Highly modular assembly of cationic helical scaffolds: rapid synthesis of diverse helquats via differential quaternization

Article abstract of DOI:10.1016/j.tet.2010.03.007

A protocol for rapid and highly modular assembly of a diverse set of helquats is described. From a common bis-isoquinoline precursor, two successive distinct pyridine-type nitrogen quaternizations followed by rhodium-catalyzed [2+2+2] cycloaddition afford non-symmetric [7]helquats. This route allows for straightforward molecular editing of cationic helical skeletons as exemplified by the synthesis of 15 different [5]-, [6]-, and [7]helquats.

Full text of DOI:10.1016/j.tet.2010.03.007

Tetrahedron 66 (2010) 3537–3552
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Highly modular assembly of cationic helical scaffolds: rapid synthesis of diverse
helquats via differential quaternization
a
,
,
y
a
,
y
a
b
Lukas Severa y, Louis Adriaenssens a , Jan Vavra , David Saman , Ivana Cısarova ,
ˇ
´ ˇ
´
´
ˇ
´
a
a,
*
´
Pavel Fiedler , Filip Teply
a Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, v.v.i., Flemingovo n. 2, Prague 166 10, Czech Republic
b Department of Inorganic Chemistry, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history:
A protocol for rapid and highly modular assembly of a diverse set of helquats is described. From
a common bis-isoquinoline precursor, two successive distinct pyridine-type nitrogen quaternizations
followed by rhodium-catalyzed [2þ2þ2] cycloaddition afford non-symmetric [7]helquats. This route
allows for straightforward molecular editing of cationic helical skeletons as exemplified by the synthesis
of 15 different [5]-, [6]-, and [7]helquats.
Received 14 September 2009
Received in revised form 8 February 2010
Accepted 1 March 2010
Available online 6 March 2010
Ó 2010 Elsevier Ltd. All rights reserved.
Keywords:
Helquat
Helicene-viologen hybrid
Helical dicatione
Extended diquat
N-heteroaromatic cation
[2+2+2] Cycloaddition
Triyne cycloisomerization
Diynes and triynes
Wilkinson’s catalyst
Rhodium
Step economy
Selectivity
Successive N-quaternizations
1. Introduction
The family of N-heteroaromatic cations1 features important fluo-
rescent dyes for bio-imaging2 and non-linear optics,2c,3 sensitizers for
photography,4 a variety of biologically active species,5 molecular
machine prototypes,6 ionic liquids,7 and organocatalysts.8
Inspired by the wealth of applications of this class of compounds,
we recently introduced helquats,9 helical dications that represent
a missing structural link between helicenes10,11 and viologens.12
Specifically, basic [7]helquat13 is a structural hybrid between [7]hel-
icene and a well known herbicide diquat12d,k (Scheme 1). Synthesis of
[7]helquat 1 starts with bisquaternization of bis-isoquinoline pre-
cursor2 withan excessof3-butynyltriflatefollowedby thekey metal-
catalyzed [2þ2þ2] cycloisomerization9a,14 of the resulting triyne 3
(Scheme 2). Due to the wide variety of alkynyltriflates that can be
Scheme 1. Structural relation of [7]helquat to [7]helicene and herbicide diquat.
2TfO-
2TfO-
N+
N+
N+
N
N
TfO
2.7 eq
[M]
CCl4/CH2Cl2
N+
41 %
2
1
3
* Corresponding author. E-mail address: teply@uochb.cas.cz.
These three authors have contributed equally to this work.
Scheme 2. Synthesis of basic [7]helquat via one-pot bis-quaternization.9a
y
0040-4020/$ – see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.03.007

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L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
2TfO-
used, the route allows the synthesis of many symmetric helquats for
each bis-pyridine type precursor.9a
N+
N+
N+
N+
2TfO-
82%
We were intrigued by the possibilityof sequentiallyattaching two
different pendent alkyne moieties, thus dramatically increasing the
versatility of the route. We believed we could stop the reaction at the
monocation stage (Scheme 3) by using 1 equiv of quaternization
agent in a low polarity solvent. Such scenario should lead to selective
precipitation of monocationic product. In case the precipitation
should not take place, tendency toward mono-quaternizationwill be
governed by the likely non-equal reactivity of the pyridine-type ni-
trogen centers before and after the first quaternization step. Spe-
cifically, after the first quaternization, the nucleophilicity of the
remaining free pyridine-type nitrogen atomwill be decreased due to
its conjugation with the newly formed electron poor pyridinium-
type moiety, which will suppress formation of bisquaternization
product. A second quaternization with a different triflate would
provide non-symmetric triynes, and consequently more structurally
complex helquats. This would considerably expand the scope of the
synthesis of helquats allowing adjustments to the shape and sub-
stitution of the helix in a most straightforward manner.
D
14
7
81%
TfO-
2TfO-
N+
N
N+
N+
N+
N+
69%
2TfO-
E
61%
n-C10H21
n-C10H21
15
8
B
62%
4
2TfO-
2TfO-
N+
N+
N+
N+
75%
A
89%
F
72%
9
16
2TfO-
N+
N+
N+
N
N
96%
N+
17
2TfO-
10
B
2
TfO-
2TfO-
54%
N+
N+
90%
N+
N+
N+
Ph
C
C
N
18
95%
58%
11
5
2TfO-
2TfO-
N+
N+
N+
N+
86%
A
84%
TfO-
19
N+
N
12
2TfO-
2TfO-
D
N+
N+
N+
N+
74%
81%
6
20
13
TfO
TfO
TfO
D
TfO
TfO
A
B
Scheme 3. Rationale for two-step differential quaternization leading to non-symmetric
helquats.
E
F
n-C10H21
TfO
C
2. Results and discussion
Scheme 4. Diversification of substrate 2 into seven selected non-symmetric [7]hel-
quats. Reagents and conditions: first quaternization: triflate (1.1 equiv), toluene, 25 ꢀC,
24–25 h; second quaternization: triflate (4–4.6 equiv), CH2Cl2, 25–35 ꢀC, 46–95 h;
[2þ2þ2] cycloaddition: [Rh(PPh3)3Cl] (10–14 mol %), DMF, 110–130 ꢀC, 1-2 h.16
We found that clean formation of monocationic product 4 takes
place employing just 1.1 equiv of 3-butynyltriflate in toluene as
a solvent (Scheme 4, 2/4). Gratifyingly, the formation of the
dication 3 is completely blocked under these conditions and only
clean monocation 4 spontaneously precipitates from the reaction
mixture in high yield. Analogous monocations 5 and 6 can be
prepared equally well using this protocol. With these three mon-
ocations in hand we set out to prepare a series of non-symmetric
dications 7–13 (Scheme 4). The second N-quaternization proceeds
smoothly in CH2Cl2 with an excess of the triflate reagent and the
non-symmetric dications 7–13 are isolated typically in good yields
and purities. The final intramolecular [2þ2þ2] cycloadditions of
the triynes 7–13 are facile and open access to a series of non-
symmetric [7]helquats 14–20.15
The diversification made possible by the presented route de-
serves special attention. Thus, by combining one symmetric bis-
isoquinoline precursor 2 and six distinct triflates (A–F, see inset in
Scheme 4) as many as 15 non-symmetric helquats can be targeted17
from which seven selected examples are shown in Scheme 4.
To extend this differential quaternization protocol, we decided
to explore substrates containing two non-equivalent pyridine-type
nitrogen atoms. Notably, if regioselective mono-quaternization of
the non-symmetric precursor 21 (Scheme 5), having two different
nitrogen sites, is feasible, then the differential quaternization using
the same six triflates mentioned above (A–F) would now open
pyridine-nitrogen site
quaternized preferentially
TfO-
TfO
2TfO-
N+
N
N+
N+
N
N
TfO
H
21
22
electronics and
steric hindrance
impede
TfO-
2TfO-
N+
N
N+
N+
nucleophilicity
TfO
TfO
23
Scheme 5. Differential quaternization of a substrate with non-equivalent nitrogen sites.
access to a set of 30 distinct [5]helquats.18 To demonstrate the
preparative power of this strategy we set out to synthesize all six
possible non-symmetric [5]helquats starting from 21 and three
selected triflates (A, C, D, Scheme 6).

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3539
2TfO-
N+
2TfO-
N+
N+
79%
D
N+
51%
TfO-
N+
N
25
31
2TfO-
N+
2TfO-
N+
N+
C
66%
53%
N+
22
26
32
2TfO-
N+
2TfO-
75%
N+
N+
A
76%
A
N+
56%
TfO-
27
33
N
N+
Figure 1. X-ray single crystal structure of compounds 18, 29, 35, and 43. Triflate
D
counterions are omitted for clarity.
2TfO-
2TfO-
N+
67%
N+
N+
N
N
C
65%
51%
N+
21
23
28
34
2TfO-
2TfO-
61%
C
N+
N+
N+
80%
A
46%
TfO-
N+
N+
N
29
35
2TfO-
2TfO-
D
N+
N+
N+
N+
Scheme 7. Diversification of precursor 37 into isomeric [6]helquats 40 and 4315 by
changing the quaternization order. Reagents and conditions: (a) A (1.1 equiv), toluene,
ꢁ10 ꢀC, 17 h, 49%; (b) C (1.1 equiv), toluene, ꢁ10 ꢀC, 17 h, 58%; (c) C (4 equiv), CH2Cl2,
25 ꢀC, 36 h, 82%; (d) A (4 equiv), CH2Cl2, 25 ꢀC, 36 h, 71%; (e) [Rh(PPh3)3Cl] (6 mol %),
DMF, 100 ꢀC, 1 h, 84%; (f) [Rh(PPh3)3Cl] (8 mol %), DMF, 100 ꢀC, 1 h, 99%.16
55%
69%
24
TfO
TfO
A
D
C
30
36
TfO
(ratio 6:1), sufficiently pure material21 is obtained by means of
a single recrystallization. The second quaternization and the sub-
sequent cyclization both proceeded without difficulty to give the
desired helquat 40. Correspondingly, the isomeric helquat 43 was
produced by simply switching the order of quaternization steps
(see Fig. 1 for X-ray of 43).15
Scheme 6. A single unsymmetric precursor 21 and three alkynyltriflates A, D, C lead to
six distinct [5]helquats13 in total. Reagents and conditions: first quaternization: triflate
(1.1 equiv), toluene, 25 ꢀC, 15 h; second quaternization: triflate (2–2.2 equiv), CH2Cl2,
50 ꢀC, 48 h; [2þ2þ2] cycloaddition: [Rh(PPh3)3Cl] (10–14 mol %), DMF, 90 ꢀC, 30 min.16
The nitrogen atom in the quinoline moiety of 21 is expected to
be not only less basic19 but also less accessible due to the presence
of the hydrogen atom in the peri-position20 (Scheme 5). Taking
advantage of this, three distinct monocations 22, 23, and 24 were
prepared via regioselective mono-quaternization of 21 at the pyr-
idine moiety. Subsequently, the monocations 22–24 were di-
versified into six distinct dications 25–30 (two dications from each
monocation).15 The six triynes prepared in this manner smoothly
underwent the key intramolecular [2þ2þ2] cycloaddition giving
the corresponding helquats 31–36. See Figure 1 for X-ray of triyne
29 and helquat 35.15
Next we turned to a more challenging substrate 37, where the
annulated benzene ring imparts no significant steric bias to the two
reactive nitrogen sites (Scheme 7). In this respect, substrate 37 is
markedly different from substrate 21 in that its two nucleophilic
sites differ only electronically (cf. 37/38 and 21/22).
3. Conclusion
In summary, by taking advantage of two successive distinct
pyridine-type nitrogen quaternizations we demonstrate that a wide
range of dicationic helical scaffolds can be rapidly accessed. The use
of pyridine-type nitrogen as a functionalization handle22 makes the
route exclusively skeleton-building and therefore markedly step
economic.23 This allows the preparation of 15 helquats in only 38
steps in total24 starting from three precursors (2, 21, and 37) and
a set of six triflates A–F. Noteworthy is also the outstanding mod-
ularity inherent to this approach. The same three substrates and six
triflates would give rise to a possible 75 non-symmetric helquats in
total.25 All in all, the outlined synthetic protocol considerably ex-
pands the utility of the synthesis of helquats and allows for
straightforward molecular editing of cationic scaffolds. This will
enable the tailoring of cationic species toward the targeted mole-
cular properties in the pursuit of specific applications.
Fortunately, under carefully controlled conditions preferential
mono-quaternization of the isoquinoline moiety can be achieved
(37/38). Although the other regioisomer of 38 is also formed

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L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
4. Experimental
samples due to the formation of strongly colored charge-transfer
species (discussion in Ref. 12d, page 33). Such species are very
probably the cause of the color of some compound samples in this
report (e.g., in compounds 31–36). However, we note that only
trace amounts of these impurities can be present as suggested both
by elemental analyses and NMR spectra (see Supplementary data
section for NMR scans). Consequently, according to the elemental
analyses and NMR spectra, we regard all the compounds reported
herein to be of sufficient purity for all practical purposes and de-
mands of organic synthesis, e.g., as starting materials, reagents, or
catalysts. Nevertheless, we note that samples described as ‘brown’
in this report, most probably will not be suitable for ‘photonic’ re-
search (e.g., fluorescence studies) unless higher purity will be
achieved by additional purification. In this context, we also note
that attempted decolorizing by using charcoal does not appear
effective in cases tested.
4.1. General information
Materials, see the Supplementary data section for details. Liq-
uids and solutions were added via needle and syringe unless oth-
erwise stated. Melting points were determined on a Wagner &
Munz PolyTherm A micro melting point apparatus and are un-
corrected. Thin-layer chromatography (TLC) analysis was per-
formed on silica gel plates (Silica gel 60 F254-coated aluminum
sheets, Merck, cat. no. 1.05554.0001) and visualized by UV (UV
lamp 254/365 nm, SpectrolineÒ Model ENFd240C/FE) and/or
chemical staining with KMnO4 [KMnO4 (1% aq), Na2CO3 (2% aq)].
Thin-layer chromatography (TLC) analysis of organic cation salts
was achieved using Stoddart’s magic mixture26 (MeOH/
NH4Claq(2 M)/MeNO2 70:20:10) as eluent on silica gel plates. Flash
chromatography was performed on silica gel 60 (Fluka, cat. no.
60741) with the indicated eluent. Distillations of triflates were
carried out bulb to bulb in a Bu¨chi B-585 Kugelrohr Apparatus.
Reactions using microwave irradiation were performed in a CEM
DISCOVERY microwave system, using CEM ‘snap on’ caps. Sonica-
tion was conducted with a BANDELIN SONOREX sonicator. NMR
spectra were measured on a Bruker Avance 600 (600 MHz for 1H,
151 MHz for 13C), or Bruker Avance 400 (400 MHz for 1H,
4.2. Synthesis of triflates A–F, general
Recently Quagliotto et al. published paper detailing a facile
method for producing triflates.27 We have found this procedure
particularly convenient. Once prepared, the triflates can be stored
for months in the freezer, showing no signs of significant de-
composition (as seen by 1H NMR and coloration of the material).
The triflates are generally obtained as brown liquids, and can be
distilled to give colorless liquids. Bulb to bulb distillation using
a Kugelrohr apparatus proved to be especially practical. With or
without distillation the triflates gave good results in the trans-
formations described in this paper. It should be noted that the
densities of the triflates varied slightly between different runs.
Procedure: A solution of the desired alcohol (1 equiv) and dry
pyridine (1 equiv) in dry DCM is added dropwise via syringe to
a stirring solution of trifluoromethanesulfonic anhydride (1 equiv)
in dry DCM at 0 ꢀC under Ar. Upon addition a white precipitate of
pyridinium triflate forms. The reaction mixture stirs at 0 ꢀC for
0.5 h, and is then diluted with water. The organic layer is separated
and washed with water (1ꢂ), dried over Na2SO4, filtered and con-
centrated in vacuo (300 mbar at 25 ꢀC) to give a light rose colored
liquid.
100.6 MHz for 13C) NMR spectrometer in CDCl3
(
dC¼77.00 ppm)
with TMS as internal standard (dH¼0 ppm), acetone referenced to
the CHD2COCD3 peak (dH¼2.09 ppm), (CD3)2CO (dC¼29.80 ppm).
Chemical shifts are given in d-scale as parts per million (ppm);
coupling constants (J) are given in Hertz. Where indicated, the
signal assignments in the NMR spectra are unambiguous; the
numbering scheme is arbitrary and is shown in the inserts. Where
assigned, all 1H and 13C resonance assignments are based on
analysis of H,H-COSY; H,H-ROESY; H,C-HSQC and H,C-HMBC spec-
tra. IR spectra were recorded on a Bruker EQUINOX55 (IFS55)
spectrometer in CHCl3, or CCl4 (cuvette width 0.1 mm), or as KBr
pellets. Abbreviation for intensities of IR bands are as follows: s for
strong, vs for very strong, m for medium, w for weak. Mass spectral
data were obtained at the Mass Spectrometry Facility operated by
the Institute of Organic Chemistry and Biochemistry, Academy of
Sciences of the Czech Republic. EIMS spectra were measured at an
electron energy of 70 eV; m/z values are given along with their
relative intensities (%). FABMS spectra were measured using a
thioglycerol–glycerol 3:1 matrix; m/z values are given. In the case of
APCI MS spectra measurements, the samples were dissolved in
acetone and directly infused into an APCI source (probe tempera-
ture 300 ꢀC, source block temperature 120 ꢀC, corona current
4.2.1. But-3-ynyl trifluoromethanesulfonate (A). Following the gen-
eral procedure for triflate formation, a solution of 3-butyn-1-ol
(1.38 mL, 18.3 mmol, 1 equiv), and pyridine (1.48 mL, 18.3 mmol,
1 equiv) in DCM (7 mL), and a solution of trifluoromethanesulfonic
anhydride (3.0 mL, 18.3 mmol, 1 equiv) in DCM (10 mL) gave but-
3-ynyl trifluoromethanesulfonate (A) as a colorless liquid after
distillation in 52% yield (1.921 g, 9.5 mmol). The spectroscopic
characterization data is in agreement with the literature.27
3.0 mA, cone voltage 25 V). ESI mass spectra were recorded using
a Thermo Scientific LCQ Fleet mass spectrometer equipped with an
electrospray ion source and controlled by Xcalibur software. The
mobile phase consisted of methanol/water (9:1), flow rate of
d¼1.33. Bp 55 ꢀC at 2 mbar. 1H NMR (400 MHz, CDCl3):
¼2.11 (t,
d
J¼2.7 Hz, 1H); 2.73 (td, J¼6.7, 2.7 Hz, 2H); 4.57 (t, J¼6.7 Hz, 2H). 13C
200
ml/min. The sample was dissolved, diluted with the mobile
NMR (100 MHz, CDCl3):
d
¼19.89; 71.77; 73.50; 76.86; 118.61 (q,
phase and injected using a 5
m
l loop. Spray voltage, capillary volt-
J¼319.6 Hz). Elem. Anal. Calcd for C5H5F3O3S: C, 29.71; H, 2.49; S,
age, tube lens voltage and capillary temperature were 5.5 kV, 5 V,
80 V and 275 ꢀC, respectively. HRMS spectra were obtained with
the EI or APCI instruments.
15.86. Found: C, 29.65; H, 2.45; S, 15.67.
4.2.2. 4-Phenylbut-3-ynyl trifluoromethanesulfonate (B). Following
Water content in organic cations: often the samples of the or-
ganic cations contained varying amounts of water (usually 0.5–2
molecules of water per monocation or dication) as evidenced by
respective NMR as well as elemental analyses. Water content in the
individual samples can vary slightly between different preparations
of the compounds.
Coloration of some compound samples (e.g., brown compound
samples 31–36 in Scheme 6): From viologen chemistry it is known
that trace amounts of pyridine-type starting materials sometimes
remain in products after N-quaternization reaction steps. They can
be difficult to remove and are typically cause of color in viologen
the general procedure for triflate formation, a solution of 4-phenyl-
but-3-yn-1-ol28 (66.0 mg, 0.45 mmol, 1 equiv) and pyridine (36.0
m
L,
0.45 mmol, 1 equiv) in DCM (2 mL) and a solution of trifluoro-
methanesulfonic anhydride (77 L, 0.45 mmol, 1 equiv) in DCM
m
(2 mL) gave pure 4-phenylbut-3-ynyl trifluoromethanesulfonate (B)
as a brown liquid in 93% yield (117 mg, 0.42 mmol). The spectroscopic
characterization data is in agreement with the literature.29
d¼1.34. 1H NMR (400 MHz, CDCl3):
¼2.97 (t, J¼6.8 Hz, 2H);
d
4.66 (t, J¼6.8 Hz, 2H); 7.27–7.36 (m, 2H); 7.38–7.45 (m, 3H). 13C
NMR (100 MHz, CDCl3):
J¼319.8 Hz); 122.56; 128.31; 128.41; 131.68.
d
¼20.85; 73.84; 82.04; 83.69; 118.64 (q,

