L Leucine, methyl ester, hydrochloride

L-Leucine methyl ester hydrochloride (obtained from the Mann Research Laboratories, Inc.) was recrystallized from a mixture of methanol and ether. The recrystallized salt melted at 149-150°. 

Lead, tetrakis(acetato)- [-], 59,147 L-Leucine, methyl ester, hydrochloride [7517-19-3],56, 89 N- [A - [(phenylmethoxy)carbonyl] -L-phenylalanyl] -, methyl ester [3850-45-1],56, 93... 

Lead tetraacetate, 55, 44, 115 L Leucine, methyl ester, hydrochloride,... 

Peptide formation with an A-protected, optically pure aminocarboxylic acid is an alternative means of obtaining diastereoisomeric derivatives of chiral aminoalkylphos-phonic acids, the diastereoisomeric products being distinguishable on a quantitative basis by P NMR spectroscopy for example, A-boc-L-alanine was used to distinguish the enantiomers of diethyl (a-aminobenzyl)phosphonate. The reaction between an enan-tiomerically enriched sample of 125 (R = H) and L-leucine methyl ester hydrochloride in the presence of DCC was followed by HPLC separation of the l,l- and D,L-peptides 126 (R = H ratio 95.3 4.7), and essentially the same procedure was applied to an analysis of 125 (R = OCH2Ph), as prepared using the bislactim ether procedure (see Section IV. C.2.b) when the final product consisted of a mixture of R,S and S,S diastereoisomers in the ratio 87.4 12.6 ... 

Diphenyl phosphoryl azide in dimethylformamide followed by triethylamine added at or below 0° to a soln. of N-carbobenzoxy-L-leucyl-L-leucine and L-valyl-L-phenylalanine methyl ester hydrochloride in the same solvent, stirred several hrs. at the above temp, and overnight at room temp. -> product. Y 87%. - Practically no racemization occurred. F. e., also direct prepn. of urethans from carboxylic acids (cf. Synth. Meth. 17, 393) by a simplified Curtius degradation, s. T. Shioiri, K. Ninomiya, and S. Yamada, Am. Soc. 94, 6203 (1972) Tetrah. Let. 1973, 2343 synthesis of N-subst. carboxylic acid amides and peptides with diethyl phosphoryl cyanide s. Tetrah. Let. 1973, 1595 coupling reagents in peptide synthesis, review, s. Y. S. Klausner and M. Bodansky, Synthesis 1972, 453 review of peptide synthesis s. J. Meienhofer, Chem. Technol. 3, 242 (1973). 

The monomer was synthesized into 2 step process and the preparation process is described elsewhere [88]. In brief, the reaction mixture of L-leucine, thionyl chloride (SOCI2), methanol (MeOH) at -10 °C was brought to room temperature after stirring for 15 h. After completion of reaction, methanol and excess thionyl chloride were removed by distillation under reduced pressure and the residue was crystallized from diethyl ether. After filtered and dried under vacuum, (5)-leucine methyl ester hydrochloride was obtained as a white powder which was suspended into ethyl acetate (EtOAc), and triethylamine (EtsN) was dropwise added, stirred over 10 min, and collected by suction filtration. Maleic anhydride dissolved into ethyl acetate was added into the filtrate at room temperature, stirred over 24 h. The mixture was washed by H2O, saturated brine, and dried over Na2S04, and concentrated to obtain (S)-maleamic acid-L-leucine methyl ester ((5)-MLMA) as white powder. 

N,0-Dimethyl hydroxyl amine hydrochloride Methylamine, N-methoxy-, hydrochloride (8) Methanamine, N-methoxy-, hydrochloride (9) (6638-79-5) N-Methylpiperidine Piperidine, 1-methyl- (8,9) (626-67-5) N-tert-Butoxycarbonyl-L-leucine hydrate Leucine, N-carboxy-, N-tert-butyl ester, L- (8) L-Leucine, N-[(l,l-dimethylethoxy)carbonyl]- (9) (13139-15-6)... 

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