Ethyl production

For example, ia the iadustriaHy important alkylation of benzene with ethylene to ethylbenzene, polyethylbenzenes are also produced. The overall formation of polysubstituted products is minimized by recycling the higher ethylation products for the ethylation of fresh benzene (14). By adding the calculated equiUbrium amount of polyethylbenzene to the benzene feed, a high conversion of ethylene to monoethylbenzene can be achieved (15) (see also... 

Vinylogous amides, which have an enamine function in conjugation with a carbonyl group, constitute tridentate systems and thus open the possibility of alkylation on carbon, nitrogen, or oxygen. It has been found that the pyrrolidine enamine of acetylacetone gives rise to a carbon mcthylation but an oxygen ethylation product 41). The alkylation of cyclic 1,3-diketone-derived enamines has been studied 41,283). O Alkylation was found in alcohol solvents and predominant C alkylation in nonprotonic solvents. 

The cyclization products can be ethylated using ethyl iodide with K2CO3 in DMF to give in the case of thiazolo[4,5-g]- or [4,5-/i]quinolones a mixture of O- and N-ethylated products, whereas in the case of thiazolo[5,4-g]- or -[5,4-/i] quinolones only A-ethyl products arise. Products of 0-ethylation were prepared by... 

An interesting extension of this reaction is shown in the asymmetric kinetic resolution of cyclic allylic ether 44 under alkene coupling conditions. Use of (R)-12 as the catalyst gives (R)-45 in > 99% ee at 58% conversion. The ethylated product 46 is also formed in the reaction in 94% ee (Eq. 7) [25]. The reaction is effective for six- to eight-membered 3-oxacycloalkenes 47 as well as for a wide variety of alkoxycycloalkenes 48 [27], with some resolution dependency on the ring size of 47 (Fig. 2) [26]. 

Figure 2. Solubilities and molecular weights of a vitrinite (80.8% C, daf) after nonreductive ethylation (yields calculated on ethylated product (daf))...

Nitrone (286) reacts readily with nucleophilic ethyl radicals to give the expected ethyl product (288) in 50% yield as the only diastereomer, as well as a 32% yield of the C,0 -diethyl product (289) and trace quantities of ethyl... 

The 80% yield represents the ethyl product from addition of Mel (ArLi - ArCH, —> ArCtLLi -> ArCtLCH,). 

The chiral, nonracemic, tricyclic dioxopiperazine derivative 1, easily obtained from proline, is transformed with sodium amide in liquid ammonia into its monoenolate, then alkylated with bromoethane to give the chiral, nonracemic ethylation product 2. On deprotonation and further alkylation. 2 furnishes the achiral fra/w-dialkylated product 3 in good yield1. 

It is difficult to explain the results of enantioselective alkylation of 2-methoxycarbonyl-l-oxoindane by a simple SN2 mechanism the yield of the 2-ethyl product is greater than that of the 2-methyl product, whereas the reverse was expected, and, in addition, the configurations of the two products are opposite. Thus, a mechanism has been proposed that involves either a sulfurane intermediate or a tight ion pair10. 

Natarajan, A.T., Simons, J.W.I.M., Vogel, E.W. van Zeeland, A.A. (1984) Relationship between cell killing, chromosomal aberrations, sister-chromatid exchanges and point mutations induced by monofunctional alkylating agents in Chinese hamster cells. A correlation with different ethylation products in DNA. Mutat. Res., 128, 31-40... 

Amplification of Chirality. Perhaps the most striking of the nonclas-sical aspects that emerge from the enantioselective alkylation is the phenomenon illustrated in Scheme 22 (3, 14, 16, 20k, 40). A prominent nonlinear relation that allows for catalytic chiral amplification exists between the enantiomeric purity of the chiral auxiliary and the enantiomeric purity of the methylation or ethylation product (Scheme 23). Typically, when benzaldehyde and diethylzinc react in the presence of 8 mol % of (-)-DAIB of only 15% ee [(-) (+) = 57.5 42.5], the S ethylation product is obtained in 95% ee. This enantiomeric excess is close to that obtained with enantiomerically pure (—)-DAIB (98%). Evidently, chiral and achiral catalyst systems compete in the same reaction. The extent of the chiral amplification is influenced by many factors including the concentration of dialkylzincs, benzaldehyde, and chiral... 

Whereas iV-tosylimines do not coordinate diethylzinc well in polar solvents (and thus tend to give ethylated product), solvents such as toluene favour coordination, leading to reduction of the imine to secondary amines under mild conditions, via a /3-hydrogen transfer mechanism 48... 

Regioselective cross-coupling of 5,7-dichloroquinolines with (l-ethoxyvinyl)tri( -butyl)stannane occurs at the 5-position in the presence of a neighboring tosylamide group to give the corresponding 5-acylquinoline 19 and also small amounts of iV-ethyl product 20 (Equation 11) <1997SL473>. 

