Abstract: 8, 2'-o-cyclo-Ara-A is the key intermediate for the synthesis of Ara-A. There is a few reports on the NMR of this compound, only H-1' chemical shifts and coupling constants were reported, but no ¹³C-NMR data reported. ¹H and ¹³C NMR spectra of 8, 2'-o-cyclo-Ara-A were assigned by ¹H-¹H COSY, ¹³C-¹H COSY and NOE-DIFFERENCE techniques. The conformation of sugar ring was further confirmed.

Key words: 8,2'-o-cydo-Ala-A, 2D-NMR, NOE-DIFFERENCE