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Crown Ether Catalyzed Reduction of Aromatic Nitro Compounds to Give Amines.

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C O M M U N I CAT1 0 N S
We assume the reaction to proceed as follows: The crown
ether ( I ) bonds the K f ion of KOH to give the unsolvated
and highly reactive OH- ion. This species attacks Fe3(C0)12
in the organic phase, affording [Fe3(CO), 1]2-[31 which yields
the ions OH- and [HFe3(CO)11]- with water. The latter
ionic product reduces the nitro compound.
To a mixture of nitroarene (1 .O mmol), Fe3(CO)1 (0.5mmol),
and [18]crown-6 (0.1 mmol) in benzene (IOml), is added 1 N
K O H (10ml). The solution was vigorously stirred at room
temperature for 1.5-2.5 hours (N2 atmosphere). The layers
were separated and the aqueous layer was washed with ether;
the washings are added to the separated organic layer, dried
(MgS04), and evaporated in uacuo. The residue is chromatographed on a silica gel column using benzene or benzene/ether
as the eluant.
Crown Ether Catalyzed Reduction of Aromatic Nitro
Compounds to Give Amines"]
By Howard Alper, Daniel Des Roches, and Herve'des Abbayes[*]
Aromatic nitro compounds are reduced to amines by refluxing with an equimolar amount of Fe3(C0)12in benzene/methanol for 10 to 17h[21.We have found that this reaction is
catalyzed by the crown ether [18]crown-6 ( 1 ) in the presence
of 1 N KOH. Only half the amount of Fe3(C0)12 is needed,
and the reaction proceeds within 1.5 to 2.5 h on stirring of
the reactants in benzene at room temperature. Work-up is
simpler and the yields are just as good (see Table 1).
CAS Registry numbers:
( 1 ), 17455-13-9; aniline, 62-53-3; p-toluidine, 106-49-0; p-anisidine, 104-94-9:
p-chloroaniline, 106-47-8; 2-fluorenylamine, 153-78-6; nitrobenzene, 98-95-3;
1 -methyl-4-nitrobenzene, 99-99-0: I -methoxy-4-nitrobenzene, 100-17-4; I
chloro-4-nitrobenzene, 100-00-5; 2-uitro-9H-fluorene, 607-57-8: Fe,(C0)12.
[I] This work was supported by the National Research Council of Canada.
[2] J . M . Lundrsbrrg, L. Kurz, and C. O / . w i , J. Org. Chem. 37, 930 (1972).
131 W Hiebrr and G . Breiidel, Z . Anorg. Allg. Chem. 289, 338 (1957).
Synthesis and Dynamic Behavior of Pentamethylcyclopentadienyl boranes[**I
By Peter Jutzi and Arnulf Seufert"]
The pentamethylcyclopentadienylboranes described here
are the first representatives of this type of compounds in
which boron is bound to the cyclopentadiene ring in the
ally1 position. The preferred vinyl isomers in all previously
known cyclopentadienylborannes['l cannot be formed here
owing to the high activation energy of the 1,2-methyl shift.
Synthesis of the surprisingly thermally stable dichloro(pentamethylcyclopentadieny1)borane ( 2 ) has been achieved by
Table I . Reaction times and yields
Amine formed
Received: August 30, 1976;
revised: September 30, 1976 [ Z 574 IE]
German version: Angew. Chem. 89, 43 (1977)
Reaction time
[a] 3 % in the absence or ( I ).
[b] 2 "/, in the absence of ( I ).
[c] 33 %, in the absence of H20.
The nitro compound was almost completely recovered when
the reaction was repeated in the absence of the crown ether
( 1 ) (see Table I), and the use of solid KOH, i. e. the absence
of water, gave the amines in significantly lower yields.
"7, Dr. D. Des Roches, and
Dr. H. des Abbdyes ["*I
Department of Chemistry, University of Ottawa
Ottawa, Ontario, Canada K I N 6N5
[ + ]To whom correspondence should be addressed.
[**I France-Canada exchange scientist.
[*] Prof. Dr. H. Alper
Anyrw. Chem. Inr. E d Enyl. 16 ( 1 9 7 7 ) No. I
[*] Doz. Dr. P. Jutzi and Dip1.-Chem. A. Seufert
lnstitut fur Anorganische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (Germany)
[**] This work was supported by the Fonds der Chemischen Industrie
and the Deutsche Forschungsgemeinschaft.
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crown, compounds, ethers, reduction, give, nitra, amines, aromatic, catalyzed
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