- A density functional, infrared linear dichroism, and normal coordinate study of phenol and its deuterated derivatives: Revised interpretation of the vibrational spectra
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The assignment of the vibrational spectra of phenol has been reexamined on the basis of Raman and new IR measurements and theoretical analysis of the normal modes of vibrations in the electronic ground state. The infrared spectra of C6H5OH, C6D5OD, and C6D5OH have been studied in solution and vapor phases, as well as has the Raman spectra in solutions. New experimental data were obtained from infrared linear dichroism (IR-LD) studies of phenol aligned in uniaxially oriented nematic liquid crystal solution. The measured dichroic ratios and orientation factors indicate an effective Cs symmetry of the molecule with coplanar orientation of OH bond with the benzene ring and supply unique information on the extent of symmetry lowering of benzene normal modes. The fundamental vibrational frequencies, force constants, and dipole derivatives have been calculated by ab initio quantum chemical methods applying the B3P86 density functional approximation with 6-311G** basis set. The force field optimized by means of a least-squares scaling procedure for phenol-d0 (using six scale factors) was used to calculate the frequencies (with a mean deviation from the observed values less than 1%), normal modes, potential energy distributions, transition moment vectors, and IR intensities for phenol-d0, -d1, -d5, and -d6 isotopomers. Compared to the deviations between the calculated and observed absorption intensities, a more satisfactory correlation was found between the calculated and experimentally determined vibrational transition moment directions. The results indicate unanimously that the perturbation of the normal modes of benzene by the asymmetric hydroxyl substituent is so great that the previous practice of assigning the normal vibrations of phenol to those of benzene or even to C2v symmetry species is not justified.
- Keresztury, Gabor,Billes, Ferenc,Kubinyi, Miklos,Sundius, Tom
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Read Online
- Acid p Ka Dependence in O-O Bond Heterolysis of a Nonheme FeIII-OOH Intermediate to Form a Potent FeVa? O Oxidant with Heme Compound I-Like Reactivity
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Protons play essential roles in natural systems in controlling O-O bond cleavage of peroxoiron(III) species to give rise to the high-valent iron oxidants that carry out the desired transformations. Herein, we report kinetic and mechanistic evidence that acids can control the mode of O-O bond cleavage for a nonheme S = 1/2 FeIII-OOH species [(BnTPEN)FeIII(OOH)]2+ (2, BnTPEN = N-benzyl-N,N′,N′-tris(2-pyridylmethyl)-1,2-diaminoethane). Addition of acids having pKa values of >8.5 in CH3CN results in O-O bond homolysis, leading to the formation of hydroxyl radicals that give rise to alcohol/ketone (A/K) ratios of around 1 in the oxidation of cyclohexane. However, the introduction of acids with pKa values of III-OOH intermediate at -40 °C. These results implicate the generation of a highly reactive FeV? O species via proton-assisted O-O bond heterolysis of the FeIII-OOH intermediate, which is unprecedented for nonheme iron complexes supported by neutral pentadentate ligands and serves as a nonheme analogue for heme enzyme compounds I.
- Xu, Shuangning,Draksharapu, Apparao,Rasheed, Waqas,Que, Lawrence
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Read Online
- Aerobic C?C Bond Cleavage Catalyzed by Whole-Cell Cultures of the White-Rot Fungus Dichomitus albidofuscus
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Whole-cell cultures of the basidiomycetous white-rot fungus Dichomitus albidofuscus exhibit varying catalytic activity towards aromatic compounds depending on the growth stage. This study reveals the catalytic behavior of mature whole-cell cultures that effectively catalyze a C?C bond cleavage oxidizing toluene, benzaldehyde and acetophenone to phenol. The reaction products were analyzed by GC-MS and NMR techniques. To exclude the de novo formation of phenol by the fungus, its origin has been proven by bioconversion of benzaldehyde-d5. The key step involves an aerobic Baeyer-Villiger type rearrangement where the incorporation of oxygen into the product was confirmed based on isotope labelling experiments with 18O2. Intermediate esters were not found in reaction mixture presumably due to the detected esterase activity in the mycelium as well as in supernatant of the whole-cell cultures. As a result, the sequence of biocatalytic reactions catalyzed by D. albidofuscus for the degradation of toluene via C?C bond cleavage has been disclosed.
