Synthesis of highly substituted hexahelicenes

Article abstract of DOI:10.1002/hlca.201300187

C₂-Symmetric hexahelicenes 3a-3g, which bear four or six alkoxy chains, were prepared in eight-to-nine reaction steps in high overall yields. The final step consisted of a twofold oxidative photocyclization of the corresponding 2,7-bis(2-phenylethenyl)naphthalenes. Long (and branched) chains provide a good solubility and processability, which is a prerequisite for applications in organic synthesis and materials science.

Full text of DOI:10.1002/hlca.201300187

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Helvetica Chimica Acta – Vol. 96 (2013)
Synthesis of Highly Substituted Hexahelicenes
by Manfred Schwertel, Sabine Hillmann, and Herbert Meier*
Institute of Organic Chemistry, University of Mainz, Duesbergweg 10 – 14, DE-55099 Mainz
(
phone: þ 49-6131-3922605; fax: þ 49-6131-3925396; e-mail: hmeier@uni-mainz.de)
C -Symmetric hexahelicenes 3a – 3g, which bear four or six alkoxy chains, were prepared in eight-to-
2
nine reaction steps in high overall yields. The final step consisted of a twofold oxidative photocyclization
of the corresponding 2,7-bis(2-phenylethenyl)naphthalenes. Long (and branched) chains provide a good
solubility and processability, which is a prerequisite for applications in organic synthesis and materials
science.
1. Introduction. – Since their first preparation, helicenes attracted remarkable
attention due to their outstanding properties [1 – 9]. In the previous years, an increasing
number of applications of helicenes was reported; for example, in catalytic processes
[
10 – 17] or in materials science such as nonlinear optics (NLO) [18][19], molecular
machines [20], liquid crystals [21][22], and thin-film transistors [23]. The majority of
the here referred articles deals with carbo- or heterocyclic hexahelicenes. This
prompted us to report our work on highly substituted hexahelicenes.
Photochemical generations of hexahelicenes (3), in the sense of twofold oxidative
cyclizations, start either from 2,7-bis(2-phenylethenyl)naphthalenes (1) or from 2-{2-[4-
(2-phenylethenyl)phenyl]ethenyl}naphthalene (2). The electrocyclic ring closures with
subsequent dehydrogenation furnish good yields of these sterically hindered, chiral,
benzenoid aromatics 3 (Scheme 1). In principle, 1 and 2 have more than one cyclization
Scheme 1. Photochemical Routes to Hexahelicenes
ꢀ
2013 Verlag Helvetica Chimica Acta AG, Zꢁrich

Helvetica Chimica Acta – Vol. 96 (2013)
2021
route; however, according to theoretical predictions, the alternative routes play a minor
role [24][25]. We applied the process 1 ! 3 for the formation of highly substituted
hexahelicenes 3, which have a C axis of symmetry. To achieve good solubilities, we
2
introduced preferentially long and/or branched alkoxy groups. A certain background of
this study was the question: ꢂDo such compounds form liquid crystals, or can such
components change the mesophase properties of known discotic systems.ꢃ
2
. Results and Discussion. – We started the synthetic route 1 ! 3 with naphthalene-
2
,7-diol (4) and introduced first Br-substituents at C(3) and C(6) (Scheme 2). The use
of excess Br led to the 1,3,6,8-tetrabromo derivative, from which the present Sn
2
powder removed the Br-substituents at C(1) and C(8) [26]. Three slightly different
methods were then applied for the twofold O-alkylation 5 ! 6a – 6e. Phase-transfer
catalysis is particularly recommended for longer and/or branched alkyl groups. The
dialdehydes 7a – 7e were obtained by twofold Bouveault reactions.
Scheme 2. Preparation of 3,6-Dialkoxynaphthalene-2,7-dicarbaldehydes 7a – 7e
i) Br , Sn, AcOH. ii) KOH, Me SO . iii) RBr, KOH, Aliquat 336, 1,4-dioxane. iv) RꢀTs, K CO , Aliquat
2
2
4
2
3
336, 1,4-dioxane. v) BuLi, THF/DMF.
In addition to the carbonyl components 7a – 7e, phosphonium salts for Wittig
reactions or phosphonates for WittigꢀHorner reactions were required. Salicylaldehyde
8
was alkylated to 9a – 9c for this purpose. Reduction with LiAlH led to the benzyl
4
alcohols 10a – 10c, which were directly transformed to the phosphonium bromides
1a – 11c, respectively, by the reaction with Ph P · HBr. All these processes gave
1
3
excellent-to-quantitative yields (Scheme 3).
-Methylphenol (12a) and 3-methylcatechol (12b) were transformed to the ethers
3a – 13c. Bromination with N-bromosuccinimide (NBS) gave the corresponding
2
1
benzyl bromides, which were in situ reacted with (EtO) P. Arbusov rearrangements
3
yielded the phosphonates 14a – 14c.

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Helvetica Chimica Acta – Vol. 96 (2013)
Scheme 3. Preparation of the Phosphonium Salts 11a – 11c and the Phosphonates 14a – 14c
Wittig olefinations of 7a, 7d, 7e, and 11a – 11c, and WittigꢀHorner reactions of 7b,
c, 7e, and 14a – 14c led then to the 2,7-bis(2-phenylethenyl)naphthalenes 1a – 1g
7
(
Scheme 4). The generated double bonds had (E)-configurations in the case of the
WittigꢀHorner reactions. The Wittig reactions, however, yielded all three stereoisomers
Z,E)-1, (E,E)-1, and a small amount of (Z,Z)-1. The subsequent photocyclization 1 !
required (Z)-configurations, which were formed in any case by irradiation in the
(
3
excited singlet state S . Therefore, stereoisomer mixtures of 1 could be directly used.
1
The oxidation with I was sustained by the addition of methyloxirane, which captured
2
the formed HI [27][28]. The hexahelicenes 3a – 3g were obtained as racemic mixtures
1
of (þ)-(P)- and (ꢀ)-(M)-isomers. )
The new compounds were characterized by 1D- and 2D-NMR spectroscopy. The
data of the target compounds 3a – 3g are compiled in Tables 1 and 2. The hexahelicenes
3
a – 3g belong to the point group C . Their CH groups contain diastereotopic H-atoms.
2 2
Different signals are particularly visible for the CH O H-atoms.
2
All hexahelicenes 3a – 3g have a good solubility in CHCl and many other organic
3
solvents such as THF or acetone. An exception is the tetramethoxy derivative 3a, the
13
solubility of which was not sufficient for recording a highly resolved C-NMR
spectrum. The Figure shows the differential scanning calorimetry (DSC) measure-
ments of the tetrakis- and hexakis(dodecyloxy) compounds 3b and 3f, respectively.
Both compounds form more than one crystalline but no thermotropic liquid crystalline
phase. Moreover, 3b exhibits an enormous undercooling effect for the crystalliza-
tion.
1)
Commercially available.

Helvetica Chimica Acta – Vol. 96 (2013)
2023
Scheme 4. Preparation of the 2,7-Bis(2-phenylethenyl)naphthalenes 1a – 1g and the Hexahelicenes 3a – 3g
i) BuLi, THF. ii) BuLi, THF, or alternatively NaH, dimethoxyethane.
3
. Conclusions. ꢀ Hexahelicenes 3a – 3g with four or six alkoxy groups could be
prepared by twofold oxidative cyclization of the corresponding 2,7-bis(2-phenyl-
ethenyl)naphthalenes 1a – 1g, which were synthesized by Wittig or WittigꢀHorner
reactions. Starting from commercially available compounds, altogether eight to nine
steps were needed to obtain the C -symmetric hexahelicenes in high yields. The
2
tetrakis(dodecyloxy) compound 3b, for example, was obtained in eight steps in an
average yield of 79% for each step. Long and/or branched alkoxy chains render the
compounds a good solubility, which is a prerequisite for several applications in organic
synthesis and materials science. The melting points of 3a – 3f range from þ 2188 to
ꢀ
88; 3g is an oil which forms a glassy state at ꢀ 508. None of the alkoxyhexahelicenes
generates a liquid-crystalline phase. Further studies shall reveal whether known
discotic mesophases can be transformed to chiral mesophases by doping with these
alkoxyhexahelicenes.
We are grateful to the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie for
financial support.

