Exploration of 9-bromo[7]helicene reactivity

Article abstract of DOI:10.1016/j.tet.2013.05.039

Exploration of 9-bromo[7]helicene reactivity mainly in Pd-catalyzed reactions is reported. Palladium catalyzed carbon-carbon and carbon-heteroatom coupling reactions provide a large portfolio of racemic helicenes bearing different functional groups in good to excellent yields. Many of the reactions were performed in the microwave reactor keeping reaction time to a minimum compared with conventional synthetic methods.

Full text of DOI:10.1016/j.tet.2013.05.039

Accepted Manuscript
Exploration of 9-bromo[7]helicene reactivity
Jaroslav Žá dný , Petr Velíšek, Martin Jakubec, Jan Sý kora, Vladimír Církva, Jan
Storch
PII:
S0040-4020(13)00774-6
10.1016/j.tet.2013.05.039
TET 24377
DOI:
Reference:
To appear in: Tetrahedron
Received Date: 29 December 2012
Revised Date: 30 April 2013
Accepted Date: 13 May 2013
Please cite this article as: Žá dný J, Velíšek P, Jakubec M, Sý kora J, Církva V, Storch J, Exploration of 9-
bromo[7]helicene reactivity, Tetrahedron (2013), doi: 10.1016/j.tet.2013.05.039.
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Jaroslav Žádný, Petr Velíšek, Martin Jakubec, Jan Sýkora, Vladimír Církva and Jan Storch*
Institute of Chemical Process Fundamentals, v.v.i., AS CR, Rozvojová 2/135, Prague 6, 165 02

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Tetrahedron
journal homepage: www.elsevier.com
Exploration of 9-bromo[7]helicene reactivity
Jaroslav Žádnýa, Petr Velíšeka, Martin Jakubeca, Jan Sýkoraa, Vladimír Církvaa and Jan Storcha,*
a
Institute of Chemical Process Fundamentals, v.v.i., AS CR, Rozvojová 2/135, Prague 6, 165 02
ARTICLE INFO
ABSTRACT
Article history:
Received
Received in revised form
Accepted
Exploration of 9-bromo[7]helicene reactivity mainly in Pd-catalysed reactions is reported.
Palladium catalysed carbon – carbon and carbon – heteroatom coupling reactions provide a large
portfolio of racemic helicenes bearing different functional groups in good to excellent yields.
Many of the reactions were performed in the microwave reactor keeping reaction time to a
minimum compared with conventional synthetic methods.
Available online
2009 Elsevier Ltd. All rights reserved.
Keywords:
Helicene
Palladium Cross-coupling
Microwave-assisted Synthesis
1. Introduction
microwave-assisted transformations with emphasis on keeping
reaction time to a minimum compared with conventional and
[n]Helicenes, a class of intriguing compounds with fully
conjugated aromatic system and a non-planar topology, have
attracted considerable attention due to their unique properties and
potential applications.1 Among them they are promising as chiral
catalysts2 and ligands3 in asymmetric syntheses. They have been
employed in various areas of chemical sciences, including
supramolecular chemistry4 and molecular recognition.5
[7]Helicene is a particularly interesting [n]helicene with complete
one full turn of the helix and high optical stability (racemization
barrier is 40.5 kcal mol-1).6 It has been shown that [7]helicene can
act as a “molecular tweezer” for a silver cation,7 computational
studies for other metallic cations have been published.8 Its
deposition onto metal surfaces were also investigated.9 In
comparison to [5]- and [6]helicene, the heptaderivative has been
scarcely explored maybe due to its lower synthetic availability.
In this article, we describe the synthesis and characterization
of eleven novel racemic [7]helicenes with versatile functionality
enabling further derivatization. Starting material 9-
bromo[7]helicene 1 is commercially available and the bromine
atom serves as a good starting point for introducing different
functional groups. The reactivity of 1 is quite unexplored in
helicene chemistry and such a similar complex study of bromine
helicene derivative was performed only on their [5]helicene
analogues.10 We have focused on palladium catalyzed
known synthetic methods and up-to-date protocols.
2. Results and Discussion
Aiming for metal surface modification by helicenes we
prepared sulfur containing structures (Scheme 1). We improved a
published Pd catalyzed C-S coupling reaction10 in the sense of
time consumption. Employing microwave assisted chemistry we
succeed in reduction of the reaction time from 14 hours to 30
minutes. This also brings an advantage in avoiding the use of the
high boiling solvents (such as DMSO) that are problematic to
remove from the product. Using an excess of sodium
methylthiolate in the presence of Pd(PPh3)4 in ethanol at 170 °C
for
30
min
provided
the
corresponding
yield after
9-(methylsulfanyl)[7]helicene
2
in 85%
recrystallization from DCM/EtOH. Moreover it was confirmed
that this protocol can be used for preparation of other thioethers.
Subsequent treatment of 2 with an excess of t-BuSNa in DMF
under microwave conditions gave 9-sulfanyl[7]helicene 3 in
good yield, however rapid decomposition occurred within an
hour. This procedure for obtaining the desired thio-helicenes
seems to be the easiest despite the fact that thiols can be
synthesized directly form 1 analogously to Yi and coworkers.11
Corresponding author. Tel.: +420-220-390-272; fax: +420 220 920 661; e-mail: storchj@icpf.cas.cz

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2
Tetrahedron
Scheme 1. Introducing of thio group
Helicenes are potentially interesting chiral frameworks for
building new chiral phosphines. Thus we decided to explore
synthetic routes to the novel [7]helicenyl diphenylphosphine 4.
Being inspired by the methodology of Kappe,12 1 was converted
to diphenylphosphine on reaction with Ph2PH, KOAc and a
catalytic amount of Herrmann I catalyst (trans-bis(acetato)bis[o-
(di-o-tolylphosphino)benzyl]dipalladium(II))13 in a microwave
initiator (Scheme 2). After conversion into borane complex the
crude reaction mixture was purified by flash chromatography on
a silica gel yielding desired product 4. Compound 4 is stable in a
solid state towards oxidation under air atmosphere for days. The
free phosphine can be quantitatively converted to corresponding
phosphinoxide 5 by washing with 25% H2O2.
Scheme 4. Buchwald–Hartwig amination
The reactivity of 1 was also tested in relatively unexplored
cross-coupling reactions (Scheme 5). We employed Sonogashira
conditions with trimethylsilylacetylene in the presence of
Pd(PPh3)2Cl2, CuI, and triethylamine. This provided high yield of
9-(trimethylsilylethynyl)[7]helicene 10. Similarly, a Pd-catalyzed
Miyaura-Suzuki coupling with phenylboronic acid in the
presence of Pd2dba3, XPhos and K3PO4 as a base led to 9-
phenyl[7]helicene 9 in 80% yield.
Scheme 2. Introducing of phosphine group
Another interesting functionality is
a hydroxyl group.
Microwave conditions were used to transfer the oxygen atom into
the structure of [7]helicene again. Using a catalytic system
consisting of Herrmann I,13 XPhos and K2CO3 in an inert pre-
bubbled DMF/H2O (9:1) mixture led to the 9-
hydroxyl[7]helicene 6 as yellow solid in 20% yield after a
chromatographic separation (Scheme 3). An easier way to reach
the desired hydroxyl containing compound is described below
(Scheme 6). However, the product decomposes during an hour,
as observed by NMR.
Scheme 5. C-C couplings
Aryl boronate esters are of great importance in organic
synthesis, in particular as a substrate for their ability to form C-C
bonds through Suzuki-Miyaura coupling. The cross-coupling
reaction of aryl boronic acids esters with aryl halides or aryl
triflates has become one of the most widely applied methods for
constructing unsymmetrical biaryl systems. Miyaura reported the
preparation of aryl boronates from aryl halide and
bis(pinacolato)diboron (Pin2B2) using palladium catalysis.14 In
the course of our studies, we investigated the borylation reaction
of Pin2B2 with 1 under the standard conditions (Pd(dppf)Cl2,
KOAc, DMF) and helicenyl boronate 11 was obtained in good
yield (Scheme 6). Moreover, this derivative can act as a starting
material for other reactions. Being inspired by Marder et al.16 we
transformed 11 into 6 giving a better yield (45%) compared with
direct Pd-catalysed C-O coupling reaction.
Scheme 3. Pd-catalyzed hydroxylation
Aromatic amines are important intermediates of great interest.
One of the most powerful methods for preparing a variety of
arylamines from aryl halides and amines catalyzed by palladium
complexes was discovered by Buchwald and Hartwig.15 We
applied their chemistry to the preparation of helicene amines
(Scheme 4). Accordingly, on treatment of 1 with benzylamine or
benzophenone imine under the standard reaction conditions,
derivatives 7 and 8 were prepared in good or high yield and
isolated as hydrochlorides.
Scheme 6. Borylation and subsequnt hydroxylation
Besides palladium catalyzed cross coupling reactions we also
tried to transform 1 into the 9-cyano[7]helicene by Rosenmund-
von Braun reaction with CuCN in 1-methyl-2-pyrrolidinone

