To a solution of potassium tert-butoxide (468 mg, 4.17 mmol) in dry DMSO (20 ml) was slowly added nitromethane (225 ul, 4.17 mmol) under nitrogen. The resulting mixture was stirred for 15 min at room temperature before tert-butyl(1-(4-(6-chloro-5-nitro-3-phenylpyridin-2-yl)phenyl)cyclobutyl)carbamate (1 g, 2.08 mmol) was added. The resulting mixture was stirred for 1 hour at room temperature. A saturated solution of NH4Cl was added and the mixture was extracted with AcOEt (3×50 ml). The combined organic phases were washed with water (3×20 ml), dried over Na2SO4 and concentrated to dryness under reduced pressure. The resulting residue was used directly without purification. 1H NMR (500 MHz, CDCl3): 8.60 (1H, s), 7.44-7.35 (7H, m), 7.30-7.28 (2H, m), 6.21 (2H, s), 5.09 (1H, s), 2.52-2.20 (4H, m), 2.00-1.95 (1H, m), 1.79-1.65 (1H, m), 1.40-1.10 (9H, br).