- Zhuk, Tatyana S.,Babkina, Valeriia V.,Zorn, Holger
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- Efficient continuous-flow HD exchange reaction of aromatic nuclei in D2O/2-PrOH mixed solvent in a catalyst cartridge packed with platinum on carbon beads
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Herein, a continuous-flow deuteration methodology for various aromatic compounds is developed based on heterogeneous platinum-catalyzed hydrogen-deuterium exchange. The reaction entails the transfer of a substrate dissolved in a mixed solvent of 2-propanol and deuterium oxide into a catalyst cartridge packed with platinum on carbon beads (Pt/CB). Pt/ CB could be continuously used without significant deterioration of catalyst activity for at least 24 h. Deuteration proceeded within 60 s of the substrate solutions being passed through the Pt/CB layer in the Pt/CB-packed cartridge.
- Park, Kwihwan,Ito, Naoya,Yamada, Tsuyoshi,Sajiki, Hironao
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supporting information
p. 600 - 605
(2021/03/29)
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- Entry to 1,2,3,4-Tetrasubstituted Arenes through Addressing the " Meta Constraint" in the Palladium/Norbornene Catalysis
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Arenes with four different contiguous substituents, i.e. 1,2,3,4-tetrasubstituted arenes, are commonly found in bioactive compounds, but they are nontrivial to access via conventional methods. Through addressing the "meta constraint" in the palladium/norbornene (Pd/NBE) cooperative catalysis, which is the difficulty of tolerating a sizable meta substituent in aryl halide substrates, here a modular and regioselective approach is realized for preparing 1,2,3,4-tetrasubstituted arenes. One key is the use of a C2-amide-substituted NBE, and a combined experimental and computational study reveals its role in promoting the NBE insertion and the ortho C-H metalation steps. The scope is broad: A variety of electrophiles and nucleophiles could be introduced to the ortho and ipso positions, respectively, with 1,4-disubstituted aryl halides, leading to diverse unsymmetrical contiguous tetrasubstituted arenes. Application of this approach has been demonstrated in streamlined syntheses of several bioactive compounds.
- Dong, Guangbin,Liu, Peng,Wang, Jianchun,Xu, Xiaolong,Zhou, Yun
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supporting information
p. 3050 - 3059
(2020/03/10)
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- Single-step benzene hydroxylation by cobalt(ii) catalysts: Via a cobalt(iii)-hydroperoxo intermediate
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The cobalt(ii) complexes of 4N tetradentate ligands have been synthesized and characterized as the catalysts for phenol synthesis in a single step. The molecular structure of the complexes showed a geometry in between square pyramidal and trigonal bipyramidal (τ, 0.49-0.88) with Co-Namine and Co-NPy bond distances of 2.104-2.254 ? and 2.043-2.099 ?, respectively. The complexes exhibited a Co2+/Co3+ redox potential around 0.489-0.500 V vs. Ag/Ag+ in acetonitrile. The complexes catalyzed hydroxylation of benzene using H2O2 (30%) and afforded phenol selectively as the major product. A maximum yield of phenol up to 29% and turnover number (TON) of 286 at 60 °C, and a yield of 19% and TON of 191 at 25 °C are achieved. This is the highest catalytic performance reported using cobalt(ii) complexes as catalysts to date. This aromatic hydroxylation presumably proceeded via a cobalt(iii)-hydroperoxo species, which was characterized by ESI-MS, and vibrational and electronic spectral methods. The formation of key intermediate [(L)CoIII(OOH)]2+ was accompanied by the appearance of the characteristic O → Co(iii) ligand to metal charge transfer (LMCT) transition around 488-686 nm and vibration modes at 832 cm-1 (O-OH) and 564 cm-1 (Co-O). The geometry of one of the catalytically active intermediates was optimized by DFT and its spectral properties were calculated by TD-DFT calculations. These data are comparable to the experimental observations. The kinetic isotope effect (KIE) values (0.98-1.07) support the involvement of cobalt-bound oxygen species as a key intermediate. Isotope-labeling experiments using H218O2 showed an 89% incorporation of 18O, revealing that H2O2 is the main oxygen supplier for phenol formation from benzene. The catalytic efficiencies of cobalt complexes are tuned by ligand architectures via their geometrical configurations and steric properties.
