En route to 7,7,8,8-tetraethynyl-p-quinodimethane (TEQ)

Article abstract of DOI:10.1002/1099-0690(200205)2002:10<1708::AID-EJOC1708>3.0.CO;2-A

The cross-conjugated 1,1-diethynylethylene derivatives 8b-10b were prepared from the corresponding bromides 16, 19, and 17 by Sonogashira coupling with trimethylsilylethyne and hydrolysis of the TMS-protected intermediates thus formed. Coupling of the tetrabromide 18 with (trimethylsilylethynyl)magnesium bromide in the presence of 1,3-[bis(diphenylphosphanyl)propane] nickel(II) chloride yielded the protected tetraalkyne 32, from which the 7,7,8,8-tetraethynyl-tetrahydro-p-quinodimethane 33 was liberated by fluoride treatment. Although 33 is a highly unstable cross-conjugated hydrocarbon, it could be converted into its tetraphenyl derivative by Sonogashira coupling with phenyl iodide. Both 32 and the corresponding tetraphenyl derivative were oxidized to the 7,7,8,8-tetraethynyl-dihydro-p-quinodimethane derivatives 35 and 36, respectively, on treatment with DDQ in dioxane. Further dehydrogenation of 35 to 34 failed, however. Alkylation of 9b with trimethylaluminium in the presence of zirconocene dichloride as catalyst yielded the semicyclic dendralene 37, which on irradiation isomerized to the tricyclic diene 42, presumably via the bicyclobutane 39 and a vinylcyclopropane rearrangement. Hydration of 9b furnished 43 and 44, the primary hydration product 38 either undergoing ketene elimination (formation of 43) or a 1,5-hydrogen shift reaction (to 44) from its tautomer 41. Analogously, the still more highly unsaturated derivative 31 was alkylated to give the [5]dendralene derivative 45 and hydrated to give a mixture of the β-diketones 46 and 49, the latter being produced from 46 by 1,2-methyl migration. The thermal cyclization of 10b to the homoacepentalene derivative 51 failed. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0690(200205)2002:10<1708::AID-EJOC1708>3.0.CO;2-A

FULL PAPER
En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane (TEQ)[‡]
Henning Hopf,*[a] Jan Kämpen,[a] Peter Bubenitschek,[a] and Peter G. Jones[b]
Dedicated to Professor Lutz F. Tietze on the occasion of his 60th birthday
Keywords: Alkynes / Dendralenes / Isomerization / Photochemistry / Polycycles / Sonogashira coupling
The cross-conjugated 1,1-diethynylethylene derivatives
ever. Alkylation of 9b with trimethylaluminium in the pres-
8b−10b were prepared from the corresponding bromides 16,
ence of zirconocene dichloride as catalyst yielded the semi-
19, and 17 by Sonogashira coupling with trimethylsilylethyne cyclic dendralene 37, which on irradiation isomerized to the
and hydrolysis of the TMS-protected intermediates thus
formed. Coupling of the tetrabromide 18 with (trimethylsilyl-
ethynyl)magnesium bromide in the presence of 1,3-[bis(di-
tricyclic diene 42, presumably via the bicyclobutane 39 and
a vinylcyclopropane rearrangement. Hydration of 9b fur-
nished 43 and 44, the primary hydration product 38 either
phenylphosphanyl)propane]nickel(II) chloride yielded the undergoing ketene elimination (formation of 43) or a 1,5-hy-
protected tetraalkyne 32, from which the 7,7,8,8-tetraethy-
nyl-tetrahydro-p-quinodimethane 33 was liberated by fluor-
ide treatment. Although 33 is a highly unstable cross-conjug-
ated hydrocarbon, it could be converted into its tetraphenyl
derivative by Sonogashira coupling with phenyl iodide. Both
32 and the corresponding tetraphenyl derivative were oxid-
ized to the 7,7,8,8-tetraethynyl-dihydro-p-quinodimethane
derivatives 35 and 36, respectively, on treatment with DDQ
in dioxane. Further dehydrogenation of 35 to 34 failed, how-
drogen shift reaction (to 44) from its tautomer 41. Analog-
ously, the still more highly unsaturated derivative 31 was al-
kylated to give the [5]dendralene derivative 45 and hydrated
to give a mixture of the β-diketones 46 and 49, the latter be-
ing produced from 46 by 1,2-methyl migration. The thermal
cyclization of 10b to the homoacepentalene derivative 51
failed.
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
Introduction
all-carbon parent systems of these strong electron acceptors
are tetraethynylethene (TEE, 3,4-diethynylhex-3-ene-1,5-di-
yne, 2) and 7,7,8,8-tetraethynyl-p-quinodimethane (TEQ,
4, Scheme 1).
Tetracyanoethylene (TCNE, 1), prepared in 1957 by du
Pont chemists,[2] was the first example of a percyanoolefin
and quickly gained importance in preparative and mechan-
istic chemistry because of its high reactivity in addition and
substitution reactions[3] and its ability to form charge-trans-
fer complexes,[4] to name but a few of its numerous applica-
tions.[5] Only a few years later, another polycyano-substi-
tuted compound also destined to have a lasting influence
on organic chemistry, 7,7,8,8-tetracyano-p-quinodimethane
(TCNQ, 3), was described.[6] This bis(vinylogous) derivative
of 1 became prominent in particular for the preparation of
highly conducting charge-transfer salts such as the
tetrathiafulvaleneϪTCNQ complex,[7] thus contributing to
the still intensely studied area of ‘‘organic metals’’.[8] The
[‡]
New Planar π-Systems, VI. Part V: Ref.[1a]
[a]
Institut für Organische Chemie, Technische Universität
Braunschweig,
Scheme 1. A selection of important cross-conjugated systems
Hagenring 30, 38106 Braunschweig, Germany
Fax: (internat.) ϩ 49-(0)531/391-5388
E-mail: h.hopf@tu-bs.de
[b]
Whereas compound 2, interest in which goes back to the
late 1960s,[9] was finally synthesized by Diederich and co-
workers in 1991,[10] the preparation of 4 has to the best of
our knowledge[11] not so far been described. TEE and its
Institut für Anorganische und Analytische Chemie, Technische
Universität Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Fax: (internat.) ϩ 49-(0)531/391-5387
E-mail: jones@xray36.anchem.nat.tu-bs.de
1708
 WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ193X/02/0510Ϫ1708 $ 20.00ϩ.50/0 Eur. J. Org. Chem. 2002, 1708Ϫ1721

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
FULL PAPER
derivatives have proven to be most interesting π-systems for pare model compounds of types 8Ϫ10, since we anticipated
the construction of very large extended conjugated struc- that these would be useful for spectral and chemical com-
tures that show promise for applications in material sci- parison. We were, in particular, interested in the gem-di-
ence.[12] In this publication we describe our first efforts to methyl-protected
cross-conjugated[16]
hydrocarbons
prepare derivatives of and precursors for 4. As will be 8bϪ10b; the parent systems 8aϪ10a would be expected to
shown, the most highly unsaturated derivatives of TEQ that show an increasing tendency to aromatize: 3-methylene-1,4-
we have so far been able to prepare are dihydro derivatives cyclohexadiene (‘‘isotoluene‘‘), the parent hydrocarbon of
of the tetraphenyl- and tetrakis(trimethylsilyl)-protected 10a, has long been known to isomerize rapidly to toluene
compounds.
under various conditions.[17]
The monoketones 13؊15, the starting materials for most
of the cross-conjugated derivatives described in this study,
are easily available by known methods. Thus, Robinson an-
nelation of methyl vinyl ketone (11) with 2-methylpropanal
(12) furnished 4,4-dimethylcyclohex-2-enone (13).[18] This
was hydrogenated to the saturated ketone 14 in the presence
of palladium on carbon[19] and oxidized to 15 by DDQ
treatment,[20] the yields being acceptable in all cases
(Scheme 3).
Results and Discussion
Preparation of Model Compounds and of Di- and
Tetrahydro-TEQs
From the retrosynthetic viewpoint, promising starting
materials for 4 offer themselves in the forms of the tetra-
halo-p-xylylenes 5b[13] and 5c,[14] which Ϫ like their tetra-
fluoro analogue 5a[15] Ϫ have been described several times
in the literature. However, since we feared that their high
reactivity, which results in dimerization (formation of
[2.2]paracyclophane derivatives) and polymerization (pro-
duction of halogenated ‘‘parylenes‘‘), would interfere with
the intended coupling reactions of these substrates with
various (protected) acetylenes, we initially decided to aim
for a lesser goal: the tetrahalides 7 (Scheme 2), obtainable
from the commercial product 1,4-cyclohexanedione (6).
Scheme 3. Preparation of starting materials for cross-conjugated
enynes
The next steps, affording the dihalides 16 and 17 and the
tetrahalide 18, were also routine. The reliable tetrabromo-
methane/triphenylphosphane method was employed for di-
bromoolefination of ketones,[21] and was also used to con-
vert 13 into the dibromide 19. Likewise, 13؊15 were trans-
formed into the dichlorides 20؊22 by use of tetrachlorome-
thane in place of its bromo analogue (Scheme 4).
Scheme 2. Retrosynthesis of tetraethynyl-p-quinodimethane
In the semicyclic diene 7, the two reactive parts are isol-
The first coupling reactions were carried out with phenyl-
ated from each other by ethano groups, which should read- acetylene, by use of the Sonogashira reaction. As expected,
ily allow independent acetylene coupling. In the resulting the ring-saturated dibromide 16 furnished the monoene 23
tetraalkynes, the two missing double bonds should finally (25% yield), while 19 and 17 provided 24 and 25 (30% in
be introducible by dehydrogenation. We also decided to pre- each case). Whereas 24 was isolated as a yellow oil, the
Eur. J. Org. Chem. 2002, 1708Ϫ1721
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H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
Scheme 4. Additional dihalo olefins
more symmetrical products 23 and 25 were yellow, air- and
light-stable solids. The structures of these hydrocarbons
were determined by the usual spectroscopic methods (see
Exp. Sect. for details), the UV/Vis spectra showing the ex-
pected bathochromic shifts on proceeding towards higher
unsaturation; the absorption maxima were recorded (n-
pentane) at 276 nm for 23 and at 332 and 356 nm for 24
and 25, respectively (Scheme 5). On recrystallization from
pentane the cross-conjugated derivative 25 provided single
crystals suitable for X-ray structural analysis. As the results
in Figure 1 show, the molecule displays no imposed sym-
metry. The central portion of the molecule (C3, C7ϪC11,
˚
C20) is planar to within 0.02 A; the cyclohexadiene ring
makes an angle of only 7° to this plane, and the phenyl
ring C20Ϫ25 is inclined to it by only 18°; the ring C14Ϫ19,
however, is almost perpendicular to it (79°). Most bond
lengths and angles may be regarded as normal, but there
are some perturbations in the region of the central C3ϭC7
˚
double bond. This bond itself is rather long at 1.370(2) A,
which may be associated with some delocalization (cf.
Figure 1. The structures of 25 and 31 in the crystal
˚
C2ϪC3 and C3ϪC4 ca. 1.45 A), and the angles
C8ϪC7ϪC10 and C2ϪC3ϪC4 are narrow at 115.84(12)
and 116.33(12)°. In the cyclohexadiene ring, the angles at
C2 and C4 (ca. 122°) and C1 and C5 (ca. 124.5°) are
widened to compensate for the narrow angle at the sp3-hy-
bridized C6.
These coupling processes take place stepwise via the cor-
responding monobromides; in fact, when the amount of
phenylacetylene was reduced in the case of 19, the mono-
substitution product 26 was obtained in 50% yield. Interest-
ingly, the process took place with high diastereoselectivity
to afford only the (E) isomer of 26, as was shown by NMR
spectroscopy including NOE experiments (Scheme 5). The
monobromides 27 (50%) and 28 (35%) were prepared ana-
logously, from 16 and 17, respectively. The oily vinyl brom-
Scheme 5. Preparation of phenyl-substituted cross-conjugated
enynes
1710
Eur. J. Org. Chem. 2002, 1708Ϫ1721

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
FULL PAPER
ides 26؊28 were stable in solution for several weeks and are
Having established the basic synthetic operations re-
of potential value as coupling partners for the preparation quired in this area, the more demanding goal of preparing
of other extended cross-conjugated enynes by, inter alia, TEQ precursors or derivatives was addressed next. Surpris-
dimerization.
ingly, Sonogashira coupling of the tetrabromide 18 either
In the next series of experiments, trimethylsilylacetylene with phenylacetylene or with trimethylsilylacetylene failed
was used as the coupling partner in order to provide a pro- under the above conditions, without even partially substi-
tective group that could be removed after successful Sono- tuted derivatives being formed. Fortunately, however, Kum-
gashira coupling. The expected products 29Ϫ31 (Scheme 6) ada coupling of (trimethylsilylethynyl)magnesium bromide
were all obtained in acceptable yields (50, 55, and 65%, re- in tetrahydrofuran in the presence of 1,3-[bis(diphenylphos-
spectively). Again, the less symmetrical diyne 30 was an oil, phanyl)propane]nickel(II) chloride [(dppp)NiCl2] was suc-
whereas the other two compounds crystallized as yellow cessful,[23] yielding 32 in 50% yield. This tetrahydro-TEQ
needles. The molecular structure of 31 was determined by derivative was an intensely yellow solid, displaying fluores-
X-ray diffraction and the result is also reproduced in Fig- cence in pentane solution. It was recrystallized from dichlo-
ure 1. The atoms C1Ϫ11 are coplanar (mean deviation 0.02 romethane to provide single crystals of X-ray quality, and
˚
A), and the dimensions of the same moiety are very similar the result of the diffraction experiments is shown in Fig-
to those of the analogous portion of 25.
ure 2. The molecule displays crystallographic inversion sym-
metry. The atoms C1Ϫ8 are coplanar (mean deviation 0.03
˚
˚
A). The central double bond C2ϭC4, at 1.348(4) A, is of a
normal length because the saturated ring precludes delocal-
ization of the form seen in 25 and 31. The angle
C5ϪC4ϪC7 is still narrow at 117.1(2)°, which seems to be
a general feature of the CϭC(CϵC)2 moiety.
