The synthesis of ribose and ribose-based nucleotides under reasonable
prebiotic conditions has not been achieved. Glycerol has been suggeste
d as a structural unit that might have preceded ribose in the evolutio
nary emergence of RNA. Template-directed oligomerizations of nucleotid
e analogs based on glycerol, however, have been only partially success
ful. Recent studies on the effect of ultraviolet irradiation of formal
dehyde solutions have shown that the reduced sugar pentaerythritol is
formed with great specificity. I argue that pentaerythritol is potenti
ally capable of being converted by simple chemistry into a series of n
ucleoside analogs related to barbituric acid. These analogs may be abl
e to take part in nucleic acid-like interactions and could therefore b
e of potential interest as a new class of candidates as RNA precursors
.