1	DU3	2',5'-dideoxy-5'-[(diphenylmethyl)amino]uridine	1.000
2	DU4	2',5'-dideoxy-5'-[(diphenylmethyl)(methyl)amino]uridine	0.967
3	DUA	2',5'-dideoxy-5'-(tritylamino)uridine	0.829
4	DU2	2',5'-dideoxy-5'-{[(R)-(1-methyl-1h-imidazol-2-yl)(phenyl)methyl]amino}uridine	0.706