N-alkylation of thymine and uracil with trialkyl phosphates

Treatment of thymine and uracil under appropriate conditions with trimethyl, triethyl. or tri-n-butyl phosphate has given 1-methylthymine (80%). 1,3-dimethylthymine (87%), 1 -ethylthymine (80%), 1-n-butylthymine (40%), 1-methyluracil (80%), 1,3-dimethyluracil (75%), and 1-ethyluracil (35%).