Only catalytic amounts of amine are required, with no increase in yield observed with stoichiometric amounts of DABCO (Entry 5, Table ). Due to the low extinction coefficient of the EDA complex, 50 mol% of the inexpensive catalyst proved optimal, especially for less reactive substrates. The reaction favoured polar aprotic solvents, with DMF providing yields comparable to DMSO (Entry 6, Table ), while protic or less polar solvents significantly reduced the yield (Supplementary Section 3).