A mixture of potassium carbonate (107 mg, 0.774 mmol), 1-{[isocyano(phenyl)methyl]sulfonyl}-4-methylbenzene (C21, see Organic Syntheses; Wiley & Sons: New York, 2004; Collect. Vol. 10, p. 692) (0.209 g, 0.770 mmol) and tert-butyl 4-{[(1E)-pyrimidin-4-ylmethylene]amino}piperidine-1-carboxylate (C13) (582 mg, 2.00 mmol) in DMF (3 mL) was stirred for 18 hours at room temperature, then diluted with aqueous sodium hydroxide solution (1 N, 50 mL). The mixture was extracted with ethyl acetate, and the combined organic layers were washed with aqueous lithium chloride solution, dried over magnesium sulfate, filtered, and concentrated in vacuo. Purification via silica gel chromatography (Eluants: 50%, then 75% ethyl acetate in heptane) provided the product as a cream-colored solid. Yield: 267 mg, 0.658 mmol, 85%. APCI m/z 406.0 (M+1). 1H NMR (400 MHz, CDCl3) δ 1.49 (s, 9H), 1.82-1.92 (m, 2H), 2.17 (br d, J=12 Hz, 2H), 2.77-2.86 (m, 2H), 4.26-4.34 (m, 2H), 4.93 (tt, J=12, 4 Hz, 1H), 7.20 (dd, J=5.3, 1.5 Hz, 1H), 7.32-7.36 (m, 3H), 7.42-7.45 (m, 2H), 7.80 (s, 1H), 8.54 (d, J=5.3 Hz, 1H), 9.28 (d, J=1.3 Hz, 1H).
