Carbene-Catalyzed Aroylation of a 2-Chloroquinoxaline<i>N</i>-Oxide with Aromatic Aldehydes at Room Temperature
作者:Jan Maichrowski、Aman Bhasin、Florenz Sasse、Dieter E. Kaufmann
DOI:10.1002/ejoc.201402252
日期:2014.7
12 new biologically promising aroylquinoxaline N-oxides were synthesized through carbene-catalyzedaroylation of the chloro nitrone unit with different aromaticaldehydes in the presence of 1,3-dimethylimidazolium iodide as the carbene precursor. The optimized reaction conditions tolerated a broad bandwidth of aldehydes and allowed the synthesis of the corresponding ketones in yields up to 87 %. Studies
Efficient Synthesis of Quinoxaline Derivatives by Selective Modification of 3-Chloro-6-fluoroquinoxalin-2(1<i>H</i>)-one 4-Oxide
作者:Jan Maichrowski、Mimoza Gjikaj、Eike G. Hübner、Bärbel Bergmann、Ingrid B. Müller、Dieter E. Kaufmann
DOI:10.1002/ejoc.201201569
日期:2013.4
The readily available and polyfunctionalized 3-chloro-6-fluoroquinoxalin-2(1H)-one4-oxide, derived from the efficient one-step annulation reaction of 1,1,2-trichloro-2-nitroethene with 4-fluoroaniline, was selectively modified at the chloronitrone and the amide units, leading to more than 30 new quinoxalinederivatives with a unique substitution pattern in good to excellent yields. In addition, the
Palladium-Catalyzed Cross-Coupling of 2-Chloroquinoxaline<i>N</i>-Oxides with Arylboronic Acids
作者:Jan Maichrowski、Eike G. Hübner、Dieter E. Kaufmann
DOI:10.1002/ejoc.201300707
日期:2013.12
96 %. This first efficient Pd-catalyzed Suzuki–Miyaura reaction of chloroquinoxaline N-oxides with arylboronicacids led to new 2-arylquinoxaline N-oxides. The scope and limitations of this arylation reaction were investigated, and the role of some sterically demanding boronic acids in the cross-coupling reaction was evaluated by means of DFT calculations. Additionally, the Pd-catalyzed C-arylation of
Chemistry of Halonitroethenes, Part 2: Trichloronitroethene as a Building Block for the Novel Synthesis of 5-Chloro(nitro)methyl-Substituted 1-Aryltetrazoles
derivative was proven by single-crystal X-ray diffraction analysis. Starting from arenediamines, this reaction affords bistetrazoles. In addition, the tetrazoles are interesting starting materials for further conversions of the sidechain. nitro compounds - nucleophilicsubstitution - amidines - arenes - heterocycles - tetrazoles
Chemistry of Polyhalogenated
Nitrobutadienes, Part 7: A Novel Synthetic Access to Chlorinated
Nitrile Oxides
作者:Dieter Kaufmann、Eva Nutz、Viktor Zapol’skii
DOI:10.1055/s-0029-1216906
日期:——
Reaction of gem-dichloronitroalkenes with base leads to the formation of chlorinated nitrile oxides, probably via a cyclic intermediate. The 1,3-dipoles can be trapped with alkenes to give dihydroisoxazoles with a chlorinated side chain in 3-position. This novel synthetic method is fairly general.