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SEM Deprotection

(BF3-OEt2)






Examples:

Example 1



A solution of the SM (300 mg, 0.493 mmol) in DCM (7.5 mL) was cooled to 0 C and treated with BF3-OEt2 (0.243 mL, 1.97 mmol). The reaction mixture was stirred at 0 C for 2 h, then RT for 2 h. Additional BF3-OEt2 (0.122 mL, 0.986 mmol) was added and the mixture was stirred another 1 h. The reaction mixture was quenched with sat aq NaHCO3 and then concentrated in vacuo. MeOH was added and the mixture was stirred at RT for 24 h. The mixture was diluted with H2O and extracted with DCM (2x). The combined organics were dried (MgSO4) and concentrated in vacuo to give a white residue. The residue was purified by Prep LC (40 g silica, 0-10% MeOH/DCM) to give 141 mg of a white solid. The solid was dissolved in THF (10 mL) and 1N NaOH (1 mL) and stirred at RT for 17 h. The mixture was diluted with H2O and extracted with 5% MeOH/DCM. The combined organics were dried (MgSO4) and concentrated to give 75 mg of a white solid. The solid was purified by Prep LC (12 silica, 0-10% MeOH/DCM) to provide the product as a white solid. [64 mg, 27%]


[Patent Reference: WO2015144799, page 330, (18.8 MB)]


Example 2



To a solution of the SM (0.85 g, 1.8 mmol) in DCM (10 mL) at 0 C was added BF3-OEt2 (2.33 mL, 18.4 mmol). The reaction was allowed to warm to RT and stir for 2 h. The mixture was diluted with DCM (25 mL) and washed with aq 2M Na2SO4 (25 mL). The resulting slurry of white solid was filtered through celite. The layers were separated and the org layer was concentrated in vacuo. To the resulting residue was added dioxane (20 mL) followed by aq 2M Na2CO3 (20 mL, 40 mmol). The mixture was stirred at RT for 72 h, then was partitioned between EtOAc (50 mL) and H2O (50 mL). The layers were separated and the org layer was washed with brine (50 mL), dried (Na2SO4), and concentrated. The resulting material was purified on silica gel (50-100% EtOAc/heptane) to provide the product as a white solid. [0.14 g, 23%]


[Patent Reference: WO2012149280, page 63, (4.1 MB)]