New syntheses of di-π-substituted heptalenes

Article abstract of DOI:10.1002/(SICI)1522-2675(19991215)82:12<2260::AID-HLCA2260>3.0.CO;2-Z

To study the effect of double-bond shifts (DBS) in different type of heptalenes linked to extended π-systems, several di-π-substituted heptalenes were synthesized. 6-[(E)-Styryl]heptalene-dicarboxylate 4 was smoothly converted to 1-(chloromethyl)heptalene

Full text of DOI:10.1002/(SICI)1522-2675(19991215)82:12<2260::AID-HLCA2260>3.0.CO;2-Z

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Helvetica Chimica Acta ± Vol. 82 (1999)
New Syntheses of Di-p-Substituted Heptalenes
by Jianfeng Song and Hans-Jürgen Hansen*
Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich
To study the effect of double-bond shifts (DBS) in different type of heptalenes linked to extended p-
systems, several di-p-substituted heptalenes were synthesized. 6-[(E)-Styryl]heptalene-dicarboxylate 4 was
smoothly converted to 1-(chloromethyl)heptalene-dicarboxylate 5 by treatment with t-BuOK and C2Cl6 in THF
at 788. The one-pot reaction of 5 and P(OEt)3 in the presence of NaI, followed by Wittig-Horner reaction,
afforded the 1,6-di-p-substituted heptalene 6. The reaction of 6-[(1E,3E)-4-phenylbuta-1,3-dienyl]heptalenes 7
or 15 with t-BuOK and benzaldehyde in THF led to the formation of the 1,6-di-p-substituted heptalenes 13 or
16, together with transesterification products 14 or 17. The transformation of the MeOCO group at C(4) of 6-
[(E)-styryl]heptalene-dicarboxylate 4 to a phenylbuta-1,3-dienyl substituent afforded the 4,6-di-p-substituted
heptalene 21a, which is in thermal equilibrium with its DBS isomer 21b in solution. Oxidation of heptalene 22
with SeO2 in dioxane gave carbaldehyde 23, which was then subjected to a Wittig reaction to give the 6,9-di-p-
substituted heptalene-dicarboxylate 24.
1. Introduction. ± We have recently shown that two p-substituents at appropriate
positions of the heptalene skeleton lead to an enhanced electronic interaction between
the two p-substituents via buta-1,3-diene subunits of the heptalene p-skeleton (cf.
heptalene 1) [1] [2]. This enhanced p-interaction of the substituents with the heptalene
core can be destroyed on thermal or photochemical double-bond shift (DBS) to the
corresponding not fully conjugated heptalene isomer 2. These interconversions
correspond to a negative thermo- or photochromism, which is positive for the reverse
reaction from 2 to 1 (Scheme 1).
Scheme 1
To investigate this enhanced p-interaction of substituents in different types of di-p-
substituted heptalenes, we developed the synthesis of such heptalenes.
2. Results and Discussion. ± 2.1. 1,6-Di-p-Substituted Heptalenes. 2.1.1. With an i-Pr
Group at C(9). The reaction of easily available 4-styrylazulenes 3a or 3b [3] with ADM
in the presence of catalytic amounts of [RuH2(PPh3)4] in MeCN at 1108 represents the
shortest pathway to the 6-styrylheptalene-dicarboxylates 4a or 4b in reasonable yields

Helvetica Chimica Acta ± Vol. 82 (1999)
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[4] (Scheme 2). The construction of a second p-substituent from Me C(1) of 4 was
achieved according to the protocol that was established earlier in our group [2]. The
reaction of 4a or 4b with t-BuOK in THF at
788 in the presence of C2Cl6 as
electrophilic chlorinating agent gave, in excellent yield, the 1-(chloromethyl)heptalene-
dicarboxylates 5a or 5b. The one-pot reaction of 5a or 5b, and P(OEt)3 in the presence
of NaI at 1308 for 4 h, followed by Wittig-Horner reaction, afforded 1,6-di-p-substituted
heptalene-dicarboxylates 6a or 6b in good yield. Unfortunately, compounds 6a or 6b
showed no detectable DBS to the other isomer on heating or on irradiation at room
temperature. The UV/VIS spectra of 6a or 6b do not show strong absorption at long
wavelengths (Fig. 1), since the two p-substituents cannot interact with each other via
the central s-trans-buta-1,3-diene subunit of 6a or 6b.
Scheme 2
2.1.2. With t-Bu or Me Groups at C(8). The electrophilic chlorination of heptalene 7
was performed as described for 4. However, 1-(chloromethyl)heptalene-dicarboxylate
8 was formed in only 25% yield (Scheme 3), and it was impossible to separate 8 from
non-reacted 7 (recovered in 35% yield) by column chromatography. The 1H-NMR data
of the mixture 7/8 showed an AB system at 4.25 and 3.95 ppm (JAB ˆ 13.7 Hz), which is
characteristic for ClCH2 C(1) of heptalene-4,5-dicarboxylates. So, it was easy to
determine the amount of 7 and 8 from the mixture. Heating the mixture 7/8 with
P(OEt)3 at 1308 for 4 h did not lead to the corresponding phosphonate. Therefore, we
had to search for another way to introduce the second p-substituent at C(1). Basu et al.
[5] (see also [6]) reported that the reaction of a,b-unsaturated esters with aldehydes in
the presence of t-BuOK in t-BuOH lead to the formation of a second s-trans-conjugated
CˆC bond in g-position. Dehmlow and Shamount [7] found that, in similar reactions,

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Helvetica Chimica Acta ± Vol. 82 (1999)
Fig. 1. UV/VIS Spectra (hexane) of heptalene 6a and 6b
Scheme 3
a) Starting heptalene 7 was still present in an amount of 35%.
K2CO3 can act as a base, when the reactions are performed in toluene in the presence of
phase-transfer catalysts.
To examine whether these procedures are also applicable to 1-methylheptalene-4,5-
dicarboxylates, we chose our standard heptalene 9 as model compound. Treatment of 9
with PhCHO in the presence of t-BuOK in t-BuOH at 658 for 4 h (Scheme 4) gave
indeed the 1-styrylheptalene-dicarboxylate 10a in 23% yield. Replacing t-BuOH with
THF and lowering the temperature to 0 ! 258 augmented the yield of 10a to 44%. On
the other hand, under the same conditions, 4-nitrostyrylheptalene-dicarboxylate 10b
could be obtained in only 8% yield. The application of the same procedure to dimethyl
1,6,8,10-tetramethylheptalene-4,5-dicarboxylate (11) provided 1-styrylheptalene-dicar-
boxylate 12a and its derivative 12b in moderate yields. These results demonstrate that,
in principle, a simple method is at our disposal for the introduction of styryl substituents
at C(1) of 1-methylheptalene-4,5-dicarboxylates in just one step with similar yields as
compared to our earlier, at minimum three-step, procedure [2].
As expected, reaction of heptalene 7 with PhCHO and t-BuOK in THFafforded the
1,6-di-p-substituted heptalene 13 in 33% yield and, in addition, the transesterified
heptalene-dicarboxylate 14 in 25% yield (Scheme 5). The formation of 14 is not
surprising, since the Cannizzaro reaction of PhCHO takes place under basic condition
to give PhCH2O , which attacks MeOCO C(4) of 13 to form the transesterification
product 14. The separation of 13 and 14 could easily be realized by column