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Helvetica Chimica Acta – Vol. 96 (2013)

Helvetica Chimica Acta – Vol. 96 (2013)
2025
Table 2. 13C-NMR Data of the Hexahelicenes 3b – 3g. Recorded in CDCl ; d in ppm.
3
arom. CH
Cq
C O
CH O
CH
CH2a)
Mea)
14.1
q
2
3
b
c
104.0, 105.3,
114.8, 123.4,
123.7, 129.8,
131.1, 134.7
153.9, 154.4
154.2, 154.7
154.0, 154.5
68.4, 68.5
70.9, 70.9
71.1, 71.1
22.7, 26.3,
26.4, 29.4,
29.5, 29.7,
1
1
18.9, 119.7,
20.9, 124.1
3
1.9
3
104.0, 105.3,
114.9, 123.6,
123.9, 130.2,
131.2, 134.8
39.8
38.2
23.1, 24.3,
24.4, 29.2,
29.3, 29.7,
11.3, 14.1
1
1
19.0, 119.8,
20.9, 124.2
3
0.9, 31.0
3
d
e
103.8, 105.1,
114.7, 123.4,
123.7, 129.8,
131.0, 134.7
114.0, 122.0,
124.9, 127.9,
130.0, 135.0
23.0, 29.2,
29.6, 31.4
14.0
14.1
1
1
18.8, 119.7,
20.7, 124.0
3
103.3, 113.0,
141.7, 147.7,
153.9
68.4, 69.2,
73.6
22.7, 25.9,
26.0, 29.4,
29.5, 30.4,
1
1
13.0, 119.5,
19.9
3
1.6, 31.9
3
3
f
103.3, 113.0,
114.0, 122.0,
124.9, 127.9,
130.0, 135.0
141.7, 147.7,
153.9
68.4, 69.2,
73.7
22.7, 26.2,
26.3, 29.4,
29.5, 29.7,
14.1
14.1
1
1
13.0, 119.5,
20.0
3
1.9
g
103.2, 113.1,
114.0, 122.2,
125.0, 128.0,
130.1, 135.1
141.7, 147.8,
154.1
69.2, 71.1,
73.7
38.2
22.7, 23.1,
26.0, 29.3,
29.4, 29.7,
1
1
13.1, 119.5,
20.0
3
1.6, 32.0
a) Superimposed signals.
Experimental Part
General. M.p.: Bꢀchi melting-point apparatus. Differential scanning calorimetry (DSC): DSC-7
1
13
from Perkin-Elmer, heating and cooling curves with a rate of 108/min. H- and C-NMR spectra: AM-
00 spectrometer from Bruker; CDCl as solvent if not otherwise stated, Me Si as internal standard; d in
4
3
4
ppm and J in Hz. FD-MS: Finnigan-MAT-95 spectrometer, 5-kV ionization voltage. EI-MS: Finnigan-
MAT-95, 70-eV ionization energy.
3
,6-Dibromonaphthalene-2,7-diol (5). Preparation according to [29]. Yield: 67% ([29]: 70%). M.p.
898 ([26]: m.p. 189 – 1908).
,7-Dibromo-3,6-dimethoxynaphthalene (6a). To 5 (10.0 g, 31.4 mmol) in 44 ml of 10% KOH
78.5 mmol), Me SO (7.9 g, 62.6 mmol) was slowly dropped under N . The temp. should thereby not
1
2
(
2
4
2
exceed 408. The mixture was then heated for 45 min to ca. 1008, cooled, and extracted with 100 ml of
Et O. The org. phase was washed with dil. KOH and H O, dried (MgSO ), and evaporated. The residue
2
2
4
1
was recrystallized from EtOH. Yield: 8.74 g (80%). M.p. 1778 ([26]: m.p. 176.5 – 1778). H-NMR
(
CDCl ): 3.95 (s, 2 MeO); 7.02 (s, HꢀC(4), HꢀC(5)); 7.83 (s, HꢀC(1), HꢀC(8)). The compound was
3
identical to an authentic sample [26].
2,7-Dibromo-3,6-bis(hexyloxy)naphthalene (6b). To a soln. of KOH (6.6 g, 0.12 mol), Aliquat 336
(
1.0 g), and 5 (15.0 g, 43 mmol) in 100 ml of dioxane, 1-bromohexane (21.5 g, 130 mmol) was dropped.
The mixture was heated to 908 for 24 h, cooled, and filtered. The solvent was evaporated, and the residue
was purified by column filtration (SiO (6 ꢁ 30 cm); CH Cl ). Yield: 16.1 g (77%). Colorless solid. M.p.
2
2
2
1
7
0 – 728. H-NMR (CDCl ): 0.85 – 0.95 (m, J ¼ 6.2, 2 Me); 1.30 – 1.40 (m, 4 CH ); 1.40 – 1.60 (m, 2 CH );
3
2
2
3
1
.82 – 1.95 (m, 2 CH ); 4.06 (t, J ¼ 6.5, 2 CH O); 6.97 (s, HꢀC(4), HꢀC(5)); 7.83 (s, HꢀC(1), HꢀC(8)).
2
2
13
C-NMR (CDCl ): 14.0 (Me); 22.6, 25.7, 28.9, 31.5 (CH ); 69.1 (OCH ); 106.4 (C(4), C(5)); 111.8 (C(2),
3
2
2

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Helvetica Chimica Acta – Vol. 96 (2013)
Figure. DSC Heating and cooling curves of 3b and 3f, measured with a rate of 10 K minꢀ1. Onset
ꢀ1
temperatures in 8 and phase transition enthalpies DH in kJ mol
C(7)); 125.0 (C(8a)); 130.8 (C(1), C(8)); 133.9 (C(4a)); 153.7 (C(3), C(6)). The compound was identical
to an authentic sample [30].
2
,7-Dibromo-3,6-bis(dodecyloxy)naphthalene (6c). Prepared as described for 6b. Yield: 73%.
1
Colorless solid. M.p. 638. H-NMR (CDCl ): 0.81 – 0.91 (m, 2 Me); 1.20 – 1.24 (m, 18 CH ); 1.40 – 1.55 (m,
3
2
3
2
CH ); 1.81 – 1.93 (m, 2 CH ); 4.05 (t, J ¼ 6.5, 2 CH O); 6.96 (s, HꢀC(4), HꢀC(5)); 7.83 (s, HꢀC(1),
2
2
2
13
HꢀC(8)). C-NMR (CDCl ): 14.1 (Me); 22.7, 26.0 29.0, 29.3, 29.6, 31.3 (CH , partly superimposed); 69.1
3
2
(
(
8
CH O); 106.4 (C(4), C(5)); 111.8 (C(2), C(7)), 125.0 (C(8a)); 130.8 (C(1), C(8)); 133.9 (C(4a)); 153.7
2
þ
C(3), C(6)). EI-MS: 654 (30, M , Br pattern), 57 (100). Anal. calc. for C H Br O (654.6): C 62.38, H
.31; found: C 62.25, H 8.24.
2
34 54
2
2

