Benzhydrylamine-resin (40.44g 0.5 mmol/g, 20.22 mmol) was coupled with Boc Arg (Tos)-OH(34.6g, 80.7 mmol) in 25% DMF-CH2Cl2 with DCC (16.78g, 81.4 mmol) for 2h followed by the addition of 1% diisopropylethylamine and reacted for 0.5 h longer. The resultant Boc-Arg (Tos)-BHA-resin was washed with CH2Cl2 (3×250 mL), MeOH(3×250 mL), CH2Cl2 (3×250 mL) and dried. The couplings and washing procedures were repeated and an aliquot was hydrolyzed (1 mL of 6M propionic acid/HCl at 130° for 2 h). Amino acid analysis showed a substitution of 0.35 mmol of Arg per gram of resin. The remaining amino groups were acetylated with AC2 0-Pyridine. Yield 48.88g (Boc-Arg(Tos)-BHA-resin, 4).