Helvetica Chimica Acta ± Vol. 82 (1999)
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Scheme 4
chromatography on silica gel, since 13 (Rf(hexane/Et2O 1:1) 0.30) and 14 (Rf(hexane/
1
Et2O 1:1) 0.41) showed sufficiently different Rf in TLC. The H-NMR spectrum
(CDCl3) of 13 resembled very much that of 14 with the difference that 14 exhibited
PhCH2OOC C(4) as a singlet at 5.19 and the singlet of MeOCO C(5) at 3.35 ppm,
while 13 showed two singlets of MeOCO C(4) and MeOCO C(5) at 3.75 and
3.55 ppm. Under the same conditions, the reaction of the trimethylheptalene-
dicarboxylate 15 with PhCHO led to the formation of the 1,6-di-p-substituted
derivatives 16 (19%) and 17 (25%). As expected, there is nearly no difference in the
UV/VIS spectra of 13, 14, 16, and 17 (Fig. 2). All four heptalenes exhibited Band I as a
weak shoulder at ca. 420 nm, followed by the much more intense shoulder of Band II at
ca. 350 nm, which is just recognizable at the long-wavelength flank of Band III. The
latter one, appearing at 324 nm, represents the dominating absorption band in the
spectrum. However, as it was already recognizable in the UV/VIS spectra of the i-Pr-
Scheme 5

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Fig. 2. UV/VIS Spectra (hexane) of 13, 14, 16, and 17
substituted heptalenes 6a and 6b, the intensity of Band II of 13, 14, 16, and 17 is strongly
enhanced as compared with corresponding heptalenes mono-p-substituted at C(1) or
C(6) (cf. Fig. 8, b, as well as Fig. 10, c and e in [8]). Moreover, a comparison of the
position of Band II of 6a and 6b with that of 13, 14, 16, and 17 discloses a hypsochromic
shift by ca. 25 nm for the latter four heptalenes with four substituents in the peri-
positions. This general finding is in agreement with smaller torsion angles of 6a and 6b,
which carry only three peri-substituents. Neither irradiation nor heating of 13, 14, 16, or
17 led to the formation of the corresponding DBS isomers in detectable amounts
(HPLC). This means that, at temperatures above 258, the thermal equilibrium of all
these 1,6-di-p-substituted heptalenes and their DBS isomers are to more than 99% on
the side of the off-state, where the two p-substituents are not directly interacting with
each other via the central s-trans-butadiene subunit of the heptalene core.
2.2. 4,6-Di-p-Substituted Heptalenes. The transformation of the MeOCO group at
C(4) of heptalene 4a into an extented p-substituent was achieved according to
established methods in our group. Selective saponification of MeOCO C(4) of
heptalene 4a gave, in nearly quantitative yield, the mono-acid 18, which was cyclized to
pseudo-ester 19 under Stadler conditions. The controlled reduction of 19 with 1 equiv.
of DIBAH in toluene at
808 for 15 min gave the expected carbaldehyde 20. The
subsequent Wittig reaction of 20 in a two-phase system (CH2Cl2/2n NaOH) proceeded

Helvetica Chimica Acta ± Vol. 82 (1999)
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smoothly and gave the 4,6-di-p-substituted heptalene 21a, which is in thermal
equilibrium with 10% of its DBS isomer 21b at room temperature (Scheme 6). The
torsion angle of the involved s-trans-butadiene subunit is ca. 1188, which should lead to
a reduction of conjugation by ca. 60% [8]. Therefore, although the two p-substituents
in 21b are linked to each other through the s-trans-butadiene subunit of the heptalene
core, the two p-substituents still interact more or less independently with the heptalene
p-system. Indeed, the UV/VIS spectra of 21a and 21b resemble each other (Fig. 3). In
other words, the thermal equilibrium of 4,6-di-p-substituted 21a/21b is not very
effective with respect to changes in the chromism.
Scheme 6
2.3. 6,9-Di-p-Substituted Heptalene. Heptalenes such as 22 carry Me substituents
always in allylic positions, so it should be possible to functionalize such groups.
However, former attempts [2] to functionalize dimethyl 9-isopropyl-1,6-dimethylhep-
talene-4,5-dicarboxylate, either by bromination with NBS or oxidation with SeO2 in
toluene, led to the formation of the desired products in only very poor yields. Therefore,
we were not surprised when we found that heating of heptalene 22 with SeO2 in toluene
for 4 h led to only trace amounts of the carbaldehyde 23 (< 5%), but > 70% of
heptalene 22 could be recovered. The oxidation with SeO2 worked much better in
dioxane as solvent. Carbaldehyde 23 was obtained with good yield under this condition.
The subsequent Wittig reaction in the two-phase system smoothly converted

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Fig. 3. UV/VIS Spectra (hexane/CH2Cl2) of heptalenes 21a and 21b
carbaldehyde 23 to 6,9-di-p-substituted heptalene-dicarboxylate 24 (Scheme 7). The
1H-NMR spectrum of 23 displayed the signals of the side chain at C(6) as typical s-
trans-buta-1,3-dienyl substituent with H C(3') at 6.82 ppm (dd, J(3',4') ˆ 15.5,
J(2',3') ˆ 10.7) and H C(2') at 6.63 ppm (dd, J(1',2') ˆ 15.5, J(2',3') ˆ 10.7). Unfortu-
nately, the signals of the butadienyl side chain at C(6) of di-p-substituted heptalene 24
were similar to that of heptalene 22, i.e., the signals of H C(1') and H C(2') were too
close together at 6.48 ppm to clearly recognize the coupling constants. The conforma-
tions of the side chains of 24 were, therefore, confirmed by an X-ray crystal-structure
analysis (Fig. 4), which revealed that both butadienyl groups were indeed s-trans-
configured, and they were in s-trans-configurations with respect to the relevant CˆC
bonds of the heptalene core. There is a long-wavelength absorption in the UV/VIS
spectra of 24, but neither photochemical nor thermal treatment of 24 led to the
formation of its DBS isomer. Moreover, there is an evident difference in the UV/VIS
spectra of the on-state situation of 24 (Fig. 5) and that of methyl 1,4-bis[(1E,3E)-4-
Scheme 7

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2267
phenylbuta-1,3-dienyl]-9-isopropyl-6-methylheptalene-5-carboxylate (see Fig. 4 in
[1]), which is comparable with 24, but carries the MeOCO group at the same ring as
the butadienyl moieties. The relative intensity of Band I in relation to the intensity of
Band III is much larger in the latter heptalene as compared with 24.
Fig. 4. Stereoscopic view of the X-ray crystal structure of heptalene 24
Fig. 5. UV/VIS Spectra of heptalene 24