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3
under MW conditions (Scheme 7). Microwave assisted reaction
again brings a significant reduction of a reaction time and 12 was
obtained in an excellent yield of 80% after recrystalization from
DCM/EtOH mixture.
(methylsulfanyl)[7]helicene (2) (121.3 mg, 85 %) as a yellow
1
powder with mp 221 – 223 °C. H NMR (500 MHz, CDCl3): δ
2.80 (s, 3H), 6.40 (m, 2H), 6.90 (m, 2H), 7.06 (d, J=8.5, 1H),
7.10 (d, J=8.4, 1H), 7.29 (d, J=8.0, 2H), 7.46 (d, J=8.5, 1H), 7.49
(d, J=8.5, 1H), 7.69 (d, J=8.5, 1H), 7.73 (d, J=8.4, 1H), 7.88 (s,
1H), 7.91 (d, J=8.2, 1H), 7.94 (d, J=8.2, 1H), 7.98 (d, J=8.5, 1H),
8.50 (d, J=8.5, 1H) ppm. 13C NMR (125 MHz, CDCl3): δ 16.72
(q), 122.5 (d), 123.6 (d), 123.7 (d), 123.7 (s), 123.8 (d), 124.2 (d),
124.6 (d), 124.9 (d), 124.9 (d), 125.4 (d), 125.6 (d), 126.0 (d),
126.5 (d), 126.6 (d), 126.8 (s), 127.0 (d), 127.4 (d), 127.6 (d),
127.9 (d), 128.4 (s), 128.4 (s), 129.3 (s), 129.6 (s), 130.5 (s),
130.5 (s), 130.7 (s), 131.7 (s), 131.7 (s), 131.7 (s), 134.5 ppm. IR
(CHCl3): 3052 m, 2924 w, 2861 vw, 2831 vw, 1618 vw, 1603 w,
1595 w, 1569 w, 1553 vw, 1520 vw, 1508 w, 1497 w, 1470 w,
1457 vw, 1439 w, 1420 w, 1388 w, 1382 w, 1376 w, 1362 vw,
1339 vw, 1317 w, 1284 w, 1264 w, 1239 w, 1183 vw, 1176 vw,
1153 w, 1136 w, 1125 w, 1109 vw, 1070 vw, 1036 w, 979 w, 969
w, 960 w, 952 w, 915 w, 891 w, 867 w, 860 m, 846 w, 829 vs,
818 w, 714 w, 706 vw, 694 vw, 682 vw, 648 w, 633 m, 624 w,
610 m, 592 vw, 578 vw, 561 w, 542 vw, 537 vw, 523 m, 513 w,
489 w, 476 w, 472 w, 463 vw, 456 vw, 434 vw cm-1. EI MS: 424
(M+•, 100), 409 (13), 376 (24), 350 (16), 337 (5), 187 (13), 181
(5). HR EI MS: calculated for C31H20S 424.1286, found
424.1295.
CuCN (5 equiv)
1
MW, NMP, 3 h
CN
12 80%
Scheme 7. Cu(I)-mediated cyanation
3. Conclusion
In summary, efficient protocols for microwave assisted
palladium- and copper-catalyzed transformations starting from
commercially available 9-bromo[7]helicene were developed
leading to a novel portfolio of B, C, N, P, O, S substituted
[7]helicenes potentially applicable in many fields of chemistry,
physics and material science, opening promising and larger use
of helicenes.
4. Experimental Section
4,2,2. 9-Sulfanyl[7]helicene (3). Method A: An oven-dried
Schlenk flask was charged with 1 (193.9 mg, 0.424 mmol),
sodium thiosulfate (263.0 mg, 1.060 mmol, 2.5 eq), cesium
carbonate (276.3 mg, 0.848 mmol, 2.0 eq), Pd(dba)2 (4.9 mg, 8.5
µmol, 0.02 eq) and Xphos (8.1 mg, 17.0 µmol, 0.04 eq). The tube
was evacuated and backfilled with argon three times before the
solvent mixture (tBuOH/toluene = 4 : 6) was added. The mixture
was stirred until homodisperse at rt. An aliquot (15 µL) of water
was added via syringe. Then the tube was stirred at 80 °C for 24
h. The solid substance was separated from the reaction mixture
and was washed with ether. Zn dust (0.5 g) and HCl (10%, 5 mL)
was added to the solid substance with cooling by ice-water. After
stirring for 1 h, the mixture was extracted with ethyl acetate. The
organic layer was washed with H2O and brine and dried over
Na2SO4. Removal of solvent in vacuo provided 9-
sulfanyl[7]helicene (3) (76.5 mg, 44%) with a satisfactory purity
as a yellow powder.
Method B: A 20 mL microwave vial was charged with 2 (63.4
mg, 0.149 mmol) and sodium 2-methyl-2-propanethiolate (90%,
130.3 mg, 1.045 mmol, 7.0 eq). The vial was sealed with PTFE
septa and evacuated and backfield with argon for three times
before the anhydrous DMF (15 mL) was added. The inert gas
was bubbled through the reaction mixture for 20 min in order to
remove the oxygen. The mixture was heated to 220 °C for 320
min in a microwave initiator. The tube was cooled to 0 °C and
HCl (3 M, 2 mL) was added at once. The crude pale yellow
product was extracted between toluene and HCl. Organic layer
was dried over Na2SO4 and filtered. After removal of solvent the
crude product was collected and filtration on a short silica gel pad
4.1. General
1H and 13C{1H} spectra were recorded using a 500 MHz
instrument. Chemical shifts are reported in ppm (δ) relative to
TMS, referenced to signal CDCl3 (δ = 7.26 ppm and δ = 77.00
ppm respectively); CD2Cl2 (δ = 5.32 ppm and δ = 54.00 ppm
respectively); CD3OD (δ = 3.31 ppm and δ = 49.00 ppm
respectively); DMSO-d6 (δ = 2.50, 3.33 ppm and δ = 39.52 ppm
respectively). Electron impact (EI) mass spectra were determined
at an ionising voltage of 70 eV. TLC was performed on Silica gel
60 F254-coated aluminium sheets and compounds were
visualized by UV light (254 nm). Column chromatography was
performed on HPFC Biotage system with pre-packed flash silica
gel columns. Microwave experiments were performed on Anton
Paar Monowave 300 equipped with simultaneous temperature
measurement with IR and fiberoptic sensor and Biotage Initiator
Microwave Synthesizer. Commercially available reagent grade
materials were used as received. THF and Et2O were freshly
distilled from sodium/benzophenone under an atmosphere of
nitrogen. 9-Bromo[7]helicene was purchased from Lach-ner
s.r.o., Czech Republic.
4.2. Procedure for the transformation of 1
4.2.1. 9-(Methylsulfanyl)[7]helicene (2). A 20 mL microwave
vial was charged with
1
(176.6 mg, 0.386 mmol),
tetrakis(triphenylphosphine)palladium (35.7 mg, 0.031 mmol, 8
mol %) and sodium thiomethylate (90%, 150.3 mg, 1.678 mmol,
5.0 eq). Absolute ethanol (15 mL) was added and the vial was
capped with a PTFE septa. The inert gas was bubbled through the
solution for 10 min via needle. The reactor was placed then into
the microwave initiator and was reacted at 170 °C for 30 min.
The solvent was evaporated at the reduced pressure and the
compound was extracted by ether (30 mL). The organic layer was
washed three times with water (50 mL) and brine. Aqueous phase
was washed by ether and organic fractions were collected and dry
over NaSO4. The sulfate was filtered off and the solvent was
evaporated to dryness. The crude material was dissolved in an
aliquot of DCM and EtOH was added to form a yellow
precipitate. The mother liquor was filtered off and the product
was washed with EtOH. Recrystallization gives 9-
was performed using toluene as
a solvent to give 9-
sulfanyl[7]helicene (3) (53.3 mg, 87 %) with a satisfactory purity
as a yellow powder with mp 177 – 180 °C. The colour change is
1
caused by the decomposition of the compound. H NMR (500
MHz, CDCl3): δ 3.88 (s, 1H), 6.37 – 6.45 (m, 2H), 6.91 (m, 2H),
7.04 (d, J=8.5, 1H), 7.08 (d, J=8.6, 1H), 7.29 (d, J=8.0, 2H), 7.47
(d, J=8.4, 1H), 7.50 (d, J=8.5, 1H), 7.69 (d, J=8.5, 1H), 7.74 (d,
J=8.5, 1H), 7.88 (d, J=8.2, 1H), 7.91 (d, J=8.2, 1H), 8.00 (d,
J=8.5, 1H), 8.13 (s, 1H), 8.42 (d, J=8.4, 1H) ppm. 13C NMR (125
MHz, CDCl3): δ 123.5 (d), 123.7 (d), 123.8 (d), 124.1 (d), 124.6
(d), 124.7 (s), 125.0 (d), 125.0 (d), 125.4 (d), 125.6 (d), 125.8 (d),
126.3 (s), 126.3 (s), 126.59 (d), 126.6 (d), 127.3 (d), 127.7 (d),