Desilylation of 32 to 7,7,8,8-tetraethynyl-tetrahydro-p-
quinodimethane (33) initially met with considerable diffi-
culties. Deprotection under the above conditions (meth-
anolic KOH solution) failed completely, with 32 being reco-
vered quantitatively even after stirring for several hours at
room temperature. On the other hand, when 32 was treated
with tetrabutylammonium fluoride (TBAF) in moist tetra-
hydrofuran, the reaction mixture immediately turned black,
and no products soluble either in pentane or in dichlorome-
thane were obtained. However, when this homogenous re-
action system was replaced by a vigorously stirred two-
phase system, consisting of an aqueous TBAF solution co-
vered by a pentane layer, 33 was generated from its trime-
thylsilyl-protected precursor in ca. 75% yield. The red solid
polymerized within hours at room temperature, but was
stable enough to be employed for further transformations
(see below). On heating of a dioxane solution of 32 under
Scheme 6. Preparation of the parent systems 8bϪ10b
Varying amounts of the dimer of the acetylenic partner reflux in the presence of a fourfold excess of 2,3-dichloro-
were produced in all coupling experiments, presumably by 5,6-dicyano-p-benzoquinone (DDQ), dehydrogenation took
reductive elimination of an intermediately formed dialkyn- place to furnish the dihydro-TEQ derivative 35 in 20%
ylpalladium(II) complex, a phenomenon often observed in yield. Unfortunately, all attempts to oxidize this orange-
these metal-mediated processes.[22]
colored solid further to 34 have so far failed. When the
For deprotection, the trimethylsilyl derivatives were amount of oxidant or the reaction conditions were varied,
stirred in methanolic KOH solution at room temperature; only a black material that could not be characterized by
the hydrocarbons 8b, 9b, and 10b were all formed in high physical or chemical methods was obtained in all cases
yields (90%). Although all of them were unstable Ϫ show- (Scheme 7).
ing strong tendencies to polymerize during workup and
Since we expected that phenyl substituents in place of the
handling Ϫ their structures could be assigned unambigu- TMS groups would exert a stabilizing influence on TEQ,
ously by spectroscopy (see Exp. Sect.). The absorption max- we prepared the tetraphenyl derivative of 33 by subjecting
ima in their electronic spectra (in n-pentane) shifted from the tetraacetylene (liberated in situ) to Sonogashira coup-
252 nm for 8b through 292 nm for 9b to 340 nm for 10b, ling with iodobenzene. The desired hydrocarbon, a stable,
the last member of the series. Although 8b was isolated as orange solid, was obtained in good yield (75%). However,
a low-melting solid (m.p. 54 °C), we were unable to obtain its dehydrogenation with excess DDQ again stopped at the
crystals suitable for X-ray diffraction. Compounds 9b and dihydro-TEQ stage, yielding the cross-conjugated derivative
10b were isolated as red oils, the latter possibly being 36 in 20% yield. The orange hydrocarbon could be stored
noncrystalline because of impurities.
in the cold for several weeks before decomposition set in,
Eur. J. Org. Chem. 2002, 1708Ϫ1721
1711

H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
Figure 2. The structure of 32 in the crystal
mon intermediate for both 43 and 44. To arrive at the for-
mer, 41 could lose ketene by the fragmentation process sym-
bolized by the dotted arrows in Scheme 8; the resulting al-
lenol 40 would subsequently tautomerize to (E)-/(Z)-43. To
arrive at 44, intermediate 41 would have to undergo a 1,5-
Scheme 7. En route to tetraethynyl-p-quinodimethane derivatives
accompanied by a color change to black. Interestingly, (E)-
7,8-diphenyl-para-quinodimethane has been obtained from
its tetrahydro precursor by DDQ treatment in benzene.[24]
In order to gain an initial impression of the chemical be-
havior of some of the novel cross-conjugated systems pre-
pared in this study, we selected the two derivatives 9b and
31 as model compounds (Schemes 8, 9). When 9b was hy-
drated in the presence of mercury(II) sulfate and sulfuric
acid in methanol, the expected diketone 38 was not ob-
tained, but rather a product mixture consisting of an isomer
of 38, the acetylacetone derivative 44 (35% yield) and the
unsaturated monoketones 43 [yield 10%; (Z)-43: 67%, (E)-
43: 33%]. We assume that the enol 41, the immediate pre-
cursor of 38 during the hydration process, serves as a com- Scheme 8. The chemical behavior of 9b
1712 Eur. J. Org. Chem. 2002, 1708Ϫ1721

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
FULL PAPER
hydrogen shift, by which one of the hydrogen atoms of the with the resonance structure of 46 Ϫ structure 47 Ϫ
(activated) ring methylene group would be transferred to whereby the intermediate 48 thus generated rearomatizes to
the double bond of the enol (full arrows in 41).
49 by proton transfer (Scheme 9). Since 46 does not possess
Carbalumination of 9b with trimethylaluminium in the activated methylene groups in its six-membered ring, no
presence of Cp2ZrCl2 as catalyst in moist dichloromethane process similar to the 41Ǟ44 isomerization is possible.
according to a procedure reported by Wipf and Lim[25] fur-
The photochemical and thermal isomerization behavior
nished the dendralene 37 in excellent yield (90%) as a yellow of 10b turned out to be disappointing. Under a variety of
oil. When this hydrocarbon was irradiated with a low-pres- conditions (irradiation with a 15-W low-pressure mercury
sure mercury lamp in pentane in a falling film apparatus at lamp in a falling film apparatus at different concentrations
256 nm, photoisomerization occurred, resulting in at least and reactions times), only polymeric material was obtained
five photoproducts. The main product from the photolysate when the hydrocarbon was irradiated. Under flash vacuum
(50% by GC analysis) could be isolated by silica gel chro- conditions, no isomerization took place below 700 °C, and
matography; according to its spectroscopic data (see Exp. when the diacetylene was subjected to still harsher pyrolysis
Sect.) it had the bizarre structure 42. Nevertheless, a rela- conditions only fragmentation to benzene, toluene, and the
tively simple pathway for its formation suggests itself. In the xylenes was detected. The intended thermal isomerization
first step, the sterically fixed butadiene subsystem of 37 product, the homoacepentalene derivative 51, which in
ring-closes to the bicyclobutane derivative 39, in analogy to principle could be generated via vinylidenecarbene pre-
the classical examples from the steroid field studied by cursors, as summarized in structure 50, was not observed.
Dauben and co-workers.[26] Intermediate 39, being a
strained vinylcyclopropane, can undergo the corresponding
Experimental Section
isomerization to yield the ultimately isolated rearrangement
product 42. This still contains a vinylcyclopropane subunit
that could isomerize further to provide one of the other,
unidentified photoproducts.
When the isotoluene derivative 31 was initially desilylated
to 10b, which was methylated in situ with trimethylalumin-
ium as described above, the tetravinylethene derivative 45
was generated, the yield again being very good at ca. 90%
over both steps. In contrast to 9b, deprotection of 31 fol-
lowed by HgSO4-catalyzed hydration allowed the isolation
of the diketone 46 in 40% yield. As a second major product
(30%), the β-diketone 49 was produced, its formation obvi-
ously requiring a 1,2-methyl migration step. This could start
General Remarks, Instrumentation: All solvents and starting mat-
erials employed were purified and dried according to standard pro-
cedures; experiments in anhydrous solvents were carried out under
nitrogen. NMR: Bruker AC 200 F (200 MHz) and AM 400
(400 MHz) in CDCl3 and [D6]acetone, TMS as internal standard.
13C NMR spectra are 1H broad-band decoupled; multiplicities were
determined by the DEPT technique. Signals marked with an aster-
isk are ambiguous and possibly interchangeable. IR: Nicolet DX
320 FT-IR spectrometer. UV/Vis: HP 8452 diode array spectro-
meter. GC/IR: Carlo Erba HRGC 5160 with a quartz capillary
column (30 m DB 1, 100% dimethylpolysilicone) coupled to a Nic-
olet SX 740 FT-IR spectrometer. MS (EI): Finnigan MAT 8430,
at 70 eV. GC/MS: Carlo Erba HRGC 5160 with a quartz capillary
column (30 m DB 1, 100% dimethylpolysilicone) coupled to Finni-
gan 4515, EI at 40 eV.
4,4-Dimethylcyclohex-2-en-1-one (13): Freshly distilled methyl vinyl
ketone (11, 70.1 g, 82.5 mL, 1.0 mol) was dissolved in 2-methylpro-
panal (12, 108.2 g, 137.0 mL, 1.5 mol) and concd. sulfuric acid
(1 mL) was added to the mixture. The solution was carefully
warmed to 45Ϫ50 °C, and when the exothermic reaction had
started the internal temperature was kept at ca. 50 °C by external
cooling. When the mixture had reached room temp. again, the
water produced during the condensation was removed and the re-
maining oil was vacuum-distilled (b.p. 55 °C/8 Torr) to yield 13
(80.7 g, 65%) as a colorless oil. Although the ketone has been de-
scribed in the literature,[18] its analytical data are incomplete. 1H
NMR (400 MHz, CDCl3): δ ϭ 1.17 (s, 6 H, 7-H/8-H), 1.87 (ps-t,
3
3
2 H, J5-H,6-H ϭ 6.9 Hz, 5-H), 2.46 (ps-t, 2 H, J5-H,6-H ϭ 6.9 Hz,
3
3
6-H), 5.83 (d, J2-H,3-H ϭ 10.2 Hz, 1 H, 2-H), 6.66 (d, J2-H,3-H
ϭ
10.2 Hz, 1 H, 3-H). 13C NMR (100 MHz, CDCl3): δ ϭ 27.7 (C-7/
C-8), 32.8 (C-4), 34.4 (C-6), 36.1 (C-5), 126.8 (C-2), 159.5 (C-3),
199.5 (C-1). IR (film): ν˜ ϭ 3022 cmϪ1 (w), 2961 (s), 2930 (m), 2869
(m), 1683 (s), 1621 (w), 1471 (w), 1376 (m), 1236 (m), 1203 (w),
1122 (m), 1029 (w), 804 (m). UV (CH3OH): λmax (lg ε) ϭ 226 nm
(4.02). GC/MS (EI): m/z (%) ϭ 124 (47) [Mϩ], 109 (8), 96 (80), 95
(13), 82 (100), 81 (75), 79 (17), 68 (33), 67 (54), 55 (13), 53 (28),
41 (29).
4,4-Dimethylcyclohexan-1-one (14): A solution of 13 (5.3 mL,
Scheme 9. The chemical behavior of 31
Eur. J. Org. Chem. 2002, 1708Ϫ1721
40 mmol) in anhydrous diethyl ether (70 mL) was hydrogenated in
1713

H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
the presence of Pd/C (0.5 g) at room temp. The catalyst was re-
moved by filtration and the solvent was evaporated under vacuum.
Chromatography on silica gel with pentane/diethyl ether (2:1) fur-
nished 14 (4.3 g, 85%) as colorless needles, m.p. 41Ϫ42 °C. Al-
though the ketone has been described in the literature,[19] its analyt-
phenylphosphane (26.2 g, 0.1 mol) and tetrabromomethane (16.6 g,
0.05 mol) in anhydrous toluene (125 ml). The reaction mixture was
heated at 85 °C for 18 h and the solid components were removed
by filtration. After these had been washed carefully with pentane,
the organic phases were combined and dried (MgSO4), and the
ical data are incomplete. 1H NMR (400 MHz, CDCl3): δ ϭ 1.11 solvents were removed in vacuo. Column chromatography (silica
3
3
(s, 6 H, 7-H/8-H), 1.67 (t, J2-H,3-H ϭ J5-H,6-H ϭ 7.0 Hz, 4 H, 3-
gel, pentane) provided 17 (3.1 g, 45%) as a yellow oil, which quickly
3
3
1
H/5-H), 2.32 (t, J2-H,3-H ϭ J5-H,6-H ϭ 7.0 Hz, 4 H, 2-H/6-H). 13C decomposed (even in solution). H NMR (400 MHz, CDCl3): δ ϭ
3
3
NMR (100 MHz, CDCl3): δ ϭ 26.9 (C-7/C-8), 29.2 (C-4), 37.3 (C-
1.11 (s, 6 H, 8-H/9-H), 5.86 (ps-d, J1-H,2-H ϭ J4-H,5-H ϭ 10.2 Hz,
2/C-6), 38.5 (C-3/C-5), 210.9 (C-1). IR (KBr): ν˜ ϭ 2951 cmϪ1 (s),
2 H, 1-H/5-H), 6.48 (ps-d, J1-H,2-H ϭ J4-H,5-H ϭ 10.2 Hz, 2 H, 2-
3
3
2927 (m), 2911 (m), 2864 (m), 1706 (s), 1676 (w), 1474 (w), 1459 H/4-H). 13C NMR (100 MHz, CDCl3): δ ϭ 28.5 (C-8/C-9), 36.8
(w), 1234 (w), 1145 (m). UV (CH3OH): end absorption. GC/MS (C-6), 90.4 (C-7), 121.9 (C-2/C-4), 133.7 (C-3), 141.5 (C-1/C-5). IR
(EI): m/z (%) ϭ 126 (47) [Mϩ], 111 (16), 97 (8), 83 (13), 71 (100), (film): ν˜ ϭ 3039 cmϪ1 (w), 2961 (m), 2921 (m), 2866 (w), 1652 (w),
70 (52), 69 (29), 57 (35), 56 (43), 55 (86), 53 (10), 43 (89), 42 (14),
41 (57).