- Anandababu, Karunanithi,Mayilmurugan, Ramasamy,Muthuramalingam, Sethuraman,Velusamy, Marappan
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p. 2540 - 2548
(2020/05/14)
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- Cu(i) complexes obtained: Via spontaneous reduction of Cu(ii) complexes supported by designed bidentate ligands: Bioinspired Cu(i) based catalysts for aromatic hydroxylation
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Copper(i) complexes [Cu(L1-7)2](ClO4) (1-7) of bidentate ligands (L1-L7) have been synthesized via spontaneous reduction and characterized as catalysts for aromatic C-H activation using H2O2 as the oxidant. The single crystal X-ray structure of 1 exhibited a distorted tetrahedral geometry. All the copper(i) complexes catalyzed direct hydroxylation of benzene to form phenol with good selectivity up to 98%. The determined kinetic isotope effect (KIE) values, 1.69-1.71, support the involvement of a radical type mechanism. The isotope-labeling experiments using H218O2 showed 92% incorporation of 18O into phenol and confirm that H2O2 is the key oxygen supplier. Overall, the catalytic efficiencies of the complexes are strongly influenced by the electronic and steric factor of the ligand, which is fine-tuned by the ligand architecture. The benzene hydroxylation reaction possibly proceeded via a radical mechanism, which was confirmed by the addition of radical scavengers (TEMPO) to the catalytic reaction that showed a reduction in phenol formation. This journal is
- Kumari, Sheela,Muthuramalingam, Sethuraman,Dhara, Ashish Kumar,Singh,Mayilmurugan, Ramasamy,Ghosh, Kaushik
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supporting information
p. 13829 - 13839
(2020/10/26)
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- H-D Exchange Deuteration of Arenes at Room Temperature
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Arene nuclei efficiently underwent the hydrogen (H)-deuterium (D) exchange reaction catalyzed by platinum group metals on carbon in a mixed solvent of 2-propanol and D2O at room temperature to produce deuterium-labeled arenes. Platinum on carbon (Pt/C) and iridium on carbon (Ir/C) were applicable catalysts, and the various arenes bearing a carbonyl group, fluorine, phenolic hydroxy group, amino group, or phosphonic acid on the aromatic nucleus were effectively deuterated. Nonheating conditions are valuable for the scalable industrial preparation.
- Sawama, Yoshinari,Nakano, Akihiro,Matsuda, Takumi,Kawajiri, Takahiro,Yamada, Tsuyoshi,Sajiki, Hironao
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supporting information
p. 648 - 653
(2019/02/14)
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- Synthesis and biological evaluation of deuterated sofosbuvir analogs as HCV NS5B inhibitors with enhanced pharmacokinetic properties
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A series of deuterated sofosbuvir analogs were designed and prepared with the aim of improving their pharmacokinetic properties. The devised synthetic routes allow for site-selective deuterium incorporation with high levels of isotopic purity. As expected, the deuterated analogs (37-44) are as efficacious as sofosbuvir when tested in vitro inhibition of viral replication (replicon) assays. Compared with sofosbuvir, deuterated analog 40 displays improved in vivo pharmacokinetics profiles in rats and dogs in terms of the metabolite and the prodrug. The Cmax and area under the curve (AUC) of 40 in dogs were increased by 3.4- and 2.7-fold, respectively. Due to the enhanced pharmacokinetic properties and the great synthetic advantage of an inexpensive deuterium source (D2O) for 40, it was chosen for further investigation.
