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Cyclo[d.e.d.e.e.d.e.d.e.e

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The molecule 6 contains two nearly planar systems (the
two five-membered rings with Si(CH,), and methyl
groups), which form an angle of 11 1.4" to each other. If
the phenyl groups are excluded, the molecule has a mirror
plane through C11, BI, S11, and S6 (see Fig. 1).
in 150 mL of CCI,. After 12 h of heating at reflux, the reaction mixture was
filtered to separate the solvent, and 6 was sublimed at IOO"C/2 x lo-' mbar;
colorless crystals, m.p. = 102"C, yield 33%.
Received: February 4, 1986:
revised: May 27, 1986 [Z 1655 IE]
German version: Angew. Chem. 98 (1986) 717
CAS Registry numbers:
3a, 9441 1-17-3; 4, 19125-66-7: 6 , 103348-98-7; 6 B(III), 103348-97-6
C. Habben, A. Meller, M. Noltemeyer, 0. M. Sheldrick, J Organomel.
Chem. 288 (1985) 1 .
C. Habben, A. Meller, Z . Nafurforsch. 839 (1984) 1022.
Systematic name of 6 : 2,3,5,6,8,8,10,10-octamethyl-4-pheny1-9,1
l-dithia1,3,5,7-tetraaza-8, IO-disila-2,4,6-triboratricyclo[5.3.
I .04 "Iundecane.
H. Noth, R Staudigl, Chem. Ber. 115 (1982) 813.
W. Isenberg, R. Mews, Z . Nalurforsch. 837 (1982) 1388.
Gmelins Handbuth der Anorganischen Chemie. Bd. 51. Boruerbindungen
Tell 17, Springer, Berlin 1978.
H. Noth, Z Narurforsch. 838 (1983) 692.
NMR, Bruker AM 250, ' H (CDC13/TMS int.): 6=0.38 (s, B-CH,, 6H),
0.53 (s, Si-CH3, 6H), 0.61 (s, Si-CH,, 6H), 2.76 (s, N-CH,, 6H), 7.257.42 (br., C,Hs, 5H). - "C (CDCIJTMS int.): 6= - 1.21 (B-CH,), 5.30
(Si-CH,), 6.83 (Si -CH2), 3 I .81 (N-CH3), 127.2 1 127.85, 133.86- 142.8 1
(B-C/C,H,).
H. Noth, B. Wrackmeyer: Nuclear Magnetic Resonance Spectroscopy of
Boron Compounds, Springer, Berlin 1978.
Ci721
Sl61
~
Fig. I. Crystal structure of 6 (unsymmetrically numbered). Space group
P2,2,2,, a=715.4(1), b= 1573.3(4), c=2017.0(5) pm, V=2.2702 nm3, Z = 4 ,
u(MoKn)=0.33 m m - ' ; R,=0.046, R=0.051 for 1490 unique reflections with
F > 3 o(F);MoKCc
radiation, 28,,,=45°.
Important bond lengths [pm]: BIS I I 204.4(8). SI ILN4 168.1(5), S l l - N 8 167.8(5), B3-N4 147.6(9), B9-N8
148.1(9), N2-B3 140.0(9), N10-B9 139.2(9), BI-N2 152.4(9), BI-NIO 152.4(9),
N4-Si5 174.6(5), N8-Si7 176.3(5), Si5-S6 215.1(3), Si7-S6 214.6(3). - Further
details of the crystal structure investigation may be obtained from the
Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-75 14 Eggenstein-Leopoldshafen2 (FRG), on quoting the depository number C S D 51938,
the names of the authors, and the journal citation.
The BI-Sl1 distance (204.4 pm) is almost the longest so
far found for tetracoordinated boron (1 86-207 pmI4]). Although the NS distances (167.8 and 168.1 pm) are shorter
than those found in monocyclic compounds of type 3 (ca.
172 pm"'), they are in good agreement with those in the
bicyclic tetrasulfur hexanitrogen hexafluoroarsenates
(168-169 pm'']), which also contain three-coordinate sulfur. The BN bonds can be divided into three groups: single
bonds between both N2 and N10 and the tetracoordinated
B1 (152.4 pm); bonds having considerable double bond
character when both atoms bear methyl substituents (139.2,
140.0 pm, compare 139-144 pm in b o r a ~ i n e s ~ ~and
. ~ ~the
);
B3-N4 and B9-N8 bonds (147.6, 148.1 pm), which have
intermediate lengths.