1533 (w), 1470 (m), 1267 (w), 925 (m), 844 (m), 812 (s), 795 (s),
661 (m). UV/Vis (n-C5H12): λmax (lg ε) ϭ 268 nm (sh, 4.41), 274
(4.43). GC/MS (EI): m/z (%) ϭ 280 (14) [Mϩ], 278 (22) [Mϩ], 276
(10) [Mϩ], 265 (53), 263 (100), 261 (50), 199 (46), 197 (40), 184
(24), 182 (18), 117 (29), 103 (85), 91 (26), 77 (47). C9H10Br2 (278.0):
calcd. C 38.89, H 3.63, Br 57.49; found C 38.79, H 3.67, Br 57.47.
4,4-Dimethylcyclohexa-2,5-dien-1-one
(15):
Compound
13
(13.2 mL, 0.10 mol) was added to a solution of 2,3-dichloro-5,6-
dicyano-para-benzoquinone (DDQ, 45.4 g, 0.20 mol) in anhydrous
toluene (350 mL), and the thoroughly stirred reaction mixture was
heated under reflux for 24 h. The hydroquinone thus formed was
removed by filtration and carefully washed with diethyl ether. The
combined organic phases were washed with water and dried with
MgSO4. The solvent was removed in vacuo and the remaining oil
was purified first by distillation [b.p. 55 °C/8 Torr) and then by
silica gel chromatography with pentane/diethyl ether (2:1, v/v)], to
yield analytically pure 15 (6.1 g, 50%). Although the ketone has
been described in the literature,[20] its analytical data are incom-
plete. 1H NMR (400 MHz, CDCl3): δ ϭ 1.27 (s, 6 H, 7-H/8-H),
1,4-Bis(dibromomethylidene)cyclohexane (18): Compound 6 (5.6 g,
0.05 mmol) was added to a suspension of triphenylphosphane
(104.9 g, 0.40 mol) and tetrabromomethane (66.3 g, 0.20 mol) in
anhydrous toluene (400 mL). The reaction mixture was heated un-
der reflux for 18 h and the solid components were removed by fil-
tration. After these had been washed carefully with pentane, the
organic phases were combined and dried (MgSO4), and the solv-
ents were removed in vacuo. Column chromatography (silica gel,
pentane) provided 18 (8.5 g, 40%) as colorless crystals, m.p. 164 °C.
3
4
5
5
6.19 (3J2-H,3-H ϭ J5-H,6-H ϭ 10.1, J2-H,6-H ϭ 3.0, J2-H,5-H ϭ J3- 1H NMR (400 MHz, CDCl3): δ ϭ 2.50 (s, 2-H/3-H/5-H/6-H). 13C
3
ϭ 0.1 Hz, 2 H, 2-H/6-H), 6.85 (m, J2-H,3-H
10.1, J3-H,5-H ϭ 1.9, J2-H,5-H
ϭ
3J5-H,6-H
ϭ
NMR (100 MHz, CDCl3): δ ϭ 32.2 (C-2/C-3/C-5/C-6), 84.3 (C-7/
H,6-H
ϭ
5J3-H,6-H ϭ 0.1 Hz, 2 H, 3-H/5-
C-8), 141.6 (C-1/C-4). IR (KBr): ν˜ ϭ 2985 cmϪ1 (w), 2906 (m),
4
5
H). 13C NMR (100 MHz, CDCl3): δ ϭ 26.5 (C-7/C-8), 37.8 (C-4), 2840 (w), 1436 (m), 1425 (m), 1253 (s), 1197 (m), 968 (s), 838 (m),
127.1 (C-2/C-6), 156.7 (C-3/C-5), 185.7(C-1). IR (film): ν˜ ϭ 3039 782 (s). UV/Vis (n-C5H12): λmax (lg ε) ϭ 208 nm (4.39), 216 (4.36).
cmϪ1 (w), 2969 (m), 2931 (w), 2910 (w), 1689 (m), 1666 (s), 1633 GC/MS (EI): m/z (%) ϭ 428 (1) [Mϩ], 426 (5) [Mϩ], 424 (10) [Mϩ],
(m), 1471 (w), 1403 (m), 1255 (w), 1105 (w) 861 (m). UV (CH3OH): 422 (6) [Mϩ], 420 (2) [Mϩ], 347 (2), 345 (7), 343 (7), 341 (2), 266
λmax (lg ε) ϭ 234 nm (4.12). GC/MS (EI): m/z (%) ϭ 122 (22) [Mϩ],
107 (12), 94 (53), 93 (11), 91 (12), 79 (100), 78 (13), 77 (66), 67 (6), (16), 77 (20). C8H8Br4 (423.8): calcd. C 22.87, H 1.92, Br 75.21;
(47), 264 (100), 262 (53), 184 (13), 182 (13), 104 (32), 103 (33), 91
65 (6), 53 (18), 51 (17), 41 (11).
found C 22.73, H 1.77, Br 75.24.
1-(Dibromomethylidene)-4,4-dimethylcyclohexane (16): Compound
14 (3.2 g, 25 mmol) was added to a suspension of triphenylphos-
phane (26.2 g, 0.1 mol) and tetrabromomethane (16.6 g, 0.05 mol)
in anhydrous toluene (125 mL).[21] The reaction mixture was heated
under reflux for 18 h and the solid components were removed by
filtration. After these had been washed carefully with pentane, the
organic phases were combined and dried (MgSO4), and the solv-
3-(Dibromomethylidene)-6,6-dimethylcyclohex-1-ene (19): Com-
pound 19 (4.5 g, 65%) was prepared from 13 (3.3 mL, 25 mmol) as
described for 16, as a yellow oil that was stable for months in dilute
1
pentane solution. H NMR (400 MHz, CDCl3): δ ϭ 1.03 (s, 6 H,
3
8-H/9-H), 1.53 (ps-t, J4-H,5-H ϭ 6.5 Hz, 2 H, 5-H), 2.49 (ps-t,
3
3J4-H,5-H ϭ 6.5 Hz, 2 H, 4-H), 5.76 (d, J1-H,2-H ϭ 10.1 Hz, 1 H, 1-
3
H), 6.35 (d, J1-H,2-H ϭ 10.1 Hz, 1 H, 2-H). 13C NMR (100 MHz,
ents were removed in vacuo. Column chromatography (silica gel, CDCl3): δ ϭ 28.2 (C-8/C-9), 28.3 (C-4), 32.1 (C-6), 36.0 (C-5), 87.7
pentane) provided 16 (5.6 g, 80%) as a yellow, low-melting solid
(C-7), 123.4 (C-2), 138.3 (C-3), 143.8 (C-1). IR (film): ν˜ ϭ 3023
(m.p. 45Ϫ46 °C), which could be stored only for a limited time. 1H
cmϪ1 (w), 2958 (s), 2935 (m), 2925 (s), 2866 (m), 1551 (w), 1469
NMR (400 MHz, CDCl3): δ ϭ 0.96 (s, 6 H, 8-H/9-H), 1.36 (t, (m), 1376 (w), 1249 (m), 827 (m), 809 (s), 775 (s). UV/Vis (n-
3
3
3J2-H,3-H ϭ J5-H,6-H ϭ 6.5 Hz, 4 H, 3-H/5-H), 2.41 (t, J2-H,3-H
ϭ
C5H12): λmax (lg ε) ϭ 250 nm (4.12). GC/MS (EI): m/z (%) ϭ 282
3J5-H,6-H ϭ 6.5 Hz, 4 H, 2-H/6-H). 13C NMR (100 MHz, CDCl3): (23) [Mϩ], 280 (48) [Mϩ], 278 (25) [Mϩ], 267 (26), 265 (53), 263
δ ϭ 27.7 (C-8/C-9), 29.8 (C-4), 30.6 (C-2/C-6), 39.0 (C-3/C-5), 81.6 (28), 251 (9), 237 (10), 201 (46), 199 (49), 186 (34), 184 (36), 171
(C-7), 114.7 (C-1). IR (KBr): ν˜ ϭ 2961 cmϪ1 (s), 2920 (s), 2872
(10), 120 (58), 119 (44), 107 (34), 105 (100), 91 (52), 77 (58).
(m), 2844 (m), 1467 (m), 1452 (m), 1386 (w), 1367 (m), 1241 (m), C9H12Br2 (280.0): calcd. C 38.61, H 4.32, Br 57.07; found C 38.62,
1224 (m), 1168 (m), 1017 (w), 966 (m), 886 (w), 792 (s), 772 (m). H 4.38, Br 57.02.
UV/Vis (n-C5H12): λmax (lg ε) ϭ 208 nm (4.15), 216 (sh, 4.03). GC/
1-(Dichloromethylidene)-4,4-dimethylcyclohexane (20): Tetrachloro-
MS (EI): m/z (%) ϭ 284 (12) [Mϩ], 282 (24) [Mϩ], 280 (13) [Mϩ],
methane (0.48 mL, 5.0 mmol), triphenylphosphane (2.62 g,
161 (11), 159 (13), 121 (50), 109 (58), 96 (100), 81 (61), 69 (57), 65
10.0 mmol), and zinc powder (0.65 g, 10.0 mol) were added to a
solution of 14 (0.32 g, 2.5 mmol) in anhydrous dichloromethane
(30 mL). The reaction mixture was heated under reflux for 18 h,
(38), 55 (44), 43 (22). C9H14Br2 (282.0): calcd. C 38.33, H 5.00, Br
56.67; found C 38.22, H 5.01, Br 56.45.
3-(Dibromomethylidene)-6,6-dimethylcyclohexa-1,4-diene
Compound 15 (3.0 g, 25 mmol) was added to a suspension of tri-
(17):
and the solid residue was removed by filtration and carefully
washed with pentane. The solvents were removed in vacuo, and the
1714
Eur. J. Org. Chem. 2002, 1708Ϫ1721

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
FULL PAPER
remaining oil was purified by silica gel chromatography with pent-
(C-1). IR (KBr): ν˜ ϭ 3057 cmϪ1 (w), 2952 (s), 2912 (s), 2863 (m),
1
ane to yield 20 (0.19 g, 40%) as a yellow oil. H NMR (400 MHz, 2846 (m), 1590 (m), 1490 (s), 1443 (m), 1385 (m), 756 (s), 691 (s).
3
CDCl3): δ ϭ 0.95 (s, 6 H, 8-H/9-H), 1.36 (t, J2-H,3-H ϭ 3J5-H,6-H ϭ
UV/Vis (n-C5H12): λmax (lg ε) ϭ 194 nm (4.75), 224 (4.35), 268 (sh,
3
6.5 Hz, 4 H, 3-H/5-H), 2.39 (t, J2-H,3-H ϭ 3J5-H,6-H ϭ 6.5 Hz, 4 H, 4.48), 276 (4.58), 302 (sh, 4.42). GC/MS (EI): m/z (%) ϭ 324 (100)
2-H/6-H). 13C NMR (100 MHz, CDCl3): δ ϭ 27.6 (C-2/C-6), 27.7 [Mϩ], 309 (11), 267 (30), 252 (33), 239 (15), 228 (41), 215 (20), 115
(C-8/C-9), 29.8 (C-4), 38.9 (C-3/C-5), 110.9 (C-7), 137.6 (C-1). IR (14). C25H24 (324.5): calcd. C 92.54, H 7.46; found C 92.49, H 7.63.
(film): ν˜ ϭ 2955 cmϪ1 (s), 2922 (s), 2868 (m), 2850 (m), 1619 (w),
3-(1,5-Diphenylpenta-1,4-diyn-3-ylidene)-6,6-dimethylcyclohex-1-ene
1460 (m), 1444 (m), 966 (w), 905 (s), 865 (s). UV/Vis (n-C5H12):
(24): Compound 24 (0.48 g, 30%) was prepared from 19 (1.40 g,
λmax (lg ε) ϭ 206 nm (4.08), 210 (sh, 4.03). GC/MS (EI): m/z (%) ϭ
5.0 mmol) as described above for 23, as a yellow oil. 1H NMR
194 (31) [Mϩ], 192 (48) [Mϩ], 179 (8), 177 (13), 141 (17), 121 (24),
(400 MHz, CDCl3): δ ϭ 1.07 (s, 6 H, 2 ϫ CH3), 1.61 (ps-t,
109 (100), 96 (86), 91 (21), 81 (82), 77 (28), 69 (87). C9H14Cl2
(193.1): calcd. C 55.98, H 7.31, Cl 36.72; found C 55.98, H 7.33,
Cl 36.67.
