LongLarf

The Cover Feature shows the direct synthesis of 1‐propanol from CO₂, H₂, and ethene. This process includes two steps: the hydrogenation of CO₂ to CO by reverse water‐gas shift reaction and subsequent hyroformylation of ethene with the formed CO and hydrogen. Gold nanoparticles together with alkali dopants are responsible for reactant activation. More information can be found in the Full Paper by Heyl et al. on page 651 in Issue 3, 2019 (DOI: https://doi.org/10.1002/cssc.20180193710.1002/cssc.201801937).

Pyrimidopteridine N ‐oxide‐based heterocycles exhibit excellent excited state reduction potentials paired with a suitable ground state reduction potential allowing for catalyst turnover with mild oxidants. The structural similarity between pyrimidopteridines and recently uncovered flavine N ‐oxides may draw an important link between organic photoredox catalysis and chemical biology.

Abstract

Herein we report the photo‐ and electrochemical characterization of pyrimidopteridine N‐oxide‐based heterocycles. The potential of their application as organic photoredox catalysts is showcased in the photomediated contra‐thermodynamic E→Z isomerization of cinnamic acid derivatives and oxidative cyclization of 2‐phenyl benzoic acid to benzocoumarin using molecular oxygen as a mild oxidant. Furthermore, unprecedented intermolecular non‐covalent n–π‐hole interactions in solid state are discussed based on crystallographic and theoretical data.

Clean and green by radicals: 1,3‐Dihydroxylacetone, a biomass‐based platform molecule has been oxidized with 100 % carbon atom efficiency at room temperature to valuable glycolic acid, formamides and formates by a cheap non‐noble metal catalyst. Radical‐based mechanisms were discovered by in situ EPR with spin traps and operando ATR‐IR spectroscopy.

Abstract

Glycolic acid (GA), as important building block of biodegradable polymers, has been synthesized for the first time in excellent yields at room temperature by selective oxidation of 1,3‐dihyroxyacetone (DHA) using a cheap supported Cu/Al₂O₃ catalyst with single active Cu^II species. By combining EPR spin‐trapping and operando ATR‐IR experiments, different mechanisms for the co‐synthesis of GA, formates, and formamides have been derived, in which ^.OH radicals formed from H₂O₂ by a Fenton‐like reaction play a key role.

Pyrimidopteridine N ‐oxide‐based heterocycles exhibit excellent excited state reduction potentials paired with a suitable ground state reduction potential allowing for catalyst turnover with mild oxidants. The structural similarity between pyrimidopteridines and recently uncovered flavine N ‐oxides may draw an important link between organic photoredox catalysis and chemical biology.

Abstract

Herein we report the photo‐ and electrochemical characterization of pyrimidopteridine N‐oxide‐based heterocycles. The potential of their application as organic photoredox catalysts is showcased in the photomediated contra‐thermodynamic E→Z isomerization of cinnamic acid derivatives and oxidative cyclization of 2‐phenyl benzoic acid to benzocoumarin using molecular oxygen as a mild oxidant. Furthermore, unprecedented intermolecular non‐covalent n–π‐hole interactions in solid state are discussed based on crystallographic and theoretical data.

“Although the same basics of photocatalysis unite applications in artificial photosynthesis, photoreformation, photoredox catalysis and photodynamic therapy, they are being developed in surprising isolation. … This editorial is a call to join forces and embrace progress in all of these areas to enable accelerated development of a more holistic science in photocatalysis. …” Read more in the Guest Editorial by E. Reisner.

Deacylative transformations of ketones via aromatization-promoted C–C bond activation

Deacylative transformations of ketones via aromatization-promoted C–C bond activation, Published online: 30 January 2019; doi:10.1038/s41586-019-0926-8

“My favorite motto is be good, be happy, be motivated. My biggest motivation is to overcome challenges …” Find out more about Xiao‐Feng Wu in his Author Profile.

Synlett
DOI: 10.1055/s-0037-1611669

The asymmetric transfer hydrogenation of ketones using isopropyl alcohol (IPA) as hydrogen donor in the presence of novel manganese catalysts is explored. The selective and active systems are easily generated in situ from [MnBr(CO)5] and inexpensive C 2-symmeric bisoxalamide ligands. Under the optimized reaction conditions, the Mn-derived catalyst gave higher enantioselectivity compared with the related ruthenium catalyst.
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Georg Thieme Verlag Stuttgart · New York

Article in Thieme eJournals:
Table of contents  |  Abstract  |  open access Full text

Full control over the selectivity of carbon–carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach. We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)^(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.

Bimolecular nucleophilic substitution (S_N2) plays a central role in organic chemistry. In the conventionally accepted mechanism, the nucleophile displaces a carbon-bound leaving group X, often a halogen, by attacking the carbon face opposite the C–X bond. A less common variant, the halogenophilic S_N2X reaction, involves initial nucleophilic attack of the X group from the front and as such is less sensitive to backside steric hindrance. Herein, we report an enantioconvergent substitution reaction of activated tertiary bromides by thiocarboxylates or azides that, on the basis of experimental and computational mechanistic studies, appears to proceed via the unusual S_N2X pathway. The proposed electrophilic intermediates, benzoylsulfenyl bromide and bromine azide, were independently synthesized and shown to be effective.