Table 2.
Compound | 5′-O protection | 5′-C modification | 3 J H1′-H2′ (Hz) | % C3′ endoa |
---|---|---|---|---|
Guanosine | TBS | H | 5.3 | ∼50 |
(R) isomer, 5 | TBDPS | methyl | 6.6 | ∼30 |
(S) isomer, 15 | TBDPS | methyl | 5.3 | ∼50 |
aThe percent of molecules in the C3′-endo conformation was calculated as (100 – (10 × 3JH1′-H2′)) as previously described (52), where 3JH1′–H2′ is the 1H NMR coupling constant of the sugar H1′ and H2′ protons.