- Syntheses of 3-Methylpyrrole via Methyl 4-Methylpyrrole-2-carboxylate: A Thermal Oxazolone-Pyrone Rearrangement
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3-Ethoxy-2-methylpropenal with hippuric acid and acetic anhydride gave 4-(3-ethoxy-2-methylallylidene)-2-phenyloxazol-5(4H)-one.By successive treatment with methanolic potassium hydroxide, acetic-hydrochloric acid, and methanolic sodium methoxide, methyl 4-methylpyrrole-2-carboxylate was formed in high overall yield, and was converted into 3-methylpyrrole by hydrolysis and decarboxylation.The oxazolone with sodium hydroxide in acetone or dioxane gave 4-(3-hydroxy-2-methylallyilidene)-2-phenyloxazol-5(4H)-one, isomerized in boiling acetone, or on melting, to 3-benzoylamino-5-methylpyran-2-one. 3-Ethoxy-2-methylpropenal condensed with glycine methyl ester to give an enaminal, cyclized in moderate yield to methyl 4-methylpyrrole-2-carboxylate.
- Cornforth, John,Ming-hui, Du
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p. 1459 - 1462
(2007/10/02)
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