C-Glycosylation
3.8
765
⊡ Table 2
[19]
Entry Sugar
Nucleophile
Hemiacetal Reduction
Product
Ref.
Silane, Lewis acid
Yield (α/β)
1
Glucose
MeMgBr
90%
Et 3 SiH, TMSOTf
81% (0/100)
[19a,b]
2
ND
Et 3 SiH, BF 3 ·OEt 2
85% (10/90) a
[19c]
3
82%
Et 3 SiH, TMSOTf
79% (10/90)
[19a,b]
4
ND
Et 3 SiH, BF 3 ·OEt 2
49% (0/100) a
[19d]
5
ND
Et 3 SiH, BF 3 ·OEt 2
74% (0/100)
[19e]
6
Quant
Et 3 SiH, BF 3 ·OEt 2
72% (0/100)
[19f]
7
PhLi
85%
Et 3 SiH, BF 3 ·OEt 2
80% (1/4)
[19g,h]
8
ND
Et 3 SiH, BF 3 ·OEt 2
77% (0/100) a
[19g]
9
ND
Et 3 SiH, BF 3 ·OEt 2
72% (0/100) a
[19c]
10
74%
Et 3 SiH, BF 3 ·OEt 2
99% (0/100)
[19i]
11
Galactose
ND
Et 3 SiH, BF 3 ·OEt 2
81% (0/100) a
[19j]
12
ND
Et 3 SiH, BF 3 ·OEt 2
76% (10/90) a
[19c]
13
ND
Et 3 SiH, BF 3 ·OEt 2
50% (0/100) a
[19d]
14
91%
Et 3 SiH, BF 3 ·OEt 2
71% (0/100) b
[19k]
15
75% c
Et 3 SiH, TMSOTf
96% (0/100)
[19l]
16
ND
Et 3 SiH, BF 3 ·OEt 2
79% (0/100) a
[19c]
17
Mannose
MeMgBr
86%
Et 3 SiH, TMSOTf
68% (22/78)
[19a,b]
18
ND
Et 3 SiH, BF 3 ·OEt 2
67% (1/1) a
[19c]
19
ND
Et 3 SiH, TMSOTf
61% (33/67) a
[19a,b]
20
93%
Et 3 SiH, BF 3 ·OEt 2
77% (1/2.5) b
[19k]
21
–
( T M S ) 3 SiH, BF 3 ·OEt 2 76% (0/100) b
[19m]
22
PhLi
85%
Et 3 SiH, TMSOTf
53% (0/100)
[19b]
23
78% c
Et 3 SiH, TMSOTf
97% (0/100)
[19l]
24
ND
Et 3 SiH, BF 3 ·OEt 2
66% (3/1) a
[19c]
a : 2-step yield; b : after removal of TMS with TBAF; c : product was the corresponding acetate