| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of producing a cyclic compound that is useful in medicines, foods, cosmetics, chemicals and as an intermediate thereof through a shortened process that is safe and suitable for bulk production. SOLUTION: A compound of formula (1) wherein Z means an electron attractive group, W is ethylene which may be substituted or vinylene which may be substituted; R3 is H, a hydrocarbon group which may be substituted, X is a divalent group [when W represents vinylene which may be substituted, -X-CH2-Z is not -X1-X2-CH2-Z (wherein X1 is an S atom or an N atom which may e substituted; X2 is ethylene which may be substituted)]} or its salt is characteristically subjected to the ring closure reaction in a solvent including carbonic diester whereby the objective compound represented by formula (2) [wherein individual symbols are the same as those in formula (1)] or a salt thereof is obtained.
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