p-Toluenesulfonic acid → HCID 131718825, compound

Participants

Reaction Steps

Condensation of Boc-trp-Leu-OH (part B of example of above-cited U.S. Pat. No. 4,472,305, 14.0 g.) and H-Phe-OBzl (freed from 14.33 g. of the p-toluenesulfonate salt with sodium bicarbonate) using dicyclohexylcarbodiimide (6.91 g.) and N-hydroxysuccinimide (3.86 g.) in tetrahydrofuran (250 ml.) at 0° C. for 1 hr. and then at room temperature overnight, isolation by ethyl acetate extraction, and purification by crystallization from methanol-ether-hexane gave Boc-trp-Leu-Phe-OBzl (16.9 g., 77% yield, m.r. 140°-142° C.).

Provenance & Evidence