1-Substituted 3-alkyl/aryl-3-amino-1H, 3H-quinoline-2, 4-diones react with urea in boiling acetic acid to give products depending on the type of substitution in position 3 and at the nitrogen atom of the 3-amino group. Starting compounds bearing a primary amino group in position 3 give 3-(3-acylureido)-2, 3-dihydro-1H-indol-2-ones. Starting compounds bearing a secondary amino group in position 3 react according to the character of the other ...