Reaktion #50460

Reaktionsgleichung

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

Ethyl chloroformate

→

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

Ausbeute 79.0%

Lösungsmittel

pyridine

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigea solid separated from solution immediately upon addition
2. 2
   SonstigeApproximately half the pyridine was removed in vacuo
3. 3
   workup.ADDITIONthe residual mixture poured over ice
4. 4
   SonstigeThe precipitated solid was collected
5. 5
   Sonstigeair-dried

Vorschrift

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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