Cyanamide mediated syntheses under plausible primitive earth conditions. I. The synthesis of P1, P2 dideoxythymidine 5'-pyrophosphate.

When an aqueous solution (pH 7.0) of deoxythymidine 5'-phosphate, 4-amino-5-imidazolecarboxamide and cyanamide was dried and heated for 18 h at 60 degrees C, P1, P2-dideoxythymidine 5'-pyrophosphate (I) was formed in a 58% yield. Oligonucleotides were not detected in the reaction product. Under conditions employed in the above reaction, (I) was shown to be stable. In prebiotic polymerization reactions employing deoxythymidine 5'-triphosphate as the polymerizing species, (I) could therefore function as a primer and minimize the formation of cyclic nucleotides.