Coupling of haloarenes to arenes has been facilitated by a diverse range of organic additives in the presence of KOtBu or NaOtBu since the first report in 2008. Very recently, we showed that the reactivity of some of these additives (e.g. compounds 6 and 7 in Figure 1) could be explained by the formation of organic electron donors in situ, but the role of other additives was not addressed. The simplest of these, alcohols, including 1,2-diols, 1,2-diamines and amino acids are the most intriguing, and we now report experiments that support their roles as precursors of organic electron donors, underlining the importance of this mode of initiation in these coupling reactions.