Thiophene → (+/-)-1-(3,5-Dimethylbenzoyl)-2-(phenylmethyl)-4-piperidinone

Participants

Reaction Steps

A mixture of intermediate 2 (3.2 g), 1-(diphenylmethyl) piperazine (2.5 g) and aluminum tributoxide (2 g) in toluene (250 ml) was hydrogenated for 48 hours at 50° C., with palladium on activated carbon (10%; 2 g) as a catalyst in the presence of thiophene (4% solution; 1 ml). After uptake of hydrogen (1 equiv), the catalyst was filtered off and the filtrate was evaporated. The residue was purified by high-performance liquid chromatography over silica gel (eluent: CH2Cl2/CH3OH 100/0, upgrading to 90/10). Two pure fractions were collected and their solvent was evaporated, resulting in residue 1 and residue 2. Residue 1 was suspended in DIPE. The precipitate was filtered off and dried, yielding 0.94 g (17%) of (±)-cis-1-(dimethylbenzoyl)-4-[4-(diphenylmethyl)-1-piperazinyl]-2-(phenylmethyl) piperidine (compound 12; mp. 100.8° C.). Residue 2 was dried, yielding 0.2 g (3.6%) of (±)-trans-1-(dimethylbenzoyl)-4-[4-(diphenylmethyl)-1-piperazinyl]-2-(phenylmethyl)piperidine (compound 13).

Provenance & Evidence