A convenient route to 2-hydroxy- and 2,15-dihydroxyhexahelicene

Article abstract of DOI:10.1002/ejoc.200700381

2-Hydroxy- and 2,15-dihydroxyhexahelicene were synthesised from simple benzene and naphthalene building blocks by intramolecular Co¹- or Ni⁰-catalysed [2+2+2] cycloisomerisation of CH₃O- substituted aromatic triynes. This

Full text of DOI:10.1002/ejoc.200700381

FULL PAPER
DOI: 10.1002/ejoc.200700381
A Convenient Route to 2-Hydroxy- and 2,15-Dihydroxyhexahelicene
[a]
[a]
[a]
[a]
[a]
ˇ
ˇ
Filip Teplý, Irena G. Stará,* Ivo Starý,* Adrian Kollárovic, Daniel Lustinec,
[a]
[a]
[a]
ˇ
Zuzana Krausová, David Saman, and Pavel Fiedler
Keywords: Alkynes / Arenes / Cyclotrimerisation / Fused-ring systems
2-Hydroxy- and 2,15-dihydroxyhexahelicene were synthe-
sised from simple benzene and naphthalene building blocks
by intramolecular CoI- or Ni0-catalysed [2+2+2] cycloiso-
merisation of CH3O-substituted aromatic triynes. This ap-
proach avoids vexing photodehydrocyclisation of stilbene-
type precursors, providing thus a useful alternative to classi-
cal procedures.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
previous syntheses of helicenes and related compounds.[6,7]
Now we show the method can be easily adapted to the al-
ternative preparation of hexahelicene alcohols 1 and 2.
Introduction
Helicenes as unique chiral three-dimensional aromatics
have attracted continuous attention for decades.[1] In spite
of this, recently there have been only scattered efforts to
exploit helicenes in enantioselective catalysis.[2] Reetz’s
HELIXOL, 2,15-dihydroxyhexahelicene 1, was expected to
play an important role in this arena,[3] but only its use as
an excellent enantioselective fluorescent sensor has been
published so far.[4b] For broader exploitation of helically
chiral ligand 1 and its congener 2,[5] they should be access-
ible in a convenient way. Note, en route to 1 the key photo-
dehydrocyclisation of a stilbene-type precursor requires im-
practical high dilution conditions and provides rather low
yield owing to its incompleteness and some side product
formation.[3,4] The synthesis of 2 has never been described
in detail (Figure 1).
Results and Discussion
The convergent synthesis of diol 1 relies on the utilisation
of CH3O-substituted benzene and naphthalene building
blocks and de novo construction of three centrally fused
benzene rings. First, we carried out a simple preparation of
5 (Scheme 1). Radical bromination of 3 with NBS provided
known 4 in high yield.[8] Note, bromide 4 is very unstable
even in a pure state. However, when treated immediately
after its separation with LiCH2CϵCTIPS, the building
block 5 was produced in good yield.
Scheme 1. Synthesis of the benzene building block 5. Reagents and
conditions: (a) NBS (1.1 equiv.), AIBN (cat.), K2CO3 (cat.), CCl4,
reflux, 1 h, 99%; (b) LiCH2CϵCTIPS (1.0 equiv.), THF, –78 °C,
10 min, 74%.
Figure 1. 2-Hydroxy- and 2,15-dihydroxyhexahelicene.
In this paper, we report a new method to synthesise 1
and 2 by using intramolecular transition-metal catalysed
[2+2+2] cycloisomerisation of CH3O-substituted aromatic
triynes that circumvents disputed photochemistry. The basis
of this organometallic approach has been established by our
As only a limited set of trisubstituted naphthalenes is
commercially available, we had to prepare 14 from known 6
(Scheme 2).[9] To displace the hydroxy group with a carbon
moiety, we initially treated 6 with n-butyllithium/triflic an-
hydride to obtain reactive triflate 7. Attempts to regioselec-
tively introduce a bromomethyl group by NiII-catalysed
coupling[10] of 7 with CH3MgBr followed by radical bromi-
nation totally failed due to a complex mixture formed in
the first step. Therefore, we turned our attention to an alter-
native PdII-catalysed methoxycarbonylation route[11] of 7 to
distinguish between the Br and TfO groups. Indeed, the
more reactive TfO group was preferentially transformed
[a] Institute of Organic Chemistry and Biochemistry, Academy of
Sciences of the Czech Republic,
Flemingovo n. 2, 16610 Prague 6, Czech Republic
Fax: +420-220-183-133
E-mail: stara@uochb.cas.cz
stary@uochb.cas.cz
Supporting information for this article is available on the
WWW under http://www.eurjoc.org or from the author.
4244
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 4244–4250

A Convenient Route to 2-Hydroxy- and 2,15-Dihydroxyhexahelicene
FULL PAPER
[13]
into 8 in acceptable yield. Clean reduction with lithium alu- cene backbone, 17 reacted with Ph3CBF4 to give known
minium hydride without any debromination provided 18 in high yield.[4a,14,15] An alternative aromatisation of 17
alcohol 9 in high yield that was easily converted to bromide with triphenylmethanol in trifluoroacetic acid[16] heated at
10 in good yield on reaction with PBr3. Similarly as for 5, reflux was similarly efficient (69% yield). The removal of
the side arm in 11 was attached by treatment of 10 with CH3 groups with BBr3 completed the whole reaction se-
LiCH2CϵCTIPS. To preclude any Heck-type participation quence to provide 1.
of the tethered acetylene unit in the following Sonogashira
coupling, bromide 11 was transformed to the more reactive
iodide 12 in good yield by a routine lithiation/iodination
protocol. Pd0/CuI-catalysed coupling of 12 with trimethyl-
silylacetylene afforded 13 in excellent yield. Finally, smooth
partial desilylation with sodium methoxide led to the de-
sired naphthalene building block 14 in quantitative yield.
Scheme 3. Synthesis of 2,15-dihydroxyhexahelicene 1. Reagents and
conditions: (a) 5 (1.0 equiv.), 14 (1.0 equiv.), Pd(PPh3)4 (5%), CuI
(10%), iPr2NH, 80 °C, 10 min, 79%; (b) nBu4NF (2.4 equiv.), THF,
r.t., 1 h, 84%; (c) CpCo(CO)2 (20%), PPh3 (40%), n-decane, halo-
gen lamp, 140 °C, 1 h, 56%; (d) Ni(cod)2 (20%), PPh3 (40%), THF,
r.t., 24 h, 53%; (e) Ph3CBF4 (3.0 equiv.), 1,2-dichloroethane, 85 °C,
12 h, 64%; (f) BBr3 (10 equiv.), CH2Cl2, 0 °C to r.t., 2 h, 52%.
As a logical extension, we prepared monohydroxy deriva-
tive 2. By simply following the synthetic scheme for 1, the
preparation of 2 demonstrated an advantageous modular
Scheme 2. Synthesis of the naphthalene building block 14. Rea-
gents and conditions: (a) nBuLi (1.0 equiv.), THF, –78 °C, 5 min,
then Tf2O (1.3 equiv.), –78 °C, 40 min, 67%; (b) CO, Pd(OAc)2
(5%), dppp (5%), Et3N (2.5 equiv.), DMSO/CH3OH, 3:2, 70 °C,
2 h, 58%; (c) LiAlH4 (0.6 equiv.), THF, 0 °C, 1 h, 90%; (d) PBr3
(1.3 equiv.), THF, 0 °C, 2.5 h, 67%; (e) LiCH2CϵCTIPS
(1.0 equiv.), THF, –78 °C, 1 h, 77%; (f) nBuLi (1.1 equiv.), THF,
–78 °C, 10 min, then I2 (1.5 equiv.), –78 °C, 20 min, 95%; (g)
TMSCϵCH (1.6 equiv.), Pd(PPh3)4 (5%), CuI (10%), iPr2NH, in
a sealed tube, 80 °C, 1 h, 99%; (h) CH3ONa (2.4 equiv.), CH3OH,
r.t., 2 h, 99%.
