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Bis-Silylated Carboxamides.

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azulenoid system resonance into the energetically more favorable benzenoid system (6). Compound (6) crystallizes in
golden-yellow needles of m.p. 116 to 117OC; its ultraviolet
spectrum has a strong fine structure: Amax 231 mp (log E 4.55); 235 (4.55); 280(3.91); 291 (3.80); 312(3.71); 325 (3.69);
340 (3.59); and 406 (3.20).
Compound (6) absorbs 3 moles of H2 to form the indane
derivative (7). With trityl perchlorate, (6) gives the stable
orange carbonium salt (a), a p . 236 to 238OC with decomposition. With methyl-lithium, (6) forms a green compound (9), which is sensitive to hydrolysis. Compound (9)
is an example of a cyclic conjugated 14 lrelectron system
with the general structure (10).
Attempts to extend this ring expansion reaction with azides
to other aromatic systems are in progress.
1.2 392/242I€]
By Prof. Dr. 0. Wcstphal and Dip1.-Chem. G. Feix
[I] K. Hqfner and H. Kuiser, Liebip Ann. Chem. 618,140 (1958).
[2] A. M . Patterson, L.. T. Cupell, and D. F. Walker: The Ring
Index. 2nd Edition, American Chemical Society, Washington,
D.C.,1960, p. 409.
[3] K. Hafner. H . Pelster, and J. Schneider, Liebigs Ann. Chem.
650,62 (1961).
[4] K. Hajner et al.. Liebigs Ann. Chem. 650, 80 (1961); 624,37
(I 959).
Chemisches lnstitut der Universitilt Freiburg/Breisgau
Rcceived, November 19th. 1962
By Prof. Dr. K. Hafner and Dr. C. Kbnig
lnstitut fur Organische Chemie
der Universitiit Munchen (Germany)
By irradiating a solution of ethyl azidocarbonate in benzene
with ultraviolet light, we obtained N-ethoxycarbonylazepine
(2) in ca. 70 "/,yield as a stable yellow oil, b.p. 130 OC/20 mm
(A,nax = 208 my (log e = 4.44) and , ,A
= 330 III@ (log E =
2.72) in n-hexane).
Rcccivcd. November 20th. 1962 [Z3961243 I€]
.. -.
[I] W.Lwowski and Th. W. Muttingly, Tetrahedron Letters 1962,
[21 K. Dimroih and H. Freyschlug, Chem. Ber. 89,2602 (1956);
90, 1628 (1957); R. Huisgen and M . Appel, ibid. 91, 12 (1958);
R. Huisgen et al., ibid. 93. 392 (1960); Liebigs Ann. Chem. 630,
128 (1960, erc.
131 L. Ruzlcka et al., Helv. chim. Acta 32,544 (1949).
Synthesis of Dehydroquinolizinium Systems
It has been shown [I] thal 1.2-diketones can be condensed
readily with N-methylene-a-picoliniumsalts to give dehydroquinolizinium derivatives. Here the first component supplies
the two ketonic groups necessary for cyclization, and the
second supplies the two activated methylene groups. We have
now gone over to using two reactants, each of which contains
both a ketonic group and an activated methylene group, so
that monoketonic compounds derived from N-methylenepyridinium-2-aldehyde can be used for the synthesis of dehydroquinolizinium systems.
The 1,3-ketol (I) formed from pyridine-2-aldehyde and deoxybenzoin W B S esterified and converted into the quaternary
ammonium salt (2) using bromoacetophenone; the salt (2)
was then cyclized using dibutylamine in boiling acetone to
give 2,3-diphenyl-dehydroquinoliziniumbromide (3). In this
way, as also in the synthesis mentioned above [I], the activating residue R is split olT as benzoic acid. The yields of
the individual reaction stages are between 65 and 80 %.
This new ring expansion reaction resembles the photolytic
reaction of benzene with diazomethane to yield cycloheptatriene. Here, however, instead of the methylene group, the
ethoxycarbonylazene group [II reacts with the benzene,
probably to give first the azanorcaradiene derivative ( I ) ,
which rearranges a t once to its isomeric azepine (2).