Helvetica Chimica Acta – Vol. 96 (2013)
2027
2
,7-Dibromo-3,6-bis[(2-ethylhexyl)oxy]naphthalene (6d). To a soln of K CO (5.3 g, 38.3 mmol),
2
3
Aliquat 336 (0.5 g), and 5 (5.0 g, 15.7 mmol) in 200 ml of 1,2-dimethoxyethane, 2-(2-ethylhexyl)-4-
methylbenzenesulfonate (9.4 g, 33.0 mmol) was added. After 3-d boiling, the solvent was evaporated,
and the residue was purified by column filtration (SiO (6 ꢁ 30 cm); CH Cl /petroleum ether (PE; b.p.
2
2
2
1
4
4
0 – 708) 1:1). Yield: 6.05 g (71%). Colorless oil. H-NMR (CDCl ): 0.92 – 1.01 (m, 4 Me); 1.20 – 1.40 (m,
3
3
CH ); 1.40 – 1.65 (m, 4 CH ); 1.78 – 1.95 (m, 2 CH); 3.95 (d, J ¼ 5.5, 2 OCH ); 7.00 (s, HꢀC(4),
2
2
2
13
HꢀC(5)); 7.82 (s, HꢀC(1), HꢀC(8)). C-NMR (CDCl ): 11.1, 14.0 (Me); 22.9, 23.9, 28.9, 30.4 (CH ); 39.2
3
2
(
(
(
CH); 71.2 (CH O); 106.1 (C(4), C(5)); 111.7 (C(2), C(7)); 124.8 (C(8a)); 130.6 (C(1), C(8)); 133.8
2
þ
C(4a)); 153.8 (C(3), C(6)). EI-MS: 542 (12, M , Br pattern), 318 (100). Anal. calc. for C H Br O
2
26 38
2
2
542.4): C 57.58, H 7.06; found: C 57.49, H 7.08.
2
,7-Dibromo-3,6-bis[(2-butylhexyl)oxy]naphthalene (6e). Prepared as described for 6b. Yield: 58%.
1
Colorless oil. H-NMR (CDCl ): 0.75 – 0.90 (m, 4 Me); 1.15 – 1.35 (m, 8 CH ); 1.35 – 1.50 (m, 4 CH );
3
2
2
3
1
.75 – 1.93 (m, 2 CH); 3.97 (d, J ¼ 5.2, 2 CH O); 6.98 (s, HꢀC(4), HꢀC(5)); 7.81 (s, HꢀC(1), HꢀC(8)).
2
1
3
C-NMR (CDCl ): 14.1 (Me); 23.1, 29.2, 31.2 (CH ); 37.9 (CH); 72.0 (CH O); 106.4 (C(4), C(5)); 112.0
3
2
2
þ
(
C(2), C(7)); 125.1 (C(8a)); 130.8 (C(1), C(8)); 134.1 (C(4a)); 154.0 (C(3), C(6)). EI-MS: 598 (10, M ),
3
18 (100). Anal. calc. for C H Br O (598.5): C 60.20, H 7.75; found: C 60.01, H 7.92.
30 46 2 2
3,6-Dimethoxynaphthalene-2,7-dicarbaldehyde (7a). A 1.6m soln. of BuLi in hexane (37 ml,
5
9.0 mmol) was slowly dropped to 6a (8.5 g, 24.6 mmol) dissolved in 200 ml of Et O. The temp. of the
2
used cold bath (solid CO /PE (b.p. 40 – 708)) was regulated, so that the magnetic stirring of the mixture
2
worked sufficiently. The yellow-red soln. was then kept for 15 min at ꢀ 788. DMF (4.5 ml, 59 mmol) was
added slowly at 08. After 1 h stirring at r.t., the reaction was quenched first by the addition of 1 ml of H O
2
and then 50 ml of 2m HCl. The formed precipitate was filtered, washed with H O, and treated with
2
1
boiling acetone to give. 7a (4.15 g, 69%). Light-yellow solid. M.p. 2458 ([31]: m.p. 232 – 2358). H-NMR
(
CDCl ): 4.02 (s, 2 MeO); 7.06 (s, HꢀC(4), HꢀC(5)); 8.35 (s, HꢀC(1), HꢀC(8)); 10.47 (s, 2 CHO). The
3
compound was identical to an authentic sample [31].
3
,6-Bis(hexyloxy)naphthalene-2,7-dicarbaldehyde (7b). Prepared as described for 7a. Yield: 77%.
1
Colorless solid. M.p. 798. H-NMR (CDCl ): 0.83 – 0.93 (m, 2 Me); 1.21 – 1.40 (m, 4 CH ); 1.40 – 1.59 (m,
3
2
3
2
CH ); 1.83 – 1.95 (m, 2 CH ); 4.12 (t, J ¼ 6.4, 2 CH O); 6.97 (s, HꢀC(4), HꢀC(5)); 8.29 (s, HꢀC(1),
2
2
2
13
HꢀC(8)); 10.48 (s, 2 CHO). C-NMR (CDCl ): 14.0 (Me); 22.5, 25.7, 28.9, 31.5 (CH ); 68.6 (CH O);
3
2
2
1
05.6 (C(4), C(5)); 121.7 (C(8a)); 124.6 (C(2), C(7)); 132.6 (C(1), C(8)); 142.3 (C(4a)); 159.7 (C(3),
þ
C(6)); 189.3 (CHO). EI-MS: 384 (24, M ), 216 (100). Anal. calc. for C H O (384.5): C 74.97, H 8.39;
24
32
4
found: C 74.94, H 8.29.
3
,6-Bis(dodecyloxy)naphthalene-2,7-dicarbaldehyde (7c). Prepared as described for 7a. Yield: 75%.
1
Colorless crystals. M.p. 89 – 918. H-NMR (CDCl ): 0.82 – 0.91 (m, 2 Me); 1.20 – 1.40 (m, 16 CH ); 1.40 –
3
2
3
1
.60 (m, 2 CH ); 1.80 – 1.96 (m, 2 CH ); 4.12 (t, J ¼ 6.4, 2 CH O); 6.98 (s, HꢀC(4), HꢀC(5)); 8.30 (s,
2
2
2
13
HꢀC(1), HꢀC(8)); 10.48 (s, 2 CHO). C-NMR (CDCl ): 14.1 (Me); 22.6, 26.1, 28.9, 29.3, 29.6, 31.9
3
(
(
CH , partly superimposed); 68.6 (CH O); 105.5 (C(4), C(5)); 121.7 (C(8a)); 124.7 (C(2), C(7)); 132.6
2 2
þ
C(1), C(8)); 142.3 (C(4a)); 159.7 (C(3), C(6)); 189.3 (CHO). EI-MS: 552 (66, M ), 215 (100). Anal.
calc. for C H O (552.8): C 78.21, H 10.21; found: C 78.32, H 10.09.
36
56
4
3
,6-Bis(2-ethylhexyl)naphthalene-2,7-dicarbaldehyde (7d). Prepared as described for 7a. Yield 68%.
1
Colorless oil. H-NMR (CDCl ): 0.83 – 0.99 (m, 4 Me); 1.20 – 1.42 (m, 4 CH ); 1.42 – 1.60 (m, 4 CH );
3
2
2
3
1
1
.73 – 1.91 (m, 2 CH); 4.00 (d, J ¼ 6.4, 2 CH
2
O); 6.97 (s, HꢀC(4), HꢀC(5)); 8.18 (s, HꢀC(1), HꢀC(8));
13
0.42 (s, 2 CHO). C-NMR (CDCl ): 11.1, 13.9 (Me); 22.9, 24.0, 29.0, 30.6 (CH ); 39.3 (CH); 71.1
3
2
(
(
9
CH
2
O); 105.6 (C(4), C(5)); 121.7 (C(8a)); 124.8 (C(2), C(7)); 132.3 (C(1), C(8)); 142.3 (C(4a)); 159.8
þ
C(3), C(6)); 188.8 (CHO). EI-MS: 440 (12, M ), 216 (100). Anal. calc. for C H O (440.6): C 76.33, H
.15; found: C 76.50, H 9.27.
28
40
4
3
,6-Bis[(2-butylhexyl)oxy]naphthalene-2,7-dicarbaldehyde (7e). Prepared as described for 7a. Yield:
1
5
4
8%. Colorless oil. H-NMR (CDCl ): 0.80 – 0.95 (m, 4 Me); 1.20 – 1.35 (m, 8 CH ); 1.35 – 1.50 (m,
3
2
3
CH ); 1.75 – 1.95 (m, 2 CH); 4.00 (d, J ¼ 5.2, 2 CH O); 7.00 (s, HꢀC(4), HꢀC(5)); 8.25 (s, HꢀC(1),
2
2
13
HꢀC(8)); 10.46 (s, 2 CHO). C-NMR (CDCl ): 13.9 (Me); 22.9, 28.9, 31.0 (CH ); 37.7 (CH); 71.2
3
2
(
(
9
CH O); 105.5 (C(4), C(5)); 121.6 (C(8a)); 124.6 (C(2), C(7)); 132.3 (C(1), C(8)); 142.3 (C(4a)); 159.7
2
þ
C(3), C(6)); 188.9 (CHO). EI-MS: 496 (2, M ), 216 (100). Anal. calc. for C H O (496.7): C 77.38, H
.74; found: C 77.16, H 9.58.
32
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4

