Synthesis of 6-styrylheptalenes

Article abstract of DOI:10.1002/(SICI)1522-2675(19991006)82:10<1690::AID-HLCA1690>3.0.CO;2-D

4-Methylazulenes 3, 15, and 23 were transformed into 4- [(methylthio)methyl]azulene 4, and azulene-4-carbaldehyde dimethyl dithioacetals 16 and 24, respectively. Vilsmeier formylation of 4 and 16, and subsequent reduction led to the 1-methyl derivatives 6 and 18, respectively. The thermal reaction of azulenes 6, 18, and 24 with dimethyl acetylenedicarboxylate (ADM) in toluene afforded heptalenes with a (methylthio)methyl group or a [bis(methylthio)]methyl group at C(6). Chlorination of [(methylthio)methyl]heptalene 7, followed by treatment with HgO and BF₃ · OEt₂ in aqueous tetrahydrofuran (THF), led to 6- formylheptalene-dicarboxylate 12 in excellent yield. Similarly, hydrolysis of 18 and 24 by HgO and BF₃ · OEt₂ in aqueous THF afforded the 6-formyl derivatives 21 and 27, respectively. Wittig reaction of the 6-formyl- substituted heptalenes and phosphonium salts 13a-e in the two-phase system CH₂Cl₂/2N aqueous NaOH resulted in the formation of 6-styryl-substituted heptalenes.

Full text of DOI:10.1002/(SICI)1522-2675(19991006)82:10<1690::AID-HLCA1690>3.0.CO;2-D

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Helvetica Chimica Acta ± Vol. 82 (1999)
Synthesis of 6-Styrylheptalenes
by Jianfeng Song and Hans-Jürgen Hansen*
Organisch-chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich
4-Methylazulenes 3, 15, and 23 were transformed into 4-[(methylthio)methyl]azulene 4, and azulene-4-
carbaldehyde dimethyl dithioacetals 16 and 24, respectively. Vilsmeier formylation of 4 and 16, and subsequent
reduction led to the 1-methyl derivatives 6 and 18, respectively. The thermal reaction of azulenes 6, 18, and 24
with dimethyl acetylenedicarboxylate (ADM) in toluene afforded heptalenes with a (methylthio)methyl group
or a [bis(methylthio)]methyl group at C(6). Chlorination of [(methylthio)methyl]heptalene 7, followed by
treatment with HgO and BF3 ´ OEt2 in aqueous tetrahydrofuran (THF), led to 6-formylheptalene-dicarboxylate
12 in excellent yield. Similarly, hydrolysis of 18 and 24 by HgO and BF3 ´ OEt2 in aqueous THF afforded the 6-
formyl derivatives 21 and 27, respectively. Wittig reaction of the 6-formyl-substituted heptalenes and
phosphonium salts 13a ± e in the two-phase system CH2Cl2/2n aqueous NaOH resulted in the formation of 6-
styryl-substituted heptalenes.
Introduction. ± Several years ago, we reported on the thermal and Ru-catalyzed
reactions of styryl-substituted azulenes with dimethyl acetylenedicarboxylate (ADM),
which led to corresponding styryl-substituted heptalenes [1]. 7-Isopropyl-1-methyl-4-
[(E)-styryl]azulene, as well as its 4-methoxystyryl derivative, were reacted with ADM
under catalytic conditions to give the corresponding dimethyl 9-isopropyl-1-methyl-6-
styrylheptalene-4,5-dicarboxylate in ca. 30% yield, which is still much poorer than that
of the reaction between guaiazulene and ADM [2]. However, because of the difficult
access of other 4-styryl-substituted azulenes [3][4], the other type of 6-styryl-
substituted heptalenes remained inaccessible.
Recently, we found a simple and efficient method to obtain 4-styrylazulenes [5],
which opened the way for the synthesis of 6-styryl-substituted heptalenes. Unfortu-
nately, the reaction of 6-(tert-butyl)-1,8-dimethyl-4-[(E)-2-phenylethenyl]azulene (1)
with ADM, either under thermal or Ru-catalysis conditions, led only to trace amounts
of heptalene-4,5-dicarboxylates, which were evidenced on TLC by their typical Rf value
and pale yellow color (Scheme 1). This implies that styryl substituents at C(4) of
azulenes seriously hinder the formation of heptalenes-4,5-dicarboxylates from azulenes
and ADM. Since a Me group at C(6) of heptalene-dicarboxylates is difficult to
functionalize, there is no direct way to introduce a p-substituent at a Me C(6) moiety
of heptalenes starting from corresponding 6-Me derivatives. An alternative solution
would be to introduce a precursory group at C(4) of the azulenes, which should easily
react with ADM to provide, in a reasonable yield, the corresponding heptalenes with a
precursory group at C(6). This precursor should be easily transformed in the
subsequent step into a p-substituent. In this paper, we report on the synthesis of such
6-styrylheptalenes via (methylthio)- or bis(methylthio)methyl groups at C(6) of the
heptalenes.

Helvetica Chimica Acta ± Vol. 82 (1999)
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Scheme 1
Results and Discussions. ± Azulene 3 was deprotonated at one of the Me groups by
lithium diisopropylamide (LDA) in THF at 788. The carbanion formed was reacted
with dimethyl disulfide (MeSSMe) to give 8-[(methylthio)methyl]azulene 4 in
excellent yield (Scheme 2). The Vilsmeier formylation of 4 resulted in the two isomers
5a and 5b, which were easily separated by column chromatography on silica gel. The
distinction between the two isomers was achieved by 1H-NOE measurements. Only 5a
showed strong reciprocal effects on the signal of Me C(8) and the signal of the H-
atom of CHO C(1). The reduction of 5a proceeded smoothly by NaBH4 in a mixture
of trifluoroacetic acid (TFA) and CH2Cl2 to give azulene 6 in almost quantitative yield.
The procedure established by Anderson and Breazeale [6] (NaBH4/BF3 ´ OEt2 in
diglyme) led also to the same product 6, but in a much poorer yield (< 30%). The
Scheme 2
a) 7% of 5a was recovered.

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thermal reaction of azulene 6 with ADM in toluene afforded 6-[(methylthio)methyl]-
heptalene-dicarboxylate 7 in 15% yield, accompanied by azulene-dicarboxylates which
were not isolated.
In our first attempt to transform the MeSCH2 group into a styryl substituent, we
followed the methods reported by Hafner, Hünig, and co-workers [3][7]. The
methylation of 7 led to dimethylsulfonium tetrafluoroborate 8, which unfortunately did
not react with Ph3P to give the phosphorus salt 10a (Scheme 3). We assume that the
dimethylsulfonium moiety was not a good leaving group. Therefore, the 6-(iodome-
thyl)heptalene 9 was prepared in 82% yield by heating 7 with MeI in MeCN at 608 for
20 h. Again, heptalene 9 could not be converted either to phosphorous salt 10b or to
phosphonate 11 by reaction with P(OEt)3. Steric hindrance and poor nucleophilicity of
Ph3P and P(OEt)3 may account for the failure of these transformations.
Scheme 3
The other route involved conversion of the MeSCH2 group to a CHO function by
the method of Gassman et al. [8][9]. For this purpose, heptalene 7 was chlorinated with
N-chlorosuccinimide (NCS) in CCl4, followed by hydrolysis with HgO and BF3 ´ OEt2
in aqueous THF to give 6-formylheptalene-dicarboxylate 12 in almost quantitative
yield (Scheme 4).
There are several routes to transform a CHO function into a styryl group. It is
noteworthy that Wittig-Horner reaction with 12 gave 6-styrylheptalene derivatives 2a ±
b in only poor yields (< 20%). We assume that the neighboring MeOCO C(5)
trapped the formed oxy anion arising from CHO C(6) during the reaction since
MeOCO C(5) is very close to CHO C(6) (see Fig. 1 and the corresponding
discussion). By this side reaction, the formation of the styryl CˆC is blocked. This
effect may also account for the relatively poor yield of heptalene 2b in an established
Wittig reaction in the presence of t-BuOK in THF. However, in the two-phase system
CH2Cl2/2n aqueous NaOH, the Wittig reaction was completed within 2 h to give a
mixture of (1E,3E)-2e and (1Z,3E)-2e, which could be isomerized to pure (1E,3E)-2e

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Scheme 4
a) 26% of 12 was recovered.
by treatment with a catalytic amount of I2 at room temperature. The reaction between
12 and 13a was relatively slow and incomplete, and 26% of 12 was recovered, although
66% of styryl derivative 2a was obtained. On the other hand, the reaction of (4-
methoxybenzyl)triphenylphosphonium chloride (13b) and 12 gave only trace amounts
of 2b. When the ylide of 13b was prepared in t-BuOK/THFat 08, and added to the two-
phase system, the typical red color of the ylide disappeared immediately, but no
heptalene 2b could be detected. This experiment demonstrated that the ylide of 13b is
not stable in the two-phase system. The reaction between 13c and 12 proceeded
smoothly to give, in 82% yield, the mixture cis-2c/trans-2c. This mixture gave, in the
presence of catalytic amounts of I2, only in boiling toluene quantitatively the pure
trans-form, in contrast to the cis/trans-mixture of 2a and 2e, which isomerized to the

