Novel enamine derivatives of 5,6-dihydro-2'-deoxyuridine formed in reductive amination of 5-formyl-2'-deoxyuridine.

Reductive amination of 5-formyl-3',5'-di-O-acetyl-2'-deoxyuridine with primary amines and sodium triacetoxyborohydride (NaBH(OAc)(3)) afforded novel enamine derivatives of 5,6-dihydro-2'-deoxyuridine as a result of unexpected 1,4-conjugate reduction of intermediate Schiff bases in addition to the secondary amine derivatives of 2'-deoxyuridine, typical 1,2-reduction products.