Abstract: The present invention relates to a process for the preparation of an oligomeric compound made up of two or more individual oligomers, in which said oligomeric compound the individual oligomers are separated by a photocleavable linker, comprising the step of photoactively cleaving said linker.

Abstract: The invention provides ribonucleoside derivatives with novel protecting groups and methods for the preparation of such ribonucleoside derivatives. The general formula (I) of the ribonucleoside derivatives is: wherein R1 is a base of the purine- or pyrimidine-family or a derivative of such a base or any other residue with serves as a nucleobase surrogate, R2 is a proton or a substituted derivative of phosphonic acid, R3 is a proton or a protection-group for the oxygen atom in 5?-position, R4, R5 and R6 are independently alkyl or aryl or a combination of alkyl and aryl or heteroatom, R4, R5 or R6 may also be cyclically connected to each other; and wherein at least one of the R4, R5 or R6 substituents comprises a tertiary C-atom or a heteroatom vicinal to the Si-atom.