Acid Hydrazides, Potent Reagents for Synthesis of Oxygen-, Nitrogen-, and/or Sulfur-Containing Heterocyclic Rings

A study was conducted to provide practical guidance for synthetic chemists on the synthesis of oxygen-, nitrogen-, and sulfur-containing heterocyclic rings. Reaction of benz(g)indole dicarboxylate 5 with hydrazine hydrate in refluxing ethanol and a catalytic amount of pyridine chemoselectively produced only 63% of benz(g)indole monocarbohydrazide 7 instead of the expected dicarbohydrazide 6 wherein the C3carboethoxy group remained unchanged toward nucleophile hydrazine hydrate. The resistance of the heterocycles formed, starting with five- and six-membered rings. These systematic collections in the study expanded the ample possibilities to the synthetic methods accessed by the chemistry for synthesis of heterocyclic compounds and would be useful to pick the route for further research.