海人草有効成分ならびに関連化合物の研究 第44報

4-Isopropylprolineおよび4-Isopropenylprolineの合成 (ii)

抄録

Ethyl 2-oxo-3-chloro-5-(1-methyl-2-ethoxyethyl)-3-piperidinecarboxylate (VI) was prepared from 2-(1-methyl-2-ethoxyethyl) acrylonitrile (III) by the same method as that described in Part XLIII of this series. Heating of (VI) with hydrochloric acid and subsequent treatments afforded methyl 1-acetyl-4-(1-methyl-2-ethoxyethyl)-2-pyrrolidinecarboxylate (IX) and its 4-(1-methyl-2-hydroxyethyl) compound (X). On heating (IX) with hydrobromic acid, 1-methyl-2-ethoxyethyl group in 4-position was converted to isopropenyl group, while the treatment of (X) with phosphorus tribromide and organic amine was found to convert the 1-methyl-2-hydroxyethyl group to isopropenyl group. A new amino acid, 4-isopropenylproline (XV), was prepared by the foregoing two different methods.