Syntheses of indolyl-4(3H)-quinazolinones

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2-(1H-Indol-2-yl)-4(3H)-quinazolinones (10, 11) and 2-(2-ethoxy-carbonyl-1H-indol-3-yl)-4(3H)-quinazolin-4-one (15) are prepared by the Fischer indolization of 2-(1-phenylhydrazonoalkyl)- (8, 9) and 2-(2-phenylhydrazono-2-ethoxycarbonylethyl)-4(3H)-quinazolinones (14), respectively, by heating in PPA. When 2-phenylhydrazone derivative (14) is heated in 85% phosphoric acid at 180 °C, besides indolization ester hydrolysis and decarboxylation also occurred to yield 2-(1H-indol-3-yl)-4(3H)-quinazolinone (16). The 3-(1H-indol-3-yl)-4(3H)-quinazolinone (24) is prepared either from the isomeric 3-indolyl derivatives of anthranilamide (21, 23) by heating in 98% formic acid, or in "one pot" procedure from 2-[1-(N-methyl-N-phenylamino)ethyl]-4(3H)-quinazolinone (17) by heating in 98% formic acid in the presence of a few drops of conc. hydrochloric acid. The reaction mechanism is discussed.

Original languageEnglish
Pages (from-to)903-914
Number of pages12
Issue number2
Publication statusPublished - Mar 3 1994


ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmacology
  • Organic Chemistry

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