In the 'H-NMR spectrum,[81the methyl groups on the Si
atoms give rise to two singlets; two types of Si-CHI
groups are also apparent in the I3C-NMR spectrum.[81 "BNM R signals appear for three-coordinate boron"I at
6=35.7 and for four-coordinate boron at 6 = 13.7 (CDC13/
BF3.0(C2H,), ext., intensity ratio ca. 2 : l ; no changes in
the chemical shifts or in the intensity ratios were observed
at +60°C). The I4N-NMR and 29Si-NMR spectra show a
broad singlet (I4N: CDCI3/H3CNO2ext., 6= -285.7) and
a sharp singlet ("Si: CDC13/TMS int., 6= 19.39), respecmbar.
tively. Compound 6 sublimes at 100°C and 2 x
Heating of 6 over several hours under argon in a sealed
tube at 150°C results in partial decomposition. Protic solvents result in decomposition of 6 with the formation of
H2S.
Experimental Procedure
A mixture of 4 (1.90 g, 12.8 mmol) and triethylamine (5.18 g, 51 mmol), dissolved in 50 mL of CCI,, was added to a solution of 3a [2] (4.24 g, 12.8 mmol)
742
0 VCH Verlagsgerellschafi mbH. 0-6940 Weinherm. 1986
Cyclo[d.e.d.e.e.d.e.d.e.e.jdecakisbenzene,
a New Cycloarene**
By Dirk J. H.Funhoff and Heinz A. Staab*
The only example known so far for the class of cycloarenes has been kekulene,"] for which spectroscopic investigations and X-ray diffraction studies revealed a remarkably limited n-electron delocalization in the planar macrocyclic system (formula l).lzl Other cycloarenes, which are
of interest with regard to their electronic structure, have
not yet been prepared.r3,41For instance, the attempt to synthesize cyclo[d.e.d.e.e.d.e.d.e.e]decakisbenzene2IS1by photocyclization of [2.2](3,1O)benzo[c]phenanthrenophaneI , I 5-diene resulted only in ring closure on one side to give
a helical system, the rigid structure of which presumably
hinders the second ring closure to give 2.I3l A modified
synthetic strategy based on this assumption has now allowed us to prepare 2 , which contains the [14]annulene
skeleton as the inner ring system and, as in the case of 1,
can be formulated with an outer and an inner [4n+2] n
perimeter (2a).
The key reaction for the synthesis of 2 should be the
double photocyclization of the partially hydrogenated
[2.2](3,1O)benzo[c]phenanthrenophanediene
3,
which
would result in formation of the carbon skeleton of 2 ; subsequent dehydrogenation should then give 2. Compound
3 was obtained, starting from bis(4-chlorophenyl)chloromethane via the following 18-step route. The product
(m.p. =99-1OO0C; 70%)16' obtained by reaction of the starting material with diethyl malonate (sodium hydride, dimethylformamide (DMF), 3 h, 100°C) was reduced with
[*I Prof. Dr. H. A. Staab, DipLChem. D. J. H. Funhoff
Abteilung Organische Chemie,
Max-Planck-Institut fur medizinische Forschung
Jahnstrasse 29, D-6900 Heidelberg
I**] Cycloarenes, a New Class of Aromatic Compounds, Part 5.-Part
141.
0570-0833/86/0808-0742
$
02.50/0
4:
Angew. Chem. In!. Ed. Engl. 25 (1986) No. 8
was converted into the dicyano compound 10 (m.p. = 181183°C)[61by reaction with copper(1) cyanide in N-methyl2-pyrrolidone (24 h, reflux; 78%); 10 reacted with hydrogen chloride in rnethanoVchloroform to give the dimethy1 ester 11 (m.p.= 136-137°C; 95%).[" Reduction of 11
(LiAIH4, THF; 93%) led to 13 (m.p. = 108-1 1I OC),['] which
was converted into the bis(bromomethy1) compound 14
(m.p. = 114-1 15°C; 69Y0)[~'by treatment with hydrogen
bromide/glacial acetic acid. Compound 14 is the first cyclization component required for the synthesis of the dithiaphane 17. The double isothiuronium salt 15
(m.p. = 144"C, dec.)@],the second cyclization component,
was obtained by treatment o f 14 with thiourea (ethanol, 30
min, reflux; 84%).
