p-Toluenesulfonic acid → 17-Ethyl-1-hydroxy-12-[2'-(3",4"-dihydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo[22.3.1.04,9]octacos-14,18-diene-2,3,10,16-tetraone

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A solution of 17-ethyl-1,14-dihydroxy-12-[2'-(4"-hydroxy-3"-hydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy- 13,19,21,27-tetramethyl-11,28-dioxa-4-azatricyclo-[22.3.1.04,9 ]octacos-18-ene-2,3,10,16-tetraone (210 mg) and a catalytic amount of p-toluenesulfonic acid in 40 ml of benzene was refluxed for 4 hours under a nitrogen atmosphere. The solvent was removed under reduced pressure and the dark residue was purified by chromatography (silica gel, 7% i-propanol/CH2Cl2) to give 17-ethyl-1-hydroxy-12-[2'-(4",3"-dihydroxycyclohexyl)-1'-methylvinyl]-23,25-dimethoxy-13,19,21,-27-tetramethyl-11,28-dioxa-4-azatricyclo-[22.3.1.04,9 ]octacos-14,18-diene-2,3,10,16-tetraone (180mg) as a white solid. This material was dissolved in ethanol (20 ml) and treated with 5% Rh/C (40 mg). Hydrogen was introduced via balloon for 30 min. and the mixture was filtered through celite. Removal of solvent followed by chromatography (silica gel) gave 172 mg of the title compound. Mass, 1H and 13C NMR data were consistent with the title structure.

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