吡咯,呋喃,噻吩

S
Ac2O/AcOH
S 60 %
NO2 + S 10 % NO NO2 + N H 13 %
2
AcONO2 O oC
N H
Ac2O/AcOH
N H 51 %
AcONO2 O -5 - -30oC O +
H NO2
H AcO O
H NO2
Pyridine
O N
NO2
H
Sulfonation reaction of pyrrole、furan and thiophene
+
O
2H2
Ni 50oC
O
+
N H
2H2
Ni 200--250oC
N H
+
S
2H2
MoS2 or Na,Hg/EtOH
S
Diels-Alder reaction
O O + O O O O O O 90 %
O +
COOCH3 H3C N CH3 + COOCH3
O
76 %
N COCH3 CH3 COOCH3 H3C COOCH3
The ability to draw electronicO(3.5)>N(3.0)>S(2.6) the ability of conjugate N > O > S;In general the ability to Contribution electronic N > O > S
the activity of Electrophilic substitution reaction are as follow:
Electrophilic aromatic substitution more reactive than benzene,Substitution occurs preferentially at C-2, if both positions adjacent to the heteroatom are occupied, substitution will take place at C-3.
——周琪
• Electrophilic substitution of pyrrole、furan and thiophene • Catalytic hydrogenation of pyrrole、furan and thiophene • Diels-Alder reaction • The acidity of H in the N of pyrrole
The halogenating reaction of pyrrole、furan and thiophene
Br2, 0℃
Cl O
Cl
+ O
Cl
Cl2 -40℃ O
Br O O 稀释 O
(86 %)
Br2 AcO H
Br S
(78 %)
S
I2, HgO C6H6, 0℃
I S
Iodine is not activily enough so it need a catalyst
The acidity of H in the N of pyrrole
+
KOH N + K
+
H2O
பைடு நூலகம்
N H
CH3COCl 80oC
N COCH3
>150oC
N COCH3
CH3I 60oC
N K N CH3
>150oC
N H CH3
(1)CO2 (2)H2O
N H COOH
CHCl3 KOH
N H CHO
N H
>
O
>
S
>
Relative resonance energies of some aromatic compounds
For thiophene and pyrrole it`s easy to be substitute but hard to take a Nucleophilic addition action ,while for furan it can take a Nucleophilic addition on the effect of Strong nucleophilic reagent
O N H C C H3
A l C3l
Al C l 3
COCH3
H 3C
COOC3 H COOC3 H
CH3
Thiophene ia hardly to react with dienes
60 - 120℃
H3C
S
CH3 + NC-C
C-CN
S
CH3 CN
-S
CH3 CN CN
H3C CN CH3
Br Br N H
Br Br
Br2, 0℃ EtO H SOCl2 (1 mol)
N H
Et2O, 0℃
Cl N H
(80 %)
Nitration reaction of pyrrole、furan and
thiophene
O O CH3COCCH3 + HNO3
AcONO2 O oC
O CH3CONO2 + CH3COOH NO2
+ Ac 2O
150 - 200 ℃
O N H
O Ph C C l
N H
CCH3
(60 %)
Na
N H
或 NaOH(浓)
(70 %) N COPh
N Na+
+ Ac2O O
BF3 O
O CCH3
O
Ac2O 与 Al C 3 的混合体系 l
S
S
CCH3
Catalytic hydrogenation of pyrrole、 furan and thiophene
O
ClCH2CH2Cl
SO3-
N H
O
+
N SO3
r. t. 3 days N H
ClCH2CH2Cl Ba(OH)2
-
O3S
O
SO3-
N H
2
S
+
Ba
2+
N
SO3
r. t.
S
SO3
100 oC
HCl N H SO3- N H N H SO3H
N H
+
N SO3
Fourier acyl chemical reaction
Electrophilic substitution of pyrrole、 furan and thiophene
Pyrrole, furan, and thiophene are five-membered-ring eterocycles. Pyrrole, furan, and thiophene are aromatic because they are cyclic and planar, every carbon in the ring has a p orbital, and the πcloud contains three pairs of π electrons
For example
6
Mechanism
substituted at C-2
E+ A H A E A E A E
取代
满足八隅体 贡献大
- H+ A E
中间体有三个主要共振式 较稳定
substituted at c-3
E E A
+
E H
A
A
满足八隅体 贡献大
E - H+ A
中间体只有二个主要共振式 较不稳定