Site-selective installation of C−Me bonds remains a powerful and sought-after tool to alter the chemical and pharmacological properties of a molecule. Direct C−H functionalization provides an attractive means of achieving this transformation. Such protocols, however, typically utilize harsh conditions and hazardous methylating agents with poor applicability toward late-stage functionalization. Furthermore, highly monoselective methylation protocols remain scarce. Herein, we report an efficient monoselective, directed ortho-methylation of arenes using N,N,N-trimethylanilinium salts as noncarcinogenic, bench-stable methylating agents. We extend this protocol to d 3 -methylation in addition to the late-stage functionalization of pharmaceutically active compounds. Detailed kinetic studies indicate the rate-limiting in situ formation of MeI is integral to the observed reactivity.
A ruthenium-catalysed C–H arylation procedure that utilises a range of green solvents in place of the undesirable solvent NMP is presented. Examples of fast reaction time, low catalyst loading and large-scale reactivity are also shown.
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