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4
Tetrahedron
127.8 (d), 128.1 (d), 128.27 (s), 128.28 (s), 129.0 (d), 129.2 (s),
purified by flash chromatography (20 to 30 % acetone in hexane)
to give (9 [7]helicenyl)diphenylphosphine oxide (5) in two steps
(36.0 mg, 70%) as a yellow oil which solidified upon standing.
1H NMR (500 MHz, CDCl3): δ 6.42 (m, 2H), 6.91 (m, 2H), 7.01
(d, J=8.4, 1H), 7.04 (d, J=8.4, 1H), 7.29 (m, 2H), 7.46 – 7.53 (m,
4H), 7.53 – 7.60 (m, 3H), 7.64 (m, 1H), 7.66 (d, J=8.5, 1H), 7.69
(d, J=8.5, 1H), 7.78 (d, J=8.2, 1H), 7.81 – 7.88 (m, 6H), 7.90 (d,
J=8.2, 1H), 8.76 (dd, J=8.5, 1.0, 1H) ppm. 13C NMR (125 MHz,
CDCl3): δ 123.8 (d), 124.1 (d), 124.2 (d), 124.4 (d), 125.0 (d),
125.3 (d), 125.39 (d), 125.40 (d), 125.8 (d, J = 5.5 Hz), 126.0 (s,
J = 8.7 Hz), 126.6 (d), 126.7 (d), 127.0 (d), 127.4 (s), 127.7 (s, J
= 2.7 Hz), 127.9 (d), 127.96 (d), 127.97 (d), 128.3 (s, J = 1.0 Hz),
128.5 (d), 128.6 (d), 128.7 (d), 128.73 (d), 128.8 (d), 129.2 (s),
129.3 (s), 129.4 (s), 129.6 (s), 130.64 (s), 131.6 (s, J = 8.3 Hz),
131.64 (s), 131.67 (s), 132.0 (d, J = 2.8 Hz), 132.1 (d, J = 2.8
Hz), 132.12 (d), 132.14 (s), 132.2 (d), 132.3 (d), 132.4 (d), 132.6
(s), 133.4 (s), 135.4 (d, J = 11.7 Hz). 31P NMR (202 MHz,
CDCl3): δ 33.65 (s) ppm. IR (CHCl3): 3079 w, 3054 w, 2986 m,
2929 m, 2856 w, 1618 vw, 1602 w, 1596 w, 1592 w, 1569 vw,
1521 w, 1508 vw, 1497 w, 1484 w, 1456 vw, 1438 s, 1421 vw,
1390 w, 1376 w, 1365 w, 1355 w, 1334 vw, 1320 w, 1310 w,
1285 w, 1263 w, 1243 w, 1185 m, sh, 1171 s, 1136 w, 1119 m,
1101 m, 1086 w, sh, 1071 w, 1057 vw, 1036 w, 1028 w, 999 w,
982 w, 962 w, 953 w, 916 w, 899 w, 888 vw, 868 w, 849 w, 832
vs, 822 w, 812 vw, 713 w, 696 s, 663 w, 649 w, 636 w, 626 w,
617 vw, 611 w, 597 m, 570 m, 563 m, 551 s, 531 m, 519 s, 504
w, 472 w, 464 w, 460 w cm-1. APCI MS: 579 ([M+H]+). HR
APCI MS: calculated for C42H28OP 579.18723, found 579.18707.
129.4 (s), 130.70 (s), 130.72 (s), 131.1 (s), 131.5 (s), 131.7 (s),
131.74 (s) ppm. ESI MS: 409 ([M-H]-). HR ESI MS: calculated
for C30H17S 409.10564, found 409.10569
4.2.3. Borane 9-(diphenylphosphanyl)[7]helicene complex (4). A
20 mL microwave vial was charged with 1 (176.8 mg, 0.387
mmol), KOAc (37.9 mg, 0.387 mmol, 1.0 eq), trans-di(µ-
acetato)bis[ortho-(di-orthotolylphosphino)benzyl]dipalladium(II)
(Herrmann I) (7.2 mg, 0.008 mmol,
2
mol%) and
diphenylphosphine (95%, 74 µL, 79.6 mg, 0.406 mmol, 1.05 eq)
and closed with PTFE septa in glovebox. Freshly distilled and
degassed THF (15 mL) was added under inert atmosphere. The
vial was placed into a microwave initiator and reacted for 50 min
at 130 °C. A solution of borane dimethyl sulfide complex (2.0 M,
270 µL in THF, 0.540 mmol, 1.4 eq) was added dropwise and
stirred at room temperature overnight. The crude reaction mixture
was filtered via silica gel pad eluted by THF. The volatile
compounds were removed at reduced pressure and the residue
was purified by
ethylacetate
a
:
flash chromatography (petrolethere
–
=
8
1) on silica gel to give borane
a
9-(diphenylphosphanyl)[7]helicene complex (4) (115.0 mg, 52%)
as a pale yellow powder with mp 212 – 216 °C. H NMR (500
1
MHz, CDCl3): δ 6.42 (m, 2H), 6.92 (m, 2H), 7.02 (d, J = 8.5 Hz,
1H), 7.06 (d, J = 8.6 Hz, 1H), 7.29 (m, 2H), 7.57 – 7.43 (m, 7H),
7.62 – 7.58 (m, 1H), 7.64 (d, J = 8.5 Hz, 1H), 7.69 (d, J = 8.5 Hz,
1H), 7.75 (d, J = 8.8 Hz, 1H), 7.77 (d, J = 8.3 Hz, 1H), 7.85 –
7.78 (m, 5H), 7.90 (d, J = 8.2 Hz, 1H), 8.33 (d, J = 8.5 Hz, 1H)
ppm. 13C NMR (125 MHz, CDCl3): δ 123.85 (d), 123.87 (s),
124.0 (d), 124.2 (d), 124.3 (s), 124.4 (d), 125.0 (d), 125.2 (d),
125.3 (d), 125.5 (d), 125.9 (d, J = 7.7 Hz), 126.1 (s, J = 7.5 Hz),
126.6 (d), 126.7 (d), 126.8 (d), 127.2 (d), 127.3 (s, J = 2.3 Hz),
127.93 (d), 127.94 (s), 128.0 (d, J < 1.0 Hz), 128.4 (d), 128.4 (s),
128.9 (d), 129.0 (d), 129.01 (d), 129.1 (d), 129.2 (s), 129.22 (s, J
= 17.7 Hz), 129.3 (s), 129.5 (s, J = 21.3 Hz), 130.1 (s, J = 11.7
