Article
Chemistry, Multidisciplinary
Panxia Zhao, Jie Chen, Nana Ma, Jingfei Chen, Xiangquan Qin, Chuanfei Liu, Fuquan Yao, Lishan Yao, Longyi Jin, Zhiqi Cong
Summary: The study demonstrates the efficient H2O2-dependent (R)-enantioselective epoxidation of unfunctionalized styrene and its derivatives by site-mutated variants of a unique non-natural P450BM3 peroxygenase in combination with a dual-functional small molecule. The synergistic use of protein engineering and an exogenous DFSM represents an effective strategy to control the enantioselectivity of styrene epoxidation, significantly expanding the chemical scope of P450 enzymes as useful bio-oxidative catalysts.
Article
Chemistry, Physical
Hu Xiao, Shuang Dong, Yan Liu, Xiao-Qiong Pei, Hui Lin, Zhong-Liu Wu
Summary: New (R)-selective styrene monooxygenases have been identified, showing high enantioselectivity in converting styrene analogues into (R)-epoxides with purity up to >99% ee. Site 46 was identified as a critical residue affecting the enantioselectivity of SMOs, providing a valuable green alternative for the synthesis of enantiopure (R)-epoxides.
CATALYSIS SCIENCE & TECHNOLOGY
(2021)
Article
Chemistry, Organic
Yuchi Zhang, Asma Iqbal, Jiantao Zai, Shu-Yu Zhang, Hongran Guo, Xuejiao Liu, Ibrahim ul Islam, Hira Fazal, Xuefeng Qian
Summary: Olefin epoxidation is a crucial reaction in the chemical industry, and traditional methods have drawbacks. Electro-epoxidation offers an eco-friendly alternative, with GF-CoS2/CoS heterostructures found to efficiently generate bromine redox species for improved epoxidation selectivity. The strategy shows promise for technical applications due to its simplicity and energy-saving advantages.
ORGANIC CHEMISTRY FRONTIERS
(2022)
Article
Chemistry, Multidisciplinary
Pooja Chaudhary, Geeta Devi Yadav, Krishna K. Damodaran, Surendra Singh
Summary: New chiral Mn(III)-salen complexes were synthesized and evaluated for the asymmetric epoxidation of styrene, showing high yields and promising catalytic activity; the recovered catalysts could be reused for multiple runs, demonstrating good stability and durability.
NEW JOURNAL OF CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Matthieu Balas, Asma Mayoufi, Richard Villanneau, Franck Launay
Summary: Since its first report in the early 1990s, Mukaiyama-type aerobic epoxidation involving the presence of an aldehyde as an electron donor is considered as an interesting oxidation reaction. Among the various metal catalysts efficient for this process, salen-type complexes have many advantages: i) cheap Schiff-base ligands can be easily synthesized and functionalized, ii) their metal complexes are described with most transition metals from the periodic table and iii) these compounds are also efficient for the catalytic formation of cyclic carbonates from epoxides and CO2, which makes them ideal candidates for the oxidative carboxylation of alkenes. The present work aimed at revisiting the aerobic oxidation of styrene using Cr(iii) and Mn(iii) salen complexes in the presence of isobutyraldehyde with the idea to further use these complexes (without any work-up), as co-catalysts for the formation of styrene carbonate under CO2 pressure. However, contrary to what is often described in the literature, the present study showed that the introduction of a metal catalyst is not necessary for the epoxidation of styrene at 80 degrees C in benzonitrile. In our hands, yields of ca. 15% of styrene carbonate were obtained from styrene using O-2 (3.5 bar) and CO2 (11 bar) as reagents in the presence of isobutyraldehyde (2.5 eq), tetrabutylammonium bromide (ca. 2 mol%) and the Cr(iii) salen complex (ca. 1 mol%). Apparently, the oxidation of Cr(iii) to Cr(vi) species in the presence of O-2 and isobutyraldehyde is detrimental to the kinetics of the tetrabutylammonium bromide-catalyzed cycloaddition of CO2 to styrene oxide.
