O-Trimethylsilylenol ethers as versatile building blocks in a modular preparation of polyenic backbone

Article abstract of DOI:10.1016/j.tet.2003.12.008

Versatility and synthetic potential of 1-(trimethylsilyloxy)-1,3-butadiene, 1-(trimethylsilyloxy)penta-1,3-diene, and their methyl substituted derivatives have been demonstrated in a modular synthetic methodology of stereodefined π-conjugated unsymmetrical, symmetrical two-dimensional, and octupolar polyenal structure.

Full text of DOI:10.1016/j.tet.2003.12.008

Tetrahedron 60 (2004) 1931–1939
O-Trimethylsilylenol ethers as versatile building blocks in a
modular preparation of polyenic backbone
Beata W. Domagalska,a Ludwik Syperb and Kazimiera A. Wilka
,
*
a
´
Institute of Organic and Polymer Technology, Wrocl⁄aw University of Technology, Wybrzez˙e Wyspianskiego 27, 50-370 Wrocl⁄aw, Poland
Institute of Organic Chemistry, Biochemistry and Biotechnology, Wrocl⁄aw University of Technology, Wybrzez˙e Wyspianskiego 27, 50-370
b
´
Wrocl⁄aw, Poland
Received 14 August 2003; revised 7 November 2003; accepted 4 December 2003
Abstract—Versatility and synthetic potential of 1-(trimethylsilyloxy)-1,3-butadiene, 1-(trimethylsilyloxy)penta-1,3-diene, and their methyl
substituted derivatives have been demonstrated in a modular synthetic methodology of stereodefined p-conjugated unsymmetrical,
symmetrical two-dimensional, and octupolar polyenal structure.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
stereodefined (pure all-E) p-conjugated polyenes16 we
have devised new methodology for the synthesis of a
polyenic backbone starting from 5,5-diethoxypenta-2-enal
as a template and using 1-(trimethylsilyloxy)-1,3-butadiene
as a building block. This modular method was successfully
applied to the synthesis of linear, unsymmetrical amphi-
philic conjugated all-E polyenals (v,v0-(p-alkoxyphenyl)-
polyenals)16 containing up to eight double bonds.
The conjugated polyenic backbone is an important struc-
tural unit in macrolide antibiotics and various classes of
natural products (e g., retinoic acids, chrysophysarin A).1 It
has also been shown that conjugated polyenes can be used as
model compounds for a variety of applications including
electron transfer,2 light harvesting,3 nonlinear optics,4,5 and
conductivity2 and are potentially useful compounds for
electronic and non-linear optical materials.6 Thus, it is not
surprising that considerable efforts have been made to
search for stereoselective methods of synthesis of such
conjugated systems.
The main purpose of the present contribution is to illustrate
the versatility and the efficient synthetic potential of
O-trimethylsilylenol ethers (1-(trimethylsilyloxy)-1,3-buta-
diene 8, 1-(trimethylsilyloxy)penta-1,3-diene 4 and their
methyl substituted derivatives 5–7) for the stereoselective
preparation of unsymmetrical as well as symmetrical and
octupolar conjugated polyenals with and without the methyl
groups in the polyenic backbone. We generalize the
modular method by use of 1-(trimethylsilyloxy)penta-1,3-
diene 4, 3-methyl-1-(trimethylsilyloxy)-1,3-butadiene 5,
2-methyl-1-(trimethylsilyloxy)-1,3-butadiene 6, 2-methyl-
1-(trimethylsilyloxy)penta-1,3-diene 7 as building blocks
and new templates (4-hexyloxy-3-methoxybenzaldehyde
1(0), 3-(4-hexyloxy-3-methoxyphenyl)propenal 1(1), 2-meth-
oxy-5-methyl-isophtalaldehyde 2, and 2,4,6-trimethoxy-
1,3,5-benzenetricarbaldehyde 3). These building blocks
lead to new conjugated polyenes with an angular methyl
group — very important class of carotenoid-type polyenes.
We are also interested in the synthesis of symmetrical two-
dimensional conjugated polyenals and octupolar structures.
The use of template with two reactive carbonyl moieties
(2) leads to new symmetrical, conjugated polyenals —
precursors of acceptor or donor substituted polyenes
which represent an approach to a molecular wire.17 The
new octupolar structures that are of particular interest in
the field of nonlinear optics due to their potentially large two
In the literature, the most common strategy of double-bond
formation in the conjugated system is the Wittig reaction
or one of its variants (Wittig–Horner, WH; Horner–
Wadsworth–Emmons, HWE).7 A site of unsaturation in
the conjugated structure can also be generated by means of,
for example, ring opening metathesis oligomerization,8
retro-Diels–Alder reaction,9 transition-metal-catalyzed
reaction,10 homocoupling reaction of unsaturated silanes11
or allylboration reaction12 and hydrozirconation-cross-
coupling.13 Knoevenagel condensation affords a possibility
for incorporation of double bond, and donor or acceptor
entity at one time and is commonly used to prepare
conjugated polyenes with various functional groups.14,15
In our previous studies dealing with the synthesis of
Keywords: O-Trimethylsilyl enol ethers; Unsymmetrical conjugated
polyenes; Symmetrical conjugated polyenes; Octupolar conjugated
polyenes.
*
Corresponding author. Tel.: þ48-71-3202828; fax.: þ48-71-3203678;
e-mail address: kazimiera.wilk@pwr.wroc.pl
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2003.12.008

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B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
Scheme 1. The general synthetic approach for (A) unsymmetrical carotenoid-type polyenals, (B) symmetrical conjugated polyenals and (C) octupolar
conjugated polyenals. Templates T and silyl enol ethers are presented in Table 1.
or three-dimensional quadratic nonlinearities can be
obtained from the template with three reactive carbonyl
moieties.
camphorsulfonic acid (CSA). In the case of PPTS, as the
catalyst at 25 8C, the first step has been completed within
154 h for template 3 (see Table 2). Increasing temperature
up to 50 8C makes the reaction time shorter (130 h), but
unfortunately, the yield was diminished (Table 2). It is
worth noting that CSA catalyzes the studied reaction
effectively at 25 8C; tenfold reaction time decrease, high
yield (see Table 2).
2. Results and discussion
Scheme 1 presents the synthetic approach for unsym-
metrical carotenoid-type structures (A), as well as
symmetrical (B) and octupolar (C) conjugated polyenals.
Thus, in this modular synthesis, which involves reactive
silyl enol ethers 4–8 as building blocks, and aldehyde
comprising conjugation in its structure (1(0), 1(1), 2, 3) as
templates, a series of conjugated polyenals presented in
Table 1 are obtained.
The second step (reaction (ii) in Scheme 1) represents the
reaction of the nucleophilic building block to the above
mentioned acetal in the presence of catalytic amounts of
ZnCl2, giving rise to d-ethoxy-a,b-unsaturated aldehydes.