Hz), 130.6 (s, J < 0.5 Hz), 131.3 (s, J = 9.8 Hz), 131.4 (d, J = 1.7
Hz), 131.4 (d, J = 1.5 Hz), 131.6 (s), 131.7 (s), 132.0 (s, J < 0.5
Hz), 133.4 (d), 133.5 (d), 133.6 (d), 133.7 (d), 136.0 (d, J = 7.8
Hz). 31P NMR (202 MHz, CDCl3): δ 22.02 (bs) ppm. 11B NMR
(160 MHz, CDCl3): δ –35.3 (bs) ppm. IR (CHCl3): 3079 w, 3055
w, 2408 m, sh, 2392 m, 2351 w, 1618 w, 1603 w, 1596 w, 1573
vw, 1569 vw, 1554 vw, 1521 w, 1509 vw, 1497 w, 1485 w, 1456
w, 1438 s, 1421 vw, 1390 vw, 1384 vw, 1375 vw, 1365 w, 1353
w, 1331 vw, 1320 w, 1285 w, 1265 w, 1243 w, 1230 vw, 1189 w,
1155 w, 1137 w, 1126 w, 1106 m, 1062 m, 1036 w, 1029 w,
1000 w, 978 w, 962 vw, 952 w, 915 w, 897 w, 868 w, 848 w, 832
vs, 713 vw, 694 m, 648 w, 637 w, 621 w, 610 m, 592 w, 561 w,
546 vw, 536 w, 523 m, 516 w, 498 w, 494 w, 486 w, 472 w, 455
w, 440 w cm-1. APCI MS: 563 ([M+H-BH3]+), 599 ([M+Na]+).
HR APCI MS: calculated for C42H28P 563.19231, found
563.19109.
4.2.5. 9-Hydroxyl[7]helicene (6). Method A: A 2 mL microwave
vial was charged with 1 (228.7 mg, 0.500 mmol), Herrmann I
(9.4 mg, 0.010 mmol, 2 mol%), XPhos (0.8 mg, 0.040 mmol, 4
mol%) and potassium carbonate (207.3 mg, 1.500 mmol, 3.0 eq).
The vial was capped with PTFE septa and solvent mixtrure
(DMF : H2O = 9 : 1, 5 mL) was added. The inert gas was
bubbled through the reaction mixture for 10 min in order to
remove the oxygen. It was reacted in a microwave initiator for 2
hours at 150 °C. HCl (2 M, 20 mL) was added and the reaction
mixture was extracted into EtOAc (20 mL). The organic layer
was washed with NaHCO3 and water, dried over Na2SO4 and
filtered. The solvents were removed at the reduced pressure and
the crude product was purified by flash chromatography (hexane
– acetone = 9 : 1) on silica gel to give 9-hydroxyl[7]helicene (6)
(39.0 mg, 20%) as a yellow powder, which turned brown after
decomposition.
Method B: A Schlenk flask was charged with 11 (60.3 mg, 0.120
mmol) and NaOH (28.7 mg, 0.717 mmol, 6.0 eq). The content
was dissolved in THF (5 mL) and an aqueous solution of H2O2
(30%, 73 µL, 0.717 mmol, 6.0 eq) was added dropwise under
argon. The raction was stirred for 30 min at room temperature
and extracted with EtOAc (50 mL), washed with water (50 mL),
brine (50 mL), dried over anhydrous MgSO4 and filtered. The
solvents were removed at the reduced pressure and the crude
product was purified by flash chromatography (hexane – acetone
= 9 : 1) on silica gel to give 9-hydroxyl[7]helicene (6) (21.1 mg,
4.2.4. (9-[7]Helicenyl)diphenylphosphine oxide (5). A 5 mL
microwave vial was charged with 1 (40.6 mg, 0.089 mmol),
KOAc (8.7 mg, 0.089 mmol, 1.0 eq), trans-di(µ-
acetato)bis[ortho-(di-ortho-
45%) as
a yellow powder, which turned brown after
tolylphosphino)benzyl]dipalladium(II) (Herrmann I) (1.6 mg,
0.002 mmol, 2 mol%) and diphenylphosphine (95%, 17 µL, 18.3
mg, 0.093 mmol, 1.05 eq) and closed with PTFE septa in
glovebox. Freshly distilled and degassed THF (3 mL) was added
under inert atmosphere. The vial was placed into a microwave
initiator and reacted for 30 min at 160 °C. The solvent was
removed at reduced pressure and the residue was dissolved in
DCM (20 mL) and washed with H2O2 (30%, 20 mL) in a
separation funnel. The organic layer was then washed with
saturated NaHCO3, H2O and brine and dried over Na2SO4. After
filtration the solvent was evaporated and the crude product was
1
decomposition. H NMR (500 MHz, CD2Cl2): δ 5.99 (bs, 1H),
6.39 (m, 2H), 6.90 (m, 2H), 7.12 (d, J=8.6, 1H), 7.16 (d, J=8.6,
1H), 7.31 (m, 2H), 7.37 (s, 1H), 7.46 (d, J=8.5, 1H), 7.53 (d,
J=8.5, 1H), 7.73 (d, J=8.5, 1H), 7.78 (d, J=8.5, 1H), 7.86 (d,
J=8.2, 1H), 7.90 (d, J=8.2, 1H), 7.99 (d, J=8.4, 1H), 8.44 (d,
J=8.4, 1H) ppm. 13C NMR (125 MHz, CD2Cl2): δ 108.0 (d),
120.6 (d), 121.4 (s), 123.9 (d), 124.1 (d), 124.7 (d), 125.0 (d),
125.3 (s), 125.4 (d), 125.5 (d), 126.3 (d), 126.34 (d), 126.4 (d),
126.7 (d), 127.08 (d), 127.10 (d), 127.6 (s), 127.65 (d), 128.1 (d),
128.5 (d) 128.7 (s), 129.1 (s), 129.8 (s), 130.12 (s), 130.14 (s),

