p-Toluenesulfonic acid → 5-(9-(9-Fluorenylmethyloxycarbonyl)aminoxanthen-2-oxy)valeric Acid

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Reaction Steps

A solution of p-toluenesulfonic acid (0.15 g, 0.8 mmol) in glacial acetic acid (3 mL) was added dropwise at 25° C. over 15 minutes to a well-stirred suspsension of 5-(9-hydroxy-xanthen-2-oxy)valeric acid (2.0 g, 6.4 mmol) prepared as described above and Fmoc-amide (1.84 g, 8.2 mmol) in glacial acetic acid (50 mL). This mixture was stirred continuously and then filtered after 3 hours to collect a white solid which was washed with water (3×20 mL) and ehtyl ether (3×20 mL). The solid was dried in vacuo over P2O5 at 25° C. Yield: 2.35 g(61%, m.p. 210-211° C., Rf : 0.53 EtOAc/MeOh 5:1. NMR data and elemental analysis in accordance with structure. ##STR12##

Provenance & Evidence