The use of silyl enol ethers 4–8, indicated in the first
paragraph, made it possible to achieve in one step the carbon
chain elongation of up to four atoms. Then, the 4–7 silyl
enol ethers led, additionally to the methyl group introduc-
tion in the polyenic backbone and, furthermore, to the
carotenoid-like structures 8–11, 14, 16 and polyenals 12.
The building block 8 is commercially available and the rest
of used silyl enol ethers are easy to obtain from appropriate
aldehydes according to method described in the literature.18
In order to complete the synthesis of conjugated polyenals,
Each particular step of the designed iterative process,
independent of the applied template, involves three steps.
The first one — the slowest reaction step in the whole
modular approach (reaction (i) in Scheme 1) — denotes the
acetalization of the respective template (aldehyde compris-
ing conjugation in its structure) with triethyl orthoformate in
the presence of pyridinium p-toluenesulfonate (PPTS) or

B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
1933
Table 1. Templates 1–3 and building blocks 4–6 leading to polyenals 8–16 by modular synthesis
water or/and ethanol are to be eliminated, double bonds
shifted and the acetal moiety hydrolyzed in a cascade of four
simultaneous reactions. The intermediates are carbocations,
which are stable because of their allylic character.11 The
mentioned process carried out in the presence of pyridinium
hydrobromide12 (reaction (iii) Scheme 1) gave thermo-
dynamically stable pure all-E isomers comprising two,
three, four, five, six, seven and eight double bonds in one
conjugated chain. The overall yields for the given series of
conjugated polyenes 8–11, 12, 13, 14, 15 and 16 ranged
between 53–75%, 43–62%, 51–74%, 49–72%, 41–69%
and 40–67%, respectively.
All synthesized polyenals 8–16 were purified by medium
pressure column chromatography (MPLC) or/and radial
chromatography in darkness under N2 and identified

1934
B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
Table 2. Experimental conditions of template 1–3 acetalization
We do not observe any bands between 1400 and 1420 cm21
and 660 and 730 cm21 what confirms the absence of Z
isomer. All spectroscopic analysis indicate all-E configu-
ration for the studied compounds.
Template
Catalyst T (8C) ta (h) Yieldb
PPTSc
CSAd
25
25
9
0.5
90
93
3. Conclusion
1(0)
Summing up, we have described the use of O-trimethylsilyl
enol ethers as versatile building blocks in modular synthesis
of unsymmetrical, symmetrical and octupolar conjugated
polyenals containing long polyenic backbones. In spite of
difficulties with purity of conjugated polyenes MPLC and
radial chromatography proved effective purification methods
(purity was confirmed by elemental analysis, ESI-MS, NMR
and UV–vis spectroscopy). Thus, obtained and purified
derivatives, identified by NMR, UV–vis and IR spectro-
scopy, represent in ground state only one all-E isomer.
PPTSc
CSAd
25
25
18
1.5
94
96
1(1)
PPTSc
PPTSc
CSAd
25
50
25
35
8.5
2.5
89
85
93
The unsymmetrical polyenals are convenient reagents for the
synthesis of push–pull structures.15,20 Push–pull polyenes
as well as symmetrical and octupolar polyenals and their
derivatives play important role as: molecular wires, novel
NLO materials or electroluminescent material for light-
emitting diodes.21–23
2
PPTSc
PPTSc
CSAd
25
50
25
154
130
10
87
85
90
4. Experimental
4.1. General methods and materials
3
Starting materials were of the highest commercial quality
and were used without further purification. All reactions
were carried out under a protective atmosphere of N2 gas
using oven-dried glassware. Mps were determined on a
Kofler block and are uncorrected. Elemental analyses were
carried out with a Perkin–Elmer 2400 CHN analyzer
(Norwalk, CT). Chromatographic purification was accom-
plished by medium pressure column chromatography
a
The progress of reaction was followed by TLC on silica gel with ethyl
acetate/hexane (v/v, 3:1) as eluent.
Isolated.
Pyridinium p-toluenesulfonate.
Camphorsulfonic acid.
b
c
d
unambiguously by NMR. The structure and stereochemistry
of conjugated polyenals 8–16 were studied by NMR
spectroscopy using one- (1H, 13C) and two-dimensional
spectra (1H–1H and 1H–13C correlated spectroscopy—
COSY). At 300 MHz these two methods allowed identifi-
cation of almost all protons of the studied polyenic chains
and determination of the coupling constants JCHvCH (14.1–
15.4 Hz) and JCH–CH (10.1–11.2 Hz) which are charac-
teristic for all-E structures.13 The stereochemical homo-
geneity of all obtained aldehyde structures was evidenced
by the presence of a single doublet (at about 9.6 ppm)
corresponding to the CHO. As in other all-E polyenes
described in the literature the UV–vis spectra of compounds
8–16 are characterized by an intense, structureless and
broad absorption band in the visible and ultraviolet
region.15,19 The p–pp transition is responsible for the first
absorption band.15,19 Symmetry of the first absorption band
and lack of the additional bands in the longer wavelength
region of the spectra evidence the existence of all-E isomer
in the CHCl3 solution. The IR spectrum in KBr of all studied
compounds is very complex but detailed analysis confirms
the structure and all-E configuration for the new polyenals
8–15. The IR spectrum of all polyenals has absorption band
between 1665 and 1685 cm21 indicating the presence of
long conjudated system (CvC–CvC and CvC–CvO).
(MPLC, Buchi Labortechnik AG, silica gel, flow rate
20 mL min21, eluent—hexane/ethyl acetate, 3:1) or/and
radial chromatography (Chromatotron, Harrison Research
Inc., N2, 60 rpm, 2 mm layer of Silica Gel 60 GF254,
flow rate 6 mL min21, eluent — hexane/ethyl acetate, 4:1).
Electrospray ionization (ESI) spectra were obtained with a
Finnigan TSQ-700 mass spectrometer. Nuclear magnetic
resonance (NMR) spectra were recorded with a Bruker
AMX-300 spectrometer (Karlsruhe, Germany). 1H chemical
shifts (at 300.13 MHz) are referenced in CDCl3 to residual
protons of CDCl3 (7.24 ppm). The UV–Vis absorption
spectra of freshly prepared solutions of all obtained
polyenes were measured in CH3Cl at room temperature
using UV–Vis Unicam (Thermo Spectronic) spectro-
photometer. IR spectra were obtained on FT-IR Nexus
(Thermo Nicolet) spectrophotometer.
