11-Acetyl-4-formyl-6,9-dihydroxy-14-oxa-1,11-diazatetracyclo[7.4.1.02,7.010,12 ]tetradeca-2,4,6-trien-8-ylmethyl carbamate (25 mg) was dissolved in tetrahydrofuran (2.5 ml) and the solution was added to a suspension of sodium hydride (60% in oil, 3 mg) in tetrahydrofuran (0.5 ml). To this mixture was added a solution of octanoyl chloride (12 μl) in tetrahydrofuran (108 μl) in an ice-water bath and the mixture was stirred for 1 hour in an ice-water bath. After stirring for 36 hours at room temperature, an additional amount of octanoyl chloride (50 μl) was added and the mixture was stirred for 3 hours at room temperature. The reaction mixture was then directly subjected to a preparative thin layer chromatography. Development was carried out with a mixture of chloroform and acetone (1:1, v/v) to afford 11-acetyl-8-carbamoyloxymethyl-4-formyl-9-hydroxy-14-oxa-1,11-diazatetracyclo[7.4.1.02,7.010,12 ]tetradeca-2,4,6-trien-6-yl octanoate (7 mg).
