Studies in the cycloproparene series: Cross-conjugated π-extended alkylidenecycloproparenes

Article abstract of DOI:10.1002/ejoc.200400353

The first simple and stable cross-conjugated π-extended alkylidenecycloproparenes 5, 6 and 15-22 have been prepared as coloured crystalline derivatives from use of (E,E)-1,5-diphenylpenta-2,4-dienone, (E,E)-1,5-diarylpenta-1,4-dien-3-ones and (E,E)-2,5-(d

Full text of DOI:10.1002/ejoc.200400353

FULL PAPER
Studies in the Cycloproparene Series: Cross-Conjugated π-Extended
Alkylidenecycloproparenes
G. M. Dixon[a] and B. Halton*[a]
Keywords: Small ring systems / Arenes / Hydrocarbons / Peterson olefination / Strained molecules / Dipole moments
The first simple and stable cross-conjugated π-extended al-
kylidenecycloproparenes 5, 6 and 15−22 have been prepared
as coloured crystalline derivatives from use of (E,E)-1,5-di-
phenylpenta-2,4-dienone, (E,E)-1,5-diarylpenta-1,4-dien-3-
ones and (E,E)-2,5-(diarylmethylidene)cyclopentanones with
the relevant 1,1-bis(trimethylsilyl)cyclopropa[b]naphthalene.
The permanent dipole moments of the compounds have
been measured, and the conformational preference of the
rotamers assessed.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
rivative, which facilitates unimpeded mesomeric π-orbital
overlap; the twist in the diaryl derivatives is about 30°.[1,15]
This rotation of the double-bond substituents in the exo-
cyclic alkylidenecycloproparenes is less than that in
analogous penta- and heptafulvenes,[16Ϫ20] simply because
there is a significant volume of free space adjacent to the
external three-membered ring σ-bonds Ϫ after all, the mol-
ecules can be regarded as much as 1,6-didehydrohepta-
fulvenes as cycloproparenes. Nevertheless, each rotated aryl
substituent gives rise to a vector component to the dipole
that contributes about 80%. Furthermore, the effect from
both aryl substituents is to combine and give a net dipole
that is only about 1.6 times higher than that of the
monoaryl analogue. In order to provide for an unequivocal
enhanced contribution to the polarity in the disubstituted
derivatives, essentially the simplest possible conjugating
spacer groups have been incorporated from use of the
(E,E)-1,5-diarylpenta-1,4-dien-3-ones 7Ϫ14.
The alkylidenecycloproparenes, for example 3[1] and 4,[2]
have continued to provide a source of fascination[3,4] since
their discovery in 1984,[5] not least because the various de-
rivatives have unexpected polarities,[6Ϫ8] fluorescence
characteristics[9] and novel properties.[10Ϫ12] Recently, we
described the preparation of a series of conjugated and
cross-conjugated cycloproparene derivatives containing
cyclopentadiene and dithiole subunits. In the main, these
compounds are disappointing in that they have limited life-
times under normal laboratory conditions and are obtained
from low-yielding syntheses that has thwarted their possible
use in the new organic materials area.[13] Undeterred by
these features, we sought to obtain less complex derivatives
in the hope that extended conjugation by way of simple
substituted π-bonds would provide stable, but more polar
derivatives, which can be physically examined. We now de-
scribe the 1-pentadienylidene compounds 5 and 6, and the
series of coloured, crystalline 3Ј-pentadienylidene deriva-
tives 15Ϫ22 that are stable compounds with enhanced polar Results and Discussion
character relative to their methylidene homologues and
have a conformational preference that matches those of
their dienone precursors 7Ϫ14.
Commercially available (E,E)-1,5-diphenylpenta-2,4-di-
enone (5-phenylpenta-2,4-dienophenone) successfully reacts
The recorded polarities of a number of 1H-alkylidenecy- with the α-silyl anion formed upon reaction of the disilanes
cloproparenes are unambiguous in that they show that a 1 and 2 with tBuOK[1,5,10] to yield the alkylidenecyclopro-
single exocyclic aryl substituent gives rise to a molecule parenes 5 and 6 in yields of 50 and 20%, respectively
whose polarity is more than half that of the corresponding (Scheme 1). By adding the pentadienone to a THF solution
diaryl derivative.[6,10,14,15] This stems from the minimal de- of preformed α-silyl anion at Ϫ70 °C, the yield of the exo-
gree of twist of the aryl substituent from the plane contain- cyclic alkene is better than the reaction in which the anion
ing the cycloproparene moiety (0Ϫ5°) in the monoaryl de- is formed at the same temperature but in the presence of
the conjugated dienenone, by a factor of about 3; in all
[a]
likelihood competing conjugate addition is minimised. The
spectral characteristics of 5 and 6 are fully compatible with
the unsymmetrical substitution pattern at the exocyclic cen-
tre C-8. Thus, the cycloproparenyl 2-H and 7-H protons
School of Chemical & Physical Sciences, Victoria University
of Wellington,
P. O. Box 600, Wellington, New Zealand
Fax: (internat.) ϩ 644-463-5241
E-mail: brian.halton@vuw.ac.nz
Eur. J. Org. Chem. 2004, 3707Ϫ3713
DOI: 10.1002/ejoc.200400353
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3707

G. M. Dixon, B. Halton
FULL PAPER
resonate as para-coupled doublets (J ഠ 1.7 Hz), and the from the dibenzylideneacetones (ketocyanines) 7Ϫ11 in
(E,E) stereochemistry of the dienylidene subunit is demon- yields that range from 32 to 82%; the compounds are stable
strated by a characteristic Jtrans coupling of 16 Hz. The 13C crystalline solids whose dipole moments have been meas-
NMR spectra differentiate between the sides of the cyclo- ured and have the values shown in Scheme 1. The known
proparenyl moiety oriented (E) and (Z) with respect to the (E,E)-ketocyanines 7Ϫ11 were obtained, in turn, from base-
exocyclic dienylidene subunit (Exp. Sect.), and C-2/C-7 are induced double condensation of the appropriate benzal-
markedly more shielded[10] in 6 (δ ϭ 101.8 and 101.9 ppm) dehyde with acetone [Equation (1)] using the procedure of
than in 5 (δ ϭ 106.9 ppm) due to the spatially proximal Olomucki and Le Gall.[23] Aldehydes carrying p-CN, p-CF3
OMe functions. As expected,[21] 5 and 6 (1.38 and 1.88 D) and p-NO2 electron-withdrawing functionalities failed to
are more polar than the diphenyl congeners 3 and 4 (0.44 give a product from this reaction that employs sodium hy-
and 1.19 D), respectively; HF/6-31G** calculations predict droxide as the base. The reasons for this are not clear, given
that the direction of the dipole lies from the cycloproparene that these same aldehydes react in Peterson olefinations
moiety toward the exocyclic substituents. The fact that the with the α-silyl anions derived from 1 and 2 upon treatment
diethers 4[2] and 6 have an increased dipole moment relative with tBuOK. In addition, the conformationally locked
to their non-ether counterparts 3[6] and 5, respectively,[21] cycloproparenes 20Ϫ22 have also been prepared by em-
provides further experimental verification that the cyclopro- ploying the 2,5-dimethylidenecyclopentanones 12Ϫ14 as
pa[b]naphthalenyl moiety is an electron donor. The degree substrates.[24] Each of the cycloproparene derivatives is ex-
of twisting of the terminal (C-5Ј) phenyl groups in 5 and 6 pected to carry the pendant aryl groups twisted to a com-
mirrors those in simple (E)-stilbenes[22] in that the twist parable extent with that in the precursor ketone.
