Methyl-a-bromopropionate

Orsini and coworicers obtained primarily condensed ester from the reaction of methyl a-bromopropionate with zinc in a variety of solvents however, Johnson and Zitsman evidently obtained the reagent from ethyl a-bromopropionate in good yield by conducting the reaction at a lower temperature in ether (equation 3). 

Other studies of the Reformatsky reaction in refluxing benzene with ketone substrates are readily explained in terms of equilibrated zinc aldolates, although direct evidence for equilibration was not obtained. Matsumoto and coworkers examined the reaction of 3-phenyl-2-butanone with methyl a-bromopropionate and observed a net syn.anti ratio [(21 -i- 22) (23 -i- 24)] of 10 90, in harmony with equilibrated zinc aldolates (equation 34). 

The reaction of ethyl a-bromoacetate with 17-keto steroids such as estrone methyl ether or dehydroepiandrosterone acetate " under standard Reformatsky conditions is stereospecific, producing the 17 -ol in up to 80% yields. Ethyl a-bromopropionate reacts similarly but the yields are somewhat lower. 

Ethyl isocyanide, 46, 76, 77 Ethyl a-(isopropylideneaminooxy)pro-pionate, from acetone oxime and ethyl a-bromopropionate, 48,120 hydrolysis of, 48,121 Ethylmagnesium bromide, use with ferric chloride in cyclization of di-chloroacetone /J-Lolylmagncsium bromide adduct to l-f>-tolyicy-clopropanol, 47,108 Ethyl a-methyl-/3-phenylcinnamate, 48, 79... 

Methyl fi-bromopropionate has been prepared by the esterification of /3-bromopropionic acid with methyl alcohol alone1 and through the use of hydrogen bromide as a catalyst,2 and by the direct addition of hydrogen bromide to methyl acrylate.2... 

Ethyl N-benzylcarbamate, 35, 91 Ethyl 3-benzyl 2 cyano 3 methyl-pentanoate, 35, 7 Ethyl bromide, 34, 58, 36, 87 Ethyl a-bromobutyrate, 37, 44 Ethyl a bromopropionate, 35, 17, 37, 38... 

The method was originally proposed by Clemo and Metcalfe47 for the preparation of 3,5-dimethylpyrrolizidine. Condensation of ethyl (5-methyl-2-pyrrolidyl)acetate with ethyl a-bromopropionate resulted in the corresponding dicarboxylate (77), which was converted by cyclization and subsequent hydrolysis and decarboxylation into 3,5-... 

In another example of oxidation without fission, the major product obtained from the reaction of methyl 2-pyridylacetate with ethyl a-bromopropionate was not the expected indolizine (63) but its oxidation product (64). This was shown by a repetition of the reaction under nitrogen leading to (63), which subsequently could be oxidized to (64) by potassium ferricyanide (70JCS(C)1434). An oxidative dimerization at the 3-position of 1,2-dimethylin-dolizine was achieved with potassium ferricyanide (71TL1273) or palladium on charcoal in boiling xylene (81BCJ2833). 

A previous investigation indicated that the pyrolysis of methyl 3-bromopropionate alone was autocatalyzed by the HBr gas product. However, under maximum free-radical inhibition the reaction was homogeneous, unimolecular and of first order111. Moreover, the acidity of the hydrogen adjacent to the COOCH3 was held responsible for the faster... 

Using the lithium enolate of a-bromopropionate, trans and cis /V-(p-toluenesul-finyl)-2-methyl-2-carbomethoxy aziridines 191 were prepared from (S)-47.101-103 The -isomers predominate. Regio- and stereoselective aziridine ring-opening leads to efficient asymmetric syntheses of (-)-a-methylphenylalanine (192),102 (+)-a-methyl-p-phenylserine (193),102 (+)-2-methyl-3-phenylpropanoic acid (194a),103 and (-)-2-methyl-3-aminopentanoic acid (194b).103... 

Methyl /3-bromopropionate, 20, 64 Methyl carbitol, 22, 32 Methylcyclohexane, 21, 16 Methyl a,S-dibromopropionate, 20, 82 N-Methyl-3,4-dihydroxyphenylala-nine, 22, 89, 91, 93 Methyiethylethynyl carbinol, 20, 41... 

A mixture containing 3 ml of acetone, t-butylacrylate (80 mmol), and pentamethyl-diethylene-triamine (0.8 mmol) were added to CuBr (0.8 mmol) and CuBr2 (0.04 mmol). This mixture was then treated with methyl 2-bromopropionate (1.6 mmol) and heated for 6 hours at 60°C. It was cooled to ambient temperature and treated with 50 ml of acetone and neutral alumina. The acetone solution was concentrated and the residue purified by dissolving in diethyl ether. The purified material was precipitated in a methanol/water mixture, 1 1, at 0°C, dried, and the product was isolated having a M of 3000 daltons with a polydispersity index of 1.1. 

Under identical conditions, 31 is found to be stable, while 39 (R = H, X = Cl) is labile. This difference is probably due to the presence of the methyl on the imidazole ring. To test the effect of a methyl group present on the thiazole ring on the stability of bicyclic compound 45, the reaction of 28 with ethyl a-bromopropionate was carried out. Compound 46 was... 

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