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pure trans-form already at room temperature. The reaction of the very stable ylide from
13d with 12, even after the addition of more equivalents of 13d and prolongation of the
reaction time, yielded only 15% of 2d, and 26% of starting material 12 could be
recovered. This indicates that the two-phase Wittig reaction worked well for the pre-
paration of 2a, 2c, and 2e. However, it was very sensitive to the strong electron-donor
or -acceptor functional groups on the aromatic ring of triphenylphosphonium salt 13.
Fortunately, we found that 6-[(E,E)-4-phenylbuta-1,3-dienyl]heptalene-dicarboxylate
2e could also be prepared in 87% yield by a Wittig-Horner reaction; however, it should
be considered an exceptional case. As a more general method to prepare the (buta-1,3-
dienyl)-substituted heptalenes, iodomethylenation [10] of 12 with CHI3/CrCl2 followed
by Heck reaction [11] in the presence of styrene led to 2e in 56% yield. Re-
placement of styrene by any substituted styrene in the Heck reaction should lead to the
corresponding [4-(X-phenyl)buta-1,3-dienyl]heptalene derivatives, since the Heck re-
action is not affected by the electronic properties of the substituents at the styrene [12].
For 4,6,8-trimethylazulene (15) with Me groups at both reactive positions, we had to
solve the problem of regioselectivity. When the reaction is carried out in THF [13] or
DMF [4], the formation of azulenes modified at C(6) rather than at C(4) has been
reported. Hafner, Hünig, and co-workers [7] found that 15 is deprononated exclusively
at Me C(4/8) with sodium N-methyl-N-phenylamide in Et2O at 208. The formed
sodium azulenide was isolated and then reacted with MeSSMe in Et2O at 258 to give
selectively the C(4)-modified product. The preparation of sodium N-methyl-N-
phenylamide in Et2O is laborious, and, last but not least, the whole procedure is very
complicated. When we used LDA to deprotonate 4,6,8-trimethylazulene (15) in Et2O/
hexane at 158, followed directly by addition of MeSSMe, the mixture of 4- and 6-
1
modified azulenes was obtained in a ratio of 85 : 15 according to H-NMR analysis.
When 1 equiv. of sodium bis(trimethylsilyl)amide was employed in the deprotonation
reaction in Et2O/toluene, without isolation of the formed sodium salt, the addition of
MeSSMe at 258 gave preferentially the 4-modified azulene (ratio according to
1H-NMR anaylsis: 95 : 5). Finally, we found that treatment of 15 with 2 equiv. of
sodium bis(trimethylsilyl)amide and 2 equiv. of MeSSMe led in one step to dimethyl
dithioacetal 16 in 60% yield (Scheme 5). The Vilsmeier formylation of 16 again
resulted in the formation of two isomeric carbaldehydes 17a and 17b, which were
separated by column chromatography on silica gel. The structure assignment of 17a
and 17b is based on 1H-NOE measurement. Only 17a showed strong reciprocal effects
on the signal of the Me group at C(8) and the signal of the H-atom of the CHO group at
C(1). The reduction of 17a by NaBH4 in TFA/CH2Cl2 led to a mixture of the desired
product 18 and the partially dethiolated product 19. Although 18 and 19 can be
recognized on TLC, any attempt to separate the mixture either by column
chromatography on silica gel or by preparative TLC failed. Since all other reduction
methods either under basic [14] or acidic conditions [15] affected the thioacetal group,
we were not able to obtain 18 without formation of 19. Finally, 18 was found to
crystallize much easier than 19 from hexane, and the fractional crystallization afforded
pure 18 in 52% yield. The thermal reaction of azulene 18 and ADM in toluene gave
heptalene-dicarboxylate 20a in 30% yield as a yellow crystals and its DBS (double-bond
shifted) isomer 20b in 5% yield as a yellow oil. Both compounds were separated by
column chromatography. It is easy to distinguish 20a from 20b by the difference of their

Helvetica Chimica Acta ± Vol. 82 (1999)
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Scheme 5
a) The yield was determined by 1H-NMR spectroscopy of the mixture of 18 and 19, from which pure 18
(52%) was isolated by recrystallization.
chemical shifts and coupling constants, e.g., 20a showed H C(2) and H C(3) as an
AB system with fine structure at 6.34 and 7.57 ppm with J(2,3) ˆ 5.9 Hz, whereas 20b
exhibited the signals of H C(3) and H C(4) as an AB system at 6.86 and 6.81 ppm
with J(3,4) ˆ 11.8 Hz. The hydrolysis of 20a with 2 equiv. of HgO and BF3 ´ OEt2 in
aqueous THF [9] led to formylheptalene-dicarboxylate 21 in 88% yield. It is interesting

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to note that hydrolysis of 20b as well afforded 21 in 68% yield, indicating that the
thermal equilibrium of 21 with its DBS isomer is at ambient temperature to >99% on
the side of 21. In the two-phase system CH2Cl2/2n NaOH, the Wittig reaction was
complete within 2 h to give the mixture (1E,3E)-22/(1Z,3E)-22. The latter was
transformed to pure (1E,3E)-22 by treatment with a catalytic amount of I2 in hexane/
Et2O at room temperature overnight.
Under the same conditions as described above, 4,7-dimethylazulene (23) was
converted to bis(methylthio)methyl-substituted azulene 24 in 44% yield (Scheme 6).
Heating 24 with ADM in toluene gave the heptalene 25 in 23% yield together with its
structural isomers 26a/26b (3.6%). Hydrolysis of 25 readily provided formylheptalene-
Scheme 6
a) At room temperature, 26a is in thermal equilibrium with 35% of its DBS isomer 26b (CDCl3).

Helvetica Chimica Acta ± Vol. 82 (1999)
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Fig. 1. Stereoscopic view of the X-ray crystal structure of heptalene 12
Fig. 2. Stereoscopic view of the X-ray crystal structure of heptalene 27
dicarboxylate 27 in excellent yield. Compounds 27 and 12 resemble each other in that
the CHO C(6) and MeOCO C(5) moieties are close together in both compounds (see
Figs. 1 and 2). Indeed, the distance between the O-atom of the CHO C(6) moiety and
the carbonyl C-atom of the MeOCO C(5) moiety is in both heptalenes 3.00 Š. In turn,
the distance of the carbonyl C-atom of the CHO C(6) moiety and the O-atom of the
MeO group of the MeOCO C(5) moiety (see Fig. 1), or the O-atom of the carbonyl C-
atom of the MeOCO C(5) (see Fig. 2), respectively, is also 3.00 Š in both heptalenes. In
other words, the trajectory for a nucleophilic attack at CHO is strongly impeded on one
of the diastereotopic sites, and the carbonyl C-atom of the MeOCO C(5) moiety is in
a optimal position to intermolecularly trap the evolving oxy anion at CHO C(6) in the
course of a nucleophilic attack. Nevertheless, applying Wittig-Horner reaction to 27
resulted in only trace amounts of heptalene-dicarboxylate 28. Whereas, under the same
conditions, styryl derivative 2e was obtained in 86% in the case of formylheptalene-
dicarboxylate 12 (Scheme 4). On the other hand, in the two-phase system CH2Cl2/2n
NaOH, the Wittig reaction with (cinnamyl)triphenylphosphonium salt and isomer-
ization transformed 27 into 28 in 95% yield (Scheme 6). Iodomethylenation of 27,
followed by the Heck reaction with styrene, resulted only in a yield of 38% of 28.
The (1E,3E)-configuration of the 4-phenylbuta-1,3-dienyl chain of 28 could not be
1
deduced from its H-NMR spectrum, since the signals of H C(1) and H C(2) were
too close together at 6.45 ppm. Finally, the (1E,3E)-configuration was confirmed by an
X-ray crystal-structure analysis of 28 (Fig. 3).

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Fig. 3. Stereoscopic view of the X-ray crystal structure of heptalene 28
The successful syntheses of 6-styrylheptalenes offered important intermediates to
introduce a second p-substituent in the heptalene ring to form various bis-p-substituted
heptalenes for the investigations of their DBS behavior [16].
We thank Dr. A. Linden for the X-ray crystal-structure analyses, Prof. M. Hesse and his co-workers for mass
spectra, our NMR department for NMR support and 2D-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 [5].
1. Syntheses of Azulenes and Heptalenes. ± 1.1. 6-(tert-Butyl)-8-methyl-4-[(methylthio)methyl]azulene (4).
At 788, to a stirred soln. of LDA (32.5 mmol; prepared from BuLi soln. (20.3 ml, 32.5 mmol) and (i-Pr)2NH
(6.8 ml, 48 mmol) in THF (110 ml), azulene 3 (5.31 g, 25 mmol) was added slowly. After the temp. was raised to
208 and kept there for 10 min, the mixture was cooled again to 788, followed by addition of MeSSMe
(2.44 ml, 27.5 mmol). The reaction was quenched by H2O after the mixture was warmed to 258 in 4 h. Extraction
by hexane and CC (silica gel; hexane) yielded 4 (5.43 g, 85%). Blue crystals. M.p. 78.0 ± 78.68 (hexane). Rf
(hexane/Et2O 95 : 5) 0.42. UV/VIS (hexane): lmax 550 (3.23), 350 (3.79), 289 (4.68), 247 (4.46); lmin 447 (3.15),
325 (3.67), 260 (4.01), 225 (4.21). IR (KBr): 2963s, 1576s, 1490s, 1458w, 1433m, 1360m, 1336m, 1241m, 1218m,
1174w, 1158w, 1094w, 1070w, 1014w, 960w, 906w, 870m, 762s, 736w, 716w. 1H-NMR (300 MHz, CDCl3): 7.71
(t, J(1,2) ꢀ J(2,3) ˆ 3.9, H C(2)); 7.45 (d, J ˆ 1.6, H C(5)); 7.41 (dd, J(1,3) ˆ 1.4, J(1,2) ˆ 3.9, H C(1)); 7.37
(d, J(1,3) ˆ 1.4, J(2,3) ˆ 3.9,
H C(3)); 7.33 (s, H C(7)); 4.27 (s, MeSCH2); 2.93 (s, Me C(8)); 2.07
(s, MeSCH2); 1.48 (s, t-Bu). 13C-NMR (75 MHz, CDCl3): 158.15 (s); 145.22 (s); 144.39 (s); 136.71 (s); 135.95
(s); 133.59 (d); 124.23 (d); 122.87 (d); 116.12 (d); 115.07 (d); 40.90 (t, MeSCH2); 38.68 (s, Me3C); 31.99
‡
(q, Me3C); 25.76 (q, Me C(8)); 16.04 (q, MeSCH2). CI-MS: 259 (100, [M ‡ 1] ), 213 (32). Anal. calc. for
C17H22S (258.43): C 79.00, H 8.58; found: C 78.93, H 8.42.
1.2. 6-(tert-Butyl)-8-methyl-4-[(methylthio)methyl]azulene-1-carbaldehyde (5a) and 6-(tert-Butyl)-8-meth-
yl-4-[(methylthio)methyl]azulene-3-carbaldehyde (5b). The Vilsmeier formylation of 4 (11.63 g, 45 mmol) was
performed as described in [5] to yield, after CC (silica gel; hexane/Et2O/CH2Cl2 80 :5 :15), 5b (3.6 g, 28%) as a
first fraction and 5a (7.6 g, 59%) as a second fraction.
Data of 5a: Violet crystals. M.p. 111.6 ± 112.48 (Et2O). Rf (hexane/Et2O 1:1) 0.38. UV/VIS (hexane): lmax
525 (3.21), 387 (4.00), 316 (4.60), 249 (4.38); lmin 430 (3.08), 349 (3.08), 272 (3.96). IR (KBr): 2954w, 1625s,
1576w, 1544w, 1497w, 1429w, 1353m, 1336m, 1245w, 1217w, 1065w, 800w, 771w, 729w. 1H-NMR (600 MHz,
CDCl3): 10.60 (s, CHO); 8.32 (d, J(2,3) ˆ 4.6, H C(2)); 7.73 (d, J ˆ 1.3, H C(5)); 7.67 (s, H C(7)); 7.38
(d, J(2,3) ˆ 4.6, H C(3)); 4.27 (s, MeSCH2); 3.23 (s, Me C(8)); 2.08 (s, MeSCH2); 1.50 (s, t-Bu). 1H-NOE:
CHO ! H C(2), Me C(8); MeSCH2 ! H C(5),
H
C(3); Me C(8) ! CHO,
H
C(7). 13C-NMR
(75 MHz, CDCl3): 186.74 (d, CHO); 159.96 (s); 148.07 (s); 146.82 (s); 142.28 (s); 138.74 (d); 137.74 (s);

