Iridium‐Catalysed Cascade Synthesis of Oxindoles Using Diazo Compounds: A Quick Entry to C‐7‐Functionalized Oxindoles

Abstract

A cascade iridium‐catalysed oxindole synthesis was achieved using pyridyl‐protected anilines and bis(2,2,2‐trifluoroethyl) 2‐diazomalonate. The developed protocol is simple and scalable, and has a broad scope and excellent regioselectivity. The pyridyl directing group can easily be removed. The method was further extended to give C‐7‐functionalized oxindole derivatives in a straightforward manner. The role of bis(2,2,2‐trifluoroethyl) 2‐diazomalonate for oxindole preparation has been explored.

Copper-Catalyzed Direct, Regioselective Arylamination of N-Oxides: Studies To Access Conjugated π-Systems

“…In continuation with our interest in directed C–H bond functionalizations, especially on the construction of quinoline N -oxide-based organic conjugated π-systems using earth abundant transition-metal catalysts, herein we report the syntheses of the C2-arylaminated quinoline and related heterocyclic N -oxides via their cross couplings with anthranils using the eco-friendly and economical copper catalyst (Scheme f).…”

Recent advances in transition-metal-catalyzed carbene insertion to C–H bonds

“…294 With dimethyl (1-diazo-2oxopropyl)-phosphonate as the carbene source compound 3indolylphosphonates were accessed in 59-75% yields. Other directing groups such as pyridyl, 295 ketone, 296 phosphine oxide, 297 and pyrazolyl 298 were also applied in iridiumcatalyzed intermolecular aryl C(sp 2 )-H functionalization by carbene insertion with diazo compounds. Under Ir(III) catalysis 2-(arylamino)pyridines (191) reacted with acceptor/acceptor diazo compound 260 in the presence of LiOAc in CF 3 CH 2 OH (TFE) to afford oxindole derivatives 261 in up to 72% yields (eqn ( 64)).…”

“…Under Ir(III) catalysis 2-(arylamino)pyridines (191) reacted with acceptor/acceptor diazo compound 260 in the presence of LiOAc in CF 3 CH 2 OH (TFE) to afford oxindole derivatives 261 in up to 72% yields (eqn ( 64)). 295 2-Pyridyl as the directing group enabled the further C-H functionalization at 7-position of oxindole 261a by switching the reaction conditions (eqn (65)), producing the enol-type products 262. Aryl alkyl ketones 263 reacted with 2diazotized Meldrum's acid (173) under the conditions similar to those shown in Scheme 80 293 to produce the alkylated ketone products 264 in moderate to excellent yields without occurrence of carbene insertion to the alkyl C(sp 3 )-H bonds (eqn (66)).…”

Straightforward Construction and Functionalizations of Nitrogen‐Containing Heterocycles Through Migratory Insertion of Metal‐Carbenes/Nitrenes

“…Our group developed an improved protocol for the direct synthesis of parent oxindole via Ir(III)-catalysed regioselective alkylation, cyclo-condensation, followed by decarboxylation (Scheme 5). [17] During the screening of the directing groups, pyridine was found to be the most effective for this transformation. Pyrimidine also delivered the desired product, albeit in poor yield.…”