CHEMISTRY OF ALPHA-AMINONITRILES .13. FORMATION OF 2-OXOETHYL PHOSPHATES (GLYCOLALDEHYDE PHOSPHATES) FROM RAC-OXIRANECARBONITRILE AND ON (FORMAL) CONSTITUTIONAL RELATIONSHIPS BETWEEN 2-OXOETHYL PHOSPHATES AND OLIGO(HEXOPYRANOSYL AND PENTOPYRANOSYL) NUCLEOTIDE BACKBONES

Oxiranecarbonitrile in basic acqueous solution at room temperature reacts regioselectively with inorganic 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 aqueous phosphate solution 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 derivative is highly sensitive to hydrolysis. Glycolaldehyde phosphate per se is of prebiotic interest, since ii had been shown [5] to aldomerize in basic aqueous solution regioselectively to,nc-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 prebiological 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 intermolecular aldomerization of glycolaldehyde phosphate and bis(glycolaldehyde) phosphodiester in a 1:1 ratio. The constitutional relationships revealed by this synthetic analysis has played a decisive role as a selection criterion in the pursuit of our experimental studies toward a chemical etiology of the natural nucleic acids' structure. The Discussion in this paper delineates how the analysis contributed to the conception of the structure of p-RNA. The English Footnotes to Schemes 1-11 provide an extension of this summary.