反应详情

2-Bromo-2-methylpropionyl bromide (8.9 g) in dichloromethane (20 ml) was added dropwise at 0° to a stirred suspension of 1,1-dimethylurea (3.4 g) in dichloromethane (25 ml) and triethylamine (16 ml). The mixture was stirred for 4 hr. at 22° and the solvent was evaporated. The residue was stirred with saturated sodium hydrogen carbonate solution (40 ml) and extracted with ethyl acetate (3×20 ml). The ethyl acetate solution was dried and evaporated. The residue was stirred with light petroleum (b.p. 40°-60°, 50 ml) and the remaining solid was filtered off and suspended in sodium hydrogen carbonate solution and extracted into ethyl acetate (2×20 ml). The ethyl acetate solution was dried and evaporated, leaving the urea as a pale brown solid, 1.4 g, m.p. 98°-100°, max (Nujol) 3400, 3370 (NH), 1742, 1685 cm-1 (--CONH.CON--), τ (DMSO d6) 8.06 (--C(Me)2), 7.01 (-N(Me)2), 1.6 (--CONHCO--).

1. customat 22° and the solvent was evaporated
2. stirringThe residue was stirred with saturated sodium hydrogen carbonate solution (40 ml)
3. extractionextracted with ethyl acetate (3×20 ml)
4. dry with materialThe ethyl acetate solution was dried
5. customevaporated
6. stirringThe residue was stirred with light petroleum (b.p. 40°-60°, 50 ml)
7. filtrationthe remaining solid was filtered off
8. extractionextracted into ethyl acetate (2×20 ml)
9. dry with materialThe ethyl acetate solution was dried
10. customevaporated