Aspartic acid 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. 

Alternatively, oxazolones have been used as reagents to activate and to couple N-protected dicarboxylic amino acids wherein the carboxylate moiety acts as the nucleophile. For example, 2,4-dimethyl-5(4//)-oxazolone 255 reacts with N-benzyloxycarbonyl-L-aspartic acid to give a mixture of the anhydrides 256 and 257. Subsequent reaction of 256 and 257 with phenylalanine methyl ester hydrochloride and A-methylmorpholine produces a mixture of the a-isomer 258 and p-isomer 259 of Al-benzyloxycarbonyl-aspartylphenylalanine methyl ester (Scheme 7.83). °... 

Dimethylnaphthalene A -Benzyloxycarbonyl-DL-aspartic acid A-Carbobenzoxy aspartic acid Aquafen... 

Labetalol HCI 4-Benzyloxyanillne HCI Hydroxytryptophan N-Benzyloxycarbonyl-L-aspartic acid-Ct-nitrophenyl,0-benzyl diester Aspartame... 

Proteases - Proteases have been applied to several synthetic purposes the most Important of which are peptide bond synthesis and protein semisynthesis. Recent extensive reviews cover this area. Prote-ases have been used in ester synthesis and resolution. Semisynthesis of human insulin has been achieved by enzymic removal and replacement of one amino acid in porcine insulin. All peptide bonds in the N-termlnal octapeptide of dynorphln [H-Tyr-Gly-Gly-Phe-Leu-Arg-Arg-Ile-OH] have been formed using proteases.A precursor of aspartame has been made by themolysin-catalyzed condensation of benzyloxycarbonyl-L-aspartic acid and L-phenylalanlne methyl ester. 

In recent years numerous attempts were made to apply enzymes for the systematic building of peptide chains and some of these syntheses were fairly successful . For instance the artificial sweetener, aspartame could be prepared without blocking the jS-carboxyl group of aspartic acid. In the thermolysine catalyzed reaction between benzyloxycarbonyl-L-aspartic acid and L-phenyl-alanine methyl ester, used in excess, at pH 7 the equilibrium is shifted to the right... 

The reaction of A -benzyloxycarbonyl aspartic acid anhydride 61 and Ni(COD)bpy under the reaction conditions used for succinic anhydride (THF, 23 °C, 6 h) failed to give the desired nickelacycle, although the oxidative addition took place as indicated by the dark red suspension formed upon mixing. Acid hydrolysis yields //-bencyloxycarbonyl-L-aspartic acid exclusively. When the reaction is carried out in refluxing THF, an equimolecular mixture of a- and P-alanines (Z-L-a-Ala-OH and Z-P-Ala-OH) is obtained, as a result of a nonselective oxidative addition (Scheme 24 and Table 1, Entry 1). 

Feng Y, Klee D, Hocker H (2002b), Synthesis of poly[(lactic acid)-a/t- or co-((s )-aspartic acid)] from (35, 6R,5)-3-[(benzyloxycarbonyl)methyl]-6-methylmorpholine-2,5-dione , Macromol. Chem. Phys., 203 (5-6), 819-824. 

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