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3541
4.2.3. Pent-4-ynyl trifluoromethanesulfonate (C)30. Following the
4.4. Workup procedure I (4, 5, 6)
general procedure for triflate formation, a solution of 4-pentyn-1-ol
(1.0 mL, 10.7 mmol, 1 equiv) and pyridine (0.84 mL, 10.4 mmol,
0.97 equiv) in DCM (6 mL) and a solution of trifluoromethanesulfonic
anhydride (1.85 mL, 11.3 mmol, 1.06 equiv) in DCM (6 mL) gave pure
pent-4-ynyl trifluoromethanesulfonate (C) as a colorless liquid after
distillation in 84% yield (1.950 g, 9.03 mmol).
The supernatant solution was separated from the fine powder
via centrifuge and then removed via decantation. Reagent grade
toluene was added to the powder, now contained in a centrifuge
tube, and the suspension was sonicated to ensure good mixing of
the solid and supernatant solution. The supernatant solution was
once again separated from the solid via centrifugation and de-
cantation. The toluene washing procedure was repeated. The
product was transferred to a vial and dried under vacuum (2 mbar)
to give pure organic monocation salt.
d¼1.42. Bp 55 ꢀC at 2 mbar. 1H NMR (400 MHz, CDCl3):
¼1.99–
d
2.09 (m, 2H); 2.03 (t, J¼2.7 Hz, 1H); 2.39 (td, J¼6.8, 2.7 Hz, 2H); 4.68
(t, J¼6.1 Hz, 2H). 13C NMR (100 MHz, CDCl3):
¼14.49; 28.01; 70.22;
d
75.43; 81.13; 118.64 (q, J¼319.6 Hz). Elem. Anal. Calcd for
C6H7F3O3S: C, 33.34; H, 3.26; S, 14.83. Found: C, 33.15; H, 3.26; S,
14.68.
4.5. Workup procedure II (22, 23, 24)
4.2.4. Pent-3-ynyl trifluoromethanesulfonate (D). Following the
general procedure for triflate formation, a solution of pent-3-yn-1-
ol (0.28 mL, 3.05 mmol, 1 equiv) and pyridine (0.25 mL, 3.05 mmol,
1 equiv) in DCM (1.2 mL) and a solution of trifluoromethanesulfonic
anhydride (0.5 mL, 3.05 mmol, 1 equiv) in DCM (1.7 mL) gave pure
pent-3-ynyl trifluoromethanesulfonate (D) as a colorless liquid af-
ter distillation in 53% yield (0.350 g, 1.62 mmol). The spectroscopic
characterization data is in agreement with the literature.31
The precipitate was isolated via filtration and the filter cake was
washed with cold diethyl ether. Diethyl ether/tetrahydrofuran 1:1
(8 mL) was added to the powder and this mixture, contained in
a RBF, was immersed in an ultrasonic bath and sonicated for 1 min.
The supernatant solution was separated from the solid via centri-
fugation and decantation. The diethyl ether/tetrahydrofuran
washing procedure was repeated (2ꢂ). The fine solid was isolated
via filtration, transferred to a vial and dried under vacuum (2 mbar)
to give pure organic monocation salt.
d¼1.28. Bp 65 ꢀC at 2 mbar. 1H NMR (400 MHz, CDCl3):
¼1.78 (t,
d
J¼2.5, 3H); 2.67 (tq, J¼6.9, 2.5 Hz, 2H); 4.53 (t, J¼6.9 Hz, 2H). 13C
NMR (100 MHz, CDCl3):
d
¼3.28; 20.19; 71.67; 74.41; 79.41; 118.62
4.6. Workup procedure III (38, 41)
(q, J¼319.6 Hz). Elem. Anal. Calcd for C6H7F3O3S: C, 33.39; H, 3.26; S,
14.83. Found: C, 32.97; H, 3.27; S, 14.67.
The precipitate was isolated via filtration and the filter cake was
washed with toluene, followed by hexane. The crude product was
dissolved in a 1:1 mixture of toluene and 2-propanol aided bygentle
warming with a heat gun (maximum temperature 50 ꢀC). The so-
lution was closed with a glass stopper and cooled to ꢁ20 ꢀC. After
two days the desired product had crystallized and was isolated by
filtration. The crystals were washed first with a cold 2:1 mixture of
toluene and 2-propanol, and then with hexane. The crystals were
collected and dried to give the organic monocation salt.
4.2.5. Tetradec-3-ynyl trifluoromethanesulfonate (E). Following the
general procedure for triflate formation, a solution of tetradec-3-
yn-1-ol (143.4 mg, 0.68 mmol, 1 equiv) and pyridine (55
0.68 mmol, 1 equiv) in DCM (2 mL) and solution of tri-
fluoromethanesulfonic anhydride (117 L, 0.70 mmol,1.03 equiv) in
mL,
a
m
DCM (2 mL) gave tetradec-3-ynyl trifluoromethanesulfonate (E) as
a yellow liquid in 96% yield (0.2254 g, 0.66 mmol).
d¼1.09. 1H NMR (400 MHz, CDCl3):
¼0.88 (t, J¼6.8 Hz, 3H); 1.17–
d
1.40 (m, 14H); 1.42–1.53 (m, 2H); 2.14 (tt, J¼7.1, 2.3 Hz, 2H); 2.69 (tt,
4.6.1. 2-(But-3-ynyl)-1-(isoquinolin-1-ylethynyl)isoquinolinium tri-
fluoromethanesulfonate (4). Following the general procedure for
organic monocation formation with a reaction temperature of
25 ꢀC, and general workup procedure I, a solution of but-3-ynyl
J¼6.9, 2.3 Hz, 2H); 4.53 (t, J¼6.9 Hz, 2H).13C NMR (151 MHz, acetone-
d6):
d
¼14.31; 18.94; 20.51; 23.28; 29.42; 29.45; 29.83; 30.01; 30.22;
30.25; 32.57; 74.54; 77.28; 83.67; 118.92 (q, J¼319.6 Hz).
trifluoromethanesulfonate (A) (110 ml, 0.8017 mmol, 1.1 equiv) in
4.2.6. Hex-5-ynyl trifluoromethanesulfonate (F). Following the gen-
eral procedure for triflate formation, a solution of hex-5-yn-1-ol
(0.50 mL, 4.61 mmol, 1 equiv) and pyridine (0.37 mL, 4.57 mmol,
0.99 equiv) in DCM (5 mL) and a solution of trifluoromethanesulfonic
anhydride (0.78 mL, 4.70 mmol,1.02 equiv) in DCM (5 mL) gave hex-
5-ynyl trifluoromethanesulfonate (F) as a brown liquid in 79% yield
(0.8348 g, 3.63 mmol). The spectroscopic characterization data is in
agreement with the literature.32
toluene (4 mL) and a solution of 1,2-di(isoquinolin-1-yl)ethyne
(2)33 (204.3 mg, 0.7288 mmol, 1 equiv) in toluene (16 mL) gave
pure organic monocation salt 4 as a yellow powder in 89% yield
(315.9 mg, 0.6547 mmol).
Mp 145–147 ꢀC. 1H NMR (400 MHz, acetone-d6):
d¼2.81 (t,
J¼2.7 Hz, 1H); 3.46 (td, J¼6.8, 2.7 Hz, 2H); 5.62 (t, J¼6.8 Hz, 2H);
7.96–8.05 (m, 2H); 8.23 (dd, J¼5.6, 1.0 Hz, 1H); 8.24–8.28 (m, 1H);
8.38 (ddd, J¼8.4, 7.0, 1.2 Hz, 1H); 8.47 (ddd, J¼8.3, 7.0, 1.2 Hz, 1H);
8.59 (dt, J¼8.2, 1.0 Hz, 1H); 8.70 (m, 1H); 8.86 (m, 1H); 8.88 (d,
J¼5.6 Hz,1H); 9.10 (ddt, J¼8.5, 1.1, 0.9 Hz,1H); 9.19 (d, J¼6.9 Hz, 1H).
d¼1.33. 1H NMR (400 MHz, CDCl3):
¼1.62–1.72 (m, 2H); 1.93–
d
2.02 (m, 2H); 1.99 (t, J¼2.7 Hz, 1H); 2.28 (td, J¼6.8, 2.7 Hz, 2H); 4.58
(t, J¼6.3 Hz, 2H). 13C NMR (100 MHz, CDCl3):
69.43; 76.90; 82.83; 118.66 (q, J¼319.6 Hz).
d
¼17.71; 23.91; 28.17;
13C NMR (151 MHz, acetone-d6):
80.90; 109.72; 124.77; 126.50; 127.13; 128.63; 129.23; 130.01;
d
¼20.81; 60.05; 74.75; 79.28;
130.64; 130.67; 130.69; 132.49; 133.96; 136.88; 137.85; 138.23;
~
138.55; 141.10; 141.32; 144.76. IR (KBr):
n
(cmꢁ1) 1031s, 1160m,
4.3. Synthesis of organic monocations
1224m, 1263vs, 1278vs, 3085w. MS (ESI) m/z: 333 [(MꢁOTf)þ]
(100). HRMS (ESI) m/z: [(MꢁOTf)þ] (C24H17N2) calcd: 333.1386,
found: 333.1386. Elem. Anal. Calcd for C25H17F3N2O3S: C, 62.23; H,
3.55; N, 5.81. Found: C, 62.05; H, 3.71; N, 5.48.
Organic monocations were synthesized by a general procedure,
which was followed by one of three workup procedures. The de-
sired alkynyltriflate (A–F) (1.1 equiv) was added dropwise, either as
a solution in toluene or neat, to a stirred solution of Sonogashira
coupling product (2, 21, 37) (1 equiv) in dry toluene at ꢁ10 ꢀC or
25 ꢀC under Ar. The flask was protected from light with Al-foil and
the reaction stirred at the previously noted temperature for 25 h
during which time the product precipitated out of solution as a fine
suspension.
4.6.2. 1-(Isoquinolin-1-ylethynyl)-2-(4-phenylbut-3-ynyl)isoquinoli-
nium trifluoromethanesulfonate (5). Following the general pro-
cedure for organic monocation formation with
temperature of 25 ꢀC, and general workup procedure I, a solution
of 4-phenylbut-3-ynyl trifluoromethanesulfonate (B) (71 l,
0.3396 mmol, 1.1 equiv) in toluene (4 mL) and a solution of 1,2-
a reaction
m

