To further demonstrate the potential of this operationally facile approach to introduce allyl functional groups, we wondered whether paraformaldehyde-d2 could be used in the HWE step. Such a straightforward, regioselective introduction of deuterium atoms in organic molecules would be of tremendous importance for mechanistic, spectroscopic and tracer studies. Using our two-step flow protocol, the analogous deutero-allylated compound 4-d 2 was isolated in 68% yield, perfectly matching the results obtained for the non-deuterated version 4.