Diethyl Pyrocarbonate → HCID 54479013, compound

Participants

Reaction Steps

To a DMF solution (40 ml) containing 9b (6.24 g, 26.2 mmole) and (S) (-)-ethyl prolinate (4.20 g, 29.3 mmole), a DMF solution (40 ml) of DEPC (4.70 g, 28.8 mmole) is added, and then a DMF solution (40 ml) of triethylamine (2.65 g, 26.2 mmole) is dropwise added thereto at 0° C. in 5 minutes. The resultant mixture is stirred at 0° C. for 2 hours and then at room temperature for 48 hours in a nitrogen stream. After completion of the reaction, the reaction mixture is diluted with ethyl acetate (1.2 liters), and the ethyl acetate solution is washed with 5% hydrochloric acid (120 ml×2), water (120 ml×2), a saturated aqueous solution of sodium chloride (120 ml×2), a saturated aqueous solution of sodium hydrogen carbonate (120 ml×2), water (120 ml×2) and a saturated aqueous solution of sodium chloride (120 ml×2) in order, dried over anhydrous magnesium sulfate and subjected to filtration and evaporation to afford the crude product 10b as a pale brown caramel (10.3 g, 104%), which is purified by column chromatography (silica gel, 250 g; solvent, ether) to obtain a pure product 10b as a colorless caramel (8.3 g, 83%). [α]D20 -10.3° (c=2.28, ethanol). IRνmaxfilm cm-1 : 1730 (CO2Et), 1635 (C=C), 1603 (CON). NMR (in CDCl3 ): 1.27 (3H, t, J=7.5Hz, CO2CH2CH3), 1.70-3.10 (8H, m, CH2CH2C= and NCH2CH2CH2), 3.50-3.92 (2H, m, N--CH2), 3.78 (6H, s, two OCH3), 4.17 (2H, q, J=7.5Hz, CO2CH2CH3), 4.50 (1H, m, NCHCO), 6.15 (1H, d, J=10.7Hz, one of aromatic protons), 6.29 (1H, d, J=10.7Hz, one of aromatic protons), 7.21 (1H, broad s, CH=).

Provenance & Evidence