Alanine ethyl ester hydrochloride, preparation

The solvent-free mechanochemical reaction of Ceo with ethyl 2-diazopropionate was investigated by Wang and coworkers [14], For this purpose, ethyl 2-diazopropionate was prepared in situ from alanine ethyl ester hydrochloride and reacted with fullerene. In the course of reaction, three products, methanofuUerene 27 and fulleroids 28 and 29 were obtained in 1.2 1 4.6 ratio (Scheme 7.7). When milling was carried out with preformed ethyl 2-diazopropionate, products 27-29 were obtained in 3.6 1 3.6 ratio and 27% yield. For comparison, reaction carried out in toluene for 16h at room temperature afforded 46% of compounds 27-29 in a ratio of 4 1 10. Although the pyr-azoline intermediate was not observed reaction is presumed to take place by initial 1,3-dipolar cycloaddition and subsequent nitrogen elimination from unstable pyrazo-line adduct. 

Stepwise Degradation to Amino Adds. There are several approaches to the transformation of a di- or poly-carboxylic acid to an amino acid. The most satisfactory procedure makes use of the ester acids and their salts. They react with hydrazine to form hydrazide acids, which may be degraded through the azide acids to amino acids. From substituted malonic esters a-amino acids are obtained. (For the preparation of a-amino acids from substituted cyanoacetic esters, see p. 359.) Thus, the potassium salt of the monoethyl ester of methylmalonic acid, which is prqjared by half hydroly of the diethyl ester, pves alanine ethyl ester hydrochloride in 67% yield. Many other amino acids have... 

Scheme 12.109. A preparation of P-alanine as the hydrochloride. The ethyl ester is prepared as usual with ethanol from the hydrochloride (after Moe, O. A. Warner, D. T. /. Am. Chem. Soc., 1949, 77,1251).

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