Oxalic Acid → HCID 69541953, compound

Participants

Reaction Steps

Dicyclohexylcarbodiimide (DCC, 3.53 g, 17.1 mmol) and dichloroacetic acid (0.235 mL, 2.56 mmol) were added to a solution of 14 (2.00 g, 5.71 mmol) in anhydrous benzene (50 mL), DMSO (35 mL) and pyridine (0.46 mL). The resulting solution was stirred at room temperature under argon during 4 h and diluted with ethyl acetate (300 mL). Oxalic acid (1.54 g, 17.1 mmol) dissolved in methanol (4.6 mL) was added and the reaction mixture was stirred at room temperature during 1 h and then filtered to eliminate precipitated dicyclohexylurea (DCU). The filtrate was washed with brine (3×300 mL), with a saturated aqueous sodium hydrogen carbonate solution (2□ 300 mL) and fmally with water (3×200 mL) before being dried over sodium sulphate and evaporated under reduced pressure. The resulting residue was co-evaporated several times with absolute ethanol and dissolved in a mixture of absolute ethanol (31 mL) and anhydrous benzene (15 mL). The resulting solution as then cooled to 0° C. and sodium borohydride (NaBH4, 0.32 g, 8.56 mmol) was added. The reaction mixture was stirred at room temperature under argon during 1 h and diluted with ethyl acetate (300 mL) filtered. The filtrate was washed with a saturated aqueous sodium chloride solution (3×300 mL) and with water (2□ 200 mL) before being dried over sodium sulphate and evaporated under reduced pressure. The resulting residue was purified by silica gel column chromatography [eluent: stepwise gradient of methanol (0-6%) in chloroform] to. give pure 15 (1.10 g, 55%), as a white foam: mp 171-172□C; UV (ethanol): λmax228 nm (ε14700) 270 nm (ε9100), λmin248 nm (ε5000); 1H NMR (DMSO-d6): δ11.8 (br s, 1H, NH), 8.0-7.5 (m, 6H, C6H5CO and H-6), 5.90 (dd, 1H, H-1′, J1′-2′=4.1 Hz and J1′-F5=1.8 Hz), 5,5 (br s, 1H, OH-2′), 4.7 (br q, 1H, H-4′J=11.7 Hz and J=7.0 Hz), 4.4-4.3 (m, 3H, H-2′, H-5′ and H-5″), 2.4 (m, 1H, H-3′), 1.9-1.8 (m, 1H, H-3″); MS (maxtrix GT): FAB>0 m/z 701 (2M+H)+, 351 (M+H)+, 221 (S)+, 131 (BH2)+, 105 (C6H5CO)+; FAB<0 m/z 1049 (3M-H)−, 699 (2M−H)−, 349 (M−H)−; 129 (B)−, 121 (C6H5CO2)−; [α]D20=−101 (c, 0.70 DMSO).

Provenance & Evidence