Diisopropylamine → 1-Methyl-3-(phenylselanyl)piperidin-2-one

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Reaction Steps

A solution of diisopropylamine (3.02 mL, 21.21 mmol) in tetrahydrofuran (44.2 mL) under argon was cooled to −78° C. and added butyllithium solution, 2.5M in hexanes (8.48 mL, 21.21 mmol). After 5 min, a solution of 1-methylpiperidin-2-one (2 g, 17.67 mmol) in tetrahydrofuran (2 mL) was added dropwise. After stirring for 10 min, a solution of phenylselenenyl chloride (4.06 g, 21.21 mmol) in 16 mL of tetrahydrofuran was added, and the reaction was stirred at −78° C. for 2 h. The reaction was quenched with aqueous saturated NH4Cl solution and diluted with CH2Cl2; the aqueous layer was back-extracted with CH2Cl2 (1×). The combined organic extracts were dried (MgSO4), filtered, and concentrated in vacuo to afford a crude crop of 1-methyl-3-(phenylselanyl)piperidin-2-one in dichloromethane. To the crude 1-methyl-3-(phenylselanyl)piperidin-2-one in dichloromethane (50 mL) at 0° C. under argon was added 3-chlorobenzoperoxoic acid (7.92 g, 35.3 mmol). The resulting mixture was allowed to gradually warm to room temperature overnight. The orange suspension was filtered, and the filtrate was concentrated in vacuo and partitioned between CH2Cl2 and aqueous saturated NaHCO3 solution; the aqueous layer was back-extracted with CH2Cl2 (5×). The combined organic extracts were dried (MgSO4), filtered, and concentrated in vacuo. Flash column chromatography (20% EtOAc/Hexanes to 100% EtOAc) afforded 1-methyl-5,6-dihydropyridin-2(1H)-one (1.33 g, 67.7% yield) as a brown oil. [M+1]=112.2.

Provenance & Evidence