Total synthesis and NMR conformational study of signal peptidase II inhibitors, globomycin and SF-1902 A5

A stereoselective total synthesis of an antibiotic, globomycin (), and its congener, SF-1902 A5 (), was achieved. Two convergent macrocyclization routes via macrolactamization or macrolactonization to form are described. A conformational study by means of NMR spectroscopy was performed in several solvents. The 1H NMR spectrum of indicated that the amide proton of only the l-allo-Thr residue was involved in the hydrogen bonding. The structure in solution phase was different from the X-ray structure.