Having obtained both the key building blocks 5 and 14,
we could complete the convergent synthesis of
1
(Scheme 3). First, we carried out Sonogashira coupling of
5 and 14 to receive triyne 15 in good yield. Subsequent desi-
lylation with nBu4NF provided unprotected triyne 16,
which was a suitable substrate for the key [2+2+2] cycloiso-
merisation reaction. Indeed, under CoI catalysis, tetra-
hydrohelicene 17 was produced in reasonable yield. It
should be noted that halogen lamp irradiation and the ad-
dition of triphenylphosphane were not essential, but the
former promoted the reaction through catalyst activation
and the latter kept the active catalyst alive for a longer
period.[12] Alternatively, Ni0-catalysed cyclisation led to an
Scheme 4. Synthesis of 2-hydroxyhexahelicene 2. Reagents and con-
ditions: (a) 5 (1.0 equiv.), 19 (1.0 equiv.), Pd(PPh3)4 (2.5%), CuI
(5%), iPr2NH, 80 °C, 10 min, 86%; (b) nBu4NF (2.4 equiv.), THF,
r.t., 1 h, 60%; (c) CpCo(CO)2 (20%), PPh3 (40%), n-decane, halo-
gen lamp, 140 °C, 3 h, 77%; (d) Ph3CBF4 (3.0 equiv.), 1,2-dichloro-
ethane, 80 °C, 3 h, 96%; (e) BBr3 (4.5 equiv.), CH2Cl2, r.t., 1 h,
almost identical yield of 17. To obtain a fully aromatic heli- 95%.
Eur. J. Org. Chem. 2007, 4244–4250
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I. G. Stará, I. Starý et al.
FULL PAPER
due was chromatographed on silica gel (petroleum ether/ethyl ace-
tate, 75:25) to afford 1 (32 mg, 52%) as an amorphous solid. 1H
NMR, 13C NMR and HR EI MS spectra were in agreement with
the literature data.[4] MS (EI): m/z (%) = 360 (29) [M]+·, 340 (11),
243 (3), 149 (11), 97 (23), 83 (35), 69 (48), 57 (99), 41 (100).
characteristic of our general methodology. Thus, iodide 5
was coupled with naphthyl acetylene[7] 19 under Pd0/CuI
catalysis to easily produce protected triyne 20 in high yield
(Scheme 4). After desilylation with nBu4NF, triyne 21 was
produced in acceptable yield. The key CoI-catalysed cyclo-
isomerisation furnished CH3O-substituted tetrahydrohel-
icene 22 in good yield. To accomplish the whole synthetic
sequence, the last two steps were executed. Both the aroma-
tisation with Ph3CBF4 to afford known[14] 23 and the subse-
quent demethylation with BBr3 to afford final 2 proceeded
well and rendered the products in excellent yields.
2-Hexahelicenol (2): A Schlenk flask was charged with methyl ether
23 (137 mg, 0.382 mmol) and flushed with argon. The material was
dissolved in dichloromethane (10 mL) and BBr3 (1.0  in dichloro-
methane, 1.70 mL, 1.70 mmol, 4.5 equiv.) was added dropwise. The
mixture was stirred at r.t. for 1 h. The mixture was diluted with
water (10 mL), extracted with dichloromethane (3ϫ20 mL), the
combined organic portions were dried with anhydrous Na2SO4 and
the solvent was evaporated in vacuo. The residue was chromato-
graphed on silica gel (petroleum ether/diethyl ether/acetone,
80:10:10) to afford 2 (125 mg, 95%) as an amorphous solid. 1H
NMR (500 MHz, CDCl3): δ = 6.75 (ddd, J = 8.5, 6.8, 1.4 Hz, 1
H), 6.83 (dd, J = 8.6, 2.5 Hz, 1 H), 6.92 (dt, J = 2.5, 0.7, 0.7 Hz,
1 H), 7.29 (ddd, J = 8.0, 6.8, 1.1 Hz, 1 H), 7.66 (ddt, J = 8.5, 1.1,
0.7, 0.7 Hz, 1 H), 7.73 (dt, J = 8.6, 0.5, 0.5 Hz, 1 H), 7.80 (d, J =
8.5 Hz, 1 H), 7.82 (ddd, J = 8.0, 1.4, 0.5 Hz, 1 H), 7.86 (dt, J =
8.5, 0.6, 0.6 Hz, 1 H), 7.91 (br. dd, J = 8.6, 0.5 Hz, 1 H), 7.93 (d,
J = 8.6 Hz, 1 H), 7.96 (d, J = 8.2 Hz, 2 H), 7.98 (dd, J = 8.2,
0.4 Hz, 1 H), 8.00 (dd, J = 8.2, 0.4 Hz, 1 H) ppm. 13C NMR
(125.7 MHz, CDCl3): δ = 111.58 (d), 115.95 (d), 123.87 (d), 124.20
(s), 124.78 (d), 125.93 (d), 126.34 (d), 126.85 (s), 126. 98 (d), 127.00
(d), 127.01 (d), 127.22 (d), 127.36 (d), 127.37 (d), 127.51 (s), 127.62
(d), 127.73 (d), 129.39 (d), 130.04 (s), 131.28 (s), 131.30 (s), 131.56
Conclusions
A new method was developed for the preparation of 2-hy-
droxy- and 2,15-dihydroxyhexahelicene 1 and 2, respectively,
from simple building blocks. The significance of the current
investigation is that it provides a useful alternative to the clas-
sic photochemistry-based approach, which has hindered
broader exploitation of 2-substituted hexahelicenes.
Experimental Section
General Remarks: 1H and 13C NMR spectra were recorded with
TMS as an internal standard. HMBC experiments were set up for
JC,H = 5 Hz. For the correct assignment of both 1H and 13C NMR
spectra of key compounds, the COSY, ROESY, HMQC, HMBC
and CIGAR-HMBC experiments were performed. For all the other
compounds, the general semiempirical equations were applied to
the chemical shift assignments. Electron impact (EI) mass spectra
were determined at an ionising voltage of 70 eV. Fast atom bom-
bardment (FAB) mass spectra were measured by using the thiogly-
cerol/glycerol 3:1 matrix or bis(2-hydroxyethyl) disulfide matrix.
HRMS spectra were obtained by the EI or FAB technique. Com-
pounds 6[9] and 19[7] were prepared according to the literature pro-
cedure. Commercially available reagent grade materials were used
as received. Solid Ni(cod)2 was handled in a glove box. Decane and
diisopropylamine were degassed by three freeze–pump–thaw cycles
before use; 1,4-dichloroethane and dichloromethane were distilled
from calcium hydride under an atmosphere of argon before use;
DMSO was distilled from calcium hydride under vacuum and
stored over 5 Å molecular sieves; THF was freshly distilled from
sodium/benzophenone under an atmosphere of nitrogen; tetrachlo-
romethane was filtered through alumina before use; methanol was
distilled with sodium under an atmosphere of nitrogen and stored
over 5 Å molecular sieves. TLC was performed on Silica gel 60
(s), 131.85 (s), 132.95 (s), 153.11 (s) ppm. IR (CHCl ): ν = 3592
˜
3
(m), 1623 (m), 1612 (m), 1585 (vw), 1558 (vw), 1531 (w), 1526 (w),
1507 (w), 1477 (w), 1416 (w), 1182 (m), 851 (s), 841 (vs) cm–1. MS
(EI): m/z (%) = 344 (100) [M]+·, 326 (24), 313 (23), 300 (45), 287
(11), 163 (15), 150 (17), 95 (12), 83 (14), 69 (18), 57 (26), 43 (24).
HRMS (EI): calcd. for C26H16O 344.1201; found 344.1187.
1-(Bromomethyl)-2-iodo-4-methoxybenzene (4): 5-Methoxy-2-meth-
ylaniline (5.0 g, 36.45 mmol) was dissolved in concentrated sulfuric
acid (8.0 mL) and water (120 mL). The solution was cooled to 0 °C
(measured with an internal thermometer), and the anilinium salt
precipitated. Sodium nitrite (2.67 g, 38.70 mmol, 1.06 equiv.) in
water (8 mL) was added dropwise under vigorous stirring at such
a rate to maintain a temperature between 0–5 °C. The resulting
orange-brown solution was treated with potassium iodide (6.07 g,
36.56 mmol, 1.0 equiv.) in water (8 mL) at r.t. for 1 h while nitrogen
evolution was observed. Then the mixture was stirred at 100 °C for
an additional 1 h until the nitrogen evolution deceased. The reac-
tion mixture was extracted with dichloromethane (3ϫ50 mL), and
the organic portions were combined, washed with aqueous KHCO3
(4ϫ), aqueous Na2S2O3 (5ϫ), water (1ϫ) and dried with anhy-
drous Na2SO4. The solvent was removed in vacuo, and the residue
was filtered through a short pad of silica gel (petroleum ether/di-
ethyl ether, 95:5) to afford iodide 3 (6.77 g, 75%) as a yellow orange
F254-coated aluminium sheets (Merck) and spots were detected by
the solution of Ce(SO4)2. 4 H2O (1%) and H3P(Mo3O10)4 (2%) in
sulfuric acid (10%). Flash chromatography was performed on Silica
gel 60 (0.040–0.063 mm or Ͻ0.063 mm, Merck) or on Biotage KP-
Sil Silica cartridges (0.040–0.063 mm) used in Horizon HPFC sys-
tem (Biotage, Inc.).
