Article
Chemistry, Physical
Philip L. Hahn, Jared M. Lowe, Yubo Xu, Kevin L. Burns, Michael K. Hilinski
Summary: In this study, an organocatalytic approach using secondary amines as catalysts foroxaziridinium-mediated C-H hydroxylation is introduced. The operationally simple catalytic strategy demonstrated advantages in achieving high yielding and highly selective remote hydroxylation of compounds with oxidation-sensitive functional groups. Hexafluoroisopropanol was used as the solvent in the absence of water, leading to a proposed hydrogen-bonding effect that resulted in high chemoselectivity for remote aliphatic hydroxylation of 2 degrees alcohols.
Article
Chemistry, Multidisciplinary
Christina Wartmann, Shiny Nandi, Joerg-Martin Neudoerfl, Albrecht Berkessel
Summary: The titanium complex of the cis-1,2-diaminocyclohexane (cis-DACH) derived Berkessel-salalen ligand is a highly efficient and enantioselective catalyst for the asymmetric epoxidation of terminal olefins with hydrogen peroxide. This study also found that this epoxidation catalyst can effectively perform the highly enantioselective hydroxylation of benzylic C-H bonds with hydrogen peroxide. A newly optimized nitro-salalen Ti-catalyst showed the highest efficiency ever reported for asymmetric catalytic benzylic hydroxylation, with enantioselectivities of up to 98% ee, while overoxidation to ketone is marginal. The novel nitro-salalen Ti-catalyst also exhibited enhanced epoxidation efficiency, with a conversion of 1-decene to its epoxide in 90% yield and 94% ee at a catalyst loading of only 0.1mol-%.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Laia Vicens, Massimo Bietti, Miquel Costas
Summary: The use of bioinspired manganese catalysts and H2O2 under mild conditions allows for the efficient preparation of modified alpha-amino acids. This method demonstrates outstanding site-selectivity and diastereoselectivity, potentially serving as an alternative to established organometallic procedures.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Roman Ottenbacher, Anna A. Bryliakova, Mikhail Shashkov, Evgenii P. Talsi, Konstantin P. Bryliakov
Summary: This study demonstrates the oxidation of aliphatic C-H bonds using bioinspired catalyst systems in acetonitrile, yielding a mixture of alcohols and esters. The oxygen atom sources for alcohol and ester formation were identified through isotopic labeling studies. The mechanism of C-H oxidations catalyzed by bioinspired Mn complexes and the factors influencing the alcohol/ester ratios were revealed.
Article
Chemistry, Multidisciplinary
Chang Liu, Zixun Yu, Fangxin She, Jiaxiang Chen, Fangzhou Liu, Jiangtao Qu, Julie M. Cairney, Chongchong Wu, Kailong Liu, Weijie Yang, Huiling Zheng, Yuan Chen, Hao Li, Li Wei
Summary: By constructing heterogeneous molecular catalysts using cobalt porphyrins and carbon nanotubes, the catalytic properties and activity were successfully modulated, resulting in sustainable production of hydrogen peroxide with high selectivity and activity.
ENERGY & ENVIRONMENTAL SCIENCE
(2023)
Article
Chemistry, Multidisciplinary
Chul-Ho Yun, Jinhyun Kim, Frank Hollmann, Chan Beum Park
Summary: This article critically summarizes the current developments in photoredox biocatalysis, highlighting promising concepts and discussing current limitations.
Article
Chemistry, Multidisciplinary
Fen Su, Fengfei Lu, Kun Tang, Xiaokang Lv, Zhongfu Luo, Fengrui Che, Hongyan Long, Xingxing Wu, Yonggui Robin Chi
Summary: This study discloses the first organocatalytic direct functionalization/acylation of inert C(sp3)-H bonds of completely unfunctionalized alkanes. The approach involves N-heterocyclic carbene catalyst-mediated carbonyl radical intermediate generation and coupling with simple alkanes through the corresponding alkyl radical intermediates generated via a hydrogen atom transfer process. This method provides a new avenue for functionalization of challenging C-H bonds.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Yunfei Ge, Xingxing Su, Guijie Li, Yun-Fang Yang, Yuanbin She
Summary: An oxidative functionalization of naphthalene and its derivatives catalyzed by fluorine-containing porphyrin Mn(TFPP)Cl or non-fluorine-containing porphyrin Mn(TPP)Cl is reported, showing that the catalysts play a significant role in the reactions. These studies will provide valuable guidance for the development of metalloporphyrin-catalyzed C-H bond oxidative functionalization.
