Benzyl chloroformate → Benzyl 3-hydroxy-4-(hydroxymethyl)piperidine-1-carboxylate

Participants

Reaction Steps

A solution of the 1-Benzyl-4-hydroxymethyl-piperidin-3-ol from Step 1 above (13.5 g) in methanol (450 mL) was hydrogenated at 50 psi over 20% palladium hydroxide on charcoal (10 g) for 48 h in three batches. The combined reaction mixtures were filtered and the filtrate evaporated to give an oil. This oil was dissolved in water (100 mL) and dioxane (100 mL), cooled to 5° C., and benzyl chloroformate (7.8 mL) was added slowly. 1M NaOH was added to maintain pH of 10–11. After 30 min, the cooling bath was removed and reaction mixture stirred for 30 min. The reaction mixture was concentrated to remove dioxane and the residue extracted with EtOAc (×3). The combined extracts were washed with brine, dried over anhydrous sodium sulfate and solvent evaporated to give a mixture of cis and trans products. Purified by flash column chromatography (80% EtOAc hexane to 5% MeOH EtOAc) gave the upper Rf cis isomer and the lower Rf trans isomer.

Provenance & Evidence