Chemistry Reference
In-Depth Information
O
N
N
O
t
-Bu
t-
Bu
O
2
S
N
Ph
O
O
N
N
t
-Bu
toluene, reflux
t
-Bu
-SO
2
N
Ph
N
Ph
O
+
N
N
N
Ph
S
N
N
t
-Bu
O
O
O
t
-Bu
87%
O
O
t
-Bu
t
-Bu
t
-Bu
t
-Bu
O
t
-Bu
t
-Bu
O
Ph
KOH, MeOH
t
-Bu
N
-N
2
Ph
[O]
N
N
N
N
N
HN
N
NH
r.t.
N
N
80%
N
N
O
HN
N
t
-Bu
H
O
102
103
Scheme 98
Synthesis of 4,5-di-
t
-butylpyridazine through Diels-Alder cycloaddition of 3,4-di-
tert
-butylthiophene 1,1-dioxide with 4-phenyl-1,2,4-triazoline-3,5-dione (PTAD) [
120
]
O
X
O
t
-Bu
t-
Bu
O
O
O
O
S
t
-Bu
t
-Bu
-SO
2
O
X
X
+
X
S
O
O
t
-Bu
O
t
-Bu
O
O
104
t
-Bu
t
-Bu
t
-Bu
t
-Bu
O
O
O
X
Yield (%)
X
Yield (%)
X
X
O
NPh
73
58
X
O
NPh
25
40
O
+
O
O
O
X
O
105
106
Scheme 99
Isomeric bis-adducts formed through Diels-Alder cycloaddition of 3,4-di-
tert
-
butylthiophene 1,1-dioxide with maleic anhydride and
N
-phenylmaleimide [
110
]
O
O
O
Cl
Cl
Cl
Cl
-SO
2
reflux
NR
NR
SO
2
NR
+
S
Cl
Cl
O
O
O
O
O
O
O
O
NR
R
Solvent
xylene
benzene
Yield (%)
CCl
CCl
O
n-
Bu
56.5%
81%
RN
NR
p
-nitrophenyl
O
O
Scheme 100
Bis-adducts formed through Diels-Alder cycloaddition of 3,4-dichlorothiophene
1,1-dioxide with
N
-butyl- and
N
-
p
-nitrophenyl maleimides [
89
]
