Methyl 1-bromoethyl ketone

Treatment of 1-bromoadamantane with AlBr3 in the presence of ethylene at -75 °C to give l-(j3-bromoethyl)-adamantane 202) followed by reduction 20°) results in good yields of 1-ethyladamantane (Eq. (63)). Wolf-Kishner 164) or Clemensen 203) reduction of commercially available methyl adamantyl ketone provides an alternative route for the preparation of this compound. 

The direct bromination of aliphatic ketones occurs readily, often giving isomeric mixtures. Thus, methyl ethyl ketone and an equimolar quantity of bromine yield the a-btomomethyl (17%) and the a-bromoethyl (50%) isomers polybrominated products are also formed. On the other hand, only the tertiary hydrogen in methyl isopropyl ketone is substituted upon monobromination. By varying the conditions for the bromination of acetone, mono- or poly-substitution products may be formed e.g., bromo-acetone (44%), a,a -dibromoacetone (60%), and a,a,a -tribromoacetone (60%). ... 

Bromoethyl methacrylate Single Tgi transparency Miscible when cast from methyl ethyl ketone immiscible en cast from tetrahydrofuran Neo and Goh (1992a)... 

A general methodology for the construction of quaternary carbon atoms at the carbonyl carbon of ketones has been successfully exploited for the facile synthesis of ( )-lycoramine (299) (Scheme 30) (165). Thus, the O-allylated o-vanillin 322 was allowed to react with vinyl magnesium bromide followed by Jones oxidation, and the acid-catalyzed addition of benzyl IV-methylcarbamate to the intermediate a,(3-unsaturated ketone furnished 323. Wadsworth-Emmons olefination of 323 with the anion derived from diethyl[(benzylideneami-no)methyl]phosphonate (BAMP) provided the 2-azadiene 324. The subsequent regioselective addition of n-butyllithium to 324 delivered a metalloenamine that suffered alkylation with 2-(2-bromoethyl)-2-methyl-l,3-dioxolane to give, after acid-catalyzed hydrolysis of the imine and ketal moieties, the 8-keto aldehyde 325. Base-catalyzed cycloaldolization and dehydration of 325 then provided the 4,4-disubstituted cyclohexenone 326. The entire sequence of reactions involved in the conversion of 323 to 326 proceeded in very good overall yield and in one pot. 

An improved route to the key intermediate 326 was also developed (165). Namely, 322 was converted to the monoprotected 1,4-dione 327 by sequential addition of the Grignard reagent derived from 2-(2-bromoethyl)-2-methyl-l,3-dioxolane followed by oxidation of the resulting benzylic alcohol with pyridin-ium dichromate (PDC). The ketone 327 was then smoothly transformed to the 2-azadiene 328 by olefination with BAMP. The regioselective addition of n-butyllithium to 328 as before followed by alkylation of the resulting metalloenamine with benzyl A-(2-bromoethyl)-A-methylcarbamate and acid-catalyzed hydrolysis furnished 325, which was converted to the cyclohexenone 326 by base-induced cycloaldolization and dehydration. 

Use of Ci-bromoethyl methyl ketone as alkylating agent for malonic ester gives a 74% yield of ethyl a-carbethoxy-y0-methyllevulinate. The second a-hydrogen atom may be replaced by a methyl group in 76% yield. The keto acids, /3-methyllevulinic acid (40%) and a,/8-dimethyllevulinic acid (83%), are then obtained by decarboxylation of the dibasic acids at 140° and 120°, respectively. ... 

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