Aminophosphonic acids natural

The last 25 years have seen very signihcant progress in the chemistry of formylphosphonates. - This chapter describes their preparation, their use in intermolecular and intramolecular Horner-Wadsworth-Emmons reactions, and, given their discovery in nature, their importance as precursors for aminophosphonic acids. 

Although initially prepared and evaluated as a racemate, the NMDA antagonist activity was likely to reside primarily in a single enantiomer. The stereoselective nature of the NDMA receptor is well established, albeit not completely understood. Consequently, several attempts have been undertaken to develop synthetic protocols that would allow preparation of optically active compounds. Early reports of preparation of optically active co-amino-o-carboxyalkylphosphonic acids describe the preparation of (.S )-A P-3 from an optically active amino nitrile prepared by reaction of diethyl 1-formylphosphonate with hydrogen cyanide and (5)-(-)-a-methylbenzylamine. Acid hydrolysis, enrichment of the diastereomers by fractional recrystaUization, and debenzylation lead to the isolation of (.S )-A P-3 in 86% enantiomeric excess. " Recently reported procedures, which use chemoenzymatic processes, offer a more convenient and mild approach for the production of optically pure aminophosphonic acids. Enzymatic hydrolysis of amides using penicillinacylase (EC... 

Aminophosphonic acids play an important role in living systems. The first acid to be found naturally, namely (2-aminoethyl)phosphonic acid (also known as ciliatine, 2AEPH, and jS-Ala ) , has been followed more recently by 2-amino-5-phosphonopent-2-enoic acid, isolated from Streptomyces plumbens, and (2-amino-l-hydroxyethyl)phosphonic acid, isolated from Acanthamoeba castellani and formed through the biological hydroxylation of (2-aminoethyl)phosphonic acid. Many acids are inhibitors of enzymes important in carboxylic acid biochemistry. Ala is a potent inhibitor of a racemase from Gram-positive bacteria (the corresponding phosphinic acid 99 is not). Phosphinothricin... 

Mention might also be included here of the nature and potential importance of the choice of amino-protection and ester groupings in work on the aminophosphonic acids. The choice of groups for protection at nitrogen is obviously based on experience in conventional amino acid chemistry, and both r rr-butyloxycarbonyl (boc) and benzyloxy-carbonyl (cbz) groups are extensively employed. Most recorded syntheses of aminoalkyl-phosphonic and -phosphinic acids have relied on diethyl or dimethyl esters, largely as a consequence of the ready availability of the simple trialkyl phosphites and dialkyl hydro-genphosphonates the same esters are also preparable under mild conditions from the free acids by the action of ortho esters RC(OR )3 (R = H or Me, R = Me or Until... 

The only naturally occurring aminophosphonic acid is (-)-l-aniino-2-(4-hydroxy-phenyl)ethylphosphonic acid. 

Excellent results were reported in asymmetric hydrophosphorylation of imines by heterobimetallic catalysts (Scheme 8.77) [193]. Although the yield and enantiomeric excess were affected by nature of the imine, solvent, temperature and catalyst, as high as 96% e.e. was achieved. The catalyst with potassium ions showed the best performance under studied conditions. This synthetic approach is of potential interest for industrial applications in the synthesis of chiral a-aminophosphonic acids [194]. 

In 1959, Horiguchi and Kandatsu discovered 2-aminoethanephosphonic acid (AEP) in ciliated sheep rumen protozoa [1], the simplest natural aminophosphonate. This acid is present in some organisms in remarkably high amounts. Freshly laid eggs contain over 95% of total phosphorus in the phosphonate form, principally as AEP [2]. 

Some new amidophosphoric acid esters containing substituted pyridine moieties have been synthesized and characterized by H, P H) NMR, IR, and mass spectrometry. The study, synthesis, and spectroscopic characterization of phosphonates has been well documented during 2008 and several papers are worthy of mention. Starting with a-aminophosphonates and on a green chemistry theme, three types of D,D-diethyl V-dehy-droabietic a-aminoaryhnethylphosphonates have been synthesized from natural product derivatives following a two-step, solvent-free reaction... 

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