Investigation of the lipase-catalysed reaction of aliphatic amines with ethyl propiolate as a route to N-substituted propiolamides

The lipase-catalysed reaction of aliphatic amine with ethyl propiolate was investigated using benzylamine as reference amine. The conditions were optimised to favour the 1,2-addition, i.e., formation of N-benzylprop-2-ynamide, versus the 1,4-addition. Immobilised Candida antarctica lipase (CALB) was found to be the most efficient enzyme, and the reactions were performed in solvents, such as tBME, dioxane or toluene. The methods were used to prepare propiolamides from aliphatic amines in good to excellent yields. The reactivity of O- and S-nucleophiles was compared in the same conditions.