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Helvetica Chimica Acta – Vol. 96 (2013)
2
-[(2-Ethylhexyl)oxy]benzaldehyde (9b). To a soln. of K CO (6.9 g, 49.9 mmol), Aliquat 336
2
3
(
(
0.5 g), and salicylaldehyde (8) (5.0 g, 40.9 mmol) in 200 ml of dioxane, 2-ethylhexyl p-toluenesulfonate
11.7 g, 41.0 mmol) was added dropwise. After 3 d at 808, the solvent was evaporated, and the product
was purified by column filtration (SiO (5 ꢁ 40 cm); CH Cl ). Yield: 8.05 g (84%). Colorless oil.
2
2
2
1
H-NMR (CDCl ): 0.80 – 0.91 (m, 2 Me); 1.19 – 1.30 (m, 2 CH ); 1.30 – 1.50 (m, 2 CH ); 1.65 – 1.80 (m,
3
2
2
3
CH); 3.89 (d, J ¼ 5.3, CH O); 6.86 – 6.95 (m, HꢀC(3), HꢀC(5)); 7.40 – 7.60 (m, HꢀC(4)); 7.72 – 7.78 (m,
2
13
HꢀC(6)); 10.46 (s, CHO). C-NMR (CDCl ): 11.0, 13.9 (Me); 22.8, 23.8, 28.9, 30.4 (CH ); 39.2 (CH);
3
2
7
(
0.6 (CH O); 112.3 (C(3)); 120.2 (C(5)); 124.8 (C(1)); 127.9 (C(4)); 135.8 (C(6)); 161.6 (C(2)); 189.4
2
þ
CHO). EI-MS: 234 (22, M ), 122 (100). Anal. calc. for C H O ( 234.3): C 76.88, H 9.46; found: C
15
22
2
7
6.95, H 9.24.
-[(2-Butylhexyl)oxy]benzaldehyde (9c). Prepareded as described for 9b, using 1-bromo-2-
butylhexane. The chromatographic purification was performed with PE (40 – 708)/CH Cl 2 :1. Yield:
2
2
2
1
9
2
4%. Colorless oil. H-NMR (CDCl ): 0.82 – 0.89 (m, 2 Me); 1.24 – 1.31 (m, 4 CH ); 1.30 – 1.50 (m,
3 2
2
CH ); 1.70 – 1.85 (m, CH); 3.90 (d, J ¼ 5.3, CH O); 6.87 – 6.97 (m, HꢀC(3), HꢀC(5)); 7.40 – 7.50 (m,
2
2
13
HꢀC(4)); 7.75 – 7.84 (m, HꢀC(6)); 10.49 (s, CHO). C-NMR (CDCl ): 14.9 (Me); 22.9, 29.0, 31.1 (CH );
3
2
3
7.9 (CH); 71.2 (CH O); 12.4 (C(3)); 120.3 (C(5)); 125.1 (C(1)); 128.0 (C(4)); 135.7 (C(6)); 161.7 (C(2));
2
1
89.4 (CHO). EI-MS: 262 (8), 43 (100). Anal. calc. for C H O (262.4): C 77.82, H 9.99; found: C 77.65,
17
26
2
H 9.71.
{
2-[(2-Ethylhexyl)oxy]phenyl}methanol (10b). Aldehyde 9b (7.0 g, 29.9 mmol) was slowly dropped
to a soln. of LiAlH (0.57 g, 15.0 mmol) in 200 ml of dry Et O, so that the Et O boiled gently. After 1 h
4
2
2
heating to reflux, the reaction was quenched with H O. The formed precipitate was dissolved by the
2
addition of 10% H SO , and the org. phase was separated, neutralized with a sat. aq. soln. of NaHCO ,
2
4
3
and washed with H O. The soln. was dried (MgSO ) and evaporated. Purification by column filtration
2
4
1
(
2
SiO2 (6 ꢁ 40 cm); CH Cl ) gave 10b (6.0 g, 85%). Colorless oil. H-NMR (CDCl ): 0.80 – 0.91 (m,
2
2
3
3
Me); 1.20 – 1.31 (m, 3 CH ); 1.31 – 1.50 (m, CH ); 1.63 – 1.77 (m, CH); 3.91 (d, J ¼ 5.4, CH O); 4.70 (s,
2
2
2
13
CH OH); 6.86 – 6.93 (m, HꢀC(3), HꢀC(5)); 7.22 – 7.30 (m, HꢀC(4), HꢀC(6)). C-NMR (CDCl ): 11.9,
2
3
1
(
3.9 (Me); 22.8, 24.0, 29.0, 30.6 (CH ); 39.1 (CH); 61.9 (CH OH); 70.0 (CH O); 110.7 (C(3)); 120.3
2 2 2
þ
C(5)); 128.2, 128.6 (C(4), C(6)); 129.2 (C(1)); 156.8 (C(2)). EI-MS: 236 (17, M ), 106 (100). Anal. calc.
for C H O (236.4): C 76.23, H 10.23; found: C 76.05, H 10.42.
15
24
2
{
2-[(2-Butylhexyl)oxy]phenyl}methanol (10c). Prepared as described for 10b. Yield: 98%. Colorless
1
3
oil. H-NMR (CDCl ): 0.88 – 0.96 (m, 2 Me); 1.22 – 1.50 (m, 6 CH ); 1.73 – 1.86 (m, CH); 3.88 (d, J ¼ 5.4,
3
2
13
CH O); 4.68 (s, CH OH); 6.81 – 7.00 (m, HꢀC(3), HꢀC(5)); 7.19 – 7.31 (m, HꢀC(4), HꢀC(6)). C-NMR
2
2
(
(
CDCl ): 13.9 (Me); 22.9, 25.4, 31.1 (CH ); 38.9 (CH); 61.6 (CH OH); 70.3 (CH O); 110.6 (C(3)); 120.2
3 2 2 2
þ
C(5)); 128.5, 128.7 (C(4), C(6)); 129.1 (C(1)); 156.7 (C(2)). EI-MS: 264 (4, M ), 73 (100). Anal. calc. for
C H O (264.4): C 77.22, H 10.67; found: C 77.05, H 10.57.
17
28
2
(
2-Methoxybenzyl)(triphenyl)phosphonium Bromide (11a). Alcohol 10a (26.4 g, 0.19 mol) and
Ph P · HBr (65.6 g, 0.19 mol) were heated to reflux in 200 ml of dry CHCl for 12 h. The formed H O was
3
3
2
continuously separated. The solvent was evaporated, and the residue was recrystallized from Et O, to
2
which EtOH was added until the whole bromide was dissolved. Yield: 88.0 g (ca. 100%). Colorless
1
2
powder. M.p. 238 – 2408. H-NMR ((D )DMSO): 3.17 (s, MeO); 4.95 (d, J(H,P) ¼ 14.8, CH ); 6.75 – 6.85
6
2
13
(
(
(
m, HꢀC(3), HꢀC(5)); 7.04 – 7.11 (m, HꢀC(6)); 7.23 – 7.33 (m, HꢀC(4)); 7.59 – 7.90 (m, Ph P). C-NMR
3
1
CD OD): 26.2 (PCH , J(C,P) ¼ 49.1); 58.4 (MeO); 112.2 (C(3)); 117.0 (C , Ph); 118.6, 120.5, 122.0
3
2
q
C(4), C(5), C(6)); 131.3, 135.3, 136.4 (CH, Ph P); 132.4 (C(1)); 158.9 (C(2)). FD-MS: 383 (100, [M ꢀ
3
þ
Br] ), 384 (27). Anal. calc. for C H BrOP (463.4): C 67.40, H 5.22; found: C 67.01, H 4.90.
26
24
{
2-[(2-Ethylhexyl)oxy]benzyl}(triphenyl)phosphonium Bromide (11b). Prepared as described for
1
1
1a. Yield: quant. Colorless powder. M.p. 1928. H-NMR (CDCl ): 0.70 – 0.78 (m, Me); 0.80 – 0.88 (m,
3
3
2
Me); 1.05 – 1.25 (m, 4 CH ); 2.01 – 2.11 (m, CH); 3.23 (d, J ¼ 4.3, CH O); 5.17 (d, J(P,H) ¼ 13.8, 2 H,
2
2
PCH ); 6.56 – 6.63 (m, HꢀC(2)); 6.70 – 6.80 (m, HꢀC(5)); 7.14 – 7.24 (m, HꢀC(4), HꢀC(6)); 7.50 – 7.80
2
13
1
(
4
1
m, Ph P). C-NMR (CD OD): 11.0, 14.0 (Me); 22.9, 23.5, 29.0, 30.3 (CH ); 24.9 (PCH , J(C,P) ¼
3
3
2
2
8.2); 39.1 (CH); 70.3 (CH O); 111.2 (C(3)); 115.3 (C , Ph); 117.1, 118.8, 121.0 (C(4), C(5), C(6));
2 q
þ
30.0, 134.0, 134.9 (CH, Ph); 132.1 (C(1)); 156.9 (C(2)). FD-MS: 481 (100 [M ꢀ Br] ). Anal. calc. for
C H BrOP (561.6): C 70.58, H 6.82; found: C 70.70, H 6.94.
33
38

