An experimental investigation into the kinetics and mechanism of the aza-Michael additions of dimethyl itaconate

The aza-Michael addition is a versatile reaction for the modification of α,β-unsaturated carbonyl compounds with amines. The reactivity of dimethyl itaconate as a bio-based Michael acceptor is explored in this work. Through its reactions with piperidine and dibutylamine, it was found that the order of reaction can be changed by the choice of catalyst, solvent, or the concentration of the amine reactant. The effectiveness of catalysts was proportional to their Lewis acidity. Competitive isomerisation of dimethyl itaconate into unreactive regioisomers can be suppressed using low-polarity solvents and lower temperatures. This investigation of the aza-Michael additions of dimethyl itaconate has clarified the possible reaction mechanisms and optimised the protocol, supporting further use of this reaction in small molecule synthesis and modification of polymers.