反应详情

A three-neck flask fitted with a mechanical stirrer was charged with H2O (1.1 L), CH2Cl2 (1 L) and Na2CO3 (254.4 g, 2.4 mol) and the mixture chilled to ca 5° C. To the chilled mixture was then added the O-methylisourea hydrogen sulfate from above, tetrabutylammonium bromide (0.5 g) and methyl chloroformate (556 mL, 7.2 mol). The mixture was stirred vigorously and 25% NaOH (144 g in ca. 600 mL) was added over 0.5 h. After the last addition, the mixture was stirred for an additional 2 h and then filtered through Celite to remove inorganic salts (Na2SO4). The layers were separated and the organic layer dried (Na2SO4), filtered and concentrated to give the title compound as a thick syrup. The syrup was dried in vacuo overnight during which time it solidified to give 114.7 g (0.6 mol. 53%) of 1,3-dimethoxycarbonyl-O-methylisourea.

1. customA three-neck flask fitted with a mechanical stirrer
2. temperaturethe mixture chilled to ca 5° C
3. additionAfter the last addition
4. stirringthe mixture was stirred for an additional 2 h
5. filtrationfiltered through Celite
6. customto remove inorganic salts (Na2SO4)
7. customThe layers were separated
8. dry with materialthe organic layer dried (Na2SO4)
9. filtrationfiltered
10. concentrationconcentrated