Tautomycetin 1, an antifungal agent from Streptomyces griseochromogenes shows a distinctive biological and structural similarity to tautomycin 2, which is known as a potent inhibitor of protein phosphatases (PP) type 1 and 2A. Although inhibitory activity of 1 to PP was not reported, it strongly suggests that 1 is also an inhibitor of PP1 and PP2A and that the structural difference of 1 and 2 is exchangeable. In order to obtain pertinent data for this hypothesis and to develop a specific inhibitor for PP1, we studied a total synthesis of 1 and conformational analysis of right fragments of 1 and 2. Biological activities of tautomycin analogs were also examined. The right half of tautomycetin were constructied by asymmetric crotylboration as key reactions. Efficient construction of dienone moiety has been achieved by a regioselective hydrostannylation of internal alkyne and the subsequent Stille coupling. Thus, two large subunits 3, 4 for synthesis of 1 were synthesized. Both molecular mechanics calculations and ^1H-NMR data exhibited that tautomycetin right half is present as "bent conformers". Most populated conformer of the tautomycetin right half showed a distinct similarity to the one found in the right half of tautomycin. Effects of tautomycin and its derivatives on protein phosphatases PP1 and PP2A and their apoptosis-inducing activity on human leukemia Jurkat cells were examined and the relationship between chemical structure and function was discussed.