Compound (2) is the first monocyclic azepine derivative to
have been prepared [2]. Catalytic hydrogenation of (2) with
Pd/Hz a t 20 OC affords N-ethoxycarbonyl hexamethylene
imine (b.p. 118--120"C/20 mm; nil = 1.4635), which we
also prepared from hexamethylene imine 131 and ethyl
chloroformate. The two products proved to be identical,
judging from their infrared and nuclear magnetic resonance
spectra. The NMR-spectrum of (2) shows a multiplet for the
6 ring protons at 4-4.7 T, in addition to the characteristic
signals for the protons of the ethyl group (quartet at 5.8 7,
triplet at 8.7 7).
The stability of the 8 r-electron system in (2) appears to be
due at least in part to the claim on the free electron pair on
the nitrogen made by mesonierism of the urethane system. In
the presence of protic acids, (2) resinifies rapidly at 2OoC.
Judging from its melting point (284-285 "C), mixed meltingpoint, and infrared spectrum, compound (3) is identical with
the compound obtained from benzil and N-carbethoxy-apicolinium bromide [2].
Rmivcd, November 191h, 1962 I2 3981222 1El
[I] 0. wesrphul, K. Junn, and W. Heffe, Arch. Pharmac. 294,31
(I96 I).
121 K. Junn, Ph. D. thesis, Universittit Freiburg/Breisgau. 1958.
Bis-Silylated CarboxamidBy Prof. Dr. L. Birkofer, Dr. A. Ritter
and Dipl.-Chem. W. Giessler [I]
lnstitut filr Organische Chemie
der Universitlt Kbln (Germany)
Silylation of 1 mole of acetamide with 1 1nOl6 of trimethylchlorosilane in the presence of triethylamine gives N-trirnethylsilylacetamide[2]. On the other hand, reaction of a
Angew. Chem. ititiwlut. Edit. [ Vol. 2 (1963)
1No. 2
fairly large excess of trimethylchlorosilane with 1 mole of
acetamide under the same conditions produced in good yield
u carboxamide which is bis-silylated at the amide group, viz.
the hitherto unknown bis(trimethylsilyl)acetamide (I).
This is a colorless liquid (b.p. 67.SoC/30 mm) and is very
sensitive towards hydrolysis. It proved possible in the same
way t o transform acrylamide into bis(trimethylsilyl)acrylamide (2), a colorless liquid of b.p. 73.SoC/22 mm. Investigations are in progress to decide between the two
structures possible in each caw.
dSi-,andlor R . C-N-
” .
Miss A. Sieburg carried out the invcstigations on the rhenium
Refcived, December Sth, 1962 [Z 404/228 1E)
[*I At present situated in the Max-I’lanck-Institui fur Chemie
(Otto-Hahn-lnstitut)in Mainz, Gerniany.
[I] E. Weise. 2. anorg. allg. Chem. 283,377 (1956).
121 J. L. Hoardand W . B. Vincent. 3. Amer. chem. SOC.61,2849
( 1939).
[3] R. D. Peacock, Chem. and Ind. IVSS, 1453.
(41 H.Bode and W.Wen& 2.anorg. iillg. Chem. 26Y. 165 (1952).
[5] Density determination: cf. K. Srhworhau, Z. Naturforsch. 170
630 (1 962).
(1) R
Complexes of MoIybdenum(II1) with 1,3-Diketones
(2) R == H2C ICH
By DipLChem. K. Christ and Prof. Dr.
Limburg and Post [31 thought that they had prepared (I) by a
reaction between ketene and hexamethyldisilazdne,
[(H3C)3Si-NH-Si(CH3)3]. The very high boiling point
(61.5°C/0.15 rnm) differs from that of our product, and the
analytical data do not correspond to the required values; this
proves that these authors had not obtained the substance
Received, December 4th. 1962
[Z4051229 I€]
lnstitul fur Physikalische Chemie
der Universitiit FrankfurtlMain (Germany) [*I
We have prepared the following co-ordination compounds
of trivalent molybdenum:
b -c‘
“!!I I
[ I ] 17th Communication on organosilicon compounds; 16th
Communication: L. Birkofer, A. Rirrer. and H. Dickopp, Chem.
Ber., in the press.
12) L. Birkofer, A. Ritter. and H. Dickopp, Chem. Ber., in the
131 W. W.Limburg and H.W. Post, Rec. Trav. chim. Pays-Bas
81, 430 (1962).
