2', 3'-0 isopropylidene-5-ammomethyl uridine was condensed with some aldehydes. in the şame time, reduçtion 44in situ” of the reaction products was achieved Ncvçrtheless, the resulting compounds showed to be unstable during chromatographic processes. It was neces- sary, to increase their stability by suitable protection of their exo amino groups. On the other side, reactions concerhing both of 5-formyl uridine derivative with some halides, and 5-chlo- romethyl derivative of uridine with the previous aldehydes were also performed via Grignard reactions.