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Several fungal strains, namely Bauveria bassiana, Cuninghamella echinulata, Aspergillus fumigatus, Penicillium crustosum and Cladosporium herbarum, were used as biocatalysts to resolve racemic mixtures of 1-aminoethanephosphonic acid using L/D amino acid oxidase activity. The course of reaction was analyzed by 31P-NMR in the presence of cyclodextrin used as chiral discriminating agent. The best result (42% e.e of R-isomer) was obtained with a strain of Cuninghamella echinulata.

Racemic and optically active N-phenylacetyl derivatives of 1-aminoethylphosphonic acid, 1-aminoethylphosphinic acid, and their mono- and diesters have been synthesized to study the substrate specificity of penicillinacylases.

N-Phenylacetylated derivatives of 1-aminoalkylphosphonic acids were synthesized and high enantioselectivity of their hydrolysis by penicillin acylase (EC 3.5.1.11) was demonstrated. Stereoselective enzymatic hydrolysis of racemic 1-(N-phenylacetylamino) alkylphosphonic acids was used for preparation of enantiomeric 1-aminoalkylphosphonic acids. The kinetic regularities of penicillin acylase catalyzed hydrolysis were established and the biocatalytic process was optimized to increase the optical purity and the yield of the optically active product.

Derivatives of α-amino acids with two stereogenic centers (cf.L-threonine) and di-, tri- and tetrapeptides are electrolyzed in MeOH or AcOH, with formation of N-acyl-N,O-acetals (1b - 15b, 20b), in an anodic oxidative substitution of the COOH by an OR group.The amine ends of the oligopeptides may be benzyloxycarbonyl(Z)- or (tert-butoxy)carbonyl(Boc)-protected.With unprotected dipeptides, an electrolytic decarboxylative cyclization to imidazolidinones (18c, 19c) may also occur (in H2O/NH4OAc).The electrolyses are carried out in simple flasks with cooling jackets ('undivided cell'), using constant current conditions and anodes of Pt or glassy C.The electrolyte is generated in situ by adding 10 - 20 mol-percent of a tertiary amine.Mild acidic hydrolysis of electrolysis products thus obtained may lead to amino-acid amides or peptide amides (10c, 11c, 12c, 17c) with one amino acid less than the starting material.The N,O-acetals from L-threonine and the oligopeptides also react with organometallic nucleophiles such as Grignard compounds (->21 - 26, 29), with formation of products in which the original COOH group has been replaced by alkyl or allyl (sometimes even with moderate stereoselectivity).By treatment of the peptide-derived (open-chain) N,O-acetals with trialkyl or triaryl phosphites/TiCl4, the RO group is replaced by a phosphodiester group in a (non-diastereoselective) Michaelis-Arbuzov-type reaction (1d, 1e, 2d - 9d, 5e).Thus, the two-step sequence of electrolysis and phosphonation converts an oligopeptide derivative to an analogue with a phosphonic-acid end group.The diastereoisomeric N-protected dimethyl and diethyl dipeptidephosphonates (also prepared from the corresponding diaryl esters by Ti(OR)4-mediated transesterification) could be separated by preparative HPLC (SiO2, Lichrosorb Si 60, 10 μm); the dextrorotatory isomers of 1d - 3d were assigned L,D-, the laevorotatory ones L,L-configuration by hydrolysis to and identification of the known amino and aminophosphonic acids.The results described demonstrate a new simple route leading, from a give oligopeptide, to pure peptide analogues of known configuration.

The synthesis of 1-aminoalkylphosphonous acids, isosteres of the protein amino acids, by addition of hypophosphorous acid to diphenylmethylimines is described.These analogues of glycine, alanine, valine, leucine, isoleucine, phenylalanine, tyrosine, tryptophan, serine, threonine, methionine, cysteine, cystine, glutamic acid, lysine, ornithine, arginine, and proline have been prepared and the analogues of alanine, valine, leucine, phenylalanine, and methionine resolved.The alanine, valine and methionine analogues have interesting antimicrobial activity and the alanine analogue has plant growth inhibiting properties.Oxidation of the appropriate 1-aminoalkylphosphonous acids gave the 1-aminoalkylphosphonic acid analogues of (+/-)-alanine, (-)-alanine, (+/-)-valine, (-)-valine, (+/-)-serine, (+/-)-threonine, (+/-)-lysine, (-)-leucine, and (+/-)-ornithine.