Gerald Dyker

Transition Metal Catalyzed Coupling Reactions under C−H Activation

C-C coupling by transition metal catalyzed C-H activation has developed into a diverse area of research. The applicable catalysts are manifold, and the variety of products obtained range from basic chemicals to pharmaceuticals and building blocks for carbon networks. One reaction, in which several C-C bonds are formed under C-H activation of a methyl group, is the conversion of ortho-iodoanisole according to Equation (1).

Übergangsmetall-katalysierte Kupplungsreaktionen unter C-H-Aktivierung

DieC-C-Verknupfung durch Ubergangsmetall-katalysierte C-H-Aktivierung hat sich zu einem facettenreichen Forschungsgebiet entwickelt. Die einsetzbaren Katalysatoren sind vielfaltig, und die Produktpalette reicht von Grundchemikalien uber Pharmaka bis zu Bausteinen fur Kohlenstoffnetzwerke. Eine Reaktion, bei der mehrere C-C-Bindungen, unter anderem unter Aktivierung einer Methylgruppe, gebildet werden, ist die Umsetzung von ortho-Iodanisol gemas Gleichung (1).

A PALLADIUM CATALYZED DOMINO COUPLING PROCESS TO SUBSTITUTED PHENANTHRENES

Abstract A palladium catalyzed annulation reaction of diphenylacetylene with iodobenzene leads to 9,10-diphenylphenanthrene. The regiochemistry of this domino coupling process is studied, suggesting the cis-trans isomerization of vinyl palladium complexes as reactive intermediates.

A platinum-catalyzed annulation reaction leading to medium-sized rings

A platinum-catalyzed domino process with intermediate benzopyrylium cations reaches its optimum utility in the formation of 7- and 8-membered rings. With iron(III) chloride, a tetracyclic product is isolated, derived from an oxidative transformation of a metal-carbene intermediate.

First intermolecular palladium catalyzed arylation of an unfunctionalized aromatic hydrocarbon

Abstract Azulene is arylated by iodobenzene and by 4-nitro-chlorobenzene under palladium catalysis at the electron-rich 1-position.

Palladium-Catalyzed Arylation of Cyclopentadienes

Cyclopentadiene and metallocenes, typically zirconocene dichloride, are suitable substrates for multiple arylations with aryl bromides in palladium-catalyzed reactions. Thus, various aryl bromides bearing either an electron-donating or an electron-withdrawing substituent can react with these substrates to afford the corresponding 1,2,3,4,5-pentaaryl-1,3-cyclopentadienes in a single preparative step. Derivatives of cyclopentadiene, including di- and trisubstituted cyclopentadienes, and indene are arylated in a similar fashion.

Annulated ring-systems by Domino-Heck-aldol-condensation and Domino-Heck-Michael-addition processes

Abstract A palladium catalyzed coupling process of functionalized aryl bromides with allylic alcohols results in 5-membered ring annulation, whereas with homoallylic alcohols 6-membered rings are formed.

Spectroscopic Properties of Polycyclic Aromatic Compounds

Abstract Fluorescence emission spectra have been measured for acenaphthylene, aceanthrylene, acephenanthrylene, benz[ e ]aceanthrylene, 3-methylbenz[ j ]aceanthrylene, 6-methylbenz[ j ]aceanthrylene, benzo[ def ]cyclopenta[ hi ]chrysene, cyclopenta[ cd ]pyrene (also called acepyrylene) and acenaphth[1,2 a ]acenaphthylene in organic nonelectrolyte solvents of varying polarity. Benz[ e ]aceanthrylene was found to exhibit probe character for many of the solvents considered; however, emission intensity ratios in benzene, toluene, p -xylene and o -xylene were too small compared against nonelectrolyte solvents of similar polarity. The effect of nitromethane as selective quenching agent was also examined. Results of these measurements show that nitromethane does quench the fluorescence emission of the nine solutes studied, which is contrary to what would be expected based upon the fact that all nine solutes are nonalternant polycyclic aromatic hydrocarbons.

Palladium-catalyzed arylation of butadiynes

Abstract Diarylbutadiynes 1 undergo a palladium-catalyzed coupling reaction with aryl halides 2 to give tetraarylbutatrienes 3 , which may further react to benzofulvenes 6 depending on the reaction temperature and the type of aryl groups.

Oxidative Heterocyclization of 2‐Alkynylbenzaldehydes with 1,2‐Phenylenediamine

Upon condensation of ortho-phenylenediamine (2) with ortho-alkynylbenzaldehydes in nitrobenzene, oxidative cyclizations are observed, which result in benzimidazo[2,1-a]isoquinolines (8) or isoindolo[2,1-a]quinoxalines (9) depending on the influence of additional substituents at the alkyne.