91% |
With palladium 10% on activated carbon; hydrogen; In ethyl acetate; at 20℃; |
[0510] To a 3 L flask under nitrogen was charged Pd on C,wet, Degussa (10percent Pd, 50percent water) (8.120 g, 76.30 mmol)then EtOAc (1.706 L). The mixture was degassed viaN2/vacuum cycles (3x), then a solution of 1-benzyl-4-tertbutylpiperidine- ,4-dicarboxylate 21 (243 .7 g, 7 63.0 mmol)in EtOAc (243.7 mL) was added. Mixture was stirred under ahydrogen atmosphere overnight. Hydrogen was replenishedand mixture was stirred for a further 3.5 hr. Methanol ( 60 mL)was added to aid dissolution of precipitate then filteredthrough celite, washing through with methanol. Filtrate concentratedin vacuo to leave a brown oil with a slight suspensionofawhite solid, 138.6 g. Solid removed by filtration, andwashed with minimal EtOAc. Filtrate was concentrated invacuo to leave desired product as a light brown oil (129 g,91 percent). 1H NMR (500 MHz, DMSO-d6) o2.88 (dt, 2H), 2.44(td, 2H), 2.23 (tt, lH), 1.69-1.64 (m, 2H) and 1.41-1.33 (m,11H). |
76% |
With hydrogen;5%-palladium/activated carbon; In ethyl acetate; at 20℃; under 760.051 Torr; for 8h; |
To a solution of 1-benzyl 4-fetaut-butyl piperidine-l,4-dicarboxylate in EtOAc (0.1 M), a catalytic amount of Pd/C (5 percent) was added and the atmosphere in the reaction vessel charged with H2 (1 atmosphere). The reaction mixture was stirred vigorously at RT for 8 h. The solution was filtered and the filtrate concentrated in vacuo to afford the title compound (76 percent); MS (ES+) m/z 186(M+H)+ |
|
With palladium on activated charcoal; hydrogen; In ethyl acetate; at 20℃; under 2068.65 Torr; for 18h; |
1 -Benzyl 4-tert-butyl piperidine- 1 ,4-dicarboxylate (11.3 g, 35.4 mmol) was dissolved in ethylacetate (120m1), Pd/C was added (2.0 g, 18.79 mmol), then the mixture was hydrogenated at 20°C, 40 psi for 18 hrs. The reaction mixture was filtered and concentrated to yield tert-butyl piperidine-4-carboxylate. lH-NMR (500 MHz, CDC13) oe ppm 3.0825 (d, J12.5 Hz, 2H), 2.625 (t, J=12 Hz, 2H), 2.281-2.341 (m, 1H), 1.846 (d, J= 13.5Hz, 2H), 1.681(b, 1H), 1.558-1.608(m, 1H,) 1.447 (s, 9H). |