Table 1.

¹H–¹H and ¹H–¹⁹F Coupling Constant Values for Different Nucleoside Derivatives at 25 °C in D₂O (500 MHz)

J (Hz) (±0.2)a	2′,4′-diF-araU (7)	2′-F-araU (1)	2′,4′-diF-rUc
H1′–H2″b	6.0	4.0	0
H1′–F2′	8.5	17.5	21.5
H2″–H3′b	5.5	3.0	5.8
H3′–F2′	23.5	21.5	22.1
H3′–X4′	18.0	5.0	20.7

^aX = H for 2′-F-araU; X = F for 2′,4′-diF-araU and 2′,4′-diF-rU.

^bThe proton and the fluorine are labeled as ′′ and ′, respectively, regardless of the relative orientation.

^cRef 17.