Helvetica Chimica Acta – Vol. 96 (2013)
2029
{
2-[(2-Butylhexyl)oxy]benzyl}(triphenyl)phosphonium Bromide (11c). Prepared as described for
1
1
(
1a. Yield: quant. Colorless powder. M.p. 1888. H-NMR ((D )DMSO): 0.80 – 0.89 (m, 2 Me); 1.10 – 1.30
6
2
m, 13 H, CH , CH); 3.38 (m, CH O); 4.87 (d, J(P,H) ¼ 15.0, PCH ); 6.80 – 7.01 (m, HꢀC(3), HꢀC(4),
2
2
2
13
HꢀC(5)); 7.25 – 7.35 (m, HꢀC(6)); 7.50 – 7.95 (m, Ph P). C-NMR (CD OD): 14.4 (Me); 24.0, 30.2, 32.0
3
3
1
(
CH ); 25.6 (PCH , J(C,P) ¼ 49.7); 72.4 (CH O); 113.2 (C(3)); 116.5 (C , Ph); 118.9, 119.7, 121.9 (C(4),
2
2
2
q
þ
C(5), C(6)); 131.4, 135.1, 136.4 (CH, Ph); 131.8 (C(1)); 158.6 (C(2)). FD-MS: 509 (100 [M ꢀ Br] ). Anal.
calc. for C H BrOP (589.6): C 71.30, H 7.18; found: C 71.05, H 7.05.
35
42
Dodecyl 2-Methylphenyl Ether (13a). Prepared as described for 9b, with 12a (25.0 g, 0.23 mol) and 1-
1
bromododecane (60.0 g, 0.24 mol). Yield: 62.9 g (99%). Colorless oil. H-NMR (CDCl ): 0.90 – 1.00 (m,
3
3
Me); 1.30 – 1.55 (m, 9 CH ); 1.78 – 1.95 (m, CH ); 2.28 (s, Me); 3.99 (t, J ¼ 6.4, CH O); 6.81 – 6.92 (m,
2
2
2
13
HꢀC(3), HꢀC(5)); 7.14 – 7.22 (m, HꢀC(4), HꢀC(6)). C-NMR (CDCl ): 14.1, 16.2 (Me); 22.7, 26.2, 28.2,
3
2
(
8.8, 29.4, 29.6, 31.9 (CH , partly superimposed); 67.8 (OCH ); 110.8 (C(3)); 120.0 (C(5)); 126.6, 130.5
2 2
þ
C(4), C(6)); 126.8 (C(1)); 157.2 (C(2)). EI-MS: 276 (2, M ), 135 (39), 57 (82), 43 (100). Anal. calc. for
C H O (276.5): C 82.55, H 11.67; found: C 82.65, H 11.27.
19
32
1,2-Bis(hexyloxy)-3-methylbenzene (13b). Prepared as described in [32]. Yield: 97%. Pale-yellow
oil.
1
,2-Bis(dodecyloxy)-3-methylbenzene (13c). Prepared as described for 9b. Yield: 91%. Pale-yellow
1
oil. H-NMR (CDCl ): 0.85 – 0.95 (m, 2 Me); 1.20 – 1.41 (m, 16 CH ); 1.41 – 1.60 (m, 2 CH ); 1.71 – 1.88
3
2
2
(
m, 2 CH ); 2.25 (s, Me); 3.90 – 4.00 (m, 2 CH O); 6.71 – 6.79 (m, HꢀC(4), HꢀC(6)); 6.85 – 6.93 (m,
2
2
13
HꢀC(5)). C-NMR (CDCl ): 14.1, 14.1, 16.0 (Me); 22.7, 26.2, 29.4, 29.5, 29.7, 30.5, 31.9 (CH , partly
3
2
superimposed); 68.4, 72.6 (CH O), 111.8 (C(4)); 122.6, 123.2 (C(5), C(6)); 132.1 (C(1)); 146.8, 152.3
2
þ
(
C(2), C(3)). EI-MS: 460 (15, M ), 124 (97), 56 (98), 54 (53), 43 (100). Anal. calc. for C H O (460.8):
31
56
2
C 80.81, H 12.25; found: C 81.02, H 12.16.
Diethyl [2-(Dodecyloxy)benzyl]phosphonate (14a). N-Bromosuccinimide (NBS; 25.5 g, 0.14 mol),
1
3a (39.6 g, 0.14 mol), and azobisisobutyronitrile (AIBN; 0.2 g) were heated in 200 ml of dry CCl to
4
reflux for 4 h. The formed succinimide was filtered off and washed with CCl . The solvent was
4
evaporated, and the residue was reacted with (EtO) P (21.9 g, 0.13 mol) at 1608. The formed
3
bromoethane was continuously distilled off. After ca. 6 h, the reaction was complete. The purification of
the product was performed by column filtration (SiO (6 ꢁ 40 cm); Et O). Yield: 32.5 g (55%). Almost
2
2
1
3
colorless oil. H-NMR (CDCl ): 0.80 – 0.89 (m, Me); 1.15 (t, J ¼ 5.7, 2 Me); 1.20 – 1.47 (m, 9 CH ); 1.70 –
3
2
2
1
.84 (m, CH ); 3.22 (d, J(P,H) ¼ 21.6, PCH ); 3.88 – 4.06 (m, 3 CH O); 6.76 – 6.89 (m, HꢀC(3),
2
2
2
13
HꢀC(5)); 7.06 – 7.20 (m, HꢀC(4)); 7.25 – 7.33 (m, HꢀC(6)). C-NMR (CDCl ): 13.8, 16.0 (Me); 22.4,
3
1
2
1
5.8, 26.1 ( J(PC) ¼ 139.2); 29.0, 29.3, 31.6 (CH , partly superimposed); 61.5 (MeCH O); 67.9 (CH O);
2
2
2
þ
11.0 (C(3)); 120.0, 120.0, 127.7 (C(4), C(5), C(6)); 130.8 (C(1)); 156.4 (C(2)). EI-MS: 412 (26, M ), 244
(
100). Anal. calc. for C H O P (412.6): C 66.96, H 10.02; found: C 66.80, H 10.15.
23 41 4
Diethyl [2,3-Bis(hexyloxy)benzyl]phosphonate (14b). Prepared as described for 14a. Yield: 48%.
1
Light-yellow oil. H-NMR (CDCl ): 0.80 – 0.90 (m, 2 Me); 1.10 – 1.50 (m, 6 CH , 2 OCH ꢀMe); 1.65 –
3
2
2
2
1
6
3
1
.80 (m, 2 CH ); 3.20 (d, J(P,H) ¼ 21.8, PCH ); 3.56 – 4.10 (m, 4 CH O); 6.68 – 6.75 (m, HꢀC(4));
2
2
2
13
.83 – 6.95 (m, HꢀC(5), HꢀC(6)). C-NMR (CDCl ): 14.0, 14.0, 16.3 (Me); 22.6, 22.6, 25.7, 25.8, 29.3,
3
1
0.3, 31.5, 31.7 (CH ); 26.6 ( J(P,C) ¼ 139.7, PCH ); 62.0 (MeCH O); 68.5, 73.1 (CH O); 112.1 (C(4));
2
2
2
2
þ
22.5, 123.3 (C(5), C(6)); 125.5 (C(1)); 146.7, 152.4 (C(2), C(3)). EI-MS: 427 (25, [M ꢀ H] ), 108 (100).
Anal. calc. for C H O P (428.6): C 64.46, H 9.64; found: C 64.70, H 9.75.
2
3
41
5
Diethyl [2,3-Bis(dodecyloxy)benzyl]phosphonate (14c). Prepared as described for 14a. The CC was
1
performed with CH Cl /AcOEt 4 :1. Yield: 25%. Colorless solid. M.p. 37 – 388. H-NMR (CDCl ): 0.82 –
2
2
3
2
0
.90 (m, 2 Me); 1.19 – 1.50 (m, 18 CH , 2 MeCH O); 1.68 – 1.86 (m, 2 CH ); 3.22 (d, J(P,H) ¼ 21.8,
2
2
2
13
PCH ); 3.89 – 4.10 (m, 4 CH O); 6.70 – 6.79 (m, HꢀC(4)); 6.88 – 7.00 (m, HꢀC(5), HꢀC(6)). C-NMR
2
2
(
CDCl ): 14.0, 16.3 (Me); 22.6, 26.0, 26.1, 29.3, 29.6, 30.3, 31.8 (CH , partly superimposed); 26.5 (d,
3
2
1
J(P,C) ¼ 139.6, PCH
2
); 61.8 (MeCH
2
O); 68.4, 73.1 (CH
2
O); 112.0 (C(4)); 122.4, 123.2 (C(5), C(6));
25.5 (C(1)); 146.7, 152.2 (C(2), C(3)). EI-MS: 596 (23, M ), 428 (100). Anal. calc. for C H O P
þ
1
35
65
5
(
596.9): C 70.43, H 10.98; found: C 70.54, H 10.99.
,7-Dimethoxy-3,6-bis[(E)-2-(2-methoxyphenyl)ethenyl]naphthalene (1a). BuLi in heptane (13.7 ml
2
of a 2.7m soln.; 37.0 mmol) was slowly dropped at 08 to a soln. of 11a (17.7 g, 38.2 mmol) in 110 ml of THF.
The mixture turned red. After 15 min at r.t., 7a (4.1 g, 16.8 mmol), suspended in 70 ml of THF, was

