The activation of readily available but poorly reactive alcohols can be carried out solely in the presence of the tert-butoxide (KO^tBu)/dimethylformamide (DMF) couple. This system allows the direct use of primary alcohols as alkylating agents to functionalize the C(sp³)–H bond of methyl azaarenes, in the absence of traditionally used transition metal-based catalysts. Various alkylated N-heteroarenes such as pyridine, quinoline, pyrazine or quinoxaline derivatives have been obtained by this method, which is supposed to proceed via the initial formation of an alkyl formate intermediate, as shown by experimental and theoretical mechanistic studies.