angle is about 18°. Moreover, conformational searching
using the SPARTAN molecular mechanics program locates
the (E,E) isomer of 5 in the elongated s-trans,s-trans form
(1)
(as drawn) as the energy minimum, while the 18° twist (di-
hedral) angle of the C-5Ј terminal phenyl group is provided
from the HF/6-31G** equilibrium geometry; the C-1 phe-
Spectroscopic analysis of the ketones 7Ϫ14 and the
nyl group is essentially nonconjugated as it is rotated almost cycloproparene products 15Ϫ22 provide data that are fully
90° out of the plane of the cycloproparene.
consistent with the proposed structures (Exp. Sect.). For
cycloproparenes 15Ϫ22, the singlet nature of 2-H/7-H, the
AAЈBBЈ pattern for 3-H/6-H and the shielding of C-2/C-7
in the 13C spectrum (δ ϭ 106Ϫ108 ppm) is as expected,[4,10]
while the configuration about the alkenyl spacer groups is
confirmed as (E,E) from the proton-proton spin-spin coup-
lings of about 16 Hz in the alkenyl proton doublets of 9-H/
10-H and 9Ј-H/10Ј-H (Exp. Sect.).
While the olefin stereochemistries are readily assigned
(E,E), the NMR spectroscopic data do not provide infor-
mation about the spatial arrangement of the side chains in
either the ketocyanines 7Ϫ14 or the derived alkylidenecy-
cloproparenes 15Ϫ22. Quite recently, the solution conform-
ers of p,pЈ-(diethylamino)phenylketocyanine 23 have re-
ceived attention.[25,26] The two degrees of rotational free-
dom imposed by the two carbonϪcarbonyl single bonds
provide for the three planar rotamers of Figure 1. These
were predicated by Marcotte and FeryϪForgues as energy
minima with energies (∆Hf) from AM1 calculations of
170.6 (s-cis,s-cis), 175.8 (s-cis,s-trans) and 181.6 (s-trans,s-
trans) kJ·molϪ1, respectively.[25] The higher energy s-trans,s-
trans conformer has alkene hydrogen atoms in spatial con-
flict (Figure 1) and is unlikely to be found in solution, not
simply because it is most disfavoured thermodynamically,
but because of the 11 kJ·molϪ1 energy barrier that separates
it from the lowest energy form.[25] The fully planar s-cis,s-cis
conformer gains its 6 kJ·molϪ1 stabilization from hydrogen
bonding (Figure 1), but the s-cis,s-trans rotamer becomes
the most stable when one of the terminal aryl groups is
Scheme 1
In order to provide cycloproparenes with more appropri- twisted by 30° with respect to the plane of the molecule;
ate π-extended cross-conjugated substituents, the symmetri- parent dibenzylideneacetone (7) is similar, as has been dis-
cal pentadienylidene derivatives 15Ϫ19 have been prepared cussed.[27] For comparative purposes, Marcotte and Fery-
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Cross-Conjugated π-Extended Alkylidenecycloproparenes
FULL PAPER
Figure 2. Vector analysis of the partial dipoles of the rotamers of
ketocyanine 23
Figure 1. The stable rotamers 1,5-diarylpenta-2,4-dien-3-ones 7Ϫ11
pole moments (Figure 2), and assuming a twist of about
30° for each aryl substituent as is the case for the cyclopro-
parenes,[1,10,15] the s-trans,s-trans rotamer should be the
most polar isomer with a dipole moment of approximately
6.4 D.[29] The transfer of electron density from ‘‘source’’
to ‘‘sink’’ effectively renders the inductive dipole moment
negligible so that the observed dipole will be that caused by
mesomeric phenomena.
Forgues also performed AM1 calculations on the confor-
mationally locked analogue of 23, namely (E,E)-2,5-bis(p-
diethylaminophenyl)methylidenecyclopentanone (24), as it
has no rotational freedom about the carbonylϪalkene sin-
gle bonds.[25] The conjugated system of 24 is predicted to
be virtually planar and, since such ‘‘locked’’ ketocyanines
are readily available from cyclopentanone by the procedure
used to prepare 7Ϫ11, ketones 12Ϫ14 have also been pre-
pared by us (Exp. Sect.)[23] and transformed into the cyclo-
proparene derivatives 20Ϫ22 (Scheme 1).
The conformationally ‘‘locked’’ cycloproparenes 20Ϫ22
(prepared from cyclopentanones 12Ϫ14) comprising para-
methyl, -methoxy and -dimethylamino substituents have
measured dipole moments of 1.73, 2.91 and 3.51 D, respec-
tively (Table 1). Each ‘‘locked’’ molecule carries a noncon-
jugating ethano bridge and, as such, is an appropriate
mimic for the ‘‘pure’’ s-cis,s-cis rotamer of the correspond-
ing ‘‘loose’’ homologues 16Ϫ18. These last compounds are
found to be more polar [µ ϭ 2.07, 3.38, and 4.23 D, respec-
tively (Table 1)] and therefore, they cannot be present ex-
clusively in the s-cis,s-cis form; a significant contribution to
each dipole must come from the s-cis,s-trans rotamer. As
each dipole moment was measured in benzene solution, the
rotamer distribution should agree with the IR measure-
ments in toluene rather than in acetonitrile.[30] Thus, with
the use of the AM1-calculated dipoles of the s-cis,s-cis and
s-cis,s-trans rotamers of (diethylamino)ketocyanine 23 with
a ratio of 23:77 in toluene (IR), the solution dipole for the
rotameric mixture of 23 is computed as 5.05 D, viz. (0.23
ϫ 4.2) ϩ (0.77 ϫ 5.3) D; this is in good agreement with
that measured by us for the bis(dimethylamino) analogue
10 (5.16 D) in benzene. Here, it should be noted that meas-
urement of the dipole moments for equivalent dimethyl-
amino- and diethylamino-substituted alkylidenecyclo-
Infrared studies on dienone 23 in acetonitrile show[25]
two CϭO bands at approximately 1660 and 1640 cmϪ1 in
a ratio of 11:89, while in toluene the bands are at 1664
and 1646 cmϪ1 and have a ratio of 23:77. Distinct carbonyl
stretches for the different conformers are to be expected and
fit well with results of Venkateshwarlu and Subrahman-
yam[28] who have shown that 7 (Ar ϭ Ph) (and many other
α,β-unsaturated ketones) has a CϭO band of the s-cis,s-cis
conformer as the weaker signal (at higher cmϪ1) and about
21 cmϪ1 from that of the s-cis,s-trans rotamer in CCl4.
Thus, the 20 cmϪ1 separation and peak intensities recorded
for 23 are fully compatible with the finding that the s-cis,s-
trans rotamer [ν˜ ϭ 1640 cmϪ1] strongly dominates in solu-
tion. Furthermore, the only IR carbonyl frequency re-
corded for the s-cis,s-cis-locked analogue 24 lies close to the
weaker band of 23. The conformational characteristics of
Table 1. Experimental dipole moments (benzene solution) of cyclo-
the ketocyanines 7Ϫ11 should be mirrored by the derived proparenes 12Ϫ14 and 16Ϫ18
alkylidenecyclopropa[b]naphthalenes 15Ϫ22, but without
any stabilizing ϾCϭO···H interactions. As these last com-
pounds have no characteristic intense IR absorption bands
(only weak stretches[3] occur in the range 1760Ϫ1790
cmϪ1), conformational information is not easily deduced
from IR studies. However, it is possible to obtain estimates
of the rotamer distributions in the alkylidenecyclopropar-
enes from use of their measured dipole moments and those
R
‘‘Locked’’: µ [D]
‘‘Loose’’: µ [D]
of appropriate model compounds.
