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Two-Step Sigmatropic Rearrangement versus Aldol Addition of Ammonioimides.

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Reaction of a-diethylaminobutyronitrile with a-chloromethylacrylophenone provides the evidence for dipolar intermediates in [2,3]sigmatropic rearrangements. Heating
the components in acetonitrile in the presence of ethyldiisopropylamine leads to the rearrangement product 13.
The same reaction in the absence of base yields the pyrrolidinium salt 12. Formation of 12 and 13 can, therefore, be
I B
Et
11
.'-...
10
*.
Et
y
clop
12
6, formed from 5 and N,N-dimethylhydrazine 2 does
not react in a [2,3]sigmatropic rearrangement but rather via
an intramolecular aldol addition to form the 4-benzylidenepyrazolinium salt 7. When the reaction with 5a is
performed in ether, apart from 7a, 6a (decomp. 191192 "C) can be separated by fractional crystallization and
be quantitatively converted into 7a (m. p. = 202 "C).
The intermediate appearance of dipolar intermediates
15 in the [2,3]sigmatropic rearrangement of amrnonioimides 13 was established in the course of the reaction of
a-chloromethylacrylophenone 10 with 2. In acetone the
hydroxypyrazolidinium salt 12 is formed, which gives the
methylenepyrazolinium salt 14 (m. p. = 106 "C) on reaction
with tetrafluoroboric acid. When 10 is heated with 2 in
ether, the pyrazolidinium salt 17 (m.p.=164"C) is obtained after work-up. Its formation arises from protonation
of the dipole 15 formed from the ammonioimide 13. The
r
r
A: iPr,NEt, C H K N , A, 3d; B: C H K N , A, 5 d ; C: iPr,NEt, CH2CIZ,25"C,
15h.
explained on the basis that the ylide 11 does not rearrange
directly to 13 but forms the dipole 10, which then, in the
absence of ethyldiisopropylamine, is protonated to 12 by
acid present in the reaction mixture. That 10 is also an intermediate in the [2,3]sigmatropic rearrangement of 11 to
13 is indicated by the fact that ethyldiisopropylamine
completely converts 12 into 13 at room temperature.
Received: January 2, 1980,
in altered form: January 14, 1982 [Z 8b IE]
German version: Angew. Chem. 94 (1982) 202
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982, 398-404
[I] R. W. Hoffmann, Angew. Chem. 91 (1979) 625; Angew. Chem. Int. Ed.
Engl. 18 (1979) 563.
121 R. Gompper, W.-R. Ulrich, Angew. Chem. 88 (1976) 298; Angew. Chem.
Int. Ed. Engl. I5 (1976) 299.
131 R. Gompper, W.-R. Ulrich, Angew. Chem. 88 (1976) 300; Angew. Chem.
In,. Ed. Engl. I5 (1976) 301.
[4] R. Gompper, B. Kohl, Terrahedron Leu. 1980, 907, 917.
14
A : acetone, - I0"C; B: iPr2NEt, EtrO, 25°C; C: Et20, A.
action of 2 on 10 in ether in the presence of ethyldiisopropylamine leads to formation of a 2 :3 mixture of 16 and
17. This finding suggests that 15 is a common intermediate of the formation of 16 and 17. Since 17 does not
react with ethyldiisopropylamine, but is largely decomposed by sodium hydride (thereby only traces of 16 are
formed), the mode of formation of 16 via 15 has not been
completely established.
Two-step Sigmatropic Rearrangement versus
Aldol Addition of Ammonioimides**
By Rudolf Gompper* and Bernhard Kohl
Ammonioimides liberated by the action of base on 1,ldialkyl- I -allylhydrazinium salts rapidly rearrange to 1,ldialkyl-2-allylhydrazines, even at room temperature['.2'. In
I-acyl-2-allylhydrazinium salts, the [2,3]sigmatropic rearrangement is not observed until 130- 150°C".3'. Two-step
[2,3]sigmatropic rearrangement and intramolecular aldol
reactions compete in acceptor substituted ammoniomethanidesl4I. How d o acceptor-substituted ammonioimides behave?
16
Received: January 2, 1980
in altered form: January 14, 1982 [Z 8 c I€]
German version: Angew. Chem. 94 (1982) 203
The complete manuscript of the communication appears in:
Angew. Chem. Suppl. 1982. 405-410
[I] J. E. Baldwin, J. E. Brown, R. W. Cordell, Chem. Commun. 1970. 31.
[21 K.-H. Konig, B. Zeeh, Chem. Eer. 103 (1970) 2052.
131 a) R. F. Smith, R. D. Blondell, R. A. Abgott, K. B. Lipkowitz, J. A. Richmond, K. A. Fountain, J. Org. Chem. 39 (1974) 2036; b) K. Chantrapromma, W.D. Ollis, 1. 0. Sutherland, J. Chem. SOC.Chem. Commun. 1977.
97.
I41 R. Gompper, B. Kohl, Angew. Chem. 94 (1982) 202: Angew. Chem. Int.
Ed. Engl. 21 (1982) No. 3.
Me*N-NH,
%R'
2
Dialkylmagnesium Compounds
from Magnesium, Hydrogen, and 1-Alkenes
5
6
I
a , R', R2 = P h
b , R' = M e , RZ = P h
[*I Prof. Dr. R. Gompper, Dr. B. Kohl
lnstitut fur Organische Chemie der Universitat
Karlstrasse 23, D-8000 Miinchen 2 (Germany)
[**I This work was supported by the Fonds der Chemischen Industrie.
Angew. Chem. Inr. Ed. Engl. 21 (1982) No. 3
By Borislav BogdanoviC*, Manfred Schwickardi, and
Peter Sikorsky
We report a two-step synthesis of dialkylmagnesium
compounds from Mg, H2, and I-alkenes using the recently
described method of preparing MgHJ9'.
[*I Prof. Dr. 8. BogdanoviC, M. Schwickardi, P. Sikorsky
Max-Planck-lnstitut fur Kohlenforschung
Kaiser-Wilhelm-Platz I, D-4330 Miilheim-Ruhr 1 (Germany)
0 Verlag Chemie GmbH, 6940 Weinheim, 1982
0570-0833/82/0303-0199 $02.50/0
199
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two, step, ammonioimides, rearrangements, sigmatropic, aldon, additional, versus
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