3542
L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
di(isoquinolin-1-yl)ethyne (2)33 (86.5 mg, 0.3086 mmol, 1 equiv) in
toluene (7 mL) gave pure organic monocation salt 5 as a yellow
powder in 90% yield (156.4 mg, 0.2800 mmol).
4.6.5. 1-(Pent-3-ynyl)-2-(quinolin-2-ylethynyl)pyridinium trifluorome-
thanesulfonate (23). Following the general procedure for organic
monocation formation with a reaction temperature of 25 ꢀC, and
general workup procedure II, neat pent-3-ynyl trifluoro-
Mp 186–188 ꢀC. 1H NMR (400 MHz, acetone-d6):
d¼3.69 (t,
J¼6.6 Hz, 2H); 5.72 (t, J¼6.6 Hz, 2H); 7.25–7.45 (m, 5H); 7.92 (ddd,
J¼8.2, 6.9, 1.3, 1H); 8.00 (ddd, J¼8.3, 6.9, 1.3, 1H); 8.22 (dd, J¼5.6,
0.9 Hz, 1H); 8.23–8.26 (m, 1H); 8.38 (ddd, J¼8.4, 7.0, 1.2 Hz, 1H);
8.47 (ddd, J¼8.3, 6.9, 1.2 Hz, 1H); 8.59 (dt, J¼8.5, 0.9 Hz, 1H); 8.69
(dq, J¼8.4,1.0 Hz,1H); 8.87 (d, J¼5.7 Hz,1H); 8.90 (dd, J¼6.8, 0.7 Hz,
1H); 9.12 (dq, J¼8.5, 0.9 Hz, 1H); 9.27 (d, J¼6.9 Hz, 1H). 13C NMR
methanesulfonate (D) (150 ml, 215.0 mg, 0.99 mmol, 1.1 equiv) and
a solution of 2-(pyridin-2-ylethynyl)quinoline (21)33 (208.2 mg,
0.90 mmol, 1 equiv) in toluene (6 mL) gave organic monocation salt
23 as a light gray powder in 67% yield (273.0 mg, 0.60 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.73. Mp 119–121 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d
¼1.76 (t, J¼2.5 Hz, 3H), 3.21 (tq,
(151 MHz, acetone-d6):
123.32; 124.75; 126.46; 127.14; 128.63; 129.286; 129.287; 129.34;
130.05; 130.62; 130.64; 130.66; 132.10; 132.45; 134.01; 136.88;
d
¼21.97; 60.30; 81.01; 84.94; 85.48; 109.67;
J¼6.5, 2.5 Hz, 2H), 5.30 (t, J¼6.5 Hz, 2H), 7.81 (ddd, J¼8.1, 6.9, 1.2 Hz,
1H), 7.96 (ddd, J¼8.5, 6.9, 1.2 Hz, 1H), 8.05 (d, J¼8.4 Hz, 1H), 8.14
(ddt, J¼8.1, 1.5, 0.7 Hz, 1H), 8.18 (ddd, J¼8.5, 1.2, 0.8 Hz, 1H), 8.42
(ddd, J¼7.7, 6.2, 1.5 Hz, 1H), 8.62 (dd, J¼8.4, 1.2 Hz, 1H), 8.71 (ddd,
J¼8.0, 1.5, 0.6, 1H), 8.91 (td, J¼7.9, 1.5 Hz, 1H), 9.40 (ddd, J¼6.2, 1.5,
ꢁ1
~
137.82; 138.25; 138.57; 141.19; 141.34; 144.76. IR (KBr):
n
(cm
)
1029s, 1162s, 1258vs, 1273vs, 3057w. MS (ESI) m/z: 464 (30), 409
[(MꢁOTf)þ] (100), 279 (15). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C30H21N2) calcd: 409.1699, found: 409.1706.
0.6 Hz, 1H). 13C NMR (151 MHz, acetone-d6):
d¼3.09, 21.06, 60.20,
73.83, 78.29, 81.78, 104.77, 125.55, 128.65, 129.00, 129.04, 129.67,
130.21, 131.79, 133.98, 137.55, 138.02, 141.03, 146.94, 148.28, 149.22.
(cmꢁ1) 1030vs; 1167s; 1272s; 1617m; 3082w. MS (ESI)
~
4.6.3. 1-(Isoquinolin-1-ylethynyl)-2-(pent-4-ynyl)isoquinolinium
trifluoromethanesulfonate (6). Following the general procedure for
organic monocation formation with a reaction temperature of
25 ꢀC, and general workup procedure I, a solution of pent-4-ynyl
IR (KBr):
n
m/z: 297 [(MꢁOTf)þ] (100). HRMS (ESI) m/z: [(MꢁOTf)þ] (C21H17N2)
calcd: 297.1386, found: 297.1387. Elem. Anal. Calcd for
C22H17F3N2O3S$(H2O)0.5 C, 58.02; H, 3.98; F, 12.51; N, 6.15; S, 7.04.
Found: C, 58.30; H, 3.78; F, 12.19; N, 5.89; S, 7.33.
trifluoromethanesulfonate (C) (80 ml, 0.5121 mmol, 1.1 equiv) in
toluene (6 mL) and a solution of 1,2-di(isoquinolin-1-yl)ethyne
(2)33 (130.5 mg, 0.4655 mmol, 1 equiv) in toluene (10 mL) gave
pure organic monocation salt 6 as a yellow powder in 95% yield
(219.8 mg, 0.4427 mmol).
4.6.6. 1-(Pent-4-ynyl)-2-(quinolin-2-ylethynyl)pyridinium trifluorome-
thanesulfonate (24). Following the general procedure for organic
monocation formation with a reaction temperature of 25 ꢀC, and
Mp 152–154 ꢀC. 1H NMR (600 MHz, acetone-d6):
d¼2.39 (t,
general
workup
procedure II,
neat
pent-4-ynyl
tri-
J¼2.6 Hz, 1H); 2.63–2.71 (m, 4H); 5.52 (t, J¼6.5 Hz, 2H); 7.99 (ddd,
J¼8.2, 6.9, 1.4 Hz, 1H); 8.02 (ddd, J¼8.5, 6.9, 1.5 Hz, 1H); 8.22 (dd,
J¼5.6, 1.2 Hz, 1H); 8.25 (m, 1H); 8.35 (ddd, J¼8.5, 6.9, 1.2 Hz, 1H);
8.44 (ddd, J¼8.3, 6.9, 1.1 Hz, 1H); 8.56 (dt, J¼8.3, 1.1 Hz, 1H); 8.69
(ddt, J¼8.2, 1.5, 0.9 Hz, 1H); 8.82 (dd, J¼6.8, 0.9 Hz, 1H); 8.86 (d,
J¼5.6 Hz, 1H); 9.08 (ddt, J¼8.5, 1.1, 0.9 Hz, 1H); 9.15 (d, J¼6.8 Hz,
fluoromethanesulfonate (C) (147
m
l, 208.1 mg, 0.96 mmol,1.1 equiv)
and a solution of 2-(pyridin-2-ylethynyl)quinoline (21)33 (201.5 mg,
0.87 mmol, 1 equiv) in toluene (5 mL) gave organic monocation salt
24 as a light gray powder in 61% yield (240.9 mg, 0.53 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.73. Mp 109–110 ꢀC. 1H NMR
(600 MHz, acetone-d6):
d
¼2.53 (t, J¼2.6, 1H); 2.54–2.58 (m, 2H);
1H). 13C NMR (151 MHz, acetone-d6):
81.01; 82.74; 109.33; 124.68; 126.48; 127.40; 128.62; 129.16;
d
¼16.13; 30.02; 61.30; 71.65;
2.60–2.64 (m, 2H); 5.30 (m, 2H); 7.81 (ddd, J¼8.2, 6.8, 1.2, 1H); 7.96
(ddd, J¼8.5, 6.8, 1.4, 1H); 8.06 (d, J¼8.4, 1H); 8.13 (ddt, J¼8.2, 1.4, 0.6,
1H); 8.18 (ddt, J¼8.5, 1.2, 0.9, 1H); 8.39 (ddd, J¼7.7, 6.2, 1.5, 1H); 8.62
(dd, J¼8.4, 1.2, 1H); 8.69 (ddd, J¼8.0, 1.5, 0.6, 1H); 8.87 (td, J¼7.9, 1.5,
1H); 9.43 (ddd, J¼6.2, 1.5, 0.6, 1H). 13C NMR (151 MHz, acetone-d6):
129.90; 130.55; 130.64; 130.88; 132.48; 133.82; 136.88; 137.80;
(cmꢁ1) 1030s,
~
n
137.94; 138.45; 141.08; 141.39; 144.73. IR (KBr):
1156m, 1266vs, 1276vs, 2206m, 3084w. MS (ESI) m/z: 379 (30), 347
[(MꢁOTf)þ] (100), 316 (15), 288 (30). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C25H19N2) calcd: 347.1543, found: 347.1543. Elem. Anal. Calcd for
C26H19F3N2O3S: C, 62.90; H, 3.86; N, 5.64. Found: C, 62.74; H, 3.95;
N, 5.42.
d
¼15.99; 29.78; 60.88; 71.78; 78.37; 82.71; 104.72; 125.51; 129.00;
129.05; 129.12; 129.67; 130.23; 131.79; 134.19; 137.74; 138.10; 140.01,
~
148.17; 148.66; 149.24. IR (KBr):
n
(cmꢁ1) 1030vs; 1168s; 1275s;
1617m; 3079w. MS (ESI) m/z: 297 [(MꢁOTf)þ] (100). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C21H17N2) calcd: 297.1386, found: 297.1388. Elem. Anal.
Calcd for C22H17F3N2O3S$(H2O)0.5 C, 58.02; H, 3.98; F,12.51; N, 6.15; S,
7.04. Found: C, 58.37; H, 3.79; F, 12.56; N, 5.98; S, 6.95.
4.6.4. 1-(But-3-ynyl)-2-(quinolin-2-ylethynyl)pyridinium trifluorome-
thanesulfonate (22). Following the general procedure for organic
monocation formation with a reaction temperature of 25 ꢀC, and
general workup procedure II, neat but-3-ynyl trifluoro-
4.6.7. 2-(But-3-ynyl)-1-(pyridin-2-ylethynyl)isoquinolinium trifluoro-
methanesulfonate (38). Following the general procedure for organic
monocation formation with a reaction temperature of ꢁ10 ꢀC, and
general workup procedure III, neat but-3-ynyl trifluoro-
methanesulfonate (A) (130 ml, 181.5 mg, 0.89 mmol, 1.1 equiv) and
a solution of 2-(pyridin-2-ylethynyl)quinoline (21)33 (188.0 mg,
0.82 mmol, 1 equiv) in toluene (5 mL) gave organic monocation salt
22 as a light gray powder in 75% yield (264.5 mg, 0.61 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.73. 1H NMR (600 MHz,
methanesulfonate (A) (21.0
a solution of 1-(pyridin-2-ylethynyl)isoquinoline (37)33 (31.8 mg,
138 mol, 1 equiv) in toluene (1.5 mL) gave organic monocation salt
38 (>20:1 mixture of regioisomers favoring the desired product as
judged by 1H NMR) in a 49% yield (29.3 mg, 67.8
mol).
mL, 30.8 mg, 153 mmol, 1.1 equiv) and
acetone-d6):
d
¼2.78 (t, J¼2.8 Hz, 1H), 3.33 (td, J¼2.7, 6.6 Hz, 2H),
m
5.37 (t, J¼6.6 Hz, 2H), 7.81 (ddd, J¼8.1, 6.9, 1.2 Hz, 1H), 7.96 (ddd,
J¼8.5, 6.9, 1.5 Hz, 1H), 8.06 (d, J¼8.5 Hz, 1H), 8.13 (ddt, J¼8.1, 1.5,
0.7 Hz, 1H), 8.18 (ddt, J¼8.5, 1.2, 0.9 Hz, 1H), 8.42 (ddd, J¼7.8, 6.2,
1.5 Hz, 1H), 8.61 (dd, J¼8.5, 1.2 Hz, 1H), 8.72 (ddd, J¼8.0, 1.5, 0.6 Hz,
1H), 8.92 (td, J¼7.9, 1.5 Hz, 1H), 9.43 (ddd, J¼6.2, 1.5, 0.6 Hz, 1H). 13C
m
Rf [SiO2, Stoddart’s magic mixture]: 0.70. Mp 124–126 ꢀC. 1H
NMR (400 MHz, acetone-d6): 2.71 (t, J¼2.7 Hz, 1H); 3.35 (td, J¼6.7,
2.7 Hz, 2H); 5.47 (t, J¼6.6 Hz, 2H); 7.72 (ddd, J¼7.7, 4.8, 1.3 Hz, 1H);
8.11 (td, J¼7.7, 1.7 Hz, 1H); 8.21 (dt, J¼7.8, 1.1 Hz, 1H); 8.31 (ddd,
J¼8.3, 6.9, 1.3 Hz, 1H); 8.42 (ddd, J¼8.2, 7.0, 1.3 Hz, 1H); 8.53 (broad
d, J¼8.2 Hz, 1H); 8.78 (broad d, J¼6.7 Hz, 1H); 8.89 (ddd, J¼4.8, 1.7,
1.0 Hz, 1H); 8.98 (dq, J¼8.4, 0.9 Hz, 1H); 9.09 (d, J¼6.8 Hz, 1H). 13C
NMR (100 MHz, acetone-d6): 21.36; 60.57; 75.23; 77.79; 79.88;
100.62; 127.52; 127.88; 129.83; 130.74; 131.15; 134.48; 138.50;
138.69; 138.87; 139.21; 141.40; 141.86; 151.88; 152.83. IR (thin
NMR (151 MHz, acetone-d6):
d
¼20.54, 59.57, 74.89, 78.27, 78.93,
105.04, 125.59, 128.78, 129.00, 129.05, 129.67, 130.21, 131.78, 134.ꢁ017,
~
137.69, 138.06, 140.99, 147.08, 148.36, 149.21. IR (KBr):
n
(cm
)
1030s; 1168s; 1275s; 1618m; 3082w. MS (ESI) m/z: 283 [(MꢁOTf)þ]
(100). HRMS (ESI) m/z: [(MꢁOTf)þ] (C20H15N2) calcd: 283.1230,
found: 283.1231. Elem. Anal. Calcd for C21H15F3N2O3S: C, 50.00; H,
3.42; N, 4.32. Found: C, 49.87; H, 3.35; N, 4.14.

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3543
~
film):
n
(cmꢁ1) 1027s; 1156s; 1221s; 1259s; 1438m; 1510w; 1562m;
4.11. Organic dication formation, general workup
procedure II (9)
1620m; 2212m; 3251m. MS (ESI) m/z: 283.2 [(MꢁOTf)þ] (100).
HRMS (ESI) m/z: [(MꢁOTf)þ] (C20H15N2) calcd: 283.1230, found:
283.1235. Elem. Anal. Calcd for C21H15F3N2O3S: C, 58.33; H, 3.50; N,
6.48. Found C, 58.10; H, 3.52; N, 6.20.
The reaction mixture was diluted with water and stirred vigor-
ously until all precipitate had dissolved. The aqueous layer was
separated and all volatiles were removed in vacuo. Ethyl acetate
was added to the resultant residue and this mixture, contained in
a RBF, was immersed in an ultrasonic bath and sonicated for 1 min
giving a fine suspension. The supernatant solution was separated
from the fine powder via centrifuge and then removed via de-
cantation. The sonication treatment with ethyl acetate was re-
peated (1ꢂ), the product was transferred to a vial and dried under
vacuum (2 mbar) to give the organic dication salt.
4.6.8. 2-(Pent-4-ynyl)-1-(pyridin-2-ylethynyl)isoquinolinium trifluoro-
methanesulfonate (41). Following the general procedure for organic
monocation formation with a reaction temperature of ꢁ10 ꢀC, and
general workup procedure III, neat pent-4-ynyl trifluoro-
methanesulfonate (C) (46 mL, 59.1 mg, 0.27 mmol, 1.1 equiv) and
a solution of 1-(pyridin-2-ylethynyl)isoquinoline (37)33 (57.2 mg,
0.25 mmol, 1 equiv) in dry toluene (2.75 mL) gave organic mono-
cation salt 41 (>20:1 mixture of regioisomers favoring the desired
product as judged by 1H NMR) in a 58% yield (65.5 mg, 144
mmol).
4.12. Organic dication formation, general workup
procedure III (25–30)
Rf [SiO2, Stoddart’s magic mixture]: 0.71. Mp 117–119 ꢀC. 1H NMR
(400 MHz, acetone-d6): 2.47 (t, J¼2.6 Hz, 1H); 2.52–2.64 (m, 4H);
5.38 (t, J¼7.3 Hz, 2H); 7.70 (ddd, J¼7.7, 4.8, 1.3 Hz, 1H); 8.09 (td,
J¼7.7, 1.7 Hz, 1H); 8.21 (dt, J¼7.8, 1.1 Hz, 1H); 8.31 (ddd, J¼8.3, 6.9,
1.3 Hz, 1H); 8.42 (ddd, J¼8.2, 7.0, 1.3 Hz, 1H); 8.53 (broad d,
J¼8.2 Hz, 1H); 8.78 (broad d, J¼6.7 Hz, 1H); 8.89 (ddd, J¼4.8, 1.7,
1.0 Hz, 1H); 8.98 (dq, J¼8.4, 0.9 Hz, 1H); 9.09 (d, J¼6.8 Hz, 1H). 13C
NMR (100 MHz, acetone-d6): 16.85; 61.80; 72.35; 77.83; 83.54;
103.25; 127.85; 129.79; 130.61; 131.06; 131.41; 134.37; 138.36;
The reaction mixture was cooled to rt and concentrated in vacuo
to give a brown residue. Diethyl ether was added to the residue and
this mixture, contained in a RBF, was immersed in an ultrasonic
bath and sonicated for 1 min. The supernatant solution was sepa-
rated via decantation. DCM and water were added to the remaining
residue and the mixture was stirred vigorously until all material
dissolved. The aqueous layer was separated, washed with DCM
(3ꢂ) and concentrated in vacuo to give a red glass. Diethyl ether/
tetrahydrofuran 1:1 was added to the residue and this mixture,
contained in a RBF, was immersed in an ultrasonic bath and soni-
cated for 1 min. The supernatant solution was separated from the
precipitate via centrifuge and then removed via decantation. This
washing procedure was repeated (2ꢂ) and the product was then
dried under vacuum (2 mbar) to give the organic dication salt.
138.61; 138.71; 139.10; 140.92; 141.43; 150.35; 152.86; one carbon
peak likely obscured by (CD3)2CO peak. IR (thin film):
ꢁ1
~
n
(cm
)
1027s; 1151s; 1224s; 1260s; 1438m; 1562m; 1575m; 1603m;
1618m; 2217m; 3237m. MS (ESI) m/z: 297.2 [(MꢁOTf)þ] (100).
HRMS (ESI) m/z: [(MꢁOTf)þ] (C21H17N2) calcd: 297.1386, found:
297.1387. Elem. Anal. Calcd for C22H17F3N2O3S$(H2O)0.5 C, 58.02; H,
3.98; N, 6.15. Found: C, 58.40; H, 3.69; N, 6.13.
4.7. Synthesis of organic dications
4.13. Organic dication formation, general workup procedure
IV (39, 42)
Organic dications were synthesized by one of two general pro-
cedures which was followed by one of four workup procedures.
The reaction mixture was diluted with water and stirred vigor-
ously until all the precipitate had dissolved. The aqueous layer was
separated, washed with DCM (3ꢂ) and concentrated in vacuo to
give the organic dication salt.
4.8. Organic dication formation, general procedure I
(7–13, 39, 42)
The desired alkynyltriflate (A–F) (4–4.5 equiv) was added to
a stirred solution of organic monocation salt (1 equiv) in dry DCM
at 25 ꢀC under Ar. The flask was protected from light with Al-foil
and the reaction stirred at 25 ꢀC for 1–4 days.
4.13.1. 2-(But-3-ynyl)-1-((2-(pent-3-ynyl)isoquinolinium-1-yl)ethy-
nyl)isoquinolinium trifluoromethanesulfonate (7). Following the
general procedure for organic dication formation I with a reaction
time of four days, and general workup procedure I, neat pent-3-
ynyl trifluoromethanesulfonate (D) (176
ml, 237.1 mg, 1.097 mmol,
4.9. Organic dication formation, general procedure II (25–30)
4 equiv) and a solution of organic monocation salt 4 (132.3 mg,
0.274 mmol, 1 equiv) in DCM (8 mL) gave organic dication salt 7 as
a light yellow powder in 81% yield (155.2 mg, 0.222 mmol).
The desired alkynyltriflate (A–F) (1–1.1 equiv) was added to
a solution of organic monocation salt (1 equiv) in dry DCM con-
tained in a sealable Carius tube stirred under Ar. The reaction vessel
was sealed and the reaction mixture stirred 24 h at 50 ꢀC. The re-
action was cooled to 25 ꢀC, a second portion of the same alkynyl-
triflate (A–F) (1–1.1 equiv) was added and the reaction stirred
a further 24 h at 50 ꢀC.
Mp 223–225 ꢀC. 1H NMR (600 MHz, acetone-d6):
d¼1.75 (t,
J¼2.5 Hz, 3H), 2.83 (t, J¼2.7 Hz, 1H); 3.30 (tq, J¼6.5, 2.5 Hz, 2H);
3.41 (td, J¼6.5, 2.7 Hz, 2H); 5.57 (t, J¼6.5 Hz, 2H); 5.65 (t, J¼6.5 Hz,
2H); 8.31 (ddd, J¼8.6, 7.1, 1.2 Hz, 1H); 8.33 (ddd, J¼8.6, 7.1, 1.2
Hz, 1H); 8.47 (ddd, J¼8.3, 7.1, 1.1 Hz, 1H); 8.48 (ddd, J¼8.3, 7.1, 1.1 Hz,
1H); 8.63 (dt, J¼8.3, 1.0 Hz, 1H); 8.65 (dt, J¼8.3, 1.0 Hz, 1H); 9.00
(broad d, J¼6.8 Hz, 1H); 9.02 (broad d, J¼6.9 Hz, 1H); 9.17 (dq, J¼8.6,
1.0 Hz, 1H); 9.19 (dq, J¼8.6, 1.0 Hz, 1H); 9.27 (d, J¼6.8 Hz, 1H); 9.29
4.10. Organic dication formation, general workup procedure
I (7, 8, 10–13)
(d, J¼6.9 Hz, 1H). 13C NMR (151 MHz, acetone-d6):
¼3.19; 21.35;
d
21.78; 60.58; 61.26; 74.39; 75.28; 79.48; 82.04; 96.10; 96.38;
128.70; 128.93; 129.23; 129.27; 130.03; 130.05; 131.09; 131.10;
134.33; 134.36; 138.42; 138.48; 138.55; 138.60; 138.83; 138.87;
(cmꢁ1) 1031s, 1262vs, 1276s, 1623m,
~
138.91; 139.10. IR (KBr):
n
All volatiles were removed in vacuo from the reaction mixture to
give a brown residue. Ethyl acetate was added tothe residue and this
mixture, contained in a RBF, was immersed in an ultrasonic bath and
sonicated for 1 min giving a fine suspension. The supernatant so-
lution was separated from the fine powder via centrifuge and then
removed via decantation. The sonication treatment with ethyl ac-
etate was repeated (2ꢂ), the product was transferred to a vial and
dried under vacuum (2 mbar) to give the organic dication salt.
3082w. MS (ESI) m/z: 549 [(MꢁOTf)þ] (13), 446 (72), 417 (100), 400
(34), 333 (19), 200 [(M-2OTf)2þ] (16). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C30H24F3N2O3S) calcd: 549.1454, found: 549.1464. Elem. Anal.
Calcd for C31H24F6N2O6S2: C, 53.29; H, 3.46; N, 4.01. Found: C,
53.05; H, 3.51; N, 3.81.

