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Novel NaphthaleneЦ and Cyclohexa-1 3-dieneЦSilene Cycloadducts.

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transport of iron, play a role in the transport of purine and
pyrimidine bases or nucleotides.
Received: December 11, 1990 [Z4316IE]
German version: Angew. Chem. 103 (1991) 433
[I] W. Kiggen, F. Vogtle, Angew. Chem. 96 (1984) 712; Angew. Chem. Int. Ed.
Engl. 23 (1984) 714.
[2] a)S. Grammenudi, F. Vogtle, Angew. Chem. 98 (1986) 1119; Angew.
Chem. Int. Ed. Engl. 25 (1986) 1119; b) S. Grammenudi, M. Franke, F.
Vogtle, E. Steckhan, J. Incl. Phenom. 5 (1987) 695.
[3] a) W Kiggen, F. Vogtle, S. Franken, H. Puff, Tetrahedron 42 (1986) 1859;
b) for complexes with PbZe and Bi3@see: M. Magerstadt, 0. A. Gansow,
L. K. Pannell, F. Vogtle, W Kiggen, Nucl. Med. B i d . 17 (1990) 409; c) for
complexes with alkali-metals see: J. Peter-Katalinii, F. Ebmeyer, C. Seel.
F. Vogtle, Chem. Ber. 122 (1989) 2391. d) For comparable siderands see:
T. J. McMurry, M. W. Hosseini, T. M. Garret, F. E. Hahn, Z. E. Reyes,
K. N. Raymond, J. Am. Chem. Sac. 109 (1987) 7196.
[4] a) L. De Cola, F. Barigelletti, V. Balzani, P. Belser, A. von Zelewsky, F.
Vogtle, F. Ebmeyer, S. Grammenudi, J. A m Chem. Soc. If0 (1988) 7210;
b) F. Barigelletti, L. De Cola, V. Balzani, P. Belser, A. v. Zelewsky, F.
Vogtle, F. Ebmeyer, S. Grammenudi, ibid. f f l (1989) 4662; c) P. Belser,
Chimia 44 (1990) 226; d) F. Ebmeyer, F. Vogtle. Chem. Ber. 122 (1989)
1725.
[5] a) F.Vogtle, W. M. Miiller, U. Werner, H.-W. Losensky, Angew. Chem. 99
(1987) 930; Angew. Chem. Int. Ed. Engl. 26 (1987) 901; b) A. Wallon, J.
Peter-Katalinit, U. Werner, W. M. Miiller, F. Vogtle; Chem. Ber. 123
(1990) 375; c) A.Wallon, U. Werner, W. M. Muller, M. Nieger, F. Vogtle,
ibid. 123 (1990) 859; d) F. Vogtle, A. Wallon, W. M. Muller, U. Werner, M.
Nieger, J. Chem. SOC.Chem. Commun. 1990, 158.
[6] E Ebmeyer, E Vogtle, Angew. Chem. I01 (1989) 95; Angew. Chem. Int. Ed.
Engl. 28 (1989) 79.
[7] P. Stutte, W Kiggen, F. Vogtle, Tetrahedron 43 (1987) 2065.
[8] 3.5 L, 50 "C, catalytic amounts of 4-N,N-dimethylaminopyridine,
duration
of addition 12 h, column chromatography (see Ref. [9]).
[9] The spectroscopic data ('H and 13CNMR, MS) of the new compounds are
consistent with the structures. For details of the procedures see Refs. (71
and [ 3 c ] . MS (FAB, m-nitrobenzyl alcohol) of 1 : mjr 1814 ( M e + H,
89%), 1815 ( M a + 2, 100%); of 3b: m j 1471
~
( M e + H, 88%), 1472
( M e + 2,100%); of4: mjz 1814(Me + H, 86%), 1815( M a + 2,100%).
MS (70 eV) of 5: 556 ( M e , 8%), 465 (Me-C,H,, 24%). R, values (SiO,,
CH,Cl,jethanol 20:l) of the methyl ether precursors of 1: 0.24, of 3b:
0.32, of 4:0.22, of 5: 0.41.
