反应详情

7-methyl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxylic acid, methyl ester (5.5 g; m.p. 146°-148° C.), prepared according to Example 1, was reacted with sulfuryl chloride (3.6 g) in dichloroethane (150 ml) under stirring at room temperature for 30 minutes. The reaction mixture was poured into ice water containing NaHCO3 : the organic phase was separated and evaporated in vacuo to dryness: crystallization from methanol gave 6-chloro-7-methyl-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxylic acid, methyl ester (4.28 g), m.p. 218°-220° C., which was reacted with benzaldehyde (3.5 g) in methanol (150 ml) in the presence of sodium methoxide (2.68 g) under stirring at reflux temperature for 24 hours. The precipitate was filtered and dissolved in a mixture of dimethylformamide and formic acid; the solution was diluted with ice water and the precipitate was filtered and washed with water until neutral. Crystallization from CH2Cl2 -methanol gave 3.1 g of 6 -chloro-7-trans-(2-phenyl-ethenyl)-5-oxo-5H-thiazolo[3,2-a]pyrimidine-2-carboxylic acid, m.p. 265°-270° C. dec., N.M.R. (CF3COOD-CDCl3) δp.p.m.: 7.59 (d) (1H,β-ethenyl proton), 7.40-7.80 (m) (5H, phenyl protons), 8.01 (d) (1H,α-ethenyl proton), 8.88 (s) (1H, C-3 proton); JHαHβ =16 Hz.

1. customthe organic phase was separated
2. customevaporated in vacuo to dryness
3. customcrystallization from methanol