3544
L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
4.13.2. 2-(But-3-ynyl)-1-((2-(tetradec-3-ynyl)isoquinolinium-1-yl)
ethynyl)isoquinolinium trifluoromethanesulfonate (8). Following the
general procedure for organic dication formation I with a reaction
time of 63 h, and general workup procedure I, neat tetradec-3-ynyl
J¼8.4, 1.0 Hz, 1H); 8.64 (dt, J¼8.4, 1.0 Hz, 1H); 8.98 (dd, J¼6.9, 0.8 Hz,
1H); 9.01 (dd, J¼6.9, 0.8 Hz, 1H); 9.16 (dq, J¼8.6, 0.9 Hz, 1H); 9.17 (dq,
J¼8.6, 0.9 Hz, 1H); 9.27 (d, J¼6.8 Hz, 1H); 9.29 (d, J¼6.8 Hz, 1H). 13C
NMR (100 MHz, acetone-d6):
d¼18.54; 21.48; 26.15; 31.20; 60.78;
trifluoromethanesulfonate (E) (150
ml, 164.0 mg, 0.479 mmol,
62.79; 70.77; 75.35; 79.62; 84.18; 96.04; 96.88; 129.05; 129.08;
129.29; 129.32; 129.39; 130.17; 131.30; 131.61; 134.39; 134.59;
138.36; 138.43; 138.57; 138.59; 138.75; 138.88; 138.97; 139.13. IR
~
4.6 equiv) and a solution of organic monocation salt 4 (49.8 mg,
0.103 mmol, 1 equiv) in DCM (8 mL) gave organic dication salt 8 as
a light brown powder in 61% yield (51.8 mg, 0.063 mmol).
(KBr):
n
(cmꢁ1) 1031s, 1262vs, 1607m, 3086w. MS (ESI) m/z: 563
Mp 154–156 ꢀC. 1H NMR (600 MHz, acetone-d6):
d¼0.91 (t,
[(MꢁOTf)þ] (75), 414 (100), 333 (10), 207 [(M-2OTf)2þ] (3). HRMS (ESI)
J¼7.2 Hz, 3H); 1.13–1.29 (m, 14H); 1.30–1.35 (m, 2H), 2.16 (tt, J¼7.1,
2.4 Hz, 2H); 2.84 (t, J¼2.6 Hz, 1H); 3.36 (tt, J¼6.5, 2.4 Hz, 2H); 3.41
(td, J¼6.6, 2.6 Hz, 2H); 5.60 (t, J¼6.5 Hz, 2H); 5.65 (t, J¼6.6 Hz, 2H);
8.31–8.35 (m, 2H); 8.47–8.51 (m, 2H); 8.63–8.66 (m, 2H); 9.01–9.03
(m, 2H); 9.18 (dq, J¼8.6, 1.0 Hz, 1H); 9.19 (dq, J¼8.6, 1.0 Hz, 1H); 9.28
(d, J¼6.8 Hz, 1H); 9.29 (d, J¼6.8 Hz, 1H). 13C NMR (151 MHz, ace-
m/z: [(MꢁOTf)þ] (C31H26F3N2O3S) calcd: 563.1611, found: 563.1607.
4.13.5. 2-(Pent-4-ynyl)-1-((2-(4-phenylbut-3-ynyl)isoquinolinium-1-
yl)ethynyl)isoquinolinium trifluoromethanesulfonate (11). Following
the general procedure for organic dication formation I with a reaction
time of 67 h and general workup procedure I, neat pent-4-ynyl tri-
tone-d6):
d
¼14.31; 18.99; 21.38; 21.85; 23.27; 29.28; 29.45; 29.73;
fluoromethanesulfonate (C) (63 ml, 87.4 mg, 0.405 mmol, 4.5 equiv)
29.98; 30.24; 30.31; 60.60; 61.20; 75.32; 79.47; 86.64; 96.20; 96.38;
128.71; 128.95; 129.25; 129.30; 130.02; 130.05; 131.06; 131.09;
134.37; 134.41; 138.45; 138.54; 138.61; 138.86; 138.92; 139.06; one
carbon peak likely obscured by (CHD2)(CD3)CO peak, the three
peaks at 75.32, 138.54, and 138.61 each represent two overlapping
and a solution of monocation 5 (50.2 mg, 0.090 mmol, 1 equiv) in
DCM (10 mL) gave organic dication salt 11 as a yellow powder in 58%
yield (40.9 mg, 0.053 mmol).
Mp 85–87 ꢀC. 1H NMR (600 MHz, acetone-d6):
d
¼2.37 (t,
J¼2.7 Hz, 1H); 2.54–2.57 (m, 2H); 2.63–2.69 (m, 2H); 3.65 (t,
J¼6.5 Hz, 2H); 5.53–5.57 (m, 2H); 5.75 (t, J¼6.5 Hz, 2H); 7.31–7.35
(m, 4H); 7.37–7.40 (m, 1H); 8.19 (ddd, J¼8.6, 7.0, 1.1 Hz, 1H); 8.33
(ddd, J¼8.6, 6.9, 1.1 Hz, 1H); 8.43 (ddd, J¼8.4, 7.0, 1.1 Hz, 1H); 8.49
(ddd, J¼8.4, 6.9, 1.1 Hz, 1H); 8.60 (dt, J¼8.4, 1.0 Hz, 1H); 8.65 (dt,
J¼8.4,1.0 Hz,1H); 8.97 (dd, J¼6.8, 0.9 Hz,1H); 9.06 (dd, J¼6.8, 0.9 Hz,
1H); 9.11 (dq, J¼8.6, 1.0 Hz, 1H); 9.18 (dq, J¼8.6, 0.9 Hz, 1H); 9.24 (d,
J¼6.8 Hz, 1H); 9.39 (d, J¼6.8 Hz, 1H). 13C NMR (151 MHz, acetone-
carbon signals. IR (KBr): (cmꢁ1) 1032s, 1159s, 1261vs, 1277vs,
~
n
1625m, 3083w. MS (ESI) m/z: 675 [(MꢁOTf)þ] (22), 572 (100), 526
(33), 263 [(M-2OTf)2þ
]
(72). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C39H42F3N2O3S) calcd: 675.2863, found: 675.2866.
4.13.3. 2-(But-3-ynyl)-1-((2-(4-phenylbut-3-ynyl)isoquinolinium-1-
yl)ethynyl)isoquinolinium trifluoromethanesulfonate (9). Following
the general procedure for organic dication formation I with a re-
action time of 92 h, and general workup procedure II, neat 4-phe-
d6):
d
¼16.03; 22.37; 30.41; 60.94; 61.87; 71.75; 82.94; 85.13; 85.80;
95.96; 96.58; 123.21; 128.90; 129.18; 129.24; 129.37; 129.41;
129.49; 129.88; 129.92; 131.16; 131.34; 132.18; 134.20; 134.45;
nylbut-3-ynyl trifluoromethanesulfonate (B) (99 ml, 130.5 mg,
0.469 mmol, 4.5 equiv) and a solution of organic monocation salt 4
(50.3 mg, 0.104 mmol,1 equiv) in DCM (8 mL) gave organic dication
salt 9 as a light orange powder in 62% yield (49.1 mg, 0.065 mmol).
138.30; 138.62; 138.66; 138.74; 138.91; 139.02; 139.08; the peak at
ꢁ1
~
138.30 represents two overlapping carbon signals. IR (KBr):
n
(cm
)
1031s,1262vs,1275vs,1275vs, 3084w. MS (ESI) m/z: 625 [(MꢁOTf)þ]
(75), 476 (84), 409 (100), 238 [(M-2OTf)2þ] (90). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C36H28F3N2O3S) calcd: 625.1767, found: 625.1768.
Mp 96–98 ꢀC. 1H NMR (600 MHz, acetone-d6):
d¼2.84 (t,
J¼2.7 Hz,1H); 3.37 (td, J¼6.5, 2.7 Hz, 2H); 3.65 (t, J¼6.3 Hz, 2H); 5.63
(t, J¼6.5 Hz, 2H); 5.75 (t, J¼6.3 Hz, 2H); 7.30–7.36 (m, 4H); 7.37–7.41
(m,1H); 8.21 (ddd, J¼8.6, 6.9,1.1 Hz,1H); 8.33 (ddd, J¼8.6, 7.0,1.2 Hz,
1H); 8.46 (ddd, J¼8.3, 6.9, 1.1 Hz, 1H); 8.48 (ddd, J¼8.3, 7.0, 1.1 Hz,
1H); 8.63 (dt, J¼8.3, 1.0 Hz, 1H); 8.65 (dt, J¼8.3,1.0 Hz,1H); 9.01 (dd,
J¼6.8, 0.8 Hz,1H); 9.06 (dd, J¼6.8, 0.8 Hz,1H); 9.13 (dq, J¼8.6,1.0 Hz,
1H); 9.19 (dq, J¼8.6, 1.0 Hz, 1H); 9.28 (d, J¼6.8 Hz, 1H); 9.40 (d,
4.13.6. 2-(But-3-ynyl)-1-((2-(pent-4-ynyl)isoquinolinium-1-yl)ethy-
nyl)isoquinolinium trifluoromethanesulfonate (12). Following the
general procedure for organic dication formation I with a reaction
time of 54 h and general workup procedure I, neat but-3-ynyl tri-
fluoromethanesulfonate (A) (86 ml, 125.6 mg, 0.621 mmol, 4 equiv)
J¼6.8 Hz, 1H). 13C NMR (151 MHz, acetone-d6):
d
¼21.34; 22.39;
and a solution of organic monocation salt 6 (77.1 mg, 0.155 mmol,
1 equiv) in DCM (9 mL) gave organic dication salt 12 as a light
yellow powder in 84% yield (91.1 mg, 0.130 mmol).
60.57; 60.95; 75.34; 79.48; 85.21; 85.83; 96.24; 96.37; 123.22;
128.86; 128.92; 129.25; 129.33; 129.43; 129.51; 130.00; 130.02;
131.04; 131.17; 132.17; 134.33; 134.44; 138.41; 138.60; 138.61;
138.96; 139.03; 139.06; the two peaks at 138.96, and 138.61 each
~
Mp 176–178 ꢀC. 1H NMR (600 MHz, acetone-d6):
d
¼2.36 (t,
J¼2.7 Hz, 1H); 2.56–2.58 (m, 2H); 2.65–2.71 (m, 2H); 2.83 (t, J¼2.7,
1H); 3.40 (td, J¼6.6, 2.7 Hz, 2H); 5.56 (t, J¼6.7 Hz, 2H); 5.65 (t,
J¼6.6 Hz, 2H); 8.29 (ddd, J¼8.6, 6.9,1.0 Hz,1H); 8.32 (ddd, J¼8.7, 7.0,
1.1 Hz,1H); 8.45 (broad t, J¼7.5 Hz,1H); 8.48 (broad t, J¼7.6 Hz, 1H);
8.61 (dt, J¼8.4,1.0 Hz,1H); 8.64 (dt, J¼8.3,1.0 Hz,1H); 8.98 (broad d,
J¼6.8 Hz, 1H); 9.02 (broad d, J¼6.8 Hz, 1H); 9.15 (broad d, J¼8.7 Hz,
1H); 9.17 (broad d, J¼8.7 Hz, 1H); 9.25 (d, J¼6.8 Hz, 1H); 9.29 (d,
represent two overlapping carbon signals. IR (KBr):
n
(cmꢁ1) 1030s,
1262vs, 1273vs, 3084w. MS (ESI) m/z: 611 [(MꢁOTf)þ] (14), 525
(100), 462 (42), 231 [(M-2OTf)2þ] (18). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C35H26F3N2O3S) calcd: 611.1611, found: 611.1618.
4.13.4. 2-(But-3-ynyl)-1-((2-(hex-5-ynyl)isoquinolinium-1-yl)ethy-
nyl)isoquinolinium trifluoromethanesulfonate (10). Following the
general procedure for organic dication formation I with a reaction
time of one day and a reaction temperature of 35 ꢀC and general
workup procedure I, neat hex-5-ynyl trifluoromethanesulfonate (F)
J¼6.8 Hz, 1H). 13C NMR (151 MHz, acetone-d6):
¼16.04; 21.32;
d
30.40; 60.63; 61.89; 71.75; 75.25; 79.42; 82.96; 95.90; 96.60;
128.93; 129.18; 129.22; 129.29; 129.98; 130.03; 131.09; 131.39;
134.26; 134.40; 138.33; 138.49; 138.62; 138.75; 138.96; 139.12; the
two peaks at 138.33 and 138.75 each represent two overlapping
(cmꢁ1) 1031s, 1159s, 1266vs, 1623m,
~
carbon signals. IR (KBr):
n
(83 ml, 110.6 mg, 0.480 mmol, 4.5 equiv) and a solution of organic
monocation salt 4 (51.5 mg, 0.107 mmol, 1 equiv) in DCM (8 mL)
gave organic dication salt 10 as a light brown powder in 72% yield
(54.5 mg, 0.077 mmol).
3083w. MS (ESI) m/z: 549 [(MꢁOTf)þ] (100), 400 (56), 200 [(M-
2OTf)2þ] (33). HRMS (ESI) m/z: [(MꢁOTf)þ] (C30H24F3N2O3S) calcd:
549.1454, found: 549.1446. Elem. Anal. Calcd for C31H24F6N2O6S2:
C, 53.29; H, 3.46; N, 4.01. Found: C, 53.02; H, 3.46; N, 3.78.
1H NMR (400 MHz, acetone-d6):
d
¼1.84 (m, 2H), 2.32 (td, J¼7.0,
2.7 Hz, 2H); 2.39 (t, J¼2.7 Hz, 1H); 2.56 (m, 2H); 2.83 (t, J¼2.7 Hz, 1H);
3.41 (td, J¼6.6, 2.7 Hz, 2H); 5.51 (t, J¼7.5 Hz, 2H); 5.64 (t, J¼6.6 Hz, 2H);
8.29 (ddd, J¼8.6, 7.0,1.2 Hz, 1H); 8.33 (ddd, J¼8.5, 7.0, 1.2 Hz, 1H); 8.45
(ddd, J¼8.3, 7.0, 1.2 Hz, 1H); 8.48 (ddd, J¼8.3, 7.0, 1.2 Hz, 1H); 8.61 (dt,
4.13.7. 2-(Pent-3-ynyl)-1-((2-(pent-4-ynyl)isoquinolinium-1-yl)-
ethynyl)isoquinolinium trifluoromethanesulfonate (13). Following the