ACCEPTED MANUSCRIPT
5
131.6 (s), 132.3 (s), 132.4 (s), 133.1 (s), 150.8 (s) ppm. APCI
MS: 393 ([M-H]-). HR APCI MS: calculated for C30H18O
393.12849, found 393.12784.
126.92 (d), 127.3 (s), 127.4 (s), 127.44 (d), 128.0 (d), 128.1 (d),
128.4 (s), 128.5 (s), 128.7 (d), 130.5 (s), 130.6 (s), 130.7 (s),
131.4 (s), 131.5 (s) ppm. IR (CHCl3): 3390 w, 3053 s, 3170 w,
br, sh, 2854 s, br, 2595 m, br, 2005 vw, br, 1627 w, 1601 w, 1596
w, 1578 w, 1555 vw, 1527 m, 1518 s, 1500 m, 1477 w, 1469 w,
1439 vw, 1430 w, 1422 vw, 1411 vw, 1399 w, 1378 w, 1363 w,
1322 w, 1290 w, 1271 w, 1248 w, 1238 w, 1186 vw, 1178 vw,
1158 w, 1145 w, 1137 w, 1104 vw, 1090 vw, 1080 vw, 1054 m,
1037 m, 1029 m, 1011 w, 977 vw, 960 w, 915 vw, 891 w, 877 w,
853 vw, 830 s, 819 w, 715 w, 704 vw, 695 vw, 687 vw, 648 w,
639 vw, 631 m, 611 w, 605 w, 576 w, 564 vw, 553 vw, 544 vw,
527 w, 521 m, 509 vw, 491 w, 478 w, 463 w, 446 vw, 436 vw
cm-1. ESI MS: 394 ([M+H]+). HR ESI MS: calculated for
C30H20N 394.15903, found 394.15906.
4.2.6. 9-(Benzylamino)[7]helicene hydrochloride (7). A flask was
charged with 1 (250.0 mg, 0.547 mmol), Cs2CO3 (427.9 mg,
1.313 mmol, 2.4 eq), BINAP (34.1 mg, 0.055 mmol, 0.1 eq) and
Pd(OAc)2 (12.3 mg, 0.055 mmol, 10 mol%). The content was
dissolved in toluene (18 mL) and benzylamine (178 µL, 1.641
mmol, 3.0 eq) was added. The flask was purged with inert gas
and a condenser was connected. It was reacted under reflux for 3
hours under inert gas. The crude reaction mixture was filtered
through a pad of silica gel eluting with toluene. The solvent was
evaporated at the reduced pressure and the residue was dissolved
in diethyl ether (10 mL). A solution of HCl (2.0 M, 0.5 mL, 1.00
mmol, 1.8 eq in ether) was added dropwise to form crystals of
product. The solvent was filtered off and the crude product was
washed with ether to give 9-(benzylamino)[7]helicene (7) (156.0
mg, 55%) in a satisfactory purity as a yellow powder with mp
4.2.8. 9-Phenyl[7]helicene (9). A Schlenk flask was charged with
1 (150.0 mg, 0.328 mmol), Pd(dba)2 (6.8 mg, 6.6 µmol, 2 mol%),
Xphos (6.3 mg, 13.0 µmol, 4 mol%), PhB(OH)2 (120 mg, 0.948
mmol, 3.0 eq) and K3PO4 (418 mg, 1.968 mmol, 6.0 eq). The
mixture was heated at 90°C for 5 h in toluene (10 mL) and then
cooled to room temperature. Crude reaction mixture was filtered
through a short pad of silica gel eluting with toluene. The
solvents were removed at the reduced pressure and the crude
product was purified by crystallization from DCM/EtOH mixture
yielding desired product (120.0 mg, 80%) as a yellow powder
1
144 °C decomp. H NMR (500 MHz, CD3OD): δ 4.86 (m, 4H),
6.36 (m, 2H), 6.88 (m, 2H), 6.95 (d, J=8.5, 1H), 6.98 (d, J=8.5,
1H), 7.29 (m, 2H), 7.32 – 7.41 (m, 3H), 7.46 (d, J=8.6, 1H), 7.50
– 7.57 (m, 3H), 7.72 (d, J=8.5, 1H), 7.80 (d, J=8.5, 1H), 7.88 (d,
J=8.3, 1H), 7.94 (d, J=8.2, 1H), 8.09 (d, J=8.6, 1H), 8.26 (d,
J=8.5, 1H) ppm. 13C NMR (125 MHz, CD3OD): δ 52.8 (t), 120.1
(d), 122.9 (s), 124.6 (d), 124.9 (d), 125.1 (d), 125.5 (d), 125.7 (s),
126.0 (d), 126.2 (d), 126.4 (d), 126.8 (d), 127.3 (d), 127.8 (d),
127.9 (d), 127.9 (d), 128.1 (s), 128.7 (d), 129.1 (d), 129.35 (d),
129.40 (d), 129.6 (s), 129.7 (s), 129.8 (d), 129.84 (d), 129.91 (d),
130.4 (s), 130.7 (s), 131.5 (s), 132.2 (s), 133.3 (s), 133.33 (s),
133.4 (s), 137.0 (s) ppm. IR (CHCl3): 3053 m, 2981 m, 2888 m,
br, 2713 m, 2637 m, 2584 m, 2559 m, 1740 w, 1681 vw, 1604 m,
1596 m, 1578 s, 1555 w, 1526 m, 1499 m, 1489 m, 1472 w, 1458
m, 1453 m, 1439 m, 1431 m, 1405 w, 1399 w, 1391 w, 1385 w,
1363 w, 1352 w, 1341 w, 1322 w, 1311 vw, 1289 w, 1276 w,
1270 w, 1246 m, 1198 vw, 1180 vw, 1164 w, 1158 w, 1143 vw,
1137 w, 1131 vw, 1128 vw, 1111 w, 1082 w, 1040 w, 1029 w,
1004 w, sh, 992 w, 960 w, 912 w, 892 w, 878 w, 869 w, 844 w,
831 s, 819 w, 716 w, 699 m, 645 w, 629 w, 612 w, 597 vw, 571
w, 564 w, 558 w, 521 m, 505 m, 478 w, 465 w, 410 w cm-1. ESI
MS: 484 ([M+H]+). HR APCI MS: calculated for C37H26N
484.20576, found 484.20598.
1
with mp 219 – 222 °C. H NMR (500 MHz, CDCl3): δ 6.44 (m,
