To a solution of 6.2 g. of crystalline antibiotic X-537A in 125 ml. of methylene chloride was added 4.6 g. of silver oxide and 14 g. of methyl iodide. After stirring for 18 hours, the reaction mixture was filtered and the filtrate concentrated to 7.07 g. of a light yellow oil, which was decolorized with Darco, giving 6.09 g. of a colorless foam. A portion (4 g.) of the foam was chromatographed on a florisil column (150 g.) eluting with a gradient between methylene chloride (1 l.) to ether (1 l.) and then ether (500 ml.) to acetone (500 ml.). Rechromatography of the slightly yellow oil, recovered from the florisil column, on a 75 g. silica gel column and eluting with a gradient between methylene chloride (1 l.) and 15 percent ether/-methylene chloride gave 200 mg. of a clear viscous oil, Bp. 170°d/005 mm. [α] D25 -7.19° , (1.1 percent CH3OH).
