E. Karpuk, D. Schollmeyer, H. Meier
FULL PAPER
1H NMR (CDCl3): δ = 2.74 (s, 3 H, CH3), 3.90 (s, 6 H, p-OCH3),
3.93 (s, 12 H, m-OCH3), 6.89 (s, 4 H, o-H, trimethoxyphenyl), 7.48/
7.81 (AB, 3J = 15.6 Hz, 4 H, olefin. H), 8.66 (“s”, 2 H, o-H,
phenyl), 8.76 (“s”, 1 H, p-H, phenyl) ppm. 13C NMR (CDCl3): δ
= 27.0 (CH3), 56.4 (m-OCH3), 61.1 (p-OCH3), 106.2 (o-CH, tri-
methoxyphenyl), 120.0 (C-2), 129.8 (i-C, trimethoxyphenyl), 131.6,
132.1 (CH, phenyl), 137.8, 139.1 (Cq, phenyl), 141.1 (p-CqO), 146.8
(C-3), 153.6 (m-CqO), 188.9 (C-1), 197.1 (CO, acetyl) ppm. FD
MS: m/z (%) = 561 (100) [M + H+] C32H32O9 (560.2): calcd. C
68.56, H 5.75; found C 68.45, H 5.89.
to-head cycloaddition 13 Ǟ 14, the intramolecular mobility
is too low and the distance between the remaining double
bonds too large to permit further intramolecular [2π+2π]
photocycloadditions.
The crystalline states of 7a and 13a are capable of ef-
ficient single syn-head-to-tail cycloadditions – even when
the distance between the olefinic double bonds in neigh-
boring molecules exceeds with 5.07 Å by far the value of
4.2 Å proposed in Schmidt’s rule. We explain this result by
the fact, that the planes of the C=C double bonds are paral-
lel and have a short distance of 1.46 Å, which permits a
sufficient overlap of the π- and the π*-orbitals.
(E)-1-{3,5-Bis[(E)-3-(3,4,5-trimethoxyphenyl)acryloyl]phenyl}-3-
(3,4,5-trimethoxyphenyl)propenone (7b): Yellowish solid, m.p.
1
208 °C. H NMR (CDCl3): δ = 3.91 (s, 9 H, p-OCH3), 3.94 (s, 18
3
H, m-OCH3), 6.91 (s, 6 H, o-H, trimethoxyphenyl), 7.52 (d, J =
15.4 Hz, 3 H, olefin. H), 7.84 (d, 3J = 15.4 Hz, 3 H, olefin. H),
8.83 (s, 3 H, aromat. H, central benzene ring) ppm. 13C NMR
(CDCl3): δ = 56.4 (m-OCH3), 61.0 (p-OCH3), 106.2 (o-CH, tri-
methoxyphenyl), 120.2, 146.8 (olefin. CH), 129.8 (i-C, trimethoxy-
phenyl), 131.7 (aromat. CH, central benzene ring), 139.2 (Cq, cen-
tral benzene ring), 141.1 (p-CqO), 153.6 (m-CqO), 189.0 (CO) ppm.
FD MS: m/z (%) = 739 (100) [M + H+]. HR MS: calcd. for
[C42H42O12 + Na+] 761.2574; found 761.2468.
Experimental Section
General Remarks: UV/Vis: Zeiss MCS 320/340, CH2Cl2 as solvent.
1H and 13C NMR: Bruker AMX 400, CDCl3/TMS as internal stan-
dard. MS: Finnigan MAT 95 (FD, accelerating voltage 5 kV),
Micromass QTOF Ultima-3 (ESI, reference: CsI/NaI standard
solution), DSC: Perkin–Elmer DSC7. Melting points: Stuart Scien-
tific SMP/3; values uncorrected.
(E)-1-{3,5-Bis[(E)-3-(3,4,5-trihexyloxyphenyl)acryloyl]phenyl}-3-
(3,4,5-trihexoxyphenyl)propenone (7c): Preparation analogous to 7a.
