Results 81 to 90 of about 27,486 (241)

Synthesis of Anthraquinones by Iridium-Catalyzed [2 + 2 + 2] Cycloaddition of a 1,2-Bis(propiolyl)benzene Derivative with Alkynes

Inorganics, 2019
[2 + 2 + 2] cycloaddition of a 1,2-bis(propiolyl)benzene derivative with terminal and internal alkynes takes place in the presence of [Ir(cod)Cl]2 (cod = 1,5-cyclooctadiene) combined with bis(diphenylphosphino)ethane (DPPE) to give anthraquinones in 42 ...
Takahiro Sawano, Yuko Toyoshima, Ryo Takeuchi   +2 more
doaj   +1 more source

Generation of the Camptothecin Scaffold by a Flavin‐Catalyzed Photooxidative Skeletal Reorganization

Angewandte Chemie, EarlyView.
The biosynthetic pathway of the anticancer drug precursor camptothecin involves an enigmatic skeletal reorganization from a 6/5/6 tetrahydro‐β‐carboline to a 6/6/5 pyrroloquinoline ring system. Here, we show that this transformation can be achieved by photooxidation with flavin cofactors, such as flavin mononucleotide (FMN) as catalysts.
Shenyu Liu, Zeliang Zhang, Benedikt Seligmann, Van Hung Bui, Tuan‐Anh Minh Nguyen, Thu‐Thuy T. Dang, Jakob Franke   +6 more
wiley   +2 more sources

Application of chiral 2-isoxazoline for the synthesis of syn-1,3-diol analogs

Beilstein Journal of Organic Chemistry, 2019
The asymmetric cycloaddition of TIPS nitronate catalyzed by “Cu(II)-bisoxazoline” gave the 2-isoxazoline product in 95% yield, which was converted into tert-butyl (3S,5R)-6-hydroxy-3,5-O-isopropylidene-3,5-dihydroxyhexanoate in 14 steps through a β ...
Juanjuan Feng, Tianyu Li, Jiaxin Zhang, Peng Jiao   +3 more
doaj   +1 more source

Photochemisch erzeugte Oxetane als Schlüssel zur endergonen Cyclopropansynthese

Angewandte Chemie, EarlyView.
Eine neuartige Oxetan‐zu‐Cyclopropan‐Umlagerung eröffnet einen atomökonomischen Zugang zu dicht funktionalisierten Cyclopropanen aus Furanen und photochemisch aktivierten Aldehyden. Die erhaltenen Strukturen erschließen komplexe bioaktive Motive und fungieren als vielseitige Plattform für die asymmetrische Cyclopropansynthese.
Tim Köglmeier, Thomas J. Tiefel, Oliver Reiser   +2 more
wiley   +1 more source

Kinetically Stable Boron‐Heteroatom Bonds

Angewandte Chemie, EarlyView.
This study investigates the kinetic stability of boron‐heteroatom bonds in N‐methyliminodiacetic acid (MIDA) boronates. The hemilabile nature of the ligand enables the synthesis of molecules that would otherwise be considered too hydrolytically labile. Depending on the structure, acid‐promoted migration of the boryl group was found to produce compounds
Alina Trofimova, Ben Zhen Huang, Harjeet S. Soor, Brandon White, Aleksandra Holownia, Yury Lebedev, Alan J. Lough, Travis Dudding, Andrei K. Yudin   +8 more
wiley   +2 more sources

Photochemical Reaction Discovery Enabled by the Dynamic Speciation of Copper Complexes

Angewandte Chemie, EarlyView.
A strategy for accelerated photochemical reaction discovery is reported that harnesses the dynamic speciation of copper complexes, driven by their labile metal–ligand bonds. This platform simplifies reaction screening by combining an earth‐abundant copper(II) salt with commercially available ligands, which reversibly generate multiple catalytic species
Alessio Regni, Siyu Liang, Supreeta Sen, Hailey Hendricks, Xijue Wu, Matthew V. Pecoraro, Jose B. Roque   +6 more
wiley   +2 more sources

Catalytic cycloaddition of acrylates to norbornadiene. Kinetics and mechanism

Тонкие химические технологии, 2010
Kinetics of [2+2+2]-cycloaddition of acrylates to norbornadiene in the presence of η3-bis(allyl) nickel was studied. The thermodynamic parameters were determined. Kinetics equations for all of the isomer reaction products were found.
I. E. Efros, O. A. Nikityuk, D. V. Dmitriev, V. R. Flid   +3 more
doaj  

Excited‐State Antiaromaticity in Nonbenzenoid Aromatics: Examining the Dynamics of Intramolecular Proton Transfer With a Small Driving Force

Angewandte Chemie, EarlyView.
The excited‐state antiaromaticity of hydroxybenzotropyliums (HBTs) can be tuned through substituent effects to bring the aromatic ‘enol’ (E) and keto (K) tautomers close in energy. This leads to abnormally slow excited‐state proton transfer (on the ns timescale), giving rise to dual fluorescence emission and weak photoacidity.
Promeet K. Saha, Charlotte A. Bardsley, Hector G. Miranda‐Salinas, Daniel Crane, Rabia Ayub, Andrew P. Monkman, Paul R. McGonigal   +6 more
wiley   +2 more sources

Silicon‐Bridged Homocyclopentadienides: Metal‐Assisted Facile Ring Expansion of Cyclopentadienide by Transient Imino(Metallophosphino)Silylenes

Angewandte Chemie, EarlyView.
We demonstrate the facile aromatic C─C bond cleavage of cyclopentadienide mediated by transient imino(metallophosphino)silylenes, enabling the transformation of an aromatic system into a homoaromatic species. The steric bulk of the phosphino substituent, together with the weak interaction between the coinage metal and the cyclopentadienide ligand, are ...
Huaiyuan Zhu, Xufang Liu, Shicheng Dong, Jun Zhu, Shigeyoshi Inoue   +4 more
wiley   +2 more sources

An NHC‐Coordinated Silicon/Sulfur Analogue of an Acyl Carbene

Angewandte Chemie, EarlyView.
An NHC complex of an Si/S analogue of an acyl carbene is synthesized by the reaction of a disilyne with a cyclic thiourea. The observed Si2S three‐membered ring with unsymmetrical Si─S distances and a Si─Si single bond is consistent with intramolecular coordination of the silathioacyl sulfur to the silylene center.
Takuto Toyooka, Shintaro Ishida, Takeaki Iwamoto   +2 more
wiley   +2 more sources