Toluene with cyclooctene

In batch, this catalyst system (1 mol%) will convert cyclooctene in a two-phase toluene-water system at 60°C to the epoxide in 87% yield after 90 minutes and in 99% yield after 160 min (Scheme 4.2). The nature of the PTC is extremely important best results were obtained with MeN0ct3HS04. 

Gold-catalyzed oxidation of styrene was firstly reported by Choudhary and coworkers for Au NPs supported on metal oxides in the presence of an excess amount of radical initiator, t-butyl hydroperoxide (TBHP), to afford styrene oxide, while benzaldehyde and benzoic acid were formed in the presence of supports without Au NPs [199]. Subsequently, Hutchings and coworkers demonstrated the selective oxidation of cyclohexene over Au/C with a catalytic amount of TBHP to yield cyclohexene oxide with a selectivity of 50% and cyclohexenone (26%) as a by-product [2]. Product selectivity was significantly changed by solvents. Cyclohexene oxide was obtained as a major product with a selectivity of 50% in 1,2,3,5-tetramethylbenzene while cyclohexenone and cyclohexenol were formed with selectivities of 35 and 25%, respectively, in toluene. A promoting effect of Bi addition to Au was also reported for the epoxidation of cyclooctene under solvent-free conditions. 

Enantioselective Hydrogenation. (R,5 )-CAMPHOS has been employed in combination with rhodium(I) to reduce alkene carbon-carbon double bonds. Thus, the Rh(I) complex formed from (R,5 )-CAMPHOS and [Rh(cyclooctene)2Cl]2 in toluene-EtOH-EtsN solution catalyzes the hydrogenation (1 atm H2, 20 °C) of atropic acid and of ct-acetamidocinnamic acid. The... 

A methodically related transformation, the copper(Il)-mediated transfer of a cyano(ethoxycar-bonyl)methylene unit from ethyl cyanoacetate to alkenes, is presented in Section I.2.I.2.4.2.9. The copper-mediated synthesis of cyclopropyl ketones from a,a-dibromo ketones and alkenes seems to be of very limited scope and even less efficient than the corresponding synthesis of cyclopropanecarboxylic acids from o ,a-dibromoacetates (vide supra). The reaction (toluene, 100°C, 93 h) of cyclooctene (4.0 mmol), dibromomethyl phenyl ketone (8.0mmol), and commercial grade copper powder (18 mmol) activated with iodine (0.2 mmol) gave exy-9-benzoyl-bicyclo[6.1.0]nonane (7, 12%) and (2-oxo-2-phenylethyl)cyclooct-l-ene (8, 3%). ° A similar treatment of styrene gave l-benzoyl-2-phenylcyclopropane in only 2% yield [ratio (cisjtrans) 1 l.b]. " ... 

FIGURE 16.2 Conversion versus time for the epoxidation of cyclooctene catalyzed by various W-based catalyst systems (0.1 mol% W) at 60 °C in toluene in the presence of 1.5 equiv 50% H2O2. Reprinted with permission from [10]. Copyright 2004 American Chemical Society. 

For instance, the reaction of EtaSiH and 2 equiv. of p-methoxystyrene in toluene with 1.0 mol% of 16a afforded at 100°C within 6 h the dehydrogenative silylation product ( )-l-(p-methoxystyryl)-2-(triethyl-silyl)ethylene in 95% yield. The reaction is of high selectivity that neither (Z)-isomers, nor branched dehydrogenative silylation products were seen. Less hydridic silanes, such as triphenylsilane, were less efficient than for instance EtsSiH. Other substituted styrenes such as p-methyl, p-chloro-, and p-fluorostyrene also afforded the corresponding tran -vinylsilanes in high yields and selectivities (up to 98%). In the case of aliphatic alkenes, such as -octene, allyltriethoxysilane, vinylcyclohexane, and ethylene, dehydrogenative silylations were still preferred, but showed less E/Z selectivity. Cyclic olefins, such as cyclooctene, furnished low conversions under the same reaction crmditions. The results are summarized in Scheme 19. 

Different nanocrystals shapes are obtained by variation of the organic stabilizer type and its concentration. For instance, if organometallic compounds such as nickel bis-cyclooctene-l,5-diene(Ni(COD)2) are subjected to the heat treatment and decomposition in the presence of hexadecylamine (GDA) or trioctylphosphenoxide, the nanorods or nanospheres can be obtained [311]. The particles of bracelet shape and 27 nm size have been synthesized in Ref. [312]. The tetrahedral structures [313] have been obtained when the cobalt nanoclusters react with NaAOT/toluene at 130 °C. 

These complexes showed higher thermal stabihty in toluene at 80 °C than the Hoveyda first-generation catalyst, with half-lives ranging from 3 to 6 h, depending on the nature of the Schiff base-derived hgand. They also showed latent catalyst behavior, as only moderate-to-low olefin metathesis activity was observed at room temperature in CM and RCM [44]. On the other hand, these complexes were active in the ROMP of cyclooctene and cyclopentene. The NHC-containing catalyst was found to be especially efficient, leading to a TOP of 667 min at room temperature [43]. 

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