3
3J4-H,5-H ϭ 6.5 Hz, 2 H, 5-H,), 2.80 (ps-t, J4-H,5-H ϭ 6.5 Hz, 2 H,
3
3
4-H), 5.87 (d, J1-H,2-H ϭ 9.9 Hz, 1 H, 1-H), 6.80 (d, J1-H,2-H
ϭ
9.9 Hz, 1 H, 2-H), 7.29Ϫ7.34 (m, 6 H, arom. H), 7.48Ϫ7.51 (m, 4
3-(Dichloromethylidene)-6,6-dimethylcyclohex-1-ene (21): Com-
H, arom. H). 13C NMR (100 MHz, CDCl3): δ ϭ 25.6 (C-4), 28.4
pound 21 (0.29 g, 60%) was prepared from 13 (0.33 mL, 2.5 mmol) (2 ϫ CH3), 32.6 (C-6), 36.1 (C-5), 85.9 and 86.7 (acetylenic C),
1
as described for 20, as a yellow oil. H NMR (400 MHz, CDCl3):
93.0 and 94.5 (acetylenic C), 99.2 (C-7), 123.4 (arom. C), 124.3 (C-
2), 128.1 and 128.2 (arom. C), 128.3 (arom. C), 131.5 (arom. C),
3
δ ϭ 1.03 (s, 6 H, 8-H/9-H), 1.53 (ps-t, 5-H, J4-H,5-H ϭ 6.6 Hz, 2
H, 5-H), 2.51 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2 H, 4-H), 5.74 (d, 145.5 (C-1), 151.0 (C-3). IR (film): ν˜ ϭ 3020 cmϪ1 (w), 2957 (s),
3
3J1-H,2-H ϭ 10.1 Hz, 1 H, 1-H), 6.31 (d, J1-H,2-H ϭ 10.1 Hz, 1 H, 2924 (m), 2864 (m), 2208 (w), 1596 (m), 1490 (s), 1469 (m), 1361
3
2-H). 13C NMR (100 MHz, CDCl3): δ ϭ 25.4 (C-4), 28.3 (C-8/C- (m), 1070 (w), 784 (m), 754 (s), 690 (s). UV/Vis (n-C5H12): λmax (lg
9), 31.9 (C-6), 35.7 (C-5), 115.2 (C-7), 121.2(C-2), 132.1 (C-3),
ε) ϭ 196 nm (4.74), 230 (4.29), 276 (sh, 4.39), 280 (4.40), 292 (4.56),
143.1 (C-1). IR (film): ν˜ ϭ 3026 cmϪ1 (w), 2959 (s), 2926 (s), 2867
332 (4.51). MS (EI): m/z (%) ϭ 322 (100) [Mϩ], 308 (10), 307 (40),
(m), 1572 (m), 1470 (m), 917 (s), 886 (s), 850 (m), 776 (s). UV/Vis 291 (12), 279 (9), 229 (10), 215 (17). HRMS (C25H22): calcd.
(n-C5H12): λmax (lg ε) ϭ 246 nm (sh, 4.32), 252 (4.36), 258 (sh,
4.23). GC/MS (EI): m/z (%) ϭ 192 (33) [Mϩ], 190 (52) [Mϩ], 177
(64), 175(100), 161 (17), 157 (25), 155 (78), 147 (17), 139 (38), 125
(14), 119 (21), 107 (23), 103 (34), 91 (30), 77 (43), 63 (17), 51 (19),
41 (29). C9H12Cl2 (191.1): calcd. C 56.57, H 6.33, Cl 37.10; found
C 56.71, H 6.48, Cl 36.95.
322.172; found 322.172 Ϯ 2 ppm.
3-(1,5-Diphenylpenta-1,4-diyn-3-ylidene)-6,6-dimethylcyclohexa-1,4-
diene (25): Compound 25 (0.48 g, 30%) was prepared from 17
(1.39 g, 5.0 mmol) as described above for 23, as a yellow needles
1
(pentane), m.p. 99 °C. H NMR (400 MHz, CDCl3): δ ϭ 1.17 (s,
6 H, 2 ϫ CH3), 6.03 (ps-d, 3J1-H,2-H ϭ 3J4-H,5-H ϭ 10.1 Hz, 2 H, 1-
3-(Dichloromethylidene)-6,6-dimethylcyclohexa-1,4-diene
Compound 22 (0.28 g, 60%) of was prepared from 15 (0.31 mL,
2.5 mmol) as described for 20, as a yellow oil. 1H NMR (400 MHz, NMR (100 MHz, CDCl3): δ ϭ 28.7 (2 ϫ CH3), 37.7 (C-6), 86.7
(22): H/5-H), 6.93 (ps-d, J1-H,2-H ϭ 3J4-H,5-H ϭ 10.1 Hz, 2 H, 32-H/4-H),
7.31Ϫ7.35 (m, 6 H, arom. H), 7.51Ϫ7.53 (m, 4 H, arom. H). 13C
3
3
CDCl3): δ ϭ (s, 6 H, 8-H/9-H), 5.86 (ps-d, J1-H,2-H ϭ J4-H,5-H
ϭ
(acetylenic C), 94.7 (acetylenic C), 97.8 (C-7), 122.4 (C-2/C-4),
123.3 (arom. C), 128.2 (arom. C), 128.3 (arom. C), 131.5 (arom.
10.1 Hz, 2 H, 1-H/ 5-H), 6.47 (ps-d, 3J1-H,2-H ϭ 3J4-H,5-H ϭ 10.1 Hz,
2 H, 2-H/4-H). 13C NMR (100 MHz, CDCl3): δ ϭ 28.9 (C-8/C-9), C), 143.1 (C-3), 143.3 (C-1/C-5). IR (KBr): ν˜ ϭ 3061 cmϪ1 (w),
36.4 (C-6), 117.0 (C-7), 119.6 (C-2/C-4), 128.3 (C-3), 140.9 (C-1/C-
1646 (m), 1488 (m), 923 (m), 813 (m), 752 (s), 688 (m). UV/Vis (n-
5). IR (film): ν˜ ϭ 3045 cmϪ1 (w), 2964 (m), 1555 (m), 1468 (m), C5H12): λmax (lg ε) ϭ 196 nm (4.80), 232 (4.32), 282 (4.40), 300
925 (s), 894 (s), 857 (s), 795 (s), 662 (m). UV/Vis (n-C5H12): λmax (4.58), 356 (4.58), 368 (sh, 4.55). GC/MS (EI): m/z (%) ϭ 320 (15)
(lg ε) ϭ 268 nm (4.45), 276 (sh, 4.39). GC/MS (EI): m/z (%) ϭ 190
(13) [Mϩ], 188 (20) [Mϩ], 177 (10), 175 (64), 173 (100), 153 (20),
138 (17), 103 (14), 102 (16), 77 (11), 51 (10). C9H10Cl2 (189.1):
calcd. C 57.17, H 5.33, Cl 37.50; found C 57.31, H 5.49, Cl 37.41.
[Mϩ], 306 (25), 305 (100), 302 (10), 289 (9), 214 (24). C25H20
(320.5): calcd. C 93.71, H 6.29; found C 93.67, H 6.38.
(E)-3-(1-Bromo-3-phenylpropyn-1-ylidene)-6,6-dimethylcyclohex-1-
ene (26): Dichloro-bis(triphenylphosphane)palladium(II) (0.035 g,
0.05 mmol) and copper(I) iodide (0.005 g, 0.03 mmol) were added
to a solution of 19 (0.70 g, 2.5 mmol) and phenylacetylene
1-(1,5-Diphenylpenta-1,4-diyn-3-ylidene)-4,4-dimethylcyclohexane
(23): Dichloro-bis(triphenylphosphane)palladium(II) (0.140 g,
0.20 mmol) and copper(I) iodide (19 mg, 0.10 mmol) were added to (0.33 mL, 3.0 mmol) in anhydrous triethylamine (30 mL). The mix-
a mixture of 16 (1.41 g, 5.0 mmol) and phenylacetylene (1.32 mL,
12.0 mmol) in anhydrous triethylamine (60 mL). After the mixture
ture was stirred for several days at room temp. and when the coup-
ling process was complete (TLC monitoring), the solid precipitates
had been stirred for several days at room temp., the reaction was were removed by filtration and washed carefully with pentane. The
complete (TLC monitoring), and the solid precipitate was removed
by filtration and washed thoroughly with pentane. The solvents
were removed in vacuo and the remaining crude coupling products
were purified by column chromatography on silica gel with pent-
ane; besides small amounts of 1,4-diphenylbuta-1,3-diyne and 1-
(1-bromo-3-phenylpropynylidene)-4,4-dimethylcyclohexane (27, see
below), compound 23 (0.41 g, 25%) was obtained as a yellow solid,
m.p. 81 °C. 1H NMR (400 MHz, CDCl3): δ ϭ 1.00 (s, 6 H, 2 ϫ
organic layers were combined, the solvent was removed in vacuo,
and the remaining oily crude product was purified by thick layer
chromatography (silica gel, pentane) to yield 26 (0.38 g, 50%) as a
yellow oil. 1H NMR (400 MHz, CDCl3): δ ϭ 1.03 (s, 6 H, 2 ϫ
3
CH3), 1.55 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2 H, 5-H), 2.56 (ps-t,
3
3J4-H,5-H ϭ 6.6 Hz, 2 H, 4-H), 5.79 (d, J1-H,2-H ϭ 10.0 Hz, 1 H, 1-
3
H), 6.58 (d, J1-H,2-H ϭ 10.0 Hz, 1 H, 2-H), 7.27Ϫ7.31 (m, 3 H,
arom. H), 7.42Ϫ7.47 (m, 2 H, arom. H). 13C NMR (100 MHz,
3
3
CH3), 1.46 (t, J2-H,3-H ϭ J5-H,6-H ϭ 6.5 Hz, 4 H, 3-H, 5-H), 2.66 CDCl3): δ ϭ 27.5 (C-4), 28.3 (2 ϫ CH3), 32.4 (C-6), 36.0 (C-5),
3
3
(t, J2-H,3-H ϭ J5-H,6-H ϭ 6.5 Hz, 4 H, 2-H/6-H), 7.29Ϫ7.34 (m, 6 86.7 (acetylenic C), 95.4 (acetylenic C), 98.6 (C-7), 122.5 (arom.
H, arom. H), 7.51Ϫ7.53 (m, 4 H, arom. H). 13C NMR (100 MHz,
C), 123.6 (C-2), 128.4 (arom. C), 128.7 (arom. C), 131.5 (arom. C),
CDCl3): δ ϭ 27.8 (2 ϫ CH3), 28.9 (C-2/C-6), 30.2 (C-4), 39.9 (C- 143.6 (C-1), 143.8 (C-3). IR (film): ν˜ ϭ 3022 cmϪ1 (w), 2957 (s),
3/C-5), 86.1 (acetylenic C), 90.9 (acetylenic C), 98.0 (C-7), 123.4 2924 (m), 2865 (m), 2195 (w), 1598 (w), 1489 (m), 1443 (m), 1296
(arom. C), 128.0 (arom. C), 128.2 (arom. C), 131.5 (arom. C) 161.1
(m), 835 (m), 781 (m), 755 (s), 732 (s), 689 (m). UV/Vis (n-C5H12):
Eur. J. Org. Chem. 2002, 1708Ϫ1721
1715

H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
λmax (lg ε) ϭ 194 nm (4.51), 230 (sh, 4.17), 240 (4.20), 298 (4.29), 27.8 (2 ϫ CH3), 28.7 (C-2/C-6), 30.1 (C-4), 39.7 (C-3/C-5), 96.1
310 (4.30), 330 (4.17). GC/MS (EI): m/z (%) ϭ 302 (96) [Mϩ], 300 (acetylenic C), 98.4 (C-7), 101.2 (acetylenic C), 163.5 (C-1). IR
(100) [Mϩ], 287 (27), 285 (28), 221 (69), 206 (35), 205 (40), 191 (KBr): ν˜ ϭ 2957 cmϪ1 (m), 2920 (m), 2850 (m), 2150 (m), 1249
(77), 189 (56), 178 (74), 165 (51), 152 (22), 139 (26), 128 (27), 115
(m), 844 (s), 761 (m). UV/Vis (n-C5H12): λmax (lg ε) ϭ 210 nm
(56), 95 (23), 91 (43), 89 (45). C17H17Br (301.2): calcd. C 67.79, H (3.88), 218 (3.94), 266 (4.28). GC/MS (EI): m/z (%) ϭ 318 (2) [Mϩ],
5.69, Br 26.53; found C 67.83, H 5.59, Br 26.61.
317 (3) [Mϩ], 316 (18) [Mϩ], 301 (12), 172 (10), 109 (17), 95 (10),
73 (100). C19H32Si2 (316.7): calcd. C 72.07, H 10.19, Si 17.74; found
C 72.14, H 10.12, Si 17.79.