TETRAHEDRON LETTERS
(2023)
Article
Chemistry, Inorganic & Nuclear
Zhimin Wu, Dongru Sun, Yong-Min Lee, Yufen Zhao, Wonwoo Nam, Yong Wang
Summary: The novel free radical chain mechanism of the Ni(II)-mediated oxidation of cyclohexane by mCPBA is investigated using density functional theory calculations. The involvement of a long speculated Ni-II-oxyl species is ruled out, and it is found that an aroyloxy radical (mCBA) and a Ni-III-hydroxyl species formed by O-O homolysis of a Ni-II-mCPBA complex are the active species in the C-H bond activation. These mechanistic findings support the free radical chain mechanism and enrich the mechanistic knowledge of metal-peracid oxidation systems containing transition metals after group 8.
DALTON TRANSACTIONS
(2023)
Article
Chemistry, Multidisciplinary
Yongtao Wang, Rui Lu, Jia Yao, Haoran Li
Summary: This study highlights the critical role of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) in the aerobic alpha-hydroxylation of ketones, showing its ability to enhance the oxidizing ability of peroxide intermediates. Experimental and theoretical investigations were conducted to study the mechanism, confirming the presence of double hydrogen bonds between TBD and ketones. The findings suggest the potential application of TBD as a catalyst for oxidations.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Physical
Eduard Masferrer-Rius, Fanshi Li, Martin Lutz, Robertus J. M. Klein Gebbink
Summary: This study reports on the exploration of new biologically inspired manganese and iron complexes in enantioselective oxidation catalysis, showing the potential for enhancing enantioselectivities by tuning the environment around the catalytic active site. Using optimized conditions, manganese complex 2 exhibited effective enantioselective benzylic oxidation of a series of arylalkane substrates. Additionally, the new 4-pyrrolidinopyridine-based complexes showed promise in the asymmetric epoxidation of olefins.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
Article
Engineering, Environmental
Sihyun An, Younggun Yoon, Jae-Hyung Ahn, Dayeon Kim, Hang-Yeon Weon, Ye-eun Kim, Hor-Gil Hur, Youri Yang
Summary: The Bio-Fenton reaction was used to degrade bisphenol A (BPA), a commonly used plastic additive, by in-situ generated hydrogen peroxide (H2O2). The reaction conditions included glucose oxidase (GOx), glucose, and Fe(III)citrate at pH 5.3. The reaction produced center dot OH, which contributed significantly to BPA degradation.
JOURNAL OF ENVIRONMENTAL CHEMICAL ENGINEERING
(2023)
Article
Chemistry, Inorganic & Nuclear
Artur Hermano Sampaio Dias, Rolly Yadav, Thirakorn Mokkawes, Asheesh Kumar, Munir S. Skaf, Chivukula Sastri, Devesh Kumar, Sam P. de Visser
Summary: BPA is used as a precursor in the synthesis of plastics, but its presence in the environment is causing toxicity as an endocrine-disrupting chemical. Through computational studies, we have found that P450 2C9 converts BPA into hydroxycumyl alcohol as the main product. The low spin state and the properties of the substrate play important roles in determining the reaction pathway and product distribution.
INORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Ngoc Tan Cao, Ngoc Anh Nguyen, Thien-Kim Le, Gun Su Cha, Ki Deok Park, Chul-Ho Yun
Summary: Oleanolic acid (OA) is a pentacyclic triterpenoid with beneficial properties for humans, mainly metabolized by the enzyme CYP3A4 to produce 4-epi-hederagenenin as a major metabolite. This metabolization process may impact drug-food interactions.
Article
Chemistry, Physical
Barbara Ticconi, Giorgio Capocasa, Andrea Cerrato, Stefano Di Stefano, Andrea Lapi, Beatrice Marincioni, Giorgio Olivo, Osvaldo Lanzalunga
Summary: A series of alkylaromatic compounds underwent selective aromatic ring hydroxylation catalyzed by a newly prepared imine-based non-heme iron complex with H2O2, rather than side-chain oxidation. Analysis of the oxidation products revealed that the side-chain/ring oxygenated product ratio increased as the bond dissociation energy of the benzylic C-H bond decreased.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