Preparation, Properties and Crystal Structure of
Potassium Hexafluorotechnetate(1V)
By Dr. K. Schwochdu and Prof. Dr. W.Herr
Arbeitsgruppe Jnstitut fur Radiochemie” der
Kernforschungsanlage Jiilich (Germany) and lnstitut fiir
Kernchemie der Universitiit K6ln (Germany) [*]
In analogy with the preparation of the corresponding
rhenium compound [I], we obtained K I (99TCF6) on melting
KzvcBr6) with K HF2. Potassium fluorotechnetate was
isolated in a pure state and in 60-70 % yield by recrystallization from water as pale pink, hexagonal platelets. The
solubility of the salt at 25 O C was 1.5 g in 100 g of water.
The absorption spectra of the (T‘CF6)2- and (ReF6)2- ions
are extensively similar in the visible, ultraviolet, and infrared
regions, as was to be expected. While the other hexahaIogen
complexes of tetravalent technetium and rhenium do not
absorb in the infrared spectral region of 4OOO-400 cm-1, an
intensive band was found for K2(TcF6) at 574 cm-1 (17.4
(z), and one for Kz(ReF6) at 550 cm-1 (18.2 (z); these are to
be assigned to the Tc-F and Re-F oscillations respectively.
The resistance of the fluorotechnetate to hydrolytic decomposition is particularly noteworthy. Chloro-, bromo-,
and iodotechnetate (IV) all undergo hydrolysis even in
weakly acid solution but (TcF~)~only in hot conc. aqueous
According to X-ray structura1 investigations, K2ncF6)
crystallizes a t room temperature in the trigonal Kz(GeF6)
type [2] with lattice constants a = 5.807 j, 0.002 A and
c = 4.645 f 0.002 A, and is isomorphous with Kz(ReF6) [1,3]
and a modification of Kz(MnF6) [4] at low temperature.
The density of potassium fluorotechnetate was measured as
p = 3.58 f 0.01 dcm3 [4]. It follows from this and from the
crystal structure that the unit cell contains one formula
Angew. Chem. internut. Edit.
VoI. 2 (1963) I No. 2
H.L. Schliifer
The following diketones were uscd: (I) acetylacetone [I],
(2) trifliioroacetylacetone,(3) bcnzoylacetone, (4) dibenzoylmethane, and (5) thenoyltrifluoroacetone.
The ketones (I) and ( 2 ) were treated with K3[MoIuClb] in
aqueous methanol at room tempcrature, the acid formed
being buffered with ammonium acetate. The compounds
precipitate after fairly prolonged standing. Molybdenum(lll)tris-acetylacetonate was recrystallized from a mixture of nhexane and tetrahydrofuran (2:l), while n-hexane was used
for molybdenum(l1l)-tris-trifluoroacctylacetonate.
Solubility difficulties arise with ketones (3), (4), and (5) but
can be circumvented by using a tcrnary mixture of dioxanl
methanol/water as rextion medium and ( N H & [ M o ” ~ ~ s (HzO)] as starting material. The required compounds were
then obtained by fairly prolonged and vigorous stirring at
room temperature followed by evaporation of the solvent in
vacuo. The products are deep rcd-brown to black. They
dissolve in organic solvents such as benzene, tetrahydrofuran,
CC14, and partially in n-hexane to give deep red-black
solutions. Scveral of the compounds become hot spontaneously in air. As the size of the organic ligand increases, the
tendency to give tarry products during this process grows.
All manipulations must be carried out under highly purified
nitrogen, and it is essential to remove carefully any traces
of dissolved oxygen from the solvents.
The preparation of the compounds mentioned and the
results of investigations of their optical and magnetic properties will be published in the near future.
Received, Decemher 7th. 1962 [Z4101236 IEl
[I] Molybdenum(llI)-trisacetylacetonate has also been prepared
by M . L. Larson and F. W. Moore, J. inorg. Chem. 1.856 (1962).
Barium Halogenonitrides
By Prof. Dr. P. Ehrlich, Dr. E. Koch
and DipLChem. V. Ullrich
Jnstitut f i r Anorganischc und Analytische Chemie
der Univcrsit‘it GieBen (Germany)
Continuing an earlier investigation [I] of the chloronitrides
of alkaline earth metals, in which the existence of the compounds CazNCl and BazNCl was verified, the systems
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carboxamides, silylated, bis
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