3200
J. M. Vega-Pe´rez et al. / Tetrahedron: Asymmetry 12 (2001) 3189–3203
4.5.5. Benzyl 2-amino-(R)-4,6-O-benzylidene-2-deoxy-2-
N-[(2S,3R)-2,3-epoxy-3-phenylpropanoyl]-2-N-3-O-
68.9 (C-6), 63.6 (C-5), 58.6 (C-2), 54.4 [C
6
H(O)CHCH3],
53.8 [CH(O)C6 HCH3], 17,2 [CH(O)CHC6 H3]. HRMS
methylidene-b-
D
-allopyranoside 27. Two stereoisomers
(CI): [M+H]+, found 454.184981. C25H28NO7 requires
454.186578. Anal. calcd for C25H27NO7: C, 66.21; H,
6.00; N, 3.09. Found: C, 65.98; H, 5.99; N, 3.18%.
were obtained in 97:3 ratio [94% de for the (2S,3R)-iso-
mer]. The major isomer 27a (major Rf) was isolated by
column chromatography using hexane–ethyl acetate
(25:10) as eluent, yield: 0.66 g (85%). Mp 171–172°C;
[h]D +62.5 (c 0.5, CHCl3); MS (CI): m/z 516 (25%)
4.5.7. Benzyl 2-amino-(R)-4,6-O-benzylidene-2-deoxy-2-
N-[(E)-2,3-epoxypentanoyl]-2-N-3-O-methylidene-b-D-
allopyranoside 29. Two stereoisomers were obtained in
73:27 ratio [46% de for the (2S,3R)-isomer]. Both iso-
mers were isolated by column chromatography using
hexane–ethyl acetate (17:10) as eluent, yield: 0.58 g
(83%).
1
[M+H]+. H NMR (200 MHz, CDCl3): l 7.51–6.9 (m,
15H, 3Ph), 5.58 (s, 1H, PhCH
Hz, OCH2N), 4.6–4.3 (m, 6H, H-1, H-2, H-3, H-6e,
OCH2Ph), 4.23 [d, 1H, Jtrans 1.7 Hz, CH(O)CHPh], 3.95
[d, 1H, Jtrans 1.7 Hz, CH(O)CHPh], 3.9–3.7 (m, 3H,
H-4, H-5, H-6a). 13C NMR (50 MHz, CDCl3): l 165.2
(CꢁO), 136.6–126.0 (3Ph), 102.8 (PhCH), 99.7 (C-1),
80.9 (OCH2N), 76.8 (C-3), 76.3 (C-4), 71.4 (OCH2Ph),
68.9 (C-6), 63.7 (C-5), 58.7 (C-2), 58.2 [CH(O)CHPh],
56.6 [CH(O)CHPh]. Anal. calcd for C30H29NO7: C,
6 ), 5.19 (dd, 2H, Jgem 5.7
6
6
6
6
6
4.5.7.1. Major isomer 29a (major Rf). Mp 78–79°C;
[h]D −53.6 (c 0.5; CH2Cl2); MS (CI): m/z 468 (19%)
6
1
6
[M+H]+. H NMR (200 MHz, CDCl3): l 7.5–7.2 (m,
69.89; H, 5.67; N, 2.72. Found: C, 69.83; H, 5.79; N,
2.70%.
10H, 2Ph), 5.59 (s, 1H, PhC
Hz, OCH2N), 4.93 (d, 1H, Jgem 11.4 Hz, OCHA
4.64 (d, 1H, J1,2 7.5 Hz, H-1), 4.54 (d, 1H, Jgem 11.4 Hz,
OCHAHBPh), 4.5–4.4 (m, 2H, H-3, H-6e), 4.29 (dd, 1H,
6
H), 5.17 (dd, 2H, Jgem 5.2
6
HBPh),
6
4.5.6. Benzyl 2-amino-(R)-4,6-O-benzylidene-2-deoxy-2-
N-[(E)-2,3-epoxybutanoyl]-2-N-3-O-methylidene-b-D-
allopyranoside 28. Two stereoisomers were obtained in
72:28 ratio [44% de for the (2S,3R)-isomer]. Both iso-
mers were isolated by column chromatography using
hexane–ethyl acetate (17:10) as eluent, yield: 0.54 g
(80%).
