Ketone n-alkyl methyl

Buu-Hoi has shown that n-alkyl methyl ketones excluding ethyl methyl ketone, yield primarily 2-monosubstituted cinchoninic acids. It has been demonstrated that the products of the condensation of isatin with aryloxyketones are the corresponding 3-aryloxy-4-quinoline carboxylic acids rather than the isomeric 2-aryloxymethylcinchoninic acids.In the case of simple a-alkoxyketones such as 1-alkoxyethyl methylketones, the preferred products are the 2-alkoxyalkylcinchoninic... 

Whereas cyclopropyl methyl ketone was hydrosilylated with an enantioselec-tivity of 81% ee, the increase of the steric demand of one of the alkyl groups led to improved enantiomeric excesses, reaching 95% ee in the case of terf-butyl methyl ketone. Linear-chain n-alkyl methyl ketones, which are particularly challenging substrates, were reduced with good asymmetric induction, such as in the case of 2-octanone (79% ee) and even 2-butanone (65% ee) [58]. 

A remarkably high diastereoselective excess was obtained in the addition of the anion of (S)-(-)-methyl 1-naphthyl sulfoxide to n-alkyl phenyl ketones. The sulfoxide was prepared in optically pure form by oxidation of the complex of methyl 1-naphthyl sulfide and 13-cyclodextrin with peracetic acid followed by crystallization. Desulfurization of the adducts provided enantiomerically pure tertiary alcohols (393]. 

Reaction Wave function Alkene, photocycloaddition, 366. 420-23 addition to benzene. 420 substituted, 432 Alkyl amines, tertiary. 466 Alkyl aryl ketones, 399, 402 Alkylethylenes, 420 Alkylidenecyclopropene. 57-58 N-Alkylimine, 375 Alkyl iodide, 471 Alkyl methyl ketones. 383-84 Alkyl radical, 380 Allene. 416 Ally radical. 102, 460 Allyl resonance, 461... 

SI) was more effective than 1-naphthylphenylsilane (S2). The R-absolute configuration of the product secondary alcohols was derived from the R-configura-tion of the 4 -position of the thiazolizine ring. Linear alkyl ketones, such as n-butyl methyl ketone, 2 -methylpropyl methyl ketone, were also reduced in 52.2% ee and 55.8% ee,respectively [14]. 

The usual selectivities are observed, with aryl alkyl ketones and alkyl methyl ketones being reduced with high enantioselectivity (1 -> 2 and 3 -> 4)). That 5 is reduced to 6 with high ee, with the reducing enzymes differentiating between an ethyl and an n-pentyl group, is even more impressive. 

The pyrrolidine enamines of /l -3.]cetosteroids (111), on alkylation with methyl iodide, gave mainly the N-alkylated product (5,55) in nonpolar solvents such as benzene. The reaction in more polar solvents gave the 4-methylated product (5.S). The reaction of (111) with perchloryl fluoride involves attack at the C-4 atom to give, after acid hydrolysis, either 4-fluoro-zJ -3-ketone (119) or 4,4-difluoro-zJ -3-ketone 120), depending on the reaction conditions (59). 

The alkylation of dienamines has not been studied extensively. Thus the dienamine (44) is reported (43,44) to alkylate at Cj with methyl iodide to give the iminium salt (45), which on hydrolysis gives the alkylated a,)3-unsatur-ated ketone (46). Similar dienamines prepared from A -2-oko steroids. On the other hand, are reported to undergo only N alkylation (45). 

Der Komplex aus Lithiumalanat, (-)- bzw. (+)-N-Methyl-ephedrin und 3,5-Dime-thyl-phenol reduziert unverzweigte Alkyl-aryl-ketone in Ausbeuten iiber 90% und optischen Ausbeuten von 62 bis 80% zu den (+)-(R)- bzw. (-) -(S)-1 -Phenyl-alka-nolen . 

Carbon disulphide methanol phenol n-hexane methyl n-butyl ketone organophosphorus compounds tetra-alkyl lead compounds. 

