Sodium hydride → HCID 13435061, compound

Participants

Reaction Steps

Trimethyl-sulphoxonium iodide (1 g) was reacted with 50% sodium hydride (0.22 g) in dimethylformamide (30 ml) under stirring at room temperature for 30 minutes, then a solution of 2-trans-[2-(3-methoxy-phenyl)-ethenyl]-3-ethyl-4-oxo-4H-pyrido[1,2-a]pyrimidine-7-carboxylic acid, methyl ester, m.p. 177°-179° C., (1.27 g) in dimethylformamide (20 ml) was added. The mixture was allowed to react under stirring at room temperature for 2 hours, then it was diluted with ice water and the precipitate was filtered, so obtaining 1.19 g of 2-trans-[2-(3-methoxy-phenyl)-ethenyl]-3-ethyl-6,7-methylen-4-oxo-4H-pyrido[1,2-a]pyrimidine-7-carboxylic acid, methyl ester (m.p. 184°-188° C.), which was treated with 0.5% KOH in 95% ethanol solution (40 ml) at reflux temperature for 15 minutes. After cooling the reaction mixture was diluted with water and acidified with acetic acid and the precipitate was filtered: crystallization from CH 2 Cl2 /methanol gave 2-trans-[2-(3-methoxy-phenyl)-ethenyl]-3-ethyl-6,7-methylen-4-oxo-4H-pyrido[1,2-a]pyrimidine-7-carboxylic acid (0.65 g), m.p. 184°-188° C. NMR (CF3COOD) δ: 1.22(d.d) (one of 6,7-methylen protons), 1.36(t) (--CH2 --CH3), 2,96(m)(--CH2CH3 and 6,7-methylen proton), 4.12(s) (OCH3), 5.50(d.d) (c-6 proton), 7.03(d) (c-9 proton), 7.36(d) (Hβ -vinyl proton), 7.68(d) (Hα -vinyl proton), 7.18-7.70(m) (4-phenyl protons), 8.26(d) (c-8 proton), JHαHβ =16 Hz.

Provenance & Evidence