PURPOSE: To obtain new uridines substituted at the 5-position useful for producing, etc., oligonucleotides having the 5-position of thymine group bound to a labeling compound by reacting, etc., an arabinoaminoxazoline with dimethyl α-bromomethylfumarate.

CONSTITUTION: This method for producing the objective uridines, substituted at the 5-position and expressed by formula V [R is H or OH; X is NH2, NHC 0CF3, etc.; (n) is 2, 3, or 6] is to react arabinoaminoxazoline expressed by formula I with dimethyl (α-bromomethylfumarate expressed by formula II (Me is methyl), provide 2, 2'-anhydro-5-methoxycarbonylmethyluridine expressed by formula III, then react the resultant compound with acetyl bromide, afford 2'-deoxy-2'-bromo-3',5'-diacetoxy-5-methoxycarbonylmethyluridine expressed by formula IV, further reduce the prepared compound with tri-n-butyltin hydrlde, subsequently successively react the reduced compound with diamines and ethyl trifluoroacetate or treat the reduced compound with acetic anhydride/acetic acid, subsequently hydrolyze the treatment product and then successively react the resultant hydrolyzate with diamines and ethyl trifluoroacetate.