Acetic Acid → 1,1-Dimethylethyl 4-[4-(2-fluoroethyl)-1-piperazinyl]-1-piperidinecarboxylate

Participants

Reaction Steps

1,1-Dimethylethyl 4-oxo-1-piperidinecarboxylate (15.7 g, 78.7 mmol) and 1-(2-fluoroethyl)piperazine (5.2 g, 39 mmol) were dissolved in 150 mL 1,2-DCE. HOAc (3.4 mL, 59 mmol) and TEA (5.5 mL, 39 mmol) were added followed by sodium triacetoxyborohydride (12.5 g, 59.0 mmol). The reaction was stirred for 3 h. TLC revealed the presence of starting material and so an additional 1.5 eq (12.5 g, 59.0 mmol) of sodium triacetoxyborohydride were added. Reaction was allowed to stir overnight. Saturated aqueous NaHCO3 solution was added carefully until the reaction stopped bubbling. Aqueous layer was then extracted with EtOAc (3×). Combined organic layers were dried over MgSO4, filtered and concentrated in vacuo. The resulting crude product was adsorbed onto silica gel and purified by flash chromatography to give title compound of step C (10.2 g, 82%). 1H NMR (400 MHz, DMSO-d6) δ ppm 4.39-4.57 (m, 2H), 3.90 (d, J=12.46 Hz, 2H), 2.61-2.73 (m, 2H), 2.47-2.61 (m, 2H), 2.36-2.47 (m, 8H), 2.24-2.35 (m, 1H), 1.69 (d, J=12.46 Hz, 2H), 1.37 (s, 9H), 1.14-1.26 (m, 2H).

Provenance & Evidence