1
oil. H NMR (200 MHz, CDCl3): δ = 2.36 (s, 3 H), 3.76 (s, 3 H),
6.80 (dd, J = 8.2, 2.6 Hz, 1 H), 7.11 (d, J = 8.2 Hz, 1 H), 7.35 (d,
J
= 2.6 Hz, 1 H) ppm. The mixture of iodide 3 (3.95 g,
15.92 mmol), N-bromosuccinimide (3.12 g, 17.53 mmol, 1.1 equiv.)
and catalytic amounts of AIBN and K2CO3 in tetrachloromethane
(100 mL) was heated to reflux for 1 h with use of an IR lamp. The
precipitate was filtered off, washed with tetrachloromethane and
the portions were combined. The solvent was evaporated in vacuo,
and the residue was quickly filtered through a short pad of silica
gel (petroleum ether/diethyl ether, 90:10) to receive bromide 4
2,15-Hexahelicenediol (1): A Schlenk flask was charged with di-
methoxy derivative 18 (66 mg, 0.170 mmol) and flushed with argon.
The material was dissolved in dichloromethane (10 mL) and BBr3
(1.0  in dichloromethane, 1.70 mL, 1.70 mmol, 10.0 equiv.) was
added dropwise. The mixture was stirred at r.t. for 1 h. The mixture
was diluted with water (10 mL), extracted with dichloromethane (5.15 g, 99%) as an amorphous solid.[8] The substance was immedi-
(3ϫ10 mL), the combined organic portions were dried with anhy-
drous Na2SO4 and the solvent was evaporated in vacuo. The resi-
ately used owing to its instability (it may rapidly darken during the
evaporation of the solvent and evolve fumes but these changes may
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Eur. J. Org. Chem. 2007, 4244–4250

A Convenient Route to 2-Hydroxy- and 2,15-Dihydroxyhexahelicene
FULL PAPER
not influence the next reaction with organolithium). 1H NMR
(200 MHz, CDCl3): δ = 3.80 (s, 3 H), 4.61 (s, 2 H), 6.88 (dd, J =
(708 mg, 1.72 mmol, 5 mol-%) and flushed with argon. Methanol
(200 mL) with triethylamine (12 mL, 86.10 mmol, 2.5 equiv.) were
8.6, 2.4 Hz, 1 H), 7.38 (d, J = 8.6 Hz, 1 H), 7.39 (d, J = 2.4 Hz, 1 added to the reaction mixture. Triflate 7 (12.0 g, 34.37 mmol) in
H) ppm. IR: ν = 3084 (w), 3064 (w), 2839 (m), 1595 (vs), 1565 (s),
DMSO (300 mL) was added, and the mixture was stirred at 70 °C
for 2 h while carbon monoxide was slowly bubbled throughout the
solution. The reaction mixture was diluted with water and ex-
tracted with diethyl ether (4ϫ80 mL). Ethereal portions were com-
˜
1492 (vs), 1464 (s), 1439 (s), 1342 (w), 1309 (s), 1201 (s), 1182 (s),
1022 (vs), 611 (m) cm–1. MS (EI): m/z (%) = 328 (4) [M]+· with
81Br, 326 (5) [M]+· with 79Br, 262 (12), 247 (100), 201 (5), 199 (6),
120 (18), 105 (7), 91 (8), 77 (11), 63 (8), 51 (15), 41 (13). HRMS bined, washed with water and dried with anhydrous Na2SO4. The
(EI): calcd. for C8H879BrIO 325.8803; found 325.8811.
solvents were removed in vacuo, and the residue was chromato-
graphed on silica gel (petroleum ether/diethyl ether/acetone, 90:10:0
to 80:10:10) to provide methyl ester 8 (5.86 g, 58%) as an oil. H
NMR (500 MHz, CDCl3): δ = 3.99 (s, 3 H), 4.00 (s, 3 H), 7.25 (dd,
J = 8.9, 2.5 Hz, 1 H), 7.54 (d, J = 8.4 Hz, 1 H), 7.72 (d, J = 2.5 Hz,
1 H), 7.74 (d, J = 8.9 Hz, 1 H), 7.76 (br. d, J = 8.4 Hz, 1 H) ppm.
13C NMR (125.7 MHz, CDCl3): δ = 52.66 (q), 55.48 (q), 106.61
(d), 120.87 (s), 121.09 (d), 123.49 (d), 127.47 (d), 129.80 (d), 130.61
(s), 131.72 (s), 133.69 (s), 159.48 (s), 168.05 (s) ppm. IR (CHCl3):
[4-(2-Iodo-4-methoxyphenyl)-1-butynyl](triisopropyl)silane (5): n-
Butyllithium (1.6  in hexanes, 10.40 mL, 16.64 mmol, 1.05 equiv.)
was added dropwise to a solution of triisopropyl(prop-1-yn-1-yl)-
silane (4.0 mL, 16.70 mmol, 1.06 equiv.) in THF (60 mL) at –78 °C
under an atmosphere of argon. After the mixture was stirred at
–78 °C for 1.5 h, bromide 4 (5.18 g, 15.84 mmol) in THF (20 mL)
was added dropwise. The mixture was stirred at –78 °C for 10 min
and then warmed to r.t. The solvents were removed in vacuo. Flash
chromatography on silica gel (petroleum ether/diethyl ether, 99:1)
gave alkyne 5 (5.22 g, 74%) as an oil. 1H NMR (500 MHz, CDCl3):
δ = 0.98–1.06 (m, 21 H), 2.52 (t, J = 7.3 Hz, 2 H), 2.89 (t, J =
7.3 Hz, 2 H), 3.76 (s, 3 H), 6.81 (dd, J = 8.4, 2.7 Hz, 1 H), 7.20 (d,
J = 8.4 Hz, 1 H), 7.34 (d, J = 2.7 Hz, 1 H) ppm. 13C NMR
(125.7 MHz, CDCl3): δ = 11.27 (d), 18.61 (q), 20.79 (t), 38.93 (t),
55.49 (q), 81.25 (s), 99.95 (s), 107.58 (s), 114.26 (d), 124.34 (d),
1
ν = 3067 (w), 1729 [vs (br)], 1626 (vs), 1603 (s), 1557 (m), 1510
˜
(vs), 1443 (vs), 1434 [s (sh)], 1384 (s), 1273 (s), 1247 (vs), 1034 (s),
975 (m), 865 (w), 845 (vs), 528 (m) cm–1. MS (EI): m/z (%) = 296
(98) [M]+· with 81Br, 294 (100) [M]+· with 79Br, 265 (51), 263 (56),
237 (16), 235 (18), 222 (9), 220 (9), 216 (33), 196 (7), 194 (7), 185
(22), 156 (25), 113 (33), 97 (16), 81 (25), 69 (52), 57 (41), 43 (57).
HRMS (EI): calcd. for C13H1179BrO3 293.9892; found 293.9879.
130.14 (d), 135.08 (s), 158.31 (s) ppm. IR (CHCl ): ν = 2959 (s),
˜
3
(1-Bromo-7-methoxy-2-naphthyl)methanol (9): Lithium aluminium
hydride (1.0  in THF, 17.0 mL, 17.0 mmol, 0.6 equiv.) was added
dropwise to methyl ester 8 (8.21 g, 27.82 mmol) in THF (160 mL)
under an atmosphere of argon, and the mixture was stirred at 0 °C
for 1 h. Then anhydrous Na2SO4 (10 g) was added, and the excess
hydride was decomposed by the careful addition of a saturated
solution of Na2SO4 in water. The reaction mixture was filtered
through a short pad of silica gel (ether), and the solvents were
removed in vacuo to provide pure alcohol 9 (6.66 g, 90%) as an
amorphous solid. 1H NMR (500 MHz, CDCl3): δ = 2.06 (t, J =
6.0 Hz, 1 H), 3.98 (s, 3 H), 4.97 (J = 6.0 Hz, 2 H), 7.18 (dd, J =
8.9, 2.5 Hz, 1 H), 7.49 (d, J = 8.3 Hz, 1 H), 7.59 (d, J = 2.5 Hz, 1
H), 7.73 (d, J = 8.9 Hz, 1 H), 7.76 (br. d, J = 8.3 Hz, 1 H) ppm.
