Anhydrosugars
2.4
295
4 Anhydronucleosides
Several anhydronucleosides such as oxiranes 91 [58] or oxetanes 92 [59] ( > Fig. 21) inhibit
HIV replication.
⊡ Figure 21
Examples of anhydronucleosides
They are also useful intermediates in the preparation of biologically important compounds [60]
including unsaturated nucleosides. Several representatives of the latter compounds such as
3 -azidothymidine (AZT), 2 ,3 -dideoxyinosine (ddI), 2 ,3 -dideoxycytosine (ddC), and 2 ,3 -
dideoxy-2 ,3 -didehydro-thymidine (d4T) (see > Scheme 25) are approved as anti-HIV drugs
by the US Food and Drug Administration [1].
Nucleosides with conformationally restricted carbohydrate rings (locked nucleic acids—LNA)
are RNA mimics containing the 2 -O,4 -C-methylene linkage. The bicyclic structure locks
⊡ Figure 22
Synthesis of locked nucleic acids (LNA)
2.4
295
4 Anhydronucleosides
Several anhydronucleosides such as oxiranes 91 [58] or oxetanes 92 [59] ( > Fig. 21) inhibit
HIV replication.
⊡ Figure 21
Examples of anhydronucleosides
They are also useful intermediates in the preparation of biologically important compounds [60]
including unsaturated nucleosides. Several representatives of the latter compounds such as
3 -azidothymidine (AZT), 2 ,3 -dideoxyinosine (ddI), 2 ,3 -dideoxycytosine (ddC), and 2 ,3 -
dideoxy-2 ,3 -didehydro-thymidine (d4T) (see > Scheme 25) are approved as anti-HIV drugs
by the US Food and Drug Administration [1].
Nucleosides with conformationally restricted carbohydrate rings (locked nucleic acids—LNA)
are RNA mimics containing the 2 -O,4 -C-methylene linkage. The bicyclic structure locks
⊡ Figure 22
Synthesis of locked nucleic acids (LNA)