- Ao, Wangwei,Ma, Xueqin,Lin, Youping,Wang, Xiaojing,Song, Wei,Wang, Qinglin,Zhang, Xiquan,Xu, Hongjiang,Zhang, Yinsheng
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p. 215 - 229
(2019/05/07)
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- Deuterated nucleoside derivative
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The present invention relates to deuterated nucleoside derivative, particularly to a compound having a structure represented by a formula I or a pharmaceutically acceptable salt thereof. According to the present invention, the compound represented by the formula I has excellent pharmacokinetic properties and is expected to reduce the clinical dose so as to reduce the treatment and benefit more patients. The formula I is defined in the specification.
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Paragraph 0077; 0078-0082
(2016/10/07)
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- A substituted heteroaryl compounds and compositions containing such compounds and use thereof (by machine translation)
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The present invention provides a substituted heteroaryl compounds and compositions containing such compounds and its use, the invention discloses a formula (I) indicated by the heteroaryl compound, or its crystalline form, a pharmaceutically acceptable salt, prodrug, stereoisomer, hydrate or compound solvent. The invention of monocyclic the base states compounds and compositions containing such compounds may be used to modulate hypoxia inducible factor (HIF) and/or endogenous erythropoietin (EPO), but also has good pharmacokinetic parameter characteristic, can improve the compound in animal drug concentration, in order to improve the effect of drugs and safety. (by machine translation)
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Paragraph 0108; 0109-0110
(2017/04/19)
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- Ortho-and para-selective ruthenium-catalyzed C(sp2)-H oxygenations of phenol derivatives
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Versatile ruthenium catalysts allowed for efficient direct oxygenations of aryl carbamates under remarkably mild reaction conditions. In addition to chelation-assisted C-H activation, the optimized ruthenium catalyst proved amenable to para-selective hydroxylations of anisoles without Lewis basic directing groups.
- Liu, Weiping,Ackermann, Lutz
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supporting information
p. 3484 - 3486
(2013/07/26)
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- Platinum on carbon-catalyzed H-D exchange reaction of aromatic nuclei due to isopropyl alcohol-mediated self- activation of platinum metal in deuterium oxide
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An efficient and simple deuteration method of arenes using the platinum on carbon-isopropyl alcohol-cyclohexane-deuterium oxide combination under hydrogen gas-free conditions was accomplished. Since the hydrogen-deuterium exchange reaction cannot be promoted without isopropyl alcohol, zerovalent platinum metal (on carbon) is self-activated by the in situ-generated very low amount of hydrogen or hydrogen-deuterium gas derived from isopropyl alcohol or isopropyl alcohol-d1. Deuterium-labeled compounds with high deuterium contents can be easily isolated by the filtration of platinum on carbon and simple extraction. The present hydrogen gas-free method is safe from the viewpoint of process chemistry and various arenes possessing a variety of reducible functionalities within the molecule could be effectively and directly deuterium-labeled without undesired reduction. Copyright
- Sawama, Yoshinari,Yamada, Tsuyoshi,Yabe, Yuki,Morita, Kosuke,Shibata, Kyoshiro,Shigetsura, Masahiro,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 1529 - 1534
(2013/06/27)
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- Photoactivation of (p-methoxyphenyl)(trifluoromethyl)diazirine in the presence of phenolic reaction partners
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Shine light on your chemistry! Irradiating 3-(4-methoxyphenyl)-3- (trifluoromethyl)-3H-diazirine in the presence of equimolar solutions of phenol and tyrosine derivatives leads to Friedel-Crafts alkylations (see scheme), which suggests a strategy for the development of "cleaner" diazirines for chemical biology. Copyright
- Raimer, Bj?rn,Lindel, Thomas
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supporting information
p. 6551 - 6555
(2013/06/27)
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- Catalytic arene H/D exchange with novel rhodium and iridium complexes
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Three novel pendant acetate complexes, [Rh(bdmpza)Cl3] -M+, [Rh(bdmpza)Cl2(py)], and [Ir(bdmpza)Cl3]-M+ (bdmpza = bis(3,5-dimethylpyrazol-1-yl) acetate, M+ = Li+, Na +), were synthesized. Abstraction of halide from these complexes with silver salts yielded species capable of C-H activation of arenes. The catalytic H/D exchange reaction between benzene and trifluoroacetic acid-d was optimized, and these conditions were used to evaluate H/D exchange in other arenes. Branched alkyl substituents in alkyl aromatics showed an affinity toward deuterium exchange in the β-alkyl position only. DFT calculations were performed to determine the mechanism of H/D exchange.