¨
4.2. General procedure for the preparation of
unsymmetrical conjugated polyenals 8(n)-12(n)
A mixture of appropriate aldehyde (template 1(m), or
polyenal 8(n)–12(n) (22 mmol), CH(OEt)3 (10 mL,
60 mmol) and catalyst (PPTS or CSA, 100 mg) in anhyd
Et2O (10 mL) was stirred at rt for 16–120 h (reaction

B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
1935
progress was controlled by TLC analysis). Then the mixture
was poured into 5% aq ammonium hydroxide solution
(50 mL) and the aqueous layer was extracted with Et2O
(4£80 mL). The combined organic layers were washed with
brine, dried with K2CO3 and the solvent was evaporated
under reduced pressure. The appropriate silyl enol ether (4,
5, 6, or 7) (36 mmol) in anhyd Et2O (20 mL) was then added
dropwise to a well-stirred, ice-cooled solution of bis-acetal
and ZnCl2 (1.0 g, 7.34 mmol) in anhyd Et2O (20 mL). After
36 h stirring at 5 8C, the reaction mixture was poured into
the ice–water (100 mL). The organic phase was shaken
with sat. aq NaHCO3 and water, dried with MgSO4 and the
solvent was removed in vacuo. The obtained brown oil was
added to a solution of a pyridine hydrobromide (0.10 g,
0.31 mmol) in acetone containing 0.2 mL of water. The
mixture was stirred at 40 8C for 20–46 h, then poured into
cold water (25 mL) and extracted with anhyd Et2O
(2£25 mL). The organic phase was washed with cold
water, dried with MgSO4 and evaporated. The residue was
purified by medium pressure column chromatography or
radial chromatography (hexane/EtOAc, 3:1 v/v).
8.1 Hz, CHO), 6.82 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.80
(1H, s, ArCH), 6.76 (1H, d, J¼8.6 Hz, ArH), 6.73–6.78
(2H, m, ((Me)CCHvCHCHv)2), 6.71 (1H, dd, J¼14.9,
7.9 Hz, MeCCHvCH), 6.70 (1H, d, J¼15.0 Hz,
CHvCHCHO), 6.66 (1H, d, J¼14.9 Hz, MeCCHvCH),
6.65 (1H, d, J¼3.0 Hz), 6.44 (2H, 2£d, J¼7.9 Hz,
(CHvC(Me)CHvCH)2), 6.22 (1H, dd, J¼14.9, 8.1 Hz,
CHCHO), 3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89 (3H, s, OMe),
1.90 (9H, s, 3£CHvCMe), 1.30–1.80 (8H, m, Me(CH2)4),
0.90 (3H, t, J¼6.9 Hz, Me(CH2)4). lmax(CHCl3)¼422 nm,
1¼4.9£105.
4.2.4. (2E,4E,6E,8E,10E,12E,14E,16E)-17-(4-Hexyloxy-
3-methoxyphenyl)-4,8,12,16-tetramethyl-heptadeca-
2,4,6,8,10,12,14,16-octaenal (8(4)). Brown solid, mp
79–84 8C, yield 54%. Anal. Calcd for C34H44O3 (500.72):
C, 81.56; H, 8.86. Found: C, 81.3; H, 9.0. ESI-MS:
MHþ¼501.4. nmax (KBr) 3020, 2935, 2855, 1665, 1590,
1510, 1465, 1395, 1300, 1267, 1465, 1260, 1140, 1120,
1030, 970, 850, 645 cm21. dH (300 MHz, CDCl3) 9.40
(1H, d, J¼8.0 Hz, CHO), 6.98 (1H, d, J¼15.0 Hz,
CHvCHCHO), 6.82 (1H, dd, J¼9.0, 3.0 Hz, ArH), 6.80
(1H, s, ArCH), 6.73–6.78 (4H, m, (CHCHvC(Me)CH)3þ
ArH), 6.65 (1H, d, J¼3.0 Hz, ArH), 6.60 (3H, 3£d, J¼
14.9 Hz, (CHvCHCHvCMe)3), 6.42 (3H, 3£d, J¼7.9 Hz,
(CHvC(Me)CHvCH)3), 6.22 (1H, dd, J¼8.1, 14.9 Hz,
CHCHO), 3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89 (3H,
s, OMe), 1.90 (12H, s, 4£CHvCMe), 1.30–1.80 (8H,
m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz, Me(CH2)4).
4.2.1. (2E,4E)-5-(4-Hexyloxy-3-methoxyphenyl)-4-
methyl-penta-2,4-dienal (8(1)). Brown solid, mp 30–
35 8C, yield 75%. Anal. Calcd for C19H26O3 (302.4): C,
75.46; H, 8.67. Found: C, 75.26; H, 8.85. ESI-MS:
MHþ¼303.2. nmax (KBr) 2940, 2851, 1668, 1591, 1507,
1470, 1395, 1310, 1249, 1180, 1028, 968, 850, 795,
640 cm21. dH (300 MHz, CDCl3) 9.40 (1H, d, J¼8.1 Hz,
CHO), 7.20 (1H, d, J¼15.0 Hz, CHvCHCHO), 6.82 (1H,
dd, J¼8.9, 3.0 Hz, ArH), 6.80 (1H, s, ArCH), 6.76 (1H, d,
J¼8.6 Hz, ArH), 6.65 (1H, d, J¼3.0 Hz), 6.20 (1H, dd,
J¼8.0, 15.1 Hz, CHCHO), 3.97 (2H, t, J¼6.5 Hz, CH2O),
3.89 (3H, s, OMe), 1.90 (3H, s, CHvCMe), 1.30–1.80
(8H, m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz, Me(CH2)4).
l
max(CHCl3)¼445 nm, 1¼5.7£105.
4.2.5. (2E,4E)-5-(4-Hexyloxy-3-methoxyphenyl)-3-
methyl-penta-2,4-dienal (9(1)). Brown solid, mp
32–36 8C, yield 74%. Anal. Calcd for C19H26O3 (302.41):
C, 75.46; H, 8.67. Found: C, 75.2; H, 8.9. ESI-MS:
MHþ¼303.2. nmax (KBr) 2950, 2862, 1663, 1590, 1508,
l
max(CHCl3)¼354 nm, 1¼2.8£105.
1470, 1395, 1305, 1250, 1150, 1025, 965, 850, 642 cm21
.
4.2.2. (2E,4E,6E,8E)-9-(4-Hexyloxy-3-methoxyphenyl)-
4,8-dimethyl-nona-2,4,6,8-tetraenal (8(2)). Brown solid,
mp 49–54 8C, yield 67%. Anal. Calcd for C24H32O3
(368.5): C, 78.22; H, 8.75. Found: C, 78.0; H 8.9. ESI-
MS: MHþ¼369.22. nmax (KBr) 3020, 2949, 2860, 1730,
1640, 1620, 1600, 1537, 1510, 1250, 1180, 1024, 975, 835,
795, 645, 645 cm21. dH (300 MHz, CDCl3) 9.42 (1H, d,
J¼8.1 Hz, CHO), 6.98 (1H, d, J¼15.0 Hz, CHvCHCHO),
6.82 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.80 (1H, s, ArCH), 6.76
(1H, d, J¼8.6 Hz, ArH), 6.70 (1H, dd, J¼14.9, 7.9 Hz,
MeCCHvCH), 6.66 (1H, d, J¼14.9 Hz, MeCCHvCH),
6.65 (1H, d, J¼3.0 Hz, ArH), 6.44 (1H, d, J¼7.9 Hz,
CHvC(Me)), 6.22 (1H, dd, J¼14.9, 8.1 Hz, CHCHO),
3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89 (3H, s, OMe), 1.90
(6H, s, 2£CMe), 1.30–1.80 (8H, m, Me(CH2)4), 0.90
dH (300 MHz, CDCl3) 9.42 (1H, d, J¼8.0 Hz, CHO), 6.82
(1H, dd, J¼8.7, 3.0 Hz), 6.76 (1H, d, J¼8.6 Hz, ArH), 6.70
(1H, d, J¼15.1 Hz, ArCH), 6.65 (1H, d, J¼3.0 Hz, ArH),
6.63 (1H, d, J¼15.4 Hz, ArCHvCH), 6.32 (1H, d, J¼
8.0 Hz, CHCHO), 3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89
(3H, s, OMe), 1.88 (3H, s, CHvCMe), 1.30–1.80 (8H,
m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz, Me(CH2)4).
l
max(CHCl3)¼345 nm, 1¼2.5£105.
