Amino acids linked to Polystyrene-2-chlorotrityl chloride resin. A very acid sensitive resin suitable for the synthesis of protected peptide fragments by the Fmoc strategy. Residues which are sensitive to racemisation during esterification reactions like His and Cys can be attached to the resin without racemisation. Due to the bulkiness of the trityl group, diketopiperazine formation is suppressed which makes this linker ideal for peptides with C-terminal Pro. This resin has also been used in the solid phase synthesis of ß-peptides via the Arndt-Eistert homologation of Fmoc-protected amino acid diazoketones. Cleavage from this resin is achieved for protected peptides by treatment either with AcOH/trifluoroethanol/DCM or 0.5% TFA in DCM or hexafluoroisopropanol. Free peptides are released with 95% TFA. Fmoc D-amino acids on request