Ethyl 5-bromovalerate

Sodium hydride, 50% dispersion in mineral oil Alpha Inorganics Ethyl 5-bromovalerate A... 

A reactor was charged with polyethylene glycol (0.5 mol M 10,000), and treated with 50 ml of toluene, and azeotropically dried by refluxing for 2 hours. The resulting mixture was dissolved in 30 ml of THF and treated dropwise with sodium hydride (5 mmol) dissolved in 20 ml of THF and refluxed overnight. This mixture was then treated with ethyl-5-bromovalerate (5 mmol) and refluxed overnight and concentrated. The residue was precipitated by the addition of 2-propanol/diethyl ether, 1 1, and then fdtered to yield 4.5 g of isolated product. 

Ethyl 5-bromovalerate Pentanoic acid. 5-bromo-, ethyl ester (14660-52-7), 76, 255... 

Continuing their rational design, Jiracek and al. described a-aminophosphinic acids 239, 240, structurally close to compounds 235 and 237 [161]. Each structure was obtained in 56-64% yield, by mixing ethyl 5-bromovalerate or ethyl 5-bromo-3,3-dimethylpentanoate with phosphinomethionine 238 in the presence of sodium and ammonia (Scheme 46). The //-phosphinic acid intermediate 238 was readily accessible by a sequence of three steps from acrolein [162-164]. 

C2H5I + Na2Fe(CO)4 + BrECHJ COOCaHs -> C H COICH COOC H Ethyl 5-bromovalerate added under Ng to a soln. of Na-tetracarbonylferrate(-II) in N-methyl-2-pyrrolidone, stirred 1 hr., ethyl iodide added, and the product isolated after 24 hrs. ethyl 6-ketooctanoate. Y 74%. - The most remarkable feature of the above reagent is its toleration of functional groups. F. e., also with tosylates, whidi minimize eliminations, s. J. P. Collman, S. R. Winter, and D. R. Clark, Am. Soc. 94, 1788 (1972). 

In addition, it has been shown that nucleophilic substitution reactions of mPEG-alk-oxides with ethyl 5-bromovalerate and ethyl 4-bromo-4-methyl butyrate, yield mPEG-ethyl valerate and mPEG-ethyl 2-methyl butyrate respectively, which upon hydrolysis should afford the corresponding free acids [81,82]. Presumably these reactions also give elimination products, as indicated for ethyl 3-bromopropionate. 

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