Getting the sterics just right: a five-coordinate iridium trisboryl complex that reacts with C-H bonds at room temperature

Five-coordinate boryl complexes relevant to Ir mediated C-H borylations have been synthesized, providing a glimpse of the most fundamental step in the catalytic cycle for the first time.

A general copper-catalyzed sulfonylation of arylboronic acids

A general copper-catalyzed method for the sulfonylation of arylboronic acids with sulfinate salts is described. A variety of alkyl-aryl, diaryl, and alkyl-heteroaryl sulfones were synthesized in good yield.

Development of a General and Efficient Iron-Catalyzed Epoxidation with Hydrogen Peroxide as Oxidant

The development of inexpensive and practical iron catalysts for the environmentally benign epoxidation of olefins with hydrogen peroxide as terminal oxidant is described. By systematic variation of ligands, metal sources, and reaction conditions, it was discovered that FeCl3 x 6 H2O in combination with pyridine-2,6-dicarboxylic acid and different amines shows high reactivity and excellent selectivity towards the epoxidation of aromatic olefins and moderate reactivity towards that of aliphatic olefins.

A Novel Environmentally Benign Method for the Selective Oxidation of Alcohols to Aldehydes and Ketones

In the presence of [Ru(terpyridine)(2,6-pyridinedicarboxylate)], aliphatic and benzylic alcohols are oxidized to the corresponding aldehydes or ketones with high selectivity by using hydrogen peroxide as the oxidant. There is no need for the addition of co-catalysts or organic solvents. By applying an optimized reaction protocol, high catalyst productivity (turnover number>10,000) and activity (turnover frequency up to 14,800 h(-1)) has been achieved.

An efficient biomimetic Fe-catalyzed epoxidation of olefins using hydrogen peroxide

A new, environmentally benign and practical epoxidation method was developed using inexpensive and efficient Fe catalysts. FeCl3.6H2O in combination with commercially available pyridine-2,6-dicarboxylic acid and amines showed excellent reactivity and selectivity towards aromatic olefins and moderate reactivity towards 1,3-cyclooctadiene utilizing H2O2 as the terminal oxidant.

New Synthetic Protocols for the Preparation of Unsymmetrical Bisindoles

Novel unsymmetrical bisindoles were synthesized by a solvent-free C-C bond-formation reaction under mild conditions. Starting from aziridines or hydroxyl precursors, indoles have been used as C-nucleophiles to form new pharmacologically interesting bisindoles via an electrophilic aromatic substitution pathway in good to excellent yields. [reaction: see text]

Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2, Part I: Synthesis of New ChiralN,N,N-Tridentate Pybox and Pyboxazine Ligands and Their Ruthenium Complexes

The synthesis of chiral tridentate N,N,N-pyridine-2,6-bisoxazolines 3 (pybox ligands) and N,N,N-pyridine-2,6-bisoxazines 4 (pyboxazine ligands) is described in detail. These novel ligands constitute a useful toolbox for the application in asymmetric catalysis. Compounds 3 and 4 are conveniently prepared by cyclization of enantiomerically pure alpha- or beta-amino alcohols with dimethyl pyridine-2,6-dicarboximidate. The corresponding ruthenium complexes are efficient asymmetric epoxidation catalysts and have been prepared in good yield and fully characterized by spectroscopic means. Four of these ruthenium complexes have been characterized by X-ray crystallography. For the first time the molecular structure of a pyboxazine complex [2,6-bis-[(4S)-4-phenyl-5,6-dihydro-4H-[1,3]oxazinyl]pyridine](pyridine-2,6-dicarboxylate)ruthenium (S)-2 aa, is presented.

Ruthenium-Catalyzed Asymmetric Epoxidation of Olefins Using H2O2, Part II: Catalytic Activities and Mechanism

Asymmetric epoxidation of olefins with 30 % H2O2 in the presence of [Ru(pybox)(pydic)] 1 and [Ru(pyboxazine)(pydic)] 2 has been studied in detail (pybox = pyridine-2,6-bisoxazoline, pyboxazine = pyridine-2,6-bisoxazine, pydic = 2,6-pyridinedicarboxylate). 35 Ruthenium complexes with sterically and electronically different substituents have been tested in environmentally benign epoxidation reactions. Mono-, 1,1-di-, cis- and trans-1,2-di-, tri-, and tetra-substituted aromatic olefins with versatile functional groups can be epoxidized with this type of catalyst in good to excellent yields (up to 100 %) with moderate to good enantioselectivies (up to 84 % ee). Additive and solvent effects as well as the relative rate of reaction with different catalysts have been established. It is shown that the presence of weak organic acids or an electron-withdrawing group on the catalyst increases the reactivity. New insights on the reaction intermediates and reaction pathway of the ruthenium-catalyzed epoxidation are proposed on the basis of density functional theory calculation and experiments.