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3545
general procedure for organic dication formation I with a reaction
time of 54 h and general workup procedure I, neat pent-3-ynyl
75.44; 79.05; 83.31; 93.90; 94.41; 120.07; 128.51; 130.79; 131.73;
132.12; 132.20; 139.16; 135.46; 135.55; 138.52; 140.61; 147.54;
(cmꢁ1) 1030s; 1161s, 1261vs; 1619m;
~
trifluoromethanesulfonate (D) (100
m
l, 134.5 mg, 0.6222 mmol,
148.33; 149.28. IR (KBr):
n
4 equiv) and a solution of organic monocation salt 6 (77.2 mg,
0.156 mmol, 1 equiv) in DCM (9 mL) gave organic dication salt 13 as
a light yellow powder in 81% yield (89.8 mg, 0.126 mmol).
3091w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (95). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298, found: 499.1293.
Mp 178–180 ꢀC. 1H NMR (600 MHz, acetone-d6):
d¼1.75 (t,
4.13.10. 1-(But-3-ynyl)-2-((1-(pent-3-ynyl)pyridinium-2-yl)ethy-
nyl)quinolinium trifluoromethanesulfonate (27). Following the gen-
eral procedure for organic dication formation II and general workup
procedure III, two portions of neat but-3-ynyl tri-
J¼2.6, 3H), 2.36 (t, J¼2.6 Hz, 1H); 2.56–2.60 (m, 2H); 2.65–2.71 (m,
2H); 3.31 (tq, J¼6.6, 2.6 Hz, 2H); 5.55–5.58 (m, 4H); 8.30 (ddd,
J¼8.6, 6.9, 1.2 Hz, 1H); 8.32 (ddd, J¼8.6, 7.0, 1.2 Hz, 1H); 8.46 (ddd,
J¼8.3, 6.9, 1.2 Hz, 1H); 8.48 (ddd, J¼8.2, 7.0, 1.2 Hz, 1H); 8.62 (dt,
J¼8.3,1.0 Hz,1H); 8.64 (dt, J¼8.2,1.0 Hz,1H); 8.98 (dd, J¼6.8, 0.9 Hz,
1H); 9.01 (dd, J¼6.8, 0.9 Hz, 1H); 9.16 (m, 2H); 9.25 (d, J¼6.8 Hz,
fluoromethanesulfonate (A) (each portion: 35 mL, 48.5 mg,
0.24 mmol, 1.1 equiv) and a solution of organic monocation salt 23
(97.5 mg, 0.21 mmol, 1 equiv) in DCM (2 mL) gave pure organic
dication salt 27 as a light red solid in 56% yield (79.5 mg, 0.12 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.41. Mp 99–103 ꢀC. 1H NMR
1H); 9.27 (d, J¼6.8 Hz,1H). 13C NMR (151 MHz, acetone-d6):
¼3.21;
d
16.04; 21.77; 30.43; 61.28; 61.87; 71.72; 74.31; 82.02; 82.95; 95.98;
96.40; 128.73; 129.20; 129.23; 129.28; 129.89; 129.94; 131.10;
131.39; 134.24; 134.35; 138.32; 138.51; 138.62; 138.73; 138.93;
139.11; the peak at 138.32 represents three overlapping carbon
~
(600 MHz, acetone-d6):
d
¼ 1.78 (t, J¼2.5, 3H); 2.80 (t, J¼2.7, 1H);
d
3.24 (tq, J¼6.4, 2.5, 2H); 3.41 (td, J¼6.8, 2.7, 2H); 5.38 (t, J¼6.4, 2H);
5.92 (t, J¼6.8, 2H); 8.27 (ddd, J¼8.2, 7.0, 0.9, 1H); 8.53 (ddd, J¼9.1,
7.0, 1.5, 1H); 8.57 (ddd, J¼7.7, 6.2, 1.8, 1H); 8.69 (ddt, J¼8.2, 1.5, 0.5,
1H); 8.88 (d, J¼8.5, 1H); 8.96 (dq, J¼9.1, 0.9, 1H); 8.98 (ddd, J¼7.9,
1.8, 0.6, 1H); 9.01 (td, J¼7.8, 1.4, 1H); 9.53 (ddd, J¼6.2, 1.4, 0.6, 1H);
signals. IR (KBr):
n
(cmꢁ1) 1031s, 1262vs, 3083w. MS (ESI) m/z: 563
[(MꢁOTf)þ] (5), 414 (8), 347 (100), 207 [(M-2OTf)2þ] (28). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C31H26F3N2O3S) calcd: 563.1616, found:
563.1604. Elem. Anal. Calcd for C32H26F6N2O6S2: C, 53.93; H, 3.68;
N, 3.93. Found: C, 53.61; H, 3.73; N, 3.73.
9.59 (dd, J¼8.5, 1.2, 1H). 13C NMR (151 MHz, acetone-d6):
¼3.15;
d
20.00; 21.60; 55.23; 60.84; 73.97; 75.55; 79.46; 82.40; 93.89; 94.83;
120.33; 128.15; 130.64; 131.56; 132.18; 132.36; 135.42; 135.50;
ꢁ1
~
4.13.8. 2-((1-(But-3-ynyl)pyridinium-2-yl)ethynyl)-1-(pent-3-ynyl)-
quinolinium trifluoromethanesulfonate (25). Following the general
procedure for organic dication formation II and general workup
procedure III, two portions of neat pent-3-ynyl trifluoro-
138.62; 139.54; 140.41; 147.36; 148.52; 149.12. IR (KBr):
n
(cm
)
1031s; 1261vs; 1616m; 3088w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (55).
HRMS (ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298,
found: 499.1297. Elem. Anal. Calcd for C27H22F6N2O6S2: C, 50.00; H,
3.42; N, 4.32. Found: C, 49.87; H, 3.35; N, 4.14.
methanesulfonate (D) (each portion: 41 mL, 53.9 mg, 0.25 mmol,
1.1 equiv) and a solution of organic monocation salt 22 (108.8 mg,
0.22 mmol,1 equiv) in DCM (2 mL) gave pure organic dication salt 25
as a light red powder in 51% yield (74.4 mg, 0.11 mmol).
4.13.11. 2-((1-(Pent-3-ynyl)pyridinium-2-yl)ethynyl)-1-(pent-4-
ynyl)quinolinium trifluoromethanesulfonate (28). Following the
general procedure for organic dication formation II and general
workup procedure III, two portions of neat pent-4-ynyl trifluoro-
Rf [SiO2, Stoddart’s magic mixture]: 0.41. Mp 104–108 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d
¼1.67 (t, J¼2.6 Hz, 3H); 2.83 (t,
J¼2.7 Hz, 1H); 3.31 (tq, J¼6.7, 2.6 Hz, 2H); 3.37 (td, J¼6.5, 2.7 Hz,
2H); 5.46 (t, J¼6.5 Hz, 2H); 5.86 (t, J¼6.7 Hz, 2H); 8.26 (ddd, J¼8.1,
7.0, 0.9 Hz, 1H); 8.52 (ddd, J¼9.1, 7.0, 1.5 Hz, 1H); 8.58 (ddd, J¼7.8,
6.1, 1.8 Hz, 1H); 8.68 (ddt, J¼8.1, 1.5, 0.5 Hz, 1H); 8.89 (d, J¼8.5 Hz,
1H); 8.95 (dq, J¼9.1, 0.9 Hz, 1H); 8.99 (ddd, J¼8.0, 1.8, 0.6 Hz, 1H);
9.02 (td, J¼7.9, 1.4 Hz, 1H); 9.55 (ddd, J¼6.1, 1.4, 0.6 Hz, 1H); 9.57
methanesulfonate (C) (each portion: 39 mL, 55.2 mg, 0.25 mmol,
1 equiv) and a solution of organic monocation salt 23 (114.0 mg,
0.25 mmol,1 equiv) in DCM (2 mL) gave pure organic dication salt 28
as a brown oil in 51% yield (87.0 mg, 0.11 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.41. 1H NMR (600 MHz, ac-
etone-d6):
d
¼1.77 (t, J¼2.5 Hz, 3H); 2.58 (t, J¼2.7 Hz, 1H); 2.59–2.63
(dd, J¼8.5, 0.9 Hz, 1H). 13C NMR (151 MHz, acetone-d6):
d¼3.15;
(m, 2H); 2.74 (td, J¼6.7, 2.7 Hz, 2H); 3.24 (tq, J¼6.5, 2.5 Hz, 2H); 5.38
(t, J¼6.5 Hz, 2H); 5.77 (m, 2H); 8.24 (ddd, J¼8.2, 7.0, 0.9 Hz,1H); 8.51
(ddd, J¼9.1, 7.0, 1.5 Hz, 1H); 8.56 (ddd, J¼7.6, 6.2, 1.8 Hz, 1H); 8.66
(ddt, J¼8.2, 1.5, 0.5 Hz, 1H); 8.84 (d, J¼8.6 Hz, 1H); 8.90 (dq, J¼9.1,
0.8 Hz, 1H); 8.99 (ddd, J¼8.0, 1.8, 0.8 Hz, 1H); 9.01 (td, J¼7.9, 1.4 Hz,
1H); 9.52 (dt, J¼6.2,1.0 Hz,1H); 9.53 (dd, J¼8.6,1.0 Hz,1H). 13C NMR
20.50; 21.08; 60.18; 55.77; 74.58; 75.45; 79.04; 82.47; 94.19; 94.34;
120.36; 128.11; 130.76; 131.53; 132.09; 132.33; 135.58; 135.61;
ꢁ1
~
138.40; 139.33; 140.43; 147.52; 148.62; 149.21. IR (KBr):
n
(cm
)
1031s; 1261vs; 1620m; 3070w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (91).
HRMS (ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298,
found: 499.1297. Elem. Anal. Calcd for C27H22F6N2O6S2$(H2O)0.5: C,
49.32; H, 3.53; N, 4.26. Found: C, 49.26; H, 3.31; N, 4.13.
(151 MHz, acetone-d6):
d¼3.15; 16.26; 21.51; 28.95; 56.49; 60.83;
71.80; 73.94; 82.37; 83.31; 93.64; 94.50; 120.08; 128.49; 130.66;
131.72; 132.11; 132.17; 135.31; 135.47; 138.50; 139.16; 140.61;
(cmꢁ1) 1030s, 1159s, 1261vs;
~
4.13.9. 2-((1-(But-3-ynyl)pyridinium-2-yl)ethynyl)-1-(pent-4-ynyl)-
quinolinium trifluoromethanesulfonate (26). Following the general
procedure for organic dication formation II and general workup
procedure III, two portions of neat pent-4-ynyl trifluoro-
147.39; 148.34; 149.20. IR (KBr):
n
1617m; 3089w. MS (ESI) m/z: 513 [(MꢁOTf)þ] (71). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C27H24F3N2O3S) calcd: 513.1354, found: 513.1450.
methanesulfonate (C) (each portion: 31
m
L, 43.5 mg, 0.20 mmol,
4.13.12. 1-(But-3-ynyl)-2-((1-(pent-4-ynyl)pyridinium-2-yl)ethynyl)-
quinolinium trifluoromethanesulfonate (29). Following the general
procedure for organic dication formation II and general workup
procedure III, two portions of neat but-3-ynyl trifluoro-
1 equiv) and a solution of monocation 22 (87.0 mg, 0.20 mmol,
1 equiv) in DCM (2 mL) gave pure organic dication salt 26 as a brown
oil in 53% yield (69.6 mg, 0.11 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.41. 1H NMR (600 MHz, ace-
methanesulfonate (A) (each portion: 36 mL, 49.3 mg, 0.24 mmol,
tone-d6):
d
¼2.57 (t, J¼2.7 Hz, 1H); 2.58–2.63 (m, 2H); 2.72 (td, J¼6.6,
1 equiv) and a solution of organic monocation salt 24 (98.1 mg,
0.24 mmol,1 equiv) in DCM (2 mL) gave pure organic dication salt 29
as a light brown solid in 46% yield (72.4 mg, 0.11 mmol).
2.7 Hz, 2H); 2.81 (t, J¼2.7 Hz,1H); 3.35 (td, J¼6.5, 2.7 Hz, 2H); 5.45 (t,
J¼6.5 Hz, 2H); 5.77 (m, 2H); 8.24 (ddd, J¼8.2, 7.0, 0.8 Hz, 1H); 8.52
(ddd, J¼9.1, 7.0,1.5 Hz,1H); 8.58 (ddd, J¼7.3, 6.2,1.9 Hz,1H); 8.67 (ddt,
J¼8.2, 1.5, 0.5 Hz, 1H); 8.85 (d, J¼8.6 Hz, 1H); 8.90 (dq, J¼9.1, 0.9 Hz,
1H); 9.00 (ddd, J¼7.7, 1.9, 0.8 Hz,1H); 9.02 (td, J¼7.5, 1.4 Hz, 1H); 9.53
(dd, J¼8.6, 1.1 Hz, 1H), 9.54 (ddd, J¼6.2, 1.4, 0.6 Hz, 1H). 13C NMR
Rf [SiO2, Stoddart’s magic mixture]: 0.41. Mp 113–116 ꢀC. 1H NMR
(600 MHz, acetone-d6):
d¼2.56 (t, J¼2.7 Hz, 1H); 2.58–2.61 (m, 4H);
2.74 (t, J¼2.8 Hz,1H); 3.40 (td, J¼6.7, 2.8 Hz, 2H); 5.38 (m, 2H); 5.92 (t,
J¼6.7 Hz, 2H); 8.26 (ddd, J¼8.2, 7.0, 0.9 Hz, 1H); 8.52–8.55 (m, 1H);
8.53 (ddd, J¼9.0, 7.0,1.5 Hz,1H); 8.69 (ddt, J¼8.2,1.5, 0.5 Hz,1H); 8.89
(151 MHz, acetone-d6):
d¼16.28; 21.02; 28.95; 56.51; 60.24; 71.80;

3546
L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
(d, J¼8.6 Hz,1H); 8.95–8.98 (m, 2H); 8.96 (dq, J¼9.0, 0.9 Hz,1H); 9.54
(dt, J¼6.2, 1.1 Hz, 1H); 9.59 (dd, J¼8.6,1.1 Hz, 1H). 13C NMR (151 MHz,
1H); 3.33 (td, J¼6.6, 2.7, 2H); 5.45 (t, J¼6.6, 2H); 5.46 (t, J¼7.2 Hz
2H); 8.28 (ddd, J¼8.4, 7.0, 1.2 Hz, 1H); 8.41 (ddd, J¼8.3, 6.9, 1.2 Hz,
1H); 8.52–8.60 (m, 2H); 8.90 (broad d, J¼6.8 Hz, 1H); 8.98–9.06 (m,
3H); 9.17 (d, J¼6.8 Hz, 1H); 9.52–9.56 (m, 1H). 13C NMR (100 MHz,
acetone-d6): 16.75; 21.82; 30.92; 61.07; 62.44; 72.49; 76.11; 79.73;
83.69; 91.58; 98.64; 129.82; 129.86; 130.55; 131.54; 131.93; 134.98;
136.41; 136.47; 138.98; 139.00; 139.10; 139.47; 148.23; 149.76. IR
~
2229m; 3453m. MS (ESI) m/z: 499.0 [(MꢁOTf)þ] (100); 350.2 [(M-
2OTf)2þ]. HRMS (ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd:
499.1298, found: 499.1288.
acetone-d6):
d
¼15.93; 19.99; 30.00;55.26;61.50;72.00; 75.50;79.46;
82.84; 93.92; 94.89; 120.34; 128.14; 131.09; 131.58; 132.19; 132.36;
135.55; 135.85; 138.63; 139.49; 140.45; 147.05; 148.87; 149.09. IR
~
(KBr):
n
(cmꢁ1)1032s,1159s,1255vs;1617m;3085w. MS(ESI)m/z:499
[(MꢁOTf)þ] (76). HRMS(ESI)m/z:[(MꢁOTf)þ](C26H22F3N2O3S)calcd:
499.1298, found: 499.1294. Elem. Anal. Calcd for C27H22F6N2O6S2: C,
50.00; H, 3.42; N, 4.32. Found: C, 49.58; H, 3.38; N, 4.06.
(thin film):
n
(cmꢁ1) 1030s; 1051m; 1157m; 1226s; 1253s; 1688m;
4.13.13. 1-(Pent-3-ynyl)-2-((1-(pent-4-ynyl)pyridinium-2-yl)ethy-
nyl)quinolinium trifluoromethanesulfonate (30). Following the gen-
eral procedure for organic dication formation II and general workup
procedure III, two portions of neat pent-3-ynyl tri-
4.14. Synthesis of helquats
fluoromethanesulfonate (D) (each portion: 43 mL, 56.5 mg,
Helquats were synthesized by one of two general procedures
which was followed by one of three workup procedures.
0.26 mmol, 1 equiv) and a solution of organic monocation salt 24
(116.6 mg, 0.26 mmol, 1 equiv) in DCM (2 mL) gave pure organic
dication salt 30 as a light brown oil in 55% yield (95.0 mg, 0.14 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.41. 1H NMR (600 MHz,
4.15. Helquat formation, general procedure I (14–20, 31–36)
acetone-d6):
d
¼1.66 (t, J¼2.6 Hz, 3H); 2.57 (t, J¼2.7 Hz, 1H); 2.58–
Degassed DMF was added to a mixture of [Rh(PPh3)3Cl] (10–
12 mol %) and organic dication salt (1 equiv) under Ar. The solution
stirredbetween30 minand2 hat90–130 ꢀC, andwascooled to25 ꢀC.
2.62 (m, 4H); 3.30 (tq, J¼6.7, 2.6 Hz, 2H); 5.37 (m, 2H); 5.85 (t,
J¼6.7 Hz, 2H); 8.25 (ddd, J¼8.2, 7.0, 0.9 Hz, 1H); 8.51 (ddd, J¼9.1,
7.0, 1.5 Hz, 1H); 8.51–8.53 (m, 1H); 8.67 (ddt, J¼8.2, 1.5, 0.5 Hz, 1H);
8.89 (d, J¼8.7, 1H); 8.95 (dq, J¼9.1, 0.9 Hz, 1H); 8.95–8.98 (m, 2H);
9.53 (dt, J¼6.2, 1.0 Hz, 1H); 9.57 (dd, J¼8.7, 0.9 Hz, 1H). 13C NMR
4.16. Helquat formation, general procedure II (40, 43)
(151 MHz, acetone-d6):
d
¼3.17; 15.92; 20.48; 29.98; 55.77; 61.46;
A solution of organic dication salt in DMF was added to a Schlenk
flask containing [Rh(PPh3)3Cl] (6–8 mol %) prepared under Ar. The
reaction was stirred for 1 h at 100 ꢀC and cooled to 25 ꢀC.
71.97; 74.53; 82.44; 82.85; 93.93; 94.48; 120.37; 129.07; 131.05;
131.51; 132.08; 132.28; 135.50; 135.88; 138.39; 139.30; 140.41;
(cmꢁ1) 1030s, 1157s, 1261vs;
~
n
147.05; 148.66; 149.10. IR (KBr):
1618m; 3089w. MS (ESI) m/z: 513 [(MꢁOTf)þ] (81). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C27H24F3N2O3S) calcd: 513.1454, found: 513.1451.
4.17. Helquat formation, general workup procedure I (14, 15,
18, 19, 20, 40)
4.13.14. 2-(But-3-ynyl)-1-((1-(pent-4-ynyl)pyridinium-2-yl)ethynyl)-
isoquinolinium trifluoromethanesulfonate (39). Following the gen-
eral procedure for organic dication formation I with a reaction time
of 36 h and general workup procedure IV, neat pent-4-ynyl tri-
All volatiles were removed in vacuo from the reaction mixture. A
mixture of solvents (one of the following three mixtures was used:
ethyl acetate/acetone 2:1, ethyl acetate/diethyl ether 1:1, or pure
ethyl acetate) was added to the residue and this mixture, contained
in a RBF, was immersed in an ultrasonic bath and sonicated for 1 min
giving a fine suspension. The supernatant solution was separated
from the fine powder via centrifuge and then removed via pipette.
The wash was repeated (2ꢂ) and the product was transferred to
a vial and dried under vacuum (2 mbar) to give pure helquat.
fluoromethanesulfonate (C) (21.3
and a solution of organic monocation salt 38 (13.6 mg, 31.5
1 equiv) in DCM (1 mL) gave organic dication salt 39 as a light
yellow glass in 82% yield (16.8 mg, 25.9 mol).
mL, 27.2 mg, 0.126 mmol, 4 equiv)
mmol,
m
Rf [SiO2, Stoddart’s magic mixture]: 0.42. 1H NMR (400 MHz,
acetone-d6): 2.39 (t, J¼2.6 Hz, 1H); 2.48–2.63 (m, 4H); 2.74 (t, J¼2.7,
1H); 3.35 (td, J¼6.6, 2.7 Hz, 2H); 5.38 (t, J¼7.2 Hz, 2H); 5.54 (t,
J¼6.5 Hz 2H); 8.30 (ddd, J¼8.4, 7.0, 1.2 Hz, 1H); 8.43 (ddd, J¼8.3, 6.9,
1.1 Hz, 1H); 8.52 (ddd, J¼7.5, 6.2, 2.0 Hz, 1H); 8.57 (broad d,
J¼8.4 Hz, 1H); 8.91–9.01 (m, 3H); 9.06 (dq, J¼8.6, 0.9 Hz, 1H); 9.20
(d, J¼6.8 Hz, 1H); 9.51 (ddd, J¼6.1, 1.4, 0.6 Hz, 1H). 13C NMR
(100 MHz, acetone-d6): 16.62; 21.86; 61.23; 62.35; 72.53; 75.82;
80.00; 83.37; 91.17; 99.23; 129.47; 129.82; 130.65; 131.59; 131.76;
135.09; 136.62; 136.64; 139.22; 139.28; 139.55; 139.60; 147.72;
149.54; 1 carbon peak likely obscured by (CD3)2CO peak. IR (thin
~
4.18. Helquat formation, general workup procedure II
(16, 17, 43)
All volatiles were removed in vacuo from the reaction mixture.
Water and DCM were added to the resultant residue, and the
mixture was stirred vigorously until all material dissolved. The
aqueous layer was separated, washed with DCM (2ꢂ) and con-
centrated in vacuo to give pure helquat.
film):
n
(cmꢁ1) 1030s; 1053m; 1157m; 1225s; 1258s; 1692m;
2231m; 3489m. MS (ESI) m/z: 499.0 [(MꢁOTf)þ] (100); 396.0 (30);
350.2 [(M-2OTf)2þ] (20); 283.2 (40); 175.3 (45). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298, found: 499.1294.
4.19. Helquat formation, general workup procedure III
(31–36)
All volatiles were removed in vacuo from the reaction mixture.
Water and DCM were added to the resultant residue, and the
mixture was stirred vigorously until all material dissolved. The
aqueous layer was separated, washed with DCM (3ꢂ) and con-
centrated in vacuo. Diethyl ether (8 mL) was added to the oil and
this mixture, contained in a RBF, was immersed in an ultrasonic
bath and sonicated for 1 min giving a fine suspension. The super-
natant solution was separated from the fine powder via centrifuge
and then removed via decantation. This diethyl ether wash was
repeated (2ꢂ) and the product was transferred to a vial and dried
under vacuum (2 mbar) to give pure helquat.
4.13.15. 1-((1-(But-3-ynyl)pyridinium-2-yl)ethynyl)-2-(pent-4-ynyl)-
isoquinolinium trifluoromethanesulfonate (42). Following the gen-
eral procedure for organic dication formation I with a reaction time
of 36 h and general workup procedure IV, neat but-3-ynyl tri-
fluoromethanesulfonate (A) (31
and a solution of organic monocation salt 41 (22.5 mg, 50.4
1 equiv) in DCM (1.5 mL) gave organic dication salt 42 as a light
mL, 41.3 mg, 0.204 mmol, 4 equiv)
mmol,
yellow glass in 71% yield (23.2 mg, 35.8 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.45. 1H NMR (400 MHz,
acetone-d6): 2.46 (t, J¼2.6 Hz, 1H); 2.52–2.65 (m, 4H); 2.80 (t, J¼2.7,

