18-Crown-6 → [1-(2-Bromoethyl)-2-(phenylmethylene)hydrazino]oxoacetic acid, ethyl ester

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Reaction Steps

3.4 g. of the ethyl ester product from part (b) are dissolved in 100 ml. of acetone. 1.3 g. (50% excess) of lithium bromide and 0.1 g. of 18-Crown-6 (1,4,7,10,13,16-hexaoxacyclooctadecane) are added and the mixture is stirred for three hours at 50°. After the reaction has been completed as determined by TLC, the solvent is distilled off and the reaction mixture is taken up in 50 ml. of methylene chloride and shaken with 50 ml. of water. The organic phase is dried and concentrated to yield the crude product as an oil which, after scratching, crystallizes in several hours. Recrystallization from isopropanol yields purified [1-(2-bromoethyl)-2-(phenylmethylene)hydrazino]-oxoacetic acid, ethyl ester; m.p. 56°-57°.

Provenance & Evidence