Acid treatment of the hydroperoxide 5 yielded the enol ether 9. Hydrogenation of 9 gave the dihydro derivative, the structure of which was established by comparisonwith the substance synthesized by a different route. White, Martinelli, and Lancini have succeeded in the isolation of rifamycin W (l_) by using a mutant strain of Norcardia mediterranei, and have shown that washed mycelium from a rifamycin B producing strain of Norcardia mediterranei transformed rifamycin W into rifamycin B (2). 1,2,3,4 1 : rifamycin W 3.4 2 : rifamycin B They have suggested that rifamycin W is a normal intermediate in the biosynthesis of the other rifamycins, and further that a common progenitor is involved in the biosynthesis of the ansamycin antibiotics containing a naphthalene moiety such as rifamycins, streptovaricins, tolypomycins, and halomicins. 5 Related to our investigations on the synthesis of rifamycin S, 6 we were interested in examining the possibility to utilize a compound similar to rifamycin W as an intermediate for a chemical synthesis. A straightforward explanation for the transformation of rifamycin W (l_) into rifamycin B (2) would involve the following sequence of reactions:
In this communication, we would like to demonstrate the feasibility of this sequence, at least of its last half, using a model system.