Chemistry Reference
In-Depth Information
O
O
H
R
1
N
Δ
OH
R
2
R
2
R
1
O
PhH, 5-10 h
ascorbic acid
N
OH
R
2
R
2
243
244
245
(36-93%)
O
O
R
1
R
1
H
+
(cat)
TFAA
R
2
N
O
R
2
R
2
TFA, rt
N
CF
3
R
2
246
O
247
Entry
R
1
R
1
248
(%)
a
245
(%)
O
R
1
1
2
3
4
H
H
Me
Cl
H
H
Me
Me
52
93
36
70
87
69
91
69
-H
+
R
2
N
R
2
H
248
a
Yield from
245
.
SCHEME 10.39.
Although the photolysis of aryl azides has traditionally been employed as a
route to nitrenes, when conducted in the presence of Brønsted acids, aryl nitrenium
ions are generated via protonation.
92
Taking advantage of this mild route to
nitrenium ions, Swenton and Hyatt found that photolysis of biaryltetrazoles
256
P
4
O
10
-H
+
C
6
H
6
reflux
N
N
OH
N
R
R
R
249;
R = Bz; Ts
250
251;
R = Bz (70%)
252;
R = Ts (55%)
OH
O
2
N
H
N
TFA
Zn, TFA
C
6
H
6
0
°
C, 2 h
H
255
(38-45%)
253
254
SCHEME 10.40.
