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

Oxiranecarbonitrile in basic acqueous solution at room temperature rea cts 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 formaldeh yde. In aqueous phosphate solution buffered to nearly neutral pH, oxir anecarbonitrile produces the phosphodiester of glycolaldehyde as its b is-cyanohydrin in good yield. In contrast to mono- and dialkylation, t rialkylation of phosphate with oxiranecarbonitrile is difficult, and t he triester derivative is highly sensitive to hydrolysis. Glycolaldehy de phosphate per se is of prebiotic interest, since ii had been shown [5] to aldomerize in basic aqueous solution regioselectively to,nc-hex ose 2,4,6-triphosphates and - in the presence of formaldehyde - mainly to rac-pentose 2,4-diphosphates with, under appropriate conditions, r ac-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. B ackbone structures of hexopyranosyl-oligonucleotides with phosphodiest er linkages specifically between the positions 6'-->4', 6'-->2', or 4' -->2' of the sugar residues can formally be derived via the (hypotheti cal) aldomerization pathway, a combinatorial intermolecular aldomeriza tion of glycolaldehyde phosphate and bis(glycolaldehyde) phosphodieste r in a 1:1 ratio. The constitutional relationships revealed by this sy nthetic analysis has played a decisive role as a selection criterion i n the pursuit of our experimental studies toward a chemical etiology o f the natural nucleic acids' structure. The Discussion in this paper d elineates how the analysis contributed to the conception of the struct ure of p-RNA. The English Footnotes to Schemes 1-11 provide an extensi on of this summary.