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Bis(2 4 6-tri-tert-butylphenyl)bicyclotetraphosphane.

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pounds, presumably oligomers. In glacial acetic acid
(CH3C0,H/CH2C12=3:2, i=40 mA/cm2, T=2OoC, Pt
electrode) 17% androstanyl acetate is obtained and 38%
androstane is recovered. Remarkable is the selectivity of
the oxidation: We found that the 6- (6a), 7-, and 12-acetates are formed in the ratio 35 :1 : 2 S ; other acetates could
not be detected by us. Assignment of the structures was
accomplished by hydrolysis, oxidation to the ketone, and
comparison of the mass spectra with those given in the literature. The main product was characterized ',C-NMR
spectroscopically as 6a-acetoxy-5a-androstane (6a). The
electrolysis in methanol (methanol/dichloromethane,
0.1 M NaCIO,, glassy carbon electrode) proceeds even
more selectively. At a 53% conversion (47% androstane recovered) 14% 6-methoxyandrostane (7a) and 27% 6-(methoxymethoxy)androstane (Sa) were formed.
R
R
X
fi
Y
a, R = H b, R =
6 , X = OAc; 7. X = OCHS;
In glacial acetic acid, cholestane affords 15%cholestanyl
acetates; the 6-(6b), 7-, and 12-acetates are formed in the
ratio 40 : 1 :2. In methanol, 50% conversion was observed
with formation of 15% 6-methoxycholestane (7b) and 25%
6-(methoxymethoxy)cholestane (Sb). These findings reveal
a surprising and remarkable selectivity. Of the 32 hydrogen
atoms in androstane and the 48 in cholestane, predominantly only those on C-6 are oxidized. Acetates or methyl
ethers originating from attack at the reactive tertiary hydrogen atoms on C-5, C-9, C-14, and, in the case of cholestane, also those on C-17, C-20, and C-25 are not found. An
explanation for this would seem premature, but the selectivity could be effected by an association of the steroid molecules. In stacked androstane and cholestane, the tertiary
hydrogen atoms would be shielded, while on the front and
rear side of the stack the hydrogen atoms on C-6, C-7, and
C-12 would be exposed to the electrode for the electron
transfer.
The methoxymethyl ethers 8 could be formed by secondary oxidation of the methyl ethers 7.[*] That the less
reactive but obviously more easily accessible methyl group
is hereby oxidized, and not the methine hydrogen, could
be a further indication of the formation of stacked associates.
Thus, the anode is a cheap and easily employable reagent for the oxidation of CH-bonds. The chemoselectivity
of the anode compares favorably with other reagents; Ri,
the ratio of the rate of attack at tertiary and secondary CH
bonds, is 12 for decalin.['I The regioselectivity can be controlled by inductive effects. The steroid hydrocarbons androstane and cholestane are remarkably regioselectively
oxidized at C-6.
Experimental
A solution of 5a-androstane (Sa) (260 mg, 1 mmol) in CH2C12 (20 mL), methanol (30 mL), and NaC10, (0.612 g, 0.1 M) was electrolyzed at 20°C with a
current density of 30 mA/cm2 at a glassy-carbon anode (21 cm2) in an undivided cell until consumption of 965 As. Gas chromatographic analysis (60m
capillary column, 0.3% SE 52) of the crude product revealed the presence of
14% 7a, 27% 8a, and 47% 5a (calibrating standard: n-octadecane). The crude
product was treated with sodium methoxide and, after removal of the solvent, the residue was taken u p in cyclohexane and the supporting electrolyte
1056
0 VCH Verlagsgesellschafi mbH, 0-6940 Weinheim, 1985
removed by filtration. HPLC separation (CH,CI,:n-hexane, 1 : 1) yielded
98 mg (38%) Sa, 29 mg (10%) 7a ("C-NMR, INEPT), and 67 mg (21%) 8a.
8a was hydrolyzed with HCI in methanol to 5a-androstan-6a-ol ("C-NMR
comparison with 6a-androstanol [lo]).
