Chemistry Reference
In-Depth Information
-Fluorination of aldehydes
α
O
Me
N
i) 20 mol % cat.*, THF,
i
-PrOH, -10°C
O
PhO
2
S
SO
2
Ph
R
Catalyst =
Me
Me
N
HO
(eq 1)
R
H
H
F
F
ii) NaBH
4
Ph
•DCA
54-96% yield
91-99% ee
α
-Chlorination of aldehydes
O
O
Me
Cl
O
Cl
N
5 mol % cat.*
O
Catalyst =
Me
Me
R
(eq 2)
Cl
R
H
H
H
Acetone, -30°C
Cl
Cl
Cl
Ph
•TFA
Cl
71-92% yield
80-95% ee
α
-Bromination of aldehydes
O
i) 20 mol % cat.*, CH
2
Cl
2
, pentane
H
2
O, 23°C or -24°C
t
-Bu
t
-Bu
O
R
Catalyst =
Ph
HO
Ph
(eq 3)
H
R
H
ii) NaBH
4
Br
•PhCO
2
H
Br
Br
72-95% yield
68-96% ee
α
-Iodination of aldehydes
O
O
20 mol % cat.*
O
Catalyst =
Ph
R
Ph
(eq 4)
N
I
H
R
H
H
CH
2
Cl
2
, pentane, -24°C
I
•PhCO
2
H
O
30-78% yield
60-89% ee
Scheme 2A.16.
Enamine - catalyzed
α
- halogenation of aldehydes.
O
R
1
O
2
C
i) 10 mol % cat.*, CH
2
Cl
2
, RT
O
N
N
NHCO
2
R
1
Catalyst =
O
N
CO
2
H
R
H
H
ii) NaBH
4
iii) NaOH
CO
2
R
1
R
57-92% yield
89-95% ee
Scheme 2A.17.
Enamine - catalyzed
α
-amination of aldehydes using azodicarboxylates.
Ph
Ph
i) 10 mol % cat.*, THF, 0°C
Ph
OH
OH
O
O
Catalyst =
N
R
N
OH
H
Ph
ii) NaBH
4
R
NH
70-90% yield
96-99% ee
OH
Ph
Ph
Scheme 2A.18.
Enamine - catalyzed
α
-amination of aldehydes using nitrosobenzene.