(101 Due to hydrogen bridge bonds, the phenolic protons show, inter alia,
smaller intensities, are shifted or disappear completely. With an empirical
for 1and 4, the host signalsclearly predominate
formula ofC,,,H,,N,O,,
compared to the guest signals.
[ l l ] Adenine hosts: a) K. Williams, B. Askew, P. Ballester, C. Buhr, K. S .
Jeong, S. Jones, J. Rebek, Jr., J. Am. Chem. Sac. lfl (1989) 1090; b) S.
Goswami, A. D. Hamilton, D. VanEngen, ibid. 1 I I (1989) 3425; c) S.C.
Zimmerman, W. Wu, ibid. 111 (1989) 8054; d) J. C. Adrian, C. S . Wilcox,
ibid. i l l (1989) 8055; Guanine hosts: e) A. D. Hamilton, N. Pant. J. Chem.
Sac. Chem. Commun. 1988,765; f) J. Rebek, Jr., Chemtracrs: Org. Chem.
2 (1989) 337; uracil and thymine hosts: g) A. D. Hamilton, D. VanEngen,
J. Am. Chem. Sac. 109 (1987) 5035; h) A. V. Muehldorf, D. VanEngen,
J. C. Warner, A. D. Hamilton, ibid. Chem. Sac. 110 (1988) 6561; cytosine
hosts: J. Rebek, Jr., K. S. Jeong, ibid. 110 (1988) 3327.
[12] Procedure as in Ref. [13b] (ultrasound, centrifugation). Guanine and pterine are so sparingly soluble in pure dichloromethane-other than on addition of the hosts-that the values lie below the error limit. The data quoted
for these two guests are estimated lowest values.
[I31 a) K. A. Connors: Binding Consrants. The Measuremenr of Molecular
Complex Stability, Wiley, New York 1987; b) F.Diederich, K. Dick, J. Am.
Chem. SOC.106 (1984) 8024.
[14] It must be remembered here that the more strongly bound guests are, at the
same time, also very sparingly soluble. That is in these cases the solvent
also competes less strongly with the hosts.
(151 a) W. H. Mandeville, G. M. Wbitesides, J. Org. Chem. 51 (1986) 3257;
b) A. Harada, S. Takahashi, J. Chem. Sac. Chem. Commun. 1987, 527;
c) M. Biihner, W. Geuder, W. K. Cries, S. Hunig, M. Koch, T. Poll, Angew.
Chem. fOO(1988) 1611; Angew,. Chem. Int. Ed. Engl. 27(1988) 1553; d) V.
Prelog, M. Dumii, Helv. Chim. Acta 69 (1986) 5 .
[16] The transport starts more quickly here but with time the rates equal the
blank values.
[17] a) M. Kirch, J.-M. Lehn, Angew. Chem. 87(1975) 542; Angew. Chem. Int.
Ed. Engl. 14 (1975) 555; b) J.-M. Lehn, Pure Appl. Chem. 51 (1979) 979;
c) J. D. Lamb, R. M. Izatt, J. J. Christensen, Prog. Macrocyclic Chem. 2
(1981) 41.
[la] a ) K . N. Raymond, G. Miiller, B. F. Matzanke, Top. Curr. Chem. 123
(1984) 49; b) R.C. Hider, Struct. Bonding (Berlin) 58 (1984) 25; c) G.
Winkelmann, D. van der Helm, J. B. Neilands (Eds.): Iron Transporr in
Microbes, Plants and Animals, VCH, Weinheim 1987.