The s-cis,s-trans and s-cis,s-cis rotamers of ketone 23 have
dipole moments that have been calculated as 5.3 and 4.2
D, respectively; the nonbonding electron pairs extend the
conjugation.[25] By applying the vector model for partial di-
Me
OMe
NMe2
20: 1.73
21: 2.91
22: 3.51
16: 2.07
17: 3.38
18: 4.23
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G. M. Dixon, B. Halton
FULL PAPER
propanaphthalenes is the same within experimental uncer- evident for 18 (shoulders at 435, 448 and 485 nm; Exp.
tainty, for example 8,8-diphenylmethylidene: NEt2 2.9 D, Sect.) is lost in acetonitrile and, in comparison with the
NMe2 3.0 D[31] and 1,4-dimethoxy-8,8-diphenylmethylid- cyclopentano ‘‘locked’’ derivatives 20Ϫ22 (also nonfluor-
ene: NEt2 2.3 D, NMe2 2.3 D.[14] On the reasonable escent), the ‘‘loose’’ analogues 16Ϫ18 have longer wave-
assumption that the geometries of the s-cis,s-cis and s-cis,s- length absorption maxima. This reflects the dominance of
trans rotamers of 15Ϫ19 are similar to those of 23, and that the s-cis,s-trans conformer in solution as shown by both
the ‘‘locked’’ compounds 20Ϫ22 are suitable models for the experiment and theory. The chemistry and photochemistry
s-cis,s-cis rotamers of 16Ϫ18, the proportions of s-cis,s- of these novel compounds remains to be explored.
trans conformer in benzene solutions of 16Ϫ18 are esti-
mated to lie in the range 60Ϫ80%.[32] Thus, the dipole mo-
ment determinations lead to entirely plausible rotamer dis-
tributions for 16Ϫ18 that conform with those of their keto Experimental Section
progenitors 8Ϫ10.
General: Microanalyses were performed by the Analytical Facility
Each of the pentadienylidene derivatives 15Ϫ19 has a di-
of Otago University, Dunedin. Low-resolution electron impact
pole moment that is greater than its methylidene analogue
mass spectra were recorded with a Hewlett Packard HP-5995C in-
and in a direction given by 6-31G** calculations (Table 2).
strument at 70 eV. APCI mass spectrometry and accurate mass
This applies whether the cycloproparene is the electron do-
measurements were carried out by Mr. Oleg Zubkov with a PE
nor or the electron acceptor. However, the additional conju-
gation provided by the unencumbered π-bond cannot be
presumed to increase polarity in a uniform manner. The
6-31G** calculations show a conformational preference of
Biosystem Mariner 5158 TOF mass spectrometer. 1H and 13C
NMR spectra were recorded with a Varian Unity-INOVA 300 spec-
trometer, operating at 300 and 75 MHz, respectively, for [D]chloro-
form solutions using the residual solvent peak as internal standard.
15Ϫ18 for the s-cis,s-trans rotamer and provide equilibrium 1H NMR multiplicities are defined by the usual notation; coupling
constants, J, are specified in Hz. The assignments of 13C and 1H
geometries in which the s-trans π-bond and its terminal aryl
NMR resonances were made with the aid of distortionless enhance-
ring are held close to the plane of the cycloproparene for
1
ment by polarisation transfer (DEPT) and H-1H and 13C-1H cor-
effective π-overlap, whereas the s-cis π-moiety is rotated by
about 40° and its attendant aryl group by a further 20°.
relation spectroscopy (COSY) experiments, and confirmed from
heteronuclear multiple bond connectivity (HMBC) and heteronu-
clear single quantum correlation (HSQC) experiments. Assign-
ments are based on the numbering system in Scheme 1 which does
Table 2. Experimental dipole moments (benzene solution) of alkyl-
not correspond with the nomenclature of the compound names.
Infrared spectra were recorded for KBr disks with a Biorad FTS-7
spectrophotometer (Ϯ2 cmϪ1). Ultraviolet/visible (UV/Vis) spectra
were acquired with a HewlettϪPackard 8452A diode array spectro-
photometer in quartz cells (Ϯ1 nm). Melting points were deter-
mined with a Reichert hot-stage melting-point apparatus and are
uncorrected. Thin layer chromatographic (TLC) analyses were per-
formed using Merck Kieselgel (Alufolien) 60 F254 to a thickness of
0.2 mm. Components were detected under UV light (254 or
350 nm), or by spraying with 1:1 MeOH/H2SO4 (concd.), followed
by heating. Radial chromatography was performed with a Chroma-
totron 9724T instrument (Harrison Research, Palo Alto, Cali-
fornia) at 90 rpm. Rotors were coated with gypsum-containing
Merck Kieselgel 60 DGF254 to thicknesses of 1.0, 2.0, 3.0 or
4.0 mm, and the total mass of solute loaded onto the plate was
0.25, 0.75, 1.15 and 1.5 g, respectively. Solvents were purified before
use according to Perrin, Aramarego and Perrin.[33] The light petro-
leum used was the hexane fraction, b.p. 60Ϫ70 °C. Anhydrous
tetrahydrofuran (THF) was obtained by distillation immediately
prior to use from a dark blue-purple solution of sodium/potassium
benzophenone ketyl.
idenecyclopropa[b]naphthalenes
R
Methylidene Orientation 3Ј-Pentadienylidene Orientation
µ [D]
µ [D]
[a]
H
Me
0.44
Ϫ
ȇ
Ȇ
Ȇ
Ȇ
ȇ
15: 1.12
16: 2.07
17: 3.38
18: 4.23
19: 1.38
ȇ
Ȇ
Ȇ
Ȇ
ȇ
OMe 2.40[b]
NMe2 3.00[c]
F
0.87
[a]
This work and ref.[6] [b] Datum taken from ref.[6] [c] Datum taken
from refs.[7,15]
Dipole Moment Measurements: Dipole moments were determined
for AnalaR grade benzene solutions (ca. 0.05Ϫ0.10 ) by the
method of Guggenheim[34] and Smith,[35] using a small (ca. 2 mL)
variable capacitance cell with analytically pure (C, H) compounds.
