Y. Tang, D.P. Reddy and B. Yu
Tetrahedron 78 (2021) 131800
1.38e1.31 (m, 2.82H), 1.31e1.24 (m, 2.78H); 13C NMR (126 MHz,
81.39 (d, J ¼ 22.4 Hz), 76.53, 75.48, 75.12, 74.46 (d, J ¼ 2.1 Hz), 73.16
(d, J ¼ 5.1 Hz), 62.90, 20.95; Elemental analysis calcd (%) for
CDCl3)
d 112.60, 109.26, 106.54, 101.61, 85.06, 81.02, 80.33, 79.55,
73.22, 73.06, 71.64, 70.21, 66.95, 66.41, 59.05, 26.95, 25.93, 25.25,
24.56; HRMS (ESI) calcd for C15H26NaO7 [MþNa]þ 341.1576, found
341.1571.
C29H31FO6: C 70.43, H 6.32; found: C 70.24, H 6.38.
Component
benzyl- - glucopyranosyl-(1 / 6)-1,2:3,4-O-diisopropylidene-
-galactopyranose 5 (81 mg,
C was identified to be 6-O-acetyl-2,3,4-tri-O-
a,b-D
Cyclohexyl 2,3,4-tri-O-benzyl-
reaction mixture of glycosyl donor 1e (0.185 mmol, 78 mg) and
acceptor 2b (29 L, 0.278 mmol, 1.5 eq) in 2.0 mL dry CH2Cl2 was
stirred for 18 h in the presence of Cs2CO3 (0.370 mmol, 121 mg, 2.0
eq), 3 Å molecular sieves (300 mg) and NfF (0.370 mmol, 68 L, 2.0
eq) under the standard conditions. Eluent: petroleum ether/ethyl
a
,b
-D-arabinofuranoside (3i). A
a
-
D
a
/
b
¼ 3.7/1, 58%) as a colorless syrup.
The spectral data of 5 was identical with the literature data [31].
Component D was identified to be the unreacted donor 1b
(26 mg, 28%).
m
m
Self-condensation of donor 1a mediated by NfF. A 25 mL glass
Schlenk flask fitted with a resealable Teflon valve was equipped
with a magnetic stir bar and charged with glycosyl donor 1a
(0.189 mmol,100 mg), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq), and 3 Å
molecular sieves (300 mg), then, under argon protection, dry
acetate ¼ 15/1. Yield of 3i: 79 mg, 85%,
a
/
b
¼ 1/2.5. 3i: colorless
25
syrup; [
a
]
¼ ꢃ59.3 (c 0.15, CH2Cl2); 1H NMR (500 MHz, CDCl3)
D
d
7.49e7.27 (m, 9.25H), 5.28 (s, 0.40H), 5.16 (d, J ¼ 4.3 Hz, 1.0H), 4.74
(d, J ¼ 11.9 Hz, 1.08H), 4.71e4.66 (m, 1.71H), 4.63 (d, J ¼ 12.0 Hz,
1.17H), 4.60 (s, 2.88H), 4.58e4.51 (m, 1.58H), 4.28 (dt, J ¼ 7.8, 3.8 Hz,
0.44H), 4.20e4.13 (m, 1.96H), 4.12e4.07 (m, 1.28H), 4.05e3.97 (m,
0.54H), 3.74e3.57 (m, 4.19), 2.00e1.85 (m, 2.92H), 1.84e1.72 (m,
3.19H), 1.63e1.55 (m, 1.57H), 1.50e1.13 (m, 7.94H); 13C NMR
CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68 mL, 2.0
eq). The flask was sealed and the mixture stirred at room temper-
ature for 18 h. The mixture was filtered through a pad of celite,
washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo. The
crude product was purified by flash column chromatography on
silica gel (eluting with petroleum ether/ethyl acetate 10/1 to 6/1) to
give two components (A and B), successively.
Component A was identified to be 2,3,4,6-tetra-O-benzyl-a,b-D-
glucopyranosyl fluoride 9 (15 mg, 15%) as a colorless syrup. The
spectral data of 9 was identical with the literature data [19c].