444
0 VCH
Verlagsgesellschafi mbH, W-6940 Weinheim, 1991
Novel Naphthalene- and
Cyclohexa-1,3-diene-Silene Cycloadducts**
By Norbert Auner,* Claudia Seidenschwarz,
Eberhardt Herdtweck, and Norbert Sewald
Since the formulation of the Woodward-Hoffmann
rules,['] investigation of the mechanisms of cycloaddition
reactions has constituted the central activity of numerous
research groups.[21This area of research has gained enormous impetus through the employment of more reactive
heterodienophile~,[~I
including recently Si=C-sy~tems[~l
and
Si=Si-sy~tems[~,
'I. Alongside the dimethylneopentylsilene
Me,Si=CHCH,tBu investigated by Jones[61we now present
a dichlorinated analog CI,Si=CHCH,tBu 1, which exhibits
a markedly different cycloaddition behavior; this can be attributed to the influence of the chlorine atoms on the position of the frontier orbitals and the magnitude of the orbital
coefficients. The characteristic combination of higher dienophilicity and strongly dipolar Si=C character in the case of
1 ['I manifests itself in its different behavior towards naphthalene 2, which has only slight diene qualities,"' and cyclohexa-1,3-diene 6, which finds frequent use as a [4 21-trapping reagent for heterodien~philes.['~
Reaction of CI,SiCH=CH, with an equimolar amount of
LitBu and excess 2 at 0 "C leads (even in the dark) to formation of the thermally stable endo [4 + 21-cycloadduct 3 in
about 75 % yield (GC integration of the product mixture),
and can be isolated by sublimation at
mbar in ca. 40%
yield. After recrystallization from n-pentane 3 precipitates in
the form of colorless needles, which have been characterized
analytically and NMR spectroscopically.['o1
+
Cl,Si CH=CH2
LitBu
C12Si:CHCH2tBu
3
1
4
5
Reduction of 3 with LiAIH, under mild conditions furnishes crystalline end0-4;'"~ (E)/(z)-isomeric 2,4-dineopentyl-l,3-disilacyclobutane5["1 and 2 are also formed. The
colorless, slightly air-sensitive crystals of 4 are readily soluble in nonpolar solvents and were subjected to an X-ray
structure
Thus, for the first time, it was possible
to determine the structure of a [4 + 2]-cycloadduct of a silene
with naphthalene. Characteristically, the molecule shows
hardly any structural peculiarities compared to the [4+ 21cycloadduct of 1 and anthracene;['' only the C3-C4 bond
length (157.2(1) pm) is significantly longer than the mean
value (2= 152.1 pm) of the other C-C single bonds. Due to
the larger atomic radius of the Si atom the 2-silabicy[*I
[**I
Prof. Dr. N. Auner, Dipl.-Chem. C. Seidenschwarz, Dr. E. Herdtweck,
DipLChem. N. Sewald
Anorganisch-chemisches Institut der Technischen Universitat Miinchen
Lichtenbergstrasse 4, W-8046 Garching (FRG)
Silaheterocycles, Part 10. This work was supported by the VolkswagenStiftung, the Deutsche Forschungsgemeinschaft, and the Fonds der
Cbemischen Industrk-Part 9: [Ill.
OS70-0833/9110404-0444 $3.50
+ ,2510
Angew. Chem. Int. Ed. Engl. 30 (1991) No. 4
clo[2.2.2]octadiene parent compound is slightly distorted in
comparison to the analogous carbon-compound.'' 31 The endo position of the neopentyl group to the ring skeleton in
4tL4]follows from the torsional angles CI-Si-C3-C13
[- 125.7(1)"]and C8-C4-C3-C13 [- 173.7(1)"].
Consistent with theoretical considerations,'' 51 the diene
quality towards 1 increases in the series benzene+
naphthalene +anthracene.@s14,
Formation of the thermodynamically unfavorable endo-product 3 suggests a concerted cycloaddition, especially since we could not trap any
dipolar intermediates during the course of the reaction.
0
P
c1:
(
Fig. 1. Structure of 4 in the crystal (ORTEP at the 50% probability level, the
hydrogens were given an arbitrary radius). Important bond lengths [pm] and
angles ['I: Si-CI 189.7(1), Si-C3 189.3(1), Si-HI 145.0(8), Si-H2 141.6(8), C3C13 154.0(1). C13-Cl4 153.0(1), C3-C4 157.2(1), C4-C5 151.3(1), C5-C6
139.1(1). C b C 6 150.4(1), C1-C7 150.8(1), C7-C8 131.4(1), C4-C8 150.6(1);
Cl-Si-C3 100.29(4), Si-C3-C13 116.45(6), Si-C3-C4 105.87(6), Si-Cl-C6
102.69(5).C6-Cl-C7 109.84(8), C3-C4-C5 108.91(7),C3-C4-C8 107.70(8);C13Si-C3-CI - 125.7(1), C13-C3-C4-C8 - 173.7(1).