4.2.6. (2E,4E,6E,8E)-9-(4-Hexyloxy-3-methoxyphenyl)-
3,7-dimethyl-nona-2,4,6,8-tetraenal (9(2)). Brown solid,
mp 49–54 8C, yield 68%. Anal. Calcd for C24H32O3
(368.52): C, 78.22; H, 8.75. Found: C, 78.0; H, 8.9.
ESI-MS: MHþ¼369.2. nmax (KBr) 2930, 2890, 1670, 1638,
1620, 1510, 1470, 1380, 1253, 1135, 999, 836, 792,
645 cm21. dH (300 MHz, CDCl3) 9.45 (1H, d, J¼8.0 Hz,
CHO), 6.82 (1H, dd, J¼8.9, 3.0 Hz), 6.77 (1H, d, J¼
8.6 Hz), 6.75 (1H, dd, J¼9.0, 14.8 Hz, CHvCHC(Me)),
6.71 (1H, d, J¼15.3 Hz, ArCH), 6.65 (1H, d, J¼3.0 Hz),
6.64 (1H, d, J¼8.9 Hz, MeCvCHCH), 6.63 (1H, d,
J¼15.0 Hz, ArCHvCH), 6.41 (1H, d, J¼15.0 Hz,
CHC(Me)vCHCHO), 6.32 (1H, d, J¼7.9 Hz, CHCHO),
3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89 (3H, s, OMe), 1.90
(6H, s, 2£CHvCMe), 1.30–1.79 (8H, m, Me(CH2)4), 0.90
(3H, t, J¼6.9 Hz, Me(CH2)4). lmax(CHCl3)¼384 nm, 1¼
4.0£105.
(3H, t, J¼6.9 Hz, Me(CH2)4).
1¼4.2£105.
lmax(CHCl3)¼394 nm,
4.2.3. (2E,4E,6E,8E,10E,12E)-13-(4-Hexyloxy-3-methoxy-
phenyl)-4,8,12-trimethyl-trideca-2,4,6,8,10, 12-heksaenal
(8(3)). Brown solid, mp 62–68 8C, yield 60%. Anal. Calcd
for C29H38O3 (434.61): C, 80.14; H, 8.81. Found: C, 79.9;
H, 8.9. ESI-MS: MHþ¼435.3. nmax (KBr) 3025, 2960,
2937, 2853, 1677, 1586, 1508, 1470, 1390, 1302, 1290,
1254, 1240, 1175, 1150, 1120, 1010, 990, 920, 855, 795,
650, 625 cm21. dH (300 MHz, CDCl3) 9.40 (1H, d, J¼

1936
B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
4.2.7. (2E,4E,6E,8E,10E,12E)-13-(4-Hexyloxy-3-methoxy-
phenyl)-3,7,11-trimethyl-trideca-2,4,6,8,10, 12-heksaenal
(9(3)). Brown solid, mp 62–66 8C, yield 59%. Anal. Calcd
for C29H38O3 (434.62): C, 80.14; H, 8.81. Found: C, 79.9;
H, 9.0. ESI-MS: MHþ¼435.3. nmax (KBr) 3020, 2950,
2931, 2860, 1675, 1585, 1510, 1465, 1390, 1305, 1292,
1253, 1170, 1135, 1015, 998, 920, 855, 645 cm21. dH
(300 MHz, CDCl3) 9.45 (1H, d, J¼8.0 Hz, CHO), 6.82 (1H,
dd, J¼8.9, 3.0 Hz, ArH), 6.76 (1H, d, J¼8.7 Hz, ArH), 6.72
(2H, dd, J¼14.8, 9.0 Hz, CHvCHC(Me)), 6.70 (1H, d,
J¼15.3 Hz, ArCH), 6.65 (3H, m, (C(Me)vCHCHvCH)2þ
ArH), 6.64 (1H, d, J¼15.0 Hz, ArCHvCH), 6.41 (2H,
m, (C(Me)vCHCHvCH)2), 6.30 (1H, d, J¼7.9 Hz,
CHCHO), 3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89 (3H, s,
OMe), 1.90 (9H, s, 3£CHvCMe), 1.30–1.79 (8H, m,
Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼415 nm,
1¼5.1£105.
(1H, d, J¼14.7 Hz, ArCH), 6.66 (1H, d, J¼15.0 Hz,
C(Me)CH), 6.65 (1H, d, J¼3.0 Hz), 6.59 (2H, m,
CHvCHCHvCH), 6.30 (1H, d, J¼9.2 Hz, CHvCMe),
3.97 (2H, t, J¼6.5 Hz, CH2O), 3.89 (3H, s, OMe), 1.90
(6H, s, (CHvCHCHvCMe)2), 1.30–1.79 (8H, m,
Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼415 nm,
1¼2.8£105.
4.2.11. (2E,4E,6E,8E,10E,12E,14E)-15-(4-Hexyloxy-3-
methoxyphenyl)-2,6,10-trimethyl-pentadeca-2,4,6,8,10,
12,14-heptaenal (10(3)). Brown solid, mp 70–74 8C, yield
59%. Anal. Calcd for C31H40O3 (460.65): C, 80.83; H, 8.75.
Found: C, 81.1; H, 9.0. ESI-MS: MHþ¼461.3. nmax (KBr)
3005, 2935, 2850, 1670, 1600, 1511, 1466, 1268, 1178,
1138, 1030, 835, 795, 650 cm21. dH (300 MHz, CDCl3)
9.41 (1H, s, CHO), 6.90 (1H, d, J¼10.2 Hz, CHC(CH3)-
CHO), 6.82 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.79 (1H, dd,
J¼14.9, 9.8 Hz, ArCHvCH), 6.76 (1H, d, J¼8.6 Hz, ArH),
6.76 (2H, m, (CHvCHCHvCMe)2), 6.71 (1H, d, J¼
14.7 Hz, ArCHvCH), 6.65 (1H, d, J¼2.9 Hz), 6.63 (2H, m,
(CHvCHCHvCMe)2), 6.59 (1H, dd, J¼15.9, 9.0 Hz,
CHvCHCHvCH), 6.58 (dd, 1H, J¼14.9, 9.7 Hz,
CHvCHCHvCH), 6.41 (2H, m, (CHvC(Me)CHvCH)2),
3.97 (2H, t, J¼6.5 Hz, CH2O), 3.89 (3H, s, OMe), 1.90 (6H,
s, (CHvCHCHvCMe)2), 1.30–1.79 (8H, m, Me(CH2)4),
0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼452 nm, 1¼3.4£105.
