4-Hydroxypropiophenone (I) was protected as the triisopropylsilyl ether (II) and subsequently brominated with elemental bromine in CCl4 . The resultant bromo ketone (III) was subsequently coupled with 4-hydroxy-4-phenylpiperidine (IV) to afford the racemic amino ketone (V). This was stereoselectively reduced with NaBH4 in EtOH yielding the threo-amino alcohol (VI). Then, desilylation of (VI) with tetrabutylammonium fluoride furnished the racemic phenol compound. Resolution into the enantiomers has been reported by formation of the corresponding D-tartaric acid salts
4-Hydroxypropiophenone (I) was protected as the triisopropylsilyl ether (II) and subsequently brominated with elemental bromine in CCl4. The resultant bromo ketone (III) was subsequently coupled with 4-hydroxy-4-phenylpiperidine (IV) to afford the racemic amino ketone (V). This was stereoselectively reduced with NaBH4 in EtOH yielding the threo-amino alcohol (VI). Then, desilylation of (VI) with tetrabutylammonium fluoride furnished the racemic phenol compound. Resolution into the enantiomers has been reported by formation of the corresponding D-tartaric acid salts. Finally, the title product was obtained by dissolving D-(-)-tartaric salt (VII) in water in the presence of methanesulfonic acid
In a related process, the racemic piperidinyl ketone (VII) was initially resolved employing D-tartaric acid. The target (2S)-piperidinyl propanone (VIII) was then diastereoselectively reduced to the (1S,2S)-alcohol (IX) employing LiBH4 in EtOH. Finally, debenzylation of (IX) by catalytic hydrogenolysis yielded the title compound
In a related process, the racemic piperidinyl ketone (VIII) was initially resolved employing D-tartaric acid and then subjected to a diastereoselective reduction to the (1S,2S)-alcohol (IX) employing LiBH4 in EtOH. Finally, debenzylation of (IX) by catalytic hydrogenolysis with Pd/C in EtOH and methanesulfonic acid, followed by addition of water, yielded the title compound