Received: July 15, 1985;
revised: September 16, 1985 [Z 1390 IE]
German version: Angew. Chem. 97 (1985) 1048
[I] J. Mulzer, Nachr. Chem. Tech. Lab. 32 (1984) 520.
[2] R. Breslow, Acc. Chem. Res. 13 (1980) 170; U. Korb, M. Stahnke, P. E.
Schulze, R. Wiechert, Angew. Chem. 93 (1981) 89; Angew. Chem. Int. Ed.
Engl. 20 (1981) 88.
[3] J. Bertram, J. P. Coleman, M. Fleischmann, D. Pletcher, J. Chem. SOC.
Perkin Trans. 2 1973, 374; D. B. Clark, M. Fleischmann, D. Pletcher,
ibid. 1973, 1578; G. J. Edwards, S. R. Jones, J. M. Mellor, ibid. 1977,
505; H. P. Fritz, T. Wurminghausen, J. Chem. SOC.Perkin Trans. I 1976,
610; Z . Naturforsch. 8 3 2 (1977) 241.
[4] E. Cramer, A. Hembrock, H. J. Schafer, unpublished: In CH2Clz/20%
trifluoroacetic acid/4% trifluoroacetic anhydride (0.05 M Bu4NPF6) at
0"C, cyclohexane yields 92% cyclohexyl trifluoroacetate at the Pt anode:
cyclopentane: 84% cyclopentyl trifluoroacetate: norbornane: 90% exo2-norbornanol (after hydrolysis); bicyclo[2.2.2]octane: 68% bicyclo[3.2.1]octan-2-ol, 3% bicyclo[2.2.2]octan-2-ol, and 13% bicycIo[2.2.2]octan- 1-01 (after hydrolysis).
[5] N. C. Deno, W. E. Billups, R. Fishbein, C. Pierson, R. Whalen, J. C.
Wickhoff, J. Am. Chem. SOC.93 (1971) 438; F. Kamper, H. J. Schafer, H.
Luftmann, Angew. Chem. 88 (1976) 334: Angew. Chem. Int. Ed. Engl.. IS
(1976) 306.
[6] G. Olah, D. G. Parker, N. Yoneda, Angew. Chem. 90 (1978) 962; Angew.
Chem. Int. Ed. Engl. 17 (1978) 909; B. Westrup, Dissertation, Universitat
Munster 1981.
[7] D. Pletcher, C. 2. Smith, J. Chem. SOC.Perkin Trans. I 197s. 948.
[XI a) T. Shono, Y. Matsumura, J. Am. Chem. SOC.91 (1969) 2803.
[9] The oxidation of decalin at 20°C with chlorine in benzene or in CS2 or
with C6HSICIZin benzene proceeds with R:=6.3, 10.5, and 8.3, respectively. F. Kimper, Dissertation, Universitat Munster 1979.
[lo] G. M. Schwentzer, J. Org. Chem. 43 (1978) 1079.
Bis(2,4,6-tri-ter?-butylphenyl)bicyclotetraphosphane
By Ralf Riedel, Hans-Dieter Hausen, and
Ekkehard Ruck*
So far, approximately twenty polycyclic organophosphanes have been isolated and characterized;['.21 in addition, a few further representatives of this class of compounds have been detected spectros~opically.['-~~
We have
now been able to synthesize bis(2,4,6-tri-tert-butylpheny1)bicyclotetraphosphane 1, a derivative of the simplest
bicyclic phosphane P4H2.1 is formed along with bis(2,4,6tri-tert-butylpheny1)diphosphene 2I4l upon reaction of
2,4,6-tri-tert-butylphenyllithiumand I-bromo-2,4,6-tri-tertbutylbenzene with white phosphorus. Thus, it has been
possible for the first time to isolate a product of the reaction of white phosphorus whereby only one bond of the P4
tetrahedron is opened.
