A new PCP-type ligand based on an N-heterocyclic olefin (NHO) scaffold has been prepared. The flexibility of this ligand, which is able to adopt facial coordination modes in Ir(I) or meridional in Ir(III) complexes, can be attributed to the dual nature (ylide-olefin) of the NHO scaffold. This results in a rare case of olefin "slippage" that is supported by X-ray crystallography and DFT calculat...

Chelated ruthenium catalysts have achieved highly chemoselective olefin metathesis reactions. Terminal and internal Z olefins were selectively reacted in the presence of internal E olefins. Products were produced in good yield and high stereoselectivity for formation of a new Z olefin. No products of metathesis with the internal E olefin were observed. Chemoselectivity for terminal olefins was ...

In this study we have investigated computationally the origin of the cis-trans selectivity in the Ru-catalyzed cross metathesis (CM) of a prototype monosubstituted olefin, i.e., propene. Our calculations suggest that the origin of the preferential formation of trans-olefins is in the product release step, which prevents the initially formed cis-olefin from escaping the metal, and returns it to ...

Complexes of the type [Cu(H-dpa)(olefin)]BF4 for ethylene (1), propylene (2), 1-butene (3), 1-hexene (4), 1-octene (5), cis-2-octene (6), trans-2-octene (7), cis-3-octene (8), trans-3-octene (9), 2-norbornylene (10), 1,5-cyclooctadiene (11), styrene (12), cis-stilbene (13), trans-stilbene (14), and Ph2C=CH2 (15) have been prepared and characterized by 1H and 13C NMR, FTIR, and TGA. The crystal ...

A tandem olefin metathesis/oxidative cyclization has been developed to synthesize 2,5-disubstituted tetrahydrofuran (THF) diols in a stereocontrolled fashion from simple olefin precursors. The ruthenium metathesis catalyst is converted into an oxidation catalyst in the second step and is thus responsible for both catalytic steps. The stereochemistry of the 1,5-diene intermediate can be controll...

[reaction: see text]Transannular macrocyclizations via intramolecular B-alkyl Suzuki reactions are described. Regioselective terminal olefin hydroboration with 9-BBN followed by Pd(0)-catalyzed Suzuki reaction in the presence of a base such as TlOEt at high dilution generates macrocycles with a high degree of control over olefin geometry with isomerically pure E or Z vinyl iodide substrates. Th...

The design and preliminary laboratory testing of a prototype portable instrument capable of near-real-time measurement of selected airborne olefins and dienes at lowand sub-ppm concentrations is described. The sensor employed is a 60-MHz surface-acoustic-wave (SAW) oscillator coated with a Pt-olefin coordination compound having the formula trans-PtC12(olefin)(pyridine) (olefin= 1-hexene or ethy...

The literature of olefin metathesis by heterogeneous supported catalysts, both industrial-type supported metal oxides (ReOx/Al2O3, ReOx/(SiO2−Al2O3), MoOx/SiO2, MoOx/Al2O3, MoOx/(SiO2−Al2O3), WOx/SiO2, and WOx/ (SiO2−Al2O3)) and supported organometallic complexes, is comprehensively reviewed. The focus of this Review is supported metal oxide catalysts, but the well-defined supported organometal...

Macrocyclic compounds occupy an important chemical space between small molecules and biologics and are prevalent in many natural products and pharmaceuticals. The growing interest in macrocycles has been fueled, in part, by the design of novel synthetic methods to these compounds. One appealing strategy is ring-closing metathesis (RCM) that seeks to construct macrocycles from acyclic diene prec...