8-Amino-dA and 8-amino-dG are useful in triplex formation due to the presence of the additional amino groups.
2'-DeoxyXanthosine (dX) is a naturally occurring nucleoside that may be derived from oxidative deamination of 2'-deoxyGuanosine (dG). dX has a similar bonding pattern to thymidine and it may base pair with dA, with such purine-purine interactions causing duplex distortion. dX also featured in attempts to extend the genetic alphabet with a new base pair of dX and pyrimidine-2,4-diamine nucleoside. dX has also interested researchers in the field of DNA damage and repair since it is a product of nitric oxide-induced mutagenesis.
Coupling: No changes needed from standard method recommended by synthesizer manufacturer.
Deprotection: No changes needed from standard method recommended by synthesizer manufacturer.