Copper/Diboron‐Mediated Intramolecular Oxygenation and Allylation/Benzylation of Nitroalkynes for the Synthesis of C2‐Quaternary Indolin‐3‐ones

Abstract

A direct strategy for intramolecular transfer oxygenation of alkynes and cycloisomerization of 2-nitroalkynes to synthesize a wide range of C2-quaternary indolin-3-ones was developed by a copper/diboron system. The desired allylation, benzylation and propargylation products were obtained in moderate to excellent yields with good functional group tolerance. The mechanism study indicated that this protocol involved a radical process.

Isatin and its derivatives: a survey of recent syntheses, reactions, and applications

“…22 However, in one study, a unique method employing a Cu/B2pin2 system for intramolecular oxygenation of alkynes has been reported (Scheme 5). 23…”

“…In addition, the isatin moiety in the two derivatives forms additional H-bond interaction with the hCA XII active site and thus might be responsible for the lower K i values of these derivatives against hCA XII compared to hCA IX. 66 A series of 2/3/4-[(2-oxo-1,2-dihydro-3H-indol-3-ylidene)amino]benzenesulfonamides (23) were evaluated as CA inhibitors and they showed interesting inhibitory profiles against hCA IX and hCA XII isoforms. Among these, the derivative with R 1 = CH 3 , R 2 = H, and o-substituted SO 2 NH 2 displayed the highest selectivity for the tumor-associated isozymes hCA IX and hCA XII over the cytosolic off-target isoforms hCA I and hCA II.…”

Gold‐Catalysed Nitroalkyne Cycloisomerization – Synthetic Utility

“…group employed different radical sources such as allyl, benzyl and propargyl bromides to synthesize diverse C2-quaternary indolin-3-ones 29 (Scheme 6). [14] Following this, Peng's group developed a CuH-catalysed reductive cyclization of o-alkynylnitroarene 30 for the diasterospecific synthesis of 3-hydroxyindoline 31 and 2-aryl-3Hindol-3-one scaffolds 32 in a one pot operation (Scheme 7). The standard catalytic operation involved treatment of 30 in the presence of CuCl 2 /dppf (ligand) (10 mol %) along with Me(EtO) 2 SiH/LiOMe (4 equiv.)…”