Cobalt-Catalyzed Peroxidation of 2-Oxindoles with Hydroperoxides

Abstract

A highly efficient and facile cobalt-catalyzed C-H activation and peroxidation of 2-oxindoles was reported, which provides a new pathway for the synthesis of biologically active 3-peroxy-2-oxindoles from readily available starting materials in excellent chemical yields. The resulting products could be further transformed into various substituted 3-peroxyoxindoles in good to excellent yields. The developed method has been successfully applied to the synthesis of the natural product (±)-N-[2-(3-hydroxy-2-oxo-2,3-dihydro-1H-indol-3-yl)ethyl]acetamide.

Metal-Free C(sp3)–H Amination of 2-Oxindoles in Water: Facile Synthesis of 3-Substituted 3-Aminooxindoles

“…On the basis of the above-mentioned results and previous reports, ,,− a possible mechanism for the C­( sp 3 ) − H amination of 2-oxindoles is proposed in Scheme . Initially, t -BuO and t -BuOO radicals abstract hydrogen atoms from 2-oxindoles to afford radical A . , This strategy is supported by the isolation of 4 . , Then, in the presence of I + , the radical A was oxidized to a cation B through a single-electron-transfer process. , Finally, the nucleophilic reaction between 2 and B forms the amination product 3 . ,, …”

Direct Functionalization of C−H Bonds by Iron, Nickel, and Cobalt Catalysis

“…Recently, also the peroxidation of 2‐oxoindoles with hydroperoxides was reported. [Co(salen)] (salen= N , N ′‐ethylenebis(salicylimine)) proved to be the catalyst of choice and TBHP could be used as oxidant …”

“…[Co(salen)] (salen = N,N'-ethylenebis-(salicylimine)) proved to be the catalysto fc hoice and TBHP could be used as oxidant. [159] The most challenging field in CÀHa ctivation chemistry is the development of asymmetric transformations.A gain it was the group of Yoshikai which reported two such examples for Co-catalysis. [160,161] The first one in 2014 described an intramo-lecular hydroacylation of ketones and olefins using ab identate phosphine ligand.L ater,a ni ntermolecular variant of this transformation was reported as well.…”

C(sp3)–H Peroxidation of 3-Substituted Indolin-2-ones under Metal-Free Conditions

“…(3i) [2] , white solid (0.0812 g, 87% yield); 3-Hydroxy-3-phenylindolin-2-one (4d) [4] , white solid (32% yield)；…”