Preparation of solid phase bound peptides or PNAs

A process for the preparation of at least one solid phase bound peptide, PNA or chimera having a sequence of interest with side chain functional groups comprising the steps

• a. immobilizing a starting sub-unit having a first protective group for the protection of the tail group on a first solid phase and one or more additional side chain protective groups for the protection of any side chain functional group if present in the sub-unit and subsequently deprotecting said tail group;
• b. coupling to the tail group of the previously immobilized sub-unit by an additional sub-unit bearing the first protective group for the protection of the tail group and one or more additional side chain protective groups for the protection of any side chain functional group if present in the sub-unit;
• c. blocking of unreacted tail groups of the previously immobilized sub-unit from step (b) with a capping group other than the first protective group;
• d. deprotecting the tail group bearing the first protective group;
• e. repeating steps (b) to (d) until completion of the sequence of interest;
• f. cleaving the peptide, PNA or chimera from the first solid phase under reaction conditions not affecting the capping group and not affecting at least one side chain protective group and immobilize the peptide, PNA or chimera via tail group without further purification on a second solid phase;
• and
• g. cleaving the one or more side chain protective groups after having immobilized the peptide, PNA or chimera on the second solid phase,
• wherein the tail group is an amino group.