1-(1-Bromo-3-phenylpropyn-1-ylidene)-4,4-dimethylcyclohexane
(27): Compound 27 (0.38 g, 50%) was prepared from 16 (0.71 g,
2.5 mmol) as described for 26, as a yellow oil. 1H NMR (400 MHz, 4,4-Dimethyl-1-(penta-1,4-diyn-3-ylidene)cyclohexane (8b): Com-
3
CDCl3): δ ϭ 0.97 (s, 6 H, 2 ϫ CH3), 1.40 (t, J5-H,6-H ϭ 6.5 Hz, 2 pound 29 (0.32 g, 1.0 mmol) was added to methanolic potassium
3
3
H, 5-H*), 1.42 (t, J2-H,3 ϭ 6.5 Hz, 2 H, 3-H*), 2.49 (t, J5-H,6-H
ϭ
hydroxide solution (1 , 4 mL), and the mixture was stirred for 1 h
3
6.5 Hz, 2 H, H-6*), 2.58 (t, J2-H,3-H ϭ 6.5 Hz, 2 H, 2-H*), at room temp. A few mL of pentane were added, the organic phase
7.30Ϫ7.35 (m, 3 H, arom. H), 7.43Ϫ7.46 (m, 2 H, arom. H). 13C
NMR (100 MHz, CDCl3): δ ϭ 27.7 (2 ϫ CH3), 29.9 (C-2*), 30.04
was separated, and the product mixture was purified by column
chromatography on silica gel with pentane to yield 8b (0.16 g, 90%);
1
(C-6*), 30.05 (C-4), 39.3 (C-5*), 39.6 (C-3*), 86.6 (acetylenic C), the solid (m.p. ca. 54 °C) quickly turned red and polymerized. H
92.8 (acetylenic C), 93.5 (C-7), 122.6 (arom. C), 128.3 (arom. C), NMR (400 MHz, CDCl3): δ ϭ 0.97 (s, 6 H, 2 ϫ CH3), 1.41 (t, J1-
3
3
128.5 (arom. C), 131.5 (arom. C), 150.7 (C-1). IR (Film): ν˜ ϭ 3081
ϭ 6.5 Hz, 4 H, 3-H/5-H), 2.55 (t, J1-H,2-H ϭ 6.5 Hz, 4 H, 2-
H,2-H
cmϪ1 (w), 3060 (w), 2953 (s), 2919 (s), 2848 (w), 2200 (w), 1490 H/6-H), 3.08 (s, 2 H, acetylenic H). 13C NMR (100 MHz, CDCl3):
(m), 1442 (m), 1386 (m), 1232 (m), 1169 (w), 755 (s), 689 (s). UV/ δ ϭ 27.7 (2 ϫ CH3), 28.7 (C-2/C-6), 30.1 (C-4), 39.6 (C-3/C-5),
Vis (n-C5H12): λmax (lg ε) ϭ 192 nm (4.47), 224 (4.20), 260 (4.16), 79.2 (terminal acetylenic C), 79.9 (acetylenic C), 95.9 (C-7), 164.4
272 (4.21), 282 (4.24), 300 (4.17). GC/MS (EI): m/z (%) ϭ 304 (54)
(C-1). GC/IR: ν˜ ϭ 3303 cmϪ1 (s), 2955 (s), 2921 (s), 2865 (m), 2849
[Mϩ], 302 (56) [Mϩ], 289 (2), 287 (2), 233 (44), 208 (46), 206 (40), (m), 2101 (w), 1592 (m), 1462 (m), 1441 (m), 1388 (m), 1170 (m),
193 (18), 181 (54), 167 (96), 165 (100), 152 (65), 139 (55), 127 (76), 977 (w). UV/Vis (n-C5H12): λmax (lg ε) ϭ 198 nm (3.72), 252 (4.18).
115 (56), 105 (20), 91 (53), 81 (30). C17H19Br (303.3): calcd. C
67.33, H 6.32, Br 26.35; found C 67.38, H 6.32, Br 26.37.
GC/MS (EI): m/z (%) ϭ 172 (82) [Mϩ], 157 (55), 143 (19), 142 (39),
129 (65), 128 (42), 116 (31), 115 (100), 102 (36), 96 (37), 91 (15),
81 (39), 77 (18). HRMS (C13H16): calcd. 172.125; found 172.125
Ϯ 2 ppm.
3-(1-Bromo-3-phenylpropyn-1-ylidene)-6,6-dimethylcyclohexa-1,4-
diene (28): Compound 28 (0.26 g, 35%) was prepared from 17
(0.69 g, 2.5 mmol) as described for 26, as a yellow oil. 1H NMR
3-[1,5-Bis(trimethylsilyl)penta-1,4-diyn-3-ylidene]-6,6-dimeth-
(400 MHz, CDCl3): δ ϭ 1.14 (s, 6 H, 2 ϫ CH3), 5.91 (dd, cyclohex-1-ene (30): Compound 30 (1.73 g, 55%) was prepared from
4
3J1-H,2-H ϭ 10.0, J1-H,5-H ϭ 2.1 Hz, 1 H, 1-H), 5.99 (dd, 19 (2.80 g, 10.0 mmol) as described for 29, as a yellow oil. 1H NMR
4
3J4-H,5-H ϭ 10.0, J1-H,5-H ϭ 2.1 Hz, 1 H, 5-H), 6.67 (dd, (400 MHz, CDCl3): δ ϭ 0.208 and 0.214 [2 ϫ s, 18 H, 2 ϫ
4
3
3J4-H,5-H ϭ 10.0, J2-H,4-H ϭ 2.1 Hz, 1 H, 4-H), 6.74 (dd, (CH3)3Si], 1.03 (s, 6 H, 2 ϫ CH3), 1.54 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2
3J1-H,2-H ϭ 10.0, 4J1-H,5-H ϭ 2.1 Hz, 1 H, 2-H), 7.32Ϫ7.35 (m, 3 H,
H, 5-H), 2.63 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2 H, 4-H), 5.83 (d,
3
arom. H), 7.46Ϫ7.49 (m, 2 H, arom. H). 13C NMR (100 MHz, 3J1-H,2-H ϭ 9.9 Hz, 1 H, 1-H), 6.63 (d, J1-H,2-H ϭ 9.9 Hz, 1 H, 2-
3
CDCl3): δ ϭ 28.5 (2 ϫ CH3), 37.4 (C-6), 87.5 (acetylenic C), 97.6
(acetylenic C), 97.7 (C-7), 121.9 (C-2), 122.5 (arom. C), 122.6 (C-
4), 128.3 (arom. C), 128.7 (arom. C), 131.4 arom C), 136.8 (C-3),
H). 13C NMR (100 MHz, CDCl3): δ ϭ 0.0 and 0.1 [2 ϫ (CH3)3Si],
25.5 (C-4), 28.4 (2 ϫ CH3), 32.6 (C-6), 36.0 (C-5), 98.2 and 99.9
(acetylenic C), 99.3 (C-7), 100.8 and 102.0 (acetylenic C), 124.2 (C-
141.3 (C-1), 143.8 (C-5). IR (film): ν˜ ϭ 3036 cmϪ1 (w), 2963 (m), 2), 146.0 (C-1), 153.2 (C-3). IR (film): ν˜ ϭ 2959 cmϪ1 (m), 2925
1650 (m), 1486 (m), 1468 (m), 1442 (m), 925 (m), 845 (s), 803 (s), (m), 2148 (m), 2132 (w), 1250 (s), 1205 (w), 843 (s), 759 (m), 668
754 (s), 688 (s), 669 (m). UV/Vis (n-C5H12): λmax (lg ε) ϭ 194 nm
(4.50), 232 (4.11), 240 (4.11), 318 (4.14), 330 (4.17), 356 (4.13). GC/ (4.39). GC/MS (EI): m/z (%) ϭ 316 (16) [Mϩ], 315 (17) [Mϩ], 314
MS (EI): m/z (%) ϭ 300 (24) [Mϩ], 298 (24) [Mϩ], 285 (27), 283 (63) [Mϩ], 302 (7), 301 (3), 299 (27), 211 (8), 142 (31), 107 (17), 97
(m). UV/Vis (n-C5H12): λmax (lg ε) ϭ 216 nm (3.99), 224 (4.05), 308
(100), 219 (65), 204 (77), 203 (44), 202 (84), 189 (54), 176 (9), 150 (12), 83 (9), 73 (100), 59 (18). C19H30Si2 (314.7): calcd. C 72.54, H
(7), 101 (16). C17H15Br (299.2): calcd. C 68.24, H 5.05, Br 26.70; 9.61, Si 17.85; found C 72.64, H 9.59, Si 17.71.
found C 68.25, H 5.15, Br 26.68.
6,6-Dimethyl-3-(penta-1,4-diyn-3-ylidene)cyclohex-1-ene (9b): Com-
1-[1,5-Bis(trimethylsilyl)penta-1,4-diyn-3-ylidene]-4,4-dimethyl- pound 30 (0.31 g, 1.0 mmol) was hydrolyzed with methanolic pot-
cyclohexane (29): Dichlorobis(triphenylphosphane)palladium(II)
(0.280 g, 0.40 mmol) and copper(I) iodide (0.038 g, 0.20 mmol)
were added to a solution of 16 (2.82 g, 10.0 mmol) and trimethylsi-
assium hydroxide as described for 8b to yield 9b (0.15 g, 90%),
which quickly turned red and polymerized (even in solution). 1H
NMR (400 MHz, CDCl3): δ ϭ 1.04 (s, 6 H, 2 ϫ CH3), 1.56 (ps-t,
3
lylacetylene (3.32 mL, 24.0 mmol) in anhydrous triethylamine 3J4-H,5-H ϭ 6.6 Hz, 2 H, 5-H), 2.67 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2 H,
3
(120 mL). After the mixture had been stirred for several days at
4-H), 3.20 (s, 1 H, 9-H), 3.27 (s, 1 H, 11-H), 5.87 (d, J1-H,2-H
ϭ
room temp., with the progress of the reaction monitored by TLC, 9.9 Hz, 1 H, 1-H), 6.64 (d, 3J1-H,2-H ϭ 9.9 Hz, 1 H, 2-H). 13C NMR
the precipitates were removed by filtration and washed thoroughly
with pentane. The solvents were removed in vacuo and the product
mixture was purified by column chromatography on silica gel with
pentane. Besides traces of 1,4-bis(trimethylsilyl)buta-1,3-diyne and
1-[1-bromo-3-(trimethylsilyl)propyn-1-ylidene]-4,4-dimethylcyclo-
hexane, compound 29 (1.58 g, 50%) was obtained as a yellow solid,
(100 MHz, CDCl3): δ ϭ 25.4 (C-4), 28.3 (C-12/C-13), 32.5 (C-6),
35.8 (C-5), 79.7 (C-8), 80.7 (C-10), 81.1 (C-9), 82.5 (C-11), 96.9 (C-
7), 123.7 (C-2), 146.6 (C-1), 154.0 (C-3). IR (film): ν˜ ϭ 3307 cmϪ1
(s), 3298 (s), 2958 (s), 2926 (s), 2866 (m), 2098 (w), 1604 (w), 1470
(m), 1460 (w), 1361 (w), 914 (w), 790 (m), 653 (s). UV/Vis (n-
C5H12): λmax (lg ε) ϭ 200 nm (3.80), 292 (4.24). GC/MS (EI): m/z
(%) ϭ 170 (100) [Mϩ], 155 (72), 154 (17), 153 (40), 152 (26), 141
(26), 139 (28), 129 (18), 128 (56), 127 (55), 115 (39), 107 (19), 91
(18), 77 (21). HRMS (C13H14): calcd. 170.110; found 170.110 Ϯ
1
m.p. 73 °C. H NMR (400 MHz, CDCl3): δ ϭ 0.19 [s, 18 H, 2 ϫ
3
3
(CH3)3Si], 0.96 (s, 6 H, 2 ϫ CH3), 1.40 (t, J2-H,3-H ϭ J5-H,6-H
ϭ
6.5 Hz, 4 H, 3-H/5-H), 2.52 (t, J2-H,3-H ϭ 3J5-H,6-H ϭ 6.5 Hz, 4 H,
3
2-H/6-H). 13C NMR (100 MHz, CDCl3): δ ϭ 0.0 [2 ϫ (CH3)3Si], 2 ppm.
1716
Eur. J. Org. Chem. 2002, 1708Ϫ1721

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
3-[1,5-Bis(trimethylsilyl)penta-1,4-diyn-3-ylidene]-6,6-dimethyl- 1,4-Bis(penta-1,4-diyn-3-ylidene)cyclohexane (33): A solution of
FULL PAPER
cyclohexa-1,4-diene (31): Compound 31 (2.03 g, 65%) was prepared
tetra-n-butylammonium fluoride in water (1 , 1 mL) was added
to a solution of 32 (0.10 g, 0.20 mmol) in pentane (6 mL). The two-
from 17 (2.78 g, 10.0 mmol) as described for 29, as a yellow solid,
1
m.p. 77 °C. H NMR (400 MHz, CDCl3): δ ϭ 0.22 [s, 18 H, 2 ϫ phase reaction mixture was vigorously stirred for 18 h, and after
(CH3)3Si], 1.12 (s, 6 H, 2 ϫ CH3), 5.99 (ps-d, J1-H,2-H
ϭ
the organic layer had been separated the solvent was removed in
vacuo. The remainder was taken up in dichloromethane and chro-
3
3J4-H,5-H ϭ 10.1 Hz, 2 H, 31-H, 5-H), 6.77 (ps-d, J1-H,2-H
ϭ
3J4-H,5-H ϭ 10.1 Hz, 2 H, 2-H, 4-H). 13C NMR (100 MHz, CDCl3): matographed on silica gel to yield 33 (0.030 g, 75%) as a red solid,
δ ϭ 0.0 [2 ϫ (CH3)3Si], 28.6 (C-12/C-13), 37.7 (C-6), 97.8 (C-7), m.p. 155 °C, which (even in dilute solution) rapidly polymerized.