Impedance readings were taken with the cell open and closed em-
ploying a HewlettϪPackard 913 vector impedance meter operating
at 1 MHz. The recordings were taken at ambient temperature. Re-
fractive index measurements were made with an Abbe 60 Refrac-
tometer. Benzophenone, diphenyl sulfone, and 2-hydroxynaphtha-
lene were used as reference standards, against which the reproduc-
The highly coloured compounds 15Ϫ17 and 19 have
UV/Vis absorption bands in the range 470Ϫ500 nm as ex-
pected from incorporation of the two conjugating spacer
units into the lower methylidene homologues. Bis(dimethyl-
amino) compound 18 (λmax. ϭ 466 nm) is the exception as
it is not fluorescent like is its lower homologue.[9,15] Most
likely, the two ethene spacers that extend the conjugation
move the aryl rings too far from the cycloproparene moiety
for effective electron transfer and formation of a twisted
internal charge transfer (TICT) state.[9] The fine structure ibility of the cell was verified before and after each series of meas-
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Eur. J. Org. Chem. 2004, 3707Ϫ3713

Cross-Conjugated π-Extended Alkylidenecycloproparenes
FULL PAPER
urements. Dipole moments were calculated by employing
a
1-(1,5-Diphenylpenta-2,4-dien-1-ylidene)-3,6-dimethoxy-1H-cyclo-
Microsoft Excel spreadsheet; values were rounded to 2 decimal propa[b]naphthalene (6): Disilane 2[2] (100 mg, 0.29 mmol) and 5-
points at the end of the algorithm only.
phenyl-2,4-pentadienophenone (340 mg, 1.45 mmol) gave an or-
ange solid, and by radial chromatography [light petroleum/di-
chloromethane (4:1) elution] title compound 6 was obtained. Yield:
28 mg (23%). Orange needles (light petroleum), m.p. 136.0Ϫ137.5
°C. 1H NMR (300 MHz, CDCl3): δ ϭ 3.96 (s, 6 H, OMe), 6.67 (d,
3Jtrans ϭ 15.4 Hz, 1 H, 12-H), 6.76 (s, 2 H, 4-H/5-H), 7.08Ϫ7.14
(m, 2 H, 10-H and 11-H), 7.22Ϫ7.24 (m, 2 H, 21-H/23-H),
7.33Ϫ7.38 (m, 3 H, 9-H, 16-H and 22-H), 7.46Ϫ7.53 (m, 4 H, 15-
H/17-H and 20-H/24-H), 7.78Ϫ7.81 (m, 2 H, 14-H/18-H), 7.92 (d,
Jpara ϭ 1.7 Hz, 1 H, 2-H or 7-H) 8.01, d, Jpara ϭ 1.7 Hz, 1 H, 7-H
or 2-H) ppm. 13C NMR (75 MHz, CDCl3): δ ϭ 55.9 (OMe), 101.8
(C-2 or C-7), 101.9 (C-7 or C-2), 104.5 (C-4/C-5), 113.0 (C-1), 117.5
(C-8), 126.4 (C-20/C-24), 127.3 (C-16), 127.4 (C-21/C-23), 127.6
(C-1a or C-7a), 127.9 (C-7a or C-1a), 128.6 (C-15/C-17), 128.7 (C-
14/C-18), 130.1 (C-9), 130.5 (C-10), 131.3 (C-2a or C-6a), 131.4 (C-
6a or C-2a), 132.1 (C-11), 132.2 (C-12), 137.7 (C-19), 138.5 (C-13),
150.5 (C-3/C-6) ppm. HRMS (positive APCI): calcd. for C30H25O2
[M ϩ H]ϩ 417.1254; found 417.1255 (ϩ0.25 mmu). MS (70 eV): m/
z (%) ϭ 417 (11) [M ϩ 1]ϩ, 416 (32) [M]ϩ, 401 (14), 385 (75), 86
(53), 84 (73), 57 (45), 56 (43), 51 (42), 49 (100). IR (KBr): ν˜ ϭ
2965, 2933, 2830, 2172, 1773 (w), 1613, 1462, 1325, 1260, 1223,
1170, 1103, 1070, 1005, 796, 699 cmϪ1. UV/Vis (cyclohexane): λmax.
(log ε) ϭ 228 (4.12), 304 (4.21), 336 (4.30), 456 nm (4.31). UV/Vis
(acetonitrile): λmax.(log ε) ϭ 224 (4.15), 304 (4.24), 334 (4.29),
454 nm (4.27). Dipole moment (benzene): µ (20 °C) ϭ 1.88 D.
Dipole Moments µ: 3[1,6] (benzene, 21 °C) 0.44 D; 4[2,14] 1.19 D;
10[14] (benzene, 21 °C) 5.16 D.
(E,E)-1,5-Diarylpenta-1,4-dien-3-ones 7؊11: The known benzylid-
eneacetones 7,[23] 8,[36] 9,[37] 10[38] and 11[39] were prepared from
acetone (0.59 g, 0.92 mL, 0.0125 mol) and the relevant benzal-
dehyde (0.025 mol) in alkaline medium by the procedure of Olo-
mucki and Le Gall.[23] The crude products, rinsed with cold ethanol
and purified by flash column chromatography on silica (about
10 g), were used directly.
(E,E)-2,5-(Diarylmethylidene)cyclopentanones
12؊14:
The
‘‘locked’’ ketocyanines 12Ϫ14 were prepared as described by
Kaupp and co-workers,[24] by condensing the relevant benzaldehyde
(0.025 mol, 3.72 g) with cyclopentanone (0.0125 mol, 1.05 g,
1.00 mL) in the presence of approximately 40 mol % of benzyltri-
methylammonium hydroxide in methanol. The crude products were
rinsed with cold ethanol and purified by flash column chromatog-
raphy on silica (about 10 g).
Alkylidenecycloproparenes 5 and 6: A solution of freshly sublimed
potassium tert-butoxide (5 equiv.) in THF (about 10 mL) was ad-
ded dropwise by a syringe needle to a stirred solution of disilane[15]
1 (1 equiv.) in anhydrous tetrahydrofuran (approximately 10 mL)
held at Ϫ70 °C under nitrogen. The mixture was stirred at Ϫ70 °C
for 30 min, by which time a deep red colour had developed. To this
was added a solution of the carbonyl compound (5 equiv.) in THF
(about 10 mL), stirring continued at Ϫ70 °C for a further 1 h, and
then the cryostat was switched off, and the mixture left to warm to
ambient temperature overnight. The mixture was quenched
(NaHCO3 satd., 30 mL), the organic products were extracted with
dichloromethane (3 ϫ 20 mL), and the organic solution was
washed with water (3 ϫ 20 mL), dried (MgSO4, about 2 g), filtered
and concentrated under reduced pressure to give a crude product
that was purified by radial chromatography.
Alkylidenecycloproparenes 15؊22 and Bis[p-(fluorophenyl)methyl-
idene]cyclopropanaphthalene: The method described above for 5 and
6 was employed with the notable exception that stoichiometric
quantities of base (0.035 mmol) and carbonyl compound (0.35 mmol)
led to optimum conversion.
(E,E)-1-(1,5-Diphenylpenta-1,4-dien-3-ylidene)-1H-cyclopropa[b]-
naphthalene (15): Light petroleum/dichloromethane (6:1) elution
gave title compound 15. Yield: 40 mg (32%). Yellow flakes (light
petroleum), m.p. 106.5Ϫ108.0 °C. 1H NMR (300 MHz, CDCl3):
δ ϭ 7.21 (d, 3Jtrans ϭ 16.0 Hz, 2 H, 9-H), 7.29 (d, 3Jtrans ϭ 16.0 Hz,
2 H, 10-H), 7.30Ϫ7.35 (m, 6 H, 14-H and 13-H/15-H), 7.47Ϫ7.50
(m, 4 H, 4-H/5-H and 2-H/7-H), 7.60 (d, 3JAB ϭ 8.5 Hz, 4 H, 12-H/
16-H), 7.87Ϫ7.90 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H) ppm. 13C NMR
(75 MHz, CDCl3): δ ϭ 107.3 (C-2/C-7), 112.7 (C-1), 115.8 (C-8),
124.2 (C-9), 127.1 (C-4/C-5), 127.4 (C-12/C-16), 127.6 (C-1a/C-7a),
128.1 (C-10), 128.6 (C-13/C-15), 128.7 (C-3/C-6), 128.8 (C-14),
137.7 (C-11), 139.2 (C-2a/C-6a) ppm. IR (KBr): ν˜ ϭ 2971, 2928,
2327, 2174, 1774 (w), 1717, 1654, 1563, 1508, 1176, 1144, 1035, 875
cmϪ1. UV/Vis (cyclohexane): λmax. (log ε) ϭ 306 (3.46), 328 (3.51),
356 (3.66), 476 nm (4.01). UV/Vis (acetonitrile): λmax. (log ε) ϭ
306 (3.47), 326 (3.45), 354 (3.62), 472 nm (3.97). Dipole moment
(benzene): µ (21 °C) ϭ 1.12 D. C28H20 (356.47): calcd. C 94.34, H
5.66; found C 94.42, H 5.58.
