Olefins, activated novel

As well as the above-mentioned activated olefins, many novel activated alkenes (Figure 1.2) have been developed in recent years, including [a-(ethoxy-carbonyl)vinyl]aluminum 88, ° chiral acryloylhydrazide 89, a,)S-unsaturated thiol esters 90, uridine derivatives 91, l-benzopyran-4(4//)-one derivatives... 

C) for a short time (less than 0.5 second). The higher catalyst temperature and shorter residence time of the SCTFR relative to that of a traditional riser reactor increase the fuel-oil conversion at the same coke yield and reduce hydrogen-transfer activity while increasing the yield of light olefins. This novel reactor configuration is expected to find important commercial applications. 

Anderson, .D., Baizer,M.M. Intramolecular electrolytic reductive coupling of activated olefins A novel route to cyclic compound. Tetrahedron Liters 1966(5), 511. 

Formyl carbene is preparable by a copper acetylacetonate-catalyzed decomposition of diazoacetaldehyde40. This new carbenoid species formed a cyclopropane-carboxaldehyde with a substituted olefin. A novel approach to 3-lactones of above 70% optical purity involves reaction of a carbonyl compound with a ketene (or with an acyl halide convertible to a ketene) in the presence of an optically active bose. Trichloroacetaldehyde reacts with ketene in the presence of brucine to form (+)-8 in the presence of (-)-l-phenyl-l-dimethylaminoethane, (-)-8 is formed. ... 

Allison, M. and Bennet, A., Novel, Highly Active Iron and Cobalt Catalysts for Olefin Polymerization, CHEMTECH, July, 1999, pp. 24-28. 

The outstanding performances of five-membered NHC ligands in organometallic chemistry and catalysis prompted Grubbs and co-workers to develop a novel stable four-membered NHC [64]. Following their interest in developing new ruthenium olefin metathesis catalysts, they synthesised and fully characterised complex 51 to study the impact of the architecturally unique NHC ligand on the activity of the Ru-based catalyst [65] (Fig. 3.20). In the RCM of 1 at 40°C in CH Cl with 51 (5 mol% catalyst), the reaction reached completion within 20 min, whereas less than 10 min are required for standard catalysts 14 and 16. It should be noted that catalysts 14 and 16 are able to complete the RCM of 1 with only 1 mol% catalyst at 30°C. 

A few further general examples of zinc catalytic activity or reactivity include the following. Other zinc-containing systems include a zinc phenoxide/nickel(0) catalytic system that can be used to carry out the chemo- and regioselective cyclotrimerization of monoynes.934 Zinc homoenolates have been used as novel nucleophiles in acylation and addition reactions and shown to have general utility.935,936 Iron/zinc species have been used in the oxidation of hydrocarbons, and the selectivity and conditions examined.362 There are implications for the mechanism of metal-catalyzed iodosylbenzene reactions with olefins from the observation that zinc triflate and a dizinc complex catalyze these reactions.937... 

Mimoun and coworkersdescribed the first well-defined example of a d° metal aUtylperoxidic species 49 which epoxidized simple olefins with high selectivity. Several features of the epoxidation performed by 49 resemble those of the Halcon catalytic epoxidation process " . Novel tungsten complexes containing 2 -pyridyl alcoholate ligands like 50 have been synthesized and tested as catalysts in the epoxidation of cw-cyclooctene with TBHP in the absence of solvent . The system displayed modest catalytic activity (100% conversion in 60 h) but excellent product selectivity. 

Kita has introduced a novel one-pot preparation of 5-methoxylated indoline 55 and indole 56 derivatives by intermolecular addition followed by cyclization between A-tosylaniline derivatives 53 and activated olefins 54 using phenyliodine(III) bis(trifluoroacetate) (FIFA) <99H511785>. In the reaction of 53 with phenyl vinyl sulfides, indoles were produced directly by the spontaneous elimination of thiophenol. 

Oxidation of Styrene. Until now we have considered only olefins which have allylic hydrogen available for radical abstraction. Most of the evidence in these systems suggests the formation of allylic hydroperoxides and their subsequent reaction to form stable oxidation products in the presence of various transition metal complexes. It has not been necessary to postulate novel catalytic activation of oxygen to explain our... 

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