Sodium borohydride → Benzyl 2-(1-hydroxyethyl)morpholine-4-carboxylate

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Reaction Steps

To a solution of 1.38 of 2-acetyl-4-benzyloxycarbonylmorpholine in 50 mL of 1:1 THF-EtOH was added 400 mg of sodium borohydride, in several portions. The mixture was stirred at room temperature for 2 h, then quenched by addition of 25 mL of saturated NaHCO3. The mixture was diluted with 75 mL of water and 25 mL of EtOAc. The phases were separated and the aqueous phase was extracted with 2×25 mL of EtOAc. The combined organics were washed with 25 mL of brine, dried over Na2SO4, and concentrated. The residue was purified by flash chromatography, eluting with 2:1 hexanes-EtOAc, to yield 383 mg of diastereomer 1, 341 mg of diastereomer 2, and 436 mg of a mixture of the two isomers. Data for diastereomer 1. Rf 0.35 (1:1 hexanes-EtOAc) 1H NMR (500 MHz, CDCl3): δ7.30-7.43 (m, 4H), 5.12-5.23 (m, 2H), 3.80-4.18 (m, 4H), 3.57 (br t, J=11.0Hz, 1H), 3.32 (br s, 1H), 2.84-3.11 (m, 2H), 2.05 (br s, 1H),1.22 (d, J=6.5 Hz, 3H). Data for diastereomer 2. Rf 0.28 (1:1 hexanes-EtOAc).

Provenance & Evidence