Studies on New Antitumor Antibiotics, Leptofuranins A, B, C and D. II. Physicochemical Properties and Structure Elucidation.

The structures of new antitumor antibiotics, leptofuranins A, B, C and D were elucidated to be as shown in Fig. 1 by NMR spectral analysis including a variety of two-dimensional techniques. The leptofuranins are novel leptomycin-related substances containing a tetrahydrofuran ring. Leptofuranins C and D were revealed to be in tautomeric isomerism and their relative stereochemistries were analyzed by NOESY experiments.