Copper-Catalyzed Selective ortho-C–H/N–H Annulation of Benzamides with Arynes: Synthesis of Phenanthridinone Alkaloids

Abstract

An efficient and convenient copper-catalyzed method has been developed to achieve direct ortho-C-H/N-H annulation to synthesize phenanthridinones with arynes. This method highlights an emerging strategy to transform inert C-H bonds into versatile functional groups in organic synthesis and provides a new way to synthesize phenanthridinone alkaloids efficiently.

Electrochemical Synthesis of 5‐Aryl‐phenanthridin‐6‐one by Dehydrogenative N,C Bond Formation

“…General synthetic approaches rely on metal‐assisted catalysis, such as Pd,–,, Ni, or Cu catalysts, organic mediators, radical initiators, or photocatalysis‐employing Ir‐complexes . These routes are accompanied by severe disadvantages such as harsh conditions, the necessity for additives or complex ligands, leastwise stoichiometric mediators, bases or oxidizers, leaving groups or elaborated precursors.…”

A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

“…The use of arynes was reported in 2017 by Zhang, with a Cu-based catalytic system. 399 o -(Trimethylsilyl)aryl triflates were employed as aryne precursors and the reaction offered access to phenanthridinones by means of an annulation process ( Scheme 66E ). The use of arynes is not common in C–H arylation processes, and this reaction is therefore a very interesting contribution to the field.…”

Copper‐Mediated Direct Cyanatation of Benzamides: A New Approach to the Synthesis of Quinazolinediones

“…It can also be observed from Table that the presence of strong electron‐donating group, such as methoxy group, decreased the reactivity of the reaction (Table , 2j and 2l ). Furthermore, when the reaction was performed with the substrates bearing meta‐substituted aryl rings, cyanatation was occurred at the less hindered C‐H bond with high regioselectivity (Table , 2k and 2l ) …”