Potassium (Methoxymethyl)trifluoroborate

A vial is charged with PdCl₂ (COD) (3.6 mg, 12 µmol), dippf (10.5 mg, 25.0 µmol), 1 (55.5 mg, 0.25 mmol), 2 (68.4 mg, 0.33 mmol) and K₃PO₄ (382 mg, 1.80 mmol). The vial is purged with argon and a mixture of t-BuOH/H₂O (1.25 mL/1.25 mL) is added. The reaction mixture is heated to 110 °C for 4 h before cooling to rt. The reaction mixture is extracted with EtOAc (3 x 2 mL) and then dried (MgSO₄). The solvent is removed in vacuo, and the crude product is purified by silica gel chromatography (elution with hexanes/ EtOAc 92:8) to yield 3 in 71% yield (30.5 mg) as a yellow oil.

A procedure for alkylation of lepidine: Potassium (Methoxymethyl)trifluoroborate (152 mg, 1.0 mmol) and lepidine (143 mg, 1.0 mmol) are dissolved in a 1 : 1 mixture of acetic acid : water (13 mL), and trifluoroacetic acid (0.077 mL, 1.0 mmol) is added. The resulting mixture is stirred at room temperature until complete dissolution then manganese(III) acetate (670 mg, 2.5 mmol) is added in one portion. The mixture is stirred at 50 °C for 18 h. After cooling to room temperature, the mixture is slowly added to a saturated aq solution of Na₂CO₃ (50 mL). The aqueous layer then is extracted with EtOAc (3 x 20mL). The organic layers are washed with water (2 x 20 mL) then dried (MgSO₄), filtered, and evaporated under vacuum. The residue is purified by preparative plate chromatography (silica gel, hexanes / EtOAc 30 / 70) to give the desired compound (93.0 mg, 50% yield) as a colorless oil.