(126 MHz, cdcl3)
d 138.41, 138.26, 138.17, 138.12, 137.89, 137.78,
128.60, 128.49, 128.47, 128.45, 128.43, 128.38, 128.36, 128.16, 128.12,
127.98, 127.94, 127.88, 127.87, 127.82, 127.80, 127.77, 127.73, 127.69,
127.66, 127.60, 104.14, 98.81, 88.87, 84.07, 83.77, 83.64, 80.11, 80.04,
75.95, 74.96, 73.41, 73.38, 73.05, 72.34, 72.22, 72.13, 71.99, 69.84,
33.79, 33.73, 31.83, 31.72, 25.79, 25.68, 24.52, 24.33, 24.28, 24.14;
Component B was identified to be 2,3,4,6-tetra-O-benzyl-
glucopyranosyl-(141)-2,3,4,6-tetra-O-benzyl- -glucopyranoside 8
(84 mg, aa ab
D-
HRMS (ESI) calcd for
525.2611.
C
32H38NaO5 [MþNa]þ 525.2617, found
D
/
/
bb ¼ 24/15/1, 85%) as a colorless syrup. The spectral
The reaction of donor 1b and acceptor 4 mediated by NfF
(Scheme 3). A 25 mL glass Schlenk flask fitted with a resealable
Teflon valve was equipped with a magnetic stir bar and charged
with glycosyl donor 1b (0.189 mmol, 93 mg), glycosyl acceptor 4
(0.28 mmol, 74 mg, 1.5 eq), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq),
and 3 Å molecular sieves (300 mg), then, under argon protection,
data of 8 was identical with the literature data [25a].
Self-condensation of donor 1c mediated by NfF. A 25 mL glass
Schlenk flask fitted with a resealable Teflon valve was equipped
with a magnetic stir bar and charged with glycosyl donor 1c
(0.19 mmol, 82 mg), Cs2CO3 (0.370 mmol, 121 mg, 2.0 eq), and 3 Å
molecular sieves (300 mg), then, under argon protection, dry
dry CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68
mL,
CH2Cl2 (2.0 mL) was added, followed by NfF (0.370 mmol, 68 mL, 2.0
2.0 eq). The flask was sealed and the mixture stirred at room
temperature for 18 h. The mixture was filtered through a pad of
celite, washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo.
The crude product was purified by flash column chromatography
on silica gel (eluting with petroleum ether/ethyl acetate 15/1 to 4/1
to 3/1) to give four components (A-D), successively.
eq). The flask was sealed and the mixture stirred at room temper-
ature for 24 h. The mixture was filtered through a pad of celite,
washed with CH2Cl2 (2 mL ꢂ 3) and concentrated in vacuo. The
crude product was purified by flash column chromatography on
silica gel (eluting with petroleum ether/ethyl acetate 6/1 to 5/1) to
give two components (A and B), successively.
Component A was identified to be nonaflated acceptor 1,2:3,4-
Component A was identified to be 2,3,4-tri-O-benzyl-
a-L-
di-O-isopropylidene-6-O-nonafluorobutanesulfonyl-
actopyranose 6 (87 mg, 56%) as a colorless syrup: 1H NMR
(500 MHz, CDCl3)
a
-
D
-gal-
rhamnopyranosyl-(141)-2,3,4-tri-O-benzyl- -rhamnopyrano-
side 10aa (57 mg, 70%) as a colorless syrup. The spectral data of
10aa was identical with the literature data [25b].
a-L
d
5.53 (d, J ¼ 4.9 Hz, 1H), 4.71e4.57 (m, 3H), 4.35
(dd, J ¼ 5.1, 2.6 Hz, 1H), 4.27e4.21 (m, 1H), 4.11 (t, J ¼ 6.2 Hz, 1H),
Component
rhamnopyranosyl-(141)-2,3,4-tri-O-benzyl-
side 10ab (23 mg, 28%) as a colorless syrup. [
CH2Cl2); 1H NMR (500 MHz, CDCl3)
7.39e7.21 (m, 29H), 4.96 (d,
B
was identified to be 2,3,4-tri-O-benzyl-
a-L-
1.51 (s, 3H), 1.44 (s, 3H), 1.36e1.29 (m, 6H); 13C NMR (126 MHz,
b-L
a
-rhamnopyrano-
25
CDCl3)
d
110.28, 109.27, 96.30, 75.29, 70.84, 70.57, 70.43, 66.32,
]
¼ 12.3 (c 0.51,
D
25.98, 25.96, 24.96, 24.46; 19F NMR (471 MHz, CDCl3)
d
ꢃ80.81 (t,
d
J ¼ 9.7 Hz), ꢃ110.73 (t, J ¼ 14.4 Hz), ꢃ121.32 to ꢃ121.52 (m), ꢃ125.94
to ꢃ126.06 (m); HRMS (ESI) calcd for C16H19F9NaO8S [MþNa]þ
565.0555, found 565.0549.
