Trifluoroacetic acid → (6aR,7S,9aS,11S,13aS)-2,3,6,6a,7,8,9,9a,10,11,12,13-dodecahydro-11-hydroxy-6a,7,10,10-tetramethyl-3-oxo-5-diphenoxyphosphinyloxy-1H-benzo[8,8a][1]benzopyrano[2,3-e]isoindole

Participants

Reaction Steps

To a solution of the above Compound (56a) (256 mg, 0.36 mmol) in 2.5 ml of dry dichloromethane were added 50 μl of anisole and 2.5 ml of trifluoroacetic acid, and the mixture stirred for 10 min at the same temperature, and then for one hour at room temperature. The reaction mixture was concentrated under reduced pressure. The residue was made basic with 7% aqueous sodium hydrogen carbonate solution, and extracted with ethyl acetate. The extract was washed with water, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The residue was purified by a column chromatography (silica gel 15 g; ethyl acetate) to give 203 mg (91%) of Compound (57a).

Provenance & Evidence