HCID 67852048, compound → HCID 131710328, compound

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Reaction Steps

The reaction solution containing pyroglu-his azide, prepared as described in Example 22, is cooled to a temperature of -40°C., and to this is added a solution of 1.1 g. of trp-ser-tyr-OMe trifluoroacetate, as prepared in Example 4, 5, 6 and 7, in 4 ml. of degassed dimethylformamide. The pH of the resulting solution is adjusted to 8.0 by the addition of diisopropylethylamine, and the mixture is maintained at a temperature of -5°C. (with periodic adjustment of the pH to 8.0 by addition of diisopropylethylamine) for a period of 18 hours, at the end of which time the reaction to form the pentapeptide is substantially complete as shown by thin layer chromatography on silica gel G using the solvent system ethyl acetate-pyridine-acetic acid-water (10:5:1:3). The reaction solution is evaporated in vacuo; the residual material is dissolved in 50 ml. butanol; the butanol solution is washed with three 25 ml.-portions of water; the combined water washings are extracted with six 10 ml.-portions of butanol; and the combined butanol solutions are evaporated to a small volume. The crystalline material which precipitates is recovered by filtration, dried and further purified by chromatography on a silica gel column to give 0.5 g. of substantially pure pyroglu-his-trp-ser-tyr-OMe.

Provenance & Evidence