Isatins 3-C annulation vs ring-opening: Two different pathways for synthesis of spiro compounds via multicomponent reactions

•The isatins 3-C annulation to give spiro compounds.•A new pathway for synthesis of spiro compounds via ring-opening of isatins.•The different strategies for construction of spiro compounds.•The catalyst Amberlyst-15 could be easy recycled and reused for many time.