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Show 81 Table 16\1 Observed Rotational Strength, Normalized Rotational Strength and Predicted y Value for Some Substituted Pyrimidine Nucleosides Substituent ROA(ob) x 10.,.40 'Ymax I N ROA x 10+20' y 0 C -H 5 261 9 9 16 Cs-CH3 267 50S 507 10 C5-B-7 279 4\11 S05 8 .CS-I 283 200 301 4 C -OH S 280 3\13 303 3 0 0 0 0 0 (N) =1206 20 +(Refo 64) 24 6 0 (N)s Sol esembles gratifying to observed that Figure It is portion of the R-y plot for compounds X and that this segment "is located between the (see Figure 4012)0 of X and XI a curve curves very similar to for X (cn = 3-, 4= predicted R=y plot =55°) and XI ( cn or 5= = cn 00 = a for all non- C-6 substituent intermediate between the +550) since the anti con- It would appeart therefore, suD,stituted pyrimidine nucleosides protonated and tautomeric 4D and corresponding segments and, possibly formation is centered about that for Xl· of Sect10n furanosyl nucleosides without rigid pyrimidine is The typical a forms the rotational semiquantitatively predicted by extrapolating strength from and their could be Figure 5lo |