4.2.8. (2E,4E,6E,8E,10E,12E,14E,16E)-17-(4-Hexyloxy-
3-methoxyphenyl)-3,7,11,14-tetramethyl-heptadeca-
2,4,6,8,10,12,14,16-octaenal (9(4)). Brown solid, mp 80–
85 8C, yield 55%. Anal. Calcd for C34H44O3 (500.72): C,
81.56; H, 8.86. Found: C, 81.3; H, 9.0. ESI-MS: MHþ¼
501.3. nmax (KBr) 3025, 2940, 2852, 1665, 1589, 1511,
1463, 1380, 1310, 1290, 1230, 1175, 1130, 1015, 998, 850,
795, 650 cm21. dH (300 MHz, CDCl3) 9.42 (1H, d, J¼
8.0 Hz, CHO), 6.82 (1H, dd, J¼8.9, 2.9 Hz, ArH), 6.76 (4H,
m, (CHvCHC(Me)vCH)3þArH), 6.70 (1H, d, J¼15.3 Hz,
ArCH), 6.66 (3H, m, (CHCHvCHCMe)3), 6.65 (1H, d,
J¼2.98 Hz, ArH), 6.63 (1H, d, J¼15.0 Hz, ArCHvCH),
6.41 (3H, m, (C(Me)vCHCHvCH)3), 6.32 (1H, d,
J¼8.0 Hz, CHCHO), 3.97 (2H, t, J¼6.54 Hz, CH2O), 3.89
(3H, s, OMe), 1.90 (12H, s, 4£CHvCMe), 1.30–1.79 (8H, m,
Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼438 nm,
1¼5.9£105.
4.2.12. (2E,4E,6E,8E,10E,12E,14E,16E,18E)-19-(4-Hexyl-
oxy-3-methoxyphenyl)-2,6,10,14-tetramethylheptadeca-
2,4,6,8,10,12,14,16,18-nonaenal (10(4)). Brown solid, mp
87–91 8C, yield 53%. Anal. Calcd for C36H46O3 (526.75):
C, 82.09; H, 8.80. Found: C, 81.7; H, 9.0. ESI-MS:
MHþ¼527.3. nmax (KBr) 3029, 2952, 2856, 1662, 1587,
1510, 1471, 1365, 1137, 991, 863, 790, 742, 640 cm21. dH
(300 MHz, CDCl3) 9.43 (1H, s, CHO), 6.91 (1H, d,
J¼10.2 Hz, CHC(CH3)CHO), 6.82 (1H, dd, J¼8.9,
3.0 Hz, ArH), 6.79 (1H, dd, J¼14.9, 9.8 Hz, ArCHvCH),
6.73–6.77 (4H, m, (CHvCHCHvCMe)3þArH), 6.71
(1H, d, J¼14.7 Hz, ArCHvCH), 6.62–6.66 (4H,
4.2.9. (2E,4E,6E)-7-(4-Hexyloxy-3-methoxyphenyl)-2-
methyl-hepta-2,4,6-trienal (10(1)). Brown solid, mp
40–45 8C, yield 70%. Anal. Calcd for C21H28O3 (328.45):
C, 76.79; H, 8.59. Found: C, 75.12; H, 8.69. ESI-MS:
MHþ¼329.2. nmax (KBr) 3000, 2930, 2860, 1720, 1660,
1604, 1512, 1465, 1270, 1031, 1020, 995, 845, 800,
645 cm21. dH (300 MHz, CDCl3) 9.43 (1H, s, CHO), 6.92
(1H, d, J¼11.0 Hz, CHC(CH3)CHO), 6.82 (dd, 1H, J¼8.9,
3.0 Hz, ArH), 6.80 (1H, dd, J¼10.1, 15.0 Hz, ArCHvCH),
6.76 (1H, d, J¼8.6 Hz, ArH), 6.70 (1H, d, J¼14.7 Hz,
ArCHvCH), 6.65 (1H, d, J¼3.0 Hz, ArH), 6.60 (2H, dd,
J¼15.0, 9.2 Hz, CHvCH) 3.97 (2H, t, J¼6.54 Hz, CH2O),
3.89 (3H, s, OMe), 1.90 (3H, s, CHvCMe), 1.30–1.79 (8H,
m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼369
nm, 1¼2.4£105.
m,
(CHvCHCHvCMe)3þArH),
6.59
(2H,
m,
CHvCHCHvCH), 6.40 (3H, m, (CHvC(Me)CHvCH)3),
3.97 (2H, t, J¼6.5 Hz, CH2O), 3.89 (3H, s, OMe), 1.90
(12H, s, (CHvCHCHvCMe)2), 1.30–1.79 (8H, m,
Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼467 nm,
1¼4.0£105.
4.2.13. (2E,4E)-5-(4-Hexyloxy-3-methoxyphenyl)-2-
methyl-penta-2,4-dienal (11(1)). Brown solid, mp 35–
39 8C, yield 71%. Anal. Calcd for C19H26O3 (302.41): H,
8.67; C, 75.46. Found: H, 8.7; C, 75.4. ESI-MS:
MHþ¼303.2. nmax (KBr) 3030, 2950, 2860, 1670, 1590,
1511, 1475, 1265, 1135, 990, 860, 789, 745, 650 cm21. dH
(300 MHz, CDCl3) 9.40 (1H, s, CHO), 6.90 (1H, d,
J¼10.8 Hz, CHvC(CH3)CHO), 6.81 (1H, dd, J¼8.9,
3.0 Hz, ArH), 6.79 (1H, dd, J¼14.7, 10.7 Hz, ArCHvCH),
6.76 (1H, d, J¼8.6 Hz, ArH), 6.70 (1H, d, J¼14.5 Hz,
ArCH), 6.65 (1H, d, J¼3.0 Hz), 3.97 (2H, t, J¼6.5 Hz,
CH2O), 3.89 (3H, s, OMe), 1.91 (3H, s, CMe), 1.30–1.79 (8H,
m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼354
nm, 1¼1.1£105.