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Helvetica Chimica Acta ± Vol. 82 (1999)
3. Concluding remarks. ± Our results confirm that enhanced conjugation via s-cis-
buta-1,3-diene subunits in the heptalene core is much more effective than that via
corresponding s-trans-buta-1,3-diene subunits. The DBS processes, which turn on or off
enhanced conjugation via the s-cis-buta-1,3-diene subunits of heptalenes, are accom-
panied by ꢀon- or off-switchingꢁ of observable properties, such as chemical shifts and
coupling constants, or UV/VIS absorption bands. Thus, a further step has been achieved
towards new systems for molecular switches or data storage systems.
We thank Dr. A. Linden for the X-ray crystal diffraction analyses, Prof. M. Hesse and his co-workers for
mass spectra, our NMR department for NMR support and 2 D-NMR measurements, and our analytical
laboratory for elemental analyses. The financial support of this work by the Swiss National Science Foundation is
gratefully acknowledged.
Experimental Part
General. See [3]. Azulene 3a and 3b were available from [3]. Heptalenes 4a and 4b were synthesized
according to [4]. And heptalenes 7, 15, and 22 were available from our previous work [9].
1. Syntheses of Heptalenes. ± 1.1 Dimethyl 1-(Chloromethyl)-9-isopropyl-6-[(E)-2-phenylethenyl]hepta-
lene-4,5-dicarboxylate (5a). At 788, to the stirred soln. of heptalene 4a (1.286 g, 3.0 mmol) and C2Cl6 (3.55 g,
15 mmol) in THF (30 ml) was added the soln. of t-BuOK (1.35 g, 12 mmol) in THF (15 ml) during 40 min.
Stirring was continued at 788 for 2 h before H2O was added to quench the reaction. Extraction with Et2O,
followed by CC (silica gel; hexane/Et2O 3 : 1), provided 1.26 g (90.7%) of 5a. Yellow crystals. M.p. 116.4 ± 116.98
(hexane). Rf (hexane/Et2O 1 : 1): 0.33. UV/VIS (hexane): lmax 350 (sh, 4.07), 306 (4.38), 257 (4.40); lmin 279
(4.24), 226 (4.29). IR (KBr): 2959m, 1720s, 1434m, 1255s, 1229m, 1195m, 1162w, 1085m, 1051m, 964w, 751m,
694w. 1H-NMR (300 MHz, CDCl3): 7.64 (d, J(2,3) ˆ 6.3, H C(3)); 7.33 (m, 2 arom. H); 7.26 (m, 2 arom. H);
7.20 (m, 1 arom. H); 6.85 (d, J ˆ 16.2, CHˆCH C(6)); 6.65 (d, J(2,3) ˆ 6.3, H C(2)); 6.55 (d, J ˆ 16.2,
CHˆCH C(6)); 6.47 (d, J(7,8) ˆ 6.9, H C(7)); 6.43 (d, J(7,8) ˆ 6.9, H C(8)); 6.02 (s, H C(10)); 4.19, 4.12
(AB, JAB ˆ 13.2, CH2Cl); 3.73, 3.49 (2s, MeOCO); 2.55 (sept., J ˆ 6.8, Me2CH); 1.12, 1.09 (2d, J ˆ 6.9, Me2CH).
.
‡
‡
‡
EI-MS: 464/462 (6/18, M ), 427 (18, [M Cl] ), 405/403 (8/24, [M MeOCO] ).
1.2. Dimethyl 9-Isopropyl-1-[(1E,3E)-4-phenylbuta-1,3-dienyl]-6-[(E)-2-phenylethenyl]heptalene-4,5-di-
carboxylate (6a). Compound 5a (325 mg, 0.7 mmol) and NaI (105 mg, 0.7 mmol) in P(OEt)3 (8 ml) were
heated at 1308 for 2 h. After filtration, the excess P(OEt)3 was removed under reduced pressure to leave an
orange oil, which was then dissolved in THF (5 ml). To this soln. at
788 was added 2n THF solution of
NaN(SiMe3)2 (0.4 ml, 0.8 mmol), and, after 20 min, cinnamaldehyde (0.53 ml, 4.2 mmol) was added. The
mixture was warmed within 4 h to 258, and H2O was added to quench the reaction. Extraction with Et2O and
normal workup resulted in a yellow residue, which was further purified by CC (silica gel; hexane/Et2O 9:1) to
give 6a (190 mg, 50.1%). Orange crystals. M.p. 210.4 ± 211.38 (Et2O/hexane). Rf (hexane/Et2O 1 : 1) 0.32. UV/
VIS (hexane; see also Fig. 1): lmax 420 (sh, 4.05), 380 (sh, 4.50), 328 (4.57), 299 (4.52); lmin 303 (4.52), 251
(4.33). IR (KBr): 2957w, 1718s, 1596w, 1534w, 1508w, 1434m, 1260s, 1202w, 1086w, 1051w, 987w, 749m, 691w.
1
1H-NMR (600 MHz, CDCl3) ): 7.74 (d, J(2,3) ˆ 6.8, H C(3)); 7.52 (m, 4 arom. H); 7.26 (m, 4 arom. H); 7.17
(m, 2 arom. H); 6.87 (d, J ˆ 16.0, CHˆCH C(6)); 6.77 (dd, J(3',4') ˆ 15.5, J(2',3') ˆ 10.7, H C(3')); 6.54 (d,
J(1',2') ˆ 15.0,
H
C(1')); 6.53 (m,
H
C(7,8)); 6.53 (d, J(3',4') ˆ 15.5,
H
C(4')); 6.50 (d, J ˆ 16.0,
CHˆCH C(6)); 6.47 (d, J(2,3) ˆ 6.9, H C(2)); 6.46 (dd, J(1',2') ˆ 15.5, J(2',3') ˆ 10.7, H C(2')); 5.98 (s,
H
C(10)); 3.74, 3.50 (2s, MeOCO); 2.57 (sept., J ˆ 6.8, Me2CH); 1.13, 1.11 (2d, J ˆ 6.8, Me2CH). 13C-NMR
(75 MHz, CDCl3): 167.58, 167.10 (2s, MeOCO); 150.09 (s); 142.91 (s); 139.74 (d); 137.92 (s); 137.12 (s); 136.84
(s); 135.52 (d); 133.57 (d); 132.98 (d); 131.75 (s); 130.61 (s); 130.06 (d); 128.56 (d, 4 arom. C); 128.38 (d, 2 arom.
C); 128.32 (d); 128.19 (d); 127.97 (d); 127.91 (d); 127.34 (d); 127.24 (s); 126.54 (s); 126.44 (d, 4 arom. C); 125.77
(d); 52.08, 51.95 (2q, MeOCO); 35.85 (d, Me2CH); 23.06, 22.20 (2q, Me2CH). CI-MS: 544 (18), 543 (47, [M ‡
‡
‡
1] ), 511 (100, [(M ‡ 1) MeOH] ). Anal. cal. for C37H34O4 (542.68): C 81.89, H 6.31; found: C 81.52, H 6.47.
1.3. Dimethyl 1-(Chloromethyl)-9-isopropyl-6-[(E)-2-(4-methoxyphenyl)ethenyl]heptalene-4,5-dicarboxy-
late (5b). The chlorination of 4b (0.803 g, 1.75 mmol) with C2Cl6 (2.07 g, 8.75 mmol) in the presence of t-BuOK
(0.786 g, 7.0 mmol) in THF was achieved as described for 4a to give 5b (776 mg, 90%). Yellow crystals. M.p.
1
)
The C-atoms of the butadienyl side chain are indicated with primed numbers.