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3547
4.19.1. Helquat 14.
24); 7.92 (ddt, J¼8.2,1.2, 0.6 Hz,1H, H-4); 8.16 (s, 1H, H-18); 8.25 (dd,
J¼6.7, 0.7 Hz, 1H, H-23); 8.29 (dd, J¼6.6, 0.8 Hz, 1H, H-3); 9.02 (d,
J¼6.7 Hz, 1H, H-22); 9.07 (d, J¼6.6 Hz, 1H, H-2). 13C NMR (151 MHz,
+
acetone-d6,):
d
¼14.31 (C-40); 23.27 (C-39); 25.29 (C-19); 28.37 (C-
12); 30.02, 30.05, 30.28, 30.29, 30.32 (C-33, C-34, C-35, C-36 and C-37
not necessarily in that order); 30.96 (C-32); 32.58 (C-38); 33.95 (C-
31); 55.80 (C-20); 55.99 (C-11); 125.34 (C-23); 125.63 (C-3); 126.23
(C-14); 126.55 (C-24); 126.62 (C-4); 126.97 (C-30); 127.10 (C-10);
128.29 (C-15); 128.43 (C-27); 128.47 (C-7); 132.15 (C-6); 132.18 (C-
26); 134.48 (C-18); 136.03 (C-5); 136.04 (C-25); 137.68 (C-2); 137.78
(C-22); 138.04 (C-9); 138.84 (C-29); 141.12 (C-16); 141.43 (C-13);
(cmꢁ1) 1030s,
~
148.11 (C-17); 150.89 (C-28); 151.05 (C-8). IR (KBr):
n
+
Following general procedure for helquat formation I with a re-
action time of 1 h and a reaction temperature of 110 ꢀC, and general
workup procedure I using ethyl acetate/acetone 2:1, [Rh(PPh3)3Cl]
1153s, 1261vs, 1277vs, 1626w, 3084w. MS (ESI) m/z: 675 [(MꢁOTf)þ]
(32), 526 (15), 263 [(M-2OTf)2þ] (100). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C39H42F3N2O3S) calcd: 675.2863, found: 675.2855.
(6.4 mg, 6.92 mmol, 10 mol %), organic dication salt 7 (46.2 mg,
0.066 mmol, 1 equiv), and DMF (7 mL) gave pure helquat 14 as
a white solid in 82% yield (38.0 mg, 0.054 mmol).
4.19.3. Helquat 16.
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 322–324 ꢀC. Rf [SiO2,
+
Stoddart’s magic mixture]: 0.32. 1H NMR (600 MHz, acetone-d6):
d¼2.80 (broad t, J¼0.6 Hz, 3H, H-31); 3.53 (dt, J¼16.5, 9.5 Hz, 1H, H-
12a); 3.68–3.71 (m, 2H, H-19); 3.86 (ddd, J¼16.5, 3.1, 2.1 Hz, 1H, H-
12b); 5.44–5.55 (m, 4H, H-11 & H-20); 7.65 (ddd, J¼8.7, 6.9,1.3 Hz,1H,
H-6); 7.66 (ddd, J¼8.6, 7.0, 1.2 Hz, 1H, H-26); 7.78 (dq, J¼8.7, 1.0 Hz,
1H, H-7); 7.78–7.82 (m, 2H, H-5 & H-25); 7.81 (dq, J¼8.6,1.0 Hz,1H, H-
27); 7.90–7.94 (m, 2H, H-4 & H-24); 8.13 (q, J¼0.9 Hz, 1H, H-18); 8.26
(dd, J¼6.7, 0.7 Hz, 1H, H-23); 8.29 (dd, J¼6.7, 0.8, 1H, H-3); 9.02 (d,
J¼6.7 Hz, 1H, H-22); 9.06 (d, J¼6.7 Hz, 1H, H-2). 13C NMR (151 MHz,
+
acetone-d6):
d¼19.87 (C-31); 25.49 (C-19); 28.31 (C-12); 55.71 (C-
Following general procedure for helquat formation I with a re-
action time of 2 h and a reaction temperature of 130 ꢀC, and general
20); 55.97 (C-11); 125.39 (C-23); 125.64 (C-3); 126.11 (C-14); 126.56
(C-7); 126.60 (C-27); 126.96 (C-10); 127.06 (C-30); 128.07 (C-15);
128.45 (C-4); 128.49 (C-24); 132.15 (C-26 & C-6); 135.19 (C-18);
136.06 (C-5 & C-25); 137.69 (C-22); 137.76 (C-2); 138.87 (C-9 & C-29);
141.42 (C-13); 141.97 (C-16); 143.80 (C-17); 150.87 (C-8); 150.96 (C-
(cmꢁ1) 1030s, 1155s, 1261vs, 1625w, 3080w. MS (ESI)
~
28). IR (KBr):
n
workup procedure II, [Rh(PPh3)3Cl] (1.2 mg, 1.30
organic dication salt 9 (7.3 mg, 9.60 mol,1 equiv), and DMF (1.5 mL)
gave helquat 16 as a yellow oil in 75% yield (5.5 mg, 7.23 mol).
Rf [SiO2, Stoddart’s magic mixture]: 0. 51. 1H NMR (600 MHz,
acetone-d6):
¼3.59 (ddd, J¼16.8, 3.2, 1.9 Hz, 1H, H-19a); 3.76–3.83
mmol, 13.5 mol %),
m
m
d
m/z: 549 [(MꢁOTf)þ] (100), 400 (59), 200 [(M-2OTf)2þ] (95). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C30H24F3N2O3S) calcd: 549.1454, found:
549.1450. Elem. Anal. Calcd for C31H24F6N2O6S2: C, 53.29; H, 3.46; N,
4.01. Found: C, 53.02; H, 3.53; N, 3.82.
(m, 3H, H-12 & H-19b); 5.40–5.52 (m, 2H, H-11); 5.46 (td, J¼13.9,
3.2 Hz, 1H, H-20a); 5.57–5.62 (m, 1H, H-20b); 7.63–7.75 (m, 7H, H-
6, H-26, H-32, H-33 & H-34); 7.82 (ddd, J¼8.2, 6.8, 1.1 Hz, 1H, H-25);
7.83–7.85 (m, 1H, H-5); 7.86 (dq, J¼8.7, 0.8 Hz, 1H, H-27); 7.88 (dq,
J¼8.7, 0.8 Hz,1H, H-7); 7.93–7.97 (m, 2H, H-4 & H-24); 8.25 (t, J¼0.8,
1H, H-18); 8.30 (dd, J¼6.9, 0.8 Hz, 1H, H-23); 8.33 (dd, J¼6.7, 0.7 Hz,
1H, H-3); 9.07 (d, J¼6.9 Hz, 1H, H-22); 9.08 (d, J¼6.7 Hz, 1H, H-2).
4.19.2. Helquat 15.
13C NMR (151 MHz, acetone-d6):
d
¼27.49 (C-19); 28.52 (C-12);
+
56.10 (C-20); 56.16 (C-11); 125.65 (C-23); 126.43 (C-24); 126.64 (C-
4); 127.13 (C-14); 127.18 (C-30); 127.56 (C-10); 128.49 (C-27);
128.56 (C-7); 129.03 (C-15); 129.85 (C-33); 129.91 (C-3); 130.01 (C-
34); 130.22 (C-32); 132.22 (C-26); 132.38 (C-6); 134.68 (C-18);
136.14 (C-25); 136.15 (C-5); 137.71 (C-22); 137.94 (C-2); 138.63 (C-
31); 138.89 (C-29); 138.90 (C-9); 140.30 (C-16); 141.85 (C-13);
(cmꢁ1) 1030s,
~
146.88 (C-17); 150.79 (C-28); 151.11 (C-8). IR (KBr):
n
+
1155s,1262vs,1275vs,1626w, 3085w. MS (ESI) m/z: 611 [(MꢁOTf)þ]
(8), 461 (21), 231 [(M-2OTf)2þ] (100). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C35H26F3N2O3S) calcd: 611.1616, found: 611.1620.
Following general procedure for helquat formation I with a re-
action time of 2 h and a reaction temperature of 110 ꢀC, and general
workup procedure
[Rh(PPh3)3Cl] (2.5 mg, 2.70
I
using ethyl acetate/diethyl ether 2:1,
mol, 10 mol %), organic dication salt 8
4.19.4. Helquat 17.
m
(21.1 mg, 0.026 mmol, 1 equiv), and DMF (4 mL) gave pure helquat
15 as a light brown sticky solid in 69% yield (14.5 mg, 0.018 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.67. 1H NMR (600 MHz, ac-
etone-d6):
d¼0.91 (t, J¼7.2 Hz, 3H, H-40); 1.30–1.42 (m,10H, H-35, H-
36, H-37, H-38 & H-39); 1.44–1.50 (m, 2H, H-34); 1.57–1.63 (m, 2H, H-
33); 1.83–1.91 (m, 2H, H-32); 3.08–3.20 (m, 2H, H-31); 3.56 (ddd,
J¼16.9, 11.8, 7.9 Hz, 1H, H-19a); 3.70–3.74 (m, 2H, H-12); 3.92 (dt,
J¼16.9, 2.6 Hz, 1H, H-19b); 5.43–5.55 (m, 4H, H-11 & H-20); 7.655
(ddd, J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 7.66 (ddd, J¼8.5, 7.1, 1.2 Hz, 1H, H-
26); 7.77 (dq, J¼8.7, 0.9 Hz, 1H, H-7); 7.78–7.81 (m, 2H, H-5 & H-25);
7.81 (dq, J¼8.5, 0.9 Hz, 1H, H-27); 7.91 (ddt, J¼8.2, 1.2, 0.6 Hz, 1H, H-

3548
L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
Following general procedure for helquat formation I with a re-
action time of 1 h and a reaction temperature of 110 ꢀC, and general
workup procedure II, [Rh(PPh3)3Cl] (2.2 mg, 2.39 mol, 10 mol %),
organic dication salt 10 (17 mg, 23.85 mol, 1 equiv), and DMF
136.74 (C-19); 136.80 (C-26); 137.51 (C-23); 138.19 (C-2); 138.45 (C-
30); 138.64 (C-9); 138.67 (C-32); 139.17 (C-17); 141.51 (C-14);
~
m
146.70 (C-18); 151.36 (C-29); 155.69 (C-8). IR (KBr):
n
(cmꢁ1) 1030s,
m
1261vs, 1277vs, 1625w, 3083w. MS (ESI) m/z: 625 [(MꢁOTf)þ] (22),
475 (12), 238 [(M-2OTf)2þ] (100). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C36H28F3N2O3S) calcd: 625.1767, found: 625.1777.
(3 mL) gave helquat 17 as a yellow glass in 96% yield (16.4 mg,
23.01 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.34. 1H NMR (600 MHz,
acetone-d6):
d¼2.09–2.12 (m, 1H, H-13a); 2.23 (ddd, J¼14.5, 12.5,
4.19.6. Helquat 19.
7.6, 1H, H-14a); 2.32–2.40 (m, 2H, H-13b & H-12a); 2.72–2.80 (m,
1H, H-12b); 3.26 (dd, J¼14.5, 7.6 Hz, 1H, H-14b); 3.69 (ddd, J¼15.9,
3.4, 2.1 Hz, 1H, H-21a); 3.77 (ddd, J¼15.9, 13.8, 5.2 Hz, 1H, H-21b);
5.30 (td, J¼14.1, 3.4 Hz, 1H, H-22a); 5.35 (ddd, J¼14.4, 5.2, 2.1, 1H, H-
22b); 5.54 (broad dd, J¼13.5, 9.5 Hz, 1H, H-11a); 5.65 (broad dd,
J¼13.5, 6.1, 1H, H-11b); 7.40 (dq, J¼8.7, 0.9 Hz, 1H, H-7); 7.74 (ddd,
J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 7.87–7.94 (m, 4H, H-26, H-27, H-28 & H-
29); 7.97 (ddd, J¼8.2, 6.9, 1.1 Hz,1H, H-5); 8.08 (dt, J¼8.2, 0.9 Hz,1H,
H-4); 8.20 (d, J¼6.7 Hz, 1H, H-25); 8.27 (d, J¼8.0 Hz, 1H, H-20); 8.29
(dd, J¼8.0, 0.6 Hz, 1H, H-19); 8.46 (dd, J¼6.8, 0.6 Hz, 1H, H-3); 8.92
(broad d, J¼6.6 Hz, 1H, H-24); 9.15 (d, J¼6.8 Hz, 1H, H-2). 13C NMR
+
+
Following general procedure for helquat formation I with a re-
action time of 1 h and a reaction temperature of 110 ꢀC, and general
workup procedure I using ethyl acetate/acetone 2:1, [Rh(PPh3)3Cl]
(151 MHz, acetone-d6):
d
¼26.64 (C-13); 28.68 (C-12); 28.95 (C-21);
32.77 (C-14); 55.80 (C-22); 60.33 (C-11); 125.41 (C-25); 126.77 (C-
29); 127.08 (C-32); 127.64 (C-10); 128.04 (C-26); 128.24 (C-3);
128.44 (C-7); 128.73 (C-4); 129.25 (C-17); 129.28 (C-16); 131.23 (C-
28); 133.51 (C-6); 133.99 (C-19); 136.52 (C-27); 137.25 (C-5); 137.58
(C-24); 137.82 (C-20); 137.88 (C-2); 138.03 (C-31); 138.51 (C-9);
140.96 (C-18); 146.90 (C-15); 151.54 (C-30); 156.44 (C-8). IR (KBr):
~
(6.3 mg, 6.81 mmol, 10 mol %), organic dication salt 12 (46.4 mg,
0.066 mmol, 1 equiv), and DMF (7 mL) gave pure helquat 19 as
a white solid in 86% yield (39.7 mg, 0.057 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.33. Mp 272–274 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d
¼2.79 (ddd, J¼13.8, 12.5, 7.9 Hz, 1H,
n
(cmꢁ1) 1030s, 1262vs, 1274vs, 1627w, 3080w. MS (ESI) m/z: 563
H-13a); 2.84–2.91 (m, 1H, H-12a); 3.01–3.09 (m, 1H, H-12b); 3.30
(ddd, J¼13.8, 4.5, 1.0 Hz, 1H, H-13b); 3.72 (ddd, J¼16.1, 3.9, 2.2 Hz,
1H, H-20a); 3.78 (dddt, J¼16.1, 12.5, 6.1, 1.0 Hz, 1H, H-20b); 5.37
(broad ddd, J¼14.5, 12.5, 3.9 Hz, 1H, H-21a); 5.40 (dddd, J¼14.5, 6.1,
2.2, 0.7 Hz, 1H, H-21b); 5.51 (ddd, J¼13.7, 12.4, 5.2 Hz, 1H, H-11a);
5.54 (ddd, J¼13.7, 7.3, 1.5 Hz, 1H, H-11b); 7.50 (dq, J¼8.7, 0.9 Hz, 1H,
H-7); 7.69 (ddd, J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 7.76 (ddd, J¼8.6, 6.9,
1.3 Hz, 1H, H-27); 7.84 (ddd, J¼8.0, 6.9, 1.2 Hz, 1H, H-26); 7.89–7.93
(m, 3H, H-5, H-25 & H-28); 8.03 (ddt, J¼8.2, 1.2, 0.5 Hz, 1H, H-4);
8.20 (d, J¼7.8 Hz, 1H, H-19); 8.24 (broad dd, J¼6.6, 0.7 Hz, 1H, H-
24); 8.26 (dd, J¼7.8, 1.1 Hz, 1H, H-18); 8.43 (dd, J¼6.7, 1.0 Hz, 1H, H-
3); 8.98 (dt, J¼6.6, 0.8 Hz, 1H, H-23); 9.13 (d, J¼6.7 Hz, 1H, H-2). 13C
[(MꢁOTf)þ] (49), 413 (100). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C31H26F3N2O3S) calcd: 563.1611, found: 563.1621.
4.19.5. Helquat 18.
+
NMR (151 MHz, acetone-d6):
d
¼28.81 (C-20); 30.30 (C-13); 33.19
+
(C-12); 55.90 (C-21); 59.43 (C-11); 125.62 (C-24); 125.82 (C-28);
127.28 (C-31); 127.50 (C-7); 127.63 (C-3); 127.90 (C-10); 128.13 (C-
25); 128.71 (C-4); 129.22 (C-15); 129.62 (C-16); 131.68 (C-27);
133.07 (C-6); 133.99 (C-18); 136.22 (C-19); 136.29 (C-26); 136.79
(C-5); 137.77 (C-23); 138.23 (C-2); 138.52 (C-30); 138.69 (C-9);
141.32 (C-17); 141.79 (C-14); 150.93 (C-29); 155.55 (C-8). IR (KBr):
~
Following general procedure for helquat formation I with a re-
action time of 1.5 h and a reaction temperature of 110 ꢀC, and
general workup procedure I using ethyl acetate/acetone 2:1,
[Rh(PPh3)3Cl] (2.9 mg, 3.13
mmol, 10 mol %), organic dication salt 11
n
(cmꢁ1) 1030s, 1154s, 1263vs, 1625m, 3076w. MS (ESI) m/z: 549
(24.8 mg, 0.0320 mmol, 1 equiv), and DMF (4 mL) gave pure hel-
quat 18 as a white solid in 54% yield (13.3 mg, 0.017 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.56. Mp 242–243 ꢀC. 1H
[(MꢁOTf)þ] (100), 491 (24), 400 (11), 200 [(M-2OTf)2þ] (47). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C30H24F3N2O3S) calcd: 549.1454, found:
549.1449. Elem. Anal. Calcd for C31H26F6N2O6S2: C, 53.29; H, 3.46;
N, 4.01. Found: C, 53.10; H, 3.59; N, 3.77.
NMR (600 MHz, acetone-d6):
d¼2.84–2.92 (m, 2H, H-13a & H-12a);
3.03–3.10 (m, 1H, H-12b); 3.37–3.42 (m, 1H, H-13b); 3.54 (ddd,
J¼16.2, 13.2, 1.9 Hz, 1H, H-20a); 3.82 (ddd, J¼16.2, 13.7, 5.4 Hz, 1H,
H-20b); 5.27 (td, J¼14.0, 3.2 Hz, 1H, H-21a); 5.32 (broad ddd,
J¼14.6, 5.4, 1.9 Hz, 1H, H-21b); 5.54–5.56 (m, 2H, H-11); 7.61 (dq,
J¼8.7, 0.9 Hz, 1H, H-7); 7.63–7.66 (m, 1H, H-35); 7.68–7.72 (m, 2H,
H-34); 7.72 (ddd, J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 7.76–7.78 (m, 2H, H-
33); 7.80 (ddd, J¼8.5, 6.9, 1.3 Hz, 1H, H-27); 7.87 (ddd, J¼8.1, 6.9,
1.2 Hz, 1H, H-5); 7.91–7.96 (m, 2H, H-4 & H-26); 7.98 (dq, J¼8.5,
0.9 Hz, 1H, H-28); 8.05 (dt, J¼8.2, 1.0 Hz, 1H, H-25); 8.25 (dd, J¼6.7,
0.7 Hz, 1H, H-24); 8.27 (s, 1H, H-19); 8.42 (dd, J¼6.8, 0.9 Hz, 1H, H-
3); 8.98 (broad d, J¼6.8 Hz, 1H, H-23); 9.12 (d, J¼6.8 Hz, 1H, H-2).
4.19.7. Helquat 20.
+
+
13C NMR (151 MHz, acetone-d6):
d¼27.62 (C-20); 29.88 (C-13);
33.14 (C-12); 55.82 (C-21); 59.51 (C-11); 125.72 (C-24); 126.11 (C-
28); 127.41 (C-31); 127.57 (C-3 & C-7); 128.11 (C-10); 128.20 (C-4);
128.72 (C-25); 128.83 (C-15); 129.85 (C-34); 129.92 (C-35); 130.16
(C-16); 130.34 (C-33); 131.83 (C-27); 133.08 (C-6); 136.33 (C-5);
Following general procedure for helquat formation I with a re-
action time of 1 h and a reaction temperature of 110 ꢀC, and general
workup procedure I using ethyl acetate/acetone 2:1, [Rh(PPh3)3Cl]
(5.9 mg, 6.38 mmol, 10 mol %), organic dication 13 (44.0 mg,

