Chemistry Reference
In-Depth Information
41
(1 mol %)
2 M KCN
aq
(1.5 equiv
)
SO
2
Mes
SO
2
Mes
N
H
N
Toluene, 0°C
2-8 h
R =
c
-Hex
c
-Oct
(CH
3
)
2
CH
PhCH
2
CH
2
t
-Bu
R
H
R
CN
Ar
: 89%, 95% ee
: 88%, 97% ee
: 85%, 93% ee
: 81%, 90% ee
: 94%, 94% ee
Ar
Me
I
N
Me
Ar
41
(Ar = 4-CF
3
-C
6
H
4
)
Ar
Scheme 2C.22.
O
(
S
)-
42
(3 mol %)
O
CO
2
t
-Bu
Boc
N
CO
2
t
-Bu
+
N
Boc
K
2
HPO
4
Toluene
-20°C, 14 h
N
NH
Boc
Boc
99%, 91% ee
O
O
(
S
)-
42
(3 mol %)
CO
2
t
-Bu
Boc
Boc
CO
2
t
-Bu
+
Boc
N
N
N
N
Boc
K
2
HPO
4
Toluene
-20°C, 40 h
N
NH
O
O
Boc
Boc
99%, 92% ee
Ar
-
Br
CF
3
+
Bu
Bu
P
Ar =
CF
3
(
S
)-
42
Ar
Scheme 2C.23.
2C.9. ION PAIR CATALYSTS
2C.9.1. Ammonium Fluorides
Quaternary ammonium fl uorides, particularly tetraalkylammonium fl uorides, have been
widely recognized as a convenient, organic-soluble source of naked fl uoride ion. Their
utility in modern organic synthesis has been well documented on numerous occasions
taking advantage of either the nucleophilic affi nity of fl uoride ion to a silicon atom or
its eminent basicity in aprotic solvents [56]. The former property enables the fl uoride-
mediated generation of nucleophiles from organosilicon compounds, and the latter