Helvetica Chimica Acta ± Vol. 82 (1999)
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147.7 ± 148.98 (hexane). Rf (hexane/Et2O 1 :1): 0.33. UV/VIS (hexane): lmax 318 (4.35), 256 (4.35); lmin 284
(4.22), 231 (4.29). IR (KBr): 2958w, 1718s, 1606w, 1572w, 1511m, 1435w, 1254s, 1174m, 1088w, 1036w, 965w,
831w, 794w. 1H-NMR (300 MHz, CDCl3): 7.64 (d, J(2,3) ˆ 6.2, H C(3)); 7.28 (d-like, J ˆ 8.8, 2 arom. H); 6.80
(d-like, J ˆ 8.8, 2 arom. H); 6.73 (d, J ˆ 16.1, CHˆCH C(6)); 6.65 (d, J(2,3) ˆ 6.2, H C(2)); 6.49 (d, J ˆ 16.1,
CHˆCH C(6)); 6.45 (d, J(7,8) ˆ 6.8, H C(7)); 6.38 (d, J(7,8) ˆ 6.8, H C(8)); 6.01 (s, H C(10)); 4.20, 4.11
(AB, JAB ˆ 13.0, CH2Cl); 3.79, 3.74 (2s, MeOCO); 3.49 (s, MeOC6H4); 2.54 (sept., J ˆ 6.9, Me2CH); 1.12, 1.08
.
‡
‡
‡
(2d, J ˆ 6.9, Me2CH). EI-MS: 494/492 (12/35, M ), 457 (56, [M Cl] ), 435/433 (21/68, [M MeOCO] ).
1.4. Dimethyl 9-Isopropyl-6-[(E)-2-(4-methoxyphenyl)ethenyl]-1-[(E)-2-(4-nitrophenyl)ethenyl]heptalene-
4,5-dicarboxylate (6b). The transformation of 5b (250 mg, 0.51 mmol) to 6b (150 mg, 50%) was performed as
described for 5a in 6a (see 1.2). Deep orange crystals. M.p. 174.6 ± 175.48 (Et2O). Rf (hexane/Et2O 1:1) 0.14.
UV/VIS (hexane, see also Fig. 1): lmax 442 (sh, 3.74), 380 (4.54), 328 (4.59), 287 (4.45); lmin 291 (4.45), 251
(4.35). IR (KBr): 2956w, 1718s, 1654w, 1592m, 1510s, 1436w, 1342s, 1254s, 1174w, 1087w, 1036w, 967w, 854w,
832w, 749w. 1H-NMR (300 MHz, CDCl3): 8.10 (d-like, 2 arom. H); 7.76 (d, J(2,3) ˆ 6.6, H C(3)); 7.45 (d-like, 2
arom. H); 7.23 (d-like, 2 arom. H); 7.10 (d, J ˆ 15.8, CHˆCH C(1)); 6.76 (d-like, 2 arom. H); 6.75 (d, J ˆ 16.0,
CHˆCH C(6)); 6.65 (d, J(2,3) ˆ 6.6, H C(2)); 6.60 (d, J ˆ 15.9, CHˆCH C(1)); 6.53 (m, H C(7,8)); 6.45
(d, J ˆ 16.1, CHˆCH C(6)); 5.98 (s, H C(10)); 3.75 (s, 2 MeOCO); 3.51 (s, MeO); 2.57 (sept., J ˆ 6.8,
Me2CH); 1.12, 1.10 (2d, J ˆ 6.8, Me2CH). 13C-NMR (75 MHz, CDCl3): 167.45, 166.91 (2s, MeOCO); 159.27 (s);
149.67 (s); 149.97 (s); 142.93 (s); 141.59 (s); 139.19 (d); 138.76 (s); 133.28 (d); 133.16 (s); 130.81 (s); 130.77 (d);
129.91 (d); 129.69 (s); 129.24 (d); 129.10 (d); 128.07 (d); 127.63 (d, 2 arom. C); 127.34 (d, 2 arom. C); 126.48 (s);
126.20 (s); 126.19 (d); 125.86 (d); 123.86 (d, 2 arom. C); 113.93 (d, 2 arom. C); 55.16 (q, MeO); 52.16, 52.01 (2q,
‡
MeOCO); 35.80 (d, Me2CH); 23.05, 22.22 (2q, Me2CH). CI-MS: 593 (37), 592 (100, [M ‡ 1] ), 560 (52, [M
‡
MeOH] ), 532 (43). Anal. calc. for C36H33NO7 (591.67): C 73.08, H 5.62, N 2.37; found: C 72.72, H 5.40, N 2.32.
1.5. 1-[(E)-2-Phenylethenyl]heptalene-4,5-dicarboxylates from the Corresponding 1-Methylheptalenes.
General Procedure. At 08, to the stirred soln. of the 1-methylheptalene-4,5-dicarboxylate (0.20 mmol) and
ArCHO (0.26 mmol) in THF (2.7 ml) was added 1m THF soln. of t-BuOK (0.26 ml, 0.26 mmol) dropwise. The
mixture was then left at 258, and stirring was continued for 90 min. The reaction was quenched by addition of an
aq. soln. of NH4Cl, and the mixture was then extracted with Et2O. The residue of Et2O extracts was
chromatographed (silica gel; hexane/Et2O/CH2Cl2 80 :5 :15), followed by recrystallization from CH2Cl2/hexane,
to yield pure 1-[(E)-2-phenylethenyl]heptalene-4,5-dicarboxylates.
1.5.1. Dimethyl 9-Isopropyl-6-methyl-1-[(E)-2-phenylethenyl]heptalene-4,5-dicarboxylate (10a) [4]. Hepta-
lene 9 (68.1 mg, 0.2 mmol) and PhCHO provided 10a (38 mg, 44%). Yellow crystals. M.p. 148.2 ± 150.08.
1.5.2. Dimethyl 9-Isopropyl-6-methyl-1-[(E)-2-(4-nitrophenyl)ethenyl]heptalene-4,5-dicarboxylate (10b).
Heptalene 9 (68.1 mg, 0.2 mmol) and 4-nitrobenzaldehyde provided 10b (8 mg, 8.4%). Yellow crystals. M.p.
213.4 ± 214.88 (CH2Cl2/hexane). Rf(hexane/Et2O 1:1) 0.25. 1H-NMR (300 MHz, CDCl3): 8.16 (d, J ˆ 8.8, 2
arom. H); 7.65 (d, J(2,3) ˆ 6.5, H C(3)); 7.49 (d, J ˆ 8.8, 2 arom. H); 7.10 (d, J ˆ 15.8, CHˆCH C(1)); 6.57
(d, J ˆ 15.8, CHˆCH C(1)); 6.54 (d, J(2,3) ˆ 6.5, H C(2)); 6.40 (d, J(7,8) ˆ 6.6, H C(7)); 6.32 (d, J(7,8) ˆ
6.6, H C(8)); 5.89 (s, H C(10)); 3.74, 3.72 (s, 2 MeOCO); 2.53 (sept., J ˆ 6.8, Me2CH); 1.09, 1.07 (2d, J ˆ 6.8,
.
‡
Me2CH). EI-MS: 474 (28), 473 (100, M ), 426 (15), 414 (26), 398 (42), 331 (62).
1.5.3. Dimethyl 6,8,10-Trimethyl-1-[(E)-2-phenylethenyl]heptalene-4,5-dicarboxylate (12a) [4]. Heptalene
11 (163 mg, 0.5 mmol) and PhCHO provided 12a (70 mg, 34%). Yellow crystals. M.p. 191 ± 192.28 ([4]: 192.5 ±
193.08).
1.5.4. Dimethyl 1-[(E)-2-(4-Methoxyphenyl)ethenyl]-6,8,10-trimethylheptalene-4,5-dicarboxylate (12b) [4].
Heptalene 11 (163 mg, 0.5 mmol) and 4-methoxybenzaldehyde provided 12b (60 mg, 27%) as yellow crystals.
M.p. 176 ± 176.78 ([4]:174.0 ± 175.08).
1.5.5. Dimethyl 8-(tert-Butyl)-10-methyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]-1-[(E)-2-phenylethenyl]hep-
talene-4,5-dicarboxylate (13) and 4-Benzyl 5-Methyl 8-(tert-Butyl)-10-methyl-6-[(1E,3E)-4-phenylbuta-1,3-
dienyl]-1-[(E)-2-phenylethenyl]heptalene-4,5-dicarboxylate (14). Heptalene
PhCHO afforded 13 (14 mg, 33%) and 14 (12 mg, 25%).
7 (36.2 mg, 0.075 mmol) and
Data of 13: yellow crystals. M.p. 118.2 ± 119.08 (hexane). Rf(hexane/Et2O 1:1) 0.30. UV/VIS (hexane; see
also Fig. 2): lmax 420 (sh, 3.80), 350 (sh, 4.60), 324 (4.65); lmin 256 (4.27). IR (KBr): 3024w, 2950w, 1719s, 1538w,
1435m, 1391w, 1260s, 1216w, 1194w, 1087w, 1053w, 987w, 774w, 751m, 691m. 1H-NMR (300 MHz, CDCl3)1): 7.76
(d, J(2,3) ˆ 6.5, H C(3)); 7.36 ± 7.10 (m, 10 arom. H); 6.92 (d, J ˆ 15.8, CHˆCH C(1)); 6.69 (dd, J(2',3') ˆ
10.5, J(3',4') ˆ 15.5, H C(3')); 6.64 (d, J(2,3) ˆ 6.2, H C(2)); 6.56 (s, H C(7)); 6.42 (d, J(3',4') ˆ 15.3,
H
C(4')); 6.39 (d, J(1',2') ˆ 15.5, H C(1')); 6.35 (d, J ˆ 16.0, CHˆCH C(1)); 6.32 (s, H C(9)); 6.19 (dd,
J(2',3') ˆ 10.5, J(1',2') ˆ 15.2, H C(2')); 3.75, 3.55 (2s, 2 MeOCO)); 1.68 (s, Me C(10)); 1.28 (s, t-Bu).
13C-NMR (75 MHz, CDCl3): 167.65, 167.24 (s, 2 MeOCO); 153.04 (s); 141.94 (s); 139.70 (s); 138.78 (d); 137.27