1-(1,5-Diphenylpenta-2,4-dien-1-ylidene)-1H-cyclopropa[b]-
naphthalene (5): Disilane 1[15] (100 mg, 0.35 mmol) and 5-phenyl-
2,4-pentadienophenone (410 mg, 1.75 mmol) gave a bright orange
solid and by radial chromatography [light petroleum/dichlorometh-
ane (2:1) elution] title compound 5 was obtained. Yield: 62 mg
(50%). Dark red microcrystals (light petroleum), m.p. 182.0Ϫ183.0
1
3
°C. H NMR (300 MHz, CDCl3): δ ϭ 6.67 (d, Jtrans ϭ 17.0 Hz, 1
H, 12-H), 6.95Ϫ7.25 (m, 4 H, 9-H, 16-H, 20-H/24-H), 7.33Ϫ7.43
(m, 4 H, 10-H, 21-H/23-H, 22-H), 7.46Ϫ7.58 (m, 7 H, 4-H/5-H, 2-
3
H/7-H, 11-H, 15-H/17-H), 7.76 (d, JAB ϭ 7.2 Hz, 2 H, 14-H/18-
H), 7.84Ϫ7.92 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H ppm. 13C NMR
(75 MHz, CDCl3): δ ϭ 106.9 (C2/C7), 112.8 (C-1), 119.0 (C-8),
126.4 (C-20/C-24), 126.7 (C-22), 126.8 (C-16), 127.4 (C-21/C-23),
127.5 (C-1a or C-7a), 127.6 (C-4/C-5), 127.9 (C-7a or C-1a), 128.6
(C-15/C-17), 128.7(0) (C-14/C-18), 128.7(5) (C-3/C-6), 130.0 (C-9), (E,E)-1-[1,5-Bis(p-tolyl)penta-1,4-dien-3-ylidene]-1H-cyclopropa[b]-
130.9 (C-10), 132.3 (C-11), 132.5 (C-12), 137.6 (C-19), 138.3 (C- naphthalene (16): Light petroleum/dichloromethane (2:1) elution
13), 138.8 (C-2a or C-6a), 138.9 (C-6a or C-2a) ppm. MS (70 eV): gave title compound 16. Yield 74 mg (55%). Red needles (light
m/z (%) ϭ 357 (27) [M ϩ 1]ϩ, 356 (100) [M]ϩ, 355 (69), 354 (21),
353 (30), 352 (26), 341 (29), 340 (31), 339 (54), 326 (21), 279 (79), δ ϭ 2.40 (s, 6 H, Me), 7.21 (d, JAB ϭ 8.5 Hz, 4 H, 13-H/15-H),
petroleum), m.p. 122.5Ϫ123.5 °C. 1H NMR (300 MHz, CDCl3):
3
3
3
278 (74), 277 (45), 276 (56), 265 (96), 253 (26), 252 (44), 169 (34). 7.23 (d, Jtrans ϭ 15.5 Hz, 2 H, 9-H), 7.34 (d, Jtrans ϭ 16.0 Hz, 2
IR (KBr): ν˜ ϭ 3028, 2926, 2855, 2372, 2345, 1870, 1831, 1774 (w), H, 10-H), 7.46Ϫ7.49 (m, 6 H, 4-H/5-H and 12-H/16-H), 7.51 (s, 2
1740, 1701, 1685, 1647, 1654 (s), 1636 (s), 1560, 1112, 983, 843 H, 2-H/7-H), 7.86Ϫ7.89 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H) ppm. 13
C
cmϪ1. UV/Vis (cyclohexane): λmax. (log ε) ϭ 328 (4.27), 458 (4.34),
486 nm (4.32). UV/Vis (acetonitrile): λmax.(log ε) ϭ 328 (4.25), 154
(4.37), 478 nm (4.33). Dipole moment (benzene): µ (22 °C) ϭ 1.38
NMR (75 MHz, CDCl3): δ ϭ 21.3 (Me), 106.6 (C-2/C-7), 111.8 (C-
1), 116.3 (C-8), 125.1 (C-9), 126.5 (C-12/C-16), 126.8 (C-4/C-5),
127.9 (C-1a/C-7a), 128.6 (C-3/C-6), 129.0 (C-10), 129.5 (C-13/C-
D. C28H20 (356.47): calcd. C 94.34, H 5.66; found C 94.22, H 5.78. 15), 135.0 (C-11), 137.5 (C-14), 139.0 (C-2a/C-6a) ppm. IR (KBr):
Eur. J. Org. Chem. 2004, 3707Ϫ3713
www.eurjoc.org  2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 3711

G. M. Dixon, B. Halton
FULL PAPER
ν˜ ϭ 2971, 2927, 2381, 2326, 2174, 1774 (w), 1719, 1654, 1647, 1636, (3.91), 462 (4.02), 496 nm (3.99). UV/Vis (acetonitrile) ): λmax. (log
1560, 1508, 1458, 1252, 1176, 1144, 1030 cmϪ1. UV/Vis (cyclohex- ε) ϭ 304 (4.01), 318 (3.98), 330 (3.96), 458 (4.06), 492 nm (4.05).
ane): λmax. (log ε) ϭ 308 (4.06), 326 (4.15), 340 (4.17), 464 (4.20),
Dipole moment (benzene): µ (22 °C) ϭ 1.38 D. C28H18F2 (392.45):
500 nm (4.21). UV/Vis (acetonitrile): λmax. (log ε) ϭ 308 (4.09), calcd. C 85.69, H 4.62; found C 85.75, H 4.78.
324 (4.17), 338 (4.19), 462 (4.22), 496 nm (4.24). Dipole moment
(benzene): µ (21 °C) ϭ 2.07 D. C30H24 (384.52): calcd. C 93.71, H
6.29; found C 93.65, H 6.35.