13C NMR (125.7 MHz, CDCl3): δ = 55.43 (q), 66.11 (t), 105.34 (d),
119.42 (d), 121.15 (s), 123.70 (d), 127.68 (d), 129.51 (s), 129.82 (d),
2944 (s), 2865 (s), 2839 (s), 2170 (m), 1599 (s), 1563 (m), 1491 (s),
1464 (s), 1441 (m), 1428 (w), 1383 (w), 1366 (w), 1336 (w), 1323
(w), 1313 (w), 1286 (m), 1182 (w), 1159 (w), 1072 (w), 1062 (w),
1021 (s), 996 (m), 920 (w), 884 (w), 678 (m) cm–1. MS (EI): m/z
(%) = 442 (1) [M]+·, 399 (100), 371 (9), 357 (10), 273 (6), 247 (18),
229 (17), 201 (10), 153 (17), 121 (7), 97 (9), 83 (12), 73 (6), 59 (12).
MS [FAB, bis(2-hydroxyethyl) disulfide]: m/z (%) = 399 [M –
C3H7]+, 371, 357, 343, 328, 273, 246, 229, 215, 201, 187, 171, 121,
87.
1-Bromo-7-methoxy-2-naphthyl Trifluoromethanesulfonate (7): n-
Butyllithium (1.6  in hexanes, 35 mL, 56.0 mmol, 1.0 equiv.) was
added dropwise to alcohol 6 (14.21 g, 56.15 mmol)[9] in THF
(360 mL) under an atmosphere of argon, and the mixture was
stirred at –78 °C for 5 min. Triflic anhydride (12.0 mL, 71.33 mmol,
1.3 equiv.) was added dropwise, and the reaction mixture was
stirred at –78 °C for 40 min. To prevent decomposition of the prod-
uct, triethylamine (12 mL, 86.10 mmol, 1.5 equiv.) was added, and
the reaction mixture was allowed to reach r.t. The solvents were
removed in vacuo, and the residue was chromatographed on alu-
mina (petroleum ether/diethyl ether/acetone, 80:10:10) to obtain
133.53 (s), 138.25 (s), 159.13 (s) ppm. IR (CHCl ): ν = 3608 (m),
˜
3
3461 (w), 3066 (w), 2841 (w), 1627 (vs), 1603 (m), 1559 (w), 1512
(vs), 1461 (s), 1414 (w), 1381 (s), 1313 (m), 1263 (s), 1034 (s), 842
(vs), 527 (m) cm–1. MS (EI): m/z (%) = 268 (95) [M]+· with 81Br,
266 (100) [M]+· with 79Br, 256 (9), 188 (32), 158 (36), 144 (53), 127
(25), 115 (48), 93 (12), 69 (10), 57 (16), 43 (19). HRMS (EI): calcd.
for C12H1179BrO 265.9942; found 265.9938.
1
triflate 7 (13.06 g, 67%) as an oil. H NMR (500 MHz, CDCl3): δ
= 3.98 (s, 3 H), 7.23 (dd, J = 8.9, 2.5 Hz, 1 H), 7.28 (d, J = 8.9 Hz,
1 H), 7.54 (d, J = 2.5 Hz, 1 H), 7.75 (d, J = 8.9 Hz, 1 H), 7.78 (br.
d, J = 8.9 Hz, 1 H) ppm. 13C NMR (125.7 MHz, CDCl3): δ = 55.54
(q), 105.88 (d), 114.55 (s), 117.28 (d), 118.68 (q, JC,F = 320.5 Hz),
120.71 (d), 128.35 (s), 129.23 (d), 129.98 (d), 134.29 (s), 145.59 (s),
1-Bromo-2-(bromomethyl)-7-methoxynaphthalene (10): Phosphorus
tribromide (1.20 mL, 12.63 mmol, 1.3 equiv.) was added dropwise
to alcohol 9 (7.86 g, 29.43 mmol) in THF (200 mL) under an atmo-
sphere of argon, and the mixture was stirred at 0 °C for 2.5 h. The
solvent was evaporated in vacuo, and the residue was chromato-
graphed on silica gel (petroleum ether/diethyl ether, 90:10 to 80:20)
to furnish bromide 10 (6.49 g, 67%) as an amorphous solid. 1H
NMR (500 MHz, CDCl3): δ = 3.98 (s, 3 H), 4.84 (s, 2 H), 7.19 (dd,
J = 8.9, 2.5 Hz, 1 H), 7.38 (d, J = 8.3 Hz, 1 H), 7.62 (d, J = 2.5 Hz,
1 H), 7.71 (d, J = 8.9 Hz, 1 H), 7.71 (d, J = 8.3 Hz, 1 H) ppm. 13C
NMR (125.7 MHz, CDCl3): δ = 35.00 (t), 55.47 (q), 106.14 (d),
120.00 (d), 123.56 (s), 125.36 (d), 127.95 (d), 129.59 (s), 129.78 (d),
160.03 (s) ppm. IR (CHCl ): ν = 3070 (vw), 3009 (w), 2962 (w),
˜
3
2938 (w), 2910 (w), 2845 (vw), 2830 (vw), 1628 (s), 1599 (w), 1572
(w), 1507 (s), 1464 (m), 1460 (m), 1432 (vs), 1419 (s), 1384 (s), 1260
(m), 1228 (vs), 1217 (vs), 1189 (s), 1174 (s), 1142 (vs), 1036 (m),
991 (s), 978 (s), 867 (vs), 836 (s), 627 (s), 592 (s) cm–1. MS (EI):
m/z (%) = 386 (99) [M]+· with 81Br, 384 (98) [M]+· with 79Br, 253
(41), 351 (40), 225 (100), 223 (97), 210 (15), 208 (16), 182 (20), 180
(21), 172 (32), 160 (14), 157 (14), 129 (5), 113 (10), 101 (20), 75
(12), 69 (15), 63 (7), 51 (7). HRMS (EI): calcd. for C12H879BrF3O4S
383.9279; found 383.9280.
133.91 (s), 135.40 (s), 159.35 (s) ppm. IR (CHCl ): ν = 3064 (w),
˜
3
2840 (w), 1625 (vs), 1601 (m), 1559 (m), 1512 (vs), 1460 (vs), 1413
(m), 1382 (s), 1317 (m), 1263 (vs), 1034 (s), 841 (vs), 657 (m), 628
(m), 527 (m) cm–1. MS (EI): m/z (%) = 332 (15) [M]+· with 81Br/
81Br, 330 (31) [M]+· with 79Br/81Br, 328 (16) [M]+· with 79Br/79Br,
Methyl 1-Bromo-7-methoxy-2-naphthoate (8): A Schlenk flask was
charged with Pd(OAc)2 (385 mg, 1.72 mmol, 5 mol-%) and dppp
Eur. J. Org. Chem. 2007, 4244–4250
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4247

I. G. Stará, I. Starý et al.
FULL PAPER
251 (98), 249 (100), 208 (8), 206 (10), 171 (35), 155 (18), 139 (9),
(3ϫ10 mL). The combined fractions were evaporated to dryness in
127 (33), 98 (14), 83 (15), 69 (23), 57 (34), 55 (29), 43 (33). HRMS vacuo, and the residue was chromatographed on a short pad of silica
(EI): calcd. for C12H1079Br2O 327.9098; found 327.9110.
gel (petroleum ether/diethyl ether, 99:1) to obtain 13 (1.63 g, 99%) as
an oil. 1H NMR (500 MHz, CDCl3): δ = 0.34 (s, 9 H), 0.99–1.06 (m,
21 H), 2.66 (t, J = 7.7 Hz, 2 H), 3.21 (t, J = 7.7 Hz, 2 H), 3.95 (s, 3
H), 7.12 (dd, J = 8.8, 2.5 Hz, 1 H), 7.26 (d, J = 8.5 Hz, 1 H), 7.66
(br. d, J = 2.5 Hz, 1 H), 7.68 (d, J = 8.5 Hz, 1 H) ppm. 13C NMR
(125.7 MHz, CDCl3): δ = 0.14 (q), 11.28 (d), 18.60 (q), 20.89 (t),
35.09 (t), 55.14 (q), 80.76 (s), 101.70 (s), 104.11 (s), 104.48 (d), 108.26
(s), 117.93 (s), 118.40 (d), 125.01 (d), 127.31 (s), 128.18 (d), 129.55
[4-(1-Bromo-7-methoxy-2-naphthyl)-1-butynyl](triisopropyl)silane
(11): n-Butyllithium (1.6  in hexanes, 18.0 mL, 28.8 mmol,
1.06 equiv.) was added dropwise to a solution of triisopropyl(prop-
1-yn-1-yl)silane (6.90 mL, 28.81 mmol, 1.06 equiv.) in THF
(80 mL) at –78 °C under an atmosphere of argon. After the mixture
was stirred at –78 °C for 2 h, bromide 10 (8.93 g, 27.06 mmol) in
THF (120 mL) was added dropwise. The mixture was stirred at
–78 °C for 1 h and then warmed to r.t. The solvents were removed
in vacuo. Flash chromatography on silica gel (petroleum ether) gave
(d), 135.13 (s), 142.68 (s), 158.62 (s) ppm. IR (CHCl ): ν = 3053 (w),
˜
3
2865 (s), 2170 (m), 2146 (w), 1623 (s), 1598 (w), 1570 (w), 1511 (m),
1462 (s), 1388 (w), 1367 (w), 1251 (s), 1072 (w), 1032 (m), 996 (w),
884 (m), 853 (vs), 843 (vs), 678 (m) cm–1. MS (EI): m/z (%) = 462
(100) [M]+·, 447 (7), 419 (93), 389 (6), 379 (11), 345 (10), 319 (11),
290 (8), 275 (22), 251 (10), 219 (8), 158 (11), 115 (14), 101 (10), 87
(15), 73 (67), 59 (41), 45 (6). HRMS (EI): calcd. for C29H42OSi2
462.2774; found 462.2772.
