Water → 4-methylene-1-(tert-butoxycarbonyl)piperidine-2(S)-carboxylic acid benzyl ester

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Reaction Steps

To a suspension of methyl(triphenyl)phosphonium bromide (248 g, 0.69 mol) in anhydrous toluene (1 L) was added sodium hexamethyldisilazide (258 ml, 0.69 mmol) at 0° C., after addition was completed, the reaction mixture was warmed to room temperature, and stirred at room temperature for 1 hour, then cooled to 0° C. and the solution of (S)-4-oxo-piperidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester (intermediate 14, 210 g, 0.63 mol) in anhydrous toluene (0.5 L) was added. The resulting mixture was warmed to room temperature, and stirred at room temperature for 1 hour, added water (500 ml), extracted with ethyl acetate. The combined organic extracts were dried (Na2SO4), filtered and evaporated to obtain a crude that was purified by silica gel chromatography (petroleum ether/ethyl acetate from 10/1 to 5/1). (S)-4-Methylene-piperidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester was obtained as colourless oil (120 g), yield:57.4%.

Provenance & Evidence