Oxiranecarbonitrile in basic aq. soln. at room temp. reacts regioselectively with inorg. phosphate to give the cyanohydrin of 2-oxoethyl phosphate ('glycolaldehyde phosphate'), a source of (the hydrate of) the free aldehyde, preferably in the presence of formaldehyde. In aq. phosphate soln. buffered to nearly neutral pH, oxiranecarbonitrile produces the phosphodiester of glycolaldehyde as its bis-cyanohydrin in good yield. In contrast to mono- and dialkylation, trialkylation of phosphate with oxiranecarbonitrile is difficult, and the triester deriv. is highly sensitive to hydrolysis. Glycolaldehyde phosphate per se is of prebiotic interest, since it has been shown to aldomerize in basic aq. soln. regioselectively to rac-hexose 2,4,6-triphosphates and in the presence of formaldehyde mainly to rac-pentose 2,4-diphosphates with, under appropriate conditions, rac-ribose 2,4-diphosphate as the major reaction product. However, the question as to whether oxiranecarbonitrile itself has the potential of having been a prebiol. natural constituent remains unanswered. Backbone structures of hexopyranosyl-oligonucleotides with phosphodiester linkages specifically between the positions 6' -> 4', 6' -> 2', or 4' -> 2' of the sugar residues can formally be derived via the (hypothetical) aldomerization pathway, a combinatorial intermol. aldomerization of glycolaldehyde phosphate and bis(glycolaldehyde)-phosphodiester in a 1:1 ratio. The constitutional relationships revealed by this synthetic anal. has played a decisive role as a selection criterion in the pursuit of exptl. studies toward a chem. etiol. of the natural nucleic acids' structure. The discussion delineates how the anal. contributed to the conception of the structure of p-RNA. [on SciFinder (R)]