Rhodium(III)‐ and Iridium(III)‐Catalyzed C7 Alkylation of Indolines with Diazo Compounds

Abstract

A Rh(III)-catalyzed procedure for the C7-selective C-H alkylation of various indolines with α-diazo compounds at room temperature is reported. The advantages of this process are: 1) simple, mild, and pH-neutral reaction conditions, 2) broad substrate scope, 3) complete regioselectivity, 4) no need for an external oxidant, and 5) N2 as the sole byproduct. Furthermore, alkylation and bis-alkylation of carbazoles at the C1 and C8 positions have also been developed. More significantly, for the first time, a successful Ir(III)-catalyzed intermolecular insertion of arene C-H bonds into α-diazo compounds is reported.

Rhodiumkatalysierte sp2‐ und sp3‐C‐H‐Funktionalisierungen mit entfernbaren dirigierenden Gruppen

“…Die Selektivität der Reaktion wird durch die Nähe des C1‐H und der inkorporierten dirigierenden Gruppe gesteuert. Verschiedene Berichte über Rh III ‐katalysierte C1‐Funktionalisierungen mit einer Amid‐ oder einer Pyrimidyl‐dirigierenden Gruppe umfassen Heteroarylierungen, Alkylierungen, Cyanierungen, Allylierungen und Alkenylierungen (Tabelle ).…”

“…Durch die Umwandlung von Indol in Indolin wird die Möglichkeit einer C2‐H‐Funktionalisierung genommen und somit die Realisierung der selektiven C7‐Funktionalisierung ermöglicht. In der Tat konnten in den letzten Jahren unter Anwendung dieser Strategie eine Reihe von C7‐Funktionalisierungen von Indolin realisiert werden, darunter eine Alkenylierung, Alkylierung, Allylierung und Cyanierung (Tabelle ).…”

Alkynylation with Hypervalent Iodine Reagents

“…The pyrimidine ring was not only successful in the case of benzenes, but also for the functionalization of indoles. This methodology has also been used by Zhou and co-workers to alkynylate a more functionalized indole substrate [131]. Non-aromatic directing groups such as oximes, nitrones, nitrosoanilines, azo-or azoxy-groups and simple amides could also be used.…”

Rhodium(III)‐Catalysed Carbenoid C(sp2)–H Functionalisation of Aniline Substrates with α‐Diazo Esters: Formation of Oxindoles and Characterisation/Utility of an Intermediate‐Like Rhodacycle

“…Following the seminal work of Rovis et al, Cui and co‐workers developed a protocol for the synthesis of azepinone derivatives through the Rh III ‐catalysed C–H activation of benzamides with vinyl carbenoids . More recent reports of Rh III ‐catalysed C–H functionalisation using diazo compounds as coupling partners have come from the groups of Glorius, Wang, Chang, Xu and Yi, Liu, Zhou, Kim, Lee, Zeng, and Samanta . Although decent progress has been made in this area, we believe that such an interesting topic is worthy of further exploration.…”