Benzene → N-(3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-benzopyran-2-yl)-acetylguanidine

Participants

Reaction Steps

To a solution composed of 8.82 g (31.7 mmol) of (3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-benzopyran-2-yl)acetic acid, 5.66 g of thionyl chloride and 20 ml of benzene was added 2 drops of N,N-dimethylformamide, and the mixture was refluxed for 2 hours. Low-boiling substances were distilled off from the reaction mixture under reduced pressure. The residue was dissolved in 20 ml of dioxane and the solution was added dropwise to a solution composed of 65 millimoles of guanidine, 7.5 ml of ethanol and 25 ml of dioxane at room temperature. Thereafter, the resultant mixture was stirred at room temperature for 1 hour and so obtained reaction mixture was poured into water and extracted with diethyl ether. The ether extract was washed with a saturated aqueous solution of sodium chloride and then dried over anhydrous sodium sulfate. Low-boiling substances were distilled off under reduced pressure. The residue was purified by silica gel column chromatography and recrystallized from methylene chloride/diethyl ether/n-hexane to give 5.1 g of N-(3,4-dihydro-6-methoxy-2,5,7,8-tetramethyl-2H-benzopyran-2-yl)-acetylguanidine [Compound (1)], which shows the following physical characteristics.

Provenance & Evidence