100.3 (acetylenic C), 101.5 (acetylenic C), 122.3 (C-2/C-4), 143.7
(C-1/C-5), 145.0 (C-3). IR (KBr): ν˜ ϭ 3037 cmϪ1 (m), 3010 (m),
2960 (s), 2933 (m), 2918 (m), 2899 (m), 2145 (s), 2135 (m), 2124
1H NMR (400 MHz, CDCl3): δ ϭ 2.68 (s, 8 H, 2-H/3-H/5-H/6-H),
3.14 (s, 4 H, acetylenic H). 13C NMR (100 MHz, CDCl3): δ ϭ 31.4
(C-2/C-3/C-5/C-6), 79.4 (acetylenic C), 80.4 (terminal acetylenic C),
(m), 1647 (m), 1324 (m), 1251 (s), 1208 (m), 1119 (m), 1008 (m), 98.2 (C-7/C-12), 160.5 (C-1/C-4). UV/Vis (acetonitrile): λmax (lg
923 (m), 854 (s), 841 (s), 813 (s), 757 (s), 700 (m), 685 (m). UV/Vis ε) ϭ 198 nm, 266. MS (EI): m/z (%) ϭ 204 (42) [Mϩ], 202 (100),
(n-C5H12): λmax (lg ε) ϭ 226 nm (4.03), 242 (3.99), 250 (3.96), 340
189 (29), 176 (22), 165 (10), 152 (9), 115 (14), 89 (8). HRMS
(4.52), 354 (sh, 4.37). GC/MS (EI): m/z (%) ϭ 314 (2) [Mϩ], 313 (C16H12): calcd. 204.094; found 204.094 Ϯ 2 ppm.
(5) [Mϩ], 312 (12) [Mϩ], 299 (4), 298 (11), 297 (24), 282 (5), 255
(9), 224 (39), 206 (13), 191, 179 (26), 173 (11), 141, 97 (17), 73
(100). C19H28Si2 (312.65): calcd. C 73.00, H 9.03, Si 17.97; found
C 73.06, H 9.17, Si 17.98.
1,4-Bis[1,5-bis(trimethylsilyl)penta-1,4-diyn-3-ylidene]cyclo-
hex-2-ene
(35):
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone
(0.090 g, 0.40 mmol) was added to a solution of 32 (0.049 g,
0.10 mmol) in anhydrous dioxane (3 mL) and the reaction mixture
was heated to reflux for 4 h. Without further workup, the product
mixture was subjected to thick-layer chromatography on silica gel
(pentane) to yield 35 (0.010 g, 20%) as an orange solid, m.p. 222
6,6-Dimethyl-3-(penta-1,4-diyn-3-ylidene)cyclohexa-1,4-diene (10b):
Compound 31 (0.31 g, 1.0 mmol) was hydrolyzed with methanolic
potassium hydroxide as described for 8b to yield 10b (0.15 g, 90%)
1
°C. H NMR (400 MHz, CDCl3): δ ϭ 0.22 and 0.23 [2 ϫ s, 2 ϫ
1
as a red oil that quickly polymerized (even in solution). H NMR
18 H, 4 ϫ (CH3)3Si], 2.71 (s, 4 H, 5-H/6-H), 6.94 (s, 2 H, 2-H/3-
H). 13C NMR (100 MHz, CDCl3): δ ϭ 0.0 [4 ϫ (CH3)3Si], 26.9 (C-
5/C-6), 100.1, 100.5, 101.9, 102.2 and 102.6 (C-7/C-12 and acetyl-
enic C), 130.5 (C-2/C-3), 151.3 (C-1/C-4). IR (KBr): ν˜ ϭ 2958 cmϪ1
(m), 2924 (m), 2854 (w), 2144 (m), 2129 (w), 1323 (w), 1247 (m),
1220 (w), 1014 (m), 853 (s), 843 (s), 757 (m). UV/Vis (n-C5H12):
λmax (lg ε) ϭ 226 nm (4.03), 242 (3.99), 250 (3.96), 340 (4.52), 354
(sh, 4.37). MS (EI): m/z (%) ϭ 494 (2) [Mϩ], 493 (9) [Mϩ], 492 (26)
[Mϩ], 491 (51) [Mϩ], 490 [Mϩ] (100), 73 (26). HRMS (C28H42Si4):
calcd. 490.236; found 490.236 Ϯ 2 ppm.
(400 MHz, CDCl3): δ ϭ 1.12 (s, 6 H, 12-H/13-H), 3.32 (s, acetylenic
H), 6.03 (ps-d, 3J1-H,2-H ϭ 3J4-H,5-H ϭ 10.1 Hz, 2 H, 1-H/5-H), 6.79
3
(ps-d, J1-H,2-H
ϭ
3J4-H,5-H ϭ 10.1 Hz, 2 H, H-2/H-4). 13C NMR
(100 MHz, CDCl3): δ ϭ 28.5 (C-12/C-13), 37.7 (C-6), 80.5 (C-8/C-
10), 82.8 (C-9/C-11), 95.4 (C-7), 122.0 (C-2/C-4), 144.4 (C-1/C-5),
145.9 (C-3). GC/IR: ν˜ ϭ 3325 cmϪ1 (s), 2973 (m), 2877 (w), 2097
(w), 1650 (w), 1195 (m), 921 (m), 810 (m). HPLC/UV (n-C5H12):
λmax ϭ 240 nm, 340. GC/MS (EI): m/z (%) ϭ 168 (26) [Mϩ], 154
(30), 153 (100), 152 (42), 151 (16), 127 (6), 77 (9). HRMS (C13H12):
calcd. 168.094; found 168.094 Ϯ 2 ppm.
1,4-Bis(1,5-diphenylpenta-1,4-diyn-3-ylidene)cyclohex-2-ene (36)
1,4-Bis[1,5-bis(trimethylsilyl)penta-1,4-diyn-3-ylidene]cyclo-
hexane (32): A solution of methylmagnesium bromide in diethyl
ether (3 , 9.50 mL, 28.5 mmol) was slowly added at Ϫ78 °C to a
solution of trimethylsilylacetylene (4.15 mL, 30.0 mmol) in anhyd-
rous THF (40 mL). The resulting suspension was allowed to warm
to room temp. and heated to reflux for 2 h. The reaction mixture
was again cooled to Ϫ78 °C, and 18 (2.12 g, 5.0 mmol) in anhyd-
rous THF (50 mL) and [1,3-bis(diphenylphosphanyl)propane]nick-
el(II) chloride (0.54 g, 1.0 mmol) were swiftly added. The reaction
mixture was again slowly allowed to warm to room temp. and
150 mL of saturated ammonium chloride solution was added for
hydrolysis. After the addition of 20 mL of diethyl ether and 20 mL
of pentane, the organic phase was separated, washed with water,
and dried with Na2SO4. The solid remaining after solvent removal
in vacuo was recrystallized from diethyl ether to yield 32 (1.23 g,
50%) as an intensely yellow solid, m.p. 236 °C. 1H NMR
(400 MHz, CDCl3): δ ϭ 0.21 [s, 36 H, 4 ϫ (CH3)3Si], 2.63 (s, 8 H,
2-H/3-H/5-H/6-H). 13C NMR (100 MHz, CDCl3): δ ϭ 0.0 [4 ϫ
(CH3)3Si], 31.3 (C-2/C-3/C-5/C-6), 97.3 (acetylenic C), 100.3 (C-7/
C-12), 100.6 (acetylenic C), 159.8 (C-1/C-4). IR (KBr): ν˜ ϭ 2962
cmϪ1 (m), 2899 (w), 2152 (m), 2125 (w), 1310 (w), 1249 (s), 1210
(w), 1005 (m), 856 (s), 841 (s), 759 (m). UV/Vis (n-C5H12): λmax (lg
ε) ϭ 208 nm (4.19), 218 (4.23), 284 (4.54), 292 (sh, 4.39). MS (EI):
m/z (%) ϭ 496 (2) [Mϩ], 495 (5) [Mϩ], 494 (14) [Mϩ], 493 (25)
[Mϩ], 492 (48) [Mϩ], 477 (13), 420 (12), 419 (17), 404 (12), 389
(21), 332 (12), 331 (26), 316 (15), 315 (16), 301 (12), 285 (12), 257
a) For the preparation of this dihydro-TEQ derivative, compound
32 (0.49 g, 1.0 mmol) in anhydrous THF (5 mL) was first treated
with a solution of tetra-n-butylammonium fluoride in THF (1 ,
5 mL, 5.0 mmol). After 5 min, the desilylated hydrocarbon 33 was
added to a suspension of phenyl iodide (0.54 mL, 4.8 mmol),
dichlorobis(triphenylphosphano)palladium(II) (0.281 g, 0.4 mmol),
and copper(I) iodide (0.038 g, 0.2 mmol) in anhydrous triethylam-
ine (15 mL). After the reaction mixture had been stirred for 3 h at
room temp., the solid residue was removed by filtration and care-
fully washed with pentane. The solvents were removed in vacuo,
and excess phenyl iodide was removed by silica gel chromatography
(pentane). Additional thick-layer chromatography (silica gel, pent-
ane/dichloromethane, 1:1, v/v) furnished orange-colored 1,4-
bis(1,5-diphenylpenta-1,4-diyn-3-ylidene)cyclohexane
(0.050 g,
10%), m.p. 270 °C. 1H NMR (400 MHz, CDCl3): δ ϭ 2.87 (s, 8 H,
2-H/3-H/5-H/6-H), 7.31Ϫ7.35 (m, 12 H, arom. H), 7.50Ϫ7.52 (m,
8 H, arom. H). 13C NMR (100 MHz, CDCl3): δ ϭ 31.9 (C-2/C-3/
C-5/C-6), 85.6 (acetylenic C), 91.9 (acetylenic C), 100.0 (C-7/C-12),
123.1 (arom. C), 128.3 (arom. C), 128.3 (arom. C), 131.5 (arom.
C), 157.5 (C-1/C-4). IR (KBr): ν˜ ϭ 3055 cmϪ1 (w), 2960 (w), 2201
(w), 1950 (w), 1490 (s), 1442 (m), 755 (s), 689 (s). UV/Vis (aceto-
nitrile): λmax (lg ε) ϭ 194 nm (5.00), 224 (4.57), 266 (4.65), 278
(4.73), 308 (4.63). MS (EI): m/z (%) ϭ 508 (100) [Mϩ], 493 (9), 431
(26), 415 (29), 353 (14), 339 (14), 252 (10), 213 (13), 115 (14).
HRMS (C40H28): calcd. 508.219; found 508.219 Ϯ 2 ppm.
(9), 155 (7), 73 (100). (C28H44Si4, 493.1): calcd. C 68.26, H 9.01, Si b) 1,4-Bis(1,5-diphenylpenta-1,4-diyn-3-ylidene)cyclohex-2-ene (36):
22.73; found C 68.11, H 8.91, Si 22.65.
2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (0.045 g, 0.20 mmol)
Eur. J. Org. Chem. 2002, 1708Ϫ1721
1717

H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
3
4
5
was added to a solution of the hydrocarbon prepared under a)
(0.025 g, 0.05 mmol) in anhydrous dioxane (2 mL), and the mixture
was heated under reflux for 4 h. Without further workup, the mix-
ture was subjected to thick-layer chromatography (silica gel, pent-
ane) to yield orange-colored 36 (0.005 g, 20%). 1H NMR
2 H, 6-H), 5.57 (ddt, J1-H,6-H ϭ 4.5, J1-H,3-H ϭ 1.5, J1-H,4-H ϭ
3
4
1.1 Hz, 1 H, 1-H), 5.61 (dd, J3-H,4-H ϭ 9.6, J1-H,3-H ϭ 1.5 Hz, 1
3
5
H, 3-H), 5.64 (dd, J3-H,4-H ϭ 9.6, J1-H,4-H ϭ 1.1 Hz, 1 H, 4-H),
16.41 (s, 1 H, OH). 13C NMR (100 MHz, CDCl3): δ ϭ 23.5 (2 ϫ
CH3), 27.7 (gem-dimethyl), 30.4 (C-5), 38.1 (C-6), 114.2 (C-7),
(400 MHz, CDCl3): δ ϭ 2.96 (s, 4 H, 5-H/6-H), 7.17 (s, 2 H, 2-H/ 125.4 (C-3), 126.9 (C-1), 130.7 (C-2), 138.9 (C-4), 190.8 (CϪO). IR
3-H), 7.34Ϫ7.37 (m, 12 H, arom. H), 7.51Ϫ7.54 (m, 8 H, arom. (film): ν˜ ϭ 3024 cmϪ1 (w), 2958 (s), 2923 (m), 2869 (m), 2809 (w),
H). 13C NMR (100 MHz, CDCl3): δ ϭ 27.2 (C-5/C-6), 85.9 and 1606 (s), 1579 (s), 1468 (m), 1420 (s), 1405 (s), 1359 (m), 1334 (m),
87.4 (acetylenic C), 94.5 and 96.4 (acetylenic C), 102.5 (C-7/C-12),
1301 (m), 990 (m), 920 (m), 763 (m), 651 (m). UV/Vis (methanol):
123.0 and 123.1 (arom. C), 128.3 and 128.4 (arom. C), 128.5 and λmax (lg ε) ϭ 204 nm (3.62), 282 (3.96). GC/MS (EI): m/z (%) ϭ
128.6 (arom. C), 130.2 (C-2/C-3), 131.6 (arom. C), 149.4 (C-1/C- 206 (21) [Mϩ], 191 (13), 163 (10), 150 (15), 131 (9), 43 (100).
