| abstract |
A process for preparing compounds of general formula (I> <IMAGE> wherein R<1> represents a hydrogen atom or a lower alkyl group; R<2> represents a hydrogen atom, a lower alkyl group which may be substituted with a halogen atom or a hydroxy group, or a lower alkanoyl group which may be substituted with a halogen atom; X represents a hydrogen atom or a halogen atom; n is an integer of 1 or 2; with the proviso that when n is 1, R<2> should not be a lower alkyl group substituted with a halogen atom, which comprises (a) cyclizing a compound of general formula (II> <IMAGE> wherein R<1>, R<2>, X and n have the same meanings as defined above; and R<3> and R<4>, which may be the same or different, each represents a lower alkyl group; with the proviso that when n is 1, R<2> should not be a lower alkyl group substituted with a halogen atom, or (b) cyclizing a compound of general formula (III> <IMAGE> wherein R<1>, R<2>, X and n have the same meanings as defined above and R<5> represents a lower alkyl group to form a compound of general formula (IV> <IMAGE> wherein R<1>, R<2>, R<5>, X and n have the same meanings as defined above, and then hydrolyzing this compound. |