1
2
3
6
15
1L
10
11
x
2a
2
LiAIH, in tetrahydrofuran (THF) to give the diol 4
(m.p.= I 18°C)i61in 78% yield; 4 was then converted, by
reaction of the corresponding bis(methanesu1fonate) 5[61
(methanesulfonyl chloride, pyridine, - 5°C; m.p. = 143144°C; 89%) with potassium cyanide (DMF/water; 66%),
into the dinitrile 6 (m.p. = 107-108°C).[61 Hydrolysis (sodium hydroxide, ethanediol, 6 h, 160°C; 90%) afforded the
dicarboxylic acid 7 (m.p.= 1 18"C),[61which was cyclized
with polyphosphoric acid to give 3,10-dichloro-5,8-dioxo5,6,6a,7,8,12b-hexahydrobenzo[c]phenanthrene 8 (m.p. =
227-23 1 "C, dec.; cis-trans mixture 6a,12b-H)I6] in 90%
yield.
6
XH2C
2
9:
x
10: X
13: X
c1
CH2 X
=
OH
14: X = Br
= CN
11: X = COOMe
15: X = [SC(NH2)2]Br
16: X = [P(C6H5)3]Br
12: X = CHO
16
7
23
2
15
1
16
21
=
fi
3
2-0
Ac,
CI
CI
4: X
5: X
6: x
=
OH
=
OSO M e
2
=
CN
7: X
=
COOH
8
Reduction of 8 (red phosphorus, hydrogen iodide, glacial acetic acid, 5 d, reflux) gave a mixture of the cis compound 9 and its trans isomer (1 :2, total yield 88Yo), which
could be separated by crystallization (cis: m.p. = 138139°C; trans: m.p.= 151'C).@] When 8 was reduced and
then heated with potassium hydroxide in ethanediol for 1 h
at 160°C, only the cis compound 9 was formed-as is the
case for the Wolff-Kishner reduction of 8. Compound 9
Angew. Chem. Inr. Ed. Engl. 25 (1986) No. 8
22
The cyclization was carried out by simultaneous addition of solutions of 14 in toluene and 15 in methanol to
boiling methanol containing potassium hydroxide; a 30%
yield of 6,7,7a,8,9,13b,21,22,22a,23,24,28b-dodecahydro2,17-dithia[3.3](3,1O)benzo[c]phenanthrenophane (m.p.=
267-269"C, dec.)I6]was obtained. Only one of the two possible isomers was isolated, the assignment of which was
not possible on the basis of the N M R spectra;"' the X-ray
structure analysis of the phanediene 3 obtained from this
dithiaphane, however, showed that 17 must be present.
In order to synthesize 3, compound 17 was converted
into the 2,17-dimethyl-2,17-dithioniabis(fluorosulfonate)
(m.p.= 189"C, dec.) by reaction with methyl fluorosulfonate. The product then underwent rearrangement to give the
carbocyclic 1,15- and 1,I 6-bis(methylthio)-substituted
[2.2]phanes (m.p.= 161-175"C, dec.; 96%)["] upon treatment with potassium tert-butoxide in THF. Subsequent
treatment with m-chloroperbenzoic acid in dichloromethane at - 25 "C gave the double sulfoxide, which was pyrolyzed (sealed tube, 6 h, 170"C, under argon atmosphere).
[2.2](3,10)-5,6,6a,7,8,12b,19,20,20a,2 1,22,26b-dodecahydrobenzo[c]phenanthrenophane- 1,15-diene 3 (m.p. = 226230"C)[61was thereby obtained in 17% yield.
The synthesis of 3 was also attempted by double Wittig
reaction (lithium hydroxide, dichloromethane/waterixl) of
12 (obtained from 13 with pyridinium chlorochromate,
55V0)[~'with 16 (obtained from 14 with triphenylphos-
0 VCH Verlagsgesell.TchajimbH, 0-6940 Weinheim, 1986
0570-0833/86/0808-0743 $ 02.50/0
743
phane in D M F ; 98%).16' However, 3 was obtained in only
5% yield; in addition, the second possible isomer
(m.p. = 295-302"C, dec.)16]was isolated in 2% yield.