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3549
0.062 mmol, 1 equiv), and DMF (7 mL) gave pure helquat 20 as
4.19.9. Helquat 32.
a white solid in 74% yield (32.4 mg, 0.046 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.39. Mp 251–253 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d
¼2.77 (ddd, J¼13.9, 12.4, 8.0 Hz, 1H,
H-13a); 2.81 (s, 3H, H-32); 2.83–2.92 (m, 1H, H-12a); 3.00–3.08 (m,
1H, H-12b); 3.24 (dd, J¼13.9, 6.6 Hz, 1H, H-13b); 3.56 (ddd, J¼16.3,
14.1, 4.9 Hz, 1H, H-20a); 3.85 (ddd, J¼16.3, 3.2, 1.8 Hz, 1H, H-20b);
5.32 (td, J¼14.3, 3.2 Hz, 1H, H-21a); 5.38 (ddd, J¼14.5, 4.9, 1.8 Hz,
1H, H-21b); 5.49–5.52 (m, 2H, H-11); 7.52 (dq, J¼8.7, 0.9 Hz, 1H, H-
7); 7.70 (ddd, J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 7.75 (ddd, J¼8.5, 6.9,
1.3 Hz, 1H, H-27); 7.83 (ddd, J¼8.2, 6.9, 1.1 Hz, 1H, H-26); 7.88–7.91
(m, 2H, H-25 & H-28); 7.90 (ddd, J¼8.2, 6.9, 1.1 Hz, 1H, H-5); 8.02
(ddt, J¼8.2,1.2, 0.5 Hz,1H, H-4); 8.09 (s,1H, H-19); 8.21 (d, J¼6.6 Hz,
1H, H-24); 8.38 (broad d, J¼6.8 Hz, 1H, H-3); 8.97 (broad d,
J¼6.6 Hz, 1H, H-23); 9.09 (d, J¼6.8 Hz, 1H, H-2). 13C NMR (151 MHz,
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and
general workup procedure III, [Rh(PPh3)3Cl] (6.5 mg, 7.02 mmol,
10 mol %), organic dication salt 26 (45.8 mg, 0.071 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 32 as a brown powder in 66%
yield (31.7 mg, 0.047 mmol).
acetone-d6):
d¼19.82 (C-32); 25.44 (C-20); 30.31 (C-13); 33.25 (C-
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 118–122 ꢀC. 1H
12); 55.45 (C-21); 59.43 (C-11); 125.46 (C-24); 126.04 (C-28);
127.34 (C-3 & C-15); 127.36 (C-31); 127.65 (C-7); 128.05 (C-10);
128.11 (C-25); 128.65 (C-4); 129.17 (C-16); 131.60 (C-27); 132.99 (C-
6); 136.21 (C-26); 136.70 (C-5); 137.52 (C-23); 137.61 (C-19); 138.10
(C-2); 138.42 (C-30); 138.62 (C-9); 140.38 (C-17); 141.13 (C-14);
NMR (600 MHz, acetone-d6):
d¼2.63 (td, J¼14.2, 6.5 Hz, 1H, H-13a),
2.72–2.79 (m, 1H, H-12a); 3.04–3.11 (m, 1H, H-12b); 3.20 (dd,
J¼14.4, 5.9 Hz, 1H, H-13b); 3.62–3.70 (m, 2H, H-20); 5.14 (ddd,
J¼14.7, 13.6, 5.5 Hz, 1H, H-11a); 5.19 (td, J¼13.1, 6.3 Hz, 1H, H-21a);
5.31 (ddd, J¼13.2, 4.4, 2.2 Hz, 1H, H-21b); 6.00 (dd, J¼14.7, 5.9 Hz,
1H, H-11b); 7.93 (dd, J¼8.2, 1.4 Hz, 1H, H-26); 7.94 (d, J¼7.7 Hz, 1H,
H-18); 8.02 (broad d, J¼7.7 Hz, 1H, H-19); 8.08 (ddd, J¼7.7, 6.1,
0.6 Hz, 1H, H-24); 8.17 (ddd, J¼8.1, 7.0, 0.8 Hz, 1H, H-6); 8.23 (dddd,
J¼8.2, 7.7, 1.6, 0.7 Hz, 1H, H-25); 8.25 (d, J¼8.7 Hz, 1H, H-3); 8.45
(ddd, J¼9.0, 7.0,1.5 Hz, H, H-7); 8.57 (dd, J¼8.1, 1.5 Hz,1H, H-5); 8.99
(broad d, J¼9.0 Hz, 1H, H-8); 9.12 (dd, J¼8.7, 1.0 Hz, 1H, H-4); 9.28
(ddd, J¼6.1, 1.6, 0.6 Hz, 1H, H-23). 13C NMR (151 MHz, acetone-d6):
142.96 (C-18); 151.29 (C-29); 155.86 (C-8). IR (KBr): (cmꢁ1) 1030s,
~
n
1262vs, 1275vs, 1626m, 3085w. MS (ESI) m/z: 563 [(MꢁOTf)þ] (87),
413 (53), 288 (14), 207 [(M-2OTf)2þ] (100). HRMS (ESI) m/z:
[(MꢁOTf)þ] (C31H26F3N2O3S) calcd: 563.1611, found: 563.1608.
Elem. Anal. Calcd for C32H26F6N2O6S2: C, 53.93; H, 3.68; N, 3.93.
Found: C, 53.67; H, 3.88; N, 3.72.
4.19.8. Helquat 31.
d
¼28.15 (C-20); 30.31 (C-13); 31.88 (C-12); 53.42 (C-11); 56.24 (C-
7
-
2TfO
21); 120.01 (C-8); 127.12 (C-3); 127.42 (C-16 & C-24); 127.64 (C-15);
130.75 (C-9); 131.20 (C-26); 131.25 (C-6); 131.81 (C-5); 133.69 (C-
18); 135.00 (C-19); 137.30 (C-7); 140.37 (C-14); 140.51 (C-10);
140.68 (C-17); 145.91 (C-25); 147.30 (C-27); 147.59 (C-4); 147.66 (C-
(cmꢁ1) 1030s, 1152s, 1261vs; 3086w.
~
23); 157.54 (C-2). IR (KBr):
n
6
8
11
14
15
10
5
N+
12
13
9
27
4
2
18
17
3
25
26
MS (ESI) m/z: 499 [(MꢁOTf)þ] (100). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C26H22F3N2O3S) calcd: 499.1298, found: 499.1294. Elem. Anal.
Calcd for C27H22F6N2O6S2$(H2O)1.5: C, 48.00; H, 3.73; N, 4.15. Found:
C, 47.57; H, 3.52; N, 4.15.
24
23
16
19
N+
22
20
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and
general workup procedure III, [Rh(PPh3)3Cl] (5.3 mg, 5.72 mmol,
4.19.10. Helquat 33.
10 mol %), organic dication salt 25 (37.5 mg, 0.057 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 31 as a brown powder in 79%
yield (29.7 mg, 0.045 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 138–141 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d
¼2.66 (d, J¼0.9 Hz, 3H, H-27); 3.41
(ddd, J¼17.8, 13.7, 4.9 Hz, 1H, H-12a); 3.56–3.62 (m, 2H, H-19); 3.78
(ddd, J¼17.8, 3.8, 1.7 Hz, 1H, H-12b); 5.02 (ddd, J¼15.0, 13.7, 3.8 Hz,
1H, H-11a); 5.22 (ddd, J¼13.4, 11.0, 8.1 Hz, 1H, H-20a); 5.31 (ddd,
J¼13.4, 4.2, 2.4 Hz, 1H, H-20b), 6.18 (ddd, J¼15.0, 4.9, 1.7 Hz, 1H, H-
11b); 7.90 (q, J¼0.9 Hz, 1H, H-17); 8.09 (m, 1H, H-23); 8.10 (ddd,
J¼8.1, 7.0, 1.0 Hz, 1H, H-6); 8.28–8.30 (m, 2H, H-24 & H-25); 8.39
(ddd, J¼8.9, 7.0, 1.7 Hz, 1H, H-7); 8.42 (d, J¼8.8 Hz, 1H, H-3); 8.47
(dd, J¼8.1, 1.7 Hz,1H, H-5); 8.90–8.93 (m, 2H, H-4 & H-8); 9.25 (ddd,
J¼6.2, 1.5, 0.7 Hz, 1H, H-22). 13C NMR (151 MHz, acetone-d6):
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and
general workup procedure III, [Rh(PPh3)3Cl] (6.1 mg, 6.59 mmol,
10 mol %), organic dication salt 27 (42.9 mg, 0.066 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 33 as a brown powder in 76%
yield (33.1 mg, 0.050 mmol).
d
¼19.43 (C-27); 25.49 (C-12); 28.00 (C-19); 48.45 (C-11); 56.03 (C-
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 135–139 ꢀC. 1H
20); 119.93 (C-8); 126.75 (C-3); 127.21 (C-23); 128.10 (C-15); 128.77
(C-14); 130.03 (C-9); 130.76 (C-6); 131.29 (C-25); 131.36 (C-5);
135.11 (C-17); 136.57 (C-7); 140.94 (C-10); 141.24 (C-16); 141.72 (C-
13); 142.59 (C-18); 145.67 (C-24); 145.89 (C-4); 147.18 (C-22);
~
NMR (600 MHz, acetone-d6):
d¼2.66 (d, J¼0.8 Hz, 3H, H-27); 3.40
(ddd, J¼17.5, 13.3, 4.8 Hz, 1H, H-19a); 3.60 (ddd, J¼17.5, 15.3, 4.8 Hz,
1H, H-12a); 3.67 (ddd, J¼17.5, 4.2, 1.8 Hz, 1H, H-12b); 3.70 (ddd,
J¼17.5, 3.8, 1.6 Hz, 1H, H-19b); 5.03 (td, J¼14.3, 4.2 Hz, 1H, H-11a);
5.20 (td, J¼13.3, 3.8 Hz, 1H, H-20a); 5.36 (ddd, J¼13.3, 4.8, 1.6 Hz,
1H, H-20b); 6.14 (ddd, J¼13.5, 4.8, 1.8 Hz, 1H, H-11b); 7.90 (q,
J¼0.8 Hz,1H, H-18); 8.08 (ddd, J¼8.1, 7.0, 0.8 Hz,1H, H-6); 8.13 (ddd,
J¼7.2, 6.1, 1.8 Hz, 1H, H-23); 8.29 (ddd, J¼8.3, 1.8, 0.8 Hz, 1H, H-25);
8.32 (ddd, J¼8.3, 7.2, 1.4 Hz, 1H, H-24); 8.37 (ddd, J¼9.0, 7.0, 1.6 Hz,
147.82 (C-26); 151.55 (C-2). IR (KBr):
n
(cmꢁ1) 1030s, 1154s, 1260vs;
1602m; 3085w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (100). HRMS (ESI)
m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298, found:
499.1294. Elem. Anal. Calcd for C27H22F6N2O6S2$(H2O): C, 48.65; H,
3.63; N, 4.20. Found: C, 48.31; H, 3.49; N, 4.14.

