56% |
With sodium tetrahydroborate; In 1,4-dioxane; at 0 - 20℃; |
A solution of 0.8 g (4.65 mmol) of 7 in dioxane (8 mL) was treated with 0.2 g (50 mmol) of sodium borohydride in small portions with cooling in ice-water. the mixture then stirred at room temperature overnight, until TLC monitoring indicated completion and poured over crushed ice. Acidify the mixture by HCl 37% to consume the excess NaBH4. The product was extracted with 3 ×40 mL ether and The organic layers were combined, washed with water (1 × 30 mL), brine (1 × 30mL), and dried over Na2SO4. The solvent removed under reduced pressure and then purified by column chromatography (1:1 hexanes: ethyl acetate) to give pure 1 as a white solid (460 g, 2.64 mmol, 56 %). m.p. 51C. IR spectrum (cm-1): 3334, 2931, 2852, 1692 cm-1. 1H NMR (300 MHz,CDCl3) delta 6.07 (m, 2H, CH2OH and COOH), 3.63 (t, 2H, J = 6.6 Hz, CH2OH), 2.33 (t, 2H, J = 7.5Hz, CH2COOH), 1.62 (m, 4H, CH2CH2CH2OH and CH2CH2COOH), 1.25-1.32 (m, 8H, CH2). 13CNMR (75 MHz, CDCl3): delta 179.2 (s, COOH), 63.5 (t, CH2OH), 34.3, 32.9, 29.5, 29.3, 26.0, 25.0. |