A. Berkin et al. / Carbohydrate Research 325 (2000) 30–45
43
J3,4 3.6 Hz, H-3), 5.83 (d, 1 H, J2,NH 9.4 Hz,
NH); 13C NMR (CDCl3): l 20.7 and 23.0
(OCOCH3, NCOCH3), 47.5 (C-2), 55.3
(OMe), 57.5 (C-4), 62.6 (C-5), 68.7 (C-3), 98.9
(C-1), 169.8 and 170.8 (OCOCH3, NCꢀO).
Anal. Calcd for C10H16ClNO5: C, 45.21; H,
6.07; Cl, 13.35; N, 5.27. Found: C, 45.14; H,
6.11; Cl, 13.31; N, 5.39.
product from CHCl3–i-Pr2O gave 26 (45 mg,
74.1%) as a white solid. 1H NMR spec-
troscopy indicated that the a and b anomers
were present in a ratio of 9.8:1, respectively.
Rf 0.17 (1:4 hexanes–EtOAc); mp 143–
144 °C; [h]D +0.34° (c 1.19, CHCl3); IR
(KBr): w 3260 (NH), 3090, 2990, and 2960
(CH), 1760 and 1740 (ester carbonyls), and
1
1660 cm−1 (amide). a Anomer: H NMR
Methyl 2-acetamido-2,4-dideoxy-i- -threo-
L
(CDCl3): l 1.79–1.91 (m, 1 H, H-4%), 1.95,
2.07, and 2.11 (3 s, 9 H, 2 OAc, NAc), 1.96–
2.08 (m, 1 H, H-4), 3.60 (overlapping dt, 1 H,
J4,5% 2.8 Hz, H-5%), 4.08 (dt, 1 H, J4,5 4.3, J5,5%
12.7 Hz, H-5), 4.10–4.16 (m, 1 H, H-2), 4.94
(dt, 1 H, J2,3 9.1, J3,4 4.7 Hz, H-3), 5.49 (d, 1
H, J2,NH 9.2 Hz, NH), 5.57 (d, 1 H, J1,2 7.1
Hz, H-1); 13C NMR (CDCl3): l 20.9, 21.0,
and 23.2 (2 OCOCH3, NCOCH3), 29.4 (C-4),
52.3 (C-2), 61.1 (C-5), 69.8 (C-3), 93.4 (C-1),
169.7, 170.0, and 170.8 (2 OCOCH3, NCꢀO).
pentopyranoside (28).—Following the same
procedure as for the preparation of 23, 27
(0.203 g, 0.764 mmol) was converted into 28
(97.0 mg, 67.1%): Rf 0.16 (5:1 EtOAc–
Me2CO); mp 142–142.5 °C; [h]D +99.2° (c
1.33, CHCl3); IR (KBr): w 3300 (OH and NH),
3080, 3000, 2920, 2890, 2850, and 2830 (CH),
1
and 1650 cm−1 (amide); H NMR (CDCl3): l
1.66–1.94 (m, 1 H, H-4%), 1.98–2.03 (m, 1 H,
H-4), 2.06 (br s, 4 H, NAc, OH), 3.37 (s, 3 H,
OMe), 3.55–3.71 (m, 2 H, H-3, H-5%), 3.78 (dt,
1 H, J4,5 4.8, J5,5% 10.7 Hz, H-5), 3.90 (ddd, 1
H, J2,3 9.9 Hz, H-2), 4.67 (d, 1 H, J1,2 3.6 Hz,
H-1), 5.97 (d, 1 H, J2,NH 8.3 Hz, NH); 13C
1
b Anomer: H NMR (CDCl3): l 1.86–1.93
(m, 1 H, H-4%), 1.93, 2.05, and 2.14 (3 s, 9 H,
2 OAc, NAc), 1.96–2.06 (m, 1 H, H-4), 3.80–
3.83 (m, 2 H, H-5, H-5%), 4.27 (ddd, 1 H, H-2),
5.13 (dt, 1 H, J2,3 10.7, J3,4 5.0 Hz, H-3), 5.63
(d, 1 H, J2,NH 9.2 Hz, NH), 6.11 (d, 1 H, J1,2
NMR (CDCl3, 50.323 MHz):
l
23.15
(NCOCH3), 33.9 (C-4), 54.9 (C-2), 55.6
(OMe), 58.1 (C-5), 68.0 (C-3), 98.9 (C-1),
171.9 (NCꢀO). Anal. Calcd for C8H15NO4: C,
50.79; H, 7.99; N, 7.40. Found: C, 50.53; H,
7.72; N, 7.27.
