Cover Picture: Measuring the Relative Reactivity of the Carbon–Hydrogen Bonds of Alkanes as Nucleophiles (Angew. Chem. Int. Ed. 42/2018)

Titelbild: Measuring the Relative Reactivity of the Carbon–Hydrogen Bonds of Alkanes as Nucleophiles (Angew. Chem. 42/2018)

Acceptorless dehydrogenative condensation: synthesis of indoles and quinolines from diols and anilines.

The use of diols and anilines as reagents for the preparation of indoles represents a challenge in organic synthesis. By means of acceptorless dehydrogenative condensation, heterocycles, such as indoles, can be obtained. Herein we present an experimental and theoretical study for this purpose employing heterogeneous catalysts Pt/Al2O3 and ZnO in combination with an acid catalyst (p-TSA) and NMP as solvent. Under our optimized conditions, the diol excess has been reduced down to 2 equivalents. This represents a major advance, and allows the use of other diols. 2,3-Butanediol or 1,2-cyclohexanediol has been employed affording 2,3-dimethyl indoles and tetrahydrocarbazoles. In addition, 1,3-pro…

Compuestos heterocíclicos en catálisis

Los compuestos heterocíclicos son farmacológicamente activos en muchos casos y se accede a ellos tanto por síntesis química como a partir de fuentes naturales. Además, también son de considerable interés debido a su utilidad sintética como intermedios reactivos, grupos protectores, auxiliares quirales, catalizadores orgánicos o ligandos en complejos metálicos. Por lo tanto, la síntesis de compuestos heterocíclicos ha sido uno de los objetivos de investigación en química orgánica. En este sentido, la catálisis por metales de transición constituye una de las metodologías más atractivas para la preparación de estos compuestos de alto valor añadido ya que permite alcanzar variedad y complejidad…

Measuring the Relative Reactivity of the Carbon-Hydrogen Bonds of Alkanes as Nucleophiles

We report quantitative measurements of the relative reactivities of a series of C-H bonds of gaseous or liquid CnH2n+2 alkanes (n = 1-8, 29 different C-H bonds) towards insitu generated electrophiles (copper, silver, and rhodium carbenes), with methane as the reference. This strategy surpasses the drawback of previous model reactions of alkanes with strong electrophiles suffering from C-C cleavage processes, which precluded direct comparison of the relative reactivities of alkane C-H bonds.

Palladium-Catalyzed C-C Ring Closure in α-Chloromethylimines: Synthesis of 1H -Indoles

6-Amino-7-Azaindoles synthesis from 2,6-diamino pyridine and diols

Abstract 6-Amino-7-azaindole has been prepared by combination of diaminopyridine and diols by means of an acceptorless dehydrogenative condensation. In addition, amino pyridines may also yield towards pyrrolo[3,2-b]pyrrole systems. All of these transformation have been performed with accessible heterogeneous catalysts: Pd/C and ZnO.