| 主权项 |
1. Process for preparing the compounds of general formula I, wherein R1 denotes cyclobutyl, cyclopentyl, cyclohexyl, R-tetrahydrofuran-3-yl, S-tetrahydrofuran-3-yl or tetrahydropyran-4-yl; and R3 denotes hydrogen; said method comprised of the steps of cleaving a compound of general formula II wherein R1 is defined as hereinbefore and R2 independently of one another denote hydrogen, (C1-18-alkyl)carbonyl, (C1-18-alkyl)oxycarbonyl, arylcarbonyl, aryl-(C1-3-alkyl)-carbonyl, aryl-C1-3-alkyl, allyl, RaRbRcSi, CRaRbORc, wherein two adjacent groups R2 may be linked with each other to form a bridging group SiRaRb, CRaRb or CRaORb—CRaORb; with the proviso that at least one substituent R2 is not hydrogen; Ra, Rb, Rc independently of one another denote C1-4-alkyl, aryl or aryl-C1-3-alkyl, while the alkyl groups may be mono- or polysubstituted by halogen; L1 independently of one another are selected from among fluorine, chlorine, bromine, C1-3-alkyl, C1-4-alkoxy and nitro; while by the aryl groups mentioned in the definition of the above groups are meant phenyl or naphthyl groups, which may be mono- or polysubstituted with L1; the protective groups R2 not being hydrogen are cleaved. |