4.2.10. (2E,4E,6E,8E,10E)-11-(4-Hexyloxy-3-methoxy-
phenyl)-2,6-dimethyl-undeca-2,4,6,8,10-pentaenal
(10(2)). Brown solid, mp 58–63 8C, yield 63%. Anal. Calcd
for C26H34O3 (394.55): C, 79.15; H, 8.69. Found: C, 78.9;
H, 8.8. ESI-MS: MHþ¼395.2. nmax (KBr) 2999, 2930,
2859, 1720, 1659, 1600, 1510, 1465, 1270, 1250, 1175,
1140, 1029, 969, 845, 645 cm21. dH (300 MHz, CDCl3)
9.40 (s, 1H, CHO), 6.90 (1H, d, J¼11.0 Hz, CHC(CH3)-
CHO), 6.82 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.79 (1H, dd,
J¼14.9, 9.8 Hz, ArCHvCH), 6.76 (1H, dd, J¼14.8,
10.1 Hz, ArCHvCH), 6.76 (d, 1H, J¼8.6 Hz, ArH), 6.71
4.2.14. (2E,4E,6E,8E)-9-(4-Hexyloxy-3-methoxyphenyl)-
2,6-dimethylnona-2,4,6,8-tetraenal (11(2)). Brown solid,

B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
1937
mp 50–54 8C, yield 65%. Anal. Calcd for C24H32O3
(368.51): H, 8.75; C, 78.22. Found: H, 8.80; C, 78.18.
ESI-MS: MHþ¼369.3. nmax (KBr) 3025, 2955, 2855, 1670,
1588, 1510, 1471, 1265, 1137, 991, 864, 791, 640 cm21. dH
(300 MHz, CDCl3) 9.41 (1H, s, CHO), 6.90 (1H, d, J¼
10.3 Hz, CHvC(CH3)CHO), 6.81 (1H, dd, J¼8.9, 3.0 Hz,
ArH), 6.79 (1H, dd, J¼10.1, 14.5 Hz, ArCHvCH), 6.76
(1H, d, J¼8.6 Hz, ArH), 6.79 (1H, dd, J¼14.0, 10.1 Hz,
ArCHvCH), 6.71 (1H, d, J¼14.8 Hz, ArCH), 6.65 (1H,
d, J¼2.98 Hz, ArH), 6.61 (1H, d, J¼10.2 Hz,
ArCHvCHCH), 6.30 (d, 1H, J¼14.3 Hz, C(Me)CH),
3.97 (2H, t, J¼6.6 Hz, CH2O), 3.89 (3H, s, OMe), 1.90
(6H, s, (CHvCHCHvC(Me))2), 1.30–1.79 (8H, m,
Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3) 410 nm,
1¼1.7£105.
4.2.18. (2E,4E,6E,8E)-9-(4-Hexyloxy-3-methoxyphenyl)-
2,4,6,8-tetramethylnona-2,4,6,8-tetraenal (12(2)). Brown
solid, yield 55%. Anal. Calcd for C26H36O3 (396.57): H,
9.15; C, 78.75. Found: H, 9.35; C, 78.62. ESI-MS:
MHþ¼397.3. nmax (KBr) 3010, 2985, 2933, 2860, 1668,
1625, 1510, 1460, 1340, 1255, 1140, 998 cm21. dH
(300 MHz, CDCl3) 9.41 (1H, s, CHO), 7.20 (1H, s,
CHvCMeCHO), 6.81 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.76
(1H, d, J¼8.6 Hz, ArH), 6.65 (1H, d, J¼3.0 Hz, ArH), 6.40
(1H, s, ArCH), 6.31(2H, s, (CHCMe)2), 3.97(2H, t,J¼6.5 Hz,
CH2O), 3.89 (3H, s, OMe), 1.91 (12H, s, CHvCMe)4), 1.30–
1.79 (8H, m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz).
4.2.19. (2E,4E,6E,8E,10E,12E)-13-(4-Hexyloxy-3-meth-
oxyphenyl)-2,4,6,8,10,12-hexamethyltrideca-2,4,6,8,
10,12-heksaenal (12(3)). Brown solid, yield 46%. Anal.
Calcd for C32H44O3 (476.70): H, 9.30; C, 80.63. Found: H,
9.55; C, 80.98. ESI-MS: MHþ¼477.3. nmax (KBr) 3025,
2965, 2935, 2857, 1670, 1596, 1511, 1468, 1360, 1254,
1240, 1175, 1150, 1010, 990, 855 cm21. dH (300 MHz,
CDCl3) 9.41 (1H, s, CHO), 7.20 (1H, s, CHvCMeCHO),
6.81 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.76 (1H, d, J¼8.6 Hz,
ArH), 6.65 (1H, d, J¼3.0 Hz, ArH), 6.40 (1H, s, ArCH),
6.30 (4H, s, (CHCMe)4), 3.97 (2H, t, J¼6.5 Hz, CH2O),
3.89 (3H, s, OMe), 1.91 (18H, s, (CHvCMe)6), 1.30–1.79
(8H, m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz).
4.2.15. (2E,4E,6E,8E,10E,12E)-13-(4-Hexyloxy-3-meth-
oxyphenyl)-2,6,10-trimethyl-trideca-2,4,6,8,10,12-hek-
saenal (11(3)). Brown solid, mp 69–73 8C, yield 58%.
Anal. Calcd for C29H38O3 (434.62): H, 8.81; C, 80.14.
Found: H, 8.9; C, 80.1. ESI-MS: MHþ¼435.3. nmax (KBr)
3022, 2960, 2920, 2870, 1668, 1588, 1509, 1470, 1264,
1137, 990, 862, 879, 740, 640 cm21. dH (300 MHz, CDCl3)
9.41 ((1H, s, CHO), 6.89 (1H, d, J¼10.2 Hz, CHvCMe-
CHO), 6.81, (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.79 (1H, dd,
J¼10.1, 14.0 Hz, ArCHvCH), 6.76 (1H, d, J¼8.6 Hz,
ArH), 6.70–6.73 (3H, m, (CHvCHCHCMe)2þArCH), 6.65
(1H, d, J¼3.0 Hz, ArH), 6.63 (2H, m, (CHvCHCHCMe)2),
6.61 (1H, d, J¼10.2 Hz, ArCHvCHCH), 6.30
(d, 1H, J¼9.8 Hz, (CHvCHCHCMe)2), 3.97 (2H, t, J¼
6.5 Hz, CH2O), 3.89 (3H, s, OMe), 1.90 (9H, s,
(CHvCHCHvC(Me))3), 1.30–1.79 (8H, m, Me(CH2)4),
0.90 (3H, t, J¼6.9 Hz). lmax(CHCl3)¼442 nm, 1¼2.1£105.
4.2.20. (2E,4E,6E,8E,10E,12E,14E,16E)-17-(4-Hexyloxy-
3-methoxyphenyl)-2,4,6,8,10,12,14,16-octamethylhepta-
deca-2,4,6,8,10,12,14,16-octaenal (12(4)). Brown solid,
yield 63%. Anal. Calcd for C38H52O3 (556.83): H, 9.41;
C, 81.97. Found: H, 9.7; C, 81.8. ESI-MS: MHþ¼557.4.
nmax (KBr) 3023, 2985, 2964, 2937, 2855, 1672, 1599,
1510, 1465, 1366, 1250, 1180, 1145, 1009, 995, 858 cm21
.
