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598
KHAN ET AL.
1H, –OCHAPh), 4.65 (d, J =3.7Hz, 1H, H-2, major isomer), 4.60(d, J =3.7 Hz,
1H, H-2, minor isomer), 4.45(d, J = 12 Hz, 1H, –OCHBPh), 4.16–4.08 (m, 3H,
H-4 and –OCH2CH3), 3.90 (d, J =3.1 Hz, 1H, H-3), 3.40 (m, 1H, H-5), 2.65 (m,
2H, –NHCH2), 2.38 and 2.32 (dd, J = 15.6 Hz and 4.7 Hz, 1H, H-6A), 2.25 and 2.19 (dd,
J =15.6 Hz and 6.6 Hz, 1H, H-6B), 1.72[bs, 1H, –NH(CH2)3CH3], 1.50[s,3H, C(CH3)2],
1.42 (m, 2H, –NHCH2.CH2), 1.32[s, 3H, C(CH3)2], 1.30 (m, 2H, –NH.CH2.CH2.CH2 ),
1.28 (t, J = 7.1 Hz, 3H, –OCH2CH3), 0.88 (t, J = 7.2 Hz, 3H, –NH(CH2)3CH3). 13C NMR
(proton decoupled, CDCl3); d 172.20 (C O), 137.51, 129.10, 128.42 and 128.14
(each Ar–C), 111.90[C(CH3)2], 105.21(C-1), 82.63 (C-2), 82.26 (C-4), 82.12 (C-3),
71.88 (–OCH2Ph), 60.68 (–OCH2CH3), 54.44 (C-5), 47.34 (–NHCH2), 36.74 (C-6),
32.90 (–NHCH2CH2), 27.14 and 26.73[2 ꢀ C(CH3)2], 20.81[–NH(CH2)2CH2CH3],
14.57 (–OCH2CH3), 14.36[–NH(CH2)3CH3].
Anal. Calcd for C23H35O6N (421): C, 65.56; H, 8.31; N, 3.32. Found: C, 65.12;
H, 8.81; N, 3.22.
Ethyl[3-O-benzyl-5-benzylamino-5, 6-dideoxy-1, 2-O-isopropylidene]- -L-ido-
heptofuranuronates (3c, major). Colourless solid mp 74°C, Rf 0.41 (EtOAc/hexane,
1:5), yield 96%. [a]20D ꢁ 38.94 (c, 0.012, ethyl acetate); MS (FAB): m/z 456 (M +H) + ;
IR (KBr); nmax cm ꢁ 1 3350(–NH), 3020, 2980, 2920(CH3 and CH2 stretching): 1710
1
(C O). H NMR (200 MHz, CDCl3); d 7.25 (m, 10H, Ar-H), 5.94 (d, J = 3.89 Hz, 1H,
H-1), 4.69(d, J = 11.82 Hz, 1H, –OCHAPh), 4.64(d, J =3.93Hz, 1H, H-2), 4.44 (d,
J =11.8Hz, 1H, –OCHBPh), 4.25 and 4.19(dd, J =8.8 Hz and 3.2 Hz, 1H, H-4), 4.10(q,
J =7.14 Hz, 2H, –OCH2CH3), 3.94 (d, J =3.19 Hz, 1H, H-3), 3.84 (s, 2H, –NHCH2Ph),
3.52(m, 1H, H-5), 2.46 and 2.40 (dd, J = 15.6 Hz and 4.7 Hz, 1H, H-6A), 2.34 and 2.28
(dd, J =15.6 Hz and 6.6 Hz, 1H, H-6B), 1.81 (bs, 1H, –NHCH2Ph), 1.47 and, 1.31[each s,
each 3H, C (CH3)2], 1.24 (t, J =7.14Hz, 3H, –OCH2CH3). 13C NMR (proton decoupled,
CDCl3); d 172.80 (C O), 141.07, 137.97, 128.86,128.69, 128.42, 128.26, 128.12 and
127.27 (each Ar–C), 111.98[C(CH3)2], 105.20 (C-1), 82.60 (C-2), 82.40 (C-4), 82.22
(C-3), 72.49 (–OCH2Ph), 60.66 (–OCH2CH3), 53.07 (C-5), 51.67 (–NHCH2Ph), 36.26
(C-6), 27.22 and 26.78[2 ꢀ C (CH3)2], 14.57 (–OCH2CH3).
Anal. Calcd for C26H33O6N (455): C, 68.57; H, 7.25; N, 3.07. Found: C, 68.92;
H, 7.01; N, 3.41.
Ethyl[3-O-benzyl-5-benzylamino-5,6-dideoxy-1,2-O-isopropylidene]- -D-gluco-
heptofuranuronate (4c, minor). Rf 0.47 (EtOAc/ hexane, 1:5), [a]20D ꢁ 42.76 (c, 0.012,
ethyl acetate); MS (FAB): m/z 456 (M + H) + ; IR(KBr); nmax cm ꢁ 1 3350(–NH), 3020,
2980, 2920 (CH3 and CH2 stretching): 1710 (C O). 1H NMR (200 MHz, CDCl3); d 7.26
(m, 10H, Ar-H), 5.89 (d, J =3.77 Hz, 1H, H-1), 4.67 (d, J = 11.72 Hz, 1H, –OCHAPh),
4.59(d, J =3.7 Hz, 1H, H-2), 4.53 (d, J = 11.69 Hz, 1H, –OCHBPh), 4.23 and 4.17 (dd,
J =7.0 Hz and 2.7 Hz, 1H, H-4), 4.12(q, J =7.2 Hz, 2H, –OCH2CH3), 4.08 (d, J =2.7 Hz,
1H, H-3), 3.85 (d, J = 12.8 Hz, 1H, –NHCHAPh), 3.72 (d, J =12.8 Hz, 1H, –NHCHBPh),
3.52(m, 1H, H-5), 2.85 and 2.78 (dd, J =15.6 Hz and 4.4 Hz, 1H, H-6A), 2.62 and 2.54 (dd,
J =15.6 Hz and 6.7 Hz, 1H, H-6B), 1.68 (s, 1H, –NHCH2Ph), 1.47 and 1.31[each s, each
3H, C (CH3)2], 1.24 (t, J =7.14Hz, 3H, –OCH2CH3). 13C NMR (proton decoupled,
CDCl3); d 172.15 (C O), 141.07, 137.52, 128.92,128.73, 128.66, 128.47, 128.32 and
127.19 (each Ar–C), 112.01[C(CH3)2], 105.29 (C-1), 82.76 (C-2), 82.26 (C-4), 82.19