Water → 4-methyl-4H-pyrrolo[2,1-c][1,4]benzoxazine-4-acetic acid ethyl ester

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Reaction Steps

A solution of the compound of formula 2, N-(2-hydroxyphenyl)pyrrole (5 g), described in Example 1, ethyl acetoacetate (4.3 g) and p-toluenesulfonic acid (0.5 g) in benzene (1,500 ml) is stirred and heated at reflux with a Dean-Stark water trap for 3 hr. Ethyl acetoacetate (1.0 g) is added and the reaction mixture kept under the refluxing condition overnight. After being cooled, the mixture is washed with a 5% solution of sodium bicarbonate and then water. The benzene solution is dried (MgSO4), filtered and evaporated. The crude product is purified by chromatography on a column of silica gel. Elution with chloroform gives 4-methyl-4H-pyrrolo[2,1-c][1,4]benzoxazine-4-acetic acid ethyl ester (3; R1 and R2 = H,R3 = CH3, n = 1, X = 0 and A = COOC2H5), νmaxCHCl3 1,725, 1,600, 1,505, 1,345, 1,080, 1,031 cm-1.

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