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Dialkylmagnesium Compounds from Magnesium Hydrogen and 1-Alkenes.

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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 $02.50/0
199
Mg
-
+ H2
L.N
+
/THF
c.u / T H k
MgHZ 2CH,=CHR
R = H, alkyl
v
MgHz
(3)
Mg(CHZCH2R)l
(4)
Isoquinolines and Naphthalenes from p-Polyketones:
Model Reactions for an Extraordinary Alkaloid
Biosynthesis**
By Gerhard Bringrnann*
The catalysts for the preparation of MgH2 (Mg-anthracene-CrCI, or -TiC1,)[9’are also suitable for the addition of
MgH, to ethylene or propene to give, respectively, diethylor dipropylmagnesium.
Zirconium tetrahalides and magnesium hydride (MgH,ZrX,; X = C1, Br, I) are considerably more active catalysts
for the addition step (4). By this means MgH2 can also be
added smoothly to higher I-alkenes. The following modification to the procedure has proved useful: Mg is initially
hydrogenated to the highly reactive MgHz in the presence
of the chromium catalyst at room temperature; addition of
1 mol% zirconium tetrahalide at 70-90°C in the presence
of 1 -alkenes leads to dialkylmagnesium compounds. The
“hydromagnesation” of higher boiling I-alkenes (b.p.
>70°C) can be carried out at atmospheric pressure by refluxing (Fig. 1)[12]. The best results are obtained using catalysts containing ZrX,, particularly Z1-14 (80-85% conversion after 1-2 h).
Until now it has been assumed that in nature isoquinoline alkaloids are formed, without exception, via the Mannich reaction of phenylethylamines with aldehydes or a0x0 acids. Because of its unusual substitution pattern, ancistrocladeine 1, obtained from the spasmolytically active
H,CO
OCH,
3HJ , -q0H
H,CO
CH,
tropical liana“] Ancistrocladus heyneanus, appears to necessitate a different biosynthetic route. We report the synthetic approach to both molecular moieties (9 and 11) of 1
by successive cyclization of b-polyketones, which can be
viewed as a model reaction for the formation of a n isoquinoline alkaloid from acetate units.
m$
2
R’, R2 =
3 R’ = H, RZ = OCH,
N
I
0
I
.-
b,/65%
-I
I
0
10
5
t
lhl
OH f?
Fig. I. Course of the MgHl addition to I-octene with time using different catalysts in boiling media; MgHz prepared in siru at 25°C in presence
of the Cr catalyst. MgH?: I-octene:cat. = 100:230: I : [cat.]=O.O12mol/L:
(-A-),
ZrL: (-0-), ZrCI,: (-D-),
ZrBr4: (-V-),
TiCI4; ( - 0 - ) ,
-), without catalyst.
HfCI,: (-O-), (C5H,),TiCI2: (-
Reaction of the dialkylmagnesium compounds with
electrophiles indicates that the catalytic “hydromagnesation” of I-alkenes proceeds practically regiospecifically
(>99.7%) in the sense of M-C1 addition. Addition of
MgH2 to 1,l- and 1,2-dialkylalkenes is, in comparison,
very slow.
The dialkylmagnesium compounds can be isolated pure
and catalyst-free. They can be used in situ in syntheses instead of Grignard reagents. For example, tetrabutyltin
(83%) could be isolated from a solution containing catalyst, tin tetrachloride, and dibutylmagnesium, or nonanoic
acid (78%) could be obtained from dioctylmagnesium with
C 0 2 / H 2 0 . Trioctylphosphane (84%) and tetraoctyltin
(95%) could be prepared, respectively, from pure isolated
dioctylmagnesium and phosphorus trichloride and tin
tetrachloride, respectively.
Received: September I I , 1981 [Z 1 1 IE]
German version: Angew. Chem. 94 (1982) 206
The complete manuscript of this communication appears in:
Angew. Chem. SuppI. 1982, 457-460
191 B. Bogdanovii S. Liao, M. Schwickardi, P. Sikorsky, B. Spliethoff, Angew. Chem. 92 (1980) 845: Angew. Chem. Inr. Ed. Engl. 19 (1980) 818.
[I21 4.0 mL of the suspension was removed at specific intervals, centrifuged,
and the Mg content of the clear solution determined acidometrically.
200
0 Verlag Chemie GmbH. 6940 Weinheim, 1982
H O,
O
m
OH I
H,CO
I
8 , R = CHzCHzOH
9 , R = H
10, R = H
11, R = CH,
Scheme I. a) 0,. - 78 “ C (see Procedure). b) S O 2 , Et20, 25 “C. c) Me2SOJ,
K2CO?,acetone, 25°C. d) Conc. NH,, CH,OH, 25°C. e) KH, tetrahydrofuran, 25°C. f) KOH, CH,OH, 25°C. g) Me2S04, 10% aqueous KOH, CHIOH,
12 h reflux.
The synthesis of 9 and 11 is shown in Scheme 1. The ketalized pentaketone 4 [‘H-NMR (CDCl3): 6 = 5.42, s, olefin. C H of the enol form] is liberated as an oil from 2 by
mild ozonolysis in the absence of oxygen. This method of
who did not succeed
obtaining 4 stems from Birch el
in cyclizing 4 to afford phenols. We found that the ring
closure of 4 to 6 (m.p.= 139°C) can, nevertheless, be realized smoothly by filtering the ozonolysis product through a
[*] Dr. G. Bringmann
Organisch-chemisches lnstitut der Universitst
Orleans-Ring 23, D-4400 Miinster (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
0570-0833/82/0303-0200 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 21 (1982) No. 3
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