Potassium Hydroxide → (-)-N-(3,4-Dihydro-2-naphthoyl)proline

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Reaction Steps

To a 50% aqueous ethanol solution (100 ml) containing potassium hydroxide (2.56 g, 0.039 mmole), (10a) (9.09 g, 0.030 mole) is added, and the mixture is stirred at room temperature for 5 hours. After completion of the reaction, the reaction mixture is concentrated to the one-fourth of the amount under reduced pressure, and the resultant aqueous alkaline solution is washed with ether (50 ml×2). The aqueous alkaline layer is adjusted to about pH 2 with conc. hydrochloric acid, and the precipitated product is extracted with ethyl acetate (150 ml×2). The ethyl acetate layers are combined, washed with a saturated aqueous solution of sodium chloride (30 ml×2) and dried over anhydrous magnesium sulfate. After filtration and evaporation, a pure product (11a) is obtained as a colorless caramel (8.1 g, 98%). [α]D20 -93.3° (c=2.16, chloroform). IRνmaxNujol cm-1 : 1730 (COOH), 1630 (C=C), 1570 (CON). NMR (in CDCl3): 1.73-2.43 (4H, m, NCH2CH2CH2), 2.43-3.15 (4H, m, CH2CH2C=), 3.69 (2H, t, J=6Hz, NCH2), 4.60 (1H, t, J=7Hz, NCHCO2), 6.75 (1H, s, CH=C), 7.09 (4H, s, aromatic proton), 8.65 (COOH).

Provenance & Evidence