Chemistry Reference
In-Depth Information
Table 9.7
Diels-Alder reaction of N-crotonyloxazolidinone and cyclopentadiene
OO
e
OO
25 mol%
catalyst
OO
e
O
N
+
ON
e
ON
Me
Me
Me
Me
Me
Me
B
A
Me
run
catalyst
temp (
o
C)
time (h)
yield (%)
ratio (A / B)
thiourea
S
O
1
2
3
4
non
AlCl
3
TiCl
3
thiourea
96
1
1
48
55
95
92
78
36 / 64
92 / 8
89 / 11
91 / 19
Ar
Ar
N
H
N
H
ONO
-78
o
C
-78
o
C
23
o
C
Me
Ar = 3,5-(CF
3
)
2
-C
6
H
3
Me
(a) Double hydrogen bonding for adduct A
S
S
Ar
Ar
Ar
Ar
N
N
N
N
HH
HH
OO
OO
and / or
ON
e
ON
e
Me
Me
Me
Me
(b) Single hydrogen bonding for adduct B
S
Me
Ar
Ar
N
N
Me
O
HH
Ar
H
O
and / or
ONO
N
ONO
H
S
N
Me
Ar
Me
Me
Me
Figure 9.6
Possible transition states of the thiourea catalysed reaction for (a) adduct A and
(b) adduct B
