N-Benzyloxycarbonyl-

N-Benzyloxycarbonyl-L-aspartic acid-a-p-nitrophenyl, /3-benzyl Diester Hydrogen... 

A solution of 88.5 parts of L-phenylalanine methyl ester hydrochloride in 100 parts of water is neutralized by the addition of dilute aqueous potassium bicarbonate, then is extracted with approximately 900 parts of ethyl acetate. The resulting organic solution is washed with water and dried over anhydrous magnesium sulfate. To that solution is then added 200 parts of N-benzyloxycarbonyl-L-aspartic acid-a-p-nitrophenyl, -benzyl diester, and that reaction mixture is kept at room temperature for about 24 hours, then at approximately 65°C for about 24 hours. The reaction mixture is cooled to room temperature, diluted with approximately 390 parts of cyclohexane, then cooled to approximately -18°C in order to complete crystallization. The resulting crystalline product is isolated by filtration and dried to afford -benzyl N-benzyloxycarbonvI-L-aspartyl-L-phenylalanine methyl ester, melting at about 118.5°-119.5°C. 

To a solution of 180 parts of -benzyl N-benzyloxycarbonyl-L-aspartvI-L-phenylalanine methyl ester in 3,000 parts by volume of 75% acetic acid is added 18 parts of palladium black metal catalyst, and the resulting mixture is shaken with hydrogen at atmospheric pressure and room temperature for about 12 hours. The catalyst is removed by filtration, and the solvent is distilled under reduced pressure to afford a solid residue, which is purified by re-crystallization from aqueous ethanol to yield L-aspartyl-L-phenylalanine methyl ester. It displays a double melting point at about 190°C and 245°-247°C. 

Lipase-catalyzed methanolysis of racemic N-benzyloxycarbonyl (Cbz) amino acid trifluoroethyl esters carrying aliphatic side chains afforded the L-methyl esters and the D-trifluoromethyl esters (Figure 6.16). The released alcohol (CF3CH2OH) is a weak nucleophile that cannot attack the ester product. The nucleophilidty of the leaving group is depleted by the presence of an electron-withdrawing group [63]. 

N -(benzyloxycarbonyl)- ethyl L-Jysine benzyl ester chloroformote... 

N-Benzyloxycarbonyl-L-methionine was obtained from Bachem, Inc., 3132 Kashiwa Street, Torrance, California 90505. 

N-Benzyloxycarbonyl-L-methionine L-Methionine, N-carboxy-, N-benzyl ester (8) L-Methionine, N-[(phenylmethoxy)carbonyl]-(9) (1152-62-1)... 

Removal of N -Benzyloxycarbonyl Groups from Sulfur-Containing Peptides BY Catalytic Hydrogenation in Liquid Ammonia O-tert-BurvL-L-SERYL-S-... 

REMOVAL OF N -BENZYLOXYCARBONYL GROUPS FROM SULFUR-CONTAINING PEPTIDES BY CATALYTIC HYDROGENATION IN LIQUID AMMONIA O-tcrf-BUTYL-L-SERYL-S-tert-BUTYL-L-CYSTEINE ferr-BUTYL ESTER... 

Triethylamine (8) Ethanamine, N,N-diethyl- (9) (121-44-8) N-Benzyloxycarbonyl-O-te/t-butyl-L-seryl-S-Iert-butyl-L-cysteine fm-butyl ester ( —)... 

In order to test the influence of the C-terminus protecting groups on the properties of the resulting polymer, the ethyl, hexyl, and palmityl esters of N-benzyloxycarbonyl-L-tyrosyl-L-tyrosine were synthesized and the corresponding polymers (poly(CTTE),... 

Based on these monomeric building blocks a series of four structurally related poly(iminocarbonates) were synthesized carrying either no pendant chains at all [poly(Dat-Tym) ], a N-benzyloxycarbonyl group as pendant chain [poly(Z-Tyr-Tym)], a hexyl ester group as pendant chain (poly(Dat-Tyr-Hex) ], or both types of pendant chains simultaneously (poly(CTTH)] (Fig. 7). 

Subsequently, this mode of synthesis was extended to the preparation of similar derivatives.22-29 For example, the groups of Tsukamoto,25 Hough,26 and Yoshimura28 reported the synthesis of 2-acetamido-N-(L-aspart-l-oyl)-2-deoxy-/ -D-glycopyranosylamine (13) by coupling 8 with 4-benzyl N-(benzyloxycarbonyl)-L-aspartate30 (12) in the presence of DCC, followed by O-deacetylation, de-esterification, and hydrogeno-... 

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