- Rhinehart, Jennifer L.,Manbeck, Kimberly A.,Buzak, Sara K.,Lippa, Geoffrey M.,Brennessel, William W.,Goldberg, Karen I.,Jones, William D.
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experimental part
p. 1943 - 1952
(2012/04/23)
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- Efficient and selective Pt/C-catalyzed H-D exchange reaction of aromatic rings
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An effective and applicable deuteration method for aromatic rings using Pt/C-D2O-H2 system was established. Especially, phenol was fully deuterated even at room temperature, and other electron-rich aromatic nuclei were efficiently deuterated under mild conditions. The scope and limitations of the presence method and its application to the synthesis of deuterium-labeled biologically active compounds and deuterium-labeled building blocks for practical multi-gram scale syntheses are reported. 2008 The Chemical Society of Japan.
- Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Imamiya, Eikoh,Maegawa, Tomohiro,Sajiki, Hironao
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experimental part
p. 278 - 286
(2009/03/12)
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- Aromatic ring favorable and efficient H-D exchange reaction catalyzed by Pt/C
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An effective and applicable Pt/C-catalyzed deuteration method of aromatic rings using D2O as a deuterium source under hydrogen atmosphere was developed. Five percent Pt/C would lead to quite effective H-D exchange results on the aromatic ring systems. The reaction is general for a variety of aromatic compounds including biologically active compounds.
- Sajiki, Hironao,Ito, Nobuhiro,Esaki, Hiroyoshi,Maesawa, Tsuneaki,Maegawa, Tomohiro,Hirota, Kosaku
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p. 6995 - 6998
(2007/10/03)
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- METHOD FOR PRODUCING AROMATIC HYDROCARBON
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PROBLEM TO BE SOLVED: To provide a method for producing an aromatic compound having deutrium, excellent in an economical property and an all purpose property. SOLUTION: This method for producing the aromatic compound is characterized by producing a compound having deutrium at at least one of selected positions among ortho-, meta- and para-positions by performing a substitution reactions on hydrogen directly bonded to a benzene ring of a compound expressed by formula (1) [wherein, X is a substituent having an electron-donating property] from deutrium to hydrogen or from hydrogen to deutrium.
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Page/Page column 23-24
(2008/06/13)
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- Deoxygenation and other photochemical reactions of aromatic selenoxides
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Atomic oxygen O(3P) is a potent oxidant that has been well-studied in the gas phase. However, exploration of its reactivity in the condensed organic phase has been hampered by the lack of an appropriate source. Dibenzothiophene-S-oxide (DBTO) and related derivatives have been promoted as photochemical D(3P) sources but suffer from low quantum yields. Photolysis of dibenzoselenophene-Se-oxide (DBSeO) results in the formation of dibenzoselenophene and oxidized solvent in significantly higher quantum yields, ca. 0.1. The oxidation product ratios from toluene obtained from the photolysis of dibenzothiophene-S-oxide and the corresponding selenoxide are the same, strongly suggesting a common oxidizing intermediate, which is taken to be O(3P). An additional product, proposed to be the corresponding selenenic ester, is also observed under deoxygenated conditions. The photochemistry of diphenyl selenoxide includes a minor portion of oxidant-forming deoxygenation, in contrast to previous conclusions.
