Domino Relay Olefin Metathesis of Triallyl Oxindole and Indole Precursors to Access Cyclic Indoxyls and Carbazoles

Abstract

We herein disclose domino relay metathesis sequences using triallyl 3‐oxindole and indole precursors to access C2‐quaternary cyclic pseudooxindole and carbazole ring systems. Triallyl 3‐oxindoles undergo domino ring closing metathesis (RCM) and cross metathesis (CM) to provide C2‐spirocyclic 3‐oxindoles. Intriguingly, a catalyst specific relay metathesis sequence involving ring closing‐ring opening‐ring closing and cross metathesis (RC‐RO‐RC‐CM) of these trienes is established to provide fused bicyclic indoxyl dimers in high yields. Further, the CM of indoxyl dimer with methyl acrylate affords a new class of fused monomeric 3‐oxindole derivative. Moreover, a domino RCM‐CM process of triallyl indoles is demonstrated, enabling a quick access to dihydro‐carbazoles and carbazoles.