Versatile Synthesis of 2,2‐Disubstituted Indolinones via Protected Indolones Generated by One‐Pot Multi‐Oxidation of 2‐Substituted Indoles.

Abstract

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Dearomative ipso-Cyclization to Spiropseudoindoxyls: An Extendable Approach To Access Indolo[3,2-c]quinolinones and Isocryptolepine

“…The spiropseudoindoxyl structural motif is an essential component of numerous natural products and pharmaceutically active molecules as a privileged heterocyclic scaffold displaying biological significance. , Specifically, C2-spiropseudoindoxyl-pyrrolidines are of particular interest, as these frameworks constitute the valuable architecture of various bioactive natural alkaloids ( I to III , Figure ). Owing to their wide range of biological activities, C2-spiropseudoindoxyl-pyrrolidines attracted the attention of synthetic chemists for their preparation, and a good number of synthetic strategies have been developed involving intramolecular cascade annulations, transition-metal-catalyzed intermolecular annulations, and dearomatization of indoles. − The latter approach is predominantly appealing due to the easy accessibility of starting materials, which broadly fall into two types: (i) 2,3-disubstituted (fused) indoles and (ii) 2-substituted indoles . Among these, the oxidative rearrangement via dearomatization/Wagner–Meerwein-type 1,2-shift from C3 to C2 of tetrahydro-γ-carbolines (2,3-disubstituted indoles) is one of the frequently used methods to construct the C2-spiropseudoindoxyl-pyrrolidines (Scheme a).…”