1-[2,5-Bis(p-tolylmethylidene)cyclopent-1-ylidene]-1H-cyclo-
propa[b]naphthalene (20): Light petroleum/dichloromethane (6:1)
elution gave title compound 20 as the most mobile fraction. Yield:
26 mg (18%). Yellow needles (light petroleum), m.p. 132.5Ϫ134.5
(E,E)-1-[1,5-Bis(p-methoxyphenyl)penta-1,4-dien-3-ylidene]-1H-
cyclopropa[b]naphthalene (17): Light petroleum/dichloromethane
1
°C. H NMR (300 MHz, CDCl3): δ ϭ 2.02 (s, 4 H, 17-H), 2.41 (s,
3
(4:1) elution gave title compound 17. Yield: 60 mg, (41%). Red-
6 H, Me), 7.26 (d, JAB ϭ 8.1 Hz, 4 H, 13-H/15-H), 7.35 (s, 2 H,
1
orange needles (light petroleum), m.p. 165.0Ϫ166.0 °C. H NMR 10-H), 7.45Ϫ7.49 (m, 6 H, 4-H/5-H and 12-H/16-H), 7.50 (s, 2 H,
(300 MHz, CDCl3): δ ϭ 3.86 (s, 6 H, OMe), 6.94 (d, JAB ϭ 8.7, 4
2-H/7-H), 7.85Ϫ7.90 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H) ppm. 13C
H, 13-H/15-H), 7.18 (d, Jtrans ϭ 16.2 Hz, 2 H, 9-H), 7.25 (d, NMR (75 MHz, CDCl3): δ ϭ 21.4 (Me), 32.2 (C-17), 107.6 (C-2/
3Jtrans ϭ 16.0 Hz, 2 H, 10-H), 7.45Ϫ7.48 (AAЈ of AAЈBBЈ, 2 H, 4-
C-7), 111.9 (C-1), 113.4 (C-8), 125.6 (C-9), 126.9 (C-4/C-5), 127.5
3
H/5-H), 7.48 (s, 2 H, 2-H/7-H), 7.55 (d, JAB ϭ 8.7 Hz, 4 H, 12-H/ (C-1a/C-7a), 127.7 (C-12/C-16), 129.0 (C-3/C-6), 129.4 (C-10),
16-H), 7.84Ϫ7.88 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H) ppm. 13C NMR 129.6 (C-13/C-15), 134.2 (C-11), 136.2 (C-14), 138.9 (C-2a/C-6a)
(75 MHz, CDCl3): δ ϭ 55.4 (OMe), 106.3 (C-2/C-7), 111.1 (C-1), ppm. HRMS (positive APCI): calcd. for C32H27 [M ϩ H]ϩ
114.2 (C-13/C-15), 116.7 (C-8), 124.1 (C-9), 126.7 (C-4/C-5), 127.8
411.2112; found 411.2116 (ϩ0.97 mmu). IR (KBr): ν˜ ϭ 3326, 3265,
(C-12/C-16), 128.0 (C-1a/C-7a), 128.6 (C-3/C-6), 128.7 (C-10), 2927, 2564, 2348, 2267, 1800, 1774 (w), 1564, 1467, 1326, 1308,
130.6 (C-11), 138.9 (C-2a/C-6a), 159.4 (C-14) ppm. IR (KBr): ν˜ ϭ 1081, 1003, 936, 772 cmϪ1. UV/Vis (cyclohexane): λmax. (log ε) ϭ
2924, 2843, 1774 (w), 1652, 1506, 1498, 1443, 1154, 1096, 756 cmϪ1
.
210 (4.01), 256 (3.99), 364 (3.85), 410 nm (4.12). UV/Vis (aceto-
nitrile): λmax. (log ε) ϭ 210 (4.01), 256 (3.98), 362 (3.83), 408 nm
(4.11). Dipole moment (benzene): µ (22 °C) ϭ 1.73 D.
UV/Vis (cyclohexane): (log ε) λmax. ϭ 310 (3.44), 336 (3.70), 348
(3.73), 468 (3.93), 504 nm (4.10).UV/Vis (acetonitrile): λmax. (log
ε) ϭ 310 (3.81), 336 (3.92), 348 (3.95), 464 (4.03), 500 nm (4.02).
Dipole moment (benzene): µ (21 °C) ϭ 3.38 D. C30H24O2 (416.52):
calcd. C 86.51, H 5.81; found C 86.48, H 5.92.
1-{2,5-Bis[(p-methoxyphenyl)methylidene]cyclopent-1-ylidene}-1H-
cyclopropa[b]naphthalene (21): Light petroleum/dichloromethane
(4:1) elution gave the title compound 21 as the most mobile frac-
tion. Yield: 40 mg (26%). Yellow needles (light petroleum), m.p.
156.5Ϫ158.5 °C. 1H NMR (300 MHz, CDCl3): δ ϭ 2.05 (s, 4 H,
(E,E)-1-[1,5-Bis(p-dimethylaminophenyl)penta-1,4-dien-3-ylidene]-
1H-cyclopropa[b]naphthalene (18): Light petroleum/dichlorometh-
ane (4:1) elution gave title compound 18. Yield: 126 mg (82%). Or-
3
17-H), 3.86 (s, 6 H, OMe), 6.91 (d, JAB ϭ 8.1 Hz, 4 H, 13-H/15-
ange microcrystals (light petroleum), m.p. 128.5Ϫ130.0 °C. 1H H), 7.16 (s, 2 H, 10-H), 7.45Ϫ7.49 (m, 4 H, 4-H/5-H and 2-H/7-
3
NMR (300 MHz, CDCl3): δ ϭ 3.03 (s, 12 H, NMe2), 6.77 (d, H), 7.50 (d, JAB ϭ 8.1 Hz, 4 H, 12-H/16-H), 7.84Ϫ7.88 (BBЈ of
3JAB ϭ 8.7 Hz, 4 H, 13-H/15-H), 7.21 (d, 3Jtrans ϭ 16.2 Hz, 2 H, 9-
AAЈBBЈ, 2 H, 3-H/6-H ppm. 13C NMR (75 MHz, CDCl3): δ ϭ
3
H), 7.31 (d, Jtrans ϭ 16.0 Hz, 2 H, 10-H), 7.44 (s, 2 H, 2-H/7-H), 32.3 (C-17), 55.3 (OMe), 107.4 (C-2/C-7), 111.6 (C-1), 114.0 (C-13/
7.45Ϫ7.48 (AAЈ of AAЈBBЈ, 2 H, 4-H/5-H), 7.52 (d, 3JAB ϭ 8.6 Hz,
4 H, 12-H/16-H), 7.81Ϫ7.87 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H ppm.
C-15), 115.1 (C-8), 125.6 (C-9), 126.7 (C-4/C-5), 127.6 (C-1a/C-
7a), 128.8 (C-3/C-6), 129.3 (C-10), 129.6 (C-12/C-16), 130.2 (C-
13C NMR (75 MHz, CDCl3): δ ϭ 40.1 (NMe2), 106.3 (C-2/C-7), 11), 138.7 (C-2a/C-6a), 159.2 (C-14) ppm. HRMS (positive APCI):
109.8 (C-1), 112.6 (C-13/C-15), 117.8 (C-8), 123.6 (C-9), 125.8 (C-
11), 126.6 (C-4/C-5), 127.6 (C-1a/C-7a), 127.7 (C-12/C-16), 128.6 mmu). IR (KBr): ν˜ ϭ 3025, 2927, 1845, 1774 (w), 1654, 1632, 1478,
(C-3/C-6), 128.7 (C-10), 138.7 (C-2a/C-6a) 149.7 (C-14) ppm. IR
1426, 1238, 1168, 1009, 993, 854 cmϪ1. UV/Vis (cyclohexane): λmax.
calcd. for C32H27O2 [M ϩ H]ϩ 443.2011; found 443.2008 (Ϫ0.68
(KBr): ν˜ ϭ 2922, 2856, 2170, 1632, 1604, 1519, 1504, 1384, 1187, (log ε) ϭ 228 (3.76), 246 (3.85), 326 (3.93), 420 nm (4.03). UV/Vis
1142, 1053, 875 cmϪ1. UV/Vis (cyclohexane): λmax. (log ε) ϭ 236 (acetonitrile): λmax. (log ε) ϭ 228 (3.76), 246 (3.87), 324 (3.92),
(3.84), 260 (3.57), 292 (3.44), 324 (3.35), 435 sh (4.04), 448 sh (4.11),
466 nm (4.19), 485 sh (3.91).UV/Vis (acetonitrile): λmax. (log ε) ϭ
236 (3.81), 260 (3.66), 290 (3.59), 322 (3.46), 462 nm (4.10). Dipole
moment (benzene): µ (21 °C) ϭ 4.23 D. C32H30N2 (442.61): calcd.