4.2.16. (2E,4E,6E,8E,10E,12E,14E,16E)-17-(4-Hexyloxy-
3-methoxyphenyl)-2,6,10,14-tetramethylheptadeca-
2,4,6,8,10,12,14,16-octaenal (11(4)). Brown solid, mp 87–
93 8C, yield 54%. Anal. Calcd for C34H44O3 (500.72): H,
8.86; C, 81.56. Found: H, 8.9; C, 81.5. ESI-MS: MHþ¼
501,3. nmax (KBr) 3025, 2955, 2950, 2860, 1672, 1587,
1510, 1472, 1265, 1140, 1125, 1030, 990, 860, 792,
742 cm21. dH (300 MHz, CDCl3) 9.41 (1H, s, CHO), 6.90
(1H, d, J¼10.2 Hz, CHvCMeCHO), 6.81, (1H, dd, J¼8.9,
3.0 Hz, ArH), 6.79 (1H, dd, J¼10.1, 14.0 Hz, ArCHvCH),
6.74–6.77 (4H, m, ArHþ(CHvCHCHCMe)3CHO),
6.71 (1H, d, J¼14.8 Hz, ArCH), 6.65 (1H, d, J¼3.0 Hz,
ArH), 6.63 (3H, m, (CHvCHCHCMe)3), 6.41 (3H, m,
(CHvCMeCHvCH)3), 3.97 (2H, t, J¼6.5 Hz, CH2O),
3.89 (3H, s, OMe), 1.90 (12H, s, (CHvCHCHvC(Me))4),
1.30–1.79 (8H, m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz).
dH (300 MHz, CDCl3) 9.41 (1H, s, CHO), 7.19 (1H, s,
CHvCMeCHO), 6.81 (1H, dd, J¼8.9, 3.0 Hz, ArH), 6.76
(1H, d, J¼8.6 Hz, ArH), 6.65 (1H, d, J¼3.0 Hz, ArH), 6.40
(1H, s, ArCH), 6.30 (6H, s, (CHCMe)6), 3.97 (2H, t,
J¼6.5 Hz, CH2O), 3.89 (3H, s, OMe), 1.91 (24H, s,
(CHvCMe)6), 1.30–1.79 (8H, m, Me(CH2)4), 0.90 (3H, t,
J¼6.9 Hz).
4.3. General procedure for the preparation of
symmetrical conjugated polyenals 13(n)–14(n)
Symmetrical conjugated polyenes 13(n)–14(n) were
obtained according to the procedure in Section 4.2 using
120 mmol of CH(OEt)3 (20 mL) in the first step and
22 mmol of template 2 and 72 mmol of appropriate ether 6
or 8 in the second step of synthesis.
l
max(CHCl3)¼458 nm, 1¼2.5£105.
4.3.1. 5-[2-Methoxy-5-methyl-3-(5-oxo-penta-1,3-dienyl)-
phenyl]-penta-2,4-dienal (13(2)). Brown solid, mp 42–
45 8C, yield 74%. Anal. Calcd for C18H18O3 (382.1): H,
6.43; C, 76.56. Found: H, 6.7; C, 76.2. ESI-MS: MHþ¼
383.3. nmax (KBr) 3010, 2973, 2930, 1689, 1475, 1470,
1396, 1234, 1095, 1002, 877 cm21. dH (300 MHz, CDCl3)
9.50 (2H, d, J¼8.0 Hz, 2£CHO), 7.8 (2H, s, HArH), 7.25
(2H, dd, J¼14.8, 10.6 Hz, 2£CHvCHCHO), 6.93 (2H, d,
J¼15.2 Hz, HCArCH), 6.79 (2H, dd, J¼10.4, 15.1 Hz,
2£CHvCH), 6.2 (2H, dd, J¼8.1, 14.8 Hz, 2£CHCHO),
4.01 (3H, s, OCH3), 2.40 (3H, s, ArMe). lmax(CHCl3)¼316
nm, 1¼1.3£105.
4.2.17. (2E,4E)-5-(4-Hexyloxy-3-methoxyphenyl)-2,4-
dimethyl-penta-2,4-dienal (12(1)). Brown solid, yield
62%. Anal. Calcd for C20H28O3 (316.44): H, 8.92; C,
75.91. Found: H, 9.0; C, 75.7. ESI-MS: MHþ¼317.3. nmax
(KBr) 2980, 2930, 2850, 1668, 1637, 1510, 1466, 1377,
1253, 1135, 999 cm21. dH (300 MHz, CDCl3) 9.40 (1H, s,
CHO), 7.23 (1H, s, CHvCMeCHO), 6.81, (1H, dd, J¼8.9,
3.0 Hz, ArH), 6.76 (1H, d, J¼8.6 Hz, ArH), 6.65 (1H, d,
J¼3.0 Hz, ArH), 6.39 (1H, s, ArCH), 3.97 (2H, t, J¼6.5 Hz,
CH2O), 3.89 (3H, s, OMe), 1.90 (6H, s, CHvCMe)2), 1.30–
1.79 (8H, m, Me(CH2)4), 0.90 (3H, t, J¼6.9 Hz).

1938
B. W. Domagalska et al. / Tetrahedron 60 (2004) 1931–1939
4.3.2. 9-[2-Methoxy-5-methyl-3-(9-oxo-nona-1,3,5,7-
teraenyl)-phenyl]-nona-2,4,6,8-tetraenal (13(4)). Brown
solid, yield 51%. Anal. Calcd for C26H26O3 (386.19): H,
6.79; C, 80.79. Found: H, 7.0; C, 80.5. ESI-MS: MHþ¼
387.5. nmax (KBr) 3025, 2970, 2932, 1690, 1472, 1470,
1400, 1235, 1170, 1002, 875 cm21. dH (300 MHz, CDCl3)
9.51 (2H, d, J¼8.1 Hz, 2£CHO), 7.8 (2H, s, HArH), 7.18
(2H, dd, J¼15.1, 11.3 Hz, 2£CHvCHCHO), 6.93 (2H, d,
J¼15.0 Hz, HCArCH), 6.79 (2H, dd, J¼15.2, 10.8 Hz,
2£CHvCH), 6.45–6.70 (8H, m, 2£(CHvCH)2), 6.1 (2H,
dd, J¼8.1, 15.0 Hz, 2£CHCHO), 3.90 (3H, s, OCH3), 2.40
(3H, s, ArMe). lmax(CHCl3)¼362 nm, 1¼2.2£105.
solid, mp 135–139 8C, yield 41%. Anal. Calcd for
C36H36O6 (564.2): H, 6.43; C, 76.56. Found: H, 6.5; C,
76.4. ESI-MS: MHþ¼565.7. nmax (KBr) 2980, 2935, 2850,
1860, 1688, 1626, 1590, 1475, 1399, 1235, 1100, 1025, 880,
640 cm21. dH (300 MHz, CDCl3) 9.51 (3H, d, J¼8.1 Hz,
3£CHO), 7.18 (3H, dd, J¼15.1, 11.3 Hz, 3£
CHvCHCHO), 6.92 (3H, d, J¼15.0 Hz, Ar(CH)3), 6.80
(3H, dd, J¼10.8, 15.2 Hz, 3£CHvCH), 6.45–6.70
(m, 12H), 6.1 (3H, dd, J¼8.1, 15.0 Hz, 3£CHCHO), 3.90
(9H, s, 3£OCH3).