Helvetica Chimica Acta ± Vol. 82 (1999)
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130.64 (d); 130.20 (s); 128.23 (d); 116.43 (d); 41.63 (t, MeSCH2); 38.81 (s, Me3C); 31.79 (q, Me3C); 31.60
.
‡
‡
(q, Me C(8)); 16.07 (q, MeSCH2). EI-MS: 287 (21), 286 (100, M ), 271 (16, [M Me] ), 240 (49), 212 (64).
Anal. calc. for C18H22OS (286.44): C 75.48, H 7.74; found: C 75.21, H 7.60.
Data of 5b: Violet crystals. M.p. 89.6 ± 90.28 (Et2O). Rf (hexane/Et2O 1:1) 0.50. UV/VIS (hexane): lmax 518
(3.30), 388 (4.02), 316 (4.59), 249 (4.42), 226 (4.44); lmin 429 (3.05), 351 (3.91), 274 (4.00), 237 (4.34). IR (KBr):
2960w, 1631s, 1578w, 1543w, 1498w, 1464w, 1420w, 1335s, 1243m, 1094w, 1050w, 883w, 796w, 770w. 1H-NMR
(600 MHz, CDCl3): 10.40 (s, CHO); 8.24 (d, J(1,2) ˆ 4.4, H C(2)); 7.80 (d, J ˆ 2.0, H C(5)); 7.64 (s, J ˆ 1.3,
H
C(7)); 7.31 (d, J(1,2) ˆ 4.4, H C(1)); 4.68 (s, MeSCH2); 2.96 (s, Me C(8)); 2.03 (s, MeSCH2); 1.50 (s, t-
Bu). 1H-NOE: CHO ! H C(2), MeSCH2; MeSCH2 ! CHO, H C(5); Me C(8) ! H C(7), H C(1).
13C-NMR (75 MHz, CDCl3): 186.74 (d, CHO); 160.27 (s); 148.46 (s); 147.75 (s); 144.04 (s); 141.95 (d); 135.71
(s); 129.53 (2d); 128.32 (s); 116.93 (d); 44.61 (t, MeSCH2); 38.85 (s, Me3C); 31.78 (q, Me3C); 26.89
.
‡
‡
(q, Me C(8)); 15.80 (q, MeSCH2). EI-MS: 287 (17), 286 (100, M ), 271 (20, [M Me] ), 238 (78). Anal.
calc. for C18H22OS (286.44): C 75.48, H 7.74; found: C 75.32, H 7.57.
1.3. 6-(tert-Butyl)-1,8-dimethyl-4-[(methylthio)methyl]azulene (6). Carbaldehyde 5a (2.58 g, 9.0 mmol) was
reduced by NaBH4 according to the procedure described in [5] to yield 0.19 g (7.4%) of the starting material 5a
and 2.20 g (90%) of 6 as blue crystals. Rf (hexane/Et2O 95 :5) 0.43. UV/VIS (hexane): lmax 581 (2.68), 355
(3.68), 290 (4.68), 249 (4.41); lmin 421 (1.63), 265 (3.99), 226 (4.06). IR (KBr): 2963s, 1573s, 1512m, 1441m,
1362w, 1340w, 1243m, 1198w, 1174w, 1042w, 948w, 860w, 784w, 719w. 1H-NMR (600 MHz, CDCl3): 7.50
(d, J(2,3) ˆ 4.0,
H
C(2)); 7.32 (d, J(2,3) ˆ 4.0,
H C(3)); 7.23 (s, H C(5)); 7.11 (s, H C(7)); 4.21
(s, MeSCH2); 3.07 (s, Me C(8)); 2.88 (s, Me C(1)); 2.10 (s, MeSCH2); 1.46 (s, t-Bu). 13C-NMR (75 MHz,
CDCl3): 157.71 (s); 146.86 (s); 143.82 (s); 137.83 (s); 136.59 (s); 133.59 (s); 126.90 (s); 124.93 (d); 121.60 (d);
113.82 (d); 41.36 (t, MeSCH2); 38.35 (s, Me3C); 31.60 (q, Me3C); 28.27 (q); 19.59 (q); 16.14 (q). EI-MS: 273
.
‡
‡
(20), 272 (100, M ), 257 (29, [M Me] ), 226 (73).
1.4. Dimethyl 8-(tert-Butyl)-1,10-dimethyl-6-[(methylthio)methyl]heptalene-4,5-dicarboxylate (7). Azulene
6 (2.20 g, 8.1 mmol) and ADM (3.64 g, 25.6 mmol) in toluene (85 ml) were heated at 1308 for 30 h. After
removal of toluene under reduced pressure, CC (silica gel; hexane/Et2O/CH2Cl2 80 :5 :15), followed by
recrystallization from CH2Cl2/hexane gave 7 (0.517 g, 15.4%). Yellow crystals. M.p. 154.1 ± 155.48 (hexane). Rf
(hexane/Et2O 1:1) 0.47. UV/VIS (hexane): lmax 314 (sh, 3.68), 264 (4.22); lmin 250 (4.21). IR (KBr): 2947w,
1718s, 1573w, 1435w, 1304w, 1272m, 1254m, 1198w, 1152w, 1098w, 1082w, 1050w, 783w, 768w. 1H-NMR
(300 MHz, CDCl3): 7.51 (dd, J(2,3) ˆ 6.1, 5J(3, Me C(1)) ˆ 0.8, H C(3)); 6.29 (s, H C(7)); 6.27 (dd, J(2,3) ˆ
6.1, 4J(2 Me C(1)) ˆ 1.2, H C(2)); 6.22 (s, H C(9)); 3.71, 3.66 (2s, 2 MeOCO); 3.39, 3.17 (AB, JAB ˆ 13.7,
MeSCH2); 2.12 (t-like, J ˆ 1.0, Me C(1)); 2.00 (s, MeSCH2); 1.76 (s, Me C(10)); 1.19 (s, t-Bu). 13C-NMR
(300 MHz, CDCl3): 167.78, 167.44 (s, 2 MeOCO); 151.60 (s); 143.73 (s); 143.28 (s); 139.30 (d); 132.27 (s);
130.94 (s); 130.64 (s); 129.10 (s); 127.78 (d); 126.50 (d); 125.85 (d); 123.33 (s); 51.92, 51.73 (q, 2 MeOCO); 40.11
(t, MeSCH2); 36.26 (s, Me3C); 30.04 (q, Me3C); 24.21 (q, Me C(1)); 18.77 (q, Me C(10)); 15.60 (q, MeSCH2).
.
‡
‡
EI-MS: 415 (22), 414 (100, M ), 367 (58, [M MeS] ), 353 (73), 335 (73). Anal. calc. for C24H30O4S (414.57):
C 69.53, H 7.29; found: C 69.96, H 7.22.
1.5. {[8-(tert-Butyl)-4,5-bis(methoxycarbonyl)-1,10-dimethylheptalen-6-yl]methyl}dimethylsulfonium Te-
trafluoroborate (8). To the stirred soln. of 7 (32 mg, 0.077 mmol) in CH2Cl2 (2 ml), trimethyloxonium
tetrafluoroborate (17 mg, 0.116 mmol) was added at 258. After stirring overnight, the suspension was removed
by filtration. Recrystallization from CH2Cl2/Et2O gave pure 6 (32 mg, 80%). Yellow solid. M.p. 183.2 ± 184.18
(CH2Cl2/Et2O). UV/VIS (CH2Cl2/hexane): lmax 328 (sh, 3.4), 270 (4.08); lmin 257 (4.05). IR (KBr): 2953m,
1719s, 1642w, 1435m, 1392w, 1374w, 1259s, 1199m, 1155w, 1083s, 780w, 770w. 1H-NMR (300 MHz, CDCl3): 7.50
(d, J(2,3) ˆ 6.1, H C(3)); 6.82 (s, H C(7)); 6.35 (s, H C(9)); 6.32 (dd, J(2,3) ˆ 6.3, 4J(2, Me C(1)) ˆ 1.2,
‡
‡
H
C(2)); 4.33, 4.01 (AB, JAB ˆ 12.7, Me2S CH2); 3.69, 3.68 (2s, 2 MeOCO); 2.99, 2.87 (2s, Me2S CH2); 2.08
(s, Me C(1)); 1.78 (s, Me C(10)); 1.18 (s, t-Bu). 13C-NMR (75 MHz, CDCl3): 167.40, 167.99 (s, 2 MeOCO);
152.22 (s); 142.88 (s); 139.81 (d); 139.37 (s); 136.73 (d); 132.74 (s); 131.07 (s); 129.24 (d); 128.90 (s); 127.05 (d);
125.49 (s); 120.18 (s); 52.33, 52.12 (q, 2 MeOCO); 50.41 (t, Me2S CH2); 36.37 (s, Me3C); 29.83 (q, Me3C); 25.20
(q); 24.24 (q); 23.92 (q); 18.91 (q). FAB-MS: 429 (18, M , cation), 392 (24), 368 (99), 367 (100, [M Me2S] ),
307 (50).
‡
‡
‡
1.6. Dimethyl 8-(tert-Butyl)-6-(iodomethyl)-1,10-dimethylheptalene-4,5-dicarboxylate (9). Heptalene 7
(17 mg, 0.04 mmol) and MeI (80 mg, 0.56 mmol) in MeCN (0.36 ml) were heated at 608 for 24 h [17]. After
removal of the solvent, CC (silica gel; hexane/Et2O 1:) yielded 9 (16 mg, 82%). Yellow crystals. M.p. 151.0 ±
151.88 (hexane). Rf (hexane/Et2O 1 :1) 0.40. UV/VIS (hexane): lmax 320 (sh, 3.60), 276 (sh, 4.15), 249 (4.29); lmin
236 (4.28). IR (KBr): 2951m, 1712s, 1434m, 1303m, 1285m, 1261s, 1218w, 1197w, 1156m, 1010w, 1053m, 778w,
1
4
767w. H-NMR (300 MHz, CDCl3): 7.57 (d, J(2,3) ˆ 6.2, H C(3)); 6.58 (s, H C(7)); 6.33 (dd, J(2,3) ˆ 6.2, J

