José F. Rodríguez

Palladium-Catalyzed Hydrohalogenation of 1,6-Enynes: Hydrogen Halide Salts and Alkyl Halides as Convenient HX Surrogates

Difficulties associated with handling H2 and CO in metal-catalyzed processes have led to the development of chemical surrogates to these species. Despite many successful examples using this strategy, the application of convenient hydrogen halide (HX) surrogates in catalysis has lagged behind considerably. We now report the use of ammonium halides as HX surrogates to accomplish a Pd-catalyzed hydrohalogenation of enynes. These safe and practical salts avoid many drawbacks associated with traditional HX sources including toxicity and corrosiveness. Experimental and computational studies support a reaction mechanism involving a crucial E-to-Z vinyl-Pd isomerization and a carbon-halogen bond-forming reductive elimination. Furthermore, rare examples of C(sp3)-Br and -Cl reductive elimination from Pd(II) as well as transfer hydroiodination using 1-iodobutane as an alternate HI surrogate are also presented.

Palladium-Catalyzed Synthesis of Dihydrobenzoindolones via C–H Bond Activation and Alkyne Insertion

A palladium-catalyzed intramolecular carbopalladation, intramolecular C-H bond activation, and alkyne insertion sequence for the generation of dihydrobenzoindolones is described. Products are obtained in moderate to excellent yields as single regioisomers. Various functional groups on both reaction partners were tolerated, and the scalability of this method was determined.

Palladium-Catalyzed Hydride Addition/C–H Bond Activation Cascade: Cycloisomerization of 1,6-Diynes

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.