On-the-fly H2 degassing: Towards selective borohydride reduction of α, β-unsaturated esters to allylic alcohols in continuous microflow

•A hybrid microflow system was developed for borohydride reduction.•α, β-unsaturated esters can be reduced to allylic alcohols safely and efficiently.•Methyl cinnamate was reduced to cinnamyl alcohol in an 85% yield in 75 s.•The kinetics of this reduction in microflow processes was examined and modelled.•The results shed new light on the development of continuous microflow processes.