Methanol → (7S)-2,9,9-Trimethoxy-7beta-methyl-7,8,9,10-tetrahydrophenanthridine-6,10alpha-diol 6-(trifluoromethanesulfonate)

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Reaction Conditions

Reaction Steps

A solution of (S)-7,8-dihydro-2,9-dimethoxy-7-methyl-6-phenanthridinol trifluoromethanesulfonate (ester) (12, 3.00 g, 7.40 mmol, 1 equiv) and m-CPBA (5.10 g, 14.9 mmol, 2.00 equiv) in methanol (120 mL) was heated at reflux for 1 h. After cooling to 23° C., the reaction solution was partitioned between 1:1 saturated aqueous sodium bicarbonate solution:saturated aqueous sodium thiosulfate solution (200 mL) and dichloromethane (200 mL). The aqueous layer was separated and extracted further with dichloromethane (2×200 mL). The combined organic layers were dried over sodium sulfate and were concentrated. The residue was purified by flash column chromatography (25% ethyl acetate-hexanes initially, grading to 40% ethyl acetate-hexanes) away from structure 14 to afford (7S, 10R)-7,8,9,10-tetrahydro-2,9,9-trimethoxy-7-methyl-6,10-phenanthridinediol 6-(trifluoro-methanesulfonate) (13) as a yellow foam (2.12 g, 63%).

Provenance & Evidence