1971 Volume 44 Issue 3 Pages 749-753
Another route to the synthesis of nitro, amino, and acetamino derivatives of 2,3-dimethylbenzofuran was explored. The cyclo-dehydration of 3-(m- and p-nitrophenoxy)butanones by means of polyphosphoric acid or sulfuric acid afforded 2,3-dimethyl-4- and -5-nitrobenzofurans, which were then converted by reduction to the corresponding 4- and 5-aminobenzofurans. The 4-, 5-, 6-, and 7-aminobenzofurans were prepared by the Hofmann reaction of the corresponding carboxylic amides. The amines thus obtained were converted to 4-, 5-, and 6-acetaminobenzofurans by acetylation. The 5-, 6-,-and 7-acetaminobenzofurans were also prepared by the cycliza-tion of 3-(p-, m-, and o-acetaminophenoxy)butanones. The 7-nitrobenzofuran was prepared by the Sandmeyer reaction of 7-aminobenzofuran. The four aryloxybutanones, 2,3-dimethyl-4- and -7-nitrobenzofurans, 4-amino-2,3-dimethylbenzofuran, and 2,3-dimethyl-4-, -5-, -6-, and -7-benzofurancarboxylic amides are new compounds.
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