Search

A new transition-metal-free synthetic method for C–O coupling between various aryl halides and alkoxides is described. This type of transformation is typically accomplished using palladium catalysts containing a specialized phosphine ligand. The reactions reported here can be performed under mild, ambient conditions using certain potassium alkoxides and a range of aryl halides, with iodide and bromide derivatives giving the best results. A likely mechanistic pathway involves the in situ generation of an aryne intermediate, and directing groups on the aryl ring inductively control regioselectivity.

Fe(NTms2)2 represents a novel cost-effective, environmentally benign catalyst for the hydrosilylation of carbonyl compounds at room temperature.

A series of silyl-terminated diynes of varying lengths and substitution patterns have been prepared. These diynes undergo zirconocene coupling with selective formation of trimeric macrocycles from linear alkynes, while nonlinear diynes give cyclodimeric products. The length of the linear diynes can be increased for the preparation of macrocycles with large nanoscale cavities. Reaction of the zirconium-containing macrocycles with acid results in the synthesis of metal-free cyclophanes. All of these macrocycles were prepared in multigram quantities, in the absence of high-dilution conditions, to give products in > 75% yield that are easily purified as crystalline solids.

A palladium-catalyzed, reductive homocoupling of haloenynes yields a diverse range of polysubstituted pentalene derivatives, including annulated dibenzopentalenes and dithienylpentalenes.

Zirconocene is the key: A new synthetic method, which utilizes zirconocene-mediated coupling of alkynes, has been developed for the preparation of a new class of highly Lewis acidic boroles (see scheme). Such compounds hold potential for applications in catalysis and the field of electron-deficient organic materials.

The synthesis, optical, electrochemical and physical characterization of 2,7-bis(pentafluorophenylethynyl)hexafluoroheterofluorenes is described along with a preliminary evaluation of their performance in photovoltaic applications.

The metal-mediated activation of carbon-hydrogen bonds has the potential of leading to important fundamental insights, as well as to advances in large-scale industrial and synthetic organic chemical processes. Our initialfinding of C-H oxidative addition reactions in low-valent iridium (I) complexes was followed by a more recent discovery and exploration of C-H activation processes at Ir (III) centers. This paper reviews recent studies of the Ir (III) reaction that include work directed toward elucidation of its reaction mechanism and the development of catalytic hydrogen/deuterium exchange reactions. The article also discusses collaborative studies of rhodium (I)-catalyzed reactions that provide a method for adding complexity to a range of carbo- and heterocyclic arene compounds with structures analogous to those found in physiologically active organic compounds.

A series of Pt complexes activated by Ag(I) salts have been shown to catalyze Markovnikov hydroarylations of unactivated olefins under mild conditions.