Abstract: The invention relates to nucleo-side derivatives with photo-unstable protective groups of the general formula (I) ##STR1## in which R.sup.1 is H, NO.sub.2, CN, OCH.sub.3, halogen, alkyl or alkoxyalkyl with 1 to 4 C atoms, R.sup.2 is H, OCH.sub.3, R.sup.3 is H, F, Cl, Br, NO.sub.2 or an aliphatic acyl radical with 2 to 5 C atoms, R.sup.4 is H, halogen, OCH.sub.3, an alkyl radical with 1 to 4 C atoms or a possibly substituted aryl radical, R.sup.5 is H or a conventional functional group for producing oligonucleotides, R.sup.6 is H, OH, halogen or XR.sup.8, where X is O or S and R.sup.8 is a conventional protective group in nucleotide chemistry, B is adenine, cytosin, guanine, thymine, uracil, 2,6-diaminopurin-9-yl, hypoxanthin-9-yl, 5-methylcytosin-1-yl, 5-amino-4-imidazol carboxylic acid amid-1-yl or 5-amino-4-imidazol carboxylic acid amide-3-yl, where, if B is adenine, cytosin or guanine, the primary amino function may have a permanent protective group.

Abstract: The invention relates to nucleoside derivatives having photolabile protective groups of the general formula (I) ##STR1## in which R.sup.1 .dbd.H, NO.sub.2, CN, OCH.sub.3, halogen or alkyl or alkoxyalkyl having 1 to 4 C atomsR.sup.2 .dbd.H, OCH.sub.3R.sup.3 .dbd.H, F, Cl, Br, NO.sub.2R.sup.4 .dbd.H, halogen, OCH.sub.3, or an alkyl radical having 1 to 4 C atomsR.sup.5 .dbd.H or a usual functional group for preparing oligonucleotidesR.sup.6 .dbd.H, OH, halogen or XR.sup.8, where X.dbd.O or S and R.sup.8 represents a protective group usual in nucleotide chemistry,B=adenine, cytosine, guanine, thymine, uracil, 2,6-diaminopurin-9-yl, hypoxanthin-9-yl, 5-methylcytosin-1-yl, 5-amino-4-imidazolcarboxamid-1-yl, or 5-amino-4-imidazolcarboxamid-3-yl, where in the case of B=adenine, cytosine or guanine, the primary amino function optionally exhibits a permanent protective group.These derivatives may be used for the light-controlled synthesis of oligonucleotides on a DNA chip.