4). IR (KBr): ν˜ ϭ 2953 cmϪ1 (w), 2925 (m), 2854 (w), 2188 (w),
C13H18O2 (206.3): calcd. C 75.69, H 8.80, O 15.51; found C 75.59,
1490 (m), 753 (s), 688 (s). UV/Vis (CH3CN): λmax (lg ε) ϭ 196 nm H 8.70, O 15.50.
(5.00), 238 (4.54), 292 (4.50), 308 (4.53), 434 (4.65). MS (EI): m/z
(%) ϭ 506 (100) [Mϩ], 427 (5), 352 (2), 291 (6), 253 (11). HRMS
(C40H26): calcd. 506.203; found 506.203 Ϯ 2 ppm.
b) Compound 43: 1H NMR (400 MHz, CDCl3): (E) isomer: δ ϭ
1.04 (s, 6 H, gem-dimethyl), 1.53 (ps-t, J4-H,5-H ϭ 6.6 Hz, 2 H, 5-
3
4
H), 2.21 (s, 3 H, CH3-CO), 2.97 (ps-dt, 3J4-H,5-H ϭ 6.6, J4-H,7-H
ϭ
3-(2,4-Dimethylpenta-1,4-dien-3-ylidene)-6,6-dimethylcyclohex-1-
ene (37): Water (0.22 mL) was slowly added at Ϫ23 °C, with vigor-
ous stirring, to a solution of trimethylaluminium (2  in hexane,
12 mL, 24.0 mmol) and dicyclopentadienezirconium dichloride
(0.47 g, 1.6 mmol) in anhydrous dichloromethane (30 mL). After
10 min, compound 9b (0.68 g, 4.0 mmol) in dichloromethane
(6.5 mL) was added, and the mixture was stirred for an additional
10 min at Ϫ23 °C. The reaction mixture was allowed to warm to
room temp., and satd. aqueous potassium carbonate solution
(3 mL) was added. After completion of the hydrolysis, magnesium
sulfate (5 g) was added for drying, the solid material was removed
by filtration, and the mother liquor was extracted with pentane.
The solvents were removed in vacuo, and the remaining oil was
purified by column chromatography on silica gel with pentane to
yield 37 (0.73 g, 90%) as a yellow oil. 1H NMR (400 MHz, CDCl3):
3
1.9 Hz, 2 H, 4-H), 5.92 (d, J1-H,2-H ϭ 9.8 Hz, 1 H, 1-H), 5.98 (s,
1 H, 7-H), 6.01 (d, J1-H,2-H ϭ 9.8 Hz, 1 H, 2-H); (Z) isomer: δ ϭ
3
3
1.05 (s, 6 H, gem-dimethyl), 1.62 (ps-t, J4-H,5-H ϭ 6.5 Hz, 2 H, 5-
H), 2.19 (s, 3 H, CH3-CO), 2.39 (ps-dt, J4-H,5-H ϭ 6.5, 4J4-H,7-H
ϭ
3
3
1.3 Hz, 2 H, 4-H), 5.88 (s, 1 H, 7-H), 5.97 (d, J1-H,2-H ϭ 10.2 Hz,
1 H, 1-H), 7.31 (d, J1-H,2-H ϭ10.2 Hz, 1 H, 2-H). 13C NMR
3
(100 MHz, CDCl3): (E) isomer: δ ϭ 23.8 (C-4), 28.1 (gem-di-
methyl), 28.3 (CH3-CO), 32.2 (C-6), 35.7 (C-5), 122.4 (C-7), 127.8
(C-2), 149.4 (C-1), 152.0 (C-3), 199.1 (CϭO); (Z) isomer: δ ϭ 28.1
(gem-dimethyl), 29.2 (C-4), 31.7 (CH3-CO), 32.7 (C-6), 36.5 (C-5),
120.8 (C-7), 122.7 (C-2), 149.4 (C-1), 150.4 (C-3), 198.7 (CϭO). IR
(film), mixture of isomers: ν˜ ϭ 3017 cmϪ1 (w), 2957 (s), 2937 (m),
2925 (s), 2866 (m), 1678 (s), 1610 (s), 1585 (s), 1470 (m), 1448 (m),
1355 (m), 1282 (m), 1248 (m), 1178 (s), 971 (w). UV/Vis (CH3OH),
mixture of isomers: λmax (lg ε) ϭ 204 nm (3.61), 284 (4.24). (E)
isomer: GC/MS (EI): m/z (%) ϭ 164 (60) [Mϩ], 149 (100), 131 (31),
121 (28), 116 (13), 108 (44), 105 (22), 95 (14), 93 (22), 91 (47), 79
(23), 77 (22); (Z) isomer: GC/MS (EI): m/z (%) ϭ 164(35) [Mϩ],
149 (55), 131 (15), 121 (16), 116, 108 (100), 105 (13), 95 (14), 93
(16), 91 (27), 79 (15), 77 (14). HRMS (C11H16O, mixture of iso-
mers): calcd. 164.120; found 164.120 Ϯ 3 ppm.
3
δ ϭ 1.01 (s, 6 H, gem-dimethyl), 1.49 (ps-t, J4-H,5-H ϭ 6.4 Hz, 2
H, 5-H), 1.75 (s, 3 H, CH3), 1.77 (s, 3 H, CH3), 2.38 (ps-t,
3J4-H,5-H ϭ 6.4 Hz, 2 H, 4-H), 4.75 (m, 2 H, ϭCH2), 5.05Ϫ5.07 (m,
3
2 H, ϭCH2), 5.47 (d, J1-H,2-H ϭ 10.1 Hz, 1 H, 1-H), 6.27 (d,
3J1-H,2-H ϭ 10.1 Hz, 1 H, H-2). 13C NMR (100 MHz, CDCl3): δ ϭ
22.6 (2 ϫ CH3), 24.8 (C-4), 29.1 (gem-dimethyl), 32.0 (C-6), 37.4
(C-5), 114.8 (ϭCH2), 115.8 (ϭCH2), 124.9 (C-2), 128.9 (C-3), 139.2
(C-1), 141.0 (C-7), 143.6 (Cϭ), 143.9 (Cϭ). IR (film): ν˜ ϭ 3078
cmϪ1 (m), 3020 (m), 2956 (s), 2940 (s), 2918 (s), 2865 (m), 1629
(m), 1469 (m), 1450 (m), 1370 (m), 1359 (w), 898 (s), 785 (m). UV/
Vis (n-C5H12): λmax (lg ε) ϭ 192 nm (4.11), 256 (4.15). GC/MS (EI):
m/z (%) ϭ 202 (44) [Mϩ], 187 (59), 160 (18), 159 (23), 146 (41), 145
(64), 143 (10), 132 (13), 131 (100), 129 (19), 128 (17), 119 (21), 117
(18), 115 (19), 107 (14), 105 (38), 93 (14), 91 (50), 81 (23). C15H22
(202.4): calcd. C 89.04, H 10.96; found C 89.00, H 10.98.
3,7,7-Trimethyl-2-(1-methylethenyl)tricyclo[4.3.0.01·5]non-2-ene
(42): A solution of 37 (0.81 g, 4.0 mmol) in anhydrous pentane
(200 mL) was irradiated with a low-pressure mercury lamp (λ ϭ
254 nm, 15 W) in a falling-film apparatus. The reaction progress
was monitored by GC and when the starting material had been
consumed, the solvent was removed in vacuo and the remaining oil
was purified by thick-layer chromatography on silica gel with hex-
ane to yield 42 (0.24 g, 30%) as a colorless oil. 1H NMR (400 MHz,
3
CDCl3): δ ϭ 0.56 (d, J5-H,6-H ϭ 2.7 Hz, 1 H, 6-H), 0.99 (s, 3 H, 1
5,5-Dimethyl-2-[1-(1-oxoethyl)-2-oxopropyl]cyclohexa-1,3-diene
(44): A solution of 9b (0.68 g, 4.0 mmol) in methanol (2 mL) was
added to a mixture of concd. sulfuric acid (0.6 mL), water (1.2 mL),
and mercury(II) sulfate (0.025 g). After having been heated at 60
°C for 4 h, the reaction mixture was allowed to cool to room temp.,
and diethyl ether (50 mL) was added. The mixture was washed sev-
eral times with water, the organic phase was dried, and after solvent
removal in vacuo, the remainder was purified by column chromato-
graphy followed by thick-layer chromatography on silica gel with
pentane/diethyl ether (9:1, v/v) to yield 44 (0.24 g, 35%) as a yellow
oil and 6,6-dimethyl-3-(2-oxopropylidene)cyclohex-1-ene (43,
0.070 g, 10%) as a mixture of isomers [(E): 67%, (Z): 33%; GC ana-
lysis].
ϫ Me of gem-dimethyl), 1.00 (s, 3 H, 1 ϫ Me of gem-dimethyl),
2
3
3
1.04 (ddd, J8-Ha,8-Hb ϭ 12.4, J8-Ha,9-Hb ϭ 11.8, J8-Ha,9-Ha
ϭ
2
3
7.6 Hz, 1 H, 8-Ha), 1.25 (dd, J8-Ha,8-Hb ϭ 12.4, J8-Hb,9-Hb
ϭ
3
3
8.1 Hz, 1 H, 8-Hb), 1.28 (ddd, J4-Hb,5-H ϭ 7.9, J5-H,6-H ϭ 2.7,
3J4-Ha,5-H ϭ 1.1 Hz, 1 H, 5-H), 1.58 (dd, 3 H, J4-H,b 13-H ϭ 1.4,
4
2
4J4-Ha,13-H
ϭ
1.0 Hz, 13-H), 1.65 (dd, J9-Ha,9-Hb
ϭ
12.1,
3J8-Ha,9-Ha ϭ 7.6 Hz, 1 H, 9-Ha), 1.86 (dd, J(E)-11-H,12-H ϭ 1.5,
4
4J(Z)-11-H,12-H ϭ 0.8 Hz, 3 H, 12-H), 1.98 (ddd, J9-Ha,9-Hb ϭ 12.1,
2
3J8-Ha,9-Hb ϭ 11.8, J8-Hb,9-Hb ϭ 8.1 Hz, 1 H, 9-Hb), 2.12 (dd,
3
2J4-Ha,4-Hb ϭ 17.6, J4-Ha,5-H ϭ 1.1 Hz, 1 H, 4-Ha), 2.61 (ddq,
3
2J4-Ha,4-Hb ϭ 17.6, J4-Hb,5-H ϭ 7.9, J4-Hb,13-H ϭ 1.4 Hz, 1 H, 4-
3
4
Hb), 4.69 (d, 2J(E)-11-H,(Z)-11-H ϭ 3.1, 4J(Z)-11-H,12-H ϭ 0.8 Hz, 1 H, ϭ
2
4
CH2), 4.99 (d, J(E)-11-H,(Z)-11-H ϭ 3.1, J(E)-11-H,12-H ϭ 1.5 Hz, 1
1
a) Compound 44: H NMR (400 MHz, CDCl3): δ ϭ 1.05 (s, 6 H, H, ϭCH2). 13C NMR (100 MHz, CDCl3): δ ϭ 14.6 (C-13), 21.1
3
gem-dimethyl), 2.04 (s, 6 H, 2 ϫ CH3), 2.21 (d, J1-H,6-H ϭ 4.5 Hz,
(C-5), 22.5 (C-12), 25.8 (C-9), 25.9 (gem-dimethyl), 28.8 (gem-di-
Eur. J. Org. Chem. 2002, 1708Ϫ1721
1718

En Route to 7,7,8,8-Tetraethynyl-p-quinodimethane
FULL PAPER
3
methyl), 37.4 (C-8), 39.0 (C-7), 40.2 (C-4), 45.4 (C-6), 45.5 (C-1), (Z)-H], 5.11Ϫ5.12 [m, 2 H, ϭCH2, (E)-H], 5.62 (ps-d, J1-H,2-H
ϭ
3
113.4 (ϭCH2), 130.8 (C-3), 141.0 (C-2), 151.5 (C-10). IR (film):
3J4-H,5-H ϭ 10.2 Hz, 2 H, 1-H/5-H), 6.27 (ps-d, J1-H,2-H
ϭ
ν˜ ϭ 3080 cmϪ1 (w), 3018 (m), 2954 (s), 2923 (s), 2894 (s), 2867 (s), 3J4-H,5-H ϭ 10.2 Hz, 2 H, 2-H/4-H). 13C NMR (100 MHz, CDCl3):
2832 (m), 1631 (w), 1463 (m), 1445 (m), 1376 (m), 1370 (m), 1362 δ ϭ 22.5 (CH3-Cϭ), 29.9 (gem-dimethyl), 35.6 (C-6), 115.8 (ϭ
(m), 893 (s). UV/Vis (n-C5H12): λmax (lg ε) ϭ 240 nm (3.66). MS CH2), 123.0 (C-2/C-4), 124.9 (C-3), 137.8 (C-1/C-5), 141.7 (C-7),
(EI): m/z (%) ϭ 202 (67) [Mϩ], 187 (69), 159 (16), 146 (72), 145
143.2 (Cϭ). IR (film): ν˜ ϭ 3079 cmϪ1 (m), 3038 (m), 3010 (w),
(34), 131 (100), 105 (16), 91 (16). HRMS (C15H22): calcd. 202.172; 2966 (s), 2956 (s), 2918 (m), 2865 (m), 1627 (w), 1469 (m), 1445
found 202.172 Ϯ 2 ppm.