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Helvetica Chimica Acta ± Vol. 82 (1999)
(2, Me C(1)) ˆ 1.3, H C(2)); 6.28 (s, H C(9)); 4.31, 3.92 (AB, JAB ˆ 12.7, CH2I); 3.71, 3.68 (2s, 2 MeOCO);
2.28 (s, Me C(1)); 1.78 (s, Me C(10)); 1.19 (s, t-Bu). 13C-NMR (75 MHz, CDCl3): 167.70, 167.30 (s, 2 MeO-
CO); 151.29 (s); 144.11 (s); 141.24 (s); 139.84 (d); 134.25 (s); 131.11 (s); 131.06 (d); 131.01 (s); 129.60 (s); 128.09
(d); 126.88 (d); 124.50 (s); 51.97, 51.88 (q, 2 MeOCO); 36.30 (s, Me3C); 29.96 (q, Me3C); 24.39 (q, Me C(1));
‡
‡
19.16 (q, Me C(10)); 7.76 (t, CH2I). CI-MS: 512 (35, [M ‡ NH4] ), 495 (22, [M ‡ 1] ), 463 (100).
1.7. Dimethyl 8-(tert-Butyl)-6-formyl-1,10-dimethylheptalene-4,5-dicarboxylate (12). To compound
7
(83 mg, 0.2 mmol) in CCl4 (10 ml) at 258, N-chlorosuccinimide (30 mg, 0.22 mmol) was added in portions.
After the suspension had been stirred at 258 for 2 h, the resulting succinimide was removed by filtration. The
filtrate was concentrated under reduced pressure and then dissolved in THF (1 ml). This yellow soln. was added
to the suspension of HgO (44 mg, 0.2 mmol) and BF3 ´ OEt2 (28 mg, 0.2 mmol) in H2O/THF 4 : 1 (4 ml). The
mixture was stirred for 1 h at 258. Et2O and aq. Na2CO3 were added subsequently. After filtration and extraction
with Et2O, the solvent was removed under reduced pressure to give a yellow residue, which was recrystallized
from CH2Cl2/hexane to yield 12 in nearly quantitative yield (76 mg, 99%). Yellow crystals. M.p. 208.9 ± 209.78
(CH2Cl2/hexane). Rf (hexane/Et2O 1 : 1) 0.25. UV/VIS (hexane): lmax 310 (sh, 3.75), 266 (4.33); lmin 256 (4.32).
IR (KBr): 2949w, 1724s, 1702s, 1675m, 1640w, 1437w, 1375w, 1299w, 1273m, 1255s, 1190w, 1156w, 1089w, 1055w,
782w. 1H-NMR (300 MHz, CDCl3): 9.53 (s, CHO); 7.56 (dd, J(2,3) ˆ 5.9, 5J(3, Me C(1)) ˆ 0.9, H C(3)); 7.23
4
(d, J ˆ 1.0, H C(7)); 6.56 (s, H C(9)); 6.33 (dd, J(2,3) ˆ 5.9, J(2, Me C(1)) ˆ 1.4, H C(2)); 3.71, 3.51 (2s,
2 MeOCO); 1.95 (d, 4J(2,Me C(1)) ˆ 1.1, Me C(1)); 1.81 (s, Me C(10)); 1.28 (s, t-Bu). 13C-NMR (75 MHz):
189.92 (d, CHO); 167.24, 166.94 (2s, MeOCO); 151.11 (s); 144.69 (d); 141.72 (s); 139.39 (d); 135.13 (s); 133.97
(s); 132.13 (d); 131.94 (s); 131.80 (s); 131.15 (s); 126.63 (d); 125.29 (s); 51.97, 51.77 (2q, MeOCO); 36.40
‡
(s, Me3C); 30.09 (q, Me3C); 23.68 (q); 19.00 (q). CI-MS: 400 (36, [M ‡ NH4] ), 368 (62), 351 (100). Anal. calc.
for C23H26O5 (382.46): C 72.23, H 6.85; found: C 72.58, H 7.17. The structure of 12 was confirmed by an X-ray
crystals-structure analysis (cf. Fig. 1).
1.8. Dimethyl 8-(tert-Butyl)-1,10-dimethyl-6-[(E)-2-phenylethenyl]heptalene-4,5-dicarboxylate (2a). To 12
(7.7 mg, 0.02 mmol) in the two-phase system of CH2Cl2/2n NaOH (1:1; 2 ml), a soln. of (benzyl)triphenyl-
phosphonium chloride (13a; 46.7 mg, 0.12 mmol) in CH2Cl2 (1 ml) was added at 258. After 2 h, the org. phase
was separated, and the solvent was removed. CC (silica gel; hexane/Et2O 1:1) yielded starting material 12 (2 mg,
26%) and a mixture of (E)-2a and (Z)-2a, which was isomerized with a catalytic amount of I2 in hexane/Et2O
soln. at 258 overnight to afford pure (E)-2a (6 mg, 66%). Yellow crystals. M.p. 174.1 ± 175.08. Rf (hexane/Et2O
1:1) 0.50. UV/VIS (hexane): lmax 334 (sh, 4.20), 295 (4.38), 260 (4.43); lmin 279 (4.34). IR (KBr): 2950m, 1721s,
1598w, 1559w, 1435m, 1390w, 1256s, 1196w, 1167w, 1088w, 1056w, 961w, 770w, 751w, 692w. 1H-NMR (300 MHz,
CDCl3): 7.68 (dd, J ˆ 0.9, J(2,3) ˆ 6.1, H C(3)); 7.40 (m, 2 arom. H); 7.32 (m, 2 arom. H); 7.26 (m, 1 ar-
om. H); 6.92 (d, J ˆ 15.8, CHˆCH C(6)); 6.59 (s, H C(7)); 6.47 (d, J ˆ 15.8, CHˆCH C(6)); 6.46
(dd, J(2,3) ˆ 6.1, 4J(2, Me C(1)) ˆ 1.4,
H C(2)); 6.33 (s, H C(9)); 3.78, 3.55 (s, 2 MeOCO); 2.04
(s, Me C(1)); 1.84 (s, Me C(10)); 1.28 (s, t-Bu). 13C-NMR (150 MHz, CDCl3): 167.92, 167.64 (s, 2 MeOCO);
153.00 (s); 143.06 (s); 139.52 (d, C(3)); 138.49 (s); 137.52 (s); 133.51 (s); 131.26 (s); 131.11 (s); 129.48 (d, C(7));
129.31 (s); 128.72 (d, 2 arom. C); 128.72 (d, CHˆCH C(6)); 128.44 (d, CHˆCH C(6)); 127.67 (d, 1 ar-
om. C); 127.15 (d, C(9)); 126.76 (d, 2 arom. C); 126.36 (d, C(2)); 125.06 (s); 52.28, 52.00 (q, 2 MeOCO); 36.76
.
‡
(s, Me3C); 30.59 (q, Me3C); 23.35 (q, Me C(1)); 18.94 (q, Me C(10)). EI-MS: 457 (14), 456 (47, M ), 441 (9,
‡
‡
[M Me] ), 424 (14), 397 (100, [M MeOCO] ), 365 (43).
1.9. Dimethyl 8-(tert-Butyl)-1,10-dimethyl-6-[(E)-2-(4-methoxyphenyl)ethenyl]heptalene-4,5-dicarboxylate
(2b). At 08, a 1m t-BuOK soln. (0.03 ml, 0.03 mmol) was added to the suspension of (4-methoxyphenyl)-
triphenylphosponium chloride (13b; 16.8 mg, 0.04 mmol) in THF (0.5 ml). After the temp. had been raised to
258, 12 (7.7 mg, 0.02 mmol) was added to this soln. The reaction was stopped by addition of H2O after 30 min.
Extraction with Et2O and CC (silica gel; hexane/Et2O 1 :1) provided pure (E)-2b (3 mg, 31%). Yellow crystals.
M.p. 182.0 ± 182.88. Rf (hexane/Et2O 1:1) 0.37. UV/VIS (hexane): lmax 334 (sh, 4.25), 302 (4.36), 262 (4.39); lmin
282 (4.31). IR (KBr): 2961m, 1723s, 1605w, 1510m, 1435w, 1389w, 1254s, 1197w, 1173m, 1087w, 1032w, 954w,
843w, 769w. 1H-NMR (300 MHz, CDCl3): 7.66 (dd, J(2,3) ˆ 6.1, 5J(3, Me C(1)) ˆ 0.9, H C(3)); 7.31 (d, J ˆ
8.8, 2 arom. H); 6.85 (d, J ˆ 8.8, 2 arom. H); 6.78 (d, J ˆ 16.0, CHˆCH C(6)); 6.53 (s, H C(7)); 6.45
(dd, J(2,3) ˆ 6.1, 4J(2, Me C(1)) ˆ 1.4, H C(2)); 6.40 (d, J ˆ 16.0, CHˆCH C(6)); 6.29 (s, H C(9)); 3.83,
3.76 (s, 2 MeOCO); 3.53 (s, MeOC6H4); 2.01 (s, Me C(1)); 1.82 (s, Me C(10)); 1.28 (s, t-Bu). EI-MS: 487
.
‡
(12), 486 (38, M ), 428 (32), 427 (100).
1.10. Dimethyl 8-(tert-Butyl)-6-[(E)-2-(4-chlorophenyl)ethenyl]-1,10-dimethylheptalene-4,5-dicarboxylate
(2c). The Wittig reaction of 12 (19.1 mg, 0.05 mmol) and (4-chlorophenyl)triphenylphosphonium chloride (13c;
127 mg, 0.3 mmol) in the two-phase system CH2Cl2/2n NaOH (1:1, 5 ml) was carried out as described for 2a to
give the mixture of (E)-2c and (Z)-2c, which was isomerized in the presence of a catalytic amount of I2 in boiling

