Potassium Carbonate → (3R,4R)-1-tert-butyl 3-ethyl 4-((R)-1-phenylethylamino)-piperidine-1,3-dicarboxylate

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Reaction Steps

In a dry flask (3S,4R)-4-[(R)-1-phenyl-ethylamino]-piperidine-1,3-dicarboxylic acid 1-tert-butyl ester 3-methyl ester (13.78 g, 38.0 mmol) was dissolved in ethanol (400 mL) along with 3 Å molecular sieves (1.04 g). The mixture was heated to reflux over 2.5 hours. Potassium carbonate (26.3 g) was added and refluxing continued for 4 additional hours. The reaction mixture was cooled, filtered through a bed of celite, and concentrated in vacuo to give a crude oil (16.05 g). Purification by flash column chromatography (20-50% ethyl acetate/hexanes) provided a colorless oil (3.24 g, 23%). Unepimerized ethyl ester was also isolated (7.55 g, 53%).

Provenance & Evidence