The present invention concerns a process for preparing each of the 4 individual diastereomers of formula (I) in stereochemically pure form from a single enantiomerically pure precursor. The tetracyclic ringsystem having cis-fused five and seven membered rings is formed in a base-catalysed cyclization reaction. The invention further relates to the thus obtained cis-fused tetracyclic alcohol intermediates and methanamine end-products, and the methanamine end-products for use as a medicine, in particular as CNS active medicines ##STR00001##
The present invention relates to a novel process for the production of [2-(4-fluoro-benzyl)-phenyl]-acetic acid, a compound obtainable from phthalic anhydride. The process comprises the subsequent steps a) through e): a) reacting phthalic anhydride with fluorobenzene or a derivative thereof in appropriate reaction conditions; b) over reducing the product obtained in step a) at the ketone moiety; c) reducing the product obtained in step b) with sodium dihydro-bis(2-methoxyethoxy)aluminate (Red-Al) to the corresponding alcohol; d) chlorinating the alcohol obtained in step c); e) inserting CO into the product obtained in step d) through an appropriate Pd-containing catalytic system.In an alternative embodiment, the step e) is replaced by the steps f1) and f2): f1) reacting the product obtained in step d) with sodium cyanide; f2) hydrolysing the product obtained in step f1).The present invention provides a process for the production of [2-(4-fluoro-benzyl)-phenyl]-acetic acid which is suitable for industrial scale reactors (e.g. which is cleaner and more efficient). Also, [2-(4-fluoro-benzyl)-phenyl]-acetic acid is obtained as a crystalline material with a purity >95%.
