C([C:3](CC)(C([O-])=O)[C:4]([O-])=[O:5])C.[Na].[CH3:13][O:14][C:15]1[N:20]=[C:19]([O:21][CH3:22])[C:18]([CH:23]=[CH:24][C:25](=[O:27])[CH3:26])=[C:17]([O:28][CH3:29])[N:16]=1.[OH-].[K+]>C(O)C>[OH:5][C:4]1[CH2:3][CH:23]([C:18]2[C:19]([O:21][CH3:22])=[N:20][C:15]([O:14][CH3:13])=[N:16][C:17]=2[O:28][CH3:29])[CH2:24][C:25](=[O:27])[CH:26]=1
Diethylmalonate (4.5 g) was added to a solution of sodium metal (0.65 g) in absolute ethanol (30 ml) and the mixture was heated under reflux with stirring. 1-(2,4,6-Trimethoxy-5-pyrimidylbut-1-en-3-one (6.4 g) was added and the mixture was then boiled under reflux for 2 hours. An aqueous solution of potassium hydroxide (3.5 g in 80 ml of water) was added and the mixture was heated under reflux for a further 5 hours. The solution was cooled and extracted with chloroform (50 ml) and then the aqueous layer was heated to 90° C. and carefully acidified (pH 4.5) with dilute aqueous hydrochloric acid. The resultant precipitate was removed by filtration to give 3-hydroxy-5-(2,4,6-trimethoxy-5-pyrimidyl)cyclohex-2-en-1-one (5.2 g) as a pale yellow crystalline solid, mp 215° C. (dec). Extraction of the filtrate with ethylacetate gave a further 0.7 g of product.
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