Regioselective Synthesis of Spiro-Oxindoles via a Ruthenium-Catalyzed Metathesis Reaction

Abstract

Spiro-oxindoles are important heterocyclic motifs found in various alkaloids, many of which exhibit pharmacological properties. Due to the remarkable biological activity of spiro-oxindoles, significant effort has been made towards the synthesis of substituted spiro-oxindoles. In this paper, preliminary results regarding the synthesis of 3,3′-spiro pentacyclo-oxindole derivatives via the ring-closing metathesis of 3,3-diallyl oxindoles are reported. The ring-closing metathesis reaction proceeded smoothly with Grubb’s catalyst-I (2 mol%) in toluene at room temperature. The desired products, 3,3′-spiro pentacyclo-oxindoles, were obtained in good to excellent yields under standard reaction conditions.

Keywords

• oxindole
• 3,3′-diallyl indoles
• spirocyclo-oxindoles
• ring-closing metathesis
• grubb’s catalyst