1
alkyne 11 (9.29 g, 77%) as an oil. H NMR (500 MHz, CDCl3): δ
= 0.98–1.07 (m, 21 H), 2.66 (t, J = 7.3 Hz, 2 H), 3.20 (t, J = 7.3 Hz,
2 H), 3.97 (s, 3 H), 7.14 (dd, J = 8.9, 2.6 Hz, 1 H), 7.30 (d, J =
8.2 Hz, 1 H), 7.61 (d, J = 2.6 Hz, 1 H), 7.61 (d, J = 8.2 Hz, 1 H),
7.69 (d, 1 H, 8.9) ppm. 13C NMR (125.7 MHz, CDCl3): δ = 11.29
(d), 18.59 (q), 20.39 (t), 36.87 (t), 55.41 (q), 81.29 (s), 105.82 (d),
107.66 (s), 118.72 (d), 122.57 (s), 126.15 (d), 127.11 (d), 128.84 (s),
[4-(1-Ethynyl-7-methoxy-2-naphthyl)-1-butynyl](triisopropyl)silane
(14): Sodium methoxide generated from sodium (277 mg,
12.04 mmol, 2.4 equiv.) and methanol (10 mL) was added to TMS
derivative 13 (2.32 g, 5.01 mmol) in methanol (20 mL) under an
atmosphere of argon, and the mixture was stirred at r.t. for 2 h.
The solution was evaporated in vacuo to dryness, and the residue
was chromatographed on silica gel (petroleum ether/diethyl ether,
99:1 to 90:10) to afford 14 (1.94 g, 99 %) as an oil. 1H NMR
(500 MHz, CDCl3): δ = 0.99–1.06 (m, 21 H), 2.68 (t, J = 7.4 Hz, 2
H), 3.23 (t, J = 7.4 Hz, 2 H), 3.71 (s, 1 H), 3.96 (s, 3 H), 7.13 (dd,
J = 9.0, 2.6 Hz, 1 H), 7.30 (d, J = 8.4 Hz, 1 H), 7.65 (d, 1 H, 2.6),
7.68 (d, J = 8.4 Hz, 1 H), 7.70 (d, J = 9.0 Hz, 1 H) ppm. 13C NMR
(125.7 MHz, CDCl3): δ = 11.28 (d), 18.58 (q), 21.00 (t), 34.61 (t),
55.33 (q), 80.26 (s), 81.06 (s), 86.29 (d), 104.34 (d), 108.07 (s),
116.89 (s), 118.50 (d), 125.07 (d), 127.29 (s), 128.43 (d), 129.59 (d),
129.65 (d), 133.81 (s), 138.55 (s), 158.95 (s) ppm. IR (CHCl ): ν =
˜
3
3062 (w), 2866 (vs), 2171 (s), 1627 (s), 1603 (m), 1558 (w), 1512
(vs), 1461 (vs), 1412 (m), 1381 (s), 1367 (m), 1317 (m), 1261 (s),
1073 (w), 1035 (s), 996 (m), 884 (s), 838 (s), 678 (s), 660 (s), 624
(m), 618 (m), 526 (m) cm–1. MS (EI): m/z (%) = 446 (66) [M]+· with
81Br, 444 (65) [M]+· with 79Br, 403 (100), 401 (96), 366 (16), 347
(21), 323 (24), 305 (61), 279 (29), 263 (17), 251 (76), 237 (44), 274
(47), 265 (35), 139 (29), 96 (42), 89 (38), 73 (41), 59 (76), 43 (41).
HRMS (EI): calcd. for C24H3379BrOSi 444.1484; found 444.1497.
[4-(1-Iodo-7-methoxy-2-naphthyl)-1-butynyl](triisopropyl)silane (12):
n-Butyllithium (1.6  in hexanes, 7.0 mL, 11.20 mmol, 1.01 equiv.)
was added dropwise to a stirred solution of aryl bromide 11 (4.94 g,
11.10 mmol) in THF (100 mL) at –78 °C under an atmosphere of
argon. After the mixture was stirred at –78 °C for 20 min, iodine
(3.64 g, 14.40 mmol, 1.3 equiv.) in THF (20 mL) was added drop-
wise. The mixture was stirred at –78 °C for 30 min and then
warmed to r.t. The reaction mixture was evaporated to dryness in
vacuo, and the residue was diluted with dichloromethane (100 mL),
washed with water (1ϫ), Na2S2O3 (2ϫ), water (1ϫ) and dried with
anhydrous Na2SO4. The solvent was removed in vacuo, and the
residue was chromatographed on silica gel (petroleum ether) to af-
135.32 (s), 143.10 (s), 158.75 (s) ppm. IR (CHCl ): ν = 3305 (m),
˜
3
3052 (w), 2865 (vs), 2170 (m), 2098 (w), 1624 (s), 1598 (w), 1571
(w), 1511 (m), 1462 (s), 1387 (m), 1367 (w), 1070 (w), 1030 (m),
996 (m), 883 (s), 678 (m), 660 (s), 610 (m) cm–1. MS (EI): m/z (%)
= 390 (100) [M]+·, 379 (20), 347 (42), 289 (23), 275 (21), 263 (49),
247 (14), 202 (20), 182 (23), 158 (20), 152 (28), 146 (21), 139 (18),
115 (31), 87 (14), 73 (38), 59 (43), 41 (11). HRMS (EI): calcd. for
C26H34OSi 390.2379; found 390.2391.
1
ford pure iodide 12 (3.34 g, 61%) as an oil. H NMR (500 MHz,
Triisopropyl{4-[4-methoxy-2-({7-methoxy-2-[4-(triisopropylsilyl)-3-
butynyl]-1-naphthyl}ethynyl)phenyl]-1-butynyl}silane (15): A
Schlenk flask was charged with phenyl iodide 5 (1.73 g, 3.91 mmol,
1.0 equiv.), Pd(PPh3)4 (113 mg, 0.098 mmol, 2.5 mol %), CuI
(37 mg, 0.194 mmol, 5 mol%) and flushed with argon. Diisopropyl-
amine (10 mL) and then naphthyl acetylene 14 (1.53 g, 3.92 mmol,
1.0 equiv.) in diisopropylamine (10 mL) were added, and the reac-
tion mixture was stirred at 80 °C for 15 min. The precipitate was
filtered off and washed with petroleum ether (5ϫ10 mL). The com-
bined fractions were evaporated to dryness in vacuo, and the resi-
due was chromatographed on silica gel (petroleum ether/diethyl
ether, 99:1) to obtain 15 (1.82 g, 66 %) as an oil. 1H NMR
(500 MHz, CDCl3): δ = 0.97–1.04 (m, 42 H), 2.71 (t, J = 7.2 Hz, 2
H), 2.75 (t, J = 7.4 Hz, 2 H), 3.18 (t, J = 7.2 Hz, 2 H), 3.29 (t, J =
7.4 Hz, 2 H), 3.83 (s, 3 H), 3.99 (s, 3 H), 6.86 (dd, J = 8.5, 2.8 Hz,
1 H), 7.14 (d, J = 2.8 Hz, 1 H), 7.14 (dd, J = 8.9, 2.5 Hz, 1 H),
7.29 (d, J = 8.5 Hz, 1 H), 7.34 (d, J = 8.3 Hz, 1 H), 7.68 (br. d, J
= 8.3 Hz, 1 H), 7.72 (d, J = 8.9 Hz, 1 H), 7.76 (d, J = 2.5 Hz, 1 H)
CDCl3): δ = 0.98–1.07 (m, 21 H), 2.65 (t, J = 7.4 Hz, 2 H), 3.24 (t,
J = 7.4 Hz, 2 H), 3.98 (s, 3 H), 7.12 (dd, J = 8.8, 2.6 Hz, 1 H), 7.31
(d, J = 8.2 Hz, 1 H), 7.58 (d, J = 2.6 Hz, 1 H), 7.64 (br. d, J =
8.2 Hz, 1 H), 7.66 (d, J = 8.8 Hz, 1 H) ppm. 13C NMR (125.7 MHz,
CDCl3): δ = 11.29 (q), 18.61 (q), 20.71 (t), 42.23 (t), 55.43 (q), 81.39
(s), 104.04 (s), 107.51 (s), 111.67 (d), 118.60 (d), 125.66 (d), 128.23
(d), 128.24 (s), 129.84 (d), 136.46 (s), 142.97 (s), 159.28 (s) ppm.
