反应详情

A solution of guanidine hydrochloride (2.3 g., 0.024 mol) and sodium ethoxide (from 0.55 g, 0.024 mol of sodium) in absolute ethanol (24 cm3) was stirred at room temperature for 1 h. The precipitated sodium chloride was removed by filtration and washed with ethanol (4 cm3). Methyl (trans-2,5-dihydro-2,5-dimethyl-1H-pyrrol-1-yl)acetate (3.4 g., 0.02 mol) was added to the combined filtrate and washings obtained above and the solution stoppered and stirred for 18 h. The reaction mixture was then evaporated and the residue crystallised from ethanol to give the product (1.25 g.). The base was suspended in ethanol and acidified with ethanolic hydrogen chloride, the clear solution thus obtained was diluted with ethyl acetate and concentrated by evaporation to precipitate the title compound as the dihydrochloride (1.6 g.) m.p. 210°-11° C.(d).

1. customThe precipitated sodium chloride was removed by filtration
2. washwashed with ethanol (4 cm3)
3. customobtained above and the solution
4. customThe reaction mixture was then evaporated
5. customthe residue crystallised from ethanol
6. customto give the product (1.25 g.)
7. customthe clear solution thus obtained
8. concentrationconcentrated by evaporation
9. customto precipitate the title compound as the dihydrochloride (1.6 g.) m.p. 210°-11° C.(d)