Chemistry Reference
In-Depth Information
The reaction of dienyl carbonate
14
using
ent
-
12
was investigated by Helmchen and
others (Scheme 5.5). High regioselectivity in favor of the desired internal substitution
product
15
was obtained [9a]. The aminations provided ee values up to 97%. Several
N
-nucleophiles having the removal protecting groups on nitrogen atom were also studied
[9d,f]. For the iridium-catalyzed enantioselective allylic amination of cinnamyl carbonate
10
, new ligand
17
was reported by Alexakis and others [10]. Ligand
17
with fi xed atro-
poisomerism gave an excellent result, even slightly better than Ligand
12
(Scheme 5.4 ).
BnNH
2
NHBn
[Ir(COD)Cl]
2
+
Ph
OCO
2
Me
Ligand
ent
-
12
Ph
Ph
NHBn
S
14
15
(61%, 97% ee)
16
THF
Regioselectivity (
15
:
16
= 99:1)
Ar
n
-Hexylamine
n
-Hexyl
O
H
N
[Ir(COD)Cl]
2
PN
Ph
OCO
2
Me
Ph
Ligand
17
THF
O
Ar
10
11a
(89%, 98% ee)
Ligand
17
: Ar =
o
-MeO-C
6
H
4
Regioselectivity (98:2)
Scheme 5.5.
Takemoto, Miyabe, and others reported that the iridium complex of pybox
20
cata-
lyzed the allylic amination to form the branched product with good enantioselectivity
(Scheme 5.6) [11]. In the presence of CsOH·H
2
O, the reaction of phosphate
18
with
BnONHBz proceeded smoothly to give the branched product
19
with 96% ee.
BnONHBz
NBzOBn
[Ir(COD)Cl]
2
OP(O)(OEt)
2
Ligand
20
O
O
N
CsOH·H
2
O
N
N
CH
2
Cl
2
Ph
Ph
18
19
(95%, 96% ee)
Regioselectivity (>95:5)
Ligand
20
Scheme 5.6.
Direct iridium-catalyzed synthesis of primary allylic amines from allylic alcohols was
studied by Carreira and others (Scheme 5.7) [12]. In these reactions, sulfamic acid
22
(H
2
NSO
3
H) serves not only as a nitrogen source but also as an
in situ
activator of
hydroxy group of allylic alcohols. The allylic amination of allylic alcohol
21
using ligand
24
occurred with high regioselectivity to give (
S
) - 1 - cyclohexylprop - 2 - en - 1 - amine hydro-
chloride in 70% yield and 70% ee.
