The Ethylation of Nucleic Acid-Bases with Triethyl Phosphate

Uracil, thymine, cytosine, adenine, and guanine were alkylated by triethyl phosphate in a homogeneous aqueous phase at 60–80 °C, giving the corresponding ethyl derivatives in considerable yields. The reactivity order on the ethylating site in each base was found to be as follows; uracil, thymine, and cytosine: N-1>N-3; adenine: N-9≈N-3>N-7, N-1; guanine: N-1>N-7>N-3, N-9.