Synthesis of three nucleoside building blocks with a benzoyl protected diam
inopurine (DAP) base and their incorporation at different positions of DNA,
RNA and hexitol oligomers (HNA) have been accomplished. DNA hairpins with
a DAP substituted for one (or more) adenine in the loop structure were not
found to be more stable. But the stability of RNA-hexitol as well as hexito
l-hexitol duplexes improved when the adenine base was replaced with DAP.