5746-69-0Relevant academic research and scientific papers
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.
Synthesis of poly(decahydro-2-naphthyl methacrylate)s with different geometric structures and effects of side-group dynamics on polymer properties investigated by thermal and dynamic mechanical analyses and DFT calculations
Ozaki, Anri,Sumita, Koha,Goto, Kunihiro,Matsumoto, Akikazu
, p. 2941 - 2950 (2013/06/05)
We prepared the geometric isomers of decahydro-2-naphthols as the source materials for the synthesis of poly(decahydro-2-naphthyl methacrylate)s [poly(DNMA)-I, -II, -III, and -IV] including alicyclic ester groups with different geometric structures. The geometry and conformational dynamics of the decahydro-2-naphthyl moieties were investigated by NMR spectroscopy and DFT calculations. We synthesized each isomer of the methacrylic monomers, polymerized them, and investigated the optical, thermal, and mechanical properties of poly(DNMA)s with different isomer compositions. The Tg values of the poly(DNMA)s were in the following order: 139.3 C for poly(DNMA)-II 3/g, 1.489, and 42-44, respectively.
An iron catalyst for oxidation of alkyl C-H bonds showing enhanced selectivity for methylenic sites
Prat, Irene,Gomez, Laura,Canta, Merce,Ribas, Xavi,Costas, Miquel
supporting information, p. 1908 - 1913 (2013/03/14)
Many are called but few are chosen: A nonheme iron complex catalyzes the oxidation of alkyl C-H bonds by using H2O2 as the oxidant, showing an enhanced selectivity for secondary over tertiary C-H bonds (see scheme). Copyright
Oxidative functional group transformations with hydrogen peroxide catalyzed by a divanadium-substituted phosphotungstate
Mizuno, Noritaka,Kamata, Keigo,Yamaguchi, Kazuya
scheme or table, p. 157 - 161 (2012/06/18)
A divanadium-substituted phosphotungstate TBA4[γ-PW 10O38V2(μ-OH)(μ-O)] (I, TBA = tetra-n-butylammonium) reacts with one equivalent H+ to form a bis-μ-hydroxo species [γ-PW10O38V 2(μ-OH)2]3- (I′) in organic media. The strong electrophilic oxidants such as [γ-PW10O 38V2(μ-OH)(μ-OOH)]3- (II) and [γ-PW10O38V2(μ-η2: η2-O2)]3- (III) are formed by the reaction of the bis-μ-hydroxo species with H2O2. In the presence of I and H+, H2O2-based oxidations such as (i) epoxidation of alkenes (17 examples including electron-deficient ones), (ii) hydroxylation of alkanes (11 examples), and (iii) oxidative bromination of alkenes, alkynes, and aromatics with Br- as a bromo source (12 examples including chlorination) chemo-, diastereo-, and regioselectively proceed to give the corresponding oxidized products in moderate to high yields with high efficiencies of H2O2 utilization.
Synthesis and Pseudomonas lipase inhibition study of stereoisomers of decahydro-2-naphthyl-N-n-butylcarbamate
Lin, Ming-Cheng,Shen, Yu-Fang,Lin, Gialih
experimental part, p. 1168 - 1176 (2012/06/15)
(2S,4aR,8aS)-Cis,cis-, (2R,4aS,8aR)-cis,cis-, rac-cis,cis-, and rac-trans,cis-decahydro-2-naphthyl-N-n-butylcarbamates are synthesized from condensation of (2S,4aR,8aS)-cis,cis-, (2R,4aS,8aR)-cis,cis-, rac-cis,cis-, and rac-trans,cisdecahydro-2-naphthols, respectively, with n-butyl isocyanate in the presence of triethylamine in dichloromethane. Optically pure (2S,4aR,8aS)-(-)-and (2R,4aS,8aR)-(+)-cis,cis-decahydro-2-naphthols are resolved by the porcine pancreatic lipase-catalyzed acetylation of decahydro-2-naphthols with vinyl acetate in t-butyl methyl ether. Absolute configurations of (2S,4aR,8aS)-(-)-and (2R,4aS,8aR)-(+)-cis,cis-decahydro-2-naphthols are determined from the 19F NMR spectra of their Mosher's ester derivatives. (2S,4aR,8aR)-Trans,cis-and (2R,4aS,8aS)-trans,cis-decahydro-2- naphthols can't be resolved from the porcine pancreatic lipase-catalyzed acetylation of decahydro-2-naphthols with vinyl acetate in t-butyl methyl ether. For the inhibitory potency of Pseudomonas lipase, (2S,4aR,8aS)-cis,cis- decahydro-2-naphthyl-N-n-butylcarbamate is 3.5 times more potent than (2R,4aS,8aR)-cis,cis-decahydro-2-naphthyl-N-n-butylcarbamate; racemic cis,cis-decahydro-2-naphthyl-N-n-butylcarbamate is about the same with trans,cis-decahydro-2-naphthyl-N-n-butylcarbamate. These inhibitors also show similar effects on porcine pancreatic lipase.