Synthesis of a New Chiral N,N,N-Tridentate Pyridinebisimidazoline Ligand Library and Its Application in Ru-Catalyzed Asymmetric Epoxidation

A small ligand library of chiral tridentate N,N,N-pyridinebisimidazolines have been synthesized for the first time. This new class of ligands can be easily tuned and synthesized on multi g-scale. The usefulness of the ligands is shown in the ruthenium-catalyzed asymmetric epoxidation with hydrogen peroxide as oxidant. Excellent yields (>99%) and good enantioselectivities (up to 71% ee) have been obtained for the epoxidation of aromatic olefins. [reaction: see text]

Convenient Method for Epoxidation of Alkenes Using Aqueous Hydrogen Peroxide

[reaction: see text] The complex [Ru(tpy)(pydic)] (1a) is an active catalyst for epoxidation of alkenes by aqueous 30% hydrogen peroxide in tertiary alcohols. The protocol is simple to operate and gives the corresponding epoxides in good to excellent yields. Chiral enantiopure [Ru(tpy)(pydic)] complexes have been synthesized and successfully applied in this procedure.

Remarkably selective iridium catalysts for the elaboration of aromatic C-H bonds

Arylboron compounds have intriguing properties and are important building blocks for chemical synthesis. A family of Ir catalysts now enables the direct synthesis of arylboron compounds from aromatic hydrocarbons and boranes under "solventless" conditions. The Ir catalysts are highly selective for C-H activation and do not interfere with subsequent in situ transformations, including Pd-mediated cross-couplings with aryl halides. By virtue of their favorable activities and exceptional selectivities, these Ir catalysts impart the synthetic versatility of arylboron reagents to C-H bonds in aromatic and heteroaromatic hydrocarbons.

Regioselective aromatic borylation in an inert solvent

[reaction: see text]. A protocol for performing Rh catalyzed aromatic borylations in cyclohexane has been devised. Borylation at the 5-position of several 1,3-substituted aromatic species ranging from electron-rich (1,3-(NMe(2))(2)C(6)H(4)) to electron-deficient (1,3-(CF(3))(2)C(6)H(4)) yields the corresponding aryl boronate esters. Veratrole was selectively borylated at the 4-position, thus extending regioselectivity to 1,2-substituted benzenes. Selective borylation at the 3-position of an N-protected pyrrole has also been demonstrated, providing a valuable reagent for cross-coupling reactions in a single step.

Monitoring the integrity of the cement-metal interface of total joint components in vitro using acoustic emission and ultrasound

Debonding of the cement-metal interface of cemented femoral components of total hip arthroplasty has been shown from clinical and autopsy material to be a common occurrence. Experimentally, debonding has been shown to increase markedly the strains in the adjacent cement mantle. Studies of autopsy-retrieved specimens demonstrate that debonding of the cement-metal interface is a key initiating event in loosening of cemented femoral components of total hip arthroplasty. However, both the radiographic and autopsy evidence of cement-metal interfacial debonding exist after the fact, that is, after debonding has occurred. The lack of prospective data showing that debonding does indeed occur under physiologic loading and occurs prior to other forms of failure of fixation leaves uncertain the issue of debonding and its role in initiating loosening of cemented femoral components. Knowing when, where, and to what extent the cement-metal interface debonds is critical information in understanding the process of loosening of cemented femoral components. Such information would contribute to improving the durability of stems and improving cementing techniques. In this study, the two nondestructive techniques of acoustic emission and ultrasonic evaluation of the cement-metal interface of cemented femoral stems of total hip arthroplasty were combined to investigate when, where, and to what extent cement-metal debonding occurred in vitro in simulated femurs loaded physiologically in fatigue in simulated single-leg stance. Debonding of the cement-metal interface of a cemented femoral component in this model was both an initiating event and a major mechanism of compromise of the cement-metal interface. Additional acoustic emission signals arose from cracks that developed in the cement.

Synthesis of beta-Mono-, Tetra-, and Octasubstituted Sterically Bulky Porphyrins via Suzuki Cross Coupling

beta-Mono-, tetra-, and octasubstituted tetramesitylporphyrins were prepared in good yields by Suzuki cross-coupling reactions of beta-bromotetramesitylporphyrins with aryl- and alkylboronic acids.

In vitro evaluation of bonding of the cement-metal interface of a total hip femoral component using ultrasound

Debonding of the cement-metal interface of a cemented femoral component is one mechanism associated with loosening of total hip replacement. An ultrasonic pulse-echo technique was developed to determine, nondestructively, the integrity of the cement-metal interface in vitro. The characteristics of the ultrasonic reflections of bonded and debonded interfaces were obtained by using a physical model that consisted of a flat slab of cement and a flat cobalt alloy plate with known conditions of bonded and debonded interfaces. The same model was used to establish that the ultrasonic technique could distinguish between two surfaces that were in direct opposition but not bonded and those that were actually bonded. This technique then was shown to be useful in nondestructively detecting bonded and debonded cement-metal interfaces of femoral prostheses cemented into fiberglass femurs and femurs from human cadavera.

Fine needle aspiration diagnosis of angiomyolipoma of the liver using a cell block with immunohistochemical study. A case report

Fine needle aspiration diagnosis of hepatic angiomyolipoma has been reported rarely. Below we report one such case diagnosed by examination of a cell block. The presence of epithelioid smooth muscle cells, mature adipocytes, thick-walled vessels and extramedullary hematopoiesis established the diagnosis. It was further substantiated by positive staining of the epithelioid cells for muscle-specific actin (HHF-35). The epithelioid cells were also immunoreactive with a melanocytic marker, HMB-45, but not with desmin, vimentin, cytokeratin or S-100 protein. HMB-45 might prove to be a sensitive marker for the epithelioid smooth muscle component of the tumor. The advantage of the routine use of a cell block in fine needle aspiration is emphasized.