Frontispiece: gem ‐Dichlorocyclopropanation of Dicarbonyl Derivatives

Capillary electrophoresis of o-phenylenediamine derivatives (quinoxalines) of dicarbonyl sugars

Dicarbonyl sugars were separated by capillary electrophoresis as o-phenylenediamine derivatives (quinoxalines). Tetrabutylammonium bromide was used as a modifier; n-arabino-2-hexosulose (n-glucosone), D-lyxo-2-hexostdose (D-gdaCtOSOnC), 7-deoxy-L-galacto-2-hexosulose and 5-hydroxy-2,3dioxohexanal served as standards. The separation procedure was optimized with respect to pH, buffer and solute c...

Organocatalytic Asymmetric α-Chlorination of 1, 3-Dicarbonyl Compounds Catalyzed by 2-Aminobenzimidazole Derivatives

Bifunctional chiral 2-aminobenzimidazole derivatives 1 and 2 catalyze the enantioselective stereodivergent α-chlorination of β-ketoesters and 1,3-diketone derivatives with up to 50% ee using N-chlorosuccinimide (NCS) or 2,3,4,4,5,6-hexachloro-2,5-cyclohexadien-1-one as electrophilic chlorine sources.

Preparation of imidazo[1,2-a]-N-heterocyclic derivatives with gem-difluorinated side chains

Using an aerobic oxidative coupling, different new imidazo[1,2-a]-N-heterocycles with gem-difluroroalkyl side chains have been prepared in fair yields by the reaction of gem-difluoroenones with aminopyridines, -pyrimidines and -pyridazines. Condensed heterocycles of this type play an important role as key core structures of various bioactive compounds. Further, starting with a chloroimidazopyri...

Gem- And Co-Gem-Free Graphs Have Bounded Clique-Width

The P4 is the induced path of four vertices. The gem consists of a P4 with an additional universal vertex being completely adjacent to the P4, and the co-gem is its complement graph. Gemand co-gem-free graphs generalize the popular class of cographs (i. e. P4-free graphs). The tree structure and algebraic generation of cographs has been crucial for several concepts of graph decomposition such a...

A Gem of Official Literature