REACTION CHEMISTRY & ENGINEERING
(2023)
Article
Chemistry, Physical
Yu-Jhang Lu, Damodar Janmanchi, Thiyagarajan Natarajan, Zhi-Han Lin, Wondemagegn H. Wanna, I-Jui Hsu, Der-Lii M. Tzou, Tigist Ayalew Abay, Steve S-F Yu
Summary: We investigated the catalytic epoxidation of cyclohexene and styrene using AgCN powder as a catalyst in CH3CN. The reaction mixtures separated into organic and aqueous layers easily. We achieved high selectivity in the production of cyclohexene oxide and styrene oxide. The AgCN particles could be recycled and reused through various analytical techniques.
Article
Chemistry, Inorganic & Nuclear
Tingting Gu, Isaac Kwaku Attatsi, Weihua Zhu, Minzhi Li, Samuel A. Ndur, Xu Liang
Summary: In this study, Co(II)phthalocyanine was successfully immobilized on multiwalled carbon nanotubes, showing superior performance in electrocatalysis for hydrogen evolution reactions. The material paves the way for designing efficient energy production and storage devices, indicating high efficiency in catalyzing hydrogen evolution.
INORGANICA CHIMICA ACTA
(2022)
Review
Chemistry, Organic
Maria Kourgiantaki, Georgia G. G. Bagkavou, Christos I. I. Stathakis, Alexandros L. L. Zografos
Summary: The necessity for selective oxidative transformations in the synthesis of complex natural compounds like sesquiterpenoids has led to the development of powerful and widely applicable methods in total synthesis. Recent synthetic efforts have focused on radical approaches similar to monooxygenases to address the challenge of installing an 'oxidase phase' in the carbocycles of sesquiterpenoids. This review summarizes recent total syntheses of sesquiterpenoids using radical reactions for allylic hydroxylations, hydrations, and C-H oxidations.
ORGANIC CHEMISTRY FRONTIERS
(2023)
Article
Chemistry, Inorganic & Nuclear
M. Angeles Navarro, Juan Amaro-Gahete, Jose R. Ruiz, Cesar Jimenez-Sanchidrian, Francisco J. Romero-Salguero, Dolores Esquivel
Summary: A new heterogeneous catalyst with excellent catalytic performance has been synthesized by immobilizing a copper complex on a surface-functionalized ordered mesoporous organosilica. The catalyst showed high conversion and selectivity in the epoxidation reaction.
DALTON TRANSACTIONS
(2022)
Review
Chemistry, Multidisciplinary
Mohamed M. Hammouda, Khaled M. Elattar
Summary: This review summarizes the recent advancements in the synthesis and chemistry of compounds containing a beta-aminoketone core, highlighting their synthetic strategies, chemical reactivity, and mechanistic pathways. The review provides detailed information on the synthesis of various compounds and their applications in different fields.
Article
Chemistry, Physical
Dong Han, Yuanfeng Li, Ya-Ping Han, Hong-Yu Zhang, Yuecheng Zhang, Jiquan Zhao
Summary: In this study, four different sidearm-containing Salen-Mn(III) complexes were synthesized and compared. It was found that the complex with a D-Boc-N-proline sidearm exhibited the best catalytic activity in the asymmetric epoxidation reaction. The steric hindrance and appropriate configuration of this sidearm facilitated the approach of olefins to the active center, resulting in improved reaction yields and enantioselectivities.
MOLECULAR CATALYSIS
(2022)
Article
Polymer Science
Shun Ohta, Keigo Itoh, Tomoyuki Toda, Kei Nishii, Masaaki Okazaki
Summary: Olefin polymerization reactions mediated by diamido-supported titanium complexes are part of post-metallocene studies. The 2/MMAO catalyst system exhibits high activity for ethylene and propylene polymerization.
