Patent ID: 8907099

Claim:
A compound according to formula IVA, IVB or IVC wherein R 4 , R 5 , R 6 and R 7 independently from each other represent hydrogen, C 1 -C 6 -alkyl, C 1 -C 6 -thioalkyl, C 1 -C 6 -alkoxy, C 6 -C 12 -aryloxy or a C 6 -C 12 -thioaryl group, C 1 -C 6 -alkanoyl or C 7 -C 13 -aroyl group, amino, C 1 -C 6 -alkylamino, C 1 -C 6 -dialkylamino, C 3 -C 12 -cycloalkylamino or C 3 -C 12 -heterocycloalkylamino, C 1 -C 6 -alkylsulphonyl or C 6 -C 12 -arylsulphonyl, halogen, C 1 -C 6 -haloalkyl, trifluoromethyl, cyano, nitro or a heteroaryl group; and R 8 and R 9 independently from each other represent hydrogen or suitable protective groups for aromatic hydroxyl groups.