IR (CHCl ): ν = 3060 (w), 2866 (vs), 2170 (m), 1626 (vs), 1601 (w),
˜
3
1552 (w), 1511 (vs), 1460 (s), 1407 (w), 1377 (s), 1365 [w (sh)], 1315
(w), 1260 (s), 1035 (s), 1073 (w), 996 (m), 884 (s), 839 (s), 678 (s),
660 (s), 628 (m), 618 (m), 518 (m) cm–1. MS (EI): m/z (%) = 492
(56) [M]+·, 449 (100), 407 (12), 323 (14), 279 (23), 251 (24), 237
(26), 197 (36), 189 (19), 59 (19). HRMS (EI): calcd. for C24H33IOSi
492.1345; found 492.1352.
Triisopropyl(4-{7-methoxy-1-[(trimethylsilyl)ethynyl]-2-naphthyl}-1-
butynyl)silane (13): A teflon autoclave was charged with aryl iodide
12 (1.75 g, 3.55 mmol), Pd(PPh3)4 (205 mg, 0.177 mmol, 5 mol%)
and CuI (67 mg, 0.352 mmol, 10 mol%) and then flushed with argon. ppm. 13C NMR (125.7 MHz, CDCl3): δ = 11.29 (d), 18.57 (q),
Diisopropylamine (20 mL) and TMS-CϵCH (800 µL, 5.66 mmol,
1.6 equiv.) were added, and the reaction was stirred at 80 °C for 1 h.
The precipitate was filtered off and washed with petroleum ether
18.59 (q), 21.29 (t), 21.48 (t), 33.40 (t), 35.02 (t), 55.27 (q), 55.38
(q), 81.19 (s), 81.28 (s), 89.73 (s), 97.16 (s), 104.39 (d), 107.88 (s),
107.95 (s), 114.54 (d), 117.31 (d), 118.00 (s), 118.49 (d), 123.77 (s),
4248
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 4244–4250

A Convenient Route to 2-Hydroxy- and 2,15-Dihydroxyhexahelicene
125.30 (d), 127.49 (s), 128.12 (d), 129.65 (d), 130.57 (d), 134.37 (s),
FULL PAPER
(3), 277 (4), 261 (5), 196 (6), 171 (6), 127 (8), 69 (10) 57 (13), 43
(10). HRMS (EI): calcd. for C28H24O2 392.1776; found 392.1767.
135.05 (s), 142.07 (s), 157.97 (s), 158.67 (s) ppm. IR (CHCl ): ν =
˜
3
3053 (w), 2865 (vs), 2170 (m), 1623 (s), 1604 (m), 1569 (w), 1511
(m), 1500 (m), 1462 (s), 1426 (m), 1387 (w), 1383 (w), 1366 (w),
1316 (w), 1180 (w), 1176 (w), 1072 (w), 1038 (m), 996 (m), 883 (m),
678 (m) cm–1. MS (EI): m/z (%) = 704 (4) [M]+·, 661 (7), 462 (5),
399 (100), 353 (14), 323 (15), 271 (11), 229 (26), 201 (18), 149 (17),
115 (29), 87 (16), 59 (29). HRMS (EI): calcd. for C46H64O2Si2
704.4445; found 704.4462.
2,15-Dimethoxyhexahelicene (18): A solution of 17 (68 mg,
0.173 mmol) and Ph3CBF4 (170 mg, 0.515 mmol, 3.0 equiv.) in 1,2-
dichloroethane (6 mL) was stirred under an atmosphere of argon at
85 °C for 12 h. The solvent was removed in vacuo, and the residue
was chromatographed on silica gel (petroleum ether/diethyl ether,
1
95:5) to obtain 18 (57 mg, 85%) as an amorphous solid. H NMR
and 13C NMR spectra were in agreement with the literature data.[15]
2-(3-Butynyl)-1-{[2-(3-butynyl)-5-methoxyphenyl]ethynyl}-7-meth-
oxynaphthalene (16): Tetrabutylammonium fluoride (1.07  in
THF, 1.06 mL, 1.13 mmol, 2.5 equiv.) was added to silylated triyne
15 (320 mg, 0.454 mmol) in THF (15 mL) under an atmosphere of
argon, and the mixture was stirred at r.t. for 1 h. The solution was
evaporated in vacuo to dryness, and the residue was chromato-
graphed on silica gel (petroleum ether/diethyl ether, 95:5) to obtain
16 (178 mg, 99%) as an oil. 1H NMR (500 MHz, CDCl3): δ = 1.98
(t, J = 2.6 Hz, 1 H), 2.00 (t, J = 2.7 Hz, 1 H), 2.63 (dt, J = 7.5,
7.5, 2.6 Hz, 2 H), 2.68 (dt, J = 7.6, 7.6, 2.7 Hz, 2 H), 3.17 (t, J =
7.5 Hz, 2 H), 3.30 (t, J = 7.6 Hz, 2 H), 3.84 (s, 3 H), 4.00 (s, 3 H),
6.90 (dd, J = 8.5, 2.7 Hz, 1 H), 7.16 (dd, J = 8.8, 2.6 Hz, 1 H), 7.18
(d, J = 2.7 Hz, 1 H), 7.26 (d, J = 8.5 Hz, 1 H), 7.30 (d, J = 8.3 Hz,
1 H), 7.72 (br. d, J = 8.3 Hz, 1 H), 7.73 (d, J = 8.9 Hz, 1 H), 7.75
(br. d, J = 2.6 Hz, 1 H) ppm. 13C NMR (125.7 MHz, CDCl3): δ =
19.83 (t), 20.00 (t), 33.03 (t), 34.73 (t), 55.39 (q), 69.05 (d), 69.19
(d), 83.71 (s), 83.78 (s), 89.71 (s), 97.15 (s), 104.36 (d), 114.92 (d),
117.27 (d), 118.08 (s), 118.70 (d), 123.81 (s), 124.96 (d), 127.47 (s),
128.35 (d), 129.73 (d), 130.16 (d), 133.97 (s), 134.98 (s), 141.89 (s),
Triisopropyl{4-[4-methoxy-2-({2-[4-(triisopropylsilyl)-3-butynyl]-1-
naphthyl}ethynyl)phenyl]-1-butynyl}silane (20): A Schlenk flask was
charged with phenyl iodide 5 (2.06 g, 4.66 mmol, 1.0 equiv.),
Pd(PPh3)4 (135 mg, 0.117 mmol, 2.5 mol %) and CuI (44 mg,
0.231 mmol, 5 mol%) and flushed with argon. Diisopropylamine
(10 mL) and then naphthyl acetylene 19 (1.68 g, 4.66 mmol,
1.0 equiv.)[7] in diisopropylamine (8 mL) were added, and the reac-
tion mixture was stirred at 80 °C for 10 min. The precipitate was
filtered off and washed with petroleum ether (5ϫ10 mL). The com-
bined fractions were evaporated to dryness in vacuo, and the resi-
due was chromatographed on silica gel (petroleum ether/diethyl
1
ether, 99:1 to 95:5) to obtain 20 (2.70 g, 86%) as an oil. H NMR
(500 MHz, CDCl3): δ = 0.97–1.05 (m, 42 H), 2.71 (t, J = 7.3 Hz, 2
H), 2.75 (t, J = 7.3 Hz, 2 H), 3.13 (t, J = 7.3 Hz, 2 H), 3.31 (t, J =
7.3 Hz, 2 H), 3.85 (s, 3 H), 6.86 (dd, J = 8.5, 2.8 Hz, 1 H), 7.17 (d,
J = 2.8 Hz, 1 H), 7.29 (d, J = 8.5 Hz, 1 H), 7.48 (ddd, J = 8.1, 6.7,
1.2 Hz, 1 H), 7.49 (d, J = 8.5 Hz, 1 H), 7.58 (ddd, J = 8.3, 6.7,
1.4 Hz, 1 H), 7.76 (d, J = 8.5 Hz, 1 H), 7.83 (dt, J = 8.1, 1.4, 0.7,
0.7 Hz, 1 H), 8.42 (ddt, J = 8.4, 1.2, 0.8, 0.8 Hz, 1 H) ppm. 13C
NMR (125.7 MHz, CDCl3): δ = 11.27 (d), 11.29 (d), 18.58 (q),
18.61 (q), 21.30 (t), 21.54 (t), 33.51 (t), 34.86 (t), 55.47 (q), 81.10
(s), 81.27 (s), 89.40 (s), 97.19 (s), 107.84 (s), 108.01 (s), 114.74 (s),
117.29 (d), 119.24 (s), 123.61 (s), 125.75 (d), 126.00 (d), 126.87 (d),
127.61 (d), 128.11 (d), 128.32 (d), 130.58 (d), 132.01 (s), 133.58 (s),
158.00 (s), 158.79 (s) ppm. IR (CHCl ): ν = 3307 (s), 3052 (w),
˜
3
2838 (w), 2117 (w), 1623 (vs), 1604 (m), 1569 (m), 1510 (s), 1501
(s), 1462 (s), 1426 (m), 1176 (m), 1036 (s), 640 (s) cm–1. MS (EI):
m/z (%) = 392 (100) [M]+·, 377 (12), 361 (19), 354 (43), 345 (21),
307 (18), 289 (42), 279 (23), 263 (18), 252 (17), 239 (25), 226 (23),
217 (15), 189 (20), 171 (33), 149 (54), 138 (18), 121 (32), 97 (15),
83 (17), 71 (26), 57 (37), 43 (23). HRMS (EI): calcd. for C28H24O2
392.1776; found 392. 1776.