Helvetica Chimica Acta ± Vol. 82 (1999)
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toluene overnight to pure (E)-2c (20 mg, 82%). Yellow crystals. M.p. 178.0 ± 179.08 (hexane). Rf (hexane/Et2O
1:1) 0.52. UV/VIS (hexane): lmax 332 (sh, 4.20), 296 (4.39), 262 (4.39); lmin 279 (4.34). IR (KBr): 2951m, 1728s,
1559w, 1490w, 1435m, 1391w, 1255s, 1196w, 1168w, 1090m, 1056w, 1011w, 964w, 846w, 812w, 780w. 1H-NMR
(300 MHz, CDCl3): 7.67 (dd, J(2,3) ˆ 6.0, 5J(3, Me C(1) ˆ 1.0, H C(3)); 7.30 (d-like, J ˆ 9.1, 2 arom. H); 7.29
(d-like, J ˆ 9.1, 2 arom. H); 6.87 (dd, J ˆ 16.0, CHˆCH C(6)); 6.58 (s, H C(7)); 6.45 (dd, J(2,3) ˆ 6.1,
4J(2, Me C(1)) ˆ 1.4, H C(2)); 6.40 (d, J ˆ 16.0, CHˆCH C(6)); 6.33 (s, H C(9)); 3.76, 3.53 (s, 2 MeO-
CO); 2.02 (t, J ˆ 1.1, Me C(1)); 1.83 (s, Me C(10)); 1.28 (s, t-Bu). 13C-NMR (75 MHz, CDCl3): 167.62, 167.25
(s, 2 MeOCO); 152.66 (s); 142.73 (s); 139.28 (d); 137.93 (s); 135.71 (s); 132.98 (s); 132.92 (s); 130.95 (s); 129.73
(d); 129.00 (s); 128.76 (d); 128.61 (d, 2arom. C); 127.57 (d, 2 arom. C); 127.11 (d); 127.01 (d); 126.13 (d); 124.88
1
(s); 51.97, 51.67 (q, 2 MeOCO); 36.42 (s, Me3C); 30.23 (q, Me3C); 23.01 (q, Me C(1)); 18.61 (q, Me C(10)) ).
‡
‡
CI-MS: 510, 508 (8/22, [M ‡ NH4] ), 493, 491 (12/29, [M ‡ 1] ), 461 (37), 459 (100).
1.11. Dimethyl 8-(tert-Butyl)-1,10-dimethyl-6-[(E)-2-(4-nitrophenyl)ethenyl]heptalene-4,5-dicarboxylate
(2d). To 12 (7.7 mg, 0.02 mmol) in the two-phase system CH2Cl2/2n NaOH (1:1; 2 ml), a soln. of (4-
nitrobenzyl)triphenylphosphonium bromide (13d; 57.4 mg, 0.12 mmol) in CH2Cl2 (1 ml) was added at 258 under
stirring. After 4 h, additional 13d (57.4 mg, 0.12 mmol) was introduced. After another 4 h, the org. phase was
separated. CC (silica gel, hexane/Et2O 1:1) afforded starting material 12 (2 mg, 26%) and the mixture of (E)-2d
and (Z)-2d. The isomerization in the presence of a catalytic amount of I2 in boiling toluene overnight afforded
pure (E)-2d (1.5 mg, 15%). Yellow crystals. M.p. 184.1 ± 185.48 (hexane). Rf (hexane/Et2O 1:1) 0.43. UV/VIS
(hexane): lmax 358 (4.30), 260 (sh, 4.25), 242 (4.48); lmin 313 (4.22). 1H-NMR (300 MHz, CDCl3): 8.13 (d, J ˆ 8.8,
2 arom. H); 7.65 (d, J(2,3) ˆ 5.9, H C(3)); 7.45 (d, J ˆ 8.8, 2 arom. H); 7.02 (d, J ˆ 15.8, CHˆCH C(6)); 6.65
(s, H C(7)); 6.44 (d, J(2,3) ˆ 5.9, H C(2)); 6.43 (d, J ˆ 15.8, CHˆCH C(6)); 6.34 (s, H C(9)); 3.73, 3.49
‡
(s, 2 MeOCO); 2.00 (s, Me C(1)); 1.80 (s, Me C(10)); 1.25 (s, t-Bu). CI-MS: 520 (16), 519 (58, [M ‡ NH4] ),
.
‡
502 (16), 501 (7, M ), 487 (10), 471 (31), 470 (100).
1.12. Dimethyl 8-(tert-Butyl)-1,10-dimethyl-6-[(E,E)-4-phenylbuta-1,3-dienyl]heptalene-4,5-dicarboxylate
(2e). Method I: The Wittig reaction of 12 (7.7 mg, 0.02 mmol) and [(E)-3-phenylprop-2-enyl]triphenylphos-
phonium bromide (13e; 55 mg, 0.12 mmol) in the two phase system CH2Cl2/2n NaOH (1:1, 2 ml) was performed
as described for 2a to yield pure 2e (8.3 mg, 86%).
Method II: At 788, to a stirred soln. of LDA (0.15 mmol; prepared from BuLi soln. (0.1 mmol,
0.15 mmol) and (i-Pr)2NH (0.03 ml, 0.2 mmol)) in THF (1 ml), diethyl [(E)-3-phenylprop-2-enyl] phosphonate
(0.046 ml, 0.2 mmol) was added. After stirring for 20 min at 788, the color of the mixture became pale yellow,
and 12 (38.2 mg, 0.1 mmol) was added. The temp. was raised to 258 in 4 h, and the reaction was quenched by
addition of H2O. Extraction by Et2O, followed by CC (silica gel; hexane/Et2O 1 : 1) yielded 2e (42 mg, 87%).
Method III: At 08, to the suspension of CrCl2 (344 mg, 2.8 mmol) in THF (4 ml), a soln. of CHI3 (315 mg,
0.8 mmol) in THF (1 ml) and 12 (76 mg, 0.2 mmol) in THF (3 ml) was added. The mixture was warmed to 258,
and stirring continued for 1 h before the reaction was quenched by addition of H2O. After extraction with Et2O,
the org. phase was washed with H2O and dried (anh. Na2SO4). Removal of Et2O left a yellow residue, which was
dissolved in DMF (0.5 ml). To this soln., Pd(OAc)2 (4.5 mg, 0.02 mmol), Ag2CO3 (55.2 mg, 0.2 mmol), and
styrene (62.5 mg, 0.6 mmol) were added at 258. After stirring overnight, H2O was added to stop the reaction.
Extraction by Et2O and chromatography on silica gel (hexane/CH2Cl2/Et2O 8 :1:1) gave heptalene 2e (56 mg,
59%).
Data of 2e: Yellow crystals. M.p. 181.2 ± 183.18 (hexane). Rf (hexane/Et2O 1:1) 0.43. UV/VIS (hexane):
lmax 380 (sh, 4.15), 346 (4.49), 322 (84.50), 262 (4.39), 242 (4.42); lmin 334 (4.48), 279 (4.33), 257 (4.38), 228
(4.40). IR (KBr): 3019w, 2954m, 1726s, 1560w, 1437m, 1388w, 1256s, 1194w, 1168w, 1093m, 1056w, 986m, 831w,
2
783w, 768w, 756w, 690w. 1H-NMR (300 MHz, CDCl3) ): 7.62 (d, J(2,3) ˆ 6.1, H C(3)); 7.35 (m, 2 arom. H);
7.27 (m, 2 arom. H); 7.19 (m, 1 arom. H); 6.76 (dd, J(3',4') ˆ 15.5, J(2',3') ˆ 10.6, H C(3')); 6.49 (d, J(3',4') ˆ
15.6, H C(4')); 6.46 (s, H C(7)); 6.43 (d, J(1',2') ˆ 15.6, H C(1'); 6.41 (d, J(2,3) ˆ 6.2, H C(2)); 6.25
(s, H C(9)); 6.24 (dd, J(2',3') ˆ 10.6, J(1',2') ˆ 15.5, H C(2')); 3.65, 3.94 (2s, 2 MeOCO); 1.92 (s, Me C(1));
1.71 (s, Me C(10)); 1.16 (s, t-Bu). 13C-NMR (75 MHz, CDCl3): 167.62, 167.32 (2s, MeOCO); 152.72 (s); 142.74
(s); 139.21 (d); 138.24 (s); 137.26 (s); 133.41 (s); 133.06 (d); 132.05 (d); 130.94 (s); 130.84 (s); 129.26 (d); 129.06
(d); 128.93 (s); 128.83 (d); 128.52 (d, 2 arom. C); 127.40 (d); 126.90 (d); 126.18 (d, 2 arom. C); 126.05 (d);
124.66 (s); 51.95, 51.70 (2q, MeOCO); 36.42 (s, Me3C); 30.26 (q, Me3C); 23.09 (q); 18.59 (q). CI-MS: 500 (41,
1
)
)
The signals for two quaternary C-atoms coincided.
The C-atoms of the butadienyl side-chain are indicated by primed numbers.
2

