| 摘要 |
The present invention relates to a process for preparing a compound of formula (I), wherein R<1> is R<2>O(C=O)- or R<3>(C=O)-, R<2> is (C1-C4)alkyl, and R<3> is (C1-C4)alkyl or phenyl optionally substituted with from one to three substituents independently selected from (C1-C4)alkyl, (C1-C4)alkoxy, halo or trifluoromethyl, comprising: a) reacting a compound of formula (III), wherein R<1> is R<2>O(C=O)- or R<3>(C=O)-, R<2> is (C1-C4)alkyl, and R<3> is (C1-C4)alkyl or phenyl optionally substituted with from one to three substituents independently selected from (C1-C4)alkyl, (C1-C4)alkoxy, halo or trifluoromethyl, with a methenylation agent to form a compound of formula (II), wherein R<1> is R<2>O(C=O)- or R<3>(C=O)-, R<2> is (C1-C4)alkyl, and R<3> is (C1-C4)alkyl or phenyl optionally substituted with from one to three substituents independently selected from (C1-C4)alkyl, (C1-C4)alkoxy, halo or trifluoromethyl and; b) reacting said compound of formula (II), so formed, with a strong acid. The present invention further comprises the additional step of reacting the compound of formula (I) with hydroxide to form a compound of formula (VI), and reacting said compound of formula (VI) so formed with a benzyl halide and a base to form a compound of formula (VII). The present invention relates also to the novel intermediates of formulae (I), (II) and (III). |
