| abstract |
A process for preparing a compound represented by the formula <CHEM> wherein R<1> is a lower alkyl, cycloalkyl, cycloalkyl-lower alkyl, aryl or aralkyl group which is optionally substituted; R<2> is a group represented by the formula: -COOR': (wherein R' is a lower alkyl or aralkyl which is optionally substituted), lower alkyl, or halogenated lower alkyl, or, R<1> and R<2>, together with adjacent carbonyl group, form a cyclohexanone ring: <CHEM> R<3> is a phenyl group optionally being substituted; and, ring A is a benzene nucleus which is optionally substituted, or a heterocyclic ring containing S or O optionally being substituted; which process is characterized by that a lactone compound represented by the formula: <CHEM> in which R<3> and ring A are as defined above, is allowed to react with a compound of a formula: <CHEM> in which R<1> and R<2> are as defined above in the presence of a base, and then the resulting compound is subject to dehydration and compounds used in the process. |