Реакция #50460

Уравнение реакции

5-nitro-6-methyl-2-aminobenzoic acid

Ethyl chloroformate

→

6-nitro-5-methyl-2-ethoxy-3,1-benzoxazin-4-one

Выход 79.0%

Растворители

pyridine

Условия реакции

Обработка

1. 1
   Другоеa solid separated from solution immediately upon addition
2. 2
   ДругоеApproximately half the pyridine was removed in vacuo
3. 3
   workup.ADDITIONthe residual mixture poured over ice
4. 4
   ДругоеThe precipitated solid was collected
5. 5
   Другоеair-dried

Методика

A solution of 4.0 g (20.4 mmoles) of 5-nitro-6-methyl-2-aminobenzoic acid in 50 mL of dry pyridine was cooled in an ice-water bath under inert atmosphere. Ethyl chloroformate (Aldrich), 10 mL (105 mmoles), was added dropwise over a 15 minute period. A mild exotherm was observed and a solid separated from solution immediately upon addition. The suspension was stirred at room temperature under inert atmosphere overnight. Approximately half the pyridine was removed in vacuo, and the residual mixture poured over ice. The precipitated solid was collected and air-dried. 4.0 g (79% yield) 6-nitro-5-methyl-2-ethoxy-3,1-benzoxazin-4-one was obtained. NMR (DMSO-d6): 1.37(t,3H,J=7.2 Hz), 2.71(s,3H), 4.50(q,2H,J=7.2 Hz), 7.40(d,1H, J=9.0 Hz), 8.19(d,1H,J=9.0 Hz). IR(nujol): 1765 cm-1 (lactone carbonyl). MS(m/z): 250(M+).

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