ORGANOPHOSPHORUS COMPOUNDS AS POTENTIAL FUNGICIDES .3. PEPTIDE DERIVATIVES OF ALPHA-AMINOPROPANEPHOSPHONIC ACID

Di- and tri-peptides with alpha-aminopropanephosphonic acid as the aci d-terminal residue have been prepared containing L-alanyl, D-alanyl, D L-alanyl, and glycyl groups. Nmr parameters (H-1, C-13, and P-31) are reported for solutions of the peptides in D2O and are discussed. Diast ereoisomeric forms of the L-ala-, and L-ala-L-ala-peptides were separa ted on a cation exchange-column and it was found in each case that the methine and carbonyl groups of the alanyl residue that is adjacent to the aminophosphonic group exhibit slightly different C-13 chemical sh ifts in each of the two diastereoisomers. Fast-atom bombardment mass s pectrometry gave characteristic [MH](+) ions, which usually appeared a s the base peak. Fragment ions were formed by the elimination of alpha -lactam units from the amino-carboxylic acid residues and phosphorous acid from the aminophosphonic acid residue. The L-ala-peptides showed similar activity to that of alpha-aminopropanephosphonic acid when app lied as seed-dressings at 400 ppm for the control of Drechslera spp. G lycyl peptides were slightly less active but the D-ala-peptides had li ttle or no activity.