134.54 (s), 141.57 (s), 157.91 (s) ppm. IR (CHCl ): ν = 3058 (w),
˜
3
2958 (s), 2944 (vs), 2865 (vs), 2837 [w (sh)], 2170 (m), 1603 (m),
1569 (w), 1500 (m), 1491 (m), 1464 (s), 1444 (w), 1430 (w), 1383
(w), 1366 (w), 1337 (w), 1324 (w), 1291 (w), 1156 (w), 1181 (w),
1073 (w), 1062 (w), 1024 (m), 996 (m), 919 (w), 883 (s), 852 (w),
817 (w), 679 (s) cm–1. MS (EI): m/z (%) = 674 (7) [M]+·, 631 (24),
516 (5), 473 (7), 157 (66), 129 (17), 115 (100), 101 (14), 87 (48), 73
(49), 59 (60), 41 (7). HRMS (EI): calcd. for C45H62OSi2 674.4339;
found 674.4316.
2,15-Dimethoxy-5,6,9,10-tetrahydrohexahelicene (17): A Schlenk
flask was charged with triyne 16 (99 mg, 0.253 mmol) and flushed
with argon. The substrate was dissolved in decane (4 mL) at 90 °C.
Then a solution of triphenylphosphane (27 mg, 0.101 mmol,
40 mol %) in hot decane (1.5 mL) and CpCo(CO)2 (7 µL,
0.53 mmol, 20 mol%) in decane (0.5 mL) were added, and the mix-
ture was stirred at 140 °C for 1 h under concomitant irradiation
with a halogen lamp. The solvent was evaporated in vacuo, and the
residue was chromatographed on silica gel (petroleum ether/diethyl
ether, 95:5) to obtain 17 (55 mg, 56%) as amorphous solid. 1H
NMR (500 MHz, CDCl3): δ = 2.63–2.78 (m, 2 H), 2.81–3.02 (m, 2
2-(3-Butynyl)-1-{[2-(3-butynyl)-5-methoxyphenyl]ethynyl}naphtha-
lene (21): Tetrabutylammonium fluoride (1.07  in THF, 3.20 mL,
3.43 mmol, 2.4 equiv.) was added to silylated triyne 20 (956 mg,
1.42 mmol) in THF (25 mL) under an atmosphere of argon, and the
H), 2.88 (s, 3 H), 3.48 (s, 3 H), 6.12 (d, J = 2.6 Hz, 1 H), 6.44 (dd, mixture was stirred at r.t. for 1 h. The solution was evaporated in
J = 6.8, 2.6 Hz, 1 H), 6.78 (br. d, J = 2.6 Hz, 1 H), 6.83 (dd, J = vacuo to dryness, and the residue was chromatographed on silica gel
8.8, 2.6 Hz, 1 H), 7.05 (br. d, J = 8.1 Hz, 1 H), 7.21 (dd, J = 7.4, (petroleum ether/diethyl ether, 95:5) to obtain 21 (307 mg, 60%) as
1
1.1 Hz, 1 H), 7.27 (dd, J = 7.4, 1.1 Hz, 1 H), 7.34 (br. d, J = 8.0 Hz, an amorphous solid. H NMR (500 MHz, CDCl3): δ = 2.00 (t, J =
1 H), 7.55 (d, J = 8.8 Hz, 1 H), 7.62 (br. d, J = 8.1 Hz, 1 H) ppm.
2.6 Hz, 1 H), 2.02 (t, J = 2.7 Hz, 1 H), 2.64 (dt, J = 7.6, 7.6, 2.6 Hz,
2 H), 2.69 (dt, J = 7.6, 7.6, 2.7 Hz, 2 H), 3.16 (t, J = 7.6 Hz, 2 H),
13C NMR (125.7 MHz, CDCl3): δ = 29.29 (t), 30.46 (t), 30.85 (t),
31.44 (t), 54.53 (q), 54.58 (q), 104.15 (d), 112.17 (d), 114.52 (d), 3.33 (t, J = 7.6 Hz, 2 H), 3.86 (s, 3 H), 6.90 (dd, J = 8.5, 2.7 Hz, 1
117.78 (d), 124.06 (d), 127.27 (d), 127.97 (d), 128.34 (d), 128.35 (d),
128.63 (s), 129.07 (d), 129.79 (s), 130.93 (s), 130.94 (s), 131.28 (s),
133.59 (s), 136.22 (s), 138.11 (s), 139.07 (s), 140.94 (s), 157.42 9s),
H), 7.20 (d, J = 7.7 Hz, 1 H), 7.26 (d, J = 8.5 Hz, 1 H), 7.45 (d, J =
8.5 Hz, 1 H), 7.50 (ddd, J = 8.1, 6.8, 1.3 Hz, 1 H), 7.60 (ddd, J =
8.3, 6.8, 1.3 Hz, 1 H), 7.80 (br. d, J = 8.5 Hz, 1 H), 7.84 (ddt, J =
157.46 (s) ppm. IR (CHCl ): ν = 3050 (w), 2899 (m), 2836 (m), 8.1, 1.3, 0.7, 0.7 Hz, 1 H), 8.43 (ddt, J = 8.3, 1.3, 0.8, 0.8 Hz, 1 H)
˜
3
1624 (vs), 1609 (s), 1598 [m (sh)], 1561 (w), 1571 (m), 1514 (vs),
1498 (vs), 1445 (m), 1411 (m), 1380 (m), 1323 (m), 1307 (m), 1256 (t), 34.59 (t), 55.46 (q), 69.05 (d), 69.12 (s), 83.71 (s), 83.81 (s), 89.39
ppm. 13C NMR (125.7 MHz, CDCl3): δ = 19.82 (t), 20.15 (t), 33.23
(m), 1184 (m), 1175 (s), 1165 [m (sh)], 1050 [w (sh)], 1035 (s), 942
(w), 909 (s), 857 (s), 838 (vs), 825 (s), 811 (w), 636 (w), 516 (w),
558 (w), 431 (vw) cm–1. MS (EI): m/z (%) = 392 (100) [M]+·, 363
(s), 97.17 (s), 115.07 (d), 117.23 (d), 119.36 (s), 123.69 (s), 125.94 (d),
126.08 (d), 127.05 (d), 127.28 (d), 128.17 (d), 128.55 (d), 130.26 (d),
132.03 (s), 133.56 (s), 134.28 (s), 141.33 (s), 158.01 (s) ppm. IR
Eur. J. Org. Chem. 2007, 4244–4250
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
4249

I. G. Stará, I. Starý et al.
FULL PAPER
(CHCl ): ν = 3308 (s), 3059 (w), 2937 (w), 2915 (w), 2864 (w), 2838
= 358 [M]+, 327, 313, 300, 282, 276, 263, 256, 242, 218, 185, 165,
˜
3
(w), 2200 (vw), 2117 (w), 1604 (s), 1569 (w), 1500 (s), 1492 (m), 1466 149, 115, 93, 69, 55. HRMS (FAB): calcd. for C27H18O 358.1358;
(m), 1444 (w), 1433 (w), 1382 (w), 1322 (w), 1293 (w), 1284 (w), 1262
(m), 1235 (m), 1182 (w), 1156 (w), 1116 (w), 1038 (m), 867 (w), 820
(m), 640 (s) cm–1. MS (EI): m/z (%) = 362 (2) [M]+·, 286 (21), 247
(100), 201 (3), 199 (3), 120 (10), 115 (8), 51 (6). HRMS (EI): calcd.
for C27H22O 362.1671; found 362.1678.
found 358.1315.
