PURPOSE: To obtain the titled compound in good yield on an industrial scale, by using a β-keto ester and readily available L-valine-tert-butyl ester as asymmetric carbon source and hydrolyzing a specific triester obtained as a starting material.
CONSTITUTION: A β-keto ester expressed by formula I (R1 is lower alkyl) is reacted with an L-valine-tert-butyl ester expressed by formula II to give an enamine expressed by formula III, which is then treated with an alkali metal organic amide. The resultant compound is then reacted with an alkylidenemalonic acid ester expressed by formula IV (R2 is R1, cycloalkyl or aryl; R3 is same as R2), and the resultant product is then hydrolyzed to afford a triester expressed by formula V to afford the aimed compound expressed by formula VI (R4 is H), which is then esterified to give the aimed compound expressed by formula VI (R4 is R1).
USE: A synthetic intermediate for natural physiologically active substances, etc., e.g. agricultural chemicals such as insect pheromones, medicines such as prostaglandins, steroidal compounds, etc.
TOMIOKA KIYOSHI
YASUDA KIMISUKE
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