2H), 6.93 (m, 2H), 7.18 (m, 2H), 7.32 (m, 2H), 7.51 (d, J = 9.0
Hz, 2H), 7.53 – 7.56 (m, 1H), 7.60 (t, J = 7.5, 2H), 7.70 – 7.75
(m, 4H), 7.86 (d, J = 8.5 Hz, 1H), 7.95 (d, J = 8.2 Hz, 1H), 7.98
(s, 1H), 8.01 (d, J = 8.2 Hz, 1H), 8.05 (d, J = 8.5 Hz, 1H) ppm.
13C NMR (125 MHz, CDCl3): δ 123.6 (d), 123.7 (d), 124.3 (d),
124.5 (d), 124.8 (d), 124.9 (d), 124.94 (d), 125.4 (d), 125.7 (d),
125.8 (s), 126.57 (d), 126.58 (d), 126.8 (d), 127.1 (d), 127.2 (d),
127.45 (d), 127.47 (d), 127.48 (d), 127.8 (d), 128.2 (s), 128.3 (s),
128.4 (d), 129.4 (s), 129.6 (s), 130.4 (s), 130.5 (s), 130.53 (d),
130.8 (s), 131.2 (s), 131.7 (s), 131.71 (s), 138.6 (s), 140.6 (s)
ppm. IR (CHCl3): 3084 w, sh, 3052 s, 3034 w, sh, 1620 w, 1600
m, 1574 vw, 1554 vw, 1524 vw, 1497 m, 1473 m, 1459 w, 1442
w, 1423 w, 1389 m, 1364 vw, 1342 vw, 1321 w, 1291 vw, 1278
vw, 1265 vw, 1250 vw, 1238 m, 1192 vw, 1179 vw, 1163 w,
1149 w, 1136 w, 1113 vw, 1073 w, 1030 w, 1000 vw, 968 w, 961
w, 953 w, 949 w, 918 vw, 911 vw, 891 m, 884 m, 868 w, 833 vs,
822 w, 716 m, 707 m, 701 m, 690 vw, 679 vw, 652 m, 643 m,
623 vw, 617 m, 611 s, 595 w, 578 w, 566 w, 533 vw, 523 s, 512
w, 502 w, 496 vw, 472 w, 434 vw, 420 vw cm-1. APCI MS: 455
([M+H]+). HR APCI MS: calculated for C36H23 455.17943, found
455.17871.
4.2.7. 9-(Amino)[7]helicene hydrochloride (8). A flask was
charged with 1 (100.0 mg, 0.219 mmol), Cs2CO3 (171.0 mg,
0.525 mmol, 2.4 eq), BINAP (13.6 mg, 0.022 mmol, 0.1 eq) and
Pd(OAc)2 (4.9 mg, 0.022 mmol, 0.1 eq). The content was
dissolved in toluene (15 mL) and benzophenone imine (119.0
mg, 110 µL, 0.657 mmol, 3.0 eq) was added. The flask was
purged with inert gas and a condenser was connected. It was
reacted under reflux for 5 hours under inert gas. The crude
reaction mixture was filtered through a pad of silica gel eluting
with toluene. The solvent was evaporated at the reduced pressure
and the residue was dissolved in diethyl ether (10 mL). A
solution of HCl (2.0 M, 0.2 mL, 0.4 mmol, 1.8 eq in ether) was
added dropwise to form crystals of product. The solvent was
filtered off and the crude product was washed with ether to give
9-amino[7]helicene (8) (90.0 mg, 95%) in satisfactory purity as a
yellow powder with mp 155 °C decomp. Further purification can
4.2.9. 9-Trimethylsilylethynyl[7]helicene (10). To a solution of 1
(150.0 mg, 0.328 mmol), Pd(PPh3)2Cl2 (46.0 mg, 66 µmol, 0.2
eq) and CuI (6.9 mg, 36 µmol, 0.11 eq) in triethylamine (10 mL)
was added trimethylsilylacetylene (64.4 mg, 93 µL, 0.656 mmol,
2.0 eq). The mixture was heated at 60°C for 15 h and then cooled
to room temperature. Crude reaction mixture was evaporated to
dryness, extracted with DCM and filtered through a short pad of
silica gel eluting with DCM. The solvents were removed at
reduced pressure and the crude product was purified by
crystallization from DCM/MeCN yielding the desired product
1
(115.0 mg, 74%) as a yellow powder with mp 207 – 210 °C. H
1
be achieved by crystallization from EtOH. H NMR (500 MHz,
NMR (500 MHz, CDCl3): δ 0.42 (s, 9H), 6.40 (m, 2H), 6.91 (m,
2H), 7.05 (d, J = 8.4 Hz, 1H), 7.08 (d, J = 8.5 Hz, 1H), 7.29 (d, J
= 7.9 Hz, 2H), 7.49 (d, J = 8.3 Hz, 1H), 7.50 (d, J = 8.2 Hz, 1H),
7.70 (d, J = 8.5 Hz, 1H), 7.74 (d, J = 8.5 Hz, 1H), 7.91 (d, J = 8.2
Hz, 1H), 7.94 (d, J = 8.2 Hz, 1H), 8.01 (d, J = 8.4 Hz, 1H), 8.28
(s, 1H), 8.56 (d, J = 8.3 Hz, 1H). 13C NMR (125 MHz, CDCl3): δ
0.2 (q), 99.9 (s), 103.3 (s), 119.2 (s), 123.7 (d), 123.8 (d), 124.1
(d), 124.4 (d), 124.7 (d), 125.0 (d), 125.1 (d), 125.4 (s), 125.5 (s),
DMSO-d6): δ 4.15 (bs, 2H), 6.39 (m, 2H), 6.89 – 6.98 (m, 4H),
7.40 (m, 2H), 7.61 (d, J = 8.5 Hz, 1H), 7.66 (d, J = 8.5 Hz, 1H),
7.88 (d, J = 8.5 Hz, 1H), 7.92 (d, J = 8.5 Hz, 1H), 8.11 – 8.21 (m,
3H), 8.23 (d, J = 8.5 Hz, 1H), 8.33 (d, J = 8.5 Hz, 1H) ppm. 13C
NMR (125 MHz, DMSO-d6): δ 118.7 (d), 120.7 (d), 123.0 (s),
123.2 (d), 123.6 (d), 123.7 (d), 123.8 (d), 125.2 (d), 125.3 (s),
125.33 (d), 125.5 (d), 125.7 (d), 125.73 (s), 126.5 (d), 126.9 (d),

