Iridium-catalyzed Decarbonylative Coupling of Acyl Fluorides with Arenes and Heteroarenes via C-H Activation

Acid Fluorides in Transition‐Metal Catalysis: A Good Balance between Stability and Reactivity

“…As imilar strategy has been used for the decarbonylative methylation or ethylation of acid fluoride using Lewis acidic trimethyl-or triethylborane and ac losely related catalytic system (Ni(cod) 2 /dppe), which suffers from anarrower scope. [16] Thecontrol of reactivity and selectivity in organometallic catalysis is essential, and by careful tuning of the catalytic system and the reaction conditions,acid fluorides can evolve selectively in ad ecarbonylative or an on-decarbonylative pathway.T his crucial control of the CO release has been addressed in the palladium-catalyzed reduction of acid fluorides 1 with triethylsilane developed by Sakai and coworkers,w here the ligand fully controls the decarbonylation process (Scheme 7). An external source of fluoride (KF) is required to activate the B 2 pin 2 (10), while NaCl as an additive is essential to reach satisfactory yields of products 11.Acomparative experiment showed that benzoyl chloride is totally unreactive under these reaction conditions,i ndicating that the acid fluoride plays ac rucial role and that there is no conversion of the acid fluoride into the acid chloride with NaCl during the reaction.…”

Catalytic C−H/C−F Coupling of Azoles and Acyl Fluorides

“…Transition‐metal‐catalyzed cross‐coupling reactions of acyl electrophiles with aryl nucleophiles represent a powerful and reliable synthetic strategy for the introduction of acyl fragments into aromatic rings to provide aromatic ketones, and a large variety of carboxylic acid derivatives are currently used as acyl electrophiles . Among these, acyl fluorides have recently gained much attention as valuable carbon‐based electrophiles in cross‐coupling reactions, especially in acyl coupling and decarbonylative coupling reactions . Due to the moderate electrophilicity of acyl fluorides, they exhibit a good balance between stability and reactivity with respect to their compatibility under nucleophilic conditions, that is, they are more stable than the commonly employed acyl chlorides, yet more reactive than the corresponding esters and amides .…”

“…The use of ubiquitous aromatic compounds as nucleophilic fragments, that is, the direct coupling of acyl fluorides with unactivated arenes, could potentially offer an alternative and improved synthetic route to the same architectures (Scheme b). However, despite this prospective synthetic potential, the acylation of aromatic C−H bonds by acyl fluorides has not been explored to date, with several notable exceptions: the Friedel–Crafts type acylation…”

“…For all entries in Scheme , small amounts of the corresponding decarbonylative coupling products were also detected by GC‐MS method. Accordingly, we examined the corresponding decarbonylative side reaction between 1 a and 2 a to form 3′ , that is, a C−H arylation by an acyl fluoride, as a complementary strategy for the C−H acylation . As shown in Scheme , high temperatures (180 °C) facilitate the decarbonylation step, and the corresponding C−H arylation product 3′ was formed preferentially (56 % yield).…”

Säurefluoride in der Übergangsmetallkatalyse: Balance von Stabilität und Reaktivität

“…Die Reaktion verlief mit einer großen Auswahl an Säurefluoriden 4 und Boronsäuren 7 glatt in mittleren bis hervorragenden Ausbeuten. [16] Die Steuerung von Reaktivitätu nd Selektivitäti st in der metallorganischen Katalyse von entscheidender Bedeutung, und durch eine sorgfältige Anpassung des Katalysesystems und der Reaktionsbedingungen kçnnen Säurefluoride selektiv entweder über einen decarbonylierenden oder über einen nicht-decarbonylierenden Reaktionspfad reagieren. Ferner gelingt die Decarbonylierung mit beiden Nickelsystemen bei Raumtemperatur,w ährend mit Palladium hohe Te mperaturen bençtigt werden.…”