Synthesis of 2,3′-spirobi[indolin]-2-ones enabled by a tandem nucleophilic benzylation/C(sp2)–N cross-coupling reaction sequence

Abstract

An efficient complementary strategy for the construction of spiro[pyrrolidin-3,2′-oxindole] derivatives has been described. With the sequential nucleophilic benzylation and copper-catalyzed intramolecular C(sp²)–N cross-coupling reaction of 3-aminooxindoles with 2-bromobenzyl bromides, a wide range of 2,3′-spirobi[indolin]-2-ones were smoothly obtained in moderate to good yields. A plausible catalytic cycle for this tandem reaction process was proposed based on the control experiments. This study represents a new perspective for the synthesis of structurally diverse spirocyclic oxindoles by employing 3-aminooxindole substrates.