After 1 d of stirring in the dark, the solution was neutralized with
HCl and extracted with CH2Cl2. The organic layer was washed
with saturated aqueous NaCl solution and H2O, dried with
MgSO4, and the solvents were evaporated. Column chromatog-
raphy (3ϫ40 cm SiO2; gradient toluene/ethyl acetate, 10:0 to 10:1)
yielded 268 mg (18%) of a yellowish solid which showed a single
phase transition in the DSC at 169.0 °C (onset temperature, heating
(E)-1-{3,5-Bis[(E)-(3-phenylacryloyl)]phenyl}-3-phenylpropenone [all-
(E)-1,3,5-Tricinnamoylbenzene (7a)]: Preparation according to the
1
literature,[10,11] yield 1.8 g (70%), m.p. 179 °C. H NMR (CDCl3):
3
δ = 7.45 (m, 9 H, m-H, p-H, phenyl), 7.65 (d, J = 15.6 Hz, 3 H,
2-H), 7.70 (m, 6 H, o-H, phenyl), 7.93 (d, 3J = 15.6 Hz, 3 H, 3-H),
8.84 (s, 3 H, aromat. H, central benzene ring) ppm. 13C NMR
(CDCl3): δ = 121.1 (C-2), 128.8, 129.1 (o-, m-CH, phenyl), 131.1,
131.8 (aromat. CH, p-C, phenyl and central benzene ring), 134.5
(i-C, phenyl), 139.1 (Cq, central benzene ring), 146.4 (C-3), 188.9
(C-1) ppm. FD MS: m/z (%) = 469 (100) [M + H+]. HR MS: calcd.
1
curve with a rate of 10 °Cmin–1. H NMR (CDCl3): δ = 0.90 (m,
27 H, CH3), 1.33–1.40 (m, 54 H, CH2) 1.77 (m, 18 H, CH2), 4.00
for C33H34O3 468.1725; found 468.1708. UV/Vis (CH2Cl2): λmax
=
(m, 18 H, OCH2), 6.90 (s, 6 H, o-H, trihexyloxyphenyl), 7.49 (d, 3J
326 nm; εmax = 69040 cm mmol–1.
3
= 15.6 Hz, 3 H, 2-H), 7.88 (d, J = 15.6 Hz, 3 H, 3-H), 8.77 (s, 3
H, aromat. H, central benzene ring) ppm. 13C NMR (CDCl3): δ =
13.0, 13.0 (CH3), 21.8, 25.0, 28.6, 29.6, 31.0 (CH2, partly superim-
posed) 68.5 (m-OCH2), 72.8 (p-OCH2), 106.5 (o-CH, trihexyloxy-
phenyl), 119.6, 145.8 (olefin. CH), 128.8 (i-C, trihexyloxyphenyl),
130.6 (aromat. CH, central benzene ring), 138.7 (Cq, central ben-
zene ring), 140.4 (p-CqO), 152.7 (m-CqO), 188.4 (CO) ppm. FD
MS: m/z (%) = 1369 (100) [M+·]. HR MS (ESI): calcd. for
[C87H132O12 + Na+] 1391.9617; found 1391.9585. UV/Vis
(CH2Cl2): λmax = 365 nm; εmax = 64905 cm mmol–1.
Condensation Reaction of 1,3,5-Triacetylbenzene (5) with 3,4,5-Tri-
methoxybenzaldehyde (6b): Ketone 5 (0.57 g, 2.8 mmol) and NaOH
(128 mg, 3.2 mmol) were warmed in C2H5OH (40 mL)/H2O
(60 mL) to 40 °C before aldehyde 6b (2.74 g, 14.0 mmol), dissolved
in C2H5OH (20 mL), was slowly added. The colorless solution
turned orange-red and a solid precipitated. After 5 h of stirring at
40 °C, CHCl3 was added so that the precipitate was dissolved. The
organic layer was washed with the same amount of H2O and satu-
rated aqueous NaCl solution, dried with MgSO4, and the solvents
were evaporated. Column chromatography (3ϫ50 cm SiO2; tolu-
ene/ethyl acetate, 9:1) yielded excess 6b, 264 mg (25%) of monocon-
densation product, 306 mg (20%) of dicondensation product and
71 mg (3%) of tricondensation product 7b.
