Cesium fluoride → Acetic acid 2-((4aS,4bR,5S,6aS,6bS,9aR,10aS,10bS,12S)-4b,12-difluoro-5-hydroxy-4a,6a-dimethyl-2-oxo-8-phenyl-2,4b,5,6,6a,7,8,9,9a,10,10a,10b,11,12-tetradecahydro-4aH-8-aza-pentaleno[2,1-a]phenanthren-6b-yl)-2-oxo-ethyl ester

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Reaction Steps

In a nitrogen atmosphere compound 20 (150 mg, 0.300 mmol) is suspended in Acetonitrile (4 ml). 2-(trimethylsilyl)phenyl trifluoromethanesulfonate (0.146 ml, 0.600 mmol) and CsF (182 mg, 1.200 mmol) are added and the mixture is stirred for 45 minutes at RT. Additional CsF (137 mg, 0.900 mmol) (not dried) is added and the mixture is stirred for 5 hours then it is poured in water. Acetonitrile is evaporated and the reaction mixture is partitioned between water and AcOEt. The organic layer is separated dried over Na2SO4 and concentrated. The crude is purified by silica gel flash chromatography (eluent DCM/MeOH 98/2) affording the title compound (49 mg, 0.091 mmol, 30.3% yield).

Provenance & Evidence