Ethyl bromosuccinate

Problem 31.14 Ethyl bromosuccinate is converted into the unsaturated ester ethyl fumarate by the action of pyridine. What is the function of the pyridine What advantage does it have here over the usual alcoholic KOH ... 

A mixture of ethyl bromosuccinate and tinfoil in the presence of catalysts was stirred for 4 h, for example, and the tinfoil soon disappeared from the reaction mixture in the process. A product was easily isolated as a solid form from the reaction mixture, and two crystalline diastereomeric species were obtained by fractional crystallization of the above product. Based on the IR spectra of the products, the author first proposed a five-membered ring structure for organotin compounds in which lone electron pair of carbonyl oxygen coordinates to a tin atom, as shown in Eq. (2.4). 

In a similar reaction, bromosuccinic acid and thiobenzamide in ethyl-acetate yielded an acyclic intermediate (229), Ri = Ph, R2 = CH2C02H, which by heating in water cyclizes to the thiazole (230), Rj = Ph and R2 = CH2C02H. (260). 

Antoracemisation has been observed with substances not only in solid or liquid states but also in their solutions, For Example (+)-phenyl bromoacetic acid after three years of storage becomes inactive, in its solid state. A liquid showing antoracemisation is the ethyl ester of bromosuccinic acid. 

Comparison of bromofluorinations of six substituted ethyl cinnamates using A-bromosuccin-imide with hydrogen fluoride/pyridine and hydrogen fluoride/tetrahydrofuran (several molar ratios) also shows a Markovnikov-type regioselectivity. The stereoselectivity depends on several factors 184... 

A different approach using alkene derivatives involved allylic substitution reactions. Ethyl cyclohex-3-en-l-carboxylate (7.51) reacted with N-bromosuccin-imide to give 7.52.26 This allowed reaction with potassium phthalimide to give 7.53 in an overall yield of 41%. Catalytic hydrogenation and treatment with methylamine led to ds-3-aminocyclohexane-l-carboxylic acid, 7.22.26... 

CD-(4-Methoxyphenylthio)-4-bromoacetophenone refluxed with N-bromosuccin-imide in GGI4 cD-bromo-CD-(4-methoxyphenylthio)-4-bromoacetophenone (startg. m. f. 670) (Y 83%) refluxed 2 hrs. with the equimolar amount of ethyl thionocarbamate in acetone 4-(4-bromophenyl)-5-(4-methoxyphenylthio)-2-thiazolone (Y 81%). F. e. s. W. Groebel, B. 93, 896 (1960). 

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