C 86.84, H 6.83, N 6.33; found C 86.84, H 6.74, N 6.42.
416 nm (4.00). Dipole moment (benzene): µ (22 °C) ϭ 2.91 D.
1-{2,5-Bis[(p-dimethylaminophenyl)methylidene]cyclopent-1-
ylidene}-1H-cyclopropa[b]naphthalene (22): Light petroleum/di-
chloromethane (4:1) elution gave the title compound 22 as the most
mobile fraction. Yield: 69 mg (42%). Orange needles (light petro-
(E,E)-1-[1,5-Bis(p-fluorophenyl)penta-1,4-dien-3-ylidene]-1H-cyclo-
propa[b]naphthalene (19): Light petroleum/dichloromethane (2:1) 2.05 (s, 4 H, 17-H), 3.01 (s, 12 H, NMe2), 6.80 (d, JAB ϭ 8.1 Hz,
leum), m.p. 136.5Ϫ137.5 °C. 1H NMR (300 MHz, CDCl3): δ ϭ
3
elution gave title compound 19. Yield: 93 mg (68%). Orange-red
needles (light petroleum), m.p. 147.5Ϫ149.0 °C. 1H NMR
(300 MHz, CDCl3): δ ϭ 7.09 (t, J ϭ 8.7 Hz, 4 H, 13-H/15-H), 7.16
(d, 3Jtrans ϭ 16.2 Hz, 2 H, 9-H), 7.26 (d, 3Jtrans ϭ 16.2 Hz, 2 H, 10-
4 H, 13-H/15-H), 7.22 (s, 2 H, 10-H), 7.42 (s, 2 H, 2-H/7-H),
7.46Ϫ7.57 (m, 6 H, 4-H/5-H and 12-H/16-H), 7.82Ϫ7.86 (BBЈ of
AAЈBBЈ, 2 H, 3-H/6-H) ppm. 13C NMR (75 MHz, CDCl3): δ ϭ
32.6 (C-17), 40.5 (NMe2), 106.4 (C-2/C-7), 110.1 (C-1), 112.5 (C-
H), 7.48Ϫ7.51 (AAЈ of AAЈBBЈ, 2 H, 4-H/5-H), 7.53Ϫ7.58 (m, 6 13/C-15), 116.5 (C-8), 123.3 (C-9), 126.5 (C-4/C-5), 127.5 (C-1a/C-
H, 2-H/7-H and 12-H/16-H), 7.87Ϫ7.90 (BBЈ of AAЈBBЈ, 2 H, 3- 7a), 128.5 (C-10), 128.6 (C-3/C-6), 128.8 (C-11), 129.6 (C-12/C-16),
H/6-H) ppm. 13C NMR (75 MHz, CDCl3): δ ϭ 107.0 (C-2/C-7), 138.7 (C-2a/C-6a), 149.8 (C-14) ppm. HRMS (positive APCI):
112.5 (C-1), 115.5 (C-8), 115.7 (d, 2JC,F ϭ 22 Hz, C-13/C-15), 125.7
calcd. for C34H33N2 [M ϩ H]ϩ 469.2643; found 469.2649 (ϩ1.28
6
(d, JC,F ϭ 2.5 Hz, C-9), 127.0 (C-4/C-5), 127.6 (C-1a/C-7a), 127.7 mmu). IR (KBr): ν˜ ϭ 3204, 3122, 2927, 2900, 2774, 1896, 1774 (w).
3
(C-10), 128.0 (d, JC,F ϭ 8 Hz, C-12/C-16), 128.7 (C-3/C-6), 133.8
1652, 1603, 1548, 1449, 1423, 1208, 1193, 1134, 1008, 1000, 923,
4
1
(d, JC,F ϭ 3 Hz, C-11), 139.0 (C-2a/C-6a), 162.3 (d, JC,F
ϭ
855 cmϪ1. UV/Vis (cyclohexane): λmax. (log ε) ϭ 246 (4.00), 256
248 Hz, C-14) ppm. IR (KBr): ν˜ ϭ 2923, 2833, 1773 (w), 1636, (3.93), 288 (3.82), 422 nm (4.18). UV/Vis (acetonitrile): λmax. (log
1505, 1423, 1384, 1220, 1144, 1094, 952, 816, 734, 610 cmϪ1. UV/
Vis (cyclohexane): ): λmax. (log ε) ϭ 306 (3.96), 320 (3.94), 332
ε) ϭ 246 (3.84), 254 (3.91), 286 (3.77), 418 nm (4.10). Dipole
moment (benzene): µ (22 °C) ϭ 3.51 D.
3712
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 3707Ϫ3713

Cross-Conjugated π-Extended Alkylidenecycloproparenes
FULL PAPER
A. Hinchliffe, H. J. S. Machado, Int. J. Mol. Sci. 2000, 1,
39Ϫ48.
A. P. Scott, I. Agranat, P. U. Biedermann, N. V. Riggs, L. Ra-
dom, J. Org. Chem. 1997, 62, 2026Ϫ2038.
J. Daub, L. W. Jenneskens, Chimia 1987, 41, 52Ϫ59.
M. Neuenschwander, Pure Appl. Chem. 1986, 58, 55Ϫ66.
M. Hanack, K. Ritter, I. Stein, W. Hiller, Tetrahedron Lett.
1986, 27, 3357Ϫ3360.
B. Halton, R. Boese, G. M. Dixon, Tetrahedron Lett. 2004,
45, 2167Ϫ2170.
K. Ogawa, T. Sano, S. Yoshimura, K. Toriumi, J. Am. Chem.
Soc. 1992, 114, 1041Ϫ1051.
M. Olomucki, J. Y. Le Gall, Bull. Soc. Chim. Fr. 1976,
[16]
[17]
1-[Bis(p-fluorophenyl)methylidene]-1H-cyclopropa[b]naphthalene:
Light petroleum elution gave the title compound. Yield: 38 mg
(32%). Bright yellow needles (light petroleum), m.p. 133.0Ϫ135.0
°C. 1H NMR (300 MHz, CDCl3): δ ϭ 7.13 (t, JAB
ഠ ഠ
3JH,F
[18]
[19]
[20]
8.8 Hz, 4 H, 11-H/13-H), 7.46Ϫ7.50 (AAЈ of AAЈBBЈ, 2 H, 4-H/5-
3
4
H), 7.52 (s, 2 H, 2-H/7-H), 7.68 (dd, JAB ϭ 9.0, JH,F ϭ 5.4 Hz, 4
H, 10-H/14-H), 7.85Ϫ7.89 (BBЈ of AAЈBBЈ, 2 H, 3-H/6-H) ppm.
