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As12tBu8Чa Tricyclo[6.4.0

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Since cyanohydrins are useful synthetic building blocks,
the importance of a general stereoselective synthesis is obvious. The addition of HCN to L-arabinose described by
Kiliani and Fischer about 100 years ago was one of the first
examples of 1,2-asymmetric induction in organic chemistry.I'"l
1 is formed on dehalogenation of a mixture of tert-butyl(dich1oro)arsane and arsenic(rr1) chloride with magnesium in boiling tetrahydrofuran (THF).
+ 4AsCll + 14Mg
+ 14MgC12
Received: July 11, 1985 [Z 1381 IE]
German version: Angew. Chem. 97 (1985) 989
Review: M. T. Reetz, Angew. Chem. 96 (1984) 542; Angew. Chem. I n t .
Ed. Engl. 23 (1984) 556.
Synthesized by cyanation of the corresponding acyl chloride with
Me,SiCN. Review of the synthesis and reactions of acyl cyanides: S .
Hiinig, R. Schaller, Anyew Chem. 94 (1982) 1: Angew. Chem. lnt. Ed.
Engl. 27 (1982) 36. Normal acyl cyanides undergo TiCL-mediated additions with allylsilanes and silyl enol ethers: G. A. Kraus, M. Shimagaki,
Terrahedron Lett. 22 (1981) 1171.
For work-up, the cold reaction mixture was added to water under acidic
conditions. The chromatographic purification of 314 (silica gel/petroleum ether 40-6Wether (1 :3) gave 69% analytically pure product. The
assignment is based on analogy to the TiC1,-controlled allylsilane-addition 10 aldehydes [l] and was supported by conversion of 314 into the
acetonides, whose I3C-NMR spectra confirmed the assignment. The assumption of chelation-control [ I ] in the other reactions seems justified
on grounds of plausibility; X-ray structure analyses are presently under
Basic conditions should he avoided since the cyanohydrins decompose
or undergo configurational equilibration. 6 slowly loses HCN on standing (22°C).
M . T. Reetz, K. Kesseler, A. Jung, Tetrahedron 40 (1984) 4327.
17 adds to aldehydes in the presence of Zn12; see, e.g., S. Hiinig, M.
Oller, Chem. Ber. 174 (1981) 959, and references cited therein; review of
the chemistry of 1 7 : W. C. Groutas, D. trlker, Synthesis 1980, 861.
J . R. Hwu, J. G. Lazar, P. F. Corless, Synthesis 1984, 1020; and references cited therein.
2 1 is a preparatively useful alternative to glyceraldehyde acetonide [I]:
K . Kesseler, Disserratron, Universitat Marburg 1985; M. T. Reetz, K.
Kesaeler, J . Org. Chem., in press.
I Acidic work-uo with H,O
- 131
. . (,2 5 / 2 6 were isolated in 76% vield).
[lo] H Kiliani, Ber. Dtsch. Chem. Ges. 19 (1886) 3029; E. Fischer, ibid. 23
(1890) 2611.
By Marianne Baudler* and Stefan Wietfeldt-Haltenhoff
Dedicated to Professor Max Schmidt on the occasion of
his 60th birthday
In contrast to the corresponding phosphanes,"] polycyclic arsanes are still hardly known. Only in the past few
years could the nortricyclene-analogue A s ~ ( S ~ M ~ , ) ,as
well as the tert-butyiarsanes A~,tBu,'~land A s ~ / B uana~'~~
logous to pentalane and bicyclobutane, respectively, be
synthesized as the first representatives['I. According to
more recent findings,[6' arsenic, like phosphorus, is capable
of forming polycyclic molecular structures. We have now
succeeded in synthesizing octa-tert-butyldodecaarsane 1,
the first compound with twelve arsenic atoms in the molecule.
R As~AS~As-As-As
l , R = tBu
[*] Prof. Dr. M. Baudler, Dr. S. Wietfeldt-Haltenhoff
lnstitut fur Anorganische Chemie der Universitat
Greinstrasse 6, D-5000 Koln 41 (FRG)
Contributions to the Chemistry of Arsenic, Part 7. This work was supported by the Minister fur Wissenschaft und Forschung des Landes
Nordrhein-Westfalen and the Fonds der Chemischen 1ndustrie.-Part 6:
Anyew. Chem. In!. Ed. Engl. 24 (1985) No. 11
In addition, mainly AsgtBu7,['] A S ~ ~ B U As6fBu4,[61
and (AstBu)51s1are formed together
with small amounts of further tert-butylarsanes containing
u p to 20 arsenic atoms in the molecule.[61The product pattern is strongly dependent on the reaction conditions (molar ratio and concentration of the reactants, reaction rate,
duration of additional stirring). Under suitable reaction
conditions (optimized by ' H - N M R spectroscopic monitoring), 1 can be obtained as major product and isolated in
analytically pure form.
The dodecaarsane 1 is a bright yellow, crystalline solid
(decomposition with browning above 237"C), which is
stable at room temperature in the absence of air and light.
