Reaction Steps
4-(Dimethylamino)pyridine (3.3 mg, 0.0274 mmol) was added to a stirred solution of 3-(benzyloxy)-2-ethyl-1-(2-hydroxyethyl)pyridin-4(1H)-one (6) (149 mg, 0.547 mmol), 5-(benzyloxycarbonylamino)-4-oxopentanoic acid (5) (145 mg, 0.547 mmol) and N,N′-dicyclohexylcarbodiimide (118 mg, 0.574 mmol) in dichloromethane (8 mL). After 24 h, the resulting suspension was filtered through cotton wool, eluting with dichloromethane. The filtrate was concentrated in vacuo and the residue was purified by flash chromatography on silica gel, eluting with ethyl acetate then methanol, to give the title compound 7 (247 mg, 87%) as a colourless oil, RF 0.7 (MeOH); δH (300 MHz; CDCl3) 7.46-7.20 (11H, m, Ar and Pyr 6-H), 6.40 (1H, d, J 9.0 Hz, Pyr 5-H), 5.97 (1H, br s, NH), 5.22 (2H, s, PhCH2), 5.09 (2H, s, PhCH2), 4.22 (2H, t, J 6.0 Hz, OCH2CH2), 4.10-3.95 (4H, m, HNCH2 and OCH2CH2), 2.71-2.50 (6H, m, CH3CH2 and C(O)CH2CH2) and 0.99 (3H, t, J 7.0 Hz, CH3) δC (75 MHz; CDCl3) 204.7, 174.3, 172.3, 156.9, 146.2, 139.4, 138.0, 136.8, 129.1, 128.9, 128.8, 128.7, 128.5, 128.4, 128.3, 117.8, 73.3, 67.3, 63.3, 51.5, 50.9, 34.4, 27.9, 19.8 and 13.5.
