TABLE 2.

Coupling constants (in Hz) for ¹H NMR data of 2,3-dideoxy-2,3-difluoro sugars 9, 12 and nucleosides 20–23 with d-arabino-configurations

	3J (H,H)				3J (H,F)
	1,2 or 1′,2′	2,3 or 2′,3′	3,4 or 3′,4′	4,5a/4,5b or 4′,5′a/4′,5′b	H1,F2 or H1′,F2	H3,F2 or H3′,F2	H2,F3 or H2′,F3	H4,F3 or H4′,F3	Others
9	<0.8	0.91	4.11	n.d.	10.03	19.76	13.44	22.60	4J 3,1 = 0.91
12	<1.0	<1.0	3.24	4.5/4.69	10.57	17.49	12.21	24.14	gemJ 2,F2 = 48.17 gemJ 3,F3 = 51.0 gemJ H5a,H5b = 12.71
20	3.97	2.17	3.76	4.27/4.85	17.67	15.29	12.82	24.80	5J F2′,H8 = 2.3 4J 1′,F3′ = 1.86 gemJ 2′,F2′ = 50.52 gemJ 3′,F3′ = 51.24 J H5′a,H5′b = 12.8
22	4.76	3.35	4.73	4.78	14.54	16.58	14.77	22.31	5J F2′,H8 = 2.27 4J 1′,F3′ = 0.9 gemJ 2′,F2′ = 50.86 gemJ 3′,F3′ = 52.16
21	2.42	2.74	3.90	5.04/4.98	15.04	15.90	14.0	21.16	gemJ 2′,F2′ = 49.70 gemJ 3′F3′ = 51.70 gemJ H5′a,H5′b = 12.8
23	3.24	3.37	4.32	6.30/5.26	15.11	15.39	17.06	20.44	gemJ H5′a,H5′b = 2.29 gemJ 3′,F3′ = 52.35 gemJ 2′,F2′ = 50.28