A method for the production of racemic and optically active 11 - bromine - 14 - oxo - 15 - hydroxy imino - e - homoeburnanen

摘要

A process for the preparation of racemic and optically active 11-bromo- E-homoeburnane derivatives of general formula (Ia), IMAGE (wherein R represents a C1-6 alkyl group) and acid addition salts thereof comprises treating a mixture of racemic or optically active brominated 14-oxo-E- homoeburnane derivatives of formulae (IIIa) and (IIIb), IMAGE (wherein R is as defined above) or a mixture of respective acid addition salts thereof with a nitrosating agent and subjecting the resultant mixture of racemic or optically active brominated 14- oxo-15-hydroxyimino-E- homoeburnane derivatives of formulae (Ia) and (Ib). IMAGE (wherein R is as defined above) or respective acid addition salts thereof to selective crystallisation, whereby the desired 11-bromo-E-homoeburnane derivative of formula (Ia) is obtained, which derivative if desired, is converted into an acid addition salt thereof or resolved.