Diisopropylethylamine → (2-{1-[2,6-Bis-(4-cyano-phenoxy)-pyridine-3-carbonyl]-piperidin-4-yl}-ethyl)-carbamic Acid Tert-butyl Ester

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Reaction Steps

A solution of 2,6-Bis-(4-cyano phenoxy)-nicotinic acid, 0.335 g (0.94 mmol), in 5 ml of DMF was added dropwise to the stirred suspension of 0.489 g (0.94 mmol) of benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate (PyBop) in 5 ml of DMF and followed by N,N-diisopropylethylamine 0.242 g (1.88 mmol) while the temperature was maintained below 5° C. during the addition. The mixture was stirred for 10 min and a solution of (2-piperidin-4-yl-ethyl)-carbamic acid tert-butyl ester (0.214 g, 0.94 mmol) in 2 ml of DMF was added. The mixture was stirred overnight at RT. The solvent was concentrated under reduced pressure and the residue was dissolved in a mixture of water (150 ml) and ethyl acetate (150 ml). The pH was adjusted to 2-3 with 6 N HCl and the phases were separated. The aqueous phase was extracted with ethyl acetate. The combined organic phase was washed with 10% solution of potassium hydrogen sulphate followed by saturated sodium bicarbonate solutiona and saturated brine solution, and dried over sodium sulphate and concentrated. The crude oily residue was purified by column chromatography using hexane-ethyl acetate (10:2) to afford 0.4 g of the required product. Percentage purity: 36.3%, (M+1)=567.2. 1H NMR (DMSO-d6): δ 1.35 (3H, m), 1.38 (9H, s), 1.65 (2H, m), 2.71 (2H, m), 2.95 (4H, m), 3.75 (2H, m), 6.80 (1H, t), 6.95 (1H, d), 7.32 (4H, d), 7.68 (1H, m), 7.85 (4H, d).

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