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Electrophilic Amination of Cyclopentadienyllithium Compounds.

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have recently been supplemented by selenophenol['] and
transition metal hydrides[''. Reaction with typical hydride
reagents such as LiAlH4i31,LiAl(OR)3H[31,and NaBH4i41are
usually sluggish.
In this paper we wish to report that hydrogen telluride[']
generated in situ has a high reducing ability toward nitroarenes [Table 1, eq. (I)].
ArylNOz + A12Te3+ 4 H 2 0 + ArylNH,
+ 2AI(OH), + 3Te
(1)
Table 1. Yields.obtained in the reduction of some aromatic nitrogen compounds
with AI2Te3/H20,for reaction conditions, see Experimental.
Reactant
Ar-NH2
Yield [%]
CJisN02
C&LN02
ChHsN02
p-MeC6H4N02
m-MeC,H4N02
p-CIC6H4NO2
p-BrC6H4NO2
p-MeOC6H4N02
C6H5N0
C6H,NHOH
C6HsN=-NCeHs [d]
CeHsN=N(O)C6Hs [d]
90
63 la1
45 Icl
92
94
60
47
60
16
98
4
6
[a] T = 20 "C. [b] Not determined. [c] T =
Ar-NHNH-Ar
Yield [%]
trace
M
lbI
Electrophilic Amination of Cyclopentadienyllithium
Compounds[**]
By Michael Bernheim and Gernot Bochei"
Dedicated to Professor Karl Dimroth on the occasion of
his 70th birthday
Although cyclopentadienyl compounds have found extraordinarily wide application as ligands of organometallic
complexes and as synthons for natural products, e.g. prostaglandins, virtually nothing is known about cyclopentadienylarnined'l. We report here on the entry to this class of compounds by electrophilic amination of cyclopentadienyllithium compounds.
Reaction of cyclopentadienyllithium (I)121
with N,N-dimethyl-0-(methylsulfony1)hydroxylamine (2)131 in tetrahydrofuran (THF) at - 20 "C afforded N,N-dimethyl-1,3-cyclopentadienylamine (3b) in 47% yield (see Procedure).
PI
[bl
[bl
PI
[bl
63
I
96
86
- 15 "C. [d] 0.5 mmol of reactant.
It is noteworthy that nitrosobenzene gives hydrazobenzene
as a major product while phenylhydroxylamine yields aniline quantitatively. This result might be taken to suggest that
nitrosobenzene is not the intermediate in the reduction of nitrobenzene to aniline. Alternatively, however, the intermediacy of nitrosobenzene in the reduction of nitrobenzene is
accommodated, if transiently formed nitrosobenzene undergoes rapid further reduction to give phenylhydroxylamine
before the condensation161 with phenylhydroxylamine. The
reductions of both azoxybenzene and azobenzene by HzTe
afford good yields of hydrazobenzene, indicating that neither
the azo nor the azoxy compound is the probable intermediate in the reduction of nitrobenzene.
Experimental
Powdered A12Te3(674 mg, 2 mmol), stored under N2 in
the dark, is added to a tetrahydrofuran (10 ml) solution of nitrobenzene (123 mg, l mmol) under N2 at room temperature.
Then the temperature is raised to 66 "C. To the vigorously
stirred reaction mixture is slowly added an excess of water
(0.43ml, 24 mmol) dropwise by a syringe over a period of 40
min. The reaction mixture is refluxed for another 20 min and
worked up. The yield of aniline is 90% (GC, 'H-NMR, and
IR).
H3C0cH3
Q--" - Q
From the 'H-NMR spectrum of the ABCX2-type
[(CDCI,); 6=2.90 (s; 6H, N(CH3)& 3.15 (m; 2H, H'); 5.12
(mc; 1 H, H2); 5.77 (mc; 1 H, H4); 6.57 (mc; 1 H, H3)] it follows that the primary product of the amination (3a) is not
present. An analysis of the apparently simple line shapes
with the automatic program DAVINS141enabled assignment
in favor of the isomer with the dienamine constitution (3b)"I.
Hydrolysis with a phosphate buffer (pH = 2) confirmed the
spectral finding: Whereas (3c) should give exclusively 2-cyclopenten-I-one (5b), a 94:6 mixture of 3-cyclopenten-1-one
( 5 4 and (5b) is formed in 65% yield from (3b)[6.91.It is still
unclear whether the (5b)-part was formed from (3b), (3c), or
by acid-catalyzed isomerization of (3a)c71.
Reaction with pentamethylcyclopentadienyllithium['o~21
instead of (1) affords N,N,1,2,3,4,5-heptamethyl-l,4-cyclo-
Received: August 11, 1980 [Z 625e IE]
German version: Angew. Cbem 92, 1042 (1980)
[ I ] K. Fujrmori, H. Yoshimoto, S. Oae, Tetrahedron Lett. f979, 4397.