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Helvetica Chimica Acta ± Vol. 82 (1999)
(s); 136.77 (s); 134.06 (s); 133.03 (d); 132.97 (d); 132.79 (s); 131.51 (d); 131.35 (s); 129.83 (d); 129.26 (d); 128.84
(d); 128.48 (d, 2 arom. C); 128.44 (d, 2 arom. C); 128.12 (d); 127.95 (d); 127.30 (d); 127.11 (d); 126.92 (d, 2 arom.
C); 126.71 (d); 126.16 (d, 2 arom. C); 125.61 (s); 123.75 (s); 52.04, 51.75 (q, 2 MeOCO); 36.55 (s, Me3C); 30.30
‡
‡
(q, Me3C); 19.22 (q, Me C(10)). CI-MS: 588 (21, [M ‡ NH4] ), 572 (20), 571 (50, [M ‡ 1] ), 540 (39), 539
(100).
Data of 14: Yellow crystals. M.p. 120.3 ± 121.28 (hexane). Rf(hexane/Et2O 1:1) 0.41. UV/VIS (hexane; see
also Fig. 2): lmax 420 (sh, 3.75), 350 (sh, 4.60), 324 (4.67); lmin 256 (4.28). IR (KBr): 3025w, 2962w, 1717s, 1538w,
1496w, 1448w, 1252s, 1172w, 1084w, 1051w, 986w, 773w, 750m, 692m. 1H-NMR (300 MHz, CDCl3): 7.79 (d,
J(2,3) ˆ 6.5, H C(3)); 7.40 ± 7.10 (m, 15 arom. H); 6.91 (d, J ˆ 15.8, CHˆCH C(1)); 6.67 (dd, J(3',4') ˆ 15.5,
J(2',3') ˆ 10.5, H C(3')); 6.63 (d, J(2,3) ˆ 6.5, H C(2)); 6.55 (s, H C(7)); 6.40 (d, J(1',2') ˆ 15.1, H C(1'));
6.39 (d, J(3',4') ˆ 15.5, H C(4')); 6.38 (d, J ˆ 15.8, CHˆCH C(1)); 6.31 (s, H C(9)); 6.19 (dd, J(1',2') ˆ 15.1,
J(2',3') ˆ 10.5, H C(2')); 5.19 (s, PhCH2); 3.35 (s, MeOCO); 1.68 (s, Me C(10)); 1.28 (s, t-Bu). 13C-NMR
(75 MHz, CDCl3): 167.53, 166.53 (s, MeOCO and PhCH2OCO); 153.01 (s); 142.18 (s); 140.19 (s); 138.93 (d);
137.27 (s); 136.77 (s); 135.73 (s); 134.23 (s); 133.06 (d); 133.03 (d); 132.76 (s); 131.46 (s); 131.41 (d); 129.84 (d);
129.09 (d); 128.82 (d); 128.48 (d, 2 arom. C); 128.44 (d, 2 arom. C); 128.31 (d, 2 arom. C); 128.13 (d); 128.01 (d, 2
arom. C); 127.99 (d); 127.92 (d); 127.29 (d); 127.11 (d); 126.93 (d, 2 arom. C); 126.72 (d); 126.16 (d); 125.50 (s);
124.06 (s); 66.68 (t, PhCH2); 51.56 (q, MeOCO); 36.56 (s, Me3C); 30.29 (q, Me3C); 19.21 (q, Me C(10)). CI-
.
‡
‡
‡
MS: 664 (28, [M ‡ NH4] ), 648 (37), 647 (83, [M ‡ 1] ), 646 (9, M ), 616 (46), 615 (100).
1.5.6. Dimethyl 8,10-Dimethyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]-1-[(E)-2-phenylethenyl]heptalene-4,5-
dicarboxylate (16) and 4-Benzyl 5-Methyl 8,10-Dimethyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]-1-[(E)-2-phenyl-
ethenyl]heptalene-4,5-dicarboxylate (17). Heptalene 15 (35 mg, 0.08 mmol) and PhCHO afforded 16 (8 mg,
19%) and 17 (12 mg, 25%).
Data of 16: Yellow crystals. M.p. 117.2 ± 118.08 (CH2Cl2/hexane). Rf(hexane/Et2O 1:1) 0.31. UV/VIS
(hexane; see also Fig. 2): lmax 420 (sh, 3.60), 358 (4.55), 325 (4.61); lmin 351 (4.55), 257 (4.22). IR (KBr): 3022w,
2974w, 1717s, 1538w, 1496w, 1435m, 1259s, 1214w, 1194m, 1162w, 1088m, 1053w, 986w, 964m, 775w, 751m, 691m.
1H-NMR (600 MHz, CDCl3)1): 7.79 (d, J(2,3) ˆ 6.5, H C(3)); 7.34 (m, 2 arom. H); 7.29 (m, 2 arom. H); 7.26
(m, 2 arom. H); 7.25 (m, 2 arom. H); 7.20 (m, 1 arom. H); 7.16 (m, 1 arom. H); 6.93 (d, J ˆ 15.8, CHˆCH C(1));
6.70 (dd, J(3',4') ˆ 15.3, J(2',3') ˆ 10.6, H C(3')); 6.67 (d, J(2,3) ˆ 6.5, H C(2)); 6.42 (d, J(3',4') ˆ 15.2,
H
H
C(4')); 6.39 (d, J(1',2') ˆ 15.2, H C(1')); 6.36 (d, J ˆ 15.8, CHˆCH C(1)); 6.32 (s, H C(7)); 6.28 (s,
C(9)); 6.25 (dd, J(1',2') ˆ 15.2, J(2',3') ˆ 10.5, H C(2')); 3.76, 3.57 (s, 2 MeOCO); 2.18 (s, Me C(8)); 1.67
(s, Me C(10)). 13C-NMR (150 MHz, CDCl3): 167.90, 167.70 (s, 2 MeOCO); 142.54 (s); 140.03 (s); 140.02 (s);
139.54 (d, C(3)); 137.47 (s); 136.99 (s); 133.63 (d, C(4')); 133.40 (s); 133.14 (d, CHˆCH C(1)); 132.95 (s);
132.09 (d, C(9)); 131.98 (d, C(7)); 131.78 (d, C(1')); 131.64 (s); 130.52 (d, C(2')); 129.06 (d, C(3')); 128.79 (d, 2
atom. C); 128.77 (d, 2 aom. C); 128.60 (d, C(2)); 128.46 (d, 1 atom. C); 127.70 (d, 1 arom. C); 127.33 (d,
CHˆCH C(1)); 127.23 (d, 2 arom. C); 126.50 (d, 2 arom. C); 126.14 (s); 121.95 (s); 52.42, 52.12 (q, 2
‡
MeOCO); 25.55 (q, Me C(8)); 19.29 (q, Me C(10)). CI-MS: 547 (12), 546 (33, [M ‡ NH4] ), 530 (16), 529
‡
(46, [M ‡ 1] ), 498 (35), 497 (100).
Data of 17: Yellow crystals. M.p. 107 ± 1088. Rf(hexane/Et2O 1:1) 0.44. UV/VIS (hexane, see also Fig. 2):
lmax 420 (sh, 3.62), 358 (4.54), 325 (4.62); lmin 256 (4.31). IR (KBr): 3024w, 2946w, 1715s, 1654w, 1538w, 1497w,
1448w, 1435w, 1398w, 1246s, 1213m, 1192m, 1162m, 1077m, 1051w, 1028w, 986m, 964w, 773w, 751m, 692m.
1H-NMR (600 MHz, CDCl3)1): 7.84 (d, J(2,3) ˆ 6.5, H C(3)); 7.42 ± 7.16 (m, 15 arom. H); 6.94 (d, J ˆ 15.8,
CHˆCH C(1)); 6.70 (dd, J(3',4') ˆ 15.3, J(2',3') ˆ 10.5, H C(3')); 6.67 (d, J(2,3) ˆ 6.5, H C(2)); 6.42 (d,
J(3',4') ˆ 15.2, H C(4')); 6.40 (d, J(1',2') ˆ 15.2, H C(1')); 6.37 (d, J ˆ 15.8, CHˆCH C(1)); 6.33 (s,
H
C(7)); 6.30 (s, H C(9)); 6.25 (dd, J(1',2') ˆ 15.2, J(2',3') ˆ 10.5, H C(2')); 5.31, 5.15 (AB, JAB ˆ 12.4,
PhCH2); 3.37 (s, MeOCO C(5)); 2.20 (s, Me C(8)); 1.69 (s, Me C(10)). 13C-NMR (150 MHz, CDCl3):
167.75, 166.84 (s, MeOCO & PhCH2OCO); 142.66 (s); 140.00 (s); 140.01 (s); 139.72 (d, C(3)); 137.47 (s); 136.99
(s); 136.07 (s); 133.58 (d, C(4')); 133.38 (s); 133.16 (d, CHˆCH C(1)); 132.97 (s); 132.10 (d, C(9)); 131.97 (d,
C(7)); 131.76 (d, C(1')); 131.63 (s); 130.50 (d, C(2')); 129.06 (d, C(3')); 128.80 (d, 2 arom. C); 128.78 (d, 2 arom.
C); 128.75 (d, 2 arom. C); 128.60 (d, 2 arom. C); 128.58 (d, C(2)); 128.46 (d, 1 arom. C); 128.43 (d, 1 arom. C);
127.67 (d, 1 arom. C); 127.34 (d, CHˆCH C(1)); 127.23 (d, 2 arom. C); 126.48 (d, 2 arom. C); 126.21 (s);
122.01 (s); 67.11 (t, PhCH2); 51.99 (q, MeOCO); 25.52 (q, Me C(8)); 19.31 (q, Me C(10)). CI-MS: 622 (28,
.
‡
‡
‡
[M ‡ NH4] ), 606 (40), 605 (100, [M ‡ 1] ), 604 (25, M ), 574 (42), 573 (98), 497 (37).
1.6. 9-Isopropyl-5-(methoxycarbonyl)-1-methyl-6-[(E)-2-phenylethenyl]heptalene-4-carboxylic Acid (18).
The heptalene 4a (0.53 g, 1.24 mmol) and LiOH ´ H2O (1.84 g) were refluxed for 2 h in a mixture of MeOH
(75 ml) and H2O (11 ml). After cooling, 20 ml of H2O was added. Acidification with 2n aq. HCl, followed by
addition of another 100 ml of H2O, resulted in a yellow precipitate, which was isolated by filtration. Subsequent