2
030
Helvetica Chimica Acta – Vol. 96 (2013)
added. The red color disappeared, and a blue fluorescence could be observed. The mixture was heated to
reflux for 5 h, before 50 ml of H O and 100 ml of 2m HCl were added. Et O was added in order to reach a
2
2
good phase separation. The aq. phase was extracted two times with 100 ml of Et O each. The unified org.
2
phases were dried (MgSO ) and evaporated. The residue was purified by column filtration (SiO (6 ꢁ
4
2
4
0 cm); PE (b.p. 40 – 708)/CHCl 1:4). Yield: 5.6 g (74%). Yellow product. Recrystallization from
3
1
EtOH gave the pure (E,E)-isomer. M.p. 184 – 1868. H-NMR (CDCl ): 3.90 (s, 2 MeO); 3.96 (s, 2 MeO);
3
6
.85 – 7.00 (m, 2 HꢀC(3’), 2 HꢀC(5’)); 7.01 (s, HꢀC(1), HꢀC(8)); 7.19 – 7.29 (m, 2 HꢀC(4’)); 7.52, 7.62
3
13
(AB, J ¼ 16.7, 4 olefin. H); 7.65 – 7.74 (m, 2 HꢀC(6’)); 8.03 (s, HꢀC(4), HꢀC(5)). C-NMR (CDCl ):
3
5
5.4, 55.5 (MeO); 104.5 (C(1), C(8)); 110.9 (C(3’)); 120.7 (C(5’)); 123.8, 123.9, 125.4, 126.4, 128.4 (C(4),
C(5), C(4’), C(6’), olefin. C); 124.1, 126.6, 127.1, 134.7 (C(2), C(7), C(4a), C(8a), C(1’)); 156.1, 156.8
þ
(
C(2), C(7), C(2’)). FD-MS: 452 (100, M ). Anal. calc. for C H O (452.6): C 79.62, H 6.24; found: C
30
28
4
7
9.57, H 6.07.
2
,7-Bis(dodecyloxy)-3,6-bis{(E)-2-[2-(dodecyloxy)phenyl]ethenyl}naphthalene (1b). Prepared as
1
described for 1a. Yield: 78%. Yellow solid. M.p. 648. H-NMR (CDCl ): 0.80 – 1.12 (m, 4 Me); 1.15 –
3
1
.47 (m, 32 CH ); 1.47 – 1.59 (m, 4 CH ); 1.80 – 2.00 (m, 4 CH ); 3.98 – 4.15 (m, 4 CH O); 6.88 – 6.99
2
2
2
2
3
(
1
m, 2 HꢀC(3’), 2 HꢀC(5’)); 6.99 (s, HꢀC(1), HꢀC(8)); 7.17 – 7.27 (m, 2 HꢀC(4’)); 7.55, 7.65 (AB, J ¼
13
6.6, 4 olefin. H); 7.62 – 7.68 (m, 2 HꢀC(6’)); 7.96 (s, HꢀC(4), HꢀC(5)). C-NMR (CDCl ): 14.1
3
(
2 2
Me); 22.7, 26.2, 29.3, 29.4, 29.5, 29.7, 31.9 (CH , partly superimposed); 68.3, 68.5 (CH O); 105.0 (C(1),
C(8)); 112.1 (C(3’)); 120.6 (C(5’)); 124.1, 124.4, 125.7, 126.6, 128.2 (C(4), C(5), C(4’), C(6’), olefin. C);
1
24.0, 126.7, 127.5, 134.7 (C(3), C(6), C(1’), C(4a), C(8a)); 155.7, 156.5 (C(2), C(7), C(2’)). FD-MS: 1069
þ
(
100, M ). Anal. calc. for C H O (1069.7): C 83.09, H 10.93; found: C 83.38, H 10.82.
74
116
4
2
,7-Bis[(2-ethylhexyl)oxy]-3,6-bis(2-{2-[(2-ethylhexyl)oxy]phenyl}ethenyl)naphthalene (1c). Pre-
1
pared as described for 1a. Yield: 74%. Yellow oil. Mixture of stereoisomers. H-NMR (CDCl ): 0.90 –
3
1
1
3
1
1
.10 (m, 8 Me); 1.33 – 1.67 (m, 16 CH ); 1.70 – 2.00 (m, 4 CH); 3.88 – 4.10 (m, 4 CH O); 6.60 – 8.03 (m,
2
2
13
6 arom. and olefin. H). C-NMR (CDCl ): 11.2, 14.1 (Me); 23.1, 24.0, 24.1, 24.2, 24.3, 29.1, 29.2, 30.6,
3
0.7, 30.8, 30.9 (CH ); 39.3, 39.4, 39.5 (CH); 70.5, 70.6, 70.9, 71.2 (CH O); 104.5, 104.7, 111.6, 112.0, 119.8,
2
2
19.9, 120.5, 123.3, 123.6, 125.1, 125.4, 126.0, 128.0, 128.1, 128.7, 128.8, 129.5, 129.7 (arom. and olefin. CH);
23.0, 123.5, 125.5, 126.5, 126.6, 126.6, 126.7, 127.5, 134.5, 134.7 (arom. C ); 155.7, 156.2, 156.5, 156.8, 157.0
q
þ
(
arom. C O). FD-MS: 845 (100, M ). Anal. calc. for C H O (845.3): C 82.41, H 10.02; found: C 82.24,
q
58 84
4
H 10.13.
2
,7-Bis[(2-butylhexyl)oxy]-3,6-bis(2-{2-[(2-butylhexyl)oxy]phenyl}ethenyl)naphthalene (1d). Pre-
1
pared as described for 1a. Mixture of stereoisomers. Yield: 89%. Yellow oil. H-NMR (CDCl ): 0.90 –
3
1
.08 (m, 8 Me); 1.30 – 1.65 (m, 24 CH ); 1.73 – 2.01 (m, 4 CH); 3.85 – 4.10 (m, 4 CH O); 6.60 – 8.03 (m,
2
2
13
1
6 arom. and olefin. H). C-NMR (CDCl ): 14.1 (Me); 21.4, 22.6, 23.1, 26.9, 29.1, 31.2, 31.3, 31.4, 31.6
3
(
CH ); 37.8, 37.9 (CH); 104.5, 104.6, 111.6, 111.8, 119.7, 120.4, 123.0, 123.5, 125.1, 125.2, 125.4, 125.9, 126.5,
2
1
1
8
27.6, 128.0, 128.2, 128.7, 129.0, 129.5, 129.6, 134.5, 134.6 (arom. CH and C ); 155.8, 156.1, 156.3, 156.8,
q
þ
57.0 (arom. C O). FD-MS: 957 (100, M ). Anal. calc. for C H O (957.5): C 82.79, H 10.53; found: C
q
66 100
4
2.60, H 10.42.
2
,7-Bis{(E)-2-[2,3-bis(hexyloxy)phenyl]ethenyl}-3,6-bis(hexyloxy)naphthalene (1e). Prepared as
1
described for 1a. Yield: 40%. Yellow solid. M.p. 35 – 378. H-NMR (CDCl ): 0.85 – 1.00 (m, 6 Me);
3
1
.30 – 1.45 (m, 12 CH ); 1.45 – 1.63 (m, 6 CH ); 1.80 – 2.00 (m, 6 CH ); 3.98 – 4.15 (m, 6 CH O); 6.80 – 6.87
2
2
2
2
(
(
2
m, 2 HꢀC(4’)); 7.00 (s, HꢀC(1), HꢀC(8)); 7.00 – 7.09 (m, 2 HꢀC(5’)); 7.27 – 7.33 (m, 2 HꢀC(6’)); 7.57, 7.65
3
13
AB, J ¼ 16.7, 4 olefin. H); 7.99 (s, HꢀC(4), HꢀC(5)). C-NMR (CDCl ): 14.2 (Me); 22.6, 22.6, 22.7,
3
5.9, 25.9, 26.0, 29.2, 29.4, 30.4, 31.6, 31.6, 31.8 (CH ); 68.3, 68.7, 73.7 (CH O); 105.1 (C(1), C(8)); 112.2
2 2
(
C(4’)); 117.9 (C(5’)); 123.6, 123.8, 124.7 (C(4), C(5), olefin. C); 123.8, 126.5, 132.7, 134.9 (C(3), C(6),
þ
C(4a), C(8a), C(1’)); 146.4, 152.7, 155.7 (C(2), C(7), C(2’), C(3’)). FD-MS: 933 (100, M ). Anal. calc. for
C H O (933.4): C 79.78, H 9.93; found: C 79.73, H 10.03.
62
92
6
2
,7-Bis{(E)-2-[2,3-bis(dodecyloxy)phenyl]ethenyl}-3,6-bis(dodecyloxy)naphthalene (1f). Prepared
1
as described for 1a. Yield: 92%. Yellow solid. M.p. 32 – 358. H-NMR (CDCl ): 0.82 – 0.95 (m, 6 Me);
3
1
.16 – 1.45 (m, 48 CH ); 1.45 – 1.62 (m, 6 CH ); 1.78 – 1.98 (m, 6 CH ); 3.96 – 4.18 (m, 6 CH O); 6.78 – 6.85
2
2
2
2
(
m, 2 HꢀC(4’)); 6.99 (s, HꢀC(1), HꢀC(8)); 6.99 – 7.07 (m, 2 HꢀC(5’)); 7.25 – 7.32 (m, 2 HꢀC(6’)); 7.55,
3
13
7.64 (AB, J ¼ 16.6, 4 olefin. H); 7.97 (s, HꢀC(4), HꢀC(5)). C-NMR (CDCl ): 14.1 (Me); 22.7, 26.3, 26.4,
3
2
9.4, 29.5, 29.7, 29.8, 31.9 (CH , partly superimposed); 68.4, 68.8, 73.7 (CH O); 105.2 (C(1), C(8)); 112.4
2
2