121 K. Cann, T. Cole, W. Slegeir, R. Perfit, J. Am. Chem. SOC.100, 3969 (1978).
A. F M. Iqbal, Tetrahedron Lett. 1971, 3385.
[3] R. F. Nystrom, W C. Brown, J. Am. Chem. SOC.70, 3738 (1948); M. L. Burstall, M. S. Gibson, J . Chem. SOC.1958. 3745; H. C. Brown, P. M . Weissman,
J. Am. Chem. SOC 87, 5614 (1965); H. C. Brown, P. M . Weissman, N . M .
Yoon, rbid. 88, 1458 (1966); H. C. Brown, S.Krishnamurfhy, Tetrahedron 3S,
567 (1979).
(41 R. 0. Hutchins, D. W. Lamson, L. Rua, C. Milewski, B. Maryanoff. J. Org.
Chem. 36, 803 (1971); J 0. Morley, Synthesis 1976, 528.
[ 5 ] N. Kambe. K. Kondo, S. Morita, S.Murar. N. Sonoda, Angew. Chem 92, 1041
(1980); Angew. Chem. Int. Ed. Engl. 19. 1009 (1980).
[6] Nitrosobenzene condenses with phenylhydroxylamine under the present
reaction conditions in the absence of H2Te to azoxybenzene in quantitative
yield.
1010
0 Verlag Chemie, CmbH. 6940 Weinheim, 1980
['I Prof. Dr. G. Boche, Dipl.-Chem. M. Bernheim
Institut fur Organische Chemie der Universitat
Karlstrasse 23, D-8000 Miinchen 2 (Germany)
New address: Fachbereich Chemie der Universitat
Hans-Meenvein-Strasse. D-3550 Marburg (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie.
0570-0833/80/1212-10l0
$
O2.S0/0
Angew. Chem. Ins. Ed. Engl. 19 (1980) No. 12
pentadienylamine (4) in 40% yield. In contrast to (3a), (4a)
cannot easily isomerize.
When a solution of (3b) in THF is allowed to react with nbutyllithium in hexane at - 30 "C, the colorless N,N-dimethylaminocyclopentadienyllithium (6) precipitates out in almost quantitative yield ['H-NMR ([D,]-DMSO): S=4.90
(mc; AA'BB' type; 4H, H'-HS); 2.40 (s; 6H, N(CH,),)]. (6)
is the first amino-substituted cyclopentadienide compound;
it can be employed, e. g., for the preparation of metallocenes.
Thus, reaction with FeC1, in THF affords the dark-orange
bis(dimethy1amino)ferrocene (7), m. p. 63-65 "C, in 55%
yield ['H-NMR (CDC1,): 6=2.55 (s; 12H, N(CH,),), 3.95
(mc, AA'BB' type; 8H, HZ-H5, and HZ'-H5')]. To our
knowledge, bis(dimethy1amino) compounds of type (7) were
hitherto unknown. We are currently investigating the chemistry of (3b) and (6).
Procedure
A solution of (2) (4.17 g, 30.0 mmol) in THF (15 ml) was
added at -20°C to a solution of (1)[prepared from cyclopentadiene (2.52 ml, 30 mmol) and n-BuLi (20.1 ml, 30
mmol)] in THF (30 ml). After ca. 10 min the reaction solution turns cloudy. After 30 minutes' stimng at -20°C the
solvent was removed in a high vacuum at - 20 "C and the residue digested with cold pentane. After filtration at - 35 "C
the pentane solution of (3b) was evaporated down in a high
vacuum at -20°C. There remained 1.53 g (47%) of a pale
yellow oil. (3b) is extremely sensitive towards oxygen and
water and decomposes within a few days even in the absence
of air and moisture at - 30 "C. MS (70 eV, direct sample introduction): m/e=109 (loo%, M + ) , 108 (43), 94 (39,
M+-CH,), 58 (57), (CH,)zN==CH;), 44 (74, N(CH2);).
(6): A solution of (3b) (1.35 g, 12.4 mmol) in THF (10 ml)
was treated at -30°C with a solution of n-BuLi (10.0 ml,
15.0 mmol) in hexane, whereupon colorless (6) precipitated
within 2 min. After 1 hours' stirring at -3O"C, (6) was filtered off under N2 at room temperature, washed with pentane and dried in a high vacuum-the product turned lightbrown in color. 1.32 g (93%)of (6) (dec. point 160 "C) was recovered. It immediately decomposes in air, but can be stored
for weeks in a refrigerator in the absence of air.
Chemo- and Diastereoselective Addition
of Alkyl- and Aryltitanium(1v) Compounds
to Aldehydes and Ketones1**]
By Manfred T. Reetz, Ruiner Steinbach, Jiirgen
Westermann, and Roland Peter'']
The addition of Grignard and alkyllithium reagents to carbony1 compounds is one of the important methods for C-C
bond formation. However, it is known that aldehydes and
ketones frequently react equally fast, thereby thwarting chemoselectivity['l, and that diastereoselectivity is limited[''. As
part of our studies concerning the use of alkyl- and aryltitanium(1v) compounds in organic
we have discovered that they (i) add smoothly to aldehydes and ketones, (ii)
react with aldehydes faster than with ketones, and (iii) show
high diastereoselectivity.
