Ammonium Chloride → HCID 15119366, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 1,6:2,3-dianhydro-4-O-benzyl-β-D-mannopyranose (7, 5.0 g, 21.3 mmol) in dry THF (25 ml), was added a solution of 1.77M vinylmagnesiumbromide 16 in THF (120.5 ml, 213 mmol). The mixture was gently refluxed for 3 h at 60° C. After cooling to room temperature a 2M NH4Cl aq. solution (650 ml, pH 8) was slowly added. The aqueous layer was extracted with ethyl acetate (2×250 ml). The combined organic layers were dried (MgSO4), filtered and concentrated. The crude product (4.87 g, 87%) was purified by flash chromatography using ethyl acetate/pentane 1:2 as eluent, to give 1,6-anhydro-4-O-benzyl-2-deoxy-2-C-vinyl-β-D-glucopyranose (8) as a white crystalline compound in 75.5% (4.23 g) yield. After recrystallization in ethanol: mp. 88°-91° C.; [α]D20 =-2.3° (c 4.1, CHCl3) (lit17 mp. 91°-93° C. [α]D20 =+1.2° (c 1.3, CHCl3)). 13C-NMR (50 MHz, CDCl3):δ135.5 (CH=), 137.7, 128.3), 127.6, 127.5 (Ph), 117.2 (CH2 =), 103.5 (C-1), 78.8 (C-4), 74.6 (C-3), 71.3, 70.4 (C-5, OCH2Ph), 65.4 (C-6), 51.8 ppm (C-2). 1H NMR (200 MHz, CDCl3): δ7.35 (d, 5H, Ph), 5.99 (m, 1H, CH=CH2), 5.25 and 5.17 (s, 1H og d, 1H, CH2 =), 4.63) (dd, 3H, OCH2Ph and H-5), 4.09 and 3.75 (d, 1H and m, 2H, H-3, H-6 and H-6'), 3.43 (s, 1H, H-4), 2.80 (broad s, 1H, OH), 2.45 (d, 1H, H-2). Anal. Calc. for C15H18O4 : C, 68.69; H, 6.92. Found: C, 68.58; H, 6.94.

Provenance & Evidence