Construction of a quaternary carbon at the carbonyl carbon of the cyclohexane ring
Kaneko, Yuki,Kiyotsuka, Yohei,Acharya, Hukum P.,Kobayashi, Yuichi
supporting information; experimental part, p. 5482 - 5484 (2010/10/04)
High SN2′ selectivity in the allylic substitution of cyclohexylidene ethyl picolinates with copper reagents prepared from RMgBr and CuBr·Me2S was realized by addition of ZnX2 (X = I, Br, Cl). Furthermore, ZnX2 accelerated the reaction with the bulky iPr reagent. The Royal Society of Chemistry 2010.
Efficient stereo- and regioselective hydroxylation of alkanes catalysed by a bulky polyoxometalate
Kamata, Keigo,Yonehara, Kazuhiro,Nakagawa, Yoshinao,Uehara, Kazuhiro,Mizuno, Noritaka
scheme or table, p. 478 - 483 (2010/09/17)
Direct functionalization of alkanes by oxidation of C-H bonds to form alcohols under mild conditions is a challenge for synthetic chemistry. Most alkanes contain a large number of C-H bonds that present difficulties for selectivity, and the oxidants employed often result in overoxidation. Here we describe a divanadium-substituted phosphotungstate that catalyses the stereo- and regioselective hydroxylation of alkanes with hydrogen peroxide as the sole oxidant. Both cyclic and acyclic alkanes were oxidized to form alcohols with greater than 96% selectivity. The bulky polyoxometalate framework of the catalyst results in an unusual selectivity that can lead to the oxidation of secondary rather than the weaker tertiary C-H bonds. The catalyst also avoids wasteful decomposition of the stoichiometric oxidant, which can result in the production of hydroxyl radicals and lead to non-selective oxidation and overoxidation of the desired products.
Rhodium/graphite-catalyzed hydrogenation of carbocyclic and heterocyclic aromatic compounds
Falini, Giuseppe,Gualandi, Andrea,Savoia, Diego
experimental part, p. 2440 - 2446 (2010/02/27)
Rhodium on graphite (Rh/Gr, C24Rh) was prepared by reaction of anhydrous rhodium trichloride with potassium graphite (C8K, 3 equivalents) and used as a heterogeneous catalyst for the hydrogenation of carbocyclic and heterocyclic aromatic compounds at room temperature and 1 atm of hydrogen pressure. The effect of substitution on the benzene ring was examined in a variety of derivatives, including those with alkyl, hydroxy, alkoxy, aryloxy, carboxy, amino, nitro, acyl, chloro, or functionalized alkyl groups. Reduction of carbonyl functions of aromatic aldehydes and ketones occurred with complete or partial cleavage of the benzylic C-O bond; this cleavage also occurred in the hydrogenation of benzylic alcohols and esters. Georg Thieme Verlag Stuttgart.
Functional-Group-Directed Diastereoselective Hydrogenation of Aromatic Compounds
Ranade, Vidyadhar S.,Consiglio, Giambattista,Prins, Roel
, p. 8862 - 8867 (2007/10/03)
Diastereoselective liquid phase hydrogenation of a series of monosubstituted indane and tetralin substrates was studied on supported rhodium catalysts. Predominantly the cis-cis diastereomer, obtained by hydrogenation from the diastereoface opposite the substituent (at the stereogenic center), and the cis-trans diastereomer, obtained by hydrogenation from the diastereoface on the same side as the substituent, were formed. The diastereoselectivity between the two isomers was dependent on the steric repulsion or the electronic attraction of the substituent with the surface of the catalyst. The hydroxyl group did not exhibit a strong attraction (haptophilicity), and the cis-cis diastereomer was obtained as the major product. The amino group exhibited a very high haptophilicity, yielding primarily the cis-trans diastereomer. The diastereoselectivity obtained in the hydrogenation of all the substrates was influenced on addition of bases to the reaction mixture. In the case of alcoholic substrates, the selectivity to the cis-trans diastereomer could be substantially increased with alkaline hydroxide additives.
Role of the heteroatoms in the complex metal hydride reduction of 2-t- butyl-1,3-dioxan-5-one and 3-oxoquinolizidine: Comparison of their reactivity and stereochemistry with those of the corresponding carbocyclic compounds
Senda, Yasuhisa,Sakurai, Hiroshi,Itoh, Hiroki
, p. 285 - 288 (2007/10/03)
The complex metal hydride reductions of 2-t-butyl-1,3-dioxan-5-one (1) and 3-oxoquinolizidine (3) are faster than those of the corresponding carbocyclic compounds, 4-t-butylcyclohexanone (2) and trans-2-decalone (4). The stereoselectivities were similar in the LiAlH4 reduction, but the heteracyclohexanones exhibited higher stereoselectivity with NaBH4. These facts are discussed in terms of the intramolecular orbital interaction.
