Reformatsky

CH2Br COOH. White crystalline solid, m.p. 50"C, b.p. 208 C. Soluble in water and alcohol. Prepared by the action of dry bromine on dry ethanoic acid in presence of small amounts of red phosphorus. Produces sores upon the skin used in chemical syntheses. See Reformatski reaction. 

Reformatski reaction Aldehydes and ketones react with a-bromo- fatty acid esters in the presence of zinc powder to give -hydroxy-esters which may be dehydrated to give a-, 0-unsaturated esters. a-Chloroesters will react if copper powder is used in conjunction with the zinc. 

The Reformatsky Reaction consists of the interaction of an ester of an a-halogeno-acid with an aldehyde, a ketone or another ester in the presence of zinc. For example, if a mixture of ethyl bromoacetate and benzaldehyde is heated with zinc, the latter undoubtedly first combines with the ethyl bromoacetate to form a Grignard-like reagent (reaction A), which then adds on to the benzaldehyde Just as a Grignard reagent would do (reaction B). The complex so formed, on acidification gives ethyl p-phenyl-p-hydroxy-propionate (reaction C). Note that reaction A could not satisfactorily be carried out using... 

This preparation illustrates the Reformatsky reaction, which consists in the interaction of a carbonyl compound, an a-halogen ester (e.g., ethyl bromo-acetate) and zinc In the presence of ether or benzene, followed by hydrolysis. 

This compound permits the introduction (in moderate yield) of a four carbon atom chain at the site of the carbonyl group by the use of the Reformatsky reaction (compare Section VI,8) ... 

Synthesis Control will be needed in the condensation as the ketone C is more reacfiye than the acid D both in enolisation and electrophilic power. The Reformatsky looks a good method. Again we don t know how this commercial product is actually made ... 

By analogy with the Reformatsky reaction, the zinc derivative of a p-bromoester would do ... 

Knoevenagel, Dieckmann, Stobbe, and Reformatsky reactions to name just a few. 

The reactions of ketenes or ketene equivalents with imines, discussed above, all involve the imine acting as nucleophile. Azetidin-2-ones can also be produced by nucleophilic attack of enolate anions derived from the acetic acid derivative on the electrophilic carbon of the imine followed by cyclization. The reaction of Reformatsky reagents, for example... 

Beckmann rearrangement, 3, 710 Pyran-4-carbaldehyde, 2,2-dimethyl-tetrahydro-Reformatsky reaction, 3, 732 4H-Pyran-4-carbaldehydes synthesis, 3, 760-761 Pyran-2-carbonitrile, 5,6-dihydro-reactions, 3, 732... 

REFORMATSKY BLAISE Zincahyiallon Synthesis of -hydrexyesters from cartxinyl derivatives arxl a-haloesters via a zmc reagent (Reformatsky). Synthesis ol eloesleis from nitriles and a-haloesters via a zinc reagent (QIaise). 

Reformatsky reaction. Similar R2CU R2Cd R2CuLi... 

Reformatsky reaction is the formation of p-hydroxyesters by reaction of a-bromoacid ester and a carbonyl compound, usually in the presence of zinc... 

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. 

Conversion of androstans to pregnanes via the Reformatsky Reaction 17a-pregn-5-ene-3/3,17/3,21-triol and ethyl 3/3-acetoxy-17/3-hy droxy-17a-pregn-5-en-21-oate, 139... 

Rearrangement of a,/B-epoxy ketones to ftdicarbonyl isomers, 307 Reductive alkylation, 97 Reductive cleavage of halo ethers, 264 Reductive degradation of 19-substitutional steroids, 277, 278 Reformatsky reaction, 139 Removal of the C-10 substituent in steroids. 272... 

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