L-Serine methyl ester

N-[N-(benzyloxycarbonyl)-L-aspart-l-oyl-(L-alanyl-L-threonyl-L-leucyl-L-alanine p-nitrobenzyl ester)-4-oyl]-N-[N-(benzyloxycarbonyl)-L-aspart-l-oyl-(L-alanyl-L-threonyl-L-leucyl-L-alanyl-L-serine p-nitrobenzyl ester)-4-oyl]-N-[N-(benzyloxycarbonyl)-L-aspart-1 -oyl-(glycine ethyl ester)-4-oyl -N-[N-(benzyloxycarbonyl)-L-aspart-l-oyl-(glycyl-L-serine methyl ester)-4-oyl]-... 

N-(tert-butoxycarbonyl)-L-aspart-1 -oyl-(L-phenylalanyl-L-serine methyl ester)-... 

L-Serine methyl ester can be transformed into methyl oxazolidin-2-one-3-carboxylate with phosgene and aqueous potassium carbonate (90TL7407). Some AAs (Gly, Val, Phe) were transformed into their iV-(2-chloroethylcar-bamoyl) derivatives, and these can cyclize into oxazolines (Scheme 24) (83T2255). In boiling water they are transformed into hydantoin derivatives. 

Hoechst has reported an enantioselective approach toward the key azabicyclo[3.3.0] octane-3-carboxylic acid 46 that preserves the stereochemistry of the L-serine-derived starting material (Urbach and Henning, 1991). L-Serine methyl ester (48) was alkylated... 

N-[(1,1-Dimethylethoxy)carbonyl]-L-serine methyl ester L-Serine, N-[(1,1-dimethylethoxy)carbonyl]-, methyl ester (9) (2766-43-0)... 

Y. Du and F. Kong, Stereoselective glycosidic coupling reactions of fully benzylated 1,2-anhydro sugars with W-tosyl-L-serine methyl-ester or iV-benzyloxycarbonyl-L-serine methyl-ester, J. Carbohydr. Chem., 14 (1995) 341-352. 

First the carboxylic acid 10 reacts with the amino group of the amino acid L-serine methyl ester 44. This reaction is carried out with DCC 45 and DMAP 46 as activators of the carboxyl group.20,21 With the basic DMAP 46 as the catalyst, a proton transfer between the carboxylic acid 10 and the diimide 45 yields the carboxylate anion 47 which undergoes nucleophilic addition to the protonated diimide 48. This activated ester 49 is readily attacked by the amino group of L-serine methyl ester 44 as a nucleophile. 

The hydroxy group of L-serine methyl ester does not undergo reaction with the activated ester 49 because of its smaller nucleophilicity. 

Stem bromelain is able to interact with two or more sequential amino adds in a peptide substrate, demonstrated by using A -benzyloxycarbonyl-L-phenylalanyl-L-serine methyl ester [36]. A glutamic add residue in position P3 prevents cleavage of the susceptible peptide braid. The sequences containing negatively charged residues in position P3 and P4 remain intact [37]. 

B. 3-(1,1-Dimethylethyl) 4-methyl-(S)-2,2-dimethyloxazolidine-3,4-dicarbox-ylate (3). To a solution of N-Boc-L-serine methyl ester (10.0 g, 45.6 mmol) in acetone (165 mL) is added 2,2-dimethoxypropane (50 mL, 400 mmol) and boron trifluoride etherate (BF3-OEt2, 0.35 mL, 2.8 mmol) (Notes 9 and 10). The resulting orange solution is stirred at room temperature for 2.5 hr when TLC analysis indicates the reaction to be complete (Note 11). The reaction mixture is treated with 0.9 mL of 99% triethylamine and the solvent is removed under reduced pressure. The residual brown syrup Is partitioned between diethyl ether (150 mL) and saturated aqueous sodium bicarbonate solution (250 mL). The aqueous layer is extracted with diethyl ether (2 x 150 mL) and the combined organic phases are dried with anhydrous sodium sulfate and concentrated under reduced pressure (7 mm and 65°C bath temperature) to give 10.4-10.8 g (88-91% crude yield) of oxazolidine methyl ester 3 as a pale yellow oil (Note 12). Analysis of crude 3 by 1H NMR indicates a chemical purity of > 95%. The product can be used without further purification. 

N-[(1,1-Dimethylethoxy)carbonyl]-L-serine methyl ester L-Serine,... 

First the carboxylic acid 10 reacts with the amino group of the amino acid L-serine methyl ester 44. This reaction is carried out with DCC 45 and DMAP 46 as activators of the carboxyl groiip. ... 

C12H15N05 N-carbobenzyioxy-L-serine methyl ester 1676-81-9 25.00 1.2347 2 24313 C12H17N02 4-butoxyacetanilide 23563-26-0 25 1 0506 31... 

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