The use of ammonium halide salts as metal hydride precursors in a new Pd-catalyzed cycloisomerization of 1,6-diynes, which affords unexplored silylated 2-azafluorenes, is reported. This cascade process includes the addition of a Pd–hydride species to a π-system, intramolecular carbopalladation, and C­(sp2)–H bond activation. A variety of functional groups are tolerated, and the synthetic utility of the resulting products has been demonstrated by a series of derivatizations.

An enantiospecific palladium-catalyzed decarboxylative coupling of acyclic b,g-alkynoic acids with various aryl iodides to chiral tetrasubstituted allenes is described. The coupling reaction comprises adecarboxylative g-palladation of a,a-disubstituted carboxylica cids to providet he tetrasubstituted allenes with complete point-to-axial chirality transfer in excellent yields. Angewandte Chemie Communications 6547We thank Martina Prekel (University of Münster) for HPLC analysis and Nikolas Sandmann (University of Münster) for CD measurement instructions. Conflict of interestTheauthors declare no conflict of interest.

Palladium-catalyzed γ-arylation of acyclic β,γ-unsaturated carboxylic acids with various aryl iodides is reported. The cascade comprises a decarboxylative γ-palladation of β,γ-unsaturated α,α'-disubstituted carboxylic acids and subsequent C(sp)-C(sp) bond formation to provide diaryl vinyl methanes in moderate to good yields and high E/Z-selectivities. Reaction with an enantiomerically pure acid revealed that the process occurs with high stereospecificity.

Eine enantiospezifische Pd-katalysierte decarboxylierende Kupplungsreaktion von acyclischen b,g-Alkinsäuren mit verschiedenen Aryliodiden zu chiralen tetrasubstituierten Allenen wird beschrieben. Die Kupplungsreaktion umfasst eine decarboxylierende g-Palladierung von a,a-disubstituierten Carbonsäuren, um tetrasubstituierte Allene mit vollständiger Übertragung von Punkt-zu-axialer Chiralitäti ne xzellenten Ausbeuten aufzubauen.