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Formation of Ylides on Thermal Decomposition of P-(-Alkoxycarbonylalkyl)triphenylphosphonium Salts.

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tested this reaction for its general applicability and have
found that the azines ( l a ) to (re) can be converted smoothly
and quantitatively into the carbonyl compounds (2) by
stirring them at room temperature with a n excess of manganese dioxide in benzene or carbon tetrachloride. We have
also studied the hydrazones (4.) to (4d). Whereas azines
are cleaved relatively slowly (reaction time 2 h to 14 days),
hydrazones afford the carbonyl compounds (2) more easily
(within a few hours), and equally quantitatively, under the
same conditions. In the latter case diazo-compounds (3) are
formed as intermediates, which can be detected spectroscopically. 9-Fluorenone hydrazone is converted analogously
into 9-fluorenone by way of 9-diazofluorene.
The carbonyl compounds (2) are formed directly from the
diazo compounds (3) by exchange of nitrogen for oxygen;
thus diphenyldiazomethane gives benzophenone quantitatively. The fact that only acetone arises from acetone
We assume that the rearrangements involve the two metalated
ethers (la) and ( I b ) . Whereas the 1,2-shift may occur by a
fission-recombination mechanism 131, the course of the orthorearrangement is unknown.
I
1
(IbJ
Hydrolysis
Hydrolysis
(3)
(2)
9-Lithio-9-fluorenyl 2-butynyl ether (4), when similarly
( 5 ) 141.
treated, yields only 9-(l-methylallenyl)-9-fluorenol
Received: September 29th. 1965 [Z 70/899 IE]
German version: Angew. Chem. 77, 1012 (1965)
hydrazone shows that alcohols cannot be intermediates; if
they were, isopropyl alcohol would be obtained since it is
stable under the reaction conditions.
Benzil dihydrazone gives tolane quantitatively within 30 min,
but no benzil. Moreover, n o benzil is obtained from benzil
monohydrazone since a-diazo ketones (e.g. diazoacetophenone) - and also diazoacetic ester - d o not exchange
their nitrogen for oxygen. This explains why diazo ketones
can be isolated o n oxidation of monohydrazones of a$dioxo compounds with manganese dioxide [2].
Carboxyhydrazides react with active manganese dioxide with
evolution of nitrogen, giving carboxylic acids in quantitative
yields.
Received: September 15th. 1965 [Z 62/888 IE]
German version: Angew. Chem. 77, 967 (1965)
[I] G. Maier, Chem. Ber. 98, 2438 (1965).
[2] S. Hauptmann, M . Kluge, K.-D. Seidig, and H. Wifde, Angew.
Chem. 77,678 (1965); Angew. Chern. internat. Edit. 4,688 (1965).
Ortho-Rearrangement of Metalated
Butynyl Benzyl Ether
By Prof. Dr. U. Schollkopf and Dr. M. Rizk
[I] Cf. C . Wittig, Angew. Chem. 63, I5 (1951); Experientia 14,
389 (1958); H . E. Zimmermann in P. DeMayo: Molecular
Rearrangements. Interscience, New York/London 1963, Vol. I,
p. 372.
[2] Proof of structures by synthesis.
[3] U.Schiiffkopf et al., Liebigs Ann. Chem. 642, 1 (1961); 654,
21 (1962); 663, 22 (1963); H. P. T. Lansbury and V . A . Pattison,
J. org. Chemistry 27, 1933 (1962); J. Amer. chem. SOC. 84, 4295
(1962).
[4] In cooperation with Dip1.-Chem. K. FeIfenberger.
Formation of Ylides on Thermal Decomposition of
P-(a-Alkoxycarbonylaky1)triphenylphosphonium
Salts
By Prof. Dr. H. J. Bestmann, Dr. H. Hartung, and I. Pils
Institut fur Organische Chemie der Technischen Hochschule
Miinchen und der Universitat Erlangen-Niimberg (Germany)
P-(A1koxycarbonylmethyl)triphenylphosphonium salts ( I )
decompose when heated above the melting point, yielding
a methyltriphenylphosphonium salt (2), a n olefin (3), and
carbon dioxide[ll.
0
[(C&H5)3P-CH2 - COz - CH2- CHz - R]X@
Organisch-Chemisches Institut
der Universitat Gottingen (Germany)
Two types of rearrangement are known 111 to compete in the
base-induced rearrangement of trialkylbenzylammonium
salts, namely, the Stevens rearrangement (I ,2-shift) and the
Sommelet rearrangement (ortho-rearrangement) in which a n
alkyl group migrates to the ortho-position of the benzyl group.
Hitherto only the 1,2-shift has been known for alkyl benzyl
ethers, for which it is known as the Wittig rearrangement 111.
We have now found that a n isomerization corresponding to
the Sommelet rearrangement is also possible for one of these
ethers. For instance, if 2-butynyl lithiobenzyl ether ( I ) ,
prepared from benzyl 2-butynyl ether and butyl-lithium in
tetrahydrofuran at -3OoC, is kept for 14 h in tetrahydrofuran at -6OOC and the mixture is then hydrolysed with
CH,OH/H20 at 60 "C, I-(o-methylphenyl)-2-butyn-l-ol(3)
can be isolated in 46 % yield as a result of a n ortho-rearrangement; 1-phenyl-3-pentyn-1-01 (2) is formed also, in 18 %
yield, by a Wittig rearrangement 121.
Angew. Chem. internat. Edit.
1 Vol. 4 (1965) 1 No. I I
0
[(CsH5)3P-CH31XG + C o z
f 1)
(2)
+
CH2=CH-R
(3)
We assume that this reaction begins with the formation of
a n alkylidenephosphorane (4) and a carbonium ion (5), from
which the products (2) and (3) are at once formed by
@-elimination.
