The stereoselective synthesis of β-configured C-allyl- and C-propargyl-d-arabinofuranosides (4,7-anhydro-1,2,3-deoxy-d-gluco-oct-1-enitols and -oct-1-ynitols) was addressed by employing allylation/propargylation of a dialdofuranose under aqueous Barbier reaction conditions and acid-catalyzed furan ring transposition of 5-O-mesyl-manno-oct-7-eno- or 5-O-mesyl-manno-oct-7-ynofuranoside derivatives.