Potassium Carbonate → tert-butyl (2R,5R)-2-ethynyl-5-(tert-butyldimethylsilyloxy-methyl)morpholine-4-carboxylate

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Reaction Steps

Dimethyl (1-diazo-2-oxpropyl)phosphonate (3.90 mL, 26.0 mmol) was added to tert-butyl (2S,5S)-5-({[tert-butyl(dimethyl)silyl]oxy}methyl)-2-formylmorpholine-4-carboxylate (Example 1, step 6) (7.78 g, 21.6 mmol) and K2CO3 (5.98 g, 43.3 mmol) in anhydrous MeOH (216 mL) at ambient temperature. The reaction was stirred for 2 hours then filtered and concentrated in vacuo. Saturated aqueous KH2PO4 was added and the mixture was extracted with ethyl acetate (×3). The combined organic fractions were dried (MgSO4), filtered and the solvent was evaporated under reduced pressure. Purification on silica gel (750 g) eluting with a gradient of 0-30% EtOAc/hexanes afforded the title compound (4.60 g, 12.9 mmol, 60% yield) as a colorless oil, MS (ESI): m/z=256.01 (M+H-Boc).

Provenance & Evidence