[Synthesis]
Mercury(II) acetate (20.7 g, 65.0 mmol) was added as 2-[benzyl-(2-methyl-allyl)-amino]-ethanol (13.0 g, 63.2 mmol), which was dissolved in a mixed solvent of water (45 mL) and THF (45 mL). After 3 hours of reaction, the reaction mixture was treated with 2.5 M NaOH aqueous solution (25 mL, 125 mmol) followed by the addition of NaBH4 (2.72 g, 71.9 mmol). After 19 h of reaction, the mixture was decanted from the metallic mercury and transferred to a partition funnel containing tert-butyl methyl ether (250 mL). The organic phase was separated, washed with water (250 mL), filtered through a silica gel plug and the filtrate concentrated. The residue was purified by fast chromatography using a gradient elution of 5% to 10% tert-butyl methyl ether in CH2Cl2. The grades containing 4-benzyl-2,2-dimethylmorpholine were collected, concentrated, dissolved in hexane (100 mL) and filtered through Celite. The filtrate was concentrated to give 4-benzyl-2,2-dimethylmorpholine (7.01 g, 54% yield) as a colorless liquid.1H NMR (DMSO-d6, 400 MHz) δ 7.20-7.40 (5H, m), 3.60 (2H, m), 3.42 (2H, s), 2.29 (2H, m), 2.10 (2H, s), 1.14 ( 6H, s). |