The semi-synthesis of A. 23187 (calcimycin) analogs 14̃ bearing the respective substituents: 5-NH2, 5-NHCH3, 5-N (CH3) 2, 5-NHCOCH3 was carried out. The complexing properties of 14̃ for calcium and magnesium were determined by two-phase experiments (water/toluene- butanol 70: 30 W/W) and found to be much weaker than these of A. 23187 or X. 14885A. There was a discrepancy with theoretical predictions made from model ...