The structure of 3 cannot be unequivocally established
from the 'H-NMR spectrum;""] X-ray structure analysis,
on the other hand, proved successful.["' As revealed in
Figure 1, the molecule is not strained; this was predicted
from examination of models and force field calculations.
In the crystal, the distance between the atom pairs C11/
C28 and C14/C25 in the two cis-stilbene units is relatively
short (342 pm); it is between these two pairs of atoms
where bond formation is expected to occur photochemically.
18
Fig. I Molecular model of 3 based o n the X-ray structure analysrs [ I I ]
In order to carry out the photocyclization, 3 was irradiated in n-propylamine under argon for 6.5 h at -32°C
with a low-pressure mercury lamp; a mixture of various
hydrogenated derivatives of 2 was obtained in 35% yield
(after chromatography). Dehydrogenation with 2,3-dichloro-5,6-dicyano-p-benzoquinone
(DDQ) in m-xylene (54
h, 90°C) afforded a 13% overall yield of 2 in the form of
yellow crystals (m.p. > 330°C, dec.). The mass spectrum exhibits the molecular ion peak m / z 500 as the base peak in
addition to the peak of the multiply charged molecular
15.5%), 166.7 ( M 3 + , 1.9) and 125
ions (m/z 250 (M2+,
( M 4 + , 7.0)]. The high-resolution mass spectrum confirms
the composition (calcd 500.1565; found 500.1575). Of interest, moreover, is the (M-4)+ peak ( m / z 496, 13.6%;
high-resolution
spectrum: calcd 496.1252, found
496.1250); it apparently arises by cleavage of the four inner hydrogen atoms with transannular C-C bond formation.
The 'H-NMR spectrum of 2 (360 MHz) was recorded at
150°C in [D2]1,2,4,5-tetrachlorobenzene.In accordance
with the symmetry of 2, only five signals of equal intensity
are observed: 6=8.11 (s; 6,7,14,15-H), 8.11 (d, J=8.3 Hz;
2,3,10,11-H), 8.29 (d, J e 8 . 3 Hz; 1,4,9,12-H), 8.65 (s;
5,8,13,16-H), and 9.56 (s; 17,18,19,20-H); the signals were
assigned on the basis of NOE experiments. The low-field
shift of the inner protons shows that, as in the case of kekulene, no significant diatropism of the macrocyclic system exists.
The UV spectrum is similar to the UV spectra of benzo[cJphenanthrene and pentaphene and is therefore in accord with the benzenoid character of 2. The zero-field
splitting parameter, ID I, determined from the phosphorescence emission by the O D M R method, is significantly
smaller for 2 (0.0881 cm - in [D2]1,2,4,5-tetrachlorobenzene, 1.3 K)"'' than for kekulene (0.10622 cm-I). This indicates a less pronounced localization of sextets and double bonds than in kekulene. Indeed, it is possible to write
more than one formula for 2 with the maximum number of
744
0 VCH Verlagsgesellschaft mbH. 0-6940 Wernheim. 1986
possible sextets, whereas this is not so for kekulene in formula 1 . We hope to further clarify the electronic structure
of 2 by X-ray structure analysis and by additional spectroscopic investigations.
Received: May 28, 1986 [Z 1793 I€]
German version: Angew. Chem. 98 (1986) 757
CAS Registry numbers'
1, 15123-47-4; 2, 15123-45-2
[I] a) H. A. Staab, F. Diederrch, Chem. Ber. 116 (1983) 3487; b) see also F.
Diederich, H. A. Staab, Angew. Chem. YO (1978) 383: Angew. Chem. Inf.
Ed. Engl. 17(1978) 372.
121 H. A. Staab, F. Diederich, C. Krieger, D. Schweitzer, Chem. Ber. 116
(1983) 3504: see also C. Krieger, F. Diederich, D. Schweitzer, H. A.
Staab, Angew. Chem. 91 (1979) 733; Angew. Chem. Int. Ed. Engl. 18
(1979) 699; D. Schweitzer, K. H. Hausser, H. Vogler, F. Diederich, H. A.
Staab, Mol. Phys. 46 (1982) 1141.