It is readily soluble in aliphatic hydrocarbons and THF,
moderately soluble in arenes, and only very sparingly soluble in methano1;the solutions are, in contrast to the solid
substance, thermally decomposable and extremely sensitive to oxidation and light. The composition of 1 is confirmed by an accurate elemental analysis and by a molecular weight determination (MS). The IR spectrum, unlike
those of the other tert-butylarsanes, shows an intense band
at 348 cm I.
Since we have so far been unable to obtain single crystals for an X-ray structure analysis, the structure proposed
for 1 is based on NMR and mass spectroscopic findings.
The 'H-NMR ~pectrurn[~"l
shows eight, partially overlapped signals at S = 1.54, 1.59, 1.60, 1.61, 1.63, 1.65,1.69, and
1.75 (in [DJbenzene, 24"C), the intensity ratio of which indicates the presence of two configurational isomers'"'' with
C 1symmetry in the ratio 5 : 1. The chemical shifts lie in the
region characteristic for tert-butyl-substituted five- and sixmembered arsenic rings,I3 '] while three- and four-membered rings[' '. '*]-and thus also seven-membered ringscan be ruled out as structural units. This i s confirmed by
the I3C('H)-NMR s p e c t r ~ m [ ~which
~ l , shows two slightly
structured signal humps at 6 ~ 3 2 . 3and 33.5 (in [DJbenzene, 24°C) for the primary and tertiary C-atoms, respectively, of the tert-butyl groups. Of the possible isomers,
whose skeletal frameworks consist only of arsenic fiveand/or six-membered rings, only a tricycle of an As8-skeleton analogous to pentalane with an annelated six-membered ring comes into question for 1 on taking into consideration the steric interactions of the substituents and the
observed C , symmetry. This is further supported by the
mass spectrum (10 eV, 180"C), in which, aside from the
(M- Bu)@ ion, primarily five-membered ring/six-membered ring and five-membered ring/five-membered ring
fragments of comparably high intensity occur. 1 is thus a
3,4,5,7,9,10,11,1 2-octa-tert-butyltricyclo[
The configuration and conformation of the structural
unit analogous to pentalane should be the same as in
A S ~ ~ B Uwith
~ , ' the
~ ~ substituents in the exo-coupled sixmembered ring arranged predominantly in the trans position in both isomers.
Due to its "open" tricyclic Asl2 skeleton, compound 1
decomposes on heating in solution with formation of
mono-, bicyclic, and higher annelated polycyclic tert-butylarsanes.
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99 I
According to mass spectroscopic investigations, the element-homologous phosphorus compound PlztBus likewise
exists; however, because of difficulties encountered in its
isolation, the structure of this homologue has not yet been
A solution of tBuAsCI,, (22.36 g, 0.1 1 mol) and AsCI, (13.32 g, 0.073 mol) in
T H F (95 mL) is added dropwise within 90 min to a vigorously stirred suspension of magnesium turnings (5.36 g, 0.22 mol: previously etched by evaporating a few grains of iodine) in boiling T H F (120mL). The black mixture is
refluxed for a further 35 min and then the solvent completely removed at
room temperature under reduced pressure. The brown residue is treated with
450 mL of n-pentane and the resulting mixture stirred for 3 h. The undissolved material is separated off by suction filtration, washed with 2 x 20 mL
of pentane, and the solvent is again removed from the combined filtrates.
The remaining yellow solid is dissolved in 15 mL of pentane and chromatographed on A120, using pentane at -50°C with 'H-NMR spectroscopic
monitoring (9-cm column, 4.5 cm internal diameter; packing: neutral A1203
(according to Brockmann), particle size 0.063-0.200 mm, heated in vacuo and
gassed with argon: amount of solvent: 4000 mL: duration 5.5 h]. After combination of the fractions containing the largest amounts of 1 , final purification is accomplished by crystallization at -25°C or by preparative HPLC
[ I I] (Nucleosil-5-CS column, methanol/n-pentane (91.5 :8.5); receiver:
-78°C): yield 1.3 g of pure 1 (7% w.r.t. fBuAsCI,: not optimized).
Received: July 1 1 , 1985:
supplemented: August 13, 1985 [Z 1382 IE]
German version: Angew. Chem. 97 (1985) 986
[I] Reviews: a) M. Baudler, Angew. Chem. 94 (1982) 520: Angew. Chem. I n t .
Ed. Engl. 21 (1982) 492: b) M. Baudler, V. Arndt, Z. Naturjorsch. 8 3 9
(1984) 275: c) M. Baudler, Z. Chem. 24 (1984) 352.
[2] H. G. von Schnering, D. Fenske, W. Honle, M. Binnewies, K. Peters,
Angew. Chem. 91 (1979) 755: Angew. Chem. I n f . Ed. Engl. 18 (1979)
[3] M. Baudler, J. Hellmann, P. Bachmann, K.-F. Tebbe, R. Frbhlich, M.
