Patent ID: 8252751

Claim:
A substantially pure compound of formulae (I A), (I B), (X A), (X B), (Y A) or (Y B) wherein R′ represents and R″ represents hydrogen, hydroxy, C 1 -C 7 alkoxy, C 1 -C 8 -alkanoyloxy, or R 5 R 4 N—CO—O—, where R 4 and R 5 independently are C 1 -C 7 alkyl or phenyl which is unsubstituted or substituted by a substitutent selected from C 1 -C 7 alkyl, C 1 -C 7 alkoxy, halogen and trifluoromethyl and where R 4 additionally is hydrogen; or R 4 and R 5 to gether represent C 3 -C 6 alkylene; in free form or in form of a pharmaceutically acceptable acid addition salt.