[3] H. A. Staab, F. Diederich, V. Caplar, Liebigs Ann. Chem. 1983, 2262.
141 H. A. Staab, M. Sauer, Liebrgs Ann. Chem. 1984, 742.
IS] For the nomenclature of cycloarenes, see ref. [la]. According to Chemical Abstracts rules, 2 is named 13,19: 14,18-dimethenoanthra[l,2-a]ben~ ~ [ o j p e n t a p h e nwhich,
e,
however, reveals only poorly the structure and
geometry of 2. There are no lUPAC rules that apply to this class of
compounds.
I61 Elemental analyses and spectroscopic data are in accord with the structure given.
(71 17: 'H-NMR (360 MHz, CDCII): 6= 1.36-1.46 (m, 4 H ; 7,8,22,23-H,,),
1.84-1.92 (m, 4 H ; 7,8,22,23-H,,), 2.29-2.35 (m, 2 H : 7a,22a-H), 2.61-2.77
(m, 8 H ; 6,9,21,24-H), 3.51 and 3.76 (AB, Jns=13.5 Hz, 8 H ; 1,3,16,18H), 3.86 (d, J = 5 , 0 Hz, 2 H : 13b,28b-H), 6.67 (dd, J=7.9 Hz and 2.0 Hz,
4 H ; 12,15,27,30-H), 6.89 (d, J = 2 Hz, 4 H ; 5,10,20,25-H), 6.97 (d, J = 7 . 9
Hz, 4 H : 13,14,28,29-H).-")C-NMR (90.6 MHz, CDCII): 6=27.1, 27.9,
32.4, 36.0, 42.3, 126.4, 129.1, 130.4, 136.8, 137.2, 137.5.-MS (selected):
m / z 584 (50"/0, M + ) , 292 (12), 291 (17), 261 (17), 259 (100).
[8] A. Minsky, M. Rabrnovitz, Synthesis 1983, 497.
191 G. Rohlfs, Diplomarberr, Universitat Heidelberg 1985.
[lo] 3: 'H-NMR (360 MHz, C,D6): 6=1.08-1.18 (m, 4 H ; 6,7,20,2I-H.,,),
1.52-1.56(m,4H;6,7,20,21-H,,), 2.08-2.14(m,2H;6a,20a-H),2.21-2.28
(m, 4 H : 5,8,19,22-H.,,), 2.39-2.48 (m. 4 H : 5,8,19,22-H,,), 3.65 (d, J = 5 . 0
H z , 2 H ; 12b,26b-H),6.74(d,J=7.8Hz,4H; 12,13,26,27-H),6.77(~,4H;
1,2,15,16-H),6.87 (d, J=1.9 Hz, 4 H : 4,9,18,23-H),6.99(dd, J = 7 . 8 and
1.9 Hz, 4 H : I 1,14,25,28-H).
11 I ] C. Krieger, D. J. H. Funhoff, H. A. Staab, unpublished results.
1121 D. Schweitzer, unpublished results.
An Isocyanide Radical as Complex Ligand**
By Friedrich Seitz, Helmut Fischer, * Jurgen Riede,
Thomas Schottle, and Wolfgang Kaim
Structurally, the CNCR, ligand in complexes of the type
[L,M(CNCR2)]' is unusually flexible. In the pentacarbonyl cations
[(CO),M(CNCR,)]@ (M = W, C r ; compare 1 and 5, respectively)
the M-C-N-C fragment is nearly linear;['] these cations
are best described as resonance hybrids of the structures A
and B.
e
(C0)5M=C=N=CR2
A
Q
@
@
* (CO)~M-CEN-CR~
B
[*] Priv.-Doz. Dr. H. Fischer, Dr. F. Seitz, J . Riede, Dr. T. Schottle
[**I
Anorganisch-chemisches lnstitut der Technischen Universitat Munchen
Lichtenbergstrasse 4, D-8046 Garching (FRG)
Priv.-Doz. Dr. W. Kaim
Institut fur Anorganische Chemie der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (FRG)
Metallaheterocumulenes, Part 6. This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der Chemischen
1ndustrie.-Part 5 : [9]
0570-0833/86/0U08-0744 $ 02.50/0
Angew. Chem. Int. Ed. Engl. 25 (1986) N o 8
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