racemic β-hydroxyaldehydes bearing a phosphonate group in the ω-position were synthesised and allowed to react with dihydroxyacetone phosphate (DHAP) via an enzymatic aldol addition catalysed by fructose 1,6-bisphosphate aldolase (FruA). After enzymatic dephosphorylation, a set of unnatural ω-phosphonic deoxysugars was obtained.