1579-21-1Relevant academic research and scientific papers
Equilibration of Alkene Regioisomers in trans- and cis-Octalins
Thompson, Hugh W.,Gaglani, Kamlesh D.
, p. 967 - 972 (1993)
As models for studying the energetics of double-bond regiochemistry in the octalin system, the enol acetates of trans- and cis-2-decalone (1,4), trans- and cis-10-methyl-2-decalone (7,10) and trans- and cis-9-methyl-2-decalone (13,16) have been synthesized.Acid-catalyzed equilibrations of double-bond position were conducted in acetic anhydride at ca. 60, 100 and 140 deg C and assessed by integration of the vinyl-proton NMR signals, which were unambiguously assigned to each enol acetate either by the observed splitting pattern or synthesis.Values of ΔH and ΔS (Δ2:Δ1) are derived and compared with experimental and theoretical literature values.Values of ΔH for the enol acetates of 1 and 4 are -0.69 and 0.0 kcal mol-1, respectively, and addition of an angular methyl decreases the relative stability (ΔH) of the Δ1 isomer, by 1.25 - 2.25 kcal mol-1 for the trans skeleton and by 1.0 - 1.4 kcal mol-1 for the cis skeleton.For a given angular substituent, changing cis stereochemistry to trans also decreases the relative Δ1-stability, by 0.7 kcal mol-1 when R = H and 0.95 - 1.55 kcal mol-1 when R = Me.Values of ΔS are all small, between +0.1 and -3.2 cal mol-1 K-1.Trends in the data and features of the 1H NMR spectra related to conformation are discussed, and an approach is suggested for calculating approximate ΔH, ΔS and ΔG values for Δ1-9-methyl- vs. Δ1-10-methyloctalin in the trans and cis series.
High trans-2-Decalones by Photoredox Catalyzed β-Isomerization
Barnes, Quentin,Biremond, Tony,Quintaine, Julie,Saudan, Lionel,Sombret, Juliette,de Saint-Laumer, Jean-Yves
, (2021/12/03)
The synergistic combination of three catalytic processes – photoredox, enamine and hydrogen atom transfer (HAT) catalysis – enabled the β-isomerization of 2-decalones towards the thermodynamically most stable trans-isomers. A library of iridium (III) complexes and organic dyes were screened in combination with cyclic amines and thiols which after optimization gave the desired trans-2-decalones with high trans/cis ratios of 60 : 40 up to 98 : 2.
Ozonation of decalin as a model saturated cyclic molecule: A spectroscopic study
Bykov, Gennadii L.,Ershov, Boris G.,Krasovskiy, Vladimir G.,Kustov, Alexander L.,Kustov, Leonid M.,Panich, Nadezhda M.
, (2021/09/20)
Ozonolysis is used for oxidation of a model cyclic molecule-decalin, which may be consid-ered as an analog of saturated cyclic molecules present in heavy oil. The conversion of decalin exceeds 50% with the highest yield of formation of acids about 15–17%. Carboxylic acids, ketones/aldehydes, and alcohols are produced as intermediate products. The methods of UV-visible, transmission IR, at-tenuated total reflection IR-spectroscopy, NMR and mass-spectrometry were used to identify reaction products and unravel a possible reaction mechanism. The key stage of the process is undoubtedly the activation of the first C-H bond and the formation of peroxide radicals.
Enhancing Chemo- And Stereoselectivity in C-H Bond Oxygenation with H2O2by Nonheme High-Spin Iron Catalysts- And Role of Lewis Acid and Multimetal Centers
Das, Abhishek,Jana, Rahul Dev,Paine, Tapan Kanti
, p. 5969 - 5979 (2021/05/04)
Spin states of iron often direct the selectivity in oxidation catalysis by iron complexes using hydrogen peroxide (H2O2) on an oxidant. While low-spin iron(III) hydroperoxides display stereoselective C-H bond hydroxylation, the reactions are nonstereoselective with high-spin iron(II) catalysts. The catalytic studies with a series of high-spin iron(II) complexes of N4 ligands with H2O2 and Sc3+ reported here reveal that the Lewis acid promotes catalytic C-H bond hydroxylation with high chemo- and stereoselectivity. This reactivity pattern is observed with iron(II) complexes containing two cis-labile sites. The enhanced selectivity for C-H bond hydroxylation catalyzed by the high-spin iron(II) complexes in the presence of Sc3+ parallels that of the low-spin iron catalysts. Furthermore, the introduction of multimetal centers enhances the activity and selectivity of the iron catalyst. The study provides insights into the development of peroxide-dependent bioinspired catalysts for the selective oxygenation of C-H bonds without the restriction of using iron complexes of strong-field ligands.
