Trifluoroacetic acid → 4-(1,2-Dihydro-5-acenaphthylenyl)piperidine

Participants

Reaction Conditions

Reaction Steps

To a solution of tert-butyl 4-(1,2-dihydro-5-acenaphthylenyl)-4-hydroxy-1-piperidinecarboxylate (0.44 g, 1.24 mmol) in dichloromethane (4 mL) was added triethylsilane (1.10 mL, 6.22 mmol) under nitrogen. The mixture was cooled to −30° C. then trifluoroacetic acid (0.48 mL, 6.22 mmol) added dropwise, maintaining the temperature below −25° C. After 2.5 h, the reaction mixture was allowed to warm to 0° C. and additional trifluoroacetic acid (0.48 mL, 6.22 mmol) added over 5 min. The reaction mixture was allowed to warm to room temperature and left to stir for 3 days. Ice was then added to the reaction mixture, followed by potassium hydroxide to a pH of 14, and the resultant slurry extracted with dichloromethane. The combined organic extracts were dried (Na2SO4) and concentrated in vacuo to yield a yellow oil. The oil was dissolved in methanol and loaded onto an SCX-2 column. The column was washed with methanol, then a 2N solution of ammonia in methanol. Concentration in vacuo of the ammonia solution yielded 4-(1,2-dihydro-5-acenaphthylenyl)piperidine as a pale yellow oil.

Provenance & Evidence