Carbon Dioxide → Ethyl 1-(2-acetoxyethyl)-4-chloropyrrole-2-glycolate

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Reaction Steps

A solution of water (25 ml.) in methanol (300 ml.) is cooled in a dry ice:carbon tetrachloride:acetone bath to -30° and 23.7 g. of sodium borohydride is added thereto. When the violent reaction has subsided, there is added, in a drop wise manner, 40 g. (0.139 mol.) of ethyl 1-(2-acetoxyethyl)-4-chloropyrrole-2-glyoxalate dissolved in methanol (400 ml.) at a rate such that the temperature does not exceed -20°. The reaction is maintained at this temperature for two hours when there is added a solution of 21.5 ml. of acetic acid in 320 ml. water. The solution is stirred for a further 1 hour at -30° during which time a white precipitate forms. This solid is collected by filtration and dissolved in dichloromethane. The organic solution was washed with saturated sodium chloride solution, dried over sodium sulphate and evaporated in vacuo. There is obtained 33.15 g. of a solid product which is homogeneous by thin layer chromatography. Recrystallization from dichloromethane-hexane yields ethyl 1-(2-acetoxyethyl)-4-chloropyrrole-2-glycolate, m.p. 60°-61° C. (Formula VI where Y is Cl).

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