Helvetica Chimica Acta – Vol. 96 (2013)
2031
(
C(4’)); 118.0 (C(5’)); 123.6, 123.8, 124.8, 125.8 (C(4), C(5), C(6’), olefin. C); 124.1 (C(4a)); 132.7 (C(3),
þ
C(6), 134.9 (C(8a)); 146.6, 152.7, 155.8 (C(2), C(7), C(2’), C(3’)). FD-MS: 1438 (100, M ). Anal. calc. for
C H O (1438.4): C 81.83, H 11.49; found: C 81.65, H 11.71.
98
164
6
2
,7-Bis{(E)-2-[2,3-bis(hexyloxy)phenyl]ethenyl}-3,6-bis[(2-butylhexyl)oxy]naphthalene (1g). Pre-
1
pared as described for 1a. Yield: 77%. Yellow oil. H-NMR (CDCl ): 0.81 – 0.96 (m, 8 Me); 1.20 – 1.44
3
(
m, 16 CH ); 1.44 – 1.61 (m, 8 CH ); 1.75 – 2.00 (m, 4 CH , 2 CH); 3.95 – 4.10 (m, 6 CH O); 6.78 – 6.85 (m,
2 2 2 2
2
HꢀC(4’)); 6.99 – 7.09 (m, HꢀC(1), HꢀC(8), 2 HꢀC(5’)); 7.20 – 7.31 (m, 2 HꢀC(6’)); 7.60 (ꢂsꢃ, 4 olefin.
13
H); 8.01 (s, HꢀC(4), HꢀC(5)). C-NMR (CDCl ): 14.1 (Me); 22.6, 22.7, 23.1, 25.9, 26.0, 29.1, 29.4, 29.7,
3
3
1
1
0.4, 31.4, 31.6, 31.8 (CH , partly superimposed); 37.9 (CH); 68.6, 71.1, 73.7 (CH O); 104.9 (C(1), C(8));
2
2
12.2 (C(4’)); 117.7 (C(5’)); 123.3, 123.6, 124.3, 125.1 (C(4), C(5), C(6’), olefin. C); 123.8, 126.5, 132.6,
35.0 (C(3), C(6), C(1’), C(4a), C(8a)); 146.3, 152.6, 155.8 (C(2), C(7), C(2’), C(3’)). FD-MS: 1045 (100,
þ
M ). Anal. calc. for C H O (1045.6): C 80.41, H 10.41; found: C 80.60, H 10.51.
70
108
6
General Procedure for the Preparation of the Hexahelicenes 3a – 3g. Depending on the solubility,
0
.1 – 1.0 g of 1a – 1g and the twofold molar amount of I were dissolved in 2,000 ml of dry benzene. The
2
soln. was purged with O -free N for 30 min, and a 5 – 10-fold molar excess of methyloxirane was added
2
2
before the irradiation was started with a Hanovia-450-W medium-pressure lamp, equipped with a Pyrex
filter. When the red color fades after some hours, the irradiation was stopped, and the concentrated soln.
was treated with aq. NaHSO , to remove some still present I , and washed with H O. The purification of
3
2
2
the formed hexahelicene was performed by CC (SiO ) or, in the case of the hardly soluble 3a, by
2
treatment with boiling acetone.
4
,7,10,13-Tetramethoxyhexahelicene (3a). Compound 1a (1.00 g, 2.2 mmol) and 1.12 g (4.4 mmol) I
2
þ
yielded 605 mg (61%) of 3a. M.p. 2188. FD-MS: 448 (100, M ). Anal. calc. for C H O (448.5): C 80.34,
30
24
4
H 5.39; found: C 80.55, H 5.56.
,7,10,13-Tetrakis(dodecyloxy)hexahelicene (3b). Compound 1b (710 mg, 0.66 mmol) and I
4
2
(
355 mg, 1.40 mmol) gave after 5 h irradiation a yellow product, which was purified by CC (SiO (3 ꢁ
2
5
9
1
0 cm); PE (b.p. 40 – 708)/toluene 2 :1) and recrystallization from EtOH. Yield: 580 mg (82%). M.p.
þ
48. FD-MS: 1065 (100, M ). Anal. calc. for C H O (1065.7): C 83.40, H 10.59; found: C 83.04, H
74
112
4
0.65.
,7,10,13-Tetrakis[(2-ethylhexyl)oxy]hexahelicene (3c). Compound 1c (680 mg, 0.80 mmol) and I2
4
(
5
(
408 mg, 1.61 mmol) gave after 22 h irradiation a yellow product, which was purified by CC (SiO (3 ꢁ
2
0 cm); CH Cl ) and recrystallization from MeOH. Yield: 305 mg (45%). M.p. 143 – 1448. FD-MS: 841
2 2
þ
100, M ). Anal. calc. for C H O (841.3): C 82.81, H 9.58; found: C 82.93, H 9.64.
58 80 4
4,7,10,13-Tetrakis[(2-butylhexyl)oxy]hexahelicene (3d). Compound 1d (850 mg, 0.89 mmol) and I2
(
5
1
430 mg, 1.7 mmol) gave after 12 h irradiation a yellow product, which was purified by CC (SiO (3 ꢁ
2
0 cm); PE (b.p. 40 – 708)/CH Cl 3 :1) and recrystallization from MeOH. Yield: 310 mg (37%). M.p.
2 2
þ
068. FD-MS: 953 (100, M ). Anal. calc. for C H O (953.5 ): C 83.14, H 10.15; found: C 83.29, H 10.19.
66
96
4
3
,4,7,10,13,14-Hexakis(hexyloxy)hexahelicene (3e). Compound 1e (1.01 g, 1.08 mmol) and I2
(
5
548 mg, 2.16 mmol) gave after 6 h irradiation a yellow product, which was purified by CC (SiO (3 ꢁ
2
þ
0 cm); PE (b.p. 40 – 708)/toluene 1:3). Yield: 600 mg (60%). M.p. 698. FD-MS: 929 (100, M ). Anal.
calc. for C H O (929.4): C 80.13, H 9.54; found: C 80.24, H 9.47.
62
88
6
3,4,7,10,13,14-Hexakis(dodecyloxy)hexahelicene (3f). Compound 1f (720 mg, 0.50 mmol) and I2
(
5
254 mg, 1.0 mmol) gave after 12 h irradiation a yellow product, which was purified by CC (SiO (3 ꢁ
2
þ
0 cm); PE (b.p. 40 – 708)/toluene 5 :2). Yield: 396 mg (55%). M.p. ꢀ 88. FD-MS: 1434 (100, M ).
Anal. calc. for C H O (1434.4): C 82.06, H 11.24; found: C 81.91, H 11.41.
98
160
6
7,10-Bis[(2-butylhexyl)oxy]-3,4,13,14-tetrakis(hexyloxy)hexahelicene (3g). Compound 1g (1.05 g,
1
.00 mmol) and I (508 mg, 2.00 mmol) gave after 20 h irradiation a yellow product, which was purified
2
by CC (SiO (3 ꢁ 50 cm); CH Cl ). Yield: 200 mg (19%). Light yellow oil, which forms a glassy state at
2
2
2
þ
ꢀ
508. FD-MS: 1041 (100, M ). Anal. calc. for C H O (1041.6): C 80.72, H 10.06; found: C 80.54, H
70 104 6
.89.
9

