反应详情

Silver cyanate (13.5 g) suspended in anhydrous toluene (90 ml) under nitrogen was treated dropwise with acetyl chloride (5.34 ml) and stirred vigorously for 30 min. The product of step 1) (23 g) dissolved in anhydrous toluene (15 ml) was added and the mixture was stirred for 72 h. Ether (360 ml) was added and the insoluble material was filtered off and washed with a small volume of ether. The combined organic solutions were washed with saturated sodium bicarbonate solution, dried and evaporated. The residue was treated with a solution of sodium methoxide in methanol (25 wt %, 64 ml) at room temperature for 72 h. The reaction was cooled in ice and treated with trimethylsilyl chloride (50.8 ml) and stirred at room temperature overnight. All volatiles were removed in vacuo and the residue partitioned between water and ethyl acetate. Drying and evaporation of the organic solution left a residue, which was chromatographed (SiO2/2:1 isohexane-ethyl acetate then 3:2 isohexane-ethyl acetate) to isolate the major component (12.2 g). This was taken in dry DMF (150 ml) with potassium carbonate (6.95 g) and methyl iodide (7.1 g) for 72 h at room temperature. The mixture was poured into water (2 L), acidified and extracted into ether. Washing with brine, drying and evaporation gave a solid which was boiled in isohexane (200 ml) containing ethyl acetate (3 ml). On cooling the precipitated pale yellow solid was collected and dried, to afford the title compound (10.5 g). δ 1HCDCl3 1.6 (6H, d), 2.44 (3H,s), 3.37 (3H, s), 3.95 (3H, s), 4.66 (1H, br) MS (APCI) (M++H) 297

1. additionwas added
2. stirringthe mixture was stirred for 72 h
3. filtrationthe insoluble material was filtered off
4. washwashed with a small volume of ether
5. washThe combined organic solutions were washed with saturated sodium bicarbonate solution
6. customdried
7. customevaporated
8. additionThe residue was treated with a solution of sodium methoxide in methanol (25 wt %, 64 ml) at room temperature for 72 h
9. temperatureThe reaction was cooled in ice
10. additiontreated with trimethylsilyl chloride (50.8 ml)
11. stirringstirred at room temperature overnight
12. customAll volatiles were removed in vacuo
13. customthe residue partitioned between water and ethyl acetate
14. customDrying
15. customevaporation of the organic solution
16. waitleft a residue, which
17. customwas chromatographed (SiO2/2:1 isohexane-ethyl acetate