Chemistry Reference
In-Depth Information
EtO
2
C
CO
2
Et
PA
1k
(2 mol %)
Benzene, 60°C
N
R
H
N
H
R
(1.0 eq)
(2.4 eq)
16 examples
54-95% yield
88-99% ee
O
EtO
2
C
CO
2
Et
O
R
1
PA
1k
(0.1 mol %
)
Benzene, 60°C
R
1
N
R
H
H
R
(1.0 eq)
(1.25 eq)
6 examples
92-95% yield
98->99% ee
S
EtO
2
C
CO
2
Et
S
PA
1k
(1 mol %)
Benzene, 60°C
N
R
H
N
H
R
(1.0 eq)
(1.25 eq)
6 examples
50-78% yield
93->99% ee
O
O
EtO
2
C
CO
2
Et
O
O
R
1
PA
1k
(1 mol %)
Benzene, 60°C
R
1
N
R
H
H
R
(1.0 eq)
7 examples
(1.25 eq)
55-92% yield
90->99% ee
R
1
R
1
EtO
2
C
CO
2
Et
PA
1j
(5 mol %)
Benzene, 50°C
R
2
R
3
H
R
2
R
3
H
N
10 examples
(4 eq)
47-84% yield
84-92% ee
Scheme 3.44.
the synthesis of biologically active tetrahydroquinoline alkanoids: (+)-galipinine, (+)-cus-
pareine, and (+) - angustureind (Scheme 3.44 ) [74] .
List and coworkers achieved catalytic asymmetric reductive amination of α - branched
aldehydes and
p
-anisidine with Hantzsch ester as a hydrogen source via dynamic kinetic
resolution to afford β-substituted amines in excellent yields and good to excellent enan-
tioselectivities (Scheme 3.45) [76]. With the successful reduction of imines with Hantzsch
esters, they developed the highly enantioselective synthesis of pharmaceutically relevant
3 - substituted cyclohexylamines from 2,6 - diketones via an aldolization - dehydration -
conjugate reduction-reductive amination cascade reaction catalyzed by a chiral phos-
phoric acid (Scheme 3.46 ) [77] .