+
Even though 6 reacts mainly as a [4 21-trapping reagent,['] the [2 + 21-addition is preferred in the cycloaddition
of 1 with 6. Thus, electrophilic attack of the silene at the
diene leads mainly to regioselective formation of the stereoisomeric (E)/(Z)-silacyclobutane derivative 7. Upon reaction
of the product mixture (7/8) with phenyl-Grignard reagent
only the Si atom in 7 is phenylated, probably on steric
grounds. The cycloadducts 8 and 9 can therefore be separated from each other and be characterized by NMR spectroscopy (NMR data of 7 determined by difference spectrum)."01
7 is obtained in 74% yield (isomeric ratio 7a/7b 62/38) and
8 in 26 YOyield (8a/8 b 63/37). Surprisingly, during storage
(daylight, room temperature) the [ 2 21-cycloadducts 7
transform completely within eight weeks into the thermodynamically more stable bicyclic 2-silaoctenes 8, whose isomer-
+
Cl,Si = CHCH, t8u
+
1
ic ratio remains unaltered; the silacyclobutanes 9, on the
other hand, are stable. Comparative studies on the [2 21cycloadducts 7 and 9 and on the reactivity of the diphenylneopentylsilene confirm that the unusual [2 + 21-cycloaddition of 1 with 6 and the isomerization behavior of 7 are
caused by the influence of the chlorine substituents. Dialkyland diaryl-substituted neopentylsilenes exhibit a markedly
different cycloaddition behavior towards 6.
+
Experimental procedure
3: A stirred mixture of 19 g (148mmol) of 2 and 4.7 g (30 mmol) of
H,C=CHSiCI, in 600 mL ofanhydrous benzene was treated slowly at 0 "C with
21.5 mL (30 mmol) of LitBu; this resulted in elimination of LEI. After filtration and removal of the solvent by distillation, the oily solid residue was freed
of excess 2 by sublimation (40°C/10-z mbar), whereby considerable amounts
of 3 were lost. 3 was initially isolated as a highly viscous, colorless liquid (b.p.
65-70 "C/10-2 mbar); it subsequently crystallized in the receiver (m.p. 70°C).
Yield: 3.72 g, 12 mmol, 40%.
4: A suspension of LiAIH, (0.57 g, 15 mmol) in anhydrous Et,O (40 mL) was
treated dropwise at 0°C with a solution o f 3 (2.0 g, 6.5 mmol) in Et,O (15 mL).
After warming to room temperature the reaction mixture was filtered. Distillation of the solution yielded 4 and 5 at 50"C/10- mbar, while 2 sublimed. After
storage for 3 months at 20°C. 4 crystallized (m.p. 60°C) and was separated
from 5. Yields: 4: 1.04 g (4.29 mmol), 66%; 5 : 0.25 g (1.1 mmol), 34%.
7: A mixture of 7.2 g (90 mmol) of 6 and 4.7 g (30 mmol) of H,C=CHSiCI, in
500mL of n-pentane was treated at -78°C with 21.5 mL LitBu (30mmol;
1.4 mmol/mL n-pentane). The stirred mixture was warmed to room temperature (LiCI precipitation at ca. - 5 T ) , filtered, and the filtrate worked-up by
distillation. 7 and 8 were isolated as colorless, viscous liquids (b.p. 60"Ci
lo-' mbar). Yield 7.82 g, 29.8 mmol, 99.5%.
Received: November 23,1990 [Z 4290 IE]
German version: Angew. Chem. 103 (1991) 425
CAS Registry numbers:
2,91-20-3; 3, 132438-94-9;4, 132438-95-0;(E)-5, 130992-05-1;(Z)-5,13099217-5; 6, 592-57-4; 7a, 132438-96-1; 7b, 132489-62-4; 8a, 132438-97-2; 8b,
132489-63-5; 9a, 132438-98-3; 9b, 132489-64-6; CI,SiCH=CH,, 75-94-5;
Ph,Si=CHCH,tBu, 132439-00-0; endo-2,2-diphenyl-3-(2',2'-dimethylpropyl)2-siIabicyclo[2.2,2]oct-5-ene,132489-65-7; exo-2,2-diphenyl-3-(2',2'-dimethylpropyl)-2-silabicyclo[2.2.2]oct-5-ene,
132438-99-4.