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Helvetica Chimica Acta ± Vol. 82 (1999)
‡
‡
[M ‡ NH4] ), 483 (100, [M ‡ 1] ), 451 (63). Anal. calc. for C32H32O4 (482.62): C 79.64, H 7.10; found: C 79.18,
H 7.26.
1.13. 4-[Bis(methylthio)methyl]-6,8-dimethylazulene (16) [7]. To a stirred soln. of 15 (1.7 g, 10 mmol) in
Et2O (70 ml) at 788, 0.6m of NaN(SiMe3)2 in toluene (34.2 ml, 20.5 mmol) was added over 10 min. The temp.
was raised to 258, and then MeSSMe (1.88 g, 20 mmol) was added. The reaction was quenched with H2O after
stirring at 258 for 2 h. Extraction with hexane, followed by CC (silica gel; hexane/Et2O 98 : 2) afforded
disubstituted azulene 16 (1.6 g, 61%). Blue crystals. M.p. 79.2 ± 80.68 (hexane) ([7]: 80 ± 818). 1H-NMR
(300 MHz, CDCl3): 7.88 (t, J(1,2) ꢀ J(1,3) ꢀ 3.9, H C(2)); 7.77 (s, H C(5)); 7.65 (d, J(1,2) ˆ 3.9, H C(1));
7.62 (d, J(2,3) ˆ 3.6, H C(3)); 7.29 (s, H C(7)); 5.92 (s, (MeS)2CH); 3.06 (s, Me C(8)); 2.87 (s, Me C(6));
2.35 (s, (MeS)2CH).
1.14. 4-[Bis(methylthio)methyl]-6,8-dimethylazulene-1-carbaldehyde (17a) and 4-[Bis(methylthio)methyl]-
6,8-dimethylazulene-3-carbaldehyde (17b). The Vilsmeier formylation of 16 (1.7 g, 6.48 mmol) was performed
according to [5] to yield, after CC (silica gel; hexane/Et2O/CH2Cl2 80 :5 :15), 17b (0.52 g, 27.6%) in the first
fraction and 17a (1.26 g, 67%) in the second.
Data of 17a: Violet crystals. M.p. 129.0 ± 129.58 (Et2O). Rf (hexane/Et2O 1:1) 0.23. UV/VIS (hexane): lmax
529 (2.81), 390 (3.92), 316 (4.55), 249 (4.35); lmin 429 (1.75), 351 (3.77), 270 (3.86). IR (KBr): 2981w, 2908w,
1626s, 1581m, 1551w, 1497m, 1430m, 1352s, 1326m, 1304m, 1246w, 1207w, 1076w, 962w, 907w, 854w, 721w, 694w.
1H-NMR (600 MHz, CDCl3): 10.68 (s, CHO); 8.31 (d, J(2,3) ˆ 4.7,
H C(2)); 7.89 (s, H C(5)); 7.46
(s, H C(7)); 7.45 (d, J(2,3) ˆ 4.7, H C(3)); 5.69 (s, (MeS)2CH); 3.19 (s, Me C(8)); 2.74 (s, Me C(6));
2.18 (s, (MeS)2CH). 1H-NOE (600 MHz, CDCl3): CHO ! H C(2), Me C(8), (MeS)2CH ! H C(7),
H
C(3), (MeS)2CH. 13C-NMR (75 MHz, CDCl3): 186.98 (d, CHO); 148.60 (s); 148.43 (s); 147.90 (s); 141.22
(s); 138.01 (s); 137.95 (d); 134.40 (d); 131.69 (s); 128.73 (d); 115.20 (d); 56.18 (d, (MeS)2CH); 31.09
.
‡
(q, Me C(8)); 28.46 (q, Me C(6)); 16.15 (q, (MeS)2CH). EI-MS: 290 (53, M ), 275 (10), 262 (24), 243
(100). Anal. calc. for C16H18OS2 (290.45): C 66.17, H 6.25, S 22.08; found: C 66.06, H 6.25, S 22.30.
Data of 17b: Violet crystals. M.p. 93.9 ± 97.78 (Et2O). Rf (hexane/Et2O 1:1) 0.43. UV/VIS (hexane): lmax 512
(3.03), 394 (3.03), 316 (4.51), 248 (4.37); lmin 429 (2.34), 354 (3.77), 275 (3.86), 236 (4.26). IR (KBr): 2998w,
2918w, 1652s, 1628s, 1588m, 1549w, 1494w, 1434w, 1415m, 1385m, 1358w, 1329s, 1302m, 1211w, 1188w, 1096w,
1057w, 794w, 781m, 725w. 1H-NMR (600 MHz, CDCl3): 10.20 (s, CHO); 8.18 (d, J(1,2) ˆ 4.4, H C(2)); 7.98
(s, H C(5)); 7.41 (s, H C(7)); 7.36 (d, J(1,2) ˆ 4.3, H C(1)); 7.15 (s, (MeS)2CH); 2.90 (s, Me C(8)); 2.73
(s, Me C(6)); 2.17 (s, (MeS)2CH). 1H-NOE (600 MHz, CDCl3): CHO ! H C(2), (MeS)2CH);
(MeS)2CH ! CHO, H C(5), (MeS)2CH. 13C-NMR (75 MHz, CDCl3): 186.61 (d, CHO); 152.13 (s); 149.35
(s); 147.68 (s); 145.83 (d); 145.32 (s); 134.59 (s); 133.60 (d); 129.97 (d); 127.67 (s); 117.72 (d); 57.26
.
‡
(d, (MeS)2CH); 28.33 (q, Me C(8)); 26.27 (q, Me C(6)); 15.77 (q, (MeS)2CH). EI-MS: 290 (25, M ), 243
(72), 199 (27), 196 (100). Anal. calc. for C16H18OS2 (290.45): C 66.17, H 6.25, S 22.08; found: C 65.99, H 6.16,
S 22.19.
1.15. 4-[Bis(methylthio)methyl]-1,6,8-trimethylazulene (18). The reduction of 17a (1.21 g, 4.17 mmol) with
NaBH4 (4.73 g, 125 mmol) in CF3COOH/CH2Cl2 (1:1, 130 ml) at 258 for 9 h was accomplished as described in
[5] to yield the mixture (940 mg) of 18 (723 mg, 63%) and the further reduced product 19 (217 mg, 23%). The
fractional crystallization of this mixture from hexane led to pure 18 (600 mg, 52%). Blue crystals. M.p. 80.7 ±
81.98 (hexane). Rf (hexane/Et2O 95 :5) 0.37. UV/VIS (hexane): lmax 585 (2.81), 359 (3.65), 291 (4.63), 246
(4.36); lmin 400 (0.4), 332 (3.42), 264 (3.98), 222 (4.11). IR (KBr): 2974w, 2912m, 1576s, 1516m, 1433s, 1394w,
1378m, 1334w, 1320w, 1297w, 1258w, 1176w, 1148w, 1072m, 1029w, 950m, 843w, 791s, 708m. 1H-NMR (300 MHz,
CDCl3): 7.44 (d, J(2,3) ˆ 4.2, H C(2)); 7.35 (s, H C(5)); 7.34 (d, J(2,3) ˆ 4.2, H C(3)); 6.87 (s, H C(7));
5.66 (s, (MeS)2CH); 3.00 (s, Me C(8)); 2.86 (s, Me C(6)); 2.57 (s, Me C(1)); 2.14 (s, (MeS)2CH). 13C-NMR
(75 MHz, CDCl3): 147.07 (s); 146.37 (s); 145.54 (s); 137.61 (d); 136.50 (s); 133.66 (s); 128.72 (d); 128.19 (s);
121.97 (d); 112.57 (d); 55.82 (d, Me2SCH); 28.42 (q); 27.83 (q); 19.71 (q); 16.22 (q, Me2SCH). EI-MS: 277 (14),
.
‡
276 (89, M ), 229 (100).
Data of 1,6,8-Trimethyl-4-[(methylthio)methyl]azulene (19). Rf (hexane/Et2O 95 :5) 0.39. 1H-NMR
(300 MHz, CDCl3; taken from the data of the mixture with 18): 7.51 (d, J(2,3) ˆ 4.1, H C(2)); 7.35
(d, J(2,3) ˆ 4.1, H C(3)); 7.01 (s, H C(5)); 6.91 (s, H C(7)); 4.20 (s, MeSCH2 C(4)); 3.06 (s, Me C(8));
.
‡
2.93 (s, Me C(6)); 2.62 (s, Me C(1)); 2.03 (s, MeSCH2 C(4)). EI-MS (GC/MS): 231 (26), 230 (100, M ),
215 (58), 200 (64), 184 (92).
1.16. Dimethyl 1,8,10-Trimethyl-6-[bis(methylthio)methyl]heptalene-4,5-dicarboxylate (20a). The thermal
reaction of 18 (329 mg, 1.19 mmol) and ADM (0.44 ml, 3.57 mmol) in toluene (12 ml) was performed as
described for 7 to yield 20a (150 mg, 30%) as yellow crystals and its DBS isomer 20b (25 mg, 5%) as yellow oil.