Helvetica Chimica Acta ± Vol. 82 (1999)
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recrystallization from CH2Cl2/Et2O yielded 18 (0.50 g, 99%). Yellow crystals. M.p. 199.2 ± 199.88 (Et2O). UV/
VIS (CH2Cl2/hexane): lmax 410 (sh, 3.60), 350 (sh, 3.05), 306 (4.41), 260 (4.40); lmin 279 (4.25). IR (KBr):
2960m, 1718s, 1686s, 1596w, 1569w, 1435w, 1286m, 1195w, 1165w, 1050w, 964w, 789w, 751w, 694w. 1H-NMR
(300 MHz, CDCl3): 7.67 (dd, J(2,3) ˆ 6.4, J ˆ 0.9, H C(3)); 7.34 (m, 2 arom. H); 7.27 (m, 2 arom. H); 7.20 (m,
1 arom. H); 6.86 (d, J ˆ 16.1, CHˆCH C(6)); 6.56 (d, J ˆ 16.1, CHˆCH C(6)); 6.43, 6.40 (AB, JAB ˆ 6.9,
H
C(7), H C(8)); 6.34 (dd, J ˆ 1.4, J(2,3) ˆ 6.4, H C(2)); 5.94 (s, H C(10)); 3.48 (s, MeOCO); 2.53 (sept.,
J ˆ 6.8, Me2CH); 2.08 (s, Me C(1)); 1.12, 1.09 (2d, J ˆ 6.8, Me2CH). 13C-NMR (75 MHz, CDCl3): 171.67 (s,
COOH); 167.46 (s, MeOCO); 150.12 (s); 145.24 (s); 142.08 (d); 137.16 (s); 137.14 (s); 133.33 (s); 131.11 (s);
130.13 (s); 130.03 (d); 128.61 (d); 128.43 (d, 2 arom. C); 127.58 (d); 127.36 (d); 126.57 (d); 126.40 (d, 2 arom. C);
125.96 (d); 125.80 (d); 125.51 (s); 51.97 (q, MeOCO); 35.95 (d, Me2CH); 25.91 (q, Me C(1)); 22.91, 22.34 (2q,
.
‡
Me2CH). EI-MS: 415 (26), 414 (89, M ), 382 (29), 369 (86), 355 (100).
1.7. 8-Isopropyl-1,1-dimethoxy-6-methyl-11-[(E)-2-phenylethenyl]heptaleno[4,5-c]furan-3-one (19). Treat-
ment of 18 (250 mg, 0.60 mmol) in MeCN (2.7 ml) with the iminium salt from DMF (0.33 ml, 4.2 mmol) and
(COCl)2 (0.107 ml, 1.24 mmol) in MeCN (4 ml) was carried out as described in [10] [11] to yield 19 (206 mg,
80%). Deep orange crystals. M. p. 154.7 ± 155.88 (hexane). Rf(hexane/Et2O 1:1) 0.65. UV/VIS (hexane): lmax
420 (sh, 3.60), 348 (4.19), 303 (4.38), 262 (4.44); lmin 336 (4.18), 286 (4.33), 229 (4.31). IR (KBr): 2959w, 1772s,
1
1557w, 1287m, 1199w, 1162w, 1136w, 1061w, 962w, 919m, 809w, 779w. H-NMR (300 MHz, CDCl3): 7.40 (m, 2
arom. H); 7.33 (m, 2 arom. H); 7.31 (dd, J ˆ 0.7, J(4,5) ˆ 6.6, H C(4)); 7.23 (m, 1 arom. H); 6.95 (d, J ˆ 16.0,
CHˆCH C(11)); 6.74 (d, J ˆ 16.0, CHˆCH C(11)); 6.55 (d, J(9,10) ˆ 6.9, H C(10)); 6.45 (dd, J ˆ 1.4,
J(4,5) ˆ 6.6, H C(5)); 6.33 (d, J(9,10) ˆ 6.9, H C(9)); 5.81 (d, J ˆ 1.1, H C(7)); 3.31, 3.19 (2s, MeO C(1));
2.50 (sept., J ˆ 6.8, Me2CH); 2.19 (dd, J ˆ 0.6, J ˆ 1.4, Me C(6)); 1.10, 1.07 (2d, J ˆ 6.8, Me2CH). 13C-NMR
(75 MHz, CDCl3): 170.17 (s, C(3)); 151.67 (s); 139.94 (s); 137.39 (s); 136.03 (s); 134.03 (d); 132.21 (s); 130.39
(d); 130.04 (d); 129.50 (s); 129.34 (s); 129.25 (s); 128.45 (d, 2 arom. C); 127.99 (d); 127.81 (d); 127.39 (d); 126.98
(d); 126.45 (d, 2 arom. C); 124.73 (d); 119.03 (s, C(1)); 52.66, 50.50 (2q, MeO C(1)); 36.34 (d, Me2CH); 25.14
.
‡
(q, Me C(6)); 22.92, 22.59 (2q, Me2CH). EI-MS: 429 (16), 428 (61, M ), 369 (11), 121 (100). Anal. calc. for
C28H28O4 (428.53): C 78.48, H 6.59; found: C 78.60, H 6.57.
1.8. Methyl 4-Formyl-9-isopropyl-1-methyl-6-[(E)-2-phenylethenyl]heptalene-5-carboxylate (20). At 788,
to a stirred soln. of 19 (154 mg, 0.36 mmol) in toluene (13 ml) was added 1m DIBAH (0.36 ml, 0.36 mmol) in
hexane. After 10 min, TLC indicated that all the starting material had been consumed. MeOH and H2O were
added subsequently to quench the reaction. Extraction, followed by CC (silica gel; hexane/Et2O 3 : 1), yielded
19 (129 mg, 90%). Yellow crystals. M.p. 97.4 ± 99.08 (hexane). 1H-NMR (300 MHz, CDCl3): 9.44 (s, CHO); 7.35
(m, 2 arom. H); 7.28 (m, 2 arom. H); 7.21 (d, J(2,3) ˆ 6.1, H C(3)); 7.19 (m, 1 arom. H); 6.85 (d, J ˆ 16.1,
CHˆCH C(6)); 6.58 (d, J ˆ 16.1, CHˆCH C(6)); 6.45 (dd, J ˆ 1.3, J(2,3) ˆ 6.1, H C(2)); 6.41 (m, H C(7),
H
C(8)); 5.94 (s, H C(10)); 3.50 (s, MeOCO); 2.52 (sept., J ˆ 6.9, Me2CH); 2.12 (s, Me C(1)); 1.11, 1.07 (2d,
.
‡
J ˆ 6.9, Me2CH). EI-MS: 399 (27), 398 (100, M ), 369 (28), 339 (67).
1.9. Methyl 9-Isopropyl-1-methyl-4-[(1E,3E)-4-phenylbuta-1,3-dienyl]-6-[(E)-2-phenylethenyl]heptalene-
5-carboxylate (21a) and Methyl 7-Isopropyl-5-methyl-2-[(1E,3E)-4-phenylbuta-1,3-dienyl]-10-[(E)-2-phenyl-
ethenyl]heptalene-1-carboxylate (21b). The Wittig reaction of 20 (20 mg, 0.05 mmol) and (cinnamyl)(triphenyl)-
phosphonium bromide (138 mg, 0.30 mmol) was carried out as described in [9] to give 21a/21b (19 mg, 76%).
Data of 21a (in thermal equilibrium in CDCl3 at 258 with 10% of 21b): yellow crystals. M.p. 157.0 ± 158.38
2
(hexane). Rf (hexane/Et2O 1:1) 0.75. UV/VIS (hexane/CH2Cl2; see also Fig. 3) ): lmax 390, 340; lmin 320. IR
(KBr): 3024w, 2959m, 1714s, 1590w, 1494w, 1447w, 1432w, 1248m, 1216m, 1125w, 1053w, 989m, 748m, 691m.
1H-NMR (600 MHz, CDCl3, taken from the mixture with 21b)1): 7.37 (m, 4 arom. H); 7.28 (m, 4 arom. H); 7.19
(m, 2 arom. H); 6.88 (d, J ˆ 16.1, CHˆCH C(6)); 6.78 (dd, J(2',3') ˆ 8.9, J(3',4') ˆ 15.2, H C(3')); 6.62 (d, J ˆ
16.1, CHˆCH C(6)); 6.55 (d, J(2,3) ˆ 6.5, H C(3)); 6.51 (d, J(3',4') ˆ 15.5, H C(4')); 6.46 (d, J(7,8) ˆ 6.8,
H
C(8)); 6.43 (d, J(7,8) ˆ 6.8, H C(7)); 6.37 (m, H C(1'), H C(2'); 6.28 (dd, J ˆ 1.3, J(2,3) ˆ 6.5, H C(2));
5.94 (s, H C(10)); 3.48 (s, MeOCO); 2.55 (sept., J ˆ 6.9, Me2CH); 2.04 (s, Me C(1)); 1.13, 1.10 (2d, J ˆ 6.9,
‡
Me2CH). CI-MS: 500 (37), 499 (100, [M ‡ 1] ).
Data of 21b (in thermal equilibrium in CDCl3 at 258 with 90% of 21a): UV/VIS (hexane/CH2Cl2; see also
Fig. 3)2): lmax 415, 360, 290; lmin 315. H-NMR (600 MHz, CDCl3, taken from the mixture with 21a)1): 7.64 (d,
1
J(3',4') ˆ 15.5, H C(4')); 7.43 (m, 4 arom. H); 7.32 (m, 4 arom. H); 7.23 (m, 2 arom. H); 7.02 (dd, J(2',3') ˆ
10.7, J(1',2') ˆ 15.5, H C(2')); 6.93 (d, J ˆ 16.1, CHˆCH C(10)); 6.87 (d, J(3,4) ˆ 11.9, H C(4)); 6.79 (dd,
J(2',3') ˆ 10.7, J(3',4') ˆ 15.5, H C(3')); 6.78 (d, J(8,9) ˆ 10.9, H C(9)); 6.72 (d, J(1',2') ˆ 15.6, H C(1')); 6.59
2
)
UV/VIS Spectra recorded during HPLC (Waters, model 911) with the photodiode-array detector.