4.4.3. 2-Methyl-5-[2,4,6-trimethoxy-3,5-bis-(4-methyl-5-
oxo-penta-1,3-dienyl)-phenyl]-penta-2,4-dienal (16(1)).
Brown solid, yield 67%. Anal. Calcd for C27H30O6
(450.2): H, 6.72; C, 71.97. Found: H, 6.9; C, 71.8. ESI-
MS: MHþ¼451.5. nmax (KBr) 2935, 2890, 1850, 1670,
1630, 1510, 1472, 1380, 1240, 1135, 889, 645 cm21. dH
(300 MHz, CDCl3) 9.50 (3H, s, 3£CHO), 6.90 (3H, d,
J¼10.8 Hz, 3£CHvCMe), 6.79 (3H, dd, J¼10.7, 14.7 Hz,
CHvCH), 6.70 (3H, d, J¼14.5 Hz, Ar(CH)3), 4.01 (9H,
s, 3£OCH3), 1.91 (9H, s, 3£CMe). lmax(CHCl3)¼324 nm,
1¼1.9£105.
4.3.3. 5-[2-Methoxy-5-methyl-3-(4-methyl-5-oxo-penta-
1,3-dienyl)-phenyl]-2-methyl-penta-2,4-dienal (14(1)).
Brown solid, yield 72%. Anal. Calcd for C20H22O3
(310.39): H, 7.14; C, 77.39. Found: H, 7.3; C, 77.4. ESI-
MS: MHþ¼311.1. nmax (KBr) 3030, 2970, 2861, 2756, 1690,
1477, 1396, 1235, 1170, 1090, 870 cm21. dH (300 MHz,
CDCl3) 9.41 (2H, s, 2£CHO), 7.8 (2H, s, HArH), 6.91 (2H, d,
J¼10.5 Hz, CHvCMeCHO), 6.75 (2H, dd, J¼10.5, 14.5 Hz,
HCvHCArCHvCH), 6.71 (2H, d, J¼13.5 Hz, HCArCH),
3.90 (3H, s, OCH3), 2.40 (3H, s, ArMe), 1.90 (6H, s,
2£CMeCHO). lmax(CHCl3)¼337 nm, 1¼1.5£105.
4.4.4. 9-[3,5-Bis-(4,8-dimethyl-9-oxo-nona-1,3,5,7-tetra-
enyl)-2,4,6-trimethoxy-phenyl]-2,6-dimethyl-nona-2,4,
6,8-tetraenal 16(2). Brown solid, yield 40%. Anal. Calcd
for C42H48O6 (648.3): H, 7.46; C, 77.74. Found: H, 7.6; C,
77.6. ESI-MS: MHþ¼649.8. nmax (KBr) 3020, 2940, 2839,
1680, 1580, 1476, 1390, 1310, 1230, 1170, 1015, 798,
650 cm21. dH (300 MHz, CDCl3) 9.44 (3H, s, 3£CHO),
6.90 (3H, d, J¼10.2 Hz, 3£CHvCMe), 6.79 (3H, dd,
J¼10.1, 14.5 Hz, 3£CHvCH), 6.76 (3H, dd, J¼14.1,
10.2 Hz, 3£CHCHvC(Me)CHO), 6.71 (3H, d, J¼14.8 Hz,
Ar(CH)3), 6.61 (3H, d, J¼10.2 Hz, 3£CHvCHMe), 6.30
(3H, d, J¼14.3 Hz, MeCvCH), 4.01 (9H, s, 3£OCH3), 1.90
(18H, s, 6£CMe).
4.3.4. 9-[3-(4,8-Dimethyl-9-oxo-nona-1,3,5,7-tetraenyl)-
2-methoxy-5-methyl-phenyl]-2,6-dimethyl-nona-2,4,6,8-
tetraenal (14(2)). Brown solid, yield 49%. Anal. Calcd for
C30H34O3 (442.60): H, 7.74; C, 81.41. Found: H, 7.88; C,
81.12. ESI-MS: MHþ¼443.2. nmax (KBr) 2975, 2932, 2856,
1690, 1625, 1475, 1470, 1396, 1233, 1100, 875 cm21. dH
(300 MHz, CDCl3) 9.41 (2H, s, 2£CHO), 7.60 (2H, s,
HArH), 6.90 (2H, d, J¼10.0 Hz, CHvCMeCHO), 6.79
(2H, dd, J¼10.5, 14.5 Hz, HCvHCArCHvCH), 6.76
(2H, dd, J¼14.1, 10.1 Hz, 2£CHCHvC(Me)CHO), 6.71
(2H, d, J¼14.8 Hz, HCArCH), 6.61 (2H, d, J¼10.2 Hz,
HCHCvHCArCHvCHCH), 6.30 (2H, d, J¼14.3 Hz,
2£CMeCH), 3.90 (3H, s, OCH3), 2.40 (3H, s, ArMe), 1.90
(12H, s, 4£CMe). lmax(CHCl3)¼382 nm, 1¼2.5£105.
Acknowledgements
4.4. General procedure for the preparation of
symmetrical conjugated polyenals 15(n), 16(n)
Supports of this work by the State Committee of Scientific
Research (Grant No. 7 T09A 063 20) and the Faculty of
Chemistry (Wrocl⁄aw University of Technology) are grate-
fully acknowledged. We thank the Laboratory of Materials
Science (Institute of Physical and Theoretical Chemistry,
Wrocl⁄aw University of Technology) for the use of their
FT-IR Nexus (Thermo Nicolet) and UV–Vis Unicam
(Thermo Spectronic) spectrophotometers.
Octupolar conjugated polyenes were obtained according
to procedure described in Section 4.2 using 180 mmol of
CH(OEt)3 (30 mL) to acetalization reaction and 22 mmol of
template 3 and 108 mmol of appropriate ether 6 or 8 in the
second step of reaction.
4.4.1. 5-[2,4,6-Trimethoxy-3,5-bis-(5-oxo-penta-1,3-die-
nyl)-phenyl]-penta-2,4-dienal (15(2)). Brown solid, mp
98–102 8C, yield 69%. Anal. Calcd for C24H24O6 (408.15):
H, 5.93; C, 70.56. Found: H, 6.0; C, 70.5. ESI-MS: MHþ¼
409.1. nmax (KBr) 3029, 2954, 2856, 1705, 1637, 1510,
1467, 1132, 975, 870 cm21. dH (300 MHz, CDCl3) 9.50
(3H, d, J¼8.0 Hz, 3£CHO), 7.19 (3H, dd, J¼14.8, 10.6 Hz,
3£CHvCHCHO), 6.93 (3H, d, J¼15.2 Hz, Ar(CH)3), 6.79
(3H, dd, J¼10.4, 15.1 Hz, 3£CHvCH), 6.2 (3H, dd, J¼8.1,
14.8 Hz, 3£CHCHO), 4.03 (9H, s, 3£OCH3). lmax(CHCl3)
331 nm, 1¼3.4£105.
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