ACCEPTED MANUSCRIPT
6
Tetrahedron
125.55 (d), 125.6 (d), 126.4 (d), 126.58 (d), 126.60 (d), 127.6
6.94 (m, 2H), 7.00 (d, J=8.4, 2H), 7.32 (d, J=8.0, 2H), 7.55 (d,
J=8.4, 1H), 7.56 (d, J=8.4, 1H), 7.73 (d, J=8.6, 1H), 7.75 (d,
J=8.6, 1H), 7.98 (m, 2H), 8.08 (d, J=8.4, 1H), 8.39 (d, J=8.4,
1H), 8.47 (s, 1H). 13C NMR (125 MHz, CDCl3): δ 108.5 (s),
118.2 (s), 123.3 (d), 123.8 (d), 124.0 (d), 124.03 (d), 124.2 (d),
125.4 (d), 125.42 (d), 125.44 (d), 125.5 (d), 126.3 (d), 126.8 (d),
126.82 (d), 127.5 (s), 127.9 (s), 128.1 (s), 128.4 (d), 128.7 (d),
129.0 (s), 129.02 (d), 129.1 (s), 129.3 (d), 129.7 (s), 123.0 (s),
131.3 (s), 131.8 (s), 131.83 (s), 132.5 (s), 133.8 (s), 133.82 (d)
ppm. IR (CHCl3): 3053 m, 2224 m, 1620 w, 1603 w, 1598 w,
1573 w, 1553 vw, 1523 w, 1512 vw, 1498 w, 1471 vw, 1461 vw,
1440 w, 1423 w, 1391 w, 1380 w, 1362 m, 1341 w, 1322 w,
1289 w, 1268 w, 1243 w, 1192 w, 1181 w, 1156 w, 1144 vw,
1138 w, 1036 w, 962 w, 954 w, 895 m, 887 w, 868 w, 833 vs,
820 w, 815 w, 718 w, 707 vw, 651 w, 642 m, 633 w, 617 vw, 609
m, 580 vw, 564 w, 554 w, 528 w, 521 m, 509 m, 498 w, 481 vw,
473 w, 465 vw, 454 w, 440 vw, 423 vw, 414 w, 408 vw cm-1. EI
MS: 403 (M+•, 100), 388 (18), 376 (34), 362 (18), 349 (6), 325
(13), 228 (24), 211 (15), 185 (17), 149 (10), 129 (8), 111 (11),
102 (17), 83 (18), 71 (23), 57 (33), 43 (37). HR EI MS:
calculated for C31H17N 403.1361, found 403.1360.
(d), 127.7 (d), 127.9 (d), 127.93 (d), 128.17 (s), 128.2 (s), 129.3
(s), 129.4 (s), 130.9 (s), 131.0 (s), 131.4 (s), 131.5 (s), 131.67 (d),
131.7 (s), 131.71 (s) ppm. IR (CHCl3): 3053 m, 2962 m, 2929 w,
2900 w, 2855 vw, 2795 vw, 2147 m, 1620 vw, 1603 w, 1573 vw,
1554 vw, 1520 vw, 1507 vw, 1497 w, 1484 vw, 1474 vw, 1457
vw, 1439 w, 1423 w, 1409 vw, 1388 w, 1380 vw, 1363 vw, 1358
vw, 1341 vw, 1322 w, 1288 w, 1269 m, 1262 m, 1251 s, 1243 m,
1196 vw, 1191 vw, 1177 vw, 1159 w, 1154 w, 1143 vw, 1134
vw, 1120 vw, 1090 w, 1079 w, 1043 m, 1037 w, 1024 m, 978
vw, 961 vw, 949 vw, 938 m, 893 m, 877 s, 852 vs, 847 vs, 837
vs, 832 vs, 820 m, 718 m, 699 w, 689 w, 663 vw, 651 m, 643 m,
629 w, 617 vw, 609 m, 599 vw, 578 vw, 564 vw, 542 w, 533 vw,
522 m, 505 m, 492 w, 470 w, 456 vw, 447 vw, 440 vw, 427 vw,
418 vw, 414 vw cm-1. EI MS: 474 (M+•, 100%), 459, 447, 433,
413, 400, 229, 216, 200, 187, 73. HR EI MS: calculated for
C35H26Si 474.1804, found 474.1809.
4.2.10.
9-(4,4,5,5-Tetramethyl-1,3,2-dioxaborolan-2-yl)-
[7]helicene (11). A 20 mL microwave vial was charged with 1
(310.4 mg, 0.679 mmol), bis(pinacolato)diboron (258.5 mg,
1.018 mmol, 1.5 eq), KOAc (199.8 mg, 2.036 mmol, 3.0 eq) and
Pd(dppf)Cl2 (14.9 mg, 0.020 mmol, 3 mol%). The vial was
capped with PTFE septa and DMF (15 mL) was added. The inert
gas was bubbled through the reaction mixture for 10 min in order
to remove the oxygen. It was reacted in a microwave initiator for
45 min at 140 °C. After the reaction the solvent was evaporated
at the reduced pressure and the residue was purified by a flash
chromatography on a silica gel (2 to 7 % acetone in hexane) to
give 9-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)[7]helicene
(11) (221.8 mg, 65%) as a yellow powder with mp 288 – 293 °C.
1H NMR (500 MHz, CDCl3): δ 1.27 (s, 6H), 1.53 (s, 6H), 6.39
(m, 2H), 6.89 (m, 2H), 7.04 (d, J=8.5, 1H), 7.06 (d, J=8.6, 1H),
7.28 (m, 2H), 7.47 (d, J=8.4, 1H), 7.48 (d, J=8.3, 1H), 7.71 (d,
J=8.6, 1H), 7.73 (d, J=8.6, 1H), 7.91 (d, J=8.1, 1H), 7.96 (d,
J=8.5, 1H), 8.05 (d, J=8.2, 1H), 8.65 (s, 1H), 8.97 (d, J=8.5, 1H)
ppm. 13C NMR (125 MHz, CDCl3): δ 25.0 (q), 25.0 (q), 25.05
(q), 25.07 (q), 83.5 (s), 84.0 (s), 123.5 (d), 123.7 (d), 124.3 (d),
124.5 (d), 124.6 (d), 124.8 (s), 124.9 (d), 125.5 (d), 125.6 (d),
126.47 (d), 126.5 (d), 127.0 (d), 127.03 (d), 127.06 (s), 127.09
(d), 127.35 (d), 127.37 (d), 127.7 (d), 128.1 (s), 128.2 (s), 129.3
(s), 129.5 (s), 130.4 (s), 130.7 (s), 131.5 (s), 131.54 (s), 131.6 (s),
134.8 (s), 137.17 (s), 137.2 (d) ppm. 11B NMR (160 MHz,
CDCl3): δ 30.6 (bs) ppm. IR (CHCl3): 3051 m, 3002 m, 2983 s,
2931 m, 2869 w, 2857 w, 1618 vw, 1599 w, 1572 w, 1554 vw,
1523 w, 1509 vw, 1496 w, 1478 m, 1470 w, 1458 w, 1440 m,
1428 w, 1403 m, 1392 m, 1381 s, 1373 s, 1350 m, 1316 s, 1298
s, sh, 1285 s, 1260 m, 1241 w, 1172 m, 1143 s, 1124 vs, 1108 m,
1083 vw, 1070 w, 1036 w, 1006 vw, 986 m, 960 m, 949 w, 920
vw, 908 w, 889 vw, 867 w, 847 s, 839 m, 833 m, 824 w, 815 vw,
715 vw, 705 vw, 693 vw, 683 vw, 647 w, 627 w, 618 m, 612 w,
588 vw, 579 w, 563 vw, 553 w, 522 m, 501 vw, 490 vw, 473 w,
417 vw cm-1. APCI MS: 505 ([M+H]+). HR APCI MS: calculated
for C36H30O2B 505.23334, found 505.23356.
Acknowledgment
We appreciate the financial support from the Grant Agency of
the Czech Republic (Grant No. P207/10/1124), the Technology
Agency of the Czech Republic (Grant No. TA01010646) and
Ministry of Industry and Trade of the Czech Republic (Grant No.
FR-TI3/628).
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Tanaka, K. J. Am. Chem. Soc. 2004, 126, 6566. (c) Zhigang; D.;
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4.2.11. 9-Cyano[7]helicene (12). A 20 mL microwave vial was
charged with 1 (152.3 mg, 0.333 mmol) and CuCN (149.1 mg,
1.665 mmol, 5.0 eq). The vial was capped with PTFE septa and
NMP (12 mL) was added. The inert gas was bubbled through the
reaction mixture for 10 min in order to remove the oxygen. It was
reacted in a microwave initiator for 3 hours at 210 °C. After the
reaction an aqueous solution of NH4OH (25%, 50 mL) was added
and the product was extracted with EtOAc, dried over MgSO4,
filtered and the solvent was evaporated at the reduced pressure. A
recrystallization from DCM/EtOH mixture gives 9-
cyano[7]helicene (12) (104.5 mg, 80%) as a yellow powder with
6. Martin, R. H.; Marchant M. J. Tetrahedron 1974, 30, 347.
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M.; Krossing I. Dalton Trans., 2012, 41, 8238.
1
mp 286 – 292 °C. H NMR (500 MHz, CDCl3): δ 6.43 (m, 2H),

