Dual Ligand-Enabled Nondirected C–H Cyanation of Arenes

Abstract

Aromatic nitriles are key structural units in organic chemistry and, therefore, highly attractive targets for C–H activation. Herein, the development of an arene-limited, nondirected C–H cyanation based on the use of two cooperatively acting commercially available ligands is reported. The reaction enables the cyanation of arenes by C–H activation in the absence of directing groups and is therefore complementary to established approaches.

Annulative π-Extension of Unactivated Benzene Derivatives through Nondirected C–H Arylation

“…Our study commenced with the nondirected approach using benzene ( 1a ), − which is underdeveloped as compared with the well-established directed syntheses. Cyclic diphenyliodonium salt ( 2a ) was employed as an aryl appending agent. ,− After extensive screening of palladium catalysts and reagents (see also the SI, section III), reaction conditions for the Pd-catalyzed 2-fold C–H activation relay were established to give 3aa in 65% yield (Table , entry 1) under acidic conditions.…”

Introduction to Spatial Anion Control for Direct C–H Arylation

“…The initial milestones in nondirected arene-limited olefination have been followed by the development of several other functionalization processes. Direct C-H cyanations of arenes were reported in 2019 by the groups of Ritter 62 and van Gemmeren, 63 who used the dual-ligand approach, 53 and Yu, 64 who used a modified 2-pyridone 52 ligand (Scheme 3). In 2019, the van Gemmeren group demonstrated the direct sterically controlled C-H alkynylation of arenes (Scheme 4).…”

Spot on: C‐H‐Aktivierung

“…So sind zwar grundsätzlich elektronenreiche Positionen begünstigt, aber bei einer Konkurrenz zwischen sterischer und elektronischer Kontrolle lassen sich die Positionen funktionalisieren, die nicht über klassische Aromatenchemie zugänglich sindalso die sterisch besser zugänglichen, und das selbst dann, wenn diese elektronisch benachteiligt sind. 8) Über dieses Katalysatordesign haben wir Methoden zur nichtdiri-gierten Funktionalisierung von Aromaten entwickelt: Olefinierungen zu (9) und (10), 9,10) Cyanierungen zu (11) und (12) 11) sowie Alkinylierungen zu (13) und (14). 12) Das Produkt (14) eignet sich besonders, um die Konkurrenz zwischen sterischer und elektronischer Kontrolle zu betrachten: Hier entsteht selektiv das Produkt, bei dessen Bildung die geringste sterische Hinderung auftritt.…”