Patent ID: 6864367

Claim:
A process for producing a compound represented by the formula: [wherein, Z is an electron-withdrawing group; W is an optionally substituted ethylene or an optionally substituted vinylene, and when the ethylene or the vinylene has two substituent groups, said substituent groups may be bound to each other to form an optionally substituted ring; R 3 is a hydrogen atom or an optionally substituted hydrocarbon group; and X is a divalent group (however, when W is an optionally substituted vinylene, —X—CH 2 —Z is not —X 1 —X 2 —CH 2 —Z (wherein, X 1 is a sulfur atom or an optionally substituted nitrogen atom; X 2 is an optionally substituted ethylene))] or a salt thereof, which comprises subjecting a compound represented by the formula: [wherein, each symbol has the same meaning described as above] or a salt thereof to a cyclization reaction in a solvent containing a carbonic diester.