The reaction of methyltitanium trichloride (l),dimethyltitanium dichloride (2), methyltitanium triisopropoxide (3),
diphenyltitanium dichloride (4), or phenyltitanium triisopropoxide (5) with carbonyl compounds (6) affords the alcohols
(7) (Table l)'"].
CH3TiCI3
(CH3)2TiCI2
( 1)
(2)
CH3Ti[OCH(CH3)2I3
(3)
Table 1 . Alcohols (7) by addition of titanium reagents (l)-(SJ
and ketones (6) in dichloromethane.
R'
R2
T
["Cl
R'
1
[4] to aldehydes
Yield
WI [bl
Ihl
~
nPr
H
iBu
H
iBu
H
cHex H
cHex H
cHex H
cHex
H
rHex H
-(CHz)sMe
nPent
Received. August 1. 1980 [Z 626 IE]
German version: Angew. Chem. 92, 1043 (1980)
- 40
- 30
0.5
0
0.5
- 40
- 40
0.5
1
0.5
0.5
1
0.3
48
22
- 78
- 10
- 30
22
1
Me
Me
Me
Me
Me
Me
Ph
Ph
Me
Me
> 90
> 90
90
>90
r;95 (78)
zz 95
>90
r;95 (84)
r;95 (82)
0
~
[ I ] To our knowledge only two examples have been previously described in the
( H . W. Thompliterature: N-(3.4-diphenyl-l,3-~yclopentadienyl)pyrrolidine
son, B. S. Huegi, J. Chem. Soc. Perkin Trans. I 1976, 1603) and a N,Nhis(trimethylsilyl)cyclopentadienylamine ( H . Buyer, Dissertation, Universitat Miinchen 1979).
[2]A. Dauison, P. E. Rakita. Inorg. Chem. 9,289 (1970).
[3] Instead of (2), m. p. 33-35 "C, also N.N-dimethyl-0-(diphenylphosphinyl)hydroxylamine, m. p. 128-130 "C, and N,N-dimethyl-0-(diphenoxyphosphory1)hydroxylamine. m. p. 4 5 4 7 "C, may be used. The three reagents were obtained in analogy to the procedure quoted in G. Boche, N.
Moyer. M . Bernheim, K . Wagner, Angew. Chem. 90, 733 (1978); Angew.
Chem. Int. Ed. Engl. 17, 687 (1978).
[4] D. S. Stephenson, G. Binsch, Quantum Chem. Prog. Exch. 11, 378 (1979);J.
Magn. Reson. 37, 395 (1980).
[5]D. S. Stephenson, M. Bernheim. G. Boche, Org. Magn. Reson., in press.
[6]The ratio (So) : (Sb) was determined IR spectroscopically (error + 5%). (Sa):
i=1750cm-'(C-0)[7]; (Sb):i.=1710cm-'(C=O)[8].
171 D L. Whulen, J. E Weimaster, A . M. Ross, R. Radhe, J. Am. Chem. SOC.98,
7319 (1976).
[XI C. J. Pouchert: The Aldrich Library of Infrared Spectra. Aldrich Chemical
Company, Milwaukee, Wisconsin 1970, p. 203.
191 In the preparation of (Sa) according to H. M. Hess, H. C. Brown, J. Org.
Chem. 32.4138 (1968). (So) and (Sb) were formed in the ratio 3:1. Pd-catalyzed synthesis of (Sa): M. Suzuki, Y. Oda, R. Noyori, J. Am. Chem. SOC.
101. 1623 (1979).
(101 R. S. Threlkel, J. E. Bercaw, J . Organomet. Chem. 136, 1 (1977).
Angew. Chem. Int Ed. Engl. 19 (1980) No. 12
[a] In the reaction of (2) or (4) with aldehydes either 1 : 1 or 0.5:1 mixtures can be
used, since both methyl or phenyl groups are transferred. In case of ketones 1 : 1
ratios are necessary. [b] Not optimized the numbers given refer to conversion determined by NMR spectroscopy or gas chromatography. The values in brackets
refer to isolated products.
Complete chemoselectivity is observed in the reaction of
(1)or (3) with a 1:1 mixture of 3-methylbutyraldehyde (6b)
and 2-heptanone (6e). In each case the aldehyde adduct (7b)
is the sole product ( N 95% conversion). Similarly, (5) reacts
with a 1: l mixture of acetaldehyde (8) and acetone (9) to
yield (10)(>90%) as the only addition product. In case of
phenylmagnesium bromide a 1.5 :1 mixture of (10) and
(CH3)2C(OH)C6H5is known to ariseIS1.
['I
Prof. Dr. M. T. Reetz, DiplLChem. R. Steinhach, Dip1:Chem. J. Westermann, R. Peter
Fachbereich Chemie der Universitat
Hans-Meenvein-Strasse, D-3550Marburg (Germany)
1 ' ' ( This work was supported by the Fonds der Chernischen Industrie and the
Deutsche Forschungsgemeinschaft.
0 Verlag Chemie, GmbH, 6940 Weinheim, 1980
OS70-0833/80/lZl2-101I
$02.50/0
1011
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