Pyridine → cis-2,6-Dimethyl-piperidine-1-carboxylic acid N-(5-fluoro-pyridin-2-yl)-hydrazide

Participants

Reaction Conditions

Reaction Steps

Pyridine (2.40 mL, 29.7 mmol) was added dropwise to an ice cold suspension of triphosgene (4.42 g, 14.9 mmol) in DCM (30.0 mL). cis-2,6-Dimethylpiperidine (2.00 mL, 14.9 mmol) was added and the reaction stirred for 3 hours, then quenched by dropwise addition of HCl (1M aqueous, 30 mL). The mixture was extracted into DCM (3×). The combined organic layers were washed with brine, dried (MgSO4), filtered and evaporated in vacuo. The product was used in the next reaction without purification. cis-2,6-Dimethylpiperidine-carbamoylchloride (1.79 g, 10.2 mmol) was dissolved in DCM (90.0 mL) and DIPEA (2.42 mL, 13.9 mmol) was added followed by (5-fluoro-pyridin-2-yl)-hydrazine (WO 2010 022076, which is incorporated herein by reference in its entirety, 1.18 g, 9.30 mmol) and the reaction heated to 45° C. overnight. The reaction was cooled and quenched into water. The mixture was extracted into DCM (3×). The combined organic layers were washed with brine, dried (MgSO4), filtered and evaporated in vacuo. The residue was purified by FCC using 0-6% [2M NH3 in MeOH] in DCM to give the title compound (1.38 g, 56%). 1H NMR (300 MHz, CDCl3): 1.29 (6H, d, J 7.1 Hz), 1.48-1.90 (6H m), 4.26 (2H, qn, J 6.9 Hz), 6.39 (1H, d, J 2.3 Hz), 6.50 (1H, d, J 2.3 Hz), 6.74 (1H, dd, J 9.0, 3.6 Hz), 7.27 (1H, ddd, J 8.9, 8.0, 2.9 Hz), 8.03 (1H, d, J 2.9 Hz).

Provenance & Evidence