Hydrochloric Acid → trans-1-Tert-butoxycarbonyl-4-methyl-piperidine-3-carboxylic acid

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Reaction Conditions

Reaction Steps

To a flask containing (+/−)-4-methyl-piperidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-ethyl ester (1.12 g, 4.1 mmol; from example 8 above) was taken up in tetrahydrofuran (12 mL) and methanol (3 mL) and cooled to 0° C. (ice bath). A solution of lithium hydroxide (4.5 mL, 1M) was added and the mixture was warmed to ambient over 3 hours. Extra methanol (2 mL) was added and the material was heated to 60° C. (oil bath) for 5.5 hours. The mixture was cooled to ambient and treated with 1N hydrochloric acid solution (4.7 mL) with vigorous stirring. The solvent was stripped and the remainder was dried under high vacuum for several hours, providing 1.06 g of mainly trans-(+/−)-4-methyl-piperidine-1,3-dicarboxylic acid 1-tert-butyl ester: as a off-white solid. MS (M−H)−=242.

Provenance & Evidence