Reaction Steps
4-O-Benzyl-N-benzyloxycarbonyl-1,5-imino-1,2,5-trideoxy-D-arabino-hexitol (25) (325 mg, 0.877 mmol) was dissolved in acetic acid (8 ml) and stirred under hydrogen at atmospheric pressure with palladium black (100 mg). After 18 hours, the solution was filtered and evaporated. Subsequent purification by flash chromatography (CMAW) and ion exchange gave 1,5-imino-1,2,5-trideoxy-D-arabino-hexitol as the hydrochloride salt (158 mg, 98%) a white crystalline solid, m.p. (methanol-ether) 173°-175° C., [α]20D +17.9° (c, 0.78 in water); νmax (KBr disc) 3370, 1615, 1390, 1055, 935 and 660 cm-1 ; 1H NMR (D2O) δ 1.58 (1H, dddd, H-2, J2,2' 14.2 Hz, J2,3 11.4 Hz, J2,1 13.6 Hz, J2,1' 4.6 Hz); 2.06 (1H, dddd, J2',1' 2.4 Hz, J2',3 4.8 Hz, J2',1 3.2 Hz); 2.90-3.01 (2H, m, H-5, H-1); 3.30 (1H, ddd, H-1', J1,1' 13.2 Hz); 3.38 (1H, dd, H-4, J3,4 9.2 Hz, J4,5 10.5 Hz); 3.57 (1H, ddd, H-3); 3.73, 3.79 (2H, 2×dd, H-6,6', J6,6' 12.7 Hz, J5,6 5.2 Hz, J5,6' 3.4 Hz). 13C NMR δ29.33 (t, C-2); 42.66 (t, C-1); 58.53 (t, C-6); 60.68 (d, C-5); 70.39, 71.24 (2×d, C-3, C-4). m/z: 148 (M+H+, 100%), 116 (10%), 72 (8%). Also characterized as free base, m.p. (acetone-water) 178°-180° C., [lit.20 180°-184° C.], [α]20D +21.0° (c 0.3 in water) [lit.20 +24.7 (c 0.4 in water)]; 1H NMR δ 1.28 (1H, dddd, H-2), 1.81 (1H, dddd, H-2'), 2.40 (1H, ddd, H-1), 2.83 (1 H, ddd, H-1'), 2.99 (1H, dd, H-4), 3.37 (1H, m, H-3), 3.46 (1H, dd, H-6), 3.68 (1H, dd, H-6'); 13C NMR δ 33.45 (t, C-2), 43.30 (t, C-1), 61.59 (d, C-5), 62.45 (t, C-6), 73.98 (2×d, C-3,4).