13
3.5 Hz, H-1); C NMR (CDCl3): l 20.9, 21.0,
and 23.1 (2 OCOCH3, NCOCH3), 30.4 (C-4),
51.8 (C-2), 59.8 (C-5), 68.1 (C-3), 92.2 (C-1),
169.2, 169.95, and 171.4 (2 OCOCH3, NCꢀO).
Anal. Calcd for C11H16NO6: C, 51.17; H, 6.25;
N, 5.42. Found: C, 51.13; H, 6.50; N, 5.54.
Methyl 2 - acetamido - 3 - O - acetyl - 2,4 - di-
deoxy - i -
L
- threo - pentopyranoside (29).—
Compound 27 (0.412 g, 1.55 mmol) was pro-
cessed following the same procedure as for the
preparation of 24 to afford a product as a
white residue that was purified by flash chro-
matography on silica gel (1:4 hexanes–
EtOAc) and then recrystallized from
hexanes–EtOAc to give 29 (0.198 g, 55.2%):
Rf 0.15 (1:4 hexanes–EtOAc); mp 146–
147 °C; [h]D +95.2° (c 1.74, CHCl3); IR
(KBr): w 3240 and 3210 (OH and NH), 3060,
2900, and 2850 (CH), 1730 (ester carbonyl),
Methyl
2,4-dideoxy-i-
2-acetamido-3-O-acetyl-4-chloro-
-arabinopyranoside (27).—
L
Compound 21 (0.893 g, 4.30 mmol) was
processed following the same procedure as for
the preparation of 22 to afford a product as a
white residue that was purified by flash chro-
matography on silica gel (1:3 hexanes–
EtOAc) and then recrystallized from
hexanes–EtOAc to give 27 (0.930 g, 81.4%):
Rf 0.79 (5:1 CHCl3–MeOH); mp 172–173 °C;
[h]D +21.0° (c 0.95, MeOH); IR (KBr): w
3410 (NH), 3260, 3080, 3010, 2950, and 2840
(CH), 1750 (ester carbonyl), and 1650 cm−1
1
and 1650 cm−1 (amide); H NMR (CDCl3): l
1.78–1.89 (m, 1 H, H-4%), 1.91–1.95 (m, 1 H,
H-4), 1.95 and 2.02 (2 s, 6 H, OAc, NAc), 3.36
(s, 3 H, OMe), 3.66 (ddd, 1 H, J4,5% 1.8, J4%,5%
5.3 Hz, H-5%), 3.74 (dt, 1 H, J4,5 2.6, J5,5% 11.6
Hz, H-5), 4.14 (dt, 1 H, H-2), 4.68 (d, 1 H, J1,2
3.5 Hz, H-1), 5.08 (dt, 1 H, J2,3 10.2, J3,4 5.1
1
(amide); H NMR (CDCl3): l 1.91 and 2.03 (2
s, 6 H, OAc, NAc), 3.34 (s, 3 H, OMe), 3.71
(dd, 1 H, J4,5eq 2.0 Hz, H-5eq), 4.02 (dd, 1 H,
J4,5ax 1.3, J5ax,5eq 12.8 Hz, H-5ax), 4.32–4.33
(m, 1 H, H-4), 4.60 (ddd, 1 H, H-2), 4.69 (d, 1
H, J1,2 3.5 Hz, H-1), 5.09 (dd, 1 H, J2,3 10.9,
13
Hz, H-3), 5.69 (d, 1 H, J2,NH 9.0 Hz, NH); C
NMR (CDCl3): l 21.1 and 23.35 (OCOCH3,