Potassium Carbonate → 4-[4-(3,4-Dihydro-1-methylpyrrolo[1,2-a]pyrazin-6-yl)phenoxy]butan-2-ol fumarate

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Reaction Steps

Toluenesulphonic acid 3-hydroxybutan-1-yl ester (1.8 g) and 1.8 g of potassium carbonate was added at room temperature while stirring and under argon to a solution of 1.5 g of 3,4-dihydro-6-(4-hydroxyphenyl)-1-methylpyrrolo[1,2-a]pyrazine in 20 ml of 2-butanone and the mixture was boiled for 20 hours. The cooled reaction mixture was treated with 100 ml of 2N sodium hydroxide solution and extracted three times with 200 ml of methylene chloride each time. The organic phases were washed twice with 100 ml of water each time, combined, dried with MgSO4 and freed from solvent. The residue, 2.4 g of brown oil, was chromatographed on 50 g of silica gel with methylene chloride/methanol mixtures (50:1 to 20:1) as the eluent. There were obtained 1.2 g of an orange coloured, amorphous solid which was dissolved in a 25-fold amount of ethanol and treated while hot with 1.1 equivalents of a saturated solution of fumaric acid in ethanol. There were obtained 1.5 g (90%) of 4-[4-(3,4-dihydro-1-methylpyrrolo[1,2-a]pyrazin-6-yl)phenoxy]butan-2-ol fumarate (1:1); m.pt.: 156°-157° C. (dec.).

Provenance & Evidence