Waste Minimized Multistep Preparation in Flow of β-Amino Acids Starting from α,β-Unsaturated Carboxylic Acids

An efficient protocol for the synthesis of beta-amino acids starting from easily accessible alpha,beta-unsaturated carboxylic acids based on the combination of two heterogeneous catalytic systems is reported. This multistep approach is based on the direct beta-azidation of alpha,beta-unsaturated carboxylic acids and subsequent azido group reduction performed in flow conditions. It has been demonstrated that the catalysts can be easily recovered and reused conserving its complete efficiency. The green metrics calculations proved the high environmental efficiency of the protocol characterized by very low waste production.