[H-].[Na+].[CH3:3][O:4][C:5]1[CH:14]=[CH:13][C:8]([CH:9]=[CH:10][CH:11]=O)=[CH:7][CH:6]=1.[CH3:15][O:16]/[C:17](/[CH3:23])=[CH:18]\[C:19]([O:21]C)=[O:20]>O1CCCC1>[CH3:15][O:16][C:17]([CH:23]=[CH:11][CH:10]=[CH:9][C:8]1[CH:13]=[CH:14][C:5]([O:4][CH3:3])=[CH:6][CH:7]=1)=[CH:18][C:19]([OH:21])=[O:20]16.5 g of an 80% by weight suspension of sodium hydride in white oil (corresponding to 0.55 mol of NaH) were mixed with 500 ml of anhydrous tetrahydrofuran and, while stirring efficiently at 50° to 60° C., a mixture of 81 g (corresponding to 0.5 mol) of p-methoxycinnamaldehyde and 65 g (corresponding to 0.5 mol) of methyl β-methoxycrotonate was added dropwise. The rate of this dropwise addition was chosen so that the mixture continued to boil gently. It was then stirred at 65° C. for 3 hours and subsequently at room temperature overnight. To work up the reaction mixture was cooled and mixed with 0.5 l of ice-water and then extracted with methyl tertbutyl ether. The remaining alkaline aqueous phase was acidified with dilute hydrochloric acid while cooling in ice, and the precipitate was filtered off and thoroughly washed with water. Drying resulted in 83 g of the title compound of melting point 187° C. (after recrystallization from ethyl acetate), corresponding to a yield of 64%.
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