вход по аккаунту


Compounds with SiЧTi Linkages.

код для вставкиСкачать
(I) by hydrogen sulfide (in DMSO) with separation of
mercury sulfide. The carbene fragment forms the base peak
(mje = 220) in the mass spectrumt61.
The NMR spectra (measured in [D6]-DMSO as solvent) of
( I ) and (3) prove the structure of (3). The “rneta-coupling”
shown by the salt ( I ) [71 naturally is absent for the complex
(3). The signals of the phenyl protons, and particularly of the
protons on C-4 and C-5, are shifted upfield on conversion of
( I ) into (3).
-0.29 (t)
( J = 1.5)
-. _~-1.95-2.5
1.47 (d)
( J = 1.5)
T = 1.71 (s)
7 =
We have obtained compounds with the hitherto unknown
Si-Ti linkage by treatment of triphenylsilylpotassium with
titanium halides.The stability of the Si-Ti bond is appreciably
increased by neopentane structures, which are particularly
stable in compounds of elements of the fourth main group,
or by substituents that are x-bonded to the titanium.
A characteristic example is the formation of tetrakis(triphenylsi1yl)titanium from TIC4 and ( C ~ H S ) ~ S ~ K :
2.2-2.7 (m)
A mixture of N-(2,2-diethoxyethyl)aniline and phenyl isothiocyanate (molar ratio l:l.l), when kept for 4 days at
room temperature, gave the thiourea derivative (4), m.p.
94OC (yield 88 %), which afforded the thione (5), m.p.
161 O C (yield 66 %), when heated with conc. hydrochloric
acid. Heating (5) with 36 % nitric acid (d = 1.220) gave an
almost quantitative yieId of the nitrate (6) (very hygroscopic),
which was converted into ( I ) , m.p. 169’C (yield 94%), by
dissolution in dilute nitric acid and addition of alcoholic
sodium perchlorate solution.
Complex salt ( 3 ) : 4 g of the salt ( 1 ) and 2 g of mercury(I1)
acetate were shaken in ca. 7.5 ml of DMSO at 8OoC for 10
min. When the solution cooled to room temperature crystals
separated; crystallization was completed by addition of tertbutyl alcohol. When recrystallized from a little DMSO the
complex is obtained in well-formed rectangular plates.
Received: November 20, 1967
[ Z 680 IE]
German version: Angew. Chem. 80, 154 (1968)
[*I Prof. Dr. H.-W. Wanzlick and Dip].-Chem. H.-J. Schonherr
Organisch-Chemisches Institut der Technischen Universitat
1 Berlin, Hardenbergstr. 34 (Germany)
[l] Part XIV of Chemistry of Nucleophilic Carbenes. - Part
XIII: H.-W. Wanzlick and H. Steinmaus, Chem. Ber. 101, 244
121 E. 0. Fischer and A . Maasbol, Chem. Ber. 100,2445 (1967),
where previous literature is cited.
[3] U.SchoNkopf and F. Gerhart, Angew. Chem. 79, 819 (1967);
Angew. Chem. internat. Edit. 6, 805 (1967), where previous
literature is cited.
[3a] U.Schoflkopf and F. Gerhart, Angew. Chem. 79,990 (1967);
Angew. Chem. internat. Edit. 6, 970 (1967).
[4] Cf. W. Kirmse: Carbene Chemistry. Academic Press, New
York, London 1964.
[S] Formulation of the complex by analogy with the symbolism
used for other carbene-metal complexes [2,31.
[6] We thank Dr. D. Schumann for the measurement of the
spectrum. Apparatus: AEI MS 9, 70 eV, 350 “C.
[7] Cf. G. S. Reddy, R. T . Hobgood, and J . H . Goldstein, J. Amer.
chem. SOC.84,336 (1962).
By E. Hengge and H. Zimmermann[*I
The salt (1) was prepared as follows:
Compounds with Si -Ti Linkages
Ethereal solutions of (C6H5)3SiK and Tic14 are simultaneously added dropwise to ether at 0°C with stirring. Stirring
is continued overnight, then the mixture is poured on ice plus
2 N HCI; the water and ether are then separated off and the
precipitate is washed with methanoljwater and ether and
recrystallized from xylene (yield 44 %).
Tetrakis(triphenylsily1)titanium is a pale yellow substance
that melts a t 395-40O0C with decomposition. It is very
sparingly soluble in xylene, toluene, or benzene, and insoluble in all other solvents. Its particular stability may
depend above all o n the strong shielding of the phenyl groups
in the neopentane structure, and on the high symmetry.
Aqueous alkali decomposes the compound slowly, causing
evolution of hydrogen:
The amount of hydrogen evolved corresponds t o theory
(Si: H2 = 1:l).
The IR spectrum shows, besides the usual CH, phenyl, and
Si-phenyl bands, a new band at 900-940 cm-1. This vibration
may be associated with the neopentane skeleton since similar
bands appear for similar compounds such as [(CH&Si]4Si.
(C6HS)3SiK reacts also with CI2Ti(x-CsH& forming a Si-Ti
+ 2 KSi(C6H&
+ (~-CSHS)~T~[S~(C~HS)~]Z
The reaction is carried out in diglyme (diethylene glycol dimethyl ether) with ice cooling. The resulting reddish-brown
solution is evaporated and the resulting residue is extracted
with chloroform. On addition of pentane t o the extract,
yellow bis(triphenylsilyl)di(x-cyclopentadienyl)titanium
precipitated and is purified by sublimation at 280OC (yield
35 %).
Received: November 30, 1967
[ Z 682 IE]
German version: Angew. Chem. 80, 153 (1968)
[*] Prof. Dr. E. Hengge and Dip1.-Ing. H. Zimmermann
Institut fur Anorganische Chemie
der Technischen Hochschule
A-8010 Graz, Rechbauerstr. 12 (Austria)
Synthesis of Methyl 4,6-0-Benzylidene-2,3(2’-hydroxyethylidene)-ol-D-mannopyranoside,
a Cyclopropane Sugar
By W. Meyer zu Reckendorf and U. Kamprath-Scholta~*l
PO-Activated olefination, as described by Horner [I], has
seldom been used for the preparation of sugars with a
branched carbon skeleton. Its applicst ion t o the preparation
of cyclopropane derivatives from epoxides of the sugar series
has not previously been described.
We treated the epoxide ( I ) 121with ethyl diethoxyphosphorylacetate [3J, (CzH50)2PO-CH2COOC2H5, and N a H in diAngew. Chem. internat. Edit, VoI. 7 (1968) J No. 2
Без категории
Размер файла
128 Кб
linkage, siчti, compounds
Пожаловаться на содержимое документа