J1,2 7.5 Hz, J2,3 4.2 Hz, H-2), 4.0–3.9 (m, 2H, H-4, H-5),
3.78 (t, 1H, J5,6a=J6e,6a 10.0 Hz, H-6a), 3.49 [d, 1H,
Jtrans 2.0 Hz, CH
Hz, J 4.1 Hz, CH(O)CH
CH(O)CHCH2CH3], 0.76 [t, 3H,
CH(O)CHCH2CH3
166.4 (CꢁO), 136.6–126.3 (2Ph), 102.8 (PhC
6
(O)CHCH2CH3], 3.19 [dt, 1H, Jtrans 2.0
6
CH2CH3], 1.5–1.2 [m, 2H,
6
J
7.5 Hz,
H), 100.4
6
]. 13C NMR (50 MHz, CDCl3): l
6
(C-1), 80.9 (OCH2N), 76.8 (C-3), 76.4 (C-4), 71.8
(OCH2Ph), 69.0 (C-6), 63.9 (C-5), 59.5 (C-2), 58.7
[CH(O)CHCH2CH3], 52.5 [CH(O)CHCH2CH3], 23.7
[CH(O)CHCH2CH3], 9.2 [CH(O)CHCH2CH3]. Anal.
4.5.6.1. Major isomer 28a (major Rf). Mp 113–114°C;
[h]D −21.1 (c 0.6, CH2Cl2); MS (CI): m/z 454 (36%)
6
6
6
1
[M+H]+. H NMR (500 MHz, CDCl3): l 7.5–7.2 (m,
6
6
10H, 2Ph), 5.61 (s, 1H, PhCH
Hz, OCH2N), 4.96 (d, 1H, Jgem 11.4 Hz, OCHA
4.67 (d, 1H, J1,2 7.6 Hz, H-1), 4.56 (d, 1H, Jgem 11.4 Hz,
OCHAHBPh), 4.5–4.4 (m, 2H, H-3, H-6e), 4.28 (dd, 1H,
6
), 5.17 (dd, 2H, Jgem 5.5
calcd for C26H29NO7: C, 66.80; H, 6.25; N, 3.00.
Found: C, 66.56; H, 6.19; N, 3.04%.
6
HBPh),
6
4.5.7.2. Minor isomer 29b (minor Rf). Mp 80–81°C;
[h]D −144.2 (c 0.4; CH2Cl2); MS (CI): m/z 468 (33%)
J1,2 7.6 Hz, J2,3 4.2 Hz, H-2), 3.99 (m, 1H, J4,5=J5,6a 9.9
Hz, J5,6e 5.0 Hz, H-5), 3.91 (dd, 1H, J3,4 3.2 Hz, J4,5 9.9
Hz, H-4), 3.80 (t, 1H, J5,6a=J6e,6a 9.9 Hz, H-6a), 3.43 [d,
1
[M+H]+; H NMR (200 MHz, CDCl3): l 7.5–7.3 (m,
10H, 2Ph), 5.57 (s, 1H, PhCH
2H, OCH2N), 4.91 (d, 1H, Jgem 11.2 Hz, OCHA
4.66 (d, 1H, J1,2 7.5 Hz, H-1), 4.64 (d, 1H, Jgem 11.2 Hz,
OCHAHBPh), 4.5–4.4 (m, 2H, H-3, H-6e), 4.12 (dd, 1H,
J1,2 7.5 Hz, J2,3 4.3 Hz, H-2), 4.0–3.7 [m, 4H, H-4, H-5,
H-6a, CH(O)CHCH2CH3], 3.15 [m, 1H, CH(O)-
CHCH2CH3], 1.61 [m, 2H, CH(O)CHCH2CH3], 0.90 (t,
3H, J 7.5 Hz, CH(O)CHCH2CH3
]. 13C NMR (50 MHz,
CDCl3): 166.7 (CO), 136.6–126.2 (2Ph), 102.8
(PhCH), 100.1 (C-1), 80.8 (OCH2N), 77.0 (C-3), 76.3
(C-4), 71.9 (OCH2Ph), 69.0 (C-6), 63.6 (C-5), 59.3
(C-2), 58.6 [CH(O)CHCH2CH3], 52.4 [CH(O)CHCH2-
CH3], 24.3 [CH(O)CHCH2CH3], 9.4 [CH(O)CHCH2-
H3]. HRMS (CI): [M+H]+, found 468.201746.
