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Phenol Derivatives in Ruthenium‐Catalyzed C–H Arylation: A General Synthetic Access to Azole‐Based Congested Polyaromatics
Author(s) -
Roger Julien,
Hierso JeanCyrille
Publication year - 2018
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201800312
Subject(s) - aryl , ruthenium , chemistry , electrophile , catalysis , combinatorial chemistry , reactivity (psychology) , allylic rearrangement , azole , medicinal chemistry , organic chemistry , antifungal , medicine , alkyl , alternative medicine , dermatology , pathology
Aryl triflates and related phenolates are suitable electrophile coupling partners for the ruthenium‐catalyzed direct arylation of heteroaromatic substrates using azole N‐directed C sp² –H activation. We report herein convenient conditions for the efficient ortho ‐C–H functionalization of aryl‐pyrazoles, thiazoles and pyridines in which [RuCl 2 ( p ‐Cym)] 2 precatalyst is employed with pivalic acid (PivOH) as co‐catalyst. Different phenolate derivatives were successfully coupled, which tolerate a large scope of electron‐rich substituents in para ‐, meta ‐ and highly hindered ortho ‐position. Electron‐withdrawing aryl triflates were found to be less reactive, making the general reactivity of these electrophiles complementary to those of aryl chlorides and deactivated bromides. This cost‐effective ruthenium C–H activation/arylation synthesis of poly(hetero)aromatics was concurrently examined using triflates, mesylates, sulfonates, and carbonates, and was also successfully extended to the use of diethyl carbonate as an eco‐friendly solvent.