- McCulla, Ryan D.,Jenks, William S.
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p. 16058 - 16065
(2007/10/03)
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- Synthesis of Cyclohexanol by Reduction of Pentachlorophenol using Raney Nickel-Aluminium Alloy in a BaO-D2O Solution under Sonication
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Reduction of pentachlorophenol (1) with Raney nickel-aluminium alloy in saturated BaO-D2O under sonication afforded cyclohexanol (2) in 85percent yield with a high -content (99percent).
- Mukumoto, Mamoru,Mashimo, Takuya,Tsuzuki, Hirohisa,Tsukinoki, Takehito,Uezu, Noriko,et al.
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p. 412 - 413
(2007/10/03)
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- Gas-phase oxygenation of benzene derivatives around 300 K with O(3P) atoms produced by microwave discharge of N2O. Part 2. Kinetic H/D isotope effects.
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The possible pathways for the formation of (chloro)phenol, following the addition of O(3P) to (chloro)benzene, have been examined using deuterated substrates: C6D6 (also in admixture with C6H6) and p-deuterochlorobenzene.Whereas with O-C6H6 adduct biradicals, loss of H* to give phenoxy radicals predominates, only one-third of the O-C5D6 intermediates undergo the corresponding reaction.Phenoxy radicals lead to phenol by transfer of an H(D) atom from cyclohexadienyl-type radicals, formed from H* (D*) and substrate.Analogously, in reactions of p-deuterochlorobenzene, loss of H is a major reaction after addition of an oxygen atom to a meta position, whereas loss of D (to give p-chlorophenol) occurs only with 35percent of the corresponding O(3P) adduct biradicals.The isotopic composition of phenol formed from p-DC6H4Cl (via p-DC6H4O*; generated by ipso substitution) revealed that H transfer to phenoxy radicals primarily gives the keto tautomers as major products.Isomerization of (chloro)benzene-O(3P) adduct biradicals to the corresponding phenols also appears to involve mainly, keto tautomers.The reaction of O(3P) with p-deuterochlorobenzene showed a slight change in the o/m/p distribution; this can be explained by the absence of a net secondary H/D isotope effect for O(3P) addition to the para site and a normal secondary isotope effect for meta addition.
- Sol, Veronica M.,Louw, Robert,Mulder, Peter
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p. 346 - 352
(2007/10/02)
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- SELECTIVE MONO- OR DIMETALATION OF ARENES BY MEANS OF SUPERBASIC REAGENTS
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If employed in tetrahydrofuran, stoichiometric amounts of butyllithium and potassium tert-butoxide react with benzene under clean monometalation.In hexane suspension, however, considerable amounts of meta- and para-disubstituted by-products are obtained (approx. 10percent).They become preponderant if a three-fold excess of the metalating agent is used.Naphthalene leads under the same conditions to a mixture of two mono- and ten di-substituted derivatives. - Alkyl groups, as present in tert-butylbenzene, retard the metalation at both m- and p-positions, while trialkylsilyl groups deactivate only m-position.In either case exclusive monosubstitution occurs. - Perdeuterobenzene undergoes metalation and subsequent electrophilic mono- or disubstitution to afford isotope labeled compounds with moderate, though synthetically attractive yields.The kinetic isotope effects and product ratios can be taken as evidence for aggregate formation at the level of both the superbasic metalating reagent and the organometallic intermediates.
- Schlosser, Manfred,Choi, Jung Hoon,Takagishi, Sadahito
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p. 5633 - 5648
(2007/10/02)
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