6
), 5.14 (dd, Jgem 5.6 Hz,
1H, Jtrans 1.8 Hz, CH
1.8 Hz, J 5.1 Hz, CH(O)CH
CH(O)CHCH
3]. 13C NMR (125 MHz, CDCl3): l 166.1
(CꢁO), 136.6–126.2 (2Ph), 102.7 (PhCH), 100.5 (C-1),
80.8 (OCH2N), 76.8 (C-3), 76.3 (C-4), 71.8 (OCH2Ph),
68.9 (C-6), 63.8 (C-5), 58.7 (C-2), 54.5 [CH(O)CHCH3],
53.9 [CH(O)CHCH3], 16.3 [CH(O)CHCH3]. Anal. calcd
6
(O)CHCH3], 3.24 [dq, 1H, Jtrans
6
HBPh),
6
CH3], 0.96 (d, 3H, J 5.1 Hz,
6
6
6
6
6
6
6
6
6
6
6
for C25H27NO7: C, 66.21; H, 6.00; N, 3.09. Found: C,
66.07; H, 6.18; N, 2.97%.
l
6
6
4.5.6.2. Minor isomer 28b (minor Rf). Mp 83–84°C;
[h]D −102.7 (c 0.4, CH2Cl2); MS (CI): m/z 454 (53%)
6
6
6
1
[M+H]+; H NMR (200 MHz, CDCl3): l 7.5–7.3 (m,
C6
10H, 2Ph), 5.58 (s, 1H, PhCH
Hz, OCH2N), 4.92 (d, 1H, Jgem 11.3 Hz, OCHA
4.7–4.6 (m, 2H, H-1, OCHAHBPh), 4.4–4.2 (m, 2H,
6
), 5.14 (dd, 2H, Jgem 5.6
C26H30NO7 requires 468.202228. Anal. calcd for
C26H29NO7: C, 66.80; H, 6.25; N, 3.00. Found: C,
66.62; H, 6.39; N, 2.88%.
6
HBPh),
6
H-3, H-6e), 4.11 (dd, 1H, J1,2 7.5 Hz, J2,3 4.2 Hz, H-2),
4.0–3.8 (m, 3H, H-4, H-5, H-6a), 3.75 [d, 1H, Jtrans 2.1
Hz, CH
Hz, CH(O)CH
CH(O)CHCH
3]. 13C NMR (50 MHz, CDCl3): l 166.4
(CꢁO), 136.6–126.3 (2Ph), 102.8 (PhCH), 100.0 (C-1),
80.8 (OCH2N), 77.0 (C-3), 76.4 (C-4), 71.9 (OCH2Ph),
6
(O)CHCH3], 3.22 [dq, 1H, Jtrans 2.1 Hz, J 5.1
4.5.8. Benzyl 2-amino-(R)-4,6-O-benzylidene-2-deoxy-2-
N-(2,3-epoxy-3-methylbutanoyl)-2-N-3-O-methylidene-b-
6
CH3], 1.31 [d, 3H, 5.1 Hz,
J
6
D-allopyranoside 30. Two stereoisomers were obtained
6
in 74:26 ratio (48% de). Column chromatography using
hexane–ethyl acetate (15:10) as eluent allowed the
6