3-substituted acylindole 8a is readily converted into 4-aminopyrazol-3-ylindoles 20, and into 22. Indole reacts with chloroacetyl chloride to yield: 3-chloroacetylindole 9 which could also be utilized for synthesis of a number of 3-substituted indoles.
A study probing the scope of acylation of indoles with dicarboxylic acids in acetic anhydride has been performed, resulting in products incorporating 3-acylindole- or 1-acylindole motifs depending on the choice of the acid reactant. Synthetically useful results were only obtained from reactions involving malonic acid or Meldrum's acid. Correlations to previous studies have also been made and discussed