13C NMR (75 MHz, CDCl3): δ ϭ 107.2 (C-2/C-7), 111.6 (C-1),
[21]
[22]
[23]
[24]
[25]
[26]
2
115.5 (d, JC,F ϭ 22 Hz, C-11/C-13), 117.7 (C-8), 126.8 (C-4/C-5),
3
128.8 (C-3/C-6), 129.6 (d, JC,F ϭ 8 Hz, C-10/C-14), 135.4 (d,
1
4JC,F ϭ 4 Hz, C-9), 138.7 (C-2a/C-6a), 162.1 (d, JC,F ϭ 247 Hz,
C-12) ppm. MS (70 eV): m/z (%) ϭ 341 (26) [M ϩ 1]ϩ, 340 (100)
[M]ϩ, 339 (37) [M Ϫ H]ϩ, 338 (59), 336 (15), 318 (13). IR (KBr):
ν˜ ϭ 3037, 2929, 2853, 1769 (w), 1648, 1601, 1506 (s), 1429, 1230,
1136, 1101, 1007, 839, 752 cmϪ1. UV/Vis (cyclohexane): λmax. (log
ε) ϭ 228 (4.35), 248 (4.23), 406 (4.25), 430 nm (4.27). UV/Vis
(acetonitrile): λmax. (log ε) ϭ 230 (4.33), 286 (3.87), 408 (4.21),
434 nm (4.25). Dipole moment (benzene): µ (22 °C) ϭ 0.87 D.
C24H14F2 (340.37): calcd. C 84.69, N 4.15; found C 84.79, N 4.12.
1467Ϫ1468.
H. Frey, G. Behmann, G. Kaupp, Chem. Ber. 1987, 120,
387Ϫ393.
N. Marcotte, S. Fery-Forgues, J. Photochem. Photobiol. A 2000,
130, 133Ϫ138.
N. Marcotte, S. Fery-Forgues, S. Lavabre, S. Marguet, V. G.
Pivovarenko, J. Phys. Chem. A 1999, 103, 3163Ϫ3170; N. Mar-
cotte, S. Fery-Forgues, J. Chem. Soc., Perkin Trans. 2 2000,
1711Ϫ1716.
See e.g.: T. Hoshi, T. Kawashima, J. Okubo, M. Yamamoto,
H. Inoue, J. Chem. Soc., Perkin Trans. 2 1986, 1147Ϫ1150; H.
Tanaka, K. Yamada, H. Kawazura, J. Chem. Soc., Perkin
Trans. 2 1978, 231Ϫ235, and refs cited.
G. Venkateshwarlu, B. Subrahmanyam, Proc. Indian Acad. Sci.
1987, 99, 419Ϫ424; G. Venkateshwarlu, B. Subrahmanyam,
Proc. Indian Acad. Sci. 1990, 102, 45Ϫ50.
J. E. Dubois, W. V. Wright, Tetrahedron Lett. 1967, 3101Ϫ3106;
B. M. Webster, Prog. Stereochem. 1958, 2, 99.
[27]
Acknowledgments
Financial support for this work from Victoria University is grate-
fully acknowledged.
[28]
[29]
[1]
B. Halton, C. J. Randall, G. J. Gainsford, P. J. Stang, J. Am.
Chem. Soc. 1986, 108, 5949Ϫ5956.
B. Halton, A. J. Kay, Z. Zhi-mei, R. Boese, T. Haumann, J.
[2]
[30]
[31]
G. Wypych, Handbook of Solvents, Chem. Tec., Toronto, 2001.
Q. Lu, PhD thesis, Victoria University of Wellington, New
Zealand, 1989.
Chem. Soc., Perkin Trans. 1 1996, 1445Ϫ1452.
[3]
B. Halton, R. Boese, G. M. Dixon, Eur. J. Org. Chem. 2003,
4507Ϫ4512.
B. Halton, P. J. Stang, Synlett 1997, 145Ϫ158.
B. Halton, C. J. Randall, P. J. Stang, J. Am. Chem. Soc. 1984,
106, 6108Ϫ6110.
[32]
[4]
The ratio of dipole moments of the s-cis,s-cis and s-cis,s-trans
rotamers of 16؊18 should approximate to the 0.79 value for
23. Assuming the experimentally determined dipole moments
of the ‘‘locked’ cyclopentanones 20؊23 to represent the s-cis,s-
cis rotamers of 16؊18, the ratio of s-cis,s-cis to s-cis,s-trans
rotamers (benzene solution) of each of 16؊18 is approximated
as shown for 16 in Equation (2), where y ϭ proportion of s-
cis,s-cis rotamer.
[5]
[6]
B. Halton, S. J. Buckland, Q. Lu, Q. Mei, P. J. Stang, J. Org.
Chem. 1988, 53, 2418Ϫ2422.
B. Halton, Q. Lu, P. J. Stang, J. Chem. Soc., Chem. Commun.
[7]
1988, 879Ϫ880.
Y. Apeloig, R. Boese, D. Bläser, B. Halton, A. H. Maulitz, J.
[8]
[y ϫ µ-20] ϩ [(1 Ϫ y) ϫ µ-s-cis,s-trans-16] ϭ µ-16recorded (2)
For 16: [y ϫ 1.73] ϩ [(1 Ϫ y) ϫ 1.73/0.79] ϭ 2.06; with y ϭ
0.283 and s-cis,s-cis/s-cis,s-trans ϭ 28:72.
Am. Chem. Soc. 1998, 120, 10147Ϫ10153.
[9]
B. Halton, Q. Lu, W. H. Melhuish, J. Photochem. Photobiol.,
A: Chem. 1990, 52, 205Ϫ208.
B. Halton, Chem. Rev. 2003, 103, 1327Ϫ1370.
B. Halton, C. S. Jones, D. Margetic, Tetrahedron 2001, 57,
3529Ϫ3536.
[33]
[10]
D. D. Perrin, W. L. F. Aramarego, D. R. Perrin, Purification of
Laboratory Chemicals, 2nd ed., Pergamon, London, 1980.
E. A. Guggenheim, Trans. Faraday Soc. 1949, 45, 714Ϫ720.
J. W. Smith, Trans. Faraday Soc. 1950, 394Ϫ399.
C. R. Conrad, M. A. Dolliver, Org. Synth. 1932, 12, 22Ϫ24.
S. Watanasin, W. S. Murphy, Synthesis 1980, 647Ϫ650.
J. M. Eisenhart, A. B. Ellis, J. Org. Chem. 1985, 50, 4108Ϫ4113.
S. Spange, A. Seifert, H. Muller, S. Hesse, C. Jager, Angew.
Chem. Int. Ed. 2002, 41, 1729Ϫ1732; P. J. Mitchell, L. Phillips,
S. J. Roberts, V. Wray, Org. Magn. Reson. 1974, 6, 126Ϫ127.
Received May 20, 2004
[11]
[34]
[35]
[36]
[37]
[38]
[39]
[12]
B. Halton, C. S. Jones, P. T. Northcote, R. Boese, Aust. J.
Chem. 1999, 52, 285Ϫ290.
[13]
B. Halton, C. S. Jones, Eur. J. Org. Chem. 2004, 138Ϫ146.
[14]
G. M. Dixon, PhD thesis, Victoria University of Wellington,
New Zealand, 2002.
B. Halton, M. J. Cooney, T. W. Davey, G. S. Forman, Q. Lu,
R. Boese, D. Bläser, A. H. Maulitz, J. Chem. Soc., Perkin Trans.
1 1995, 2819Ϫ2827.
[15]
Eur. J. Org. Chem. 2004, 3707Ϫ3713
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3713