[C:1]([O:9][CH2:10][CH3:11])(=[O:8])[CH2:2][C:3]([O:5]CC)=O.[NH2:12][C:13]1[CH:18]=[C:17]([CH2:19][CH3:20])[N:16]=[C:15]([CH2:21][CH3:22])[C:14]=1[C:23](OC)=[O:24].[Na]>C(O)C>[CH2:21]([C:15]1[N:16]=[C:17]([CH2:19][CH3:20])[CH:18]=[C:13]2[C:14]=1[C:23]([OH:24])=[C:2]([C:1]([O:9][CH2:10][CH3:11])=[O:8])[C:3](=[O:5])[NH:12]2)[CH3:22]Diethyl malonate (14.5 ml) and methyl 4-amino-2,6-diethylpyridine-3-carboxylate (21.3 g) was added to a solution of sodium (2.33 g) in ethanol (60 ml) and the resulting mixture was heated at 150° C. for 20 hours in an autoclave. The mixture was allowed to cool and then volatile material was removed by evaporation and the resultant semi-crystalline solid was triturated with ether. The solid was collected by filtration and dissolved in a minimum of water. The solution as acidified with 2M hydrochloric acid and the resulting precipitate was collected by filtration and washed with water. The solid was dried under vacuum to give ethyl 5,7-diethyl-4-hydroxy-2-oxo-1,2-dihydro-1,6-naphthyridine-3-carboxylate (B) (12.72 g); m.p. 240-242° C.; NMR (CDCl3): 1.34(dt, 6H), 1.52(t, 3H), 2.84(q, 2H), 3.36(q, 2H), 4.52(q, 2H), 6.87(s, 1H), 7.26(s, 1H), 11.41(broad, 1H); mass spectrum (CI, ammonia): 291 (M+H)+ ; microanalysis, found: C, 62.1; H, 6.2; N, 9.7%; C15H18N2O4 requires: C, 62.1; H, 6.3; N, 9.7%.
Loading…