[l] R. B. Woodward, R. Hoffmann: The Conserwalion of Orbital Symmetry,
Verlag Chemie, Weinheim 1970; Angew. Chem. 81 (1969) 797; Angew.
Chem. Int. Ed. Engl. 8 (1969) 781.
[2] J. Sauer, R. Sustmann, Angew. Chem. 92 (1980) 773; Angew. Chem. Int. Ed.
Engl. 19 (1980) 779.
[3] D. L. Boger, S. N. Weinreb: Hetero Diels-Alder Methodology in Organic
Synthesis, Academic Press, London 1987.
[4] For reviews see: N . Wiberg, J. Organomet. Chem. 273 (1984) 141; G.
Raabe, J. Michl, Chem. Rev. 85 (1985) 419.
IS] Review: R. West, Angew. Chem. 99 (1987); 1231; Angew. Chem. Int. Ed.
Engl. 25 (1987) 1201.
[6] P. R. Jones, T. F. 0. Lim, J. Am. Chem. Soc. 99 (1977) 8447; P. R. Jones,
T. F. 0. Lim, R. A. Pierce, ibid. 102 (1980) 4970.
[7] N. Auner, Habilitationsschrift, Miinster, 1987; 2.Anorg. Allg. Chem. S58
(1988) 5 5 ; J. Organomet. Chem. 353 (1988) 275.
(81 Review: J. Sauer, Angew. Chem. 78 (1966) 233; Angew. Chem. Int. Ed.
Engl. 5 (1966) 211.
[9] U. Annen, M. Regitz, TetrahedronLelt. 1988, 1681; J. Grobe, J. Szameitat,
2.Naturforsch. B 43 (1988) 427; C. Larson, D. N. Hopp, J. Org. Chem. 45
(1980) 3713; E. Kessler, J. Heterocycl. Chem. 17(1980) 1113; K. Friedrich,
H.-J. Gallmeier, Tetrahedron Lett. 2981, 2971 ; reaction of tBu,Si=SirBu,
with 6, however, leads to the [2 21-adduct: M. Weidenbruch, A. Schafer.
K.-L. Thorn, Z . Naturforsch. B 38 (1983) 1695.
[lo] The compounds 3-5 and 7-9 were characterized by elemental analysis
(C,H,Si) and mass spectroscopically (70 eV). Their 'H- and I3C-NMR
parameters were determined by H,H-, C,H-COSY and -NOESY investigations. In addition to the Z9Si-NMRvalues the data sets for 4 and 7a are
given. 4: 'H NMR (360 MHz, CDCI,, 25°C. TMS, J(H,H) in Hz): 6 =
7.22-7.12 (m. 4 H aromat.), 6.38 (ddd, ' J =7.9,6.6, 4J = 1.2,l H olefin.),
6.32 (dddd, 3J =7.9,6.3, 4J = 1.2.0.8, 1 H olefin.), 3.83 (m.1 H, H4), 3.81
(m,1H,SiH,),3.80(m,lH,Hl),3.27(dd,broad,zJ=14.0,3JJ=
1.5,lH.