Hydrazones can also be deprotonated to give lithium salts that are reactive toward alkylation at the (3-carbon. Hydrazones are more stable than alkylimines and therefore have some advantages in synthesis.119 The A N-dimcthyl hydrazones of methyl ketones are kinetically deprotonated at the methyl group. This regioselectivity is independent... 

The metalation of vinyl ethers, the reaction of a-lithiated vinyl ethers obtained thereby with electrophiles and the subsequent hydrolysis represent a simple and efficient method for carbonyl umpolung. Thus, lithiated methyl vinyl ether 56 and ethyl vinyl ether 54, available by deprotonation with t- or n-butyllithium, readily react with aldehydes, ketones and alkyl halides. When the enol ether moiety of the adducts formed in this way is submitted to an acid hydrolysis, methyl ketones are obtained as shown in equations 72 and 73 . Thus, the lithiated ethers 56 and 54 function as an acetaldehyde d synthon 177. The reactivity of a-metalated vinyl ethers has been reviewed recently . 

Many organic chemicals are analyzed by RPC. These include various arylhydroxylamines as the N-hydroxyurea derivative with methyl isocyanate (614) alkyl- and alkoxy-disubstituted azoxybenzenes (6t5), n-alkyl-4-nitrophenylcarbonate esters ranging in length from methyl to octyl (616), 4-nitrophenol in the presence of 4-nitrophenyl phosphate (617), ben-zilic acid, and benactyzine-HCI using ion-pair chromatography (618), as well as aniline and its various metabolites (619), stereoisomers of 4,4 -dihydroxyhydrobenzoin (620), and aldehydes and ketones as the 2,4-dinitrophenylhydrazones (621). The technique has also been used to analyze propellants and hydrazine and 1,1-dimethylhydrazine were quantitita-vely determined (622, 623). 

The MacMillan laboratory has produced an interesting study on the reductive amination of a broad scope of aromatic and aliphatic methyl ketones catalyzed by ent-lk, utilizing Hantzsch ester as a hydride source (Scheme 5.26) [48]. Apphcation of corresponding ethyl ketones gave very low conversions. Computational studies indicated that while catalyst association with methyl ketones exposes the C=N Si face to hydride addition, substrates with larger alkyl groups are forced to adopt conformations where both enantiofaces of the iminium ir... 

Elsewhere, Heaney et al. (313-315) found that alkenyloximes (e.g., 285), may react in a number of ways including formation of cyclic nitrones by the 1,3-APT reaction (Scheme 1.60). The benzodiazepinone nitrones (286) formed by the intramolecular 1,3-APT will undergo an intermolecular dipolar cycloaddition reaction with an external dipolarophile to afford five,seven,six-membered tricyclic adducts (287). Alternatively, the oximes may equilibrate to the corresponding N—H nitrones (288) and undergo intramolecular cycloaddition with the alkenyl function to afford five,six,six-membered tricyclic isoxazolidine adducts (289, R = H see also Section 1.11.2). In the presence of an electron-deficient alkene such as methyl vinyl ketone, the nitrogen of oxime 285 may be alkylated via the acyclic version of the 1,3-APT reaction and thus afford the N-alkylated nitrone 290 and the corresponding adduct 291. In more recent work, they prepared the related pyrimidodiazepine N-oxides by oxime-alkene cyclization for subsequent cycloaddition reactions (316). Related nitrones have been prepared by a number of workers by the more familiar route of condensation with alkylhydroxylamines (Scheme 1.67, Section 1.11.3). 

Support-bound alkylating agents have been used to N-alkylate pyridines and dihydropyridines (Entries 7 and 8, Table 15.21). Similarly, resin-bound pyridines can be N-alkylated by treatment with a-halo ketones (DMF, 45 °C, 1 h [267]) or other alkylating agents [246]. Polystyrene-bound l-[(alkoxycarbonyl)methyl]pyridinium salts can be prepared by N-alkylating pyridine with immobilized haloacetates (Entry 8, Table 15.21). These pyridinium salts react with acceptor-substituted alkenes to yield cyclopropanes (Section 5.1.3.6). Pyridinium salts have also been prepared by reaction of resin-bound primary amines with /V-(2,4-dinitrophenyl)pyridinium salts [268,269]. 

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