pentafluorobenzyl ( pfbz ) derivatives of the following nucleobases were prepared : cytosine , 5-methylcytosine , o2-methylcytosine , o2-ethylthymine , o4-ethylthymine , 5-hydroxymethyluracil , n6-methyladenine , o6-methylguanine , o6-hydroxyethylguanine and o6-hydroxyethylpurine .
C0010843
cytosine
C0049308
5-methylcytosine