(E)-1-{3,5-Bis[(E)-3-(3,4,5-tridodecyloxyphenyl)acryloyl]phenyl}-3-
(3,4,5-tridodecyloxyphenyl)propenone (7d): Preparation and workup
as described for 7c. Yield 354 mg (30%) of a yellowish waxy solid,
which showed in the DSC a transition to the isotropic phase at
123.7 °C (onset temperature, 2nd heating curve, rate: 10 °Cmin–1).
The 2nd heating curve contains two further overlapping peaks with
maxima at 20 and 27 °C which might point to an LC phase. 1H
NMR (CDCl3): δ = 0.85 (m, 27 H, CH3), 1.24–1.46 (m, 162 H,
CH2) 1.78 (m, 18 H, CH2), 4.00 (m, 18 H, OCH2), 6.87 (s, 6 H, o-
H, tridodecyloxyphenyl), 7.46 (d, 3J = 15.2 Hz, 3 H, 2-H), 7.80 (d,
3J = 15.2 Hz, 3 H, 3-H), 8.80 (s, 3 H, aromat. H, central benzene
ring) ppm. 13C NMR (CDCl3): δ = 14.1, 14.1 (CH3), 22.7, 26.1,
29.7, 29.7, 32.0 (CH2, partly superimposed) 69.4 (m-OCH2), 73.7
(p-OCH2), 107.6 (o-CH, tridodecyloxyphenyl), 119.9, 147.2 (olefin.
CH), 126.9 (i-C, tridodecyloxyphenyl), 129.4 (aromat. CH, phenyl),
139.4 (Cq, central benzene ring), 141.5 (p-CqO), 153.5 (m-CqO),
(E)-1-(3,5-Diacetylphenyl)-3-(3,4,5-trimethoxyphenyl)propenone:
1
Yellowish solid, m.p. 154 °C. H NMR (CDCl3): δ = 2.71 (s, 6 H,
CH3), 3.89 (s, 3 H, p-OCH3), 3.91 (s, 6 H, m-OCH3), 6.88 (s, 2 H,
o-H, trimethoxyphenyl), 7.43/7.79 (AB, 3J = 15.6 Hz, olefin. H),
8.69 (“s”, 1 H, p-H, phenyl), 8.70 (“s”, 2 H, o-H, phenyl) ppm. 13
C
NMR (CDCl3): δ = 26.9 (CH3), 56.4 (m-OCH3), 61.0 (p-OCH3),
106.2 (o-CH, trimethoxyphenyl), 120.0 (C-2), 129.8 (i-C, trimeth-
oxyphenyl), 131.4 (p-CH, phenyl), 131.9 (o-CH, phenyl), 141.1 (p-
CqO, trimethoxyphenyl), 146.8 (C-3), 153.6 (m-CqO, trimethoxy-
phenyl), 188.7 (C-1), 196.8 (CO, acetyl) ppm. FD MS: m/z (%) =
383 (100) [M + H+]. C22H22O6 (382.1): calcd. C 69.10, H 5.80;
found C 69.45, H 5.86.
(E)-1-{3-Acetyl-5-[(E)-3-(3,4,5-trimethoxyphenyl)acryloyl]phenyl}-3- 189.3 (CO) ppm. FD MS: m/z (%) = 2127 (100) [M+·]. HR MS
(3,4,5-trimethoxyphenyl)propenone: Yellowish solid, m.p. 134 °C.
(ESI): calcd. for [C141H240O12 + Na+] 2148.8068; found 2148.7986.
1988
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