Alkenes continued

Additions to the double bond of phospha-alkenes continue to be explored. The reactions of (177) with aliphatic diazo compounds... 

The protocol developed by Jacobsen and Katsuki for the salen-Mn catalyzed asymmetric epoxidation of unfunctionalized alkenes continues to dominate the field. The mechanism of the oxygen transfer has not yet been fully elucidated, although recent molecular orbital calculations based on density functional theory suggest a radical intermediate (2), whose stability and lifetime dictate the degree of cis/trans isomerization during the epoxidation <00AG(E)589>. 

Alkenes (continued) 476CM 660 (0.15) Trans (E) isomers have no unique... 

Cycloaddition reactions of pyrylium salts with alkenes continue to be explored in the context of natural products synthesis, as shown in Schemes 12-14. In the example shown in Scheme 12, a pyrylium-ylide [5+2] cycloaddition was performed (128—> 129), allowing access to intermediates reminiscent of the core framework of the diterpene antibiotic, guanacastepene <2001TL4947>. 

The field of homogeneous palladium catalysis traces its origin to the development of the Wacker process in the late 1950s (Eq. 7) [83]. Since this discovery, palladium-catalyzed reactions have evolved into some of the most versatile reactions for the synthesis of organic molecules [84,85]. Palladium-catalyzed Wacker-type oxidation of alkenes continues to be an active field of research [86-88], and several recent applications of NHC-coordinated Pd catalysts have been reported for such reactions. 

The regenerated bromine radical reacts with another molecule of the alkene, continuing the chain reaction. Both of the propagation steps are moderately exothermic, allowing them to proceed faster than the termination steps. Note that each propagation step starts with one free radical and ends with another free radical. The number of free radicals is constant, until the reactants are consumed, and free radicals come together and terminate the chain reaction. 

Similarly, in situ generation of N-vinyl-N-cyclohexylnitrosonium catirais and their 4 ir participation in regio- and stereo-specific [4 + 2] cycloaddition reactions with the full range of electron-rich, neutral and electrrai-deficient alkenes continue to be extensively investigated. 

Phospha-alkenes continue to attract the interest of the coordination chemists and yet another mode of coordination has been discovered.Oxidative addition of the halogen-phosphorus bond... 

Table 8 Addition of Kolbe Radicals to Alkenes (continued) ...

The reactions of phosphorus pentachloride (78) with electron-rich alkenes continue to be prominent in the Russian literature, and a few selected examples are given in Schemes 7 and 8. In the reaction of (78) with 2-methylpropene, the formation of... 

There is growing interest in the partial oxidation of the C5 fraction of the hydrocarbon stream from naphtha steam crackers since there is no real market for them at the present time. Furthermore, the partial oxidation of lower alkanes and alkenes continues to pose challenging problems for catalysis researchers. In the case of C5 hydrocarbon oxidation to form phthalic anhydride, the challenge is even greater since the catalyst needs not only to insert oxygen selectively, but also promote the formation of C-C bonds in an oxidative medium. In recent years, several studies have been reported in the literature, focusing on Cg oxidation using catalysts such as supported vanadia, VPO catalysts, and molybdates [1-11]. ... 

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