Reactivity trends for mechanochemical reductive coupling of aryl iodides

Abstract

Reductive coupling reactions are a facile and versatile way to make carbon–carbon bonds. However, most methods within this class of reactions makes use of reprotoxic, amide-based solvents. Mechanochemistry, a method that does not always require solvent, has been used for reductive coupling methods but still reports the use of at least some amide-based solvent for productive outcomes. This work presents the reactivity trends for the reductive homocoupling of aryl iodides when using various amounts of N,N-dimethylformamide (a commonly used amide-based solvent) and dimethyl carbonate (a greener alternative). The results of these experiments show that dimethyl carbonate may be used in sub-stoichiometric amounts with equal or greater efficiency to N,N-dimethyl formamide. Further, cross-electrophile coupling (XEC) is explored with various solvents, showing that N-butyl pyrrolidinone is efficient as a liquid assisted grinding solvent. These experiments show that under mechanochemical conditions, safer solvents are able to be used with no loss of efficacy for reductive coupling reactions.