Helvetica Chimica Acta ± Vol. 82 (1999)
1703
Data of 20a: M.p. 92.1 ± 92.78 (hexane). Rf (hexane/Et2O 1 :1) 0.36. UV/VIS (hexane): lmax 308 (sh, 3.70),
270 (4.14); lmin 252 (4.11). IR (KBr): 2948w, 2917w, 1722s, 1572w, 1436m, 1298m, 1268s, 1244s, 1195w, 1170w,
1144w, 1099w, 1083m, 1048w, 777w, 736w. 1H-NMR (600 MHz, CDCl3): 7.54 (dd, J(2,3) ˆ 6.1, 5J(3, Me C(1)) ˆ
0.8, H C(3)); 6.27 (dd, J(2,3) ˆ 6.1, 4J(2, Me C(1)) ˆ 1.1, H C(2)); 6.25 (s, H C(7)); 6.16 (s, H C(9)); 4.26
(d, J ˆ 0.7, Me2SCH); 3.71 (s, 2 MeOCO); 2.16, 1.90 (2s, Me2SCH); 2.10 (t-like, Me C(1)); 2.09
(d, 4J(9, Me C(8)) ˆ 1.1, Me C(8)); 1.73 (s, Me C(10)). 13C-NMR (75 MHz, CDCl3): 167.66, 167.35
(2s, MeOCO); 144.61 (s); 142.73 (s); 139.90 (d); 138.05 (s); 131.66 (d); 130.96 (s); 130.93 (s); 130.89 (s);
129.39 (d); 127.99 (s); 126.19 (d); 124.55 (s); 56.05 (d, Me2SCH); 52.04, 51.96 (2q, MeOCO); 25.25 (q); 24.11
.
‡
(q); 18.61 (q); 15.58 (q); 11.37 (q). EI-MS: 418 (13, M ), 371 (100).
Data of Dimethyl 10-[Bis(methylthio)methyl]-5,6,8-trimethylheptalene-1,2-dicarboxylate (20b): Rf (hexane/
Et2O) 0.48. 1H-NMR (300 MHz, CDCl3): 6.86, 6.81 (AB, JAB ˆ 11.8, H C(3,4)); 6.79 (s, H C(9)); 6.29
(s, H C(7)); 4.87 (s, (MeS)2CH); 4.03, 3.96 (s, 2 MeOCO); 2.38, 2.04 (2s, (MeS)2CH); 2.25 (m, Me C(6,8));
.
‡
‡
2.00 (s, Me C(5)). EI-MS: 418 (6, M ), 371 (100, [M MeS] ).
1.17. Dimethyl 6-Formyl-1,8,10-trimethylheptalene-4,5-dicarboxylate (21). To a suspension of HgO (76.6 mg,
0.354 mmol) and BF3 ´ OEt2 (48 mg, 0.354 mmol) in H2O/THF (4 : 1; 4 ml), a soln. of 20a (74 mg, 0.177 mmol)
in THF was added at 258. After stirring for 1 h, Et2O and aq. Na2CO3 soln. was added. Extraction with Et2O and
chromatographic workup (silica gel; hexane/Et2O 1 : 1) afforded 21 (53 mg, 88%). Yellow crystals. M.p. 207.5 ±
208.38. Rf (hexane/Et2O 1 : 1) 0.18. UV/VIS (hexane/CH2Cl2): lmax 360 (sh, 3.20), 320 (sh, 3.60), 267 (4.25); lmin
255 (4.24). IR (KBr): 2949w, 1721s, 1678m, 1567w, 1435w, 1298w, 1270s, 1251m, 1199w, 1159w, 1089w, 1055w,
836w, 771w. 1H-NMR (300 MHz, CDCl3): 9.51 (s, CHO); 7.57 (dd, J(2,3) ˆ 5.9, 5J(3, Me C(1)) ˆ 1.0,
H
H
C(3)); 6.93 (d, J ˆ 0.7,
H
C(7)); 6.53 (s, H C(9)); 6.34 (dd, J(2,3) ˆ 5.9, 4J(2 Me C(1)) ˆ 1.4,
C(2)); 3.72, 3.60 (s, 2 MeOCO); 2.22 (d, 4J(9, Me C(8)) ˆ 1.2, Me C(8)); 1.97 (t, 4J(2, Me C(1)) ꢀ
5J(3, Me C(1)) ꢀ 1.2, Me C(1)); 1.81 (s, Me C(10)). 13C-NMR (75 MHz, CDCl3): 190.13 (d, CHO);
167.24, 167.01 (s, 2 MeOCO); 146.35 (d); 142.04 (s); 139.73 (d); 137.84 (s); 137.51 (d); 135.47 (s); 132.28 (s);
132.23 (s); 131.26 (s); 130.57 (s); 126.85 (d); 125.37 (s); 52.00, 51.85 (q, 2 MeOCO); 24.31 (q); 23.67 (q); 18.80
‡
‡
(q). CI-MS: 358 (21, [M ‡ NH4] ), 341 (3, [M ‡ 1] ), 326 (50), 310 (21), 309 (100).
1.18. Dimethyl 1,8,10-Trimethyl-6-[(E,E)-4-phenylbuta-1,3-dienyl]heptalene-4,5-dicarboxylate (22). The
Wittig reaction of 21 (51 mg, 0.15 mmol) and [(E)-3-phenylprop-2-enyl]triphenylphosphonium bromide (13e;
413 mg, 0.90 mmol) in the two-phase system CH2Cl2/2n NaOH was carried out as described for 2a to yield 22
(62 mg, 94%). Yellow crystals. M.p. 218.2 ± 218.88 (hexane). Rf (hexane/Et2O 1 :1): 0.38. UV/VIS (hexane): lmax
347 (4.40), 323 (4.43), 265 (4.29); lmin 337 (4.39), 283 (4.26), 257 (4.28). IR (KBr): 2945w, 1722s, 1563w, 1432m,
2
1254s, 1193w, 1158w, 1090m, 1055w, 995w, 788w, 771w, 750w, 691w. 1H-NMR (300 MHz, CDCl3) ): 7.63
(dd, J(2,3) ˆ 6.0, 5J(3, Me C(1)) ˆ 1.0, H C(3)); 7.35 (m, 2 arom. H); 7.27 (m, 2 arom. H); 7.20 (m, 1 ar-
om. H); 6.78 (dd, J(3',4') ˆ 15.5, J(2',3') ˆ 10.1, H C(3')); 6.49 (d, J(3',4') ˆ 15.5, H C(4')); 6.40 (dd, J(2,3) ˆ
4
6.0, J(2, Me C(1)) ˆ 1.4, H C(2)); 6.39 (d, J(1',2') ˆ 15.2, H C(1')); 6.29 (dd, J(1',2') ˆ 15.2, J(2',3') ˆ 10.1,
H
C(2')); 6.19 (s, H C(7)); 6.18 (d, 4J(9, Me C(1)) ˆ 1.2,
H C(9)); 3.70, 3.54 (s, 2 MeOCO); 2.10
(d, 4J(9, Me C(1)) ˆ 1.0, Me C(8)); 1.96 (t, 4J(2, Me C(1)) ꢀ J(3, Me C(1)) ꢀ 1.1, Me C(1)); 1.74
(s, Me C(10)). 13C-NMR (75 MHz, CDCl3): 167.53, 167.32 (s, 2 MeOOC); 143.10 (s); 139.62 (d); 139.38 (s);
138.46 (s); 137.19 (s); 133.37 (d); 132.05 (s); 132.01 (d); 131.89 (d); 131.45 (d); 131.11 (s); 131.02 (s); 129.62 (d);
128.77 (d); 128.55 (d, 2 arom. C); 127.51 (d); 127.07 (s); 126.34 (d, 2 arom. C); 126.24 (d); 124.87 (s); 52.00,
5
.
‡
51.82 (q, 2 MeOOC); 25.06 (q); 23.09 (q); 18.38 (q). EI-MS: 441 (29), 440 (100, M ), 408 (10), 381 (72), 349
(51).
1.19. 4-[Bis(methylthio)methyl]-7-methylazulene (24). To a stirred soln. of 4,7-dimethylazulene (23; 2.22 g,
14.22 mmol) in Et2O (95 ml) at 788, a 0.6m soln. of NaN(SiMe3)2 in toluene (47.2 ml, 28.44 mmol) was added
over 10 min. The temp. was raised slowly to 258, and MeSSMe (2.68 g, 28.44 mmol) was added. The reaction was
quenched with H2O after stirring at 258 for 2 h. Extraction with hexane, followed by CC (silica gel; hexane/
Et2O) afforded starting 23 (0.36 g, 16%) and 24 (1.54 g, 44%). Blue crystals. M.p. 69.7 ± 70.58 (hexane). Rf
(hexane/Et2O 95 : 5) 0.38. UV/VIS (hexane): lmax 591 (2.68), 363 (3.38), 283 (4.54), 242 (4.30); lmin 435 (0.20),
359 (3.20), 260 (4.08). IR (KBr): 2984w, 2916w, 1552m, 1522w, 1484w, 1458w, 1433m, 1415m, 1365s, 1288w,
1
1265w, 1191w, 1172w, 1136w, 1014w, 964w, 948m, 910w, 832w, 798m, 774s, 728w. H-NMR (300 MHz, CDCl3):
8.34 (s, H C(8)); 7.89 (t, J(1,2) ꢀ J(2,3) ꢀ 3.9, H C(2)); 7.63 (m, H C(5,6)); 7.48 (d, J(1,2) ˆ 3.8, H C(1));
7.37 (d, J(2,3) ˆ 3.8, H C(3)); 5.74 (s, (MeS)2CH); 2.68 (s, Me C(7)); 2.22 (s, (MeS)2CH). 13C-NMR
(75 MHz, CDCl3): 145.13 (s); 140.68 (s); 138.64 (d); 137.74 (d); 136.46 (s); 136.26 (d); 131.99 (s); 122.01 (d);
118.68 (d); 112.67 (d); 55.35 (d, (MeS)2CH); 25.99 (q, Me C(7)); 16.08 (q, (MeS)2CH). CI-MS: 249 (100,
.
‡
‡
[M ‡ 1] ), 248 (24, M ), 201 (53). Anal. calc. for C14H16S2 (248.41): C 67.69, H 6.49; found: C 67.72, H 6.63.