SiH,), 1.30-0.85 (m, 3H, H3, H9), 0.87 (s, 9H, tBu); "C NMR
(90.6 MHz, CDCI,, TMS, DEPT, C,H-COSY [with f,-decoupling: 200 x
2 K FIDs, zero filling to 512 x 2 K, apodized (improvement of resolution)
with sinus function]): 6 = 140.10,139.64 (C aromat.); 132.39,130.66 (CH
olefin.); 125.93, 125.77, 124.52, 123.73 (CH aromat.); 48.24 (C4). 46.79
+
7a
7b
8a
8a
9a
8b
+
9b
Angew. Chem. lnt. Ed. Engl. 30 (1991) No. 4
0 VCH
8b
Verlagsgesellschaft mbH. W-6940 Weinheim. 1991
0570-0833/9l/0404-0445 $3.50+ .25/0
445
(C9). 31.78 (Cl), 31.41 (C(CH,),), 29.79 (C(CH,),), 19.49 (C3); 29SiNMR (79.4 MHz, CDCI,, TMS): 6 = - 30.4 (t), 1J(29Si1H)= 204 Hz;
IR: v[cm-'] = 2145 (SiH); UV: I,,,[nm] = 268.2, 274.2. 7a: 'H NMR:
6 = 2.49 (m, 1 H, Hl), 5.91 (m, 1 H, H2), 5.74 (m, 1 H, H3), 1.94 (m, 1 H,
H,4), 2.05 (m, 1H, Hb4), 1.78 (m. 1 H, H,5), 1.96 (m. 1 H, Hb5), 2.21 (m,
l H , H6), 2.01 (m, l H , HS), 1.49, 1.71 (m, 2H, H9), 0.77 (s, 9H, tBu);
I3CNMR: 6 = 38.42 (Cl), 130.27 (C2), 126.00 (C3). 23.84 (C4), 20.01
(C5), 35.52(C6),44.58 (C8),43.14(C9), 31.08 (C(CH,),), 29.55(C(CH3),).
"Si NMR: 6 = 15.8 (3), 19.7 (7a), 14.2 (7b), 25.6 (8a), 26.5 (8b).
[ll] N. Auner, R. Gleixner, JI Organomet. Chem. 393 (1990) 33.
[12] P. Kiprof, E. Herdtweck, R. E. Schmidt, M. Birkhan, W. Massa: STRUX111 (Programmsystem zur Verarbeitung von Rontgendaten, Technische
Universitat Munchen/Universitat Marburg, 198911985), Compound 4
crystallizes from n-pentane as colorless rods, monoclinic space group P2,/
c. a = 1502.9(1), b = 860.4(1), c = 1182.7(1) pm, fl = 106.80(2)", V =
1464 x lo6 pm3, C,,H,,Si, M = 242.4, Z = 4, q,,,, = 528, eCmlGd
=
1.100 g cm-,; apparatus: Enraf-Nonius CAD-4, Cu,, radiation (1=
154.184 pm). graphite monochromator, T = 21 f 1 "C; range of measurement: 1.0" < 0 < 65.0, 8/20 scan. 5604 measure reflections ( f h.k.1, each
at @ = 0" and 3") were determined after LP correction and correction for
a slight distortion (376 cancelled reflections and 278 with I < 0 were considered as unobserved). No absorption correction ( p = 12.0 cm-'). All
2425 independent reflections ( I > 0) were refined with 243 parameters
using full matrix least squares. R = 0.043, R, = 0.038, GOF = 3.732
(p = 0.00) with w = l/a'(F,). Solution of structure by direct methods and
were
difference Fourier technique. Extinction effects ( E = 0.1995 x
corrected. All hydrogen atom positions are successively taken from difference Fourier syntheses and refined with isotropic temperature factors.
Anomalous dispersion is taken into account. After the last refinement
cycle (shiftierror < 0.00) the maximal/minimal residual electron density
contributed 0.191- 0.29 eo-/A3. Further details of the crystal structure
investigation are available on request from the Fachinformationszentrum
Karlsruhe, Gesellschaft fur wissenschaftlich-technischeInformation mbH,
W-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository
number CSD-54651, the names of the authors, and the journal citation.
[13] To our knowledge no solid-state structure has been published for the
parent compound bicyclo[2.2.2]octadiene.For a structural comparison see
D. Dopp, C. Kruger, H. R. Memarian, Y-H. Tsay, Angew. Chem. 97
(1985) 1059; Angew. Chem. Int. Ed. Engl. 24 (1985) 1048; B. Karlsson,
A.-M. Pilotti, A.-C. Soderholm, Acta Chem. Scand. Ser. B 31 (1977) 619;
P. Argos, R. Clayton, Acla Crystallogr. Sect. B 29 (1973) 910; S. Hechtfischer, W. Steigemann, W. Hoppe, Acra Crystallogr. Sect. B 26 (1970)
1713.