(1)
-co*
A
CHz=P(C&5)3
(41
f
@ C H Z - C H ~ - R+
x@
(5)
i.9
+ OP(C&)3
161
957
The intermediate occurrence of the phosphorane (4) becomes
obvious if the decomposition is carried out in boiling cyclohexanone; on subsequent distillation methylenecyclohexanone (6) is obtained in 1 % yield.
On thermal decomposition of P-(1-acyl-1-ethoxycarbonylethy1)triphenylphosphonium chlorides (7) the residues consist of the stable ylides (8) (R = C6H5, m.p. 172OC, yield
98 %; R = C6H5-CH=CH, m.p. 200 'C, yield 82 %). The
compounds (8) are weak bases. They attack the carbanions
(5) (R = H ) only slowly, and these ions react preferentially
with the chloride ions; one thus obtains ethyl chloride which
distils off and can be isolated in a cooled receiver.
[
p
R-
3
-?-COzCzH5
g(CBH5)S
]
CH3
C1°
A R-G-k + COz + ClCzH5
0 P(Cd&),
diphenylphosphine (14) that can be converted into the oxide
(15) by oxidation. Nuclear magnetic resonance spectra of
(13), (14), and (15) are in accord with the structures assigned.
Received: May 26th, 1965
[Z 72/900IE]
German version: Angew. Chem. 77, 1011 (1965)
Publication delayed until now at the authors' request
[ l ] A . Michaelis and H . v . Gimborn, Ber. dtsch. chem. Ges. 27,
272 (1894); D . B. Denney, C. J . Rossi and J. J. Vill, J. Amer.
chem. SOC.83, 3336 (1961); J. org. Chemistry 29, 1003 (1964).
121 H . J. Bestmann, H. Haberiein and I. Pils, Tetrahedron 20,
2079 (1964).
[3] S. Fliszar, R. F. Hudson, and G . Salvadori, Helv. chim. Acta
46, 1580 (1963).
141 For the electrolysis of phosphonium salts, see L. Horner and
A . Mentrup, Liebigs Ann. Chem. 646, 65 (1961).
(8)
( 7)
Heating P-[1,2-di(methoxycarbonyl)ethyl]triphenylphosphonium bromide (9) at 15OoC affords methyl acrylate (75 %)
and triphenylphosphine (70%). We assume that an ylide
(10) is formed as intermediate in this case also and then
decomposes into the products named owing to a n intramolecular Hofmann degradation 121. During the decomposition methyl bromide distils alongside the ester and can
be condensed in a cooled receiver.
COz + CH3Br
?
+ 5-CHz-COzCH3
p ( c 6H5)3
( 10)
1
P(CeH5)3 + C H ~ = C H - C O Z C H ~
Carbon dioxide is evolved when the phosphonium salt (11)
obtained [31 from a-bromo-y-butyrolactone and triphenylphosphineis heated at 18O-19O0C. The carbonium ion ( I Z ) ,
assumed to be an intermediate product, passes into cyclopropyltriphenylphosphonium bromide (13) by C-alkylation
of the ylide that is present in the same molecule; this salt
(13), which is not otherwise accessible, remains quantitatively
as residue in the reaction vessel.
A New Ring System Containing Boron
By Prof. Dr. F. Umland and Dr. B. K. Poddar
Anorganisch-Chemisches Institut der Universitat Munster
and Institut fur Anorganische Chemie
der Technischen Hochschule Hannover (Germany)
In chelates and chelating agents containing short intramolecular hydrogen bonds (2.4-2.6 A), boron can be introduced
in place of the proton [ 1,2]. In N-salicylideneanthranilicacid
( I ) there are two possibilities for hydrogen bonds to the same N
atom. Thus it should be possible to replace two hydrogen
atoms by a single boron atom. In fact, when compound ( I )
reacts with diphenylborinic acid, one phenyl residue is
removed from the latter with smooth formation of B-phenyl(N-salicy1ideneanthranilato)-O,O,N)-boron (2). Reaction
with boric acid affords p-oxobis- (N- salicylideneanthranilato)-O,O,N-boron (3). The structures of the products were
proved by analysis and infrared spectra. Compounds (2) and
(3) have considerable stability towards acids and alkalis.
It is surprising that attempts to prepare chelates of compound
( 1 ) with the bivalent metals Cu, Zn, and Cd led to chelates
of anthranilic acid with fission of the azomethine linking.
Preparative methods
One mole each of compound ( I ) and a compound containing
a B-phenyl group (phenylboronicor diphenylborinicanhydride,
Flavognost@,Kalignost@)for preparation of (2), or boric acid
for preparation of (3), are refluxed for about 15 min with
about one liter of glacial acetic acid. After cooling, compounds (2) or ( 3 ) slowly crystallize. The products are washed
first with glacial acetic acid and then with warm water and
alcohol and are dried in a vacuum desiccator over sulfuric
acid. They are yellow and fluoresce yellowish-green or green
in ultraviolet light.
I;"'
Received: September 9th, 1965 [Z 64/890 IEI
German version: Angew. Chem. 77, 1012 (1965)
.. -
Treating the bromide (13) with aqueous sodium hydroxide
affords cyclopropyldiphenylphosphine oxide (IS), and
electrolysis of the aqueous solution (41 affords cyclopropyl-
958
.. . .
[ I ] F. Urnlandand D.Thierig, Z. analyt. Chem. 197, 151 (1963).
121 F. Umland and C . Schleyerbach, Angew. Chem. 77, 426
(1965); Angew. Chem. internat. Edit. 4, 432 (1965).
Angew. Chem. infernai. Edii.1 Vol. 4 (1965) No.I 1
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salt, decompositions, thermal, formation, triphenylphosphonium, alkoxycarbonylalkyl, ylide
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