Method for attachment of the first residue to Wang resin: In a typical experiment, Wang resin (10 g, 0.74 mmol hydroxylmethyl group/g) and Fmoc-amino acid (14.7 mmol, 2 eq) are shaken in 50 ml DMF at r. t. for 15 minutes. Pyridine (2 ml, 3.3 eq) and 2,6-dichlorobenzoyl chloride (2.1 ml, 2 eq) are added successively and the suspension is shaken for 15 - 20 h. The resin is filtered and washed with methylene chloride. Any remaining hydroxyl groups of the resin are then benzoylated with benzoyl chloride (3 ml) and pyridine (3 ml) in dichloroethane (80 ml) for 2 hours. The resulting resin is filtered, wahed with DCM, DMF and methanol, and dried under vacuum. The final substitution rate can be determined photometrically from the amount of Fmoc chromophore released upon treatment of the resin with piperidine/DMF.

Attachment of the Fmoc-amino acid on 2-chlorotrityl chloride resin: In a typical experiment, Fmoc-amino acid (6 mmole) and DIEA (4.4 ml, 25 mmole) are dissolved in dry dichloromethane (100 ml). A small amount of DMF is added if the acid is not completely dissolved in DCM (just enough to facilitate dissolution of the acid). The resulting solution is added to 2-chlorotrityl chloride resin (10 g, 1.1 - 1.6 mmole/g). The suspension is stirred for other 20 minutes. Subsequently methanol (10 ml) is added, and stirring is continued for other 10 minutes. The resin is filtered, washed (with 3 x DCM, 2 x DMF, 2 x methanol), and dried in vacuum. The final substitution rate can be determined photometrically from the amount of Fmoc chromophore released upon treatment of the resin with piperidine/DMF. For long term storage of the pre-loaded resin, the Fmoc group should be removed as it has been found to be more stable in the basic form.