Chelation-assisted C-H/olefin coupling can be applied to the atroposelective alkylation of biaryl compounds. The reaction of 2-(l-naphthyl)-3-methylpyri-dine with ethylene using [RhCl(coe)2]2 where coe is cyclooctene, and PCy3 results in the formation of an ethylation product in 92% yield (Eq. 21) [20]. In place of the PCy3 ligand, the use of (R) - (1 - [ (S) - 2- diphenylphosphino ] ferro-cenyl)ethyl methyl ether [(R),(S)-PPFOMe] leads to the atropselective alkyla-... 

The iV-alkylation was considered to occur by the reaction of the carbonyl compounds, formed by the dehydrogenation of alcohols over the catalyst, with the hydrogenation products of pyridine,25 as suggested by Schwoegler and Adkins, who obtained good yields of /V-alkylpiperidines by the reaction of piperidine with alcohols.26 Maruoka et al. obtained a higher maximal yield of the iV-ethylated product in ethanol over Raney Co than over Raney Ni in the hydrogenation of 5-ethyl-2-methylpyridine (eq. 12.16),23 an alkylated pyridine prepared industrially by the reaction of acetaldehyde with ammonia. 

Microwave irradiation of a mixture of cyclohexenones and ethyl acetoacetate adsorbed on the surface of solid lithium 5-(2)-prolinate leads to the stereoselective construction of bicyclo[2.2.2]octanone (69) systems through Michael addition and subsequent intramolecular aldolization (Ranu et al., 2000). Electron-rich aromatic compounds react with formaldehyde and a secondary amine under solvent-free condition and microwave irradiation in a microwave oven to produce amino ethylated products (70) in good to excellent yields (Mojtahedi et al., 2000). 

The product from Step 1 (1 eq) dissolved in ethyl alcohol was added to hydrazine hydrate (3 eq) and the mixture refluxed 12 hours. The mixture was cooled to ambient temperature and the crude product purified by re-crystallization in ethyl product. H-NMR data supplied. 

Rather low yields of ethylation products were obtained by reaction of 2,2,4-trimethylpentane with ethylene. It seems probable that the abstraction of hydrogen even from the tertiary carbon atom was difficult because it was a neohexyl carbon atom. It was suggested by gc and ms analysis that the major reaction did occur at the tertiary carbon atom, yielding... 

It may be concluded that primary alkyl chlorides undergo peroxide-induced, hydrogen chloride-promoted, alkylation with ethylene to yield products formed by alkylation at a tertiary carbon atom, at a penultimate secondary carbon atom, or at a primary carbon atom holding a chlorine atom. In the absence of hydrochloric acid, n-butyl chloride underwent little peroxide-induced reaction with ethylene presumably because hydrogen chloride is necessary for propagating the reaction chain via abstraction of hydrogen from the hydrogen chloride to produce the ethylated product and a chlorine atom which maintains the chain by abstraction from the alkyl chloride. 

The use of a formyl group as a directing functionality is challenging because, in the case of the low-valent transition metal-catalyzed reaction of aldehydes with an olefin, aldehydes are prone to undergo decarbonylation or hydroacylation of the olefins. The following protocol to suppress the decarbonylation, one being steric and the other electronic in nature, can be used. In the case of the reaction of 1-methylin-dole-3-carboxaldehyde with ethylene, the ethylation product is also obtained in quantitative yield (Eq. 9.5) [13]. 

A,A-dimethylhydrazones react with vinylsilane at the a-position. Zincated species are derived from dimethylhydrazones, vinylmagnesium bromide, and zinc bromide which afford a-ethylated products. If benzaldehyde is added before workup a net cinnamylation results. 

Bicyclopentane reacted with acetic acid at 86 °C to give acetoxycyclopentane (27 a, 47%) and cyclopentene (29a, 53%). In the presence of /7-toluenesulfonic acid a substantial amount of tosyloxycyclopentane was isolated. Deuterio- and methyl-substituted bicyclo[2.1.0]pentane derivatives were submitted to acid-catalyzed and uncatalyzed acetolysis reactions. The distribution of products was analyzed and the rates of reaction calculated. It was shown that the acetolysis of the extremely strained bicyclopentane proceeds mainly via inversion of configuration at both ends of the central bond when it was cleaved. 5,5-Dimethylbicyclo[2.1.0]pentane (31) reacted via cleavage of one of the outside C —C bonds, leading to 1-cyclobutyl-1-methyl-ethyl products 33, rather than via cleavage of the central bond. ... 

Diagram 24. M ethylation products of enteramine (5-hydroxytryptamine) occurring especially in amphibia. 

Katritzky and Harris reported in 1992 the use of diethylzinc for the chiral amino alcohol-mediated enantioselective addition to the C=N bond in these compounds (Scheme 12) [34]. These substrates act as masked activated N-acylimines. Of the large variety of Hgands available for the catalytic asymmetric reactions of dialkylzinc reagents,the sterically constrained P-dialkylamino alcohol, (-)-N,N-dibutylnorephedrine (DBNE) 18, prepared by alkylation of commercially available norephedrine, was selected for this study. Some preliminary experiments conducted with the use of -(aminobenzyl)benzotriazoles gave the ethylated product, but with no enantioselectivity. Diethylzinc (Et2Zn) was found to react even in the absence of a chiral promoter. The behavior of the less reactive N-(amidobenzyl)benzotriazoles 19a-g was then investigated. 

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