4RLi + 4 RBr+ 3 P4
R = 2,4,6-tBu&,H2
2 R2P,+ 2 R2P2+4LiBr
1
2
1 is ivory-colored, slightly sensitive to oxidation, stable
at room temperature, and soluble in chloroform. The
3'P('H}-NMRspectrum (CDCI,; standard: 85% H,PO,) of
[*I Prof. Dr. E. FIuck
Gmelin-lnstitut fur Anorganische Chemie der Max-Planck-Gesellschaft
Varrentrappstr. 40/42, D-6000 Frankfurt am Main 90 (FRG)
Dr. H.-D. Hausen, R. Riedel
Institut fur Anorganische Chemie der Universitat
Pfaffenwaldring 5, D-7000 Stuttgart 80 (FRG)
0570-0833/85/(/1212-1056 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 24 (1985) No. 12
1 shows two multiplets, 6= -272 (bridgehead P atoms)
and 6 = - 130, while the 'H(3'P)-NMR spectrum contains
two singlets at 6= 1.27 (4-tBu) and 1.74 (2,6-tBu) as well as
a multiplet at 6=7.0. These findings are consistent with
the results of an X-ray structure analysis (Fig. l).I5'
Eggenstein-Leopoldshafen2, on quoting the depository number CSD51 578, the names of the authors, and the full citation of the journal.
161 E. Niecke, R. Ruger, B. Krebs, Angew. Chem. 94 (1982) 553; Angew.
Chem. I n t . Ed. Engl. 21 (1982) 544.
[7] D. E. Pearson, M. G. Frazer, V. S. Frazer, L. C. Washburn, Synfhesis~
19 76, 621.
Computer-Controlled Precipitation of Metal
Hydroxides and Hydrous Oxides-Preparation of
Manganese Dioxide Having Uniform Particle
Sizes**
By Dieter H . Buss, Gottjiried Schaurnberg, and
Oskar Glemser*
Fig. I . ORTEP plot of the crystal structure of 1 (vibration ellipsoids at the
50% probability level). Bond lengths [pm] and bond angles ["I: PI-F2
222.3(4), PILP4 223.5(7), P2-P3 222.2(3), P2-P4 216.6(2), P3-P4 223.6(9), PI-C
189.2(8), p3-C 188.5(1); P2PlP4 58.1(1), PlP2P4 61.2(1), PlP2P3 80.9(1),
P3P2P4 61.3(1), P2P3P4 SS.I(l), P3P4P2 60.6(1), P3P4Pl 80.4(1), P2P4Pl
60.7(1), CPlP2 98.2(1), CPIP4 97.3(1), CP3P4 99.2(1), CP3P2 97.8(1). The
numbering of the P atoms is arbitrary.
The two 2,4,6-tri-tert-butylphenyl moieties in 1 are cis
oriented. The folding angle of the P4 bicycle, 95.5", is just
about the same as that in bis(trimethylsily1amino)bicyclotetraphosphane (95.2 which has been synthesized from
diphosphanes.[6' The P-P bonds in both compounds are
(with exception of the central bond) about the same length
as normal P-P single bonds (in 1 222.2-223.6 pm); only
the central P-P bond in 1 is slightly longer (216.6 pm) than
in the bis(trimethylsily1amino) derivative (213 pm).
O),
Experimen tal
All operations were carried out under argon. A solution of l-bromo-2,4,6tri-ferf-butylbenzene [7] (61.55 g, 189.3 mmol in ether (500 mL) was treated at
room temperature with 85 mL (212.6 mmol) of a 2.5 molar solution of nbutyllithium in n-hexane. The mixture was stirred for 3 h and then treated
with 12.4 g (100 mmol) of white phosphorus. After 10 min, the resulting red
solution began to boil and was then heated at the boiling point for a further
60 min. After 24 h, the mixture was hydrolyzed. A reddish-brown oil was obtained (72 g). from which an air-stable orange-red solid crystallized which
was collected on a frit and washed with acetone. After recrystallization from
benzene, 3 g of a coarsely crystalline mixture of 1 and 2 (ca. 3 : 1) was isolated. The crystals of 1 obtained by a second recrystallization were selected
for the X-ray structure analysis.