Supporting Information (see footnote on the first page of this arti-
1
cle): H and 13C NMR spectra for compounds 2, 5, 7–17 and 20–
1
23 and H NMR spectrum for compound 4.
2-Methoxy-5,6,9,10-tetrahydrohexahelicene (22): A Schlenk flask
was charged with triyne 21 (193 mg, 0.532 mmol) and flushed with
argon. The substrate was dissolved in decane (5 mL) at 90 °C. Then
a solution of triphenylphosphane (52 mg, 0.214 mmol, 40 mol%)
in hot decane (3 mL) and CpCo(CO)2 (14 µL, 0.0106 mmol,
20 mol%) were added, and the mixture was stirred at 140 °C for
3 h under concomitant irradiation with a halogen lamp. The sol-
vent was evaporated in vacuo, and the residue was chromato-
graphed on silica gel (petroleum ether/diethyl ether, 99:1 to 95:5) to
obtain 22 (148 mg, 77%) as amorphous solid. 1H NMR (500 MHz,
CDCl3): δ = 2.68–3.02 (m, 8 H), 2.87 (s, 3 H), 6.00 (d, J = 2.6 Hz,
1 H), 6.39 (dd, J = 8.2, 2.6 Hz, 1 H), 6.89 (ddd, J = 8.7, 6.7, 1.4 Hz,
1 H), 7.05 (dd, J = 8.2, 1.1 Hz, 1 H), 7.14 (ddd, J = 8.1, 6.7, 1.1 Hz,
1 H), 7.21 (dd, J = 7.4, 1.1 Hz, 1 H), 7.26 (dd, J = 7.4, 1.2 Hz, 1
H), 7.47 (d, J = 8.2 Hz, 1 H), 7.48 (dq, J = 7.8, 1.0, 1.0, 1.0 Hz, 1
H), 7.65 (ddt, J = 8.1, 1.4, 0.6, 0.6 Hz, 1 H), 7.68 (br. d, J = 8.2 Hz,
1 H) ppm. 13C NMR (125.7 MHz, CDCl3): δ = 29.02 (t), 30.27 (t),
30.59 (t), 31.07 (t), 54.54 (q), 112.34 (d), 114.02 (d), 124.45 (d),
124.93 (d), 125.88 (d), 126.18 (d), 126.26 (d), 126.38 (d), 127.38 (d),
127.46 (d), 127.83 (d), 129.66 (s), 130.32 (s), 130.95 (s), 132.03 (s),
132.97 (s), 134.28 (s), 136.02 (s), 138.12 (s), 140.60 (s), 157.18 (s)
Acknowledgments
Financial support for the work was provided by the FP6 (Pico-
Inside, No. FP6-015847), the Grant Agency of the Czech Republic
(No. 203/06/1792) and Ministry of Education of the Czech Repub-
lic (Centre for Biomolecules and Complex Molecular Systems, the
project LC512; Program Barrande, No. 2005-06-041-1).
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ppm. IR (CHCl ): ν = 2942 (s), 2899 (m), 2837 (m), 1608 (s), 1596
˜
3
(m), 1570 (m), 1509 [m (sh)], 1497 (s), 1419 (w), 1408 (w), 1306
(m), 1183 (m), 1176 (m), 1036 (m), 825 (vs) cm–1. MS (EI): m/z (%) [3] M. T. Reetz, S. Sostmann, R. Goddard, Helixol – A New Li-
= 362 (100) [M]+·, 213 (10), 199 (17), 149 (11), 121 (26), 101 (10),
91 (12), 83 (8), 75 (14), 59 (24), 43 (44). HRMS (EI): calcd. for
C27H22O 362.1671; found 362.1672.
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2-Methoxyhexahelicene (23):
A
solution of 22 (143 mg,
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0.395 mmol) and Ph3CBF4 (391 mg, 1.18 mmol, 3.0 equiv.) in 1,2-
dichloroethane (6 mL) was stirred under an atmosphere of argon
at 80 °C for 3 h. The solvent was removed in vacuo, and the residue
was chromatographed on silica gel (petroleum ether/diethyl ether,
95:5) to obtain 23 (136 mg, 96%)[14] as an amorphous solid. 1H
NMR (500 MHz, CDCl3): δ = 2.90 (s, 3 H), 6.74 (ddd, J = 8.6,
6.9, 1.4 Hz, 1 H), 6.87 (dd, J = 8.7, 2.6 Hz, 1 H), 6.99 (br. d, J =
2.6 Hz, 1 H), 7.27 (ddd, J = 7.9, 6.9, 1.1 Hz, 1 H), 7.66 (ddt, J =
8.6, 1.1, 0.7, 0.7 Hz, 1 H), 7.75 (br. d, J = 8.7 Hz, 1 H), 7.85 (ddd,
J = 7.9, 1.4, 0.6 Hz, 1 H), 7.83 (d, J = 8.4 Hz, 1 H), 7.88 (dt, J =
8.4, 0.6, 0.6 Hz, 1 H), 7.89 (dt, J = 8.5, 0.6, 0.6 Hz, 1 H), 7.96 (d,
J = 8.5 Hz, 1 H), 7.98 (d, J = 8.2 Hz, 2 H), 8.00 (d, J = 8.2 Hz, 1
H), 8.02 (d, J = 8.2 Hz, 1 H) ppm. 13C NMR (125.7 MHz, CDCl3):
δ = 54.23 (q), 107.71 (d), 117.53 (d), 123.86 (d), 124.18 (s), 124.87
(d), 125.94 (d), 126.28 (d), 126.80 (s), 126.86 (d), 126.97 (d), 127.04
(d), 127.26 (d), 127.37 (s), 127.40 (s), 127.44 (d), 127.57 (d), 127.70
(d), 127.82 (d), 129.45 (d), 130.25 (s), 131.05 (s), 131.23 (s), 131.63
ˇ
Fiedler, Collect. Czech. Chem. Commun. 2003, 68, 917; b) F.
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Stará, I. Starý, A. Kollárovicˇ, F. Teplý, S. Vyskocˇil, D. Saman,
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[12] I. G. Stará, I. Starý, A. Kollárovicˇ, F. Teplý, D. Saman, M.
(s), 131.84 (s), 133.07 (s), 157.13 (s) ppm. IR (CHCl ): ν = 3087
˜
3
(w), 3051 (m), 3030 (w), 1621 (m), 1612 (m), 1584 (w), 1522 (w),
1507 (m), 1495 (m), 1479 (m), 1466 (m), 1454 (m), 1449 [w (sh)],
1438 (w), 1430 (m), 1404 (w), 1368 (m), 1292 (w), 1275 (w), 1258
(w), 1231 (s), 1183 (m), 1160 (w), 1153 (w), 1138 (m), 1115 (w),
1091 (w), 1073 [w (sh)], 1050 (w), 1037 (w), 1031 (m), 1002 (w),
870 (m), 849 (vs), 837 (s), 819 (w), 802 (m), 684 (w), 640 (w), 633
(vw), 624 (w), 612 (w), 606 (w), 587 (m), 533 (m), 511 (m), 501 (w),
483 (w), 436 (vw), 429 (vw) cm–1. MS (EI): m/z (%) = 358 (100)
[M]+·, 342 (6), 327 (15), 313 (17), 300 (21), 179 (5), 163 (12), 150
(18), 143 (8), 57 (15), 43 (9). MS (FAB, thioglycerol/glycerol): m/z
ˇ
Tichý, J. Org. Chem. 1998, 68, 4046.
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Received: April 29, 2007
Published Online: July 27, 2007
4250
www.eurjoc.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2007, 4244–4250