(m), 1370 (m), 1355 (w), 1251 (w), 925 (m), 900 (s), 806 (s), 676
(m). UV/Vis (n-C5H12): λmax (lg ε) ϭ 276 nm (4.23). GC/MS (EI):
m/z (%) ϭ 200 [Mϩ], 186 (15), 185 (100), 170 (20), 157 (21), 155
(16), 143 (23), 128 (21), 115 (16), 105 (15), 91 (12), 77 (11). HRMS
(C15H20-CH3): calcd. 185.133; found 185.133 Ϯ 2 ppm.
3-(2,4-Dimethylpenta-1,4-dien-3-ylidene)-6,6-dimethylcyclohexa-1,4-
diene (45): A sample of 31 (0.63 g, 2.0 mmol) was added to potas-
sium hydroxide solution (1  in methanol, 4 mL), and the mixture
was stirred for 1 h at room temp. Pentane (25 mL) was added to
the solution, which was carefully washed with water and, after dry-
ing with sodium sulfate, was concentrated to approx. 2 mL. Separ-
3-(2,4-Dioxopent-3-ylidene)-6,6-dimethylcyclohexa-1,4-diene (46): A
sample of 31 (0.63 g, 2.0 mmol) was dissolved in potassium hydrox-
ately, a solution of trimethylaluminium (2  in hexane, 6 mL, ide solution (1  in methanol, 4 mL) and the mixture was stirred
12.0 mmol) and of dicyclopentadienezirconium dichloride (0.24 g, for 1 h at room temp. The formed 10b was taken up in pentane,
0.8 mmol) in anhydrous dichloromethane (15 mL) was cooled to and the solution was washed several times with water and dried
Ϫ23 °C, and water (0.11 mL) was added with vigorous stirring.
After 10 min, the solution of the formed 10b was added and the
mixture was stirred at Ϫ23 °C for an additional 10 min. The reac-
tion mixture was brought to room temp. and a saturated aqueous
potassium carbonate solution (1.5 mL) was added. After the hydro-
lysis had come to an end, magnesium sulfate (2.5 g) was added, the
solid materials were removed by filtration, and the crude product
with sodium sulfate. The solution was concentrated to ca. 2 mL
and added to a mixture of water (0.6 mL), concd. sulfuric acid
(0.3 mL), and mercury(II) sulfate (0.013 g). After having been
heated at 60 °C for 4 h, the reaction mixture was dissolved in di-
ethyl ether (20 mL) and the organic phase was washed thoroughly
with water. After solvent removal in vacuo, the residue was chroma-
tographed on silica gel and the main fraction was further separated
mixture was carefully extracted with pentane. The solvents were by thick-layer chromatography on silica gel with a mixture of pent-
removed in vacuo and the residue was purified by column chroma-
tography on silica gel with pentane to yield 45 (0.36 g, 90%) as a
yellow oil. 1H NMR (400 MHz, CDCl3): δ ϭ 1.09 (s, 6 H, gem-
ane and diethyl ether (9:1, v/v) in both purification steps to yield
46 (0.16 g, 40%) as a yellow oil and 3,4-dimethyl-1-[1-(1-oxoethyl)-
2-oxoprop-1-en-1-yl]benzene (49, 0.12 g, 30%) as a yellow solid,
dimethyl), 1.78 (s, 6 H, CH3-Cϭ), 4.83Ϫ4.84 [ps-s, 2 H, ϭCH2, m.p. 66Ϫ68 °C.
Table 1. Details of X-ray structure analyses of 25, 31 and 32
Compound
25
31
32
Empirical formula
Mr
Habit
C25H20
320.41
yellow prism
0.9 ϫ 0.7 ϫ 0.3
monoclinic
P21/c
C19H28Si2
312.59
colorless prism
0.5 ϫ 0.3 ϫ 0.2
monoclinic
Cc
C28H44Si4
492.99
pale yellow prism
0.5 ϫ 0.35 ϫ 0.2
triclinic
Crystal size [mm]
Crystal system
Space group
Cell constants:
¯
P1
˚
a [A]
18.8564(15)
7.0844(6)
14.1230(11)
90
94.980(6)
90
1879.5
4
1.132
0.06
9.481(2)
24.975(6)
8.893(2)
90
92.28(2)
90
2104.2
4
0.987
0.16
6.431(2)
9.809(3)
13.241(4)
74.67(2)
82.50(2)
79.42(2)
0.7889
1
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
3
˚
V [A ]
Z
Dx [Mg mϪ3
]
1.038
0.20
268
µ [mmϪ1
F(000)
]
680
680
T [°C]
Ϫ100
50
Ϫ130
50
Ϫ130
50
2θmax [°]
No. of reflections:
measured
independent
Rint
Parameters
Restraints
wR(F2, all refl.)
R[F Ͼ 4σ(F)]
S
4215
3311
0.016
228
3691
3221
0.023
198
2832
2781
0.013
151
0
133
0
0.088
0.036
0.90
0.15
0.099
0.039
1.06
0.18
0.120
0.050
1.04
0.25
Ϫ3
˚
max. ∆ρ [e A
]
Eur. J. Org. Chem. 2002, 1708Ϫ1721
1719

H. Hopf, J. Kämpen, P. Bubenitschek, P. G. Jones
FULL PAPER
a) Compound 46: H NMR (400 MHz, CDCl3): δ ϭ 1.15 (s, 6 H,
Engl. 1995, 34, 2367Ϫ2368. [1b] Part IV: H. Hopf, U. Hamann,
1
3
G. Zimmermann, D. Remmler, J. Pure Appl. Pyrolysis 1994,
gem-dimethyl), 2.35 (s, 6 H, CH3-CO), 6.25 (ps-d, J1-H,2-H
ϭ
[1c]
29, 57Ϫ63.
Part III: H. Hopf, M. Kreutzer, P. G. Jones,
3J4-H,5-H ϭ 10.3 Hz, 2 H, 1-H/5-H), 6.68 (ps-d, J1-H,2-H
ϭ
3
Angew. Chem. 1991, 103, 1148Ϫ1149; Angew. Chem. Int. Ed.
Engl. 1991, 30, 1127Ϫ1128.
3J4-H,5-H ϭ 10.3 Hz, 2 H, 2-H/4-H). 13C NMR (100 MHz, CDCl3):
δ ϭ 27.7 (gem-dimethyl), 31.8 (CH3-CO), 37.9 (C-6), 120.9 (C-2/C-
4), 135.2 (C-7), 136.9 (C-3), 148.5 (C-1/C-5), 201.2 (CϭO). IR
(film): ν˜ ϭ 3002 cmϪ1 (w), 2966 (m), 2942 (m), 2926 (m), 2870 (w),
1696 (s), 1672 (s), 1639 (s), 1538 (s), 1471 (m), 1411 (m), 1394 (m),
1357 (s), 1329 (m), 1289 (m), 1214 (s), 1192 (s), 1168 (m), 928 (m),
820 (s), 698 (m). UV/Vis (methanol): λmax (lg ε) ϭ 204 nm
(3.81), 310 (4.23). MS (EI): m/z (%) ϭ 204 (69) [Mϩ], 189 (100),
161 (73), 143 (50), 128 (18), 115 (30), 105 (22), 91 (34), 77 (25), 55
(69), 43 (99). HRMS (C13H16O2): calcd. 204.115; found 204.115
Ϯ 3 ppm.
[2]
[3]
T. L. Cairns, R. A. Carboni, D. D. Coffman, V. A. Engelhardt,
R. E. Heckert, E. L. Little, E. G. McGreer, B. C. McKusick,
W. J. Middleton, J. Am. Chem. Soc. 1957, 79, 2340Ϫ2341.
The first comprehensive study on the preparation and chemical
properties of 1 appeared only a year later in a remarkable series
of twelve consecutive papers, J. Am. Chem. Soc. 1958, 80,
2775Ϫ2844, which are still a pleasure to read.
R. E. Merrifield, W. D. Phillips, J. Am. Chem. Soc. 1958, 80,
2778Ϫ2782; cf.: L. R. Melby in Z. Rappoport (Ed.), The Chem-
istry of the Cyano Group, Interscience Publishers, London,
1970, chapter 10, p. 639Ϫ669.
[4]
[5]
1
b) Compound 49: H NMR (400 MHz, CDCl3): δ ϭ 1.89 (s, 6 H,
The chemistry of 1 has been reviewed many times; for a selec-
tion see: [5a] E. Ciganek, W. J. Linn, O. W. Webster in Z. Rappo-
port (Ed.), The Chemistry of the Cyano Group, Interscience
2 ϫ CH3-CO), 2.27 (s, 3 H, CH3-ar), 2.28 (s, 3 H, CH3-ar), 6.88
3
4
(dd, J5-H,6-H ϭ 7.6, J2-H,6-H ϭ 1.7 Hz, 1 H, 6-H), 6.93 (s, 1 H, 2-
H), 7.13 (d, J5-H,6-H ϭ 7.6 Hz, 1 H, 5-H), 16.64 (s, 1 H, OH). 13C
3
Publishers, London, 1970, chapter 9, p. 423Ϫ638. [5b] A. J. Fati-
[5c]
NMR (100 MHz, CDCl3): δ ϭ 19.4 (CH3-ar), 19.7 (CH3-ar), 24.1
(CH3-CO), 115.1 (C-7), 128.4 (C-6), 129.9 (C-5), 132.1 (C-2), 134.3
(C-1), 135.7 (C-3), 136.9 (C-4), 191.0 (CϭO). IR (KBr): ν˜ ϭ 3022
cmϪ1 (w), 2974 (m), 2943 (m), 2920 (m), 1713 (m), 1608 (s), 1504
(s), 1449 (s), 1400 (s), 1333 (s), 1285 (m), 1235 (m), 1129 (m), 1020
(m), 985 (s), 920 (m), 892 (w), 863 (m), 821 (m). UV/Vis (methanol):
λmax (lg ε) ϭ 204 nm (4.25), 288 (3.90). MS (EI): m/z (%) ϭ 204
(100) [Mϩ], 189 (83), 161 (75), 143 (41), 128 (21), 115 (31), 91 (23),
77 (16), 55 (66). C13H16O2 (204.3): calcd: C 76.44, H 7.90, O 15.67;
found C 76.36 H 7.83 O 15.72.
adi, Synthesis 1986, 249Ϫ284.
R. Dworczak, H. Junek, in
The Chemistry of Triple-bonded Functional Groups, Supplement
C2 (Ed.: S. Patai), J. Wiley and Sons, Chichester, 1994, chapter
14, p. 789Ϫ871.
D. S. Acker, W. R. Hertler, J. Am. Chem. Soc. 1962, 84,
3370Ϫ3374.
[6]
[7]
[8]
J. Ferraris, D. O. Cowan, V. Walatka, Jr., J. H. Perlstein, J. Am.
Chem. Soc. 1973, 95, 948Ϫ949.
[8a]
For a summary of the early literature see:
A. F. Garito, A.
J. Heeger, Acc. Chem. Res. 1974, 7, 232Ϫ240. [8b] F. Wudl, Acc.
Chem. Res. 1984, 17, 227Ϫ232.
[9]
X-ray Structure Determinations: Numerical details are presented in
Table 1. Data collection and reduction: Crystals were mounted in
inert oil on glass fibers and transferred to the cold gas stream of
the diffractometer (31, 32: Stoe STADI-4; 25: Siemens P4; both
with Siemens LT-2 low-temperature system). Measurements were
performed with monochromated Mo-Kα radiation. Cell constants
were refined from Ϯω angles (Stoe) or setting angles (Siemens) of
ca. 60 reflections to 2θ ϭ 23°. Structure solution and refinement:
The structures were solved by direct methods and refined aniso-
tropically against F2 (program SHELXL-97: G.M. Sheldrick, Uni-
versity of Göttingen). H atoms were included with a riding model
or with rigid methyl groups. For compound 31, the absolute struc-
ture was determined by an x refinement: x ϭ 0.01(13); to improve
stability of refinement, a system of restraints to displacement
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Acknowledgments
We thank Prof. Dr. L. Ernst (Technical University of
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