Boron trifluoride etherate → (2S,3S)-methyl 2-((tert-butoxycarbonyl)amino)-3-((R)-hex-5-en-2-yloxy)pentanoate

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Reaction Steps

To a round-bottom flask equipped with a stir bar was added (2S,3R)-1-tert-butyl 2-methyl 3-ethylaziridine-1,2-dicarboxylate (691, 3.02 mmol) and CH2Cl2 (12 mL). To the solution was added (R)-hex-5-en-2-ol (363 mg, 3.62 mmol), then BF3-OEt2 (1.0M in CH2Cl2, 0.30 mL). The solution was stirred at room temperature for 16 h. The solution was transfered to a separatory funnel and was diluted with CH2Cl2, then the solution was washed with aq. saturated NaHCO3; then brine. The organic phase was dried over Na2SO4; filtered; then concentrated in vacuo. The resulting residue was subjected to silica gel chromatography (hexanes:EtOAc 90:10 to 70:30) to afford (2S,3S)-methyl 2-((tert-butoxycarbonyl)amino)-3-((R)-hex-5-en-2-yloxy)pentanoate as a colorless oil (426 mg, 43%). 1H-NMR (500 MHz, CDCl3) δ 5.81 (ddt, J=17.0, 10.4, 6.5 Hz, 1H), 5.19 (d, J=7.7 Hz, 1H), 5.08-5.00 (m, 1H), 4.96 (dd, J=10.2, 1.7 Hz, 1H), 4.50 (dd, J=8.3, 3.5 Hz, 1H), 3.75 (s, 3H), 3.65-3.58 (m, 1H), 3.57-3.50 (m, 1H), 2.19-2.06 (m, 2H), 1.66-1.56 (m, 2H), 1.55-1.38 (m, 11H), 1.13 (d, J=6.1 Hz, 3H), 0.97 (t, J=7.3 Hz, 3H).

Provenance & Evidence