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Aldehyde to Difluoro



Example 1

To a suspension of the SM (150 mg, 0.302 mmol) in DCM (1.21 mL) was added DAST (0.100 mL, 0.754 mmol). The mixture was shaken at 50 C for 30 min, after which time a yellowish solution resulted. To the mixture was added MeOH (~1 mL) and the solution was concentrated in vacuo. The resulting material was purified by column chromatography [25 g ultra snap column, 0-100% (76:24 EtOAc:EtOH)/(heptane)] to give 75 mg of 75% pure product. The material was repurified via RP-HPLC (5-95% ACN/H2O, 0.1% NH4OH throughout) to provide the product as a white solid. [34 mg, 22%]

[Patent Reference: WO2015051043, page 91, (9.7 MB)]

Example 2

To a 250 mL RBF was added the SM (640 mg, 2.58 mmol) followed by DCM (8.6 mL). The resulting clear solution was cooled to -78 C and treated dropwise with DAST (1.022 mL, 7.73 mmol). After 3 min, the reaction flask was put in an ice/H2O bath and stirred for 4 h. Sat aq NaHCO3 was carefully added to quench the reaction. The mixture was extracted with EtOAc (2 x 20 mL). The combined organics were dried (MgSO4) and concentrated. The residue was adsorbed onto a silica gel plug and purified by silica gel chromatography (12 g Redi-Sep pre-packed silica gel column, 0-40% EtOAc/hexane) to provide the product as a colorless oil. [642 mg, 92%]

[Patent Reference: WO2014201173, page 377, (19.7 MB)]