ISOMERISATION REACTION
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Paragraph 16, (2020/10/09)
The present invention relates to the field of organic synthesis and more specifically to the isomerization of the β position of a β?trisubstituted C3-C70 carbonyl compound.
The debut of chiral cyclic (alkyl)(amino)carbenes (CAACs) in enantioselective catalysis
Pichon, Delphine,Soleilhavoup, Michele,Morvan, Jennifer,Junor, Glen P.,Vives, Thomas,Crévisy, Christophe,Lavallo, Vincent,Campagne, Jean-Marc,Mauduit, Marc,Jazzar, Rodolphe,Bertrand, Guy
, p. 7807 - 7811 (2019/08/30)
The popularity of NHCs in transition metal catalysis has prompted the development of chiral versions as electron-rich neutral stereodirecting ancillary ligands for enantioselective transformations. Herein we demonstrate that cyclic (alkyl)(amino)carbene (CAAC) ligands can also engage in asymmetric transformations, thereby expanding the toolbox of available chiral carbenes.
Alkane oxidation catalysed by a self-folded multi-iron complex
Mettry, Magi,Moehlig, Melissa Padilla,Gill, Adam D.,Hooley, Richard J.
, p. 120 - 128 (2016/11/09)
A preorganised ligand scaffold is capable of coordinating multiple Fe(II) centres to form an electrophilic CH oxidation catalyst. This catalyst oxidises unactivated hydrocarbons including simple, linear alkanes under mild conditions in good yields with selectivity for the oxidation of secondary CH bonds. Control complexes containing a single metal centre are incapable of oxidising unstrained linear hydrocarbons, indicating that participation of multiple centres aids the CH oxidation of challenging substrates.
Iron Complex Catalyzed Selective C-H Bond Oxidation with Broad Substrate Scope
Jana, Sandipan,Ghosh, Munmun,Ambule, Mayur,Sen Gupta, Sayam
supporting information, p. 746 - 749 (2017/03/01)
The use of a peroxidase-mimicking Fe complex has been reported on the basis of the biuret-modified TAML macrocyclic ligand framework (Fe-bTAML) as a catalyst to perform selective oxidation of unactivated 3° C-H bonds and activated 2° C-H bonds with low catalyst loading (1 mol %) and high product yield (excellent mass balance) under near-neutral conditions and broad substrate scope (18 substrates which includes arenes, heteroaromatics, and polar functional groups). Aliphatic C-H oxidation of 3° and 2° sites of complex substrates was achieved with predictable selectivity using steric, electronic, and stereoelectronic rules that govern site selectivity, which included oxidation of (+)-artemisinin to (+)-10β-hydroxyartemisinin. Mechanistic studies indicate FeV(O) to be the active oxidant during these reactions.
From DNA to catalysis: A thymine-acetate ligated non-heme iron(III) catalyst for oxidative activation of aliphatic C-H bonds
Al-Hunaiti, Afnan,R?is?nen, Minn?,Repo, Timo
, p. 2043 - 2046 (2016/02/05)
A non-heme, iron(iii)/THA(thymine-1-acetate) catalyst together with H2O2 as an oxidant is efficient in oxidative C-H activation of alkanes. Although having a higher preference for tertiary C-H bonds, the catalyst also oxidizes aliphatic secondary C-H bonds into carbonyl compounds with good to excellent conversions. Based on the site selectivity of the catalyst and our mechanistic studies the reaction proceeds via an Fe-oxo species without long lived carbon centered radicals.
Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
supporting information, p. 9250 - 9253 (2015/08/11)
Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
