Functionalization aminocarboxylic acid

In today s discussion of the origin of life, the RNA World (Chapter 6) is seen as much more important, and is much better publicized, than the protein world . However, nucleic acids and proteins are of equal importance for the vital metabolic functions in today s life forms. Peptides and proteins are constructed from the same building blocks (monomers), the aminocarboxylic acids (generally known simply as amino acids). The way in which the monomers are linked, the peptide bond, is the same in peptides and proteins. While peptides consist of only a few amino acids (or to be more exact, amino acid residues), proteins can contain many hundreds. The term protein (after the Greek proteuein, to be the first) was coined by Berzelius in 1838. 

The reactions with formation of polymers also are classified based on another difference in their mechanism. This classification distinguishes step reactions and chain reactions. In step reactions the polymers are built from the monomer by random individual reactions to form dimers, trimers, tetramers, etc., each resulting molecule being able to participate in a subsequent reaction with a monomer or with an oligomer molecule. This type of reaction may start with molecules having two reactive functional groups in one molecule such as an o-aminocarboxylic acid. Another possibility consists of reactions between two different types of bifunctional molecules such as a diamine and a dicarboxylic acid as shown below ... 

An w-aminocarboxylic acid can react internally to form a macroring with one amide function. More often this type of starting material reacts to give 2 2 and 3 3 cyclization produets (Vellaccio et al., 1977). The larger products are partieularly evident where the 1 1 product would be a medium sized ring. 

The major chelating functions found in siderophores are catechol, hydroxyphenyloxazolone, hydroxamate, phenol, a-hydroxycarboxylic acid, a-aminocarboxylic acid, and thiazole (Tables 1 and 2). 

Functionalization of hydrocarbon groups of aminocarboxylic acids Persulfate lodonium betaines s. 18, 589... 

Selective reduction. A soln. of borane in tetrahydrofuran added dropwise at -18 during 19 min. to a mixture of adipic acid monoethyl ester and tetrahydrofuran, stirred and allowed to warm to room temp, during 16 hrs. -> ethyl 6-hydroxy-hexanoate. Y 75-88%. - Other functional groups such as cyano, halogeno, keto, or nitro, are likewise retained during this highly convenient reduction. F. e., also reduction of sterically hindered acids, s. N. M. Yoon, H. C. Brown et al., J. Org. Chem. 38, 2786 (1973) 2-aminoalcohols from a-aminocarboxylic acids s. M. L. Anhoury et al., Soc. Perkin 11974,191 via reduction with aq. NaBH of enolesters obtained from the acids and N-ethyl-5-phenylisoxazolium 3 -sulfonate (s. Synth. Meth. 16, 448) s. P. L. Hall and R. B. Perfetti, J. Org. Chem. 39, 111 (1974). 

One method consists of the synthesis of a monomer with a long alkyl substituent containing a terminal functional group in the first stage. A cholesterol group is added to the terminal functional group in the second stage. The cholesteryl esters of iV-acryloyl- and lV-methacryloyl-(0-aminocarboxylic acids have been obtained with this method [58-60] (see also Chapter 6). 

Generally, (n-amino-(n-(hydroxycarbonyl)alkylphosphonic acids are made by one of two general reaction classes, which can be differentiated by the stage at which the phosphorus-carbon bond is introduced. In this particular reaction the P-C bond formation may precede (Sections 8.1.10.1-3) or follow (Sections 8.1.10.4-6) the incorporation of the aminocarboxylic functional group. 

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