Triethylamine → tert-Butyl 4-(1-(pyridin-3-yl)ethyl)piperazine-1-carboxylate

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This was prepared using the same procedure as for tert-butyl 4-(1-(pyridin-2-yl)ethyl)piperazine-1-carboxylate, but here using 1-(pyridin-3-yl)ethanol (J. Chem. Soc., Perkin Trans. 1, 2000, 4439-4444) (200 mg, 1.62 mmol), triethylamine (5.0 eq, 8.12 mmol, 1.13 mL), MsCl (2.0 eq, 3.25 mmol, 0.26 mL), CH2Cl2 (8 mL) at 0° C. for 30 minutes. A solution of ether-pentane (1:1, 20 mL) was added, the solid removed by filtration and the solvents removed in vacuo. The residue was then treated with N—BOC piperazine (4.0 eq, 6.50 mmol, 1.21 g) in DMSO (6 mL) at 60° C. for 18 h. Work up as described for tert-butyl 4-(1-(pyridin-2-yl)ethyl)piperazine-1-carboxylate, followed by column chromatography (EtOAc-MeOH, 95:5) gave the product (186 mg, 39% for two steps) as a colourless oil; 1H-NMR (500 MHz, CDCl3) 1.36 (d, J=6.8 Hz, 3H, CH3), 1.42 (s, 9H, C(CH3)3), 2.29-2.45 (m, 4H, piperazine N(CH2)2), 3.38 (t, J=5.0 Hz, 4H, piperazine N(CH2)2), 3.45 (q, J=6.8 Hz, 1H, CH), 7.23 (dd, br, J=7.9, 4.7 Hz, 1H, pyridine H-5), 7.64 (dt, J=7.8, 1.9 Hz, 1H, pyridine H-4), 8.47 (dd, J=4.8, 1.8 Hz, 1H, pyridine H-6), 8.52 (d, br, J=1.9 Hz, 1H, pyridine H-2);

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