Xylose‐DNA Containing the Four Natural Bases

Oligonucleotides containing (2′‐deoxy‐β‐D‐xylofuranosyl)guanine have been prepared. For this purpose 2‐aminoadenosine (5) was synthesized and converted to 2′‐deoxy‐β‐D‐xyloguanosine (1). The related 2′‐deoxy‐β‐D‐xyloisoguanosine (3) and 2′‐deoxy‐β‐D‐xyloxanthosine (4) were also synthesized. Compound 1 was converted to the phosphonate and phosphoramidite building blocks 10 and 11, respectively. The oligodeoxynucleotide (5′‐3′)d(xG‐xT‐xA‐xG‐xA‐xA‐xT‐xT‐xC‐xT‐xA‐xC‐T) (18) formed a duplex with the same Tm as the parent (5′‐3′)‐(G‐T‐A‐G‐A‐A‐T‐T‐C‐T‐A‐C) (19), but with an inverted CD spectrum.