tert-Butyl isocyanate → 3-tert-Butyl-6-chloro-1H-quinazoline-2,4-dione

Temperatur

-20 °C

To a room temperature solution of 4-chloro-phenylamine (5.0 g, 39.19 mmol) was added di-tert-butyl dicarbonate (9.41 g, 43.11 mmol) portion-wise. The solution was heated to reflux, stirred for 2 hrs, cooled, concentrated, and dissolved in diethylether. The solution was washed with water, sodium bicarbonate and brine, dried over MgSO4, filtered, and concentrated to provide (4-chloro-phenyl)-carbamic acid tert-butyl ester (8.5 g) as a white solid, which was used with no further purification. To a −78° C. solution of (4-chloro-phenyl)-carbamic acid t-butyl ester (5.046, 23.30 mmol) in THF (232 mL) was added 32.9 mL of t-BuLi (1.7 M in pentane, 55.92 mmol) via cannula. The solution was stirred 10 min, warmed to −20° C. and stirred 2 hours further. To the −20° C. red solution was added t-butyl isocyanate (3.33 mL, 29.13 mmol). The solution was stirred at −20° C. for 1 hr, warmed to room temperature, stirred 2 hrs, then heated to reflux and stirred for 12 hrs. The reaction was cooled to room temperature, concentrated and dissolved in diethylether. The solution was washed with water, sodium bicarbonate and brine, dried over MgSO4, filtered, and concentrated to provide 5.87 g of white solid (100%). 1H NMR (300 MHz, CDCl3) δ ppm 1.76 (s, 9H), 6.91 (d, J=8.6 Hz, 1H), 7.48 (dd, J=2.2, 8.5 Hz, 1H), 7.97 (d, J=2.3 Hz, 1H), 9.22 (br s, 1H).

1. customwas used with no further purification
2. stirringstirred 2 hours further
3. stirringThe solution was stirred at −20° C. for 1 hr
4. temperaturewarmed to room temperature
5. stirringstirred 2 hrs
6. temperatureheated
7. temperatureto reflux
8. stirringstirred for 12 hrs
9. temperatureThe reaction was cooled to room temperature
10. concentrationconcentrated
11. dissolutiondissolved in diethylether
12. washThe solution was washed with water, sodium bicarbonate and brine
13. dry with materialdried over MgSO4
14. filtrationfiltered
15. concentrationconcentrated

ORD-Eintrag

ord-84fd0b46efc54a8f968e9ae18bd3bc95

Quelldatensatz

uspto-grants-2005_07

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US06921821B2