Sodium Bicarbonate → 5-Azido-N-Boc-L-Norvaline

Participants

Reaction Steps

Sodium bicarbonate (1.99 g, 23.68 mmol) was added to a mixture of Boc-Orn-OH (Compound tk56) (1.0 g, 4.31 mmol) and copper sulfate pentahydrate (21 mg, 0.086 mmol) in methanol (20 mL)-water (6 mL) at room temperature, followed by addition of 1H-imidazole-1-sulfonyl azide hydrochloride synthesized by the method described in the literature (Org. Lett., 2007, 9, 3797) (1.08 g, 5.17 mmol). The reaction mixture was stirred at room temperature for 24 hours. The reaction mixture was cooled in an ice bath, followed by addition of a saturated aqueous potassium bisulfate solution (8 mL). The resulting mixture was extracted with ethyl acetate (three times), and the organic phase was concentrated under reduced pressure. The resulting residue was purified by reverse-phase silica gel column chromatography (0.05% aqueous trifluoroacetic acid solution/0.05% trifluoroacetic acid-acetonitrile solution) to afford (S)-5-azido-2-((tert-butoxycarbonyl)amino)pentanoic acid (Compound tk69) (1.19 g, quant.).

Provenance & Evidence