Chemistry Reference
In-Depth Information
(a) Synthesis by method A
H
Bus
O
-
Bus
O
-
N
DBU (
1
)
N
Me
+
Me
S
+
S
+
R
EtO
2
C
DCM
Ph
EtO
2
C
-
Ph
R
Bus = O
2
S
t
Bu
Bus
cis
-aziridine (%)
trans
-aziridine (%)
R
sulfoxide (%)
O
N
+
S
Ph
82 (29% ee)
5 (30% ee)
79
R
Ph
Me
EtO
2
C
i
Pr
76 (92% ee)
6 (26% ee)
71
cylohexyl
75 (71% ee)
4 (48% ee)
70
(a) Synthesis by method B
O
-
Me
Bus
S
+
O
1. DBU (
1
), DCM
Ph
N
+
S
Bus
2.
Ph
Me
EtO
2
C
N
n
n
EtO
2
C
cis
-aziridine (%)
trans
-aziridine (%)
sulfoxide (%)
n
2
42 (76% ee)
28 (56% ee)
81
3
41 (78% ee)
26 (57% ee)
76
4
75 (71% ee)
30 (25% ee)
70
Scheme 3.31
DBU (1) mediated aziridination through allylsulfoxonium ylides
A combination of lithium bromide (LiBr) and DBU (1) catalyses regio- and stereospe-
cific cycloaddition [54]. Imines of aminopyradazino[1,2-a][1,2]diazepine react with a
range of achiral and chiral dipolarophiles in the presence of LiBr and DBU (1) in MeCN to
afford enantiopure spiro-cycloadducts in excellent yield via lithio azomethine ylides [54b]
(Scheme 3.34).
catalyst
i
PrCOO
O
O
O
1. DBU (
1
) (1 equiv)
rt, 96 h
Ar = 3,5-(CF
3
)
2
C
6
H
3
Ar
OMe
H
+
OMe
HO
N
O
Ar
2. (
i
PrCO)
2
O (1.5 equiv)
catalyst, DCM
-78 ˚C, 24 h
OMe
OMe
N
25% (89% ee)
(56% conversion)
N
Scheme 3.32
DBU (1) catalysed Baylis-Hillman reaction and kinetic resolution