Feher, Angew. Chem. 93 (1981) 415; Angew. Chem. Int. Ed. Engl. 20
(1981) 406.
[4] M. Baudler, S. Wietfeldt-Haltenhoff, Angew. Chem. 96 (1984) 361: Angew. Chem. I n f . Ed. Engl 23 (1984) 379.
[S] In this connection, the polyarsenide ion As:r should also be mentioned:
C. H. E. Belin, J. Am. Chem. SOC.102 (1980) 6036.
(61 M. Baudler, S. Wietfeldt-Haltenhoff, P. Bachmann, Chem. Ber., in
[7) A. Tzschach, V. Kiesel, J. Prakt. Chem. 313 (1971) 259.
[8] M. Baudler, P. Bachmann, Z . Anorg. ANg. Chem. 485 (1982) 129.
[9] a) Measuring frequency 300.13 MHz: b) measuring frequency 75.47
[lo] The HPLC peak of 1 [ I l l shows a virtually pure Gauss function, so the
occurrence of constitutional isomers can be ruled out.
[ 1 I] M. Baudler, M. Pieroth, unpublished.
[I21 M. Baudler, P. Bachmann, Angew. Chem. 93 (1981) 112: Angew. Chem.
Int. Ed. Engl. 20 (1981) 123.
[13] M. Baudler, M. Michels, unpublished.
fur compounds."-31 For this purpose, polysilane-sulfur systems appeared to be particularly attractive, allowing the
properties of the polysilanes to be combined with those of
the silathianes. Nothing was known about these substances
u p to now, even though there has been a surge of interest
in recent years in acyclic and cyclic polysilanes as well as
in Si-S chemistry (3400 and 1850 compounds, respectively,
although structure analyses are available for only 40 and
11, re~pectively'~]).
1,2,2,3,3,4,5,5,6,6-Decamethyl-7-thia-l,2,3,4,5,6-hexasilanorbornane (CH3),,Si,S lf5]
is formed in a surprisingly
simple and straightforward reaction from 1,4-dichlorodecamethylcyclohexasilane and HZSwith elimination of HCl.
1 crystallizes as colorless needles, which are very sensitive
to moisture and decompose thermally above 240°C without melting. IR measurements had to be carried out in CS2
since 1 reacts even with CCI,.
1 has a very slightly distorted mm2-Cz, symmetry. Immediately apparent in the X-ray diffraction structure (Fig.
1) is the size and orientation of the ellipsoids of thermal
vibration, which, at first glance, indicate a separate vibration of the Si-S-Si structural unit. The analysis, using the
model of a rigid body,"' shows, however, that the entire
molecule behaves like a rigid body, which has important
consequences for the analysis of bond lengths. If the vibrations are initially ignored, then the distances and angles
shown in Figure 1 are obtained.
The mean Si-S (216.9 pm) and Si-Si bond lengths (234.2
and 234.6 pm) fall in the usual range. This also holds for
the Si-C distances (187.4, 187.3, 188.0 pm), which are not
significantly influenced by the position of the substituents
in the molecule. The notable ellipsoids of all the atoms can
be described very well using the model of a rigid body
( R = 0.07), especially those of the ring atoms ( R = 0.03). In
the crystal, the molecule vibrates about a center on the
twofold axis (Fig. 1) that does not coincide with the center
of gravity. The maximum values of the librational and
By Wiesiaw Wojnowski, Boguslaw Drqczewski,
Aleksander Herman, Karl Peters, Eva-Maria Peters, and
Hans Georg von Schnering*
Dedicated to Professor Max Schmidt on the occasion of
his 60fh birthday
We have recently investigated intensively the relationships between the structures and properties of silicon-sul-
a i = 04.00
a2 = 102.1O
63 = 1M).4°
a4 = 1 1 4 . 7 ~
a6 = 114.6O
= 106.60
= 114.00
a8 = 100.3'
aS = 110.8O
a10 = 108.2O
[*] Prof. Dr. H. G. von Schnering, Dr. K. Peters, E:M.
Max-Planck-lnstitut fur Festkorperforschung
Heisenbergstrasse I , D-7000 Stuttgart 80 (FRG)
Prof. Dr. W. Wojnowski, Mgr. 9. Dreczewski, Dr. A. Herman
Institytut Chemii i Technologii Nieorganicznej
Politechnika Gdanska, PL-80.952 Gdansk (Poland)
Contributions to the Chemistry of Silicon-Sulfur Compounds, Part 31.Part 36: [I].
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a1 1
Fig. I . Crystal structure of 1 with ellipsoids of thermal vibration (above) and
the average bond lengths d l L d 6 and bond angles al-all (below). The position of the twofold axis (dashed line), the center of gravity (e, and the center
of vibration (0)are shown (arrow). The position of the H atoms is given in
the upper part.
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Angew. Chem. Int. Ed. Engl. 24 (1985) No. I 1
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as12tbu8чa, tricyclo
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