3550
L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
1H, H-7); 8.40 (d, J¼8.8 Hz, 1H, H-3); 8.47 (ddt, J¼8.1, 1.6, 0.6 Hz, 1H,
H-5); 8.89 (dq, J¼9.0, 0.8 Hz,1H, H-8); 8.91 (dd, J¼8.8, 0.9 Hz,1H, H-
4); 9.29 (ddq, J¼7.2, 1.4, 0.7 Hz, 1H, H-22). 13C NMR (151 MHz, ac-
general workup procedure III, [Rh(PPh3)3Cl] (6.3 mg, 6.81 mmol,
10 mol %), organic dication salt 29 (44.2 mg, 0.068 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 35 as a brown powder in 80%
yield (35.4 mg, 0.054 mmol).
etone-d6):
d
¼19.73 (C-27); 25.52 (C-19); 27.78 (C-12); 48.68 (C-11);
55.60 (C-20); 119.82 (C-8); 126.55 (C-3); 126.57 (C-14); 127.53 (C-
23); 128.32 (C-15); 129.90 (C-9); 130.64 (C-6); 131.39 (C-5); 131.63
(C-25); 133.89 (C-18); 136.52 (C-7); 140.61 (C-10); 141.36 (C-13);
141.66 (C-16); 143.97 (C-17); 145.69 (C-24); 145.82 (C-4); 147.03 (C-
(cmꢁ1) 1030s, 1154s,
~
22); 147.92 (C-26); 151.41 (C-2). IR (KBr):
n
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 256–262 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d¼2.59–2.71 (m, 2H, H-19a & H-20a);
3.18–3.22 (m, 1H, H-19b); 2.93–3.00 (m, 1H, H-20b); 3.65 (broad
ddd, J¼14.7, 13.5, 4.2 Hz, 1H, H-12a); 3.72 (ddd, J¼17.0, 4.2, 2.1 Hz,
1H, H-12b); 5.01 (dddd, J¼14.7, 13.5, 4.2, 0.7 Hz, 1H, H-11a); 5.09
(td, J¼13.6, 5.7 Hz, 1H, H-21a); 5.27 (dd, J¼13.8, 6.6 Hz, 1H, H-21b);
6.08 (dddt, J¼13.5, 4.8, 2.1, 0.7, 1H, H-11b); 7.77 (d, J¼8.8 Hz, 1H, H-
3); 7.97 (d, J¼7.7 Hz, 1H, H-17); 8.04 (dd, J¼7.0, 1.0 Hz, 1H, H-18);
8.07 (ddd, J¼8.1, 7.0, 0.8 Hz, 1H, H-6); 8.15 (dd, J¼8.0, 1.8 Hz, 1H, H-
26); 8.31 (ddd, J¼7.7, 6.2, 1.8 Hz, 1H, H-24); 8.37 (ddd, J¼9.0, 7.0,
1.5 Hz, 1H, H-7); 8.41 (dd, J¼8.1, 1.5 Hz, 1H, H-5); 8.48 (td, J¼8.7,
1.5 Hz, 1H, H-25); 8.85 (broad d, J¼8.8 Hz, 1H, H-4); 8.87 (m, 1H, H-
8); 9.49 (ddd, J¼6.2, 1.5, 0.6 Hz, 1H, H-23). 13C NMR (151 MHz, ac-
1260vs; 1600m; 3090w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (62). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298, found:
499.1298. Elem. Anal. Calcd for C27H22F6N2O6S2$(H2O): C, 48.65; H,
3.63; N, 4.20. Found: C, 48.70; H, 3.58; N, 4.16.
4.19.11. Helquat 34.
etone-d6):
d
¼27.92 (C-12); 30.31 (C-19); 32.27 (C-20); 49.04 (C-11);
59.41 (C-21); 119.80 (C-8); 126.06 (C-3); 129.06 (C-24); 129.17 (C-
14); 129.76 (C-9); 130.81 (C-6); 131.19 (C-15), 131.38 (C-5); 132.74
(C-18); 132.84 (C-26); 135.62 (C-17); 136.75 (C-7); 140.52 (C-13);
140.80 (C-10); 140.81 (C-16); 146.03 (C-4); 146.74 (C-25); 148.18 (C-
~
23); 150.86 (C-2); 153.32 (C-27). IR (KBr):
n
(cmꢁ1) 1030s, 1162s,
1266vs; 1602m; 3081w. MS (ESI) m/z: 499 [(MꢁOTf)þ] (100). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298, found:
499.1294. Elem. Anal. Calcd for C27H22F6N2O6S2$(H2O)0.5: C, 49.32;
H, 3.53; N, 4.26. Found: C, 49.07; H, 3.37; N, 4.12.
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and
general workup procedure III, [Rh(PPh3)3Cl] (7.7 mg, 8.32 mmol,
10 mol %), organic dication salt 28 (55.4 mg, 0.083 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 34 as a brown powder in 65%
yield (37.0 mg, 0.054 mmol).
4.19.13. Helquat 36.
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 131–134 ꢀC. 1H
NMR (600 MHz, acetone-d6):
d¼2.61–2.67 (m, 1H, H-13a); 2.66 (t,
J¼0.6 Hz, 3H, H-28); 2.71–2.79 (m, 1H, H-12a); 3.05–3.12 (m, 1H, H-
12b); 3.15 (dd, J¼14.7, 5.9 Hz, 1H, H-13b); 3.44 (ddd, J¼17.2, 15.2,
4.8 Hz, 1H, H-20a); 3.72 (ddd, J¼17.2, 3.8, 1.8 Hz, 1H, H-20b); 5.13
(ddd, J¼14.7, 13.6, 5.5 Hz, 1H, H-11a); 5.15 (dddt, J¼15.2, 13.3, 3.8,
0.9 Hz, 1H, H-21a); 5.32 (ddd, J¼13.3, 4.8, 1.8 Hz, 1H, H-21b); 5.98
(dd, J¼14.7, 5.8 Hz,1H, H-11b); 7.84 (q, J¼0.6 Hz,1H, H-19); 7.89 (dd,
J¼8.2, 1.3 Hz, 1H, H-26); 8.07 (ddd, J¼7.6, 6.1, 1.3 Hz, 1H, H-24); 8.16
(ddd, J¼8.0, 7.0, 0.9 Hz, 1H, H-6); 8.21 (dddd, J¼8.2, 7.6, 1.5, 0.6 Hz,
1H, H-25); 8.22 (d, J¼8.6 Hz, 1H, H-3); 8.43 (ddd, J¼8.9, 7.0, 1.5 Hz,
1H, H-7); 8.55 (dd, J¼8.0, 1.5 Hz, 1H, H-5); 8.96 (m, 1H, H-8); 9.08
(dd, J¼8.6, 0.9 Hz, 1H, H-4); 9.27 (ddd, J¼6.1, 1.5, 0.6 Hz, 1H, H-23).
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and
general workup procedure III, [Rh(PPh3)3Cl] (7.8 mg, 8.43 mmol,
10 mol %), organic dication salt 30 (56.1 mg, 0.084 mmol, 1 equiv),
and DMF (2 mL) gave pure helquat 36 as a brown powder in 69%
yield (39.2 mg, 0.058 mmol).
13C NMR (151 MHz, acetone-d6):
d¼19.55 (C-28); 25.27 (C-20);
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 230–234 ꢀC.1H NMR
30.31 (C-13); 31.97 (C-12); 53.52 (C-11); 55.74 (C-21); 119.98 (C-8);
127.25 (C-24); 127.40 (C-3); 127.69 (C-16); 129.61 (C-15); 130.57 (C-
9); 131.13 (C-6); 131.35 (C-26); 131.77 (C-5); 136.32 (C-19); 137.19
(C-7); 139.48 (C-17); 140.22 (C-14); 140.49 (C-10); 142.86 (C-18);
145.75 (C-25); 147.31 (C-4); 147.35 (C-23); 147.64 (C-27); 157.87 (C-
(cmꢁ1) 1030s, 1152s, 1261vs; 1599m; 3086w. MS (ESI)
~
2). IR (KBr):
n
(600 MHz, acetone-d6):
d¼2.60–2.71 (m, 3H, H-19a & H-20); 2.67 (t,
J¼0.7 Hz, 3H, H-28); 3.13–3.17 (m,1H, H-19b); 3.46 (ddd, J¼17.4,15.1,
5.1 Hz, 1H, H-12a); 3.79 (ddd, J¼17.4, 3.8, 1.9 Hz, 1H, H-12b); 4.98
(dddd, J¼15.1,13.7, 3.8, 0.8,1H, H-11a); 5.08 (td, J¼13.6, 5.9 Hz,1H, H-
21a); 5.26 (dd, J¼13.7, 6.5 Hz, 1H, H-21b); 6.10 (ddd, J¼13.7, 5.1,
1.9 Hz, 1H, H-11b); 7.86 (q, J¼0.7 Hz, 1H, H-17); 7.74 (d, J¼8.8 Hz, 1H,
H-3); 8.07 (ddd, J¼8.1, 7.0, 0.8 Hz,1H, H-6); 8.13 (dd, J¼8.0,1.7 Hz,1H,
H-26); 8.28 (ddd, J¼7.8, 6.2, 1.7 Hz, 1H, H-24); 8.37 (ddd, J¼9.0, 7.0,
1.5 Hz, 1H, H-7); 8.40 (dd, J¼8.1, 1.5 Hz, 1H, H-5); 8.45 (td, J¼7.9,
1.5 Hz,1H, H-25); 8.82 (broad d, J¼8.8 Hz,1H, H-4); 8.88 (m,1H, H-8);
9.46 (ddd, J¼6.2, 1.5, 0.6 Hz, 1H, H-23). 13C NMR (151 MHz, acetone-
m/z: 513 [(MꢁOTf)þ] (68). HRMS (ESI) m/z: [(MꢁOTf)þ]
(C27H24F3N2O3S) calcd: 513.1454, found: 513.1450. Elem. Anal. Calcd
for C28H24F6N2O6S2$(H2O)1.5: C, 48.77; H, 3.95; N, 4.06. Found: C,
48.41; H, 3.69; N, 4.06.
4.19.12. Helquat 35.
d6):
d
¼19.30 (C-28); 25.23 (C-19); 29.34 (C-12); 32.35 (C-20); 48.65
(C-11); 59.45 (C-21); 119.80 (C-8); 126.23 (C-3); 128.75 (C-24);
128.94 (C-14); 129.21 (C-15); 129.65 (C-9); 130.76 (C-6); 131.34 (C-
5); 132.99 (C-26); 136.67 (C-7); 136.89 (C-17); 139.61 (C-13); 140.30
(C-16); 140.64 (C-10); 141.84 (C-18); 145.82 (C-4); 146.61 (C-25);
~
148.07 (C-23); 151.24 (C-2); 153.65 (C-27). IR (KBr):
n
(cmꢁ1) 1029s,
1167s, 1262vs; 1623m; 3083w. MS (ESI) m/z: 513 [(MꢁOTf)þ] (78).
HRMS (ESI) m/z: [(MꢁOTf)þ] (C27H24F3N2O3S) calcd: 513.1454,
found: 513.1454. Elem. Anal. Calcd for C28H24F6N2O6S2$(H2O)0.5 C,
50.07; H, 3.75; N, 4.17. Found: C, 49.81; H, 3.64; N, 4.14.
Following general procedure for helquat formation I with a re-
action time of 30 min and a reaction temperature of 90 ꢀC, and

L. Severa et al. / Tetrahedron 66 (2010) 3537–3552
3551
4.19.14. Helquat 40.
(dt, J¼8.3, 1.0 Hz, 1H, H-4); 8.83 (dd, J¼6.8, 0.9 Hz, 1H, H-3); 9.22
(ddt, J¼6.1, 1.6, 0.8 Hz, 1H, H-23); 9.23 (d, J¼6.8 Hz, 1H, H-2). 13C
NMR (151 MHz, acetone-d6): 28.08 (C-20); 29.38 (C-13); 32.40 (C-
12); 56.45 (C-11); 59.74 (C-21); 127.32 (C-24); 127.41 (C-15); 127.53
(C-16); 128.04 (C-3); 128.25 (C-4); 128.73 (C-7); 129.07 (C-10);
129.29 (C-26); 133.58 (C-6); 133.92 (C-19); 135.21 (C-18); 137.23 (C-
5); 138.24 (C-2); 139.69 (C-14); 139.85 (C-9); 141.33 (C-17); 146.36
(C-25); 147.06 (C-27); 147.75 (C-23); 155.78 (C-8). IR (thin film):
~
n
(cmꢁ1) 1030s; 1161s; 1226s; 1258s; 1510m; 1567m; 1625m;
3546m. MS (ESI) m/z: 499.1 [(MꢁOTf)þ] (100); 350.3 [(M-2OTf)2þ
]
(5); 349.2 (10); 321.3 (5). HRMS (ESI) m/z: [(MꢁOTf)þ]
Following general procedure for helquat formation II and gen-
eral workup procedure I using pure ethyl acetate, [Rh(PPh3)3Cl]
(C26H22F3N2O3S) calcd: 499.1298; found: 499.1300.
(1.0 mg, 1.08
39 (12.2 mg, 18.8
a white solid in 84% yield (10.4 mg, 15.8
m
mol, 6 mol %) and a solution of organic dication salt
mol, 1 equiv) in DMF (1.2 mL) gave helquat 40 as
mol).
m
Acknowledgements
m
Rf [SiO2, Stoddart’s magic mixture]: 0.37. Mp 297–299 ꢀC. 1H
NMR (600 MHz, acetone-d6): 2.59 (broad td, J¼14.0, 7.5 Hz, 1H, H-
19a); 2.80–2.86 (m,1H, H-20a); 2.99–3.06 (m,1H, H-20b); 3.24 (ddd.
J¼14.6, 7.0, 1.2 Hz, 1H, H-19b); 3.64 (ddd, J¼16.4, 3.5, 1.8 Hz, 1H, H-
12a); 3.74 (dddt, J¼16.4, 15.0, 4.6, 1.2 Hz, 1H, H-12b); 5.12 (broad td,
J¼14.4, 3.5 Hz, 1H, H-11a); 5.36 (dddd, J¼13.8, 4.6, 1.8, 0.6 Hz, 1H, H-
11b); 5.48 (ddd, J¼13.4, 7.0, 1.3 Hz, 1H, H-21a); 5.52 (td, J¼13.5,
5.6 Hz, 1H, H-21b); 7.63 (broad dd, J¼8.0, 1.5 Hz, 1H, H-26); 7.85
(ddd, J¼8.7, 6.9, 1.2 Hz, 1H, H-6); 8.00 (ddd, J¼7.7, 6.1, 1.5 Hz, 1H, H-
24); 8.01 (ddd, J¼8.1, 6.9, 1.0 Hz, 1H, H-5); 8.05 (broad d, J¼7.8 Hz,
1H, H-17); 8.08 (td, J¼7.8, 1.6 Hz, 1H, H-25); 8.11 (dq, J¼8.7, 0.9 Hz,
1H, H-7); 8.14 (broad d, J¼7.8 Hz, 1H, H-18); 8.30 (ddt, J¼8.1, 1.2,
0.7 Hz, 1H, H-4); 8.60 (dd, J¼6.6, 0.7 Hz, 1H, H-3); 9.08 (broad d,
J¼6.7 Hz, 1H, H-2); 9.38 (ddd, J¼6.1, 1.6, 0.5 Hz, 1H, H-23). 13C NMR
(151 MHz, acetone-d6): 29.02 (C-12); 29.71 (C-19); 32.74 (C-20);
56.30 (C-11); 59.01 (C-21); 126.16 (C-3); 127.27 (C-7); 127.45 (C-10 &
C-14); 128.70 (C-24); 128.96 (C-4); 132.11 (C-6); 132.55 (C-15);
132.70 (C-26); 133.24 (C-18); 135.95 (C-17); 136.36 (C-5); 138.11 (C-
2); 139.69 (C-9); 140.79 (C-16); 142.49 (C-13); 146.34 (C-25); 147.69
~
Support of this work by the Grant Agency of the Czech Republic
(203/09/0705 and 203/09/1614) and the IOCB (Z4 055 0506 and
IOCB Postdoctoral Fellowship to L.A.) is very appreciated. I.C. thanks
ˇ
MSM0021620857. We also thank the group of Dr. J. Cvacka for mass
spectra.
Supplementary data
Supplementary data (scans of NMR spectra of all compounds,
experimental procedures for compounds 2, 21, 37, and X-ray crys-
tallographic data of compounds 18, 29, 35, and 43) can be found.
Supplementary data associated with this article can be found, in the
online version, at doi:10.1016/j.tet.2010.03.007.
References and notes
1. (a) Sliwa, W. Curr. Org. Chem. 2003, 7, 995; (b) Ihmels, H. In Science of Synthesis;
Black, D., Ed.; Georg Thieme: Stuttgart, 2004; Vol. 15, p 907; (c) Arai, S.; Hida, M.
In Adv. Heterocycl. Chem.; Katritzky, A. R., Ed.; Academic: San Diego, 1992; Vol.
55, p 261.
(C-23); 150.74 (C-8); 153.35 (C-27). IR (thin film):
n
(cmꢁ1) 1029s;
2. (a) Loew, L. M. Pure Appl. Chem. 1996, 68, 1405; (b) Kuimova, M. K.; Botchway, S.
W.; Parker, A. W.; Balaz, M.; Collins, H. A.; Anderson, H. L.; Suhling, K.; Ogilby, P.
R. Nature Chem. 2009, 1, 69; (c) Reeve, J. E.; Collins, H. A.; Mey, K. D.; Kohl, M.
M.; Thorley, K. J.; Paulsen, O.; Clays, K.; Anderson, H. L. J. Am. Chem. Soc. 2009,
131, 2758.
1155s; 1225s; 1259s; 1509m; 1559m; 1625m; 3580m. MS (ESI) m/z:
499.1 [(MꢁOTf)þ] (100); 350.3 [(M-2OTf)2þ] (10); 349.2 (20). HRMS
(ESI) m/z: [(MꢁOTf)þ] (C26H22F3N2O3S) calcd: 499.1298; found:
499.1301. Elem. Anal. Calcd for C27H22F6N2O6S2$(H2O)0.5: C, 49.32;
H, 3.53; N, 4.26. Found: C, 49.37; H, 3.44; N, 3.93.
´
3. Coe, B. J.; Harris, J. A.; Brunschwig, B. S.; Garın, J.; Orduna, J. J. Am. Chem. Soc.
2005, 127, 3284.
4. Hammond, D. M.; Manetto, A.; Gierlich, J.; Azov, V. A.; Gramlich, P. M. E.; Burley,
G. A.; Maul, M.; Carell, T. Angew. Chem., Int. Ed. 2007, 46, 4184 and references
therein.
4.19.15. Helquat 43.
5. (a) Monchaud, D.; Teulade-Fichou, M. P. Org. Biomol. Chem. 2008, 6, 627; (b)
Granzhan, A.; Ihmels, H.; Ja¨ger, K. Chem. Commun. 2009, 1249; (c) Parenty, A. D.
C.; Smith, L. V.; Guthrie, K. M.; Long, D.-L.; Plumb, J.; Brown, R.; Cronin, L. J. Med.
Chem. 2005, 48, 4504; (d) Fromhertz, P.; Rieger, B. J. Am. Chem. Soc. 1986, 108,
5361.
6. Balzani, V.; Credi, A.; Raymo, F. M.; Stoddart, J. F. Angew. Chem., Int. Ed. 2000, 39,
3348.
7. Bica, K.; Gaertner, P. Eur. J. Org. Chem. 2005, 3235.
8. (a) Nicolas, C.; Lacour, J. Org. Lett. 2006, 8, 4343; (b) Procuranti, B.; Connon, S. J.
Org. Lett. 2008, 10, 4935 and references therein.
ˇ
ˇ
ˇ
9. (a) Adriaenssens, L.; Severa, L.; Sa´lova´, T.; Cı´sarov
a´, I.; Pohl, R.; Saman, D.; Ro-
ˇ
´
cha, S. V.; Finney, N. S.; Pospı´sil, L.; Slavıcek, P.; Teply, F. Chem.dEur. J. 2009, 15,
´ˇ
Following general procedure for helquat formation II and gen-
ꢀ
ˇ
ꢀ
´
´
´
´
´
´
1072; (b) Adriaenssens, L.; Severa, L.; Vavra, J.; Salova, T.; Hyvl, J.; Cızkova, M.;
Pohl, R.; Saman, D.; Teply´, F. Collect. Czech. Chem. Commun. 2009, 74, 1023.
ˇ
eral workup procedure II, [Rh(PPh3)3Cl] (2.5 mg, 2.7
and a solution of organic dication salt 42 (23.2 mg, 35.8
m
mol, 8 mol %),
mol,
10. For reviews on helicenes and heterohelicenes, see: (a) Rajca, A.; Miyasaka, M. In
Functional Organic Materials; Mu¨ ller, T. J. J., Bunz, U. H. F., Eds.; Wiley-VCH:
Weinheim, 2007; p 543; (b) Urbano, A. Angew. Chem., Int. Ed. 2003, 42, 3986; (c)
Hopf, H. Classics in Hydrocarbon Chemistry: Syntheses, Concepts, Perspectives;
Wiley-VCH: Weinheim, 2000; p 323; (d) Katz, T. J. Angew. Chem., Int. Ed. 2000,
39, 1921; (e) Collins, S. K.; Vachon, M. P. Org. Biomol. Chem. 2006, 4, 2518; (f)
Sato, K.; Arai, S. Research Signpost: Trivandrum In Cyclophane Chemistry for the
21st Century; Takemura, H., Ed.; 2002; p 173 For recent work; (g) Storch, J.;
m
1 equiv) in DMF (2.3 mL) gave helquat 43 as a yellow glass, which
solidified to a yellow solid after one week, in 99% yield (23.0 mg,
35.5 mmol).
Rf [SiO2, Stoddart’s magic mixture]: 0.32. Mp 240–243 ꢀC. 1H
NMR (600 MHz, acetone-d6): 2.60–2.72 (m, 2H, H-12a & H-13a);
2.93–2.98 (m, 1H, H-12b); 3.20–3.25 (m, 1H, H-13b); 3.66–3.74 (m,
2H, H-20); 5.10 (td, J¼13.8, 5.8 Hz, 1H, H-21a); 5.33–5.42 (m, 2H, H-
11); 5.34 (dd, J¼13.9, 6.2 Hz, 1H, H-21b); 7.46 (broad dd, J¼8.3,
1.4 Hz, 1H, H-26); 7.83 (ddd, J¼8.8, 6.9, 1.2 Hz, 1H, H-6); 7.91 (ddd,
J¼7.7, 6.1, 1.4 Hz, 1H, H-24); 7.97 (dq, J¼8.8, 1.0 Hz, 1H, H-7); 8.04
(td, J¼8.0, 1.6 Hz, 1H, H-25); 8.05 (d, J¼7.7 Hz, 1H, H-18); 8.12 (dt,
J¼7.7, 0.8 Hz, 1H, H-19); 8.14 (ddd, J¼8.3, 6.9, 1.1 Hz, 1H, H-5); 8.43
ꢀ
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16. See Experimental section and Supplementary data section for full experimental
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17. Combination count is enumerated using a formula for combination without
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