2
032
Helvetica Chimica Acta – Vol. 96 (2013)
REFERENCES
[
1] M. Gingras, Chem. Soc. Rev. 2013, 42, 968.
[
[
[
[
2] M. Gingras, G. F e´ lix, R. Peresutti, Chem. Soc. Rev. 2013, 42, 1007.
3] M. Gingras, Chem. Soc. Rev. 2013, 42, 1051.
4] Y. Shen, C.-F. Chen, Chem. Rev. 2012, 112, 1463.
5] I. G. Star a´ , I. Star y´ , in ꢂScience of Synthesisꢃ, Eds. J. S. Siegel, Y. Tobe, Thieme Verlag, Stuttgart, 2010,
Vol. 45b, p. 885.
[
6] I. Star y´ , I. G. Star a´ , in ꢂStrained Hydrocarbonsꢃ, Ed. H. Dodziuk, Wiley-VCH, Weinheim, 2009,
p. 166.
[
[
7] A. Urbano, Angew. Chem. 2003, 115, 4116; A. Urbano, Angew. Chem., Int. Ed. 2003, 42, 3986.
8] H. Hopf, ꢂClassics in Hydrocarbon Chemistry: Syntheses, Concepts, Perspectivesꢃ, Wiley-VCH,
Weinheim, 2000, 323.
[
9] K. P. Meurer, F. Vçgtle, ꢂ Helical molecules in organic chemistryꢃ, in ꢂOrganic Chemistryꢃ, Vol. 127,
ꢂTopics in Current Chemistryꢃ, Springer Verlag Berlin, 1983, p. 1.
[
[
[
[
10] F. Aloui, M. Jabli, B. B. Hassine, Synth. Commun. 2013, 43, 277.
11] F. Aloui, M. Jabli, B. B. Hassine, Synth. Commun. 2012, 42, 3620.
12] J. Chen, B. Captain, N. Takenaka, Org. Lett. 2011, 13, 1654.
ˇ
13] Z. Krausov a´ , P. Sehnal, B. P. Bondzic, S. Chercheja, P. Eilbracht, I. G. Star a´ , D. Saman, I. Star y´ , Eur.
J. Org. Chem. 2011, 3849.
[
[
14] M. R. Crittall, H. S. Rzepa, D. R. Carbery, Org. Lett. 2011, 13, 1250.
15] N. Takenaka, J. Chen, B. Captain, R. S. Sarangthem, A. Chandrakumar, J. Am. Chem. Soc. 2010, 132,
4536.
[
[
16] J. Chen, N. Takenaka, Chem.ꢀEur. J. 2009, 15, 7268.
17] N. Takenaka, R. S. Sarangthem, B. Captain, Angew. Chem. 2008, 120, 9854; N. Takenaka, R. S.
Sarangthem, B. Captain, Angew. Chem., Int. Ed. 2008, 47, 9708.
[
[
18] E. Botek, J.-M. Andr e´ , B. Champagne, T. Verbiest, A. Persoons, J. Chem. Phys. 2005, 122, 234713.
19] A. Bossi, E. Licandro, S. Maiorana, C. Rigamonti, S. Righetto, G. R. Stephenson, M. Spassova, E.
Botek, B. Champagne, J. Phys. Chem. C 2008, 112, 7900.
[
20] T. R. Kelly, X. Cai, F. Damkaci, S. B. Panicker, B. Tu, S. M. Bushell, I. Cornella, M. J. Piggott, R.
Salives, M. Cavero, Y. Zhao, S. Jasmin, J. Am. Chem. Soc. 2007, 129, 376.
[
[
21] L. Vyklick y´ , S. H. Eichhorn, T. J. Katz, Chem. Mater. 2003, 15, 3594.
22] T. Verbiest, S. Sioncke, A. Persoons, L. Vyklick y´ , T. J. Katz, Angew. Chem. 2002, 114, 4038; T.
Verbiest, S. Sioncke, A. Persoons, L. Vyklick y´ , T. J. Katz, Angew. Chem., Int. Ed. 2002, 41, 3882.
23] T. Katakura, T. Tanaka, K. Hirai, H. Kita, Jpn. Kokai Tokkyo Koho 2006, Jap. Pat. 2006339577, A
[
20061214.
[
[
24] F. B. Mallory, Organic Reactions 1984, 30, 1 – 456, and refs. cit. therein.
25] H. Meier in ꢂ Houben-Weyl: Methoden der organischen Chemieꢃ, Thieme Verlag, Stuttgart, 1975,
Vol. IV, 5a, p. 511.
[
[
[
[
26] B. Laundon, G. A. Morrison, J. Chem. Soc. C 1971, 1694.
27] L. Lin, B. Yang, T. J. Katz, M. K. Pointdexter, J. Org. Chem. 1991, 56, 3769.
28] H. R. Talele, A. R. Chaudhary, P. R. Patel, A. V. Bedekar, Arkivoc 2011, ix, 15.
29] T. Nakagaki, K. Shin-ichiro, A. Harano, T. Shimuyozu, Tetrahedron 2010, 66, 976, and refs. cit.
therein.
[30] R. J. Bushby, D. Gooding, J. Chem. Soc., Perkin Trans. 2 1998, 1069.
[31] G. Zagotto, M. Palumbo, E. Uriarte, L. Bonsignore, G. Delogu, G. Podda, Farmaco 1998, 53, 675.
[32] H. Meier, H. Kretzschmann, H. Kolshorn, J. Org. Chem. 1992, 57, 6847.
Received May 3, 2013