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7
8. (a) Saini, S.; Deb, B. M. Ind. J. Chem., 2007, 46A, 9. (b)
Johansson, M. P.; Patzschke, M. Chem. Eur. J., 2009, 15, 13210.
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Chirality 2001, 13, 675. (c) Fasel, R.; Cossy, A. Ernst, K. H.,
Baumberger, F.; Greber, T.; Osterwalder, J. J. Chem. Phys. 2001,
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McFadden, C. F.; Hug, P.; Müller, U.; Ellerbeck, U.
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Teasley, M. F.; Gilbert, A. M.; Geiger, W. E.; Robben, M.
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Supplementary Material
Supplementary data, NMR spectra of all compounds are
available in the online version, at

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Exploration of 9-bromo[7]helicene reactivity
Jaroslav Žádný, Petr Velíšek, Martin Jakubec, Jan Sýkora, Vladimír Církva
and Jan Storch*
Institute of Chemical Process Fundamentals, v.v.i., AS CR, Rozvojová 2/135, Prague 6, 165 02
storchj@icpf.cas.cz
Supplementary Information
Index
General Considerations
Spectra
S2
S3
S1

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General Considerations
1H and 13C{1H} spectra were recorded using a 500 MHz instrument. Chemical shifts are reported in
ppm (δ) relative to TMS, referenced to signal CDCl3 (δ = 7.26 ppm and δ = 77.00 ppm respectively);
CD2Cl2 (δ = 5.32 ppm and δ = 54.00 ppm respectively); CD3OD (δ = 3.31 ppm and δ = 49.00 ppm
respectively); DMSO-d6 (δ = 2.50, 3.33 ppm and δ = 39.52 ppm respectively). Electron impact (EI)
mass spectra were determined at an ionising voltage of 70 eV. TLC was performed on Silica gel 60
F254-coated aluminium sheets and compounds were visualized by UV light (254 nm). Column
chromatography was performed on HPFC Biotage system with pre-packed flash silica gel columns.
Microwave experiments were performed on Anton Paar Monowave 300 equipped with simultaneous
temperature measurement with IR and fiberoptic sensor and Biotage Initiator Microwave
Synthesizer. Commercially available reagent grade materials were used as received. THF and Et2O
were freshly distilled from sodium/benzophenone under an atmosphere of nitrogen.
9-Bromo[7]helicene was purchased from Lach-ner s.r.o., Czech Republic.
Spectroscopic Data
S2

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8.5
8.0
7.5
7.0
6.5
6.0
5.5
f1 (ppm)
5.0
4.5
4.0
3.5
3.0

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135 130 125 120 115 110 105 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15
f1 (ppm)

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132.0 131.5 131.0 130.5 130.0 129.5 129.0 128.5 128.0 127.5 127.0 126.5 126.0 125.5 125.0 124.5 124.0 123.5 123.0
f1 (ppm)

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8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2
f1 (ppm)

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136.5
135.5
134.5
133.5
132.5
131.5
130.5
129.5
128.5
127.5
126.5
125.5
124.5
123.5
122.5
f1 (ppm)

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9.0 8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1
f1 (ppm)

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136.5
135.5
134.5
133.5
132.5
131.5
130.5
129.5
128.5
127.5
126.5
125.5
124.5
123.5
122.5
f1 (ppm)

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8.9 8.8 8.7 8.6 8.5 8.4 8.3 8.2 8.1 8.0 7.9 7.8 7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6.8 6.7 6.6 6.5 6.4 6.3 6.2 6.1 6.0 5.9 5.8 5.7 5.6
f1 (ppm)

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152 150 148 146 144 142 140 138 136 134 132 130 128 126 124 122 120 118 116 114 112 110 108 106
f1 (ppm)

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NH
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
f1 (ppm)

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NH
133
132
131
130
129
128
127
126
125
f1 (ppm)
124
123
122
121
120
119
118

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NH+3
8.6
8.5
8.4
8.3
8.2
8.1
8.0
7.9
7.8
7.7
7.6
7.5
7.4
f1 (ppm)
7.3
7.2
7.1
7.0
6.9
6.8
6.7
6.6
6.5
6.4
6.3
6.2

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+
3
NH
132.5 132.0 131.5 131.0 130.5 130.0 129.5 129.0 128.5 128.0 127.5 127.0 126.5 126.0 125.5 125.0 124.5 124.0 123.5 123.0 122.5 122.0 121.5 121.0 120.5 120.0 119.5 119.0 118.5
f1 (ppm)

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8.1
8.0
7.9
7.8
7.7
7.6
7.5
7.4
7.3
7.2
f1 (ppm)
7.1
7.0
6.9
6.8
6.7
6.6
6.5
6.4
6.3

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CH
3
Si
CH
3
H C
3
8.5
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
f1 (ppm)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5