Studies on Nucleosides and Nucleotides. LXXXVIII. : Purine Cyclonucleosides. XLIII. : ¹³C NMR Spectra of 2'-Substituted 2'-Deoxyadenosines. Substituent Effects on the Chemical Shifts in the Furanose Ring System

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^<13>C nuclear magnetic resonance spectra of various 2'-substituted 2'-deoxyadenosines are presented. The relative substituent chemical shifts of each sugar carbon are analyzed in terms of a substituent electronegativity parameter and compared with the data for substituted cyclohexanes. The relative substituent chemical shifts of C_2' and C_4' are controlled mainly by the inductive effect of the substituent. Those of C_1' and C_3' cannot be interpreted by inductive effect only. Some effect which is perturbed by the presence of a cis-substituent seems to be operating. A good linear correlation was observed between the substituent chemical shift of C_2' and the N conformer population in the furanose puckering equilibrium.