Metal-Free C(sp³)–H Azidation in a Radical Strategy for the Synthesis of 3-Azido-2-oxindoles at Room Temperature

Abstract

A novel and environmentally attractive C(sp)-H azidation of 2-oxindoles involving the formation of a C-N bond was developed. This methodology achieved for the first time 3-azido-2-oxindole construction under metal-free conditions at room temperature via a radical strategy. PhI(OAc) was used as the oxidant and EtN was used as the additive in this transformation. Furthermore, the mechanistic study indicated that this azidation involved a radical process.

Potassium‐Persulfate‐Promoted Regioselective Azidation/Cyclization of 1,6‐Enynes

“…Finally, we added various additives such as 20 mol% of Cu(OAc) 2 and 2.0 equiv. of Et 3 N . However, no obviously change in the desired product yield was noted (entries 14–15).…”

Chiral Bifunctional Thiosquaramides as Organocatalysts in the Synthesis of Enantioenriched 3,3‐Disubstituted Oxindoles

“…Solvents were dried and stored over microwave‐activated 4 Å molecular sieves. Known compounds 1 ,[8a] 2 ,[8a] 5a – b , d , l , 5c , 5e , 5m , and 5n have been prepared as described in the literature.…”

Hypervalent iodine-mediated synthesis and late-stage functionalization of heterocycles

“…Further, radical-based strategy to prepare 3-azido-2-oxindoles 368 was developed by Chen et al via C(sp 3 )−H azidation of 3-substituted-2-oxindoles 366 (Scheme 99). 129 This transformation employs TMSN3 367 as the azide reagent in the presence of PhI(OAc)2 6 and Et3N as an oxidant and additive respectively. Notably, azidation reaction proceeds smoothly with 3-aryl-2-oxindoles whereas 3-alkyl-2-oxindole showed no reactivity.…”