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Helvetica Chimica Acta ± Vol. 82 (1999)
1.20. Dimethyl 6-[Bis(methylthio)methyl]-9-methylheptalene-4,5-dicarboxylate (25) and Dimethyl 10-
[Bis(methylthio)methyl]-7-methylheptalene-4,5-dicarboxylate (26a). The azulene 24 (1.54 g, 6.2 mmol) and
ADM (2.64 g, 18.6 mmol) in toluene (55 ml) were heated at 1308 for 30 h. After removal of the solvent, CC
(silica gel; hexane/Et2O/CH2Cl2 80 :5 :15) yielded 25 (0.547 g, 22.6%) and 26a/26b (0.088 g, 3.6%).
Data of 25: Yellow crystals. M.p. 102.7 ± 103.58 (EtOH). Rf (hexane/Et2O 1:1) 0.31. UV/VIS (hexane): lmax
318 (sh, 3.70), 262 (4.19); lmin 253 (4.18). IR (KBr): 2917w, 1727s, 1434m, 1258s, 1228m, 1198w, 1132w, 1099w,
1049w, 752w, 598w. 1H-NMR (300 MHz, CDCl3): 7.59 (d, J(2,3) ˆ 6.3, H C(3)); 6.38 (d, J(7,8) ˆ 6.7, H C(7));
6.37 (dd, J(1,2) ˆ 10.2, J(2,3) ˆ 6.4, H C(2)); 6.33 (d, J(7,8) ˆ 6.7, H C(8)); 6.06 (d, J(1,2) ˆ 10.2, H C(1));
5.61 (s, H C(10)); 4.24 (s, (MeS)2CH); 3.75, 3.74 (2s, MeOCO); 2.17, 1.88 (2s, (MeS)2CH); 2.02
(s, Me C(9)). 13C-NMR (75 MHz, CDCl3): 167.65, 167.06 (2s, MeOCO); 143.08 (s); 140.33 (d); 139.48 (s);
135.67 (d); 133.95 (s); 130.57 (d); 129.71 (s); 129.62 (d); 128.05 (s); 126.78 (d, 2 C); 125.30 (s); 56.07
.
‡
(d, (MeS)2CH); 52.21, 52.15 (2q, MeOCO); 24.11 (q); 15.57 (q); 11.00 (q). EI-MS: 390 (6, M ), 343 (7), 283
(100).
Data of 26a: Orange crystals. In thermal equilibrium in CDCl3 at 258 with 35% of 26b. M.p. 136.9 ± 137.88
(hexane). Rf (hexane/Et2O 1:1) 0.29. IR (KBr): 1714s, 1438m, 1268s, 1205w, 1135w, 1096w, 1056w, 781w, 744w.
1H-NMR (600 MHz, CDCl3; taken from the mixture with 26b): 7.47 (d, J(2,3) ˆ 5.8, H C(3)); 6.81 (d, J(8,9) ˆ
4
11.9, H C(9)); 6.55 (dd, J(8,9) ˆ 11.9, J(6,8) ˆ 1.0, H C(8)); 6.38 (dd, J(1,2) ˆ 10.3, J(2,3) ˆ 5.8, H C(2));
6.02 (d, J(1,2) ˆ 10.3, H C(1)); 5.86 (s, H C(6)); 4.69 (s, Me2SCH); 3.72, 3.67 (s, 2 MeOCO); 2.15, 1.92
.
‡
‡
(s, Me2SCH); 2.02 (d, J ˆ 1.1, Me C(7)). EI-MS: 390 (8, M ), 343 (100, [M MeS] ).
Data of Dimethyl 6-[Bis(methylthio)methyl]-9-methylheptalene-1,2-dicarboxylate (26b; in equilibrium in
CDCl3 at 258 with 65% of 26a): 1H-NMR (600 MHz, CDCl3; taken from the mixture with 26a): 6.62
(dd, J(3,4) ˆ 11.6, J(4,5) ˆ 6.3, H C(4)); 6.58 (d, J(3,4) ˆ 11.6, H C(3)); 6.41 (d, J(7,8) ˆ 6.8, H C(7)); 6.17
(2d, superimposed, J ꢀ 6.4, H C(5), H C(8)); 5.68 (s, H C(10)); 4.39 (s, Me2SCH C(6)); 3.81, 3.73
(s, MeOCO); 2.20, 2.05 (s, Me2SCH C(6)); 2.00 (s, Me C(9)).
1.21. Dimethyl 6-Formyl-9-methylheptalene-4,5-dicarboxylate (27). The hydrolysis of 25 (567 mg,
1.45 mmol) with HgO (629 mg, 2.90 mmol) and BF3 ´ OEt2 (197 mg, 2.90 mmol) in THF/H2O was performed
according to the procedure described for 20a to yield 27 (411 mg, 91%). Orange crystals. M.p. 201.3 ± 202.18
(Et2O). Rf (hexane/EtOAc 4 : 6) 0.49. UV/VIS (hexane): lmax 400 (sh, 3.00), 330 (sh, 3.60), 272 (4.30); lmin 252
(4.24). IR (KBr): 1732s, 1712m, 1681s, 1641w, 1604w, 1576w, 1440w, 1276s, 1256m, 1232m, 1195w, 1168w, 1134w,
1
1108w, 1056m, 860w, 746w. H-NMR (600 MHz, CDCl3): 9.43 (s, CHO); 7.52 (d, J(2,3) ˆ 6.4, H C(3)); 7.00
(d, J(7,8) ˆ 6.6, H C(7)); 6.48 (d, J(7,8) ˆ 6.6, H C(8)); 6.36 (dd, J(1,2) ˆ 10.4, J(2,3) ˆ 6.4, H C(2)); 5.99
(d, J(1,2) ˆ 10.2,
H
C(1)); 5.68 (s, H C(10)); 3.72, 3.58 (2s, MeOCO); 2.10 (s, Me C(9)). 1H-NOE
(600 MHz, CDCl3): CHO ! H C(7); Me C(9) ! H C(10), H C(8); H C(10) ! H C(1), Me C(9).
13C-NMR (75 MHz, CDCl3): 190.81 (d, CHO); 167.26, 167.00 (2s, MeOOC); 147.45 (s); 146.66 (d); 140.44 (d);
135.36 (s); 134.81 (d); 134.76 (s); 133.06 (s); 132.98 (d); 131.46 (d); 130.55 (s); 127.44 (s); 126.92 (d); 52.29, 52.12
.
‡
‡
(2q, MeOCO); 25.10 (q, Me C(9)). EI-MS: 312 (3, M ), 253 (100, [M MeOCO] ). The structure of 27 was
confirmed by an X-ray crystal-structure analysis (cf. Fig. 2).
1.22. Dimethyl 9-Methyl-6-[(E,E)-4-phenylbuta-1,3-dienyl]heptalene-4,5-dicarboxylate (28). To the two-
phase system of 27 (62.5 mg, 0.2 mmol) in CH2Cl2/2n NaOH (1:1, 20 ml), a soln. of [(E)-3-phenylprop-2-
enyl]triphenylphosphonium bromide (551 mg, 1.2 mmol) in CH2Cl2 (10 ml) was added at 258 under stirring.
After 2 h, the org. phase was separated and the solvent evaporated. CC (silica gel; hexane/Et2O 1:1) yielded a
mixture of (1Z,3E)-28 and (1E,3E)-28, which was stirred with a catalytic amount of I2 in hexane/Et2O at 258
overnight to yield pure (1E,3E)-28 (78 mg, 95%). Orange crystals. M.p. 200.1 ± 201.08 (hexane). Rf (hexane/
Et2O 1:1) 0.28. UV/VIS (hexane): lmax 410 (sh, 3.90), 330 (4.51), 246 (4.35); lmin 286 (4.22). IR (KBr): 3021w,
2949w, 1737s, 1714s, 1434m, 1271s, 1234m, 1200w, 1125m, 1097w, 1053w, 1008w, 990w, 754w, 690w. 1H-NMR
2
(600 MHz, CDCl3) ): 7.66 (d, J(2,3) ˆ 6.4, H C(3)); 7.36 (m, 2 arom. H); 7.30 (m, 2 arom. H); 7.21 (m, 1 ar-
om. H); 6.80 (dm-like, J(3',4') ˆ 15.5, H C(3')); 6.54 (d, J(3',4') ˆ 15.5, H C(4')); 6.48 (dd, J(1,2) ˆ 10.2,
J(2,3) ˆ 6.4, H C(2)); 6.45 (m, H C(1',2')); 6.37 (d, J(7,8) ˆ 6.9, H C(8)); 6.29 (d, J(7,8) ˆ 6.9, H C(7));
6.09 (d, J(1,2) ˆ 10.2, H C(1)); 5.66 (s, H C(10)); 3.75, 3.56 (2s, MeOCO); 2.05 (s, Me C(9)). 13C-NMR
(150 MHz, CDCl3): 167.87, 167.29 (2s, MeOCO); 140.75 (d, C(3)); 140.49 (s); 139.22 (s); 137.57 (s); 135.14
(d, C(1)); 134.74 (s); 133.56 (d, C(1')); 133.44 (d, C(4')); 132.25 (d, C(10)); 131.35 (d, C(2)); 130.38 (d, C(7));
130.08 (s); 129.03 (d, C(2')); 128.99 (s); 128.96 (d, C(3')); 128.90 (d, C(8)); 128.82 (d, 2 arom. C); 127.70
(d, 1 arom. C); 126.86 (s); 126.50 (d, 2 arom. C); 52.52, 52.32 (2q, MeOCO); 24.76 (q, Me C(9)). EI-MS: 413
.
‡
‡
(14), 412 (56, M ), 353 (100, [M MeOCO] ), 321 (58). The structure of (1E,3E)-28 was confirmed by an X-
ray crystal-structure analysis (cf. Fig. 3).

Helvetica Chimica Acta ± Vol. 82 (1999)
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3
2. X-Ray Crystal-Structure Determinations ) of 12, 27, and 28. ± All measurements were made on a Rigaku
AFC5R diffractometer with graphite-monochromated MoKa radiation (l ˆ 0.71069 Š) and a 12-kW rotating
anode generator. The w/2q scan mode was employed and the intensities of three standard reflections were
measured after every 150 reflections and remained stable throughout each data collection. The intensities were
corrected for Lorentz and polarization effects, but not for absorption. The data collection and refinement
parameters are given in the Table.
Table 1. Crystallographic Data of 12, 27, and 28
Substance
12
27
28
Crystallized from
CH2Cl2/Et2O/hexane
C23H26O5
382.45
yellow, tablet
0.15 Â 0.40 Â 0.50
173(1)
CH2Cl2/hexane
C18H16O5
312.32
red, prism
0.42 Â 0.42 Â 0.48
296(1)
monoclinic
P21/n
CH2Cl2/Et2O/hexane
C27H24O4
412.48
red, prism
0.42 Â 0.42 Â 0.48
173(1)
Empirical formula
Formula weight [g mol
Crystal color, habit
Crystal dimensions [mm]
Temp. [K]
1
]
Crystal system
Space group
monoclinic
P21/c
triclinic
Å
P1
Z
4
4
2
Reflections for cell determination
25
25
25
2q Range for cell determination [8]
Unit cell parameters a [Š]
36 ± 40
36 ± 40
13.261(1)
8.570(2)
14.110(1)
90
99.010(7)
90
1583.8(4)
1.310
39 ± 40
10.429(2)
12.670(3)
9.377(1)
93.77(2)
102.09(2)
109.83(2)
1110.7(4)
1.233
9.568(4)
20.896(3)
10.592(3)
90
107.00(2)
90
2025.2(8)
1.254
0.0874
b [Š]
c [Š]
a [8]
b [8]
g [8]
V [Š3]
Dx [g cm
3
]
3
m(MoKa) [mm
2q(max) [8]
]
0.0957
55
0.0819
55
55
Total reflections measured
Symmetry independent
reflections
5069
4655
4040
3633
5374
5095
Reflections used [I > 2s(I)]
Parameters refined
Final R
3346
358
0.0442
0.0402
1.647
1.08(7) Â 10
2436
273
0.0430
0.0355
1.863
2.5(1) Â 10
3603
377
0.0438
0.0383
1.887
1.4(2) Â 10
wR
Goodness of fit
Secondary extinction
coefficient
6
6
6
Final Dmax/s
D1 (max; min) [e Š
s(d(C C)) [Š]
0.0002
0.26; 0.20
0.002 ± 0.003
0.0006
0.18; 0.13
0.002 ± 0.003
0.0003
0.23; 0.25
0.002 ± 0.004
3
]
Each structure was solved by direct methods with SHELXS86 [18], which revealed the positions of all non-
H-atoms. The non-H-atoms were refined anisotropically. All of the H-atoms were located in difference electron-
density maps, and their positions were allowed to refine together with individual isotropic displacement
3
)
Crystallographic data (excluding structure factors) for the structures of compounds 12, 27, and 28 have been
deposited with the Cambridge Crystallographic Data Centre as supplementary publication No. CCDC-
130627, 130628, and 130629, respectively. 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).

1706
Helvetica Chimica Acta ± Vol. 82 (1999)
parameters. Refinement of each structure was carried out on F with full-matrix least-squares procedures, which
minimized the function Sw (j Fo j j Fc j ), where w ˆ [s2 (Fo) ‡ (pFo)2] 1. A correction for secondary extinction
was applied in each structure.
Neutral atom scattering factors for non-H-atoms were taken from [19], and the scattering factors for H-
atoms were taken from [20]. Anomalous dispersion effects were included in Fc [21]; the values for f ' and f '' were
those of [22]. All calculations for 28 were performed with the TEXSAN crystallographic software package [23],
while teXsan was employed for 12 and 27 [24].
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Â
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Woodlands, Texas, 1997.
Received July 9, 1999