Tert-butyl 3-oxopiperidine-1-carboxylate → 3-Methylene-piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

Triphenylmethyl phosphonium iodide (22.14 g) and toluene (135 ml) are added into a three mouth flask (500 ml), stirred at room temperature to obtain a milky white suspension and quickly changed to orange after potassium tert-butanolate (5.31 g) is added. Then N-Boc-3-piperidone (6.0 g) in toluene (66 ml) is added into a constant pressure funnel and dropped into the flask under argon with obvious exothermic phenomenon, and kept at the temperature of 30° C. and the reaction is tracked by TLC after addition. After reaction, the mixture is filtered and washed with a saturated brine (200 ml, 2 times) and then adjusted to pH≈3 with diluted HCl (1M), and then washed with a saturated brine to pH=7, dried with anhydrous sodium sulfate, and filtered to obtain a yellow transparent liquid. The yellow transparent liquid is purified together with silica gel by chromatography (elution liquid: petroleum ether:ethyl acetate=15:1) to obtain a yellow oil-liquid of N-Boc-3-methylene piperidine (4.2 g).

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