Lewis-acid catalyzed dehydrative [3+2] cycloaddition reaction: A facile synthetic approach to spiro-benzoindoline oxindoles

• Published in: Tetrahedron letters Vol. 61; no. 25; pp. 152007 - 152011
• Main Authors: Bhandari, Sonal, Kulkarni, Neeraj, Sakla, Akash P., Shankaraiah, Nagula
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier Ltd 18.06.2020; Elsevier
• Subjects: Chemistry; Chemistry, Organic; Formal [3+2] cycloaddition; Friedel–Crafts arylation; Physical Sciences; Science & Technology; Spiro-aziridine oxindole; Spiroannulation; Friedel–Crafts arylation; Formal [3+2] cycloaddition; Spiroannulation; Spiro-aziridine oxindole; DESIGN; ASYMMETRIC-SYNTHESIS; INDOLINE; PERFORMANCE; AZIRIDINES; CONSTRUCTION; Friedel-Crafts arylation; SCAFFOLDS; DERIVATIVES; ONE-POT ACCESS; HYBRIDS
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2020.152007

[Display omitted] •Lewis acid-catalyzed synthesis of new spiro-benzoindoline oxindole scaffold from spiro-aziridine oxindole.•Strategy involves regioselective spiro-aziridine ring opening followed by dehydrative formal [3+2] cycloaddition.•The regioselectivity was confirmed unambiguously by X-ray analysis. An efficient one-pot method for the construction of C–C and C–N bond has been established from activated spiro-aziridine oxindoles using different substituted 2-naphthols by employing BF3‧OEt2 as a catalyst. This method features spiro-aziridine ring-opening (Friedel-Crafts type C–C bond formation) with concomitant dehydrative formal [3+2] cycloaddition leading to the formation of a complex and diverse benzoindoline fused spiro-oxindoles in moderate to good yields with wide substrate scope. Moreover, this protocol provides an avenue for the generation of a library of bioactive spiro-cyclic fused heterocyclic motifs which may prove to be of therapeutic interest.