Evaporation of the solvent afforded a 95:5 mixture (365 mg, 98% theoretical) of the two isomeric epoxides. A CHC13 solution (50 mL) of this mixture (365 mg) was treated with p-TsOH acid (3 mg) at room temperature for 18 h and worked up as described above. The reaction mixture (350 mg) was chromatographed on a silica gel H column eluted with EtOAc to yield compound 23 (294 mg, 82% theoretical): amorphous material (CHC13); mp

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