed.The scope and limitations of this strategy are also discussed. Key Words: α-functionalized cyclohexenones; tertiary ketosulfides and ketosulfoxides; sulfenylation and deshydrosulfenylation; thermolysis.
Tandem Cope-Claisen Rearrangement: Scope and Stereochemistry
Ziegler, Frederick E.,Piwinski, John J.
, p. 7181 - 7190 (2007/10/02)
The complete details of the seminal study on the tandem Cope-Claisen rearrangement are presented.The reaction uses an initial Cope rearrangement to trigger an irreversible Claisen rearrangement.In several cases, the Claisen step drives an unfavorable Cope