Received: July 16, 1985;
supplemented: Sectember 10, 1985 [Z 1391 IE]
German version: Angew. Chem. 97 (1985) 1050
[I] M. Baudler, Z. Chem. 24 (1984) 352.
[2] M. Baudler, Angew. Chem. 94 (1982) 520; Angew. Chem. Inr. Ed. Engl. 21
(1982) 492.
[3] P. Jutzi, T. Wippermann, J. Organomer. Chem. 287 (1985) CS.
[4] M. Yoshifuji, 1. Shima, N. Inamoto, K. Kirotsu, T. Higuchi, J. Am. Chem.
SOC.I03 (1981) 4587.
[S] 1 crystallizes monoclinically; space group P2,/n, II = 1677.2(4),
h= 1079.7(3), c=2071.5(3) pm,b=96.01(2)"; Z=4,pcal,= 1.09 glcm'). All
atoms occupy the general positions of the space group. The structure was
derived from 5516 independent reflections (4409 observed) via direct
methods and Fourier syntheses and refined to R=0.051. Further details
of the crystal structure investigation are available on request from the
Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-75 14
Angew. Chem. I n l . Ed. Engl. 24 (1985) No. I2
It is difficult to precipitate metal hydroxides and hydrous oxides"] that always have the same properties from
aqueous solution. Recently, we were able to obtain cobalt,
nickel, and manganese hydroxides, as well as their double
hydroxides with a l u m i n ~ m , [ ~by
- ~ ] computer-controlled
precipitation at a constant pH value. Their compositions,
structures, and discharge capacities could be well reproduced. We report here on the application of this technique
to the Guyard reaction,[51 the formation of manganese
dioxide from manganese([]) salts and potassium permanganate in acidic solution.
The precipitations were carried out at the potential that
is established at an electrographite electrode (measured as
U,,, versus a Ag/AgC1//3 M KCl reference electrode), for
a given pH value of the solution, after the manganese dioxide begins to precipitate and while a small excess of MnO?
is still visible. The excess or deficiency of MnO? ions is
controlled with this potential, which remains relatively stable (k 5 mv) during the course of the precipitation (hours).
The upper control limit is U,,,,,,
the lower, the approximately 20 mV more negative potential. Between these limits, nearly stoichiometric amounts of KMn04 and
Mn(N03)2 solutions are added simultaneously during the
precipitation. When the lower limit of the potential is exceeded, KMn04 solution is added; when the upper limit is
exceeded, Mn(N03)2 solution is
Using this procedure, it has been possible, for the first
time, to prepare manganese dioxide having nearly uniform
Fig. I. Scanning electron micrograph of manganese dioxide that was precipitated with computer control at pH 0 and I (left and middle, respectively) or
without computer control at about pH 1 (right). Left: Enlargement 110 times;
potential limits 1407/1432 mV; 87.1 wt.-Yo active M n 0 2 ; particle size 70 pm:
bulk density 0.72 g/cm3; BET surface: 169 m2/g; discharge capacity
q,,,=73.9 mA h/g.-Middle:
Enlargement: 119 times; potential limits
1347/1357 mV; 80.1 wt.-% active M n 0 2 ; particle size 45 pm; bulk density
1.53 g/cm3; BET surface: 0.4 m2/g; discharge capacity q,.,=81.3
mA h/g.
-Right: Enlargement: 122 times: without control of potential: 85.7 wt.-%
active M n 0 2 ; bulk density 0.41 g/cm'; BET surface: 108 mZ/g; discharge
capacity qmrx= 11 mA h/g.
['I Prof. Dr. 0. Glemser, Dr. D. H. Buss, Dipl.-Chem. G. Schaumberg
Institut fur Anorganische Chemie der Universitat
Tammannstrasse 4, D-3400 Gottingen (FRG)
[**I This work was supported by the Akademie der Wissenschaften in Gottingen, the Fonds der Chemischen Industrie, and the Herbert-QuandtStiftung.
0 VCH Verlagsgesellschaft mbH, 0-6940 Weinheim, 1985
0570-0833/85/1212-1057~02.50/0
1057
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