[14] In the meantime endo/exo-[2,2-diphenyl-3-(2',2'-dimethylpropyl)-2-silabicyclo[2.2.2]oct-5-ene]has been synthesized by [4 21-cycloaddition from
Ph,Si=CHCH,IBu and 6 and was characterized analytically and mass
spectroscopically by us. The isomeric ratio of 70/30 was demonstrated by
GC and NMR studies in solution and by X-ray structure analysis in the
crystalline state: N. Auner, W. Ziche, E. Herdtweck, unpublished results.
[l5] A. Streitwieser: Molecular Orbilal Theory for Organic Chemists, Wiley,
New York 1961, p. 432.
[16] N. Auner, J. Organomer. Chem. 377 (1989) 175.
+
+
13C-NMR spectra and theoretical calculations indicated
that 2a (three-membered ring) and 671 (five-membered ring)
electron conjugations, due to polarization of each calicene
unit, significantly contribute to the electronic structure in the
ground state.[31This polarization could also be favored by
the avoidance of an antiaromatic 16n electron conjugation in
the periphery. In the next higher homologue, tercalicene 2 a,
however, an aromatic 22 n electron conjugation could be
present, whereas quatercalicene 3a adopts a similar R electron conjugation mode to that of 1 a because of the presence
of 28 a electrons in the periphery. We report here on the
synthesis of 2a and the 3, 10- and 3,17-bis(tert-butylthio)
derivatives 2 b and 3 b, respectively, and discuss the possible
electronic structures of 2a and 3a based on the molecular
structure of 2b, and the 'H- and 13C-NMRspectral data for
2a, 2b and 3b.
l a : X=Y=H
2% X=Y=H
3a:X=Y=H
1b: X=Y=S t Bu
2b: X=Y=SfBu
2c: X=Y=SnnBu
3b: X=Y=S tBu
3c: X=Y=SnnBu
2 b and 3 b were synthesized from 1 b as shown in Scheme
1, and converted in a two-step process-distannylation and
acid- or base-catalyzed hydrolysis-into 2 a and 3 a.
Thus, the 3,1l-bis(tert-butylthio)derivative 1b[2b1was allowed to react with lithium cyclopentadienide (20 equiv.) in
THF at 0°C to give the central intermediate 4 (yield 82%,
Table 1). By successive reaction of 4 with lithium diisopropylamide (LDA) (2 equiv.) and 1,2-bis(tert-butylthio)-3,3-
l)LOA, THF
lb
THF
-
2b
tBuS
4
1)LDA
/
Tercalicene and Quatercalicene
By Toyonari Sugimoto,* Mitsuhiro Shibata, Akihiko Sakai,
Hiroshi Ando, Yoshihisa Arai, Masashi Sakaguchi,
Zen-ichi Yoshida,* Yasushi Kai,* Nobuko Kanehisa,
and Nobutami Kasai*
In contrast to calicene,"] which still remains a synthetic
challenge, bicalicene 1 a, which is composed of two calicene
units in a head-to-tail orientation, was already prepared by
us a few years ago.[2]An X-ray structural analysis, 'H- and
[*I Prof. Dr. T. Sugimoto, Prof. Dr. Z. Yoshida, Dr. M. Shibata, A . Sakai,
H. Ando, Y. Arai, M. Sakaguchi
Department of Synthetic Chemistry
Kyoto University
Yoshida, Kyoto 606 (Japan)
Prof. Dr. Y Kai, Prof. Dr. N. Kasai, N. Kanehisa
Department of Applied Chemistry
Osaka University,
Yamadaoka, Osaka 565 (Japan)
446
0 VCH Verlagsgesellschafr mbH, W-6940 Weinheim, 1991
2b
InBu)3SnH.AIBN
c
C,H,CI.
2c
115OC. 5-10 rnin
inBu),SnH. AlBN
AcOH
2a
C,H6/MeOH
11:1).ca.20°C
AcOH o r
NaOMe
C,H,/MeOH
(1: l).ca.20°C
* 3c
3b
C,H,CI.115°C.5-10
rnin
-
Scheme 1.
OS70-0833/91/0404-0446 $3.SOf .2S/O
Angew. Chem. Inr. Ed. Engl. 30 (1991) N o . 4
3a
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dieneцsilene, naphthalene, cyclohexyl, novem, cycloadducts
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