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Helvetica Chimica Acta ± Vol. 82 (1999)
(d, J ˆ 16.1, CHˆCH C(10)); 6.58 (d, J(3,4) ˆ 11.9, H C(3)); 6.54 (d, J(8,9) ˆ 10.9, H C(8)); 5.84 (s,
H
C(6)); 3.58 (s, MeOCO); 2.61 (sept., J ˆ 6.9, Me2CH); 1.84 (s, Me C(5)); 1.10, 0.99 (2d, J ˆ 6.9, Me2CH).
1.10. Dimethyl 9-Formyl-6-[(1E,3E)-4-phenylbuta-1,3-dienyl]heptalene-4,5-dicarboxylate (23): The mixture
of 22 (45 mg, 0.11 mmol) and SeO2 (45 mg, 0.32 mmol) in dioxane (2,5 ml) was heated at 1008 for 6 h. After
filtration, dioxane was removed to leave a orange residue, which was then subjected to CC (silica gel; hexane/
Et2O 1:1) to give 23 (29 mg, 62%). Orange crystals. M.p. 209.0 ± 210.38 (Et2O). Rf(hexane/AcOEt 4 :6) 0.59.
UV/VIS (hexane): lmax 440 (sh, 4.10), 368 (4.29), 330 (4.38), 284 (4.21), 244 (4.29); lmin 353 (4.28), 293 (4.19),
267 (4.14), 230 (4.25). IR (KBr): 2950w, 1717s, 1684s, 1596w, 1558w, 1501m, 1436w, 1272s, 1164m, 1128w, 1054w,
1
1004w, 893w, 752w, 714w, 692w. H-NMR (600 MHz, CDCl3)1): 9.55 (s, CHO); 7.69 (d, J(2,3) ˆ 6.4, H C(3));
7.39 (m, 2 arom. H); 7.32 (m, 2 arom. H); 7.25 (m, 1 arom. H); 7.24 (d, J(7,8) ˆ 7.0, H C(8)); 6.82 (dd,
J(3',4') ˆ 15.5, J(2',3') ˆ 10.7, H C(3')); 6.67 (d, J(3',4') ˆ 15.5, H C(4')); 6.63 (dd, J(1',2') ˆ 15.3, J(2',3') ˆ
10.4, H C(2')); 6.59 (d, J(7,8) ˆ 7.0, H C(7)); 6.55 (dd, J(1,2) ˆ 10.3, J(2,3) ˆ 6.4, H C(2)); 6.54 (d, J(1',2') ˆ
15.5, H C(1')); 6.30 (s, H C(10)); 6.26 (d, J(1,2) ˆ 10.2, H C(1)); 3.74, 3.57 (2s, MeOCO). 13C-NMR
3
(150 MHz, CDCl3) ): 192.70 (d, CHO); 167.22, 166.63 (2s, MeOCO); 144.82 (d, C(8)); 141.00 (d, C(3)); 139.47
(s); 137.60 (s); 136.94 (s); 136.71 (s); 136.51 (d, C(4')); 134.87 (d, C(1)); 134.07 (s); 133.22 (d, C(2')); 132.07 (d,
C(1')); 131.78 (d, C(2)); 131.37 (s); 128.71 (d, 2 arom. C); 128.27 (d, 1 arom. C); 128.05 (d, C(7)); 127.93 (d,
.
‡
C(3')); 126.63 (d, 2 arom. C); 124.49 (d, C(10)); 52.40, 52.23 (2q, MeOCO). EI-MS: 427 (27), 426 (100, M ),
‡
394 (22, [M CO] ), 367 (35), 335 (64).
1.11. Dimethyl 6,9-Bis[(1E,3E)-4-phenylbuta-1,3-dienyl]heptalene-4,5-dicarboxylate (24). The Wittig reac-
tion of 23 (27 mg, 0.053 mmol) with (cinnamyl)(triphenyl)phosphonium bromide (175 mg, 0.38 mmol) was
carried out as described in [9] to yield 24 (32 mg, 96%). Orange crystals. M.p. 181.2 ± 181.98 (hexane).
Rf(hexane/Et2O 1 :1) 0.27. UV/VIS (hexane; see also Fig. 4): lmax 450 (sh, 4.25), 368 (4.48), 249 (4.30); lmin 296
(4.04). IR (KBr): 3024w, 2948w, 1735s, 1599w, 1492w, 1436w, 1272s, 1124w, 1052w, 981m, 884w, 776w, 749m,
4
692w. 1H-NMR (600 MHz, CDCl3) ): 7.69 (d, J(2,3) ˆ 6.4, H C(3)); 7.38 (m, 4 arom. H); 7.30 (m, 4 arom. H);
7.21 (m, 2 arom. H); 6.87 (dd, J(3'',4'') ˆ 15.4, J(2'',3'') ˆ 10.5, H C(3'')); 6.81 (dm-like, J(3',4') ˆ 15.5,
H
C(3')); 6.60 (d, J(3'',4'') ˆ 15.5, H C(4'')); 6.58 (dd, J(1'',2'') ˆ 15.4, J(2'',3'') ˆ 10.5, H C(2'')); 6.57 (d,
J(3',4') ˆ 15.5, H C(4')); 6.53 (dd, J(1,2) ˆ 10.2, J(2,3) ˆ 6.3, H C(2)); 6.52 (d, J(7,8) ˆ 7.0, H C(8)); 6.48
(m, H C(1',2')); 6.43 (d, J(1'',2'') ˆ 15.5, H C(1'')); 6.42 (d, J(7,8) ˆ 7.0, H C(7)); 6.19 (d, J(1,2) ˆ 10.2,
H
C(1)); 6.08 (s, H C(10)); 3.73, 3.56 (2s, MeOCO). 13C-NMR (150 MHz, CDCl3): 167.50, 166.91 (2s,
MeOCO); 140.64 (s); 140.48 (d, C(3)); 138.65 (s); 137.27 (s); 137.21 (s); 135.34 (d, C(1'')); 134.60 (d, C(1));
134.27 (s); 133.91 (d, C(4')); 133.23 (d, C(1')); 133.17 (d, C(4'')); 132.55 (s); 131.15 (d, C(8)); 130.98 (d, C(2));
130.37 (s); 130.22 (d, C(7)); 129.90 (d, C(2')); 129.42 (d, C(2'')); 129.15 (d, C(3'')); 128.62 (d, C(3')); 128.61 (d, 4
arom. C); 127.63 (d, 1 arom. C); 127.58 (d, 1 arom. C); 126.97 (s); 126.40 (d, C(10)); 126.36 (d, 2 arom. C);
‡
‡
126.34 (d, 2 arom. C); 52.30, 52.13 (2q, MeOCO). CI-MS: 544 (32, [M ‡ NH4] ), 527 (100, [M ‡ 1] ), 526 (8,
.
‡
M
), 499 (23).
2. X-Ray Crystal-Structure Determination ) of 24. ± The calculations for 24 were performed using the
5
TEXSAN crystallographic software package. The data collection and refinement parameters are given in the
Table. For other experimental detail, see [9].
REFERENCES
[1] S. El Houar, H.-J. Hansen, Helv. Chim. Acta 1997, 80, 253.
[2] S. Maillefer-El Houar, Ph. D. Thesis, University of Zürich, 1998; S. Maillefer-El Houar, H.-J. Hansen, Helv.
Chim. Acta, in preparation.
[3] J. Song, H.-J. Hansen, Helv. Chim. Acta 1999, 82, 309.
[4] A. A. S. Briquet, H.-J. Hansen, Helv. Chim. Acta 1994, 77, 1940.
[5] B. Basu, S. Bhattacharyya, D. Mukherjee, Tetrahedron Lett. 1984, 25, 1195.
3
)
)
One quaternary-C signal was hidden under the other signals.
The C-atoms of the buta-1,3-dienyl side chain at C(6) are indicated with primed numbers, and those of the
buta-1,3-dienyl moiety at C(9) with double-primed numbers.
Crystallographic data (excluding structure factors) for the structures of compounds 24 have been deposited
with the Cambridge Crystallographic Data Centre as supplementary publication No. CCDC-134038. Copies
of the data can be obtained, free of charge, on application to the CCDC, 12 Union Road, Cambridge
CB21EZ, UK (fax: ‡ 44-(0)-1223-336033 or e-mail: deposit@ccdc.cam.ac.uk).
4
5
)

