“…Calcd for C 12 H 19 NO 6 : C, 52.74; H, 7.01; N, 5.13. Found: C, 52.96; H, 7.32; N, 5.01.5(R,S)-Carboxy-3-[(1 0 R,2 0 R,3 0 S,4 0 R)-1 0 ,2 0 -O-isopropylidene-3 0 -O-methyltetrahydrofuranos-4 0 -yl]-2-isoxazoline(15).Colorless oil, Rf 0.40 (hexane:ethyl acetate, 1:1); [a] D 25 -418 (c 0.4, CHCl 3 ), MS (FAB) ¼ m/z 302 (M þ H) þ ; IR (Neat): n max cm 21 3352, 2937, 2362, 1769, 1709, 1658, 1622, 1447, 1378; 1 H NMR (CDCl 3 , 200 MHz): d 9.76 (bs, exchangeable with D 2 O, 1H, -COOH), 7.22 (m, 1H, H-4), 5.99, 5.91 (d, J ¼ 3.6 Hz, 1H, diastereomeric H-1 0 ), 4.84 (d, J ¼ 3.3 Hz, 1H, H-4 0 ), 4.59 (d, J ¼ 3.6 Hz, 1H, H-2 0 ), 4.13 (d, J ¼ 3.3 Hz, 1H, H-3 0 ), 3.43 (s, 3H, -OCH 3 ), 1.95 (d, J ¼ 6.9 Hz, 3H, CH 3 ), 1.81 (m, 1H, H-5) 1.49 and 1.33 [s, H, C(CH 3 ) 2 ]. 13 C NMR (CDCl 3 ): d 164.4 (C ¼ O), 163.8 (C5 5N); 149.R,S)-Carbethoxy-3-[(1 0 R,2 0 R,3 0 S,4 0 R)-3 0 -O-benzyl-1 0 ,2 0 -O-isopropylidenetetrahydrofuranos-4 0 -yl]-2-isoxazoline (16).…”