N-Benzyl-4-piperidone (I) was reacted with a Grignard reagent prepared from 4-fluorobromobenzene (II) to give the carbinol (III). The benzyl group was removed by catalytic hydrogenation and the resulting amine (IV) was alkylated with 3-bromopropionaldehyde ethylene acetal (V) to the alcohol (VI). Ring closure in hydrochloric acid gave the bicyclic endo-alcohol [(?-VII] along with some of the exo-isomer removed by crystallization. [(?-VII] was resolved by crystallization with (R,R)-tartaric acid mono-4-chloroanilide (VIII) to give [(+)-VII] of yet unknown absolute configuration. The latter was acylated with propionic anhydride followed by crystallization with hydrogen chloride in ether to furnish the end product.

N-Benzyl-4-piperidone (I) was reacted with a Grignard reagent prepared from 4-fluorobromobenzene (II) to give the carbinol (III). The benzyl group was removed by catalytic hydrogenation and the resulting amine (IV) was alkylated with 3-bromopropionaldehyde ethylene acetal (V) to the alcohol (VI). Ring closure in hydrochloric acid gave the bicyclic endo-alcohol [(?-VII] along with some of the exo-isomer removed by crystallization. [(?-VII] was resolved by crystallization with (R,R)-tartaric acid mono-4-chloroanilide (VIII) to give [(+)-VII] of yet unknown absolute configuration. The latter was acylated with propionic anhydride followed by crystallization with hydrogen chloride in ether to furnish the end product.