Helvetica Chimica Acta ± Vol. 82 (1999)
2273
Table. Crystallographic Data of 24
24
Crystallized from
CH2Cl2/Et2O/hexane
C36H30O4 ´ 0.5 CH2Cl2
569.10
Empirical formula
Formula weight [g mol
Crystal color, habit
1
]
Red, prism
Crystal dimensions [mm]
Temp. [K]
0.25 Â 0.28 Â 0.48
173(1)
Crystal system
Space group
triclinic
P 1
Å
Z
2
Reflections for cell determination
25
2q Range for cell determination [8]
Unit cell parameters a [Š]
33 ± 38
11.656(2)
14.135(2)
9.762(2)
102.73(1)
99.51(1)
85.40(1)
1545.6(5)
1.223
b [Š]
c [Š]
a [8]
b [8]
g [8]
V [Š3]
3
Dx [g cm
]
3
m(MoKa) [mm
2q (max) [8]
]
0.161
55
Total reflections measured
Symmetry-independent reflections
Reflections used [I > 2s(I)]
Parameters refined
Final R
7434
7087
4617
398
0.0723
0.0705
3.483
wR
Goodness of fit
6
Secondary extinction coefficient
1.04(8) Â 10
0.0002
0.56; 0.48
0.004 ± 0.01
Final Dmax/s
Dr (max; min) [e Š
s (d(C C)) [Š]
3
]
[6] T. Miwa, T. Hitaka, H. Nomura, J. Med. Chem. 1991, 34, 555.
[7] E. V. Dehmlow, A. R. Shamount, J. Chem. Res. Miniprint. 1981, 1178.
[8] A. A. S. Briquet, P. Uebelhart, H.-J. Hansen, Helv. Chim. Acta 1996, 79, 2282.
[9] J. Song, H.-J. Hansen, Helv. Chim. Acta, 1999, 82, 1690.
[10] R. H. Weber, P. Brügger, T. A. Jenny, H.-J. Hansen, Helv. Chim. Acta 1987, 70, 742.
[11] R. H. Weber, P. Brügger, W. Arnold, P. Schönholzer, H.-J. Hansen, Helv. Chim. Acta 1987, 70, 1439.
Received August 25, 1999