Triphenylphosphine → Ammonium Hydroxide

Participants

Reaction Steps

To the solution of 3.4 g (11.6 mmoles, 1 eq) of 2-{[6-(3,4-dimethoxy-phenyl)-piperidin-2-ylmethyl]-amino}-ethanol and 0.20 g (17.5 mmoles, 1.5 eq) of triphenyl phosphine in 120 mL of THF, is added 1.9 mL (12.7 mmoles, 1.1 eq) of diethyl azodicarboxylate, and the reaction is stirred at room temperature overnight. At that time there is no starting material shown on TLC. After removal of the solvent, the residue is taken in ethyl acetate and extracted with 1 N HCl solution. The acidic aqueous is basified with 1N NaOH to pH 10, and extracted with dichloromethane 3 times. The organic extracts are washed with brine, dried over Na2SO4 and concentrated to give oil product, which is purified by flash chromatography on silica gel eluted with 50:10:1 DCM:MeOH:NH4OH, to afford 6-(3,4-dimethoxy-phenyl)-octahydropyrido[1,2-a]pyrazine as a brownish stick solid (0.85 g, 27%). Analysis: 1H NMR (300 MHz, CDCl3): 6.80 (3H, m), 3.87 (3H, s), 3.84 (3H, s), 3.29 (1H, s), 2.92-2.68 (4H, m), 2.60 (2H, m), 2.13 (1H, m), 1.82-1.05 (8H, m). MS (LC-MS): Calculated for C16H18N2O4 302.33, found 303.39 (M+1).

Provenance & Evidence