J ¼ 11.2 Hz, 1H), 4.93 (d, J ¼ 10.8 Hz, 1H), 4.89 (d, J ¼ 1.8 Hz, 1H), 4.80
(d, J ¼ 12.5 Hz, 1H), 4.77 (d, J ¼ 12.5 Hz, 1H), 4.72 (d, J ¼ 12.5 Hz, 1H),
4.70e4.61 (m, 4H), 4.58 (d, J ¼ 11.9 Hz, 1H), 4.57e4.49 (m, 2H), 4.41
(s, 1H), 4.10e4.04 (m, 1H), 3.92 (dd, J ¼ 9.4, 3.1 Hz, 1H), 3.78 (d,
J ¼ 2.9 Hz, 1H), 3.69 (dd, J ¼ 3.1, 1.8 Hz, 1H), 3.63 (t, J ¼ 9.5 Hz, 1H),
3.59 (t, J ¼ 9.3 Hz, 1H), 3.42 (dd, J ¼ 9.4, 2.9 Hz, 1H), 3.30 (dd, J ¼ 9.2,
6.2 Hz, 1H), 1.33 (d, J ¼ 6.1 Hz, 3H), 1.29 (d, J ¼ 6.5 Hz, 3H); 13C NMR
Component
benzyl- - glucopyranosyl fluoride 7 (12 mg,
pale yellow solid: 1H NMR (500 MHz, CDCl3)
7.40e7.23 (m, 12.9H),
B
was identified to be 6-O-acetyl-2,3,4-tri-O-
a
,b
-D
a/b
¼ 5/1, 12%) as a
d
5.52 (dd, J ¼ 53.0, 2.7 Hz, 0.21H), 5.28 (dd, J ¼ 52.7, 6.5 Hz, 1.0H),
4.99 (d, J ¼ 10.8 Hz, 0.22H), 4.91 (d, J ¼ 11.0 Hz, 0.81H), 4.89e4.83
(m, 1.66H), 4.78 (d, J ¼ 11.0 Hz, 0.84H), 4.70 (d, J ¼ 11.2 Hz, 0.95H),
4.58 (d, J ¼ 10.9 Hz, 0.89H), 4.38 (dd, J ¼ 12.0, 2.2 Hz, 0.87H), 4.28
(dd, J ¼ 10.2, 3.2 Hz, 0.39H), 4.22 (dd, J ¼ 12.1, 4.8 Hz, 0.91H), 4.01 (d,
J ¼ 9.2 Hz, 0.36H), 3.77e3.50 (m, 3.26H), 2.05 (s, 2.02H), 2.03 (s,
(126 MHz, cdcl3)
d 139.07, 138.76, 138.67, 138.57, 138.43, 138.35,
128.51, 128.49, 128.48, 128.43, 128.40, 128.27, 128.23, 128.03, 127.87,
127.84, 127.81, 127.76, 127.71, 127.66, 127.53, 100.31, 98.92, 82.52,
80.68, 80.07, 79.88, 75.55, 75.46, 75.12, 74.21, 74.01, 73.02, 72.83,
72.33, 71.94, 69.19, 60.53, 18.11, 17.78; HRMS (ESI) calcd for
0.43H); 13C NMR (126 MHz, CDCl3)
d
170.80, 138.20, 137.69, 137.62,
C
54H58NaO9 [MþNa]þ 873.3979, found 873.3973.
128.75, 128.68, 128.64, 128.61, 128.30, 128.25, 128.22, 128.19, 128.16,
Self-condensation of donor 11 mediated by NfF. A 25 mL glass
128.13, 128.01, 127.98, 109.66 (d, J ¼ 216.9 Hz), 83.56 (d, J ¼ 10.5 Hz),
Schlenk flask fitted with a resealable Teflon valve was equipped
6