Semi-synthesis of A23187 (calcimycin) analogs

Summary The cleavage of A23187 to give a synthon (4) and the semi-synthesis from (4) of 2 Des-N-methylamino A23187 isomers (7a,b) are described. The antibiotic activities of the acids analogous to A23187(1), (2), (7a), (7b) are compared.Acknowledgment. The authors are very grateful to Drs G. Dauphin and J.Y. Lallemand for the NMR-spectra at 400 MHz performed in Gif-sur-Yvette, To Dr J.G. Gourcy and Mrs G. Kergomard for technical assistance.