Propargyl bromide → tert-Butyl 4-(prop-2-yn-1-yl)piperazine-1-carboxylate

Participants

Reaction Steps

To a vigorously stirred suspension of piperazine-1-carboxylic acid tert-butyl ester (4.2 g, 22.5 mmol) and K2CO3 (1.2 eq, 27 mmol, 3.7 g) was added propargyl bromide (80 wt % in toluene, 1.2 eq, 27 mmol) dropwise via syringe over 20 minutes. The mixture was stirred at room temperature overnight (about 20 hours), concentrated in vacuo and partitioned between water and EtOAc. The organic-phase was washed twice with water, dried over MgSO4, filtered and evaporated to afford a clear yellow oil that partially solidified upon prolonged standing and was used directly without further purification. 1H NMR (400 MHz, CDCl3) d 1.47 (s, 9H), 2.28 (t, 1H), 2.54 (m, 4H), 3.34 (d, 2H, J=2.4 Hz), 3.49 (m, 4H). MS: m/z 225 (M+1).

Provenance & Evidence