Preparation of 5-Benzyloxytryptophan: 11 grams α-acetylamino-β-(5- benzyloxy-indolyl-3)-propionic acid was suspended in a solution of 12 grams sodium hydroxide in 90 ml water and refluxed for 24 hours. Charcoal was added to the resultant solution and the mixture filtered hot. 150 ml 2N hydrochloric acid was added to the filtrate at 70°C and 5-benzyloxytryptophan crystallized on cooling. After washing with water and drying in vacuo over silica gel, the amino acid (6.9 grams, 71%) had MP (sealed evacuated tube) 232°C, with softening, finally melting at 237° to 238°C (decomposition). Charcoal was added to the filtrate, which was filtered hot and adjusted to pH 2. On cooling a second crop of 5-benzyloxytryptophan was obtained (2.2 grams, 23%), MP (sealed evacuated tube) 230°C, with softening, finally melting at 233° to 237°C (decomposition). The overall yield of 5- benzyloxytryptophan was 9.1 grams (94%).
