NEW COMPOUNDS OF THE MANUMYCIN GROUP OF ANTIBIOTICS AND A FACILITATEDROUTE FOR THEIR STRUCTURE ELUCIDATION

Manumycin B (2) and C (3) are structural analogs of manumycin A (1), t he main metabolite of Streptomyces parvulus (strain Tu 64). The new mi nor components vary within the polyketide assembling of the acylamino side chain and the stereochemistry at C-4 in the central mC7N unit. Ap art from unreported stereochemical details 2 and 3 resemble the recent ly found UCF1-A and -B, inhibitors of ras farnesyltransferase. Manumyc in D (4) is the first of the manumycin type compounds without an oxira ne in the mC7N unit. The relative stereochemistry in the mC7N unit of 2-4 was elucidated with proton NMR spectroscopy using different ASIS ( aromatic solvent induced shift) effects on the olefinic 3-H. In combin ation with the established circular dichroism (CD) spectroscopy the ab solute stereochemistry of the whole mC7N unit was determined without c hemical degradation.