Hydrochloric Acid → Fmoc-leucine

To a mixture consisting of 19.4 g. of L-leucine, 15.7 g. of sodium carbonate, and 500 ml. of water, cooled to 0° C., is added a solution of 19.1 g. of 9-fluorenylmethylchloroformate in 200 ml. of tetrahydrofuran, and the resulting mixture is stirred at 0° C. for one hour and at room temperature for 15 hours. The mixtue is then acidified with 3 N hydrochloric acid and concentrated to remove the solvent. The residue is extracted with ethyl acetate, and the extract is washed with 100 ml. of 10% hydrochloric acid and with 100 ml. of water, dried, and evaporated to dryness to give a residue of N-9-fluorenylmethoxycarbonyl-L-leucine, which is slurried with n-hexane, isolated, and dried; m.p. 76°-79° C.; [α]D25 -28.7° (1.01% in methanol). To a mixture consisting of 15.2 g. of this intermediate product, 37 g. of pentachlorophenol, and 300 ml. of N,N-dimethylformamide, cooled to 5° C., is added 9.8 g. of dicyclohexylcarbodiimide, and the resulting mixture is kept at 4° C. for 2 days. It is then filtered, and the filtrate is evaporated to dryness to give a residue of N-9-fluoroenylmethoxycarbonyl-L-leucine pentachlorophenyl ester, which is triturated with n-hexane, isolated and dried; m.p. 119°-121° C.; [α]D25 -35.4° (1.00% in methanol).

1. additionis added a solution of 19.1 g
2. concentrationconcentrated
3. customto remove the solvent
4. extractionThe residue is extracted with ethyl acetate
5. washthe extract is washed with 100 ml
6. dry with materialof water, dried
7. customevaporated to dryness

ORD record

ord-0fd10a5c1f394b8b99a8cb75d134d918

Source dataset

uspto-grants-1978_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04128540