Diethylamine → (S)-2-ethyl-2-hydroxy-3-methyl-but-3-enoic acid diethylamide

Beteiligte Stoffe

Reaktionsschritte

To a solution of 1.000 g of compound (20) as obtained from example 14 (6.95 mmol) in 30 mL dichloromethane were added dropwise at −15° C. 2.5 mL N-ethyldiisopropyl amine (14.60 mmol, 2.1 eq) and after additional 8 min. 1.53 mL thionyl chloride (20.85 mmol, 3.0 eq). After 50 min., a solution of 7.22 mL diethylamine (69.5 mmol, 10.0 eq) in 20 mL dichloromethane was added dropwise using a syringe pump (addition time: 60 min.). The reaction mixture was allowed to slowly warm up to room temperature overnight. The reaction mixture was diluted with 50 mL dichloromethane and was then washed with 50 mL aqueous hydrochloric acid (1.0 M). The organic phase was dried over 5 g sodium sulfate and was filtered. The solid was washed with 10 mL dichloromethane. After evaporation of solvent in a rotary evaporator (40° C./10 mbar), the crude product (1.36 g, 98% by weight) was obtained as a yellow oil, which was purified by column chromatography with heptane/ethyl acetate (9:1) yielding the title compound (0.900 g, 4.515 mmol, 65% by weight, er=93.4:6.6) as yellow oil.

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