Mild access to planar-chiral: Ortho -condensed aromatic ferrocenes via gold(i)-catalyzed cycloisomerization of ortho -alkynylaryl ferrocenes

Article abstract of DOI:10.1039/c6cc02624a

An efficient approach to (R_p) planar-chiral tri- and tetracyclic ortho-condensed aromatic ferrocenes was developed through the enantioselective cationic Au(i)-catalyzed cycloisomerization, in the presence of bidentate phosphine ligand (R)-DTBM-Segphos, from readily available ortho-alkynylaryl ferrocenes under very mild conditions (11 examples, up to 92% yield and 93% ee).

Full text of DOI:10.1039/c6cc02624a

View Article Online
View Journal
ChemComm
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: A. Urbano, G.
Hernandez-Torres, A. M. del Hoyo, A. Martinez-Carrion and M. C. Carreno, Chem. Commun., 2016, DOI:
10.1039/C6CC02624A.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/chemcomm

Please do not adjust margins
ChemComm
Page 1 of 5
View Article Online
DOI: 10.1039/C6CC02624A
ChemComm
COMMUNICATION
Mild access to planar‐chiral ortho‐condensed aromatic ferrocenes
via enantioselective cationic gold(I)‐catalyzed cycloisomerization
of ortho‐alkynylaryl ferrocenes
Received 00th January 20xx,
Accepted 00th January 20xx
Antonio Urbano,* Gloria Hernández‐Torres,# Ana M. del Hoyo,# Alicia Martínez‐Carrión, M.
DOI: 10.1039/x0xx00000x
Carmen Carreño*
www.rsc.org/
An efficient approach to (Rp) planar‐chiral tri‐ and tetracyclic
ortho‐condensed aromatic ferrocenes was developed through the
enantioselective cationic Au(I)‐catalyzed cycloisomerization, in the
presence of bidentate phosphine ligand (R)‐DTBM‐Segphos, from
readily available ortho‐alkynylaryl ferrocenes under very mild
conditions (11 examples, up to 92% yield and 93% ee).
Planar‐chiral ferrocenes are important scaffolds in organic and
organometallic chemistry and have been used in a wide range
of asymmetric reactions as ligands, catalysts, or templates.1
Their preparation in enantiomerically enriched form has been
achieved either by diastereoselective transformation utilizing
stoichiometric homochiral substituents/reagents or by optical
resolution of preformed racemic compounds.2 More recently,
enzymatic3 and non‐enzymatic kinetic resolutions,4 as well as
enantioselective desymmetrizations,5 have emerged as
powerful tools for the synthesis of such homochiral structures.
In spite of the advances reached, their enantioselective
synthesis is still a challenging problem.
The development of versatile methods for synthesizing
chiral‐planar ferrocenes in a catalytic manner would be a
highly efficient approach. In spite of the remarkable progress
in the field of asymmetric catalysis, examples of catalytic
controlling planar‐chirality in ferrocenes had been extremely
rare, until recently.6 Thus, the first enantioselective palladium‐
catalyzed ortho C‐H arylation of a ferrocene directed by amine
groups was reported in 2013, using amino acids as ligands.7
Similar conditions were later described for the
enantioselective ferrocene C‐H bond alkenylation and
acylation.8 Besides palladium catalysis, an iridium catalyst in
the presence of chiral diene ligands was employed for a novel
ferrocene C‐H alkylation directed by isoquinoline groups.9
Scheme 1. Enantioselective intramolecular reactions for the synthesis
of planar-chiral ring-fused ferrocenes.
With respect to the intramolecular version of ferrocene C‐
H bond activation to construct planar‐chiral ring‐fused
ferrocenes (Scheme 1), the carbene C–H insertion of
diazoketone‐tethered ferrocenes, mediated by Cu catalyst in
the presence of a chiral Box ligand, was a pioneering work10
and planar‐chiral cyclic ketone‐fused ferrocenes were thus
prepared (Scheme 1a). More recently, planar‐chiral
indenone11a‐b,e and quinolinone‐fused11c‐d ferrocenes were
obtained in excellent ee (Scheme 1b), through the ferrocene
C–H bond arylation with haloarenes,11a‐d including
halopyridines,11e by using Pd catalysts in the presence of
different chiral phosphines or phosphoramides. Finally, the
synthesis of planar‐chiral benzosiloloferrocenes has been
reported by rhodium‐catalyzed intramolecular ferrocene C‐H
bond silylation12 in the presence of chiral dienes or
biphosphines (Scheme 1c). In all cases, temperatures between
40 and 135 ºC were necessary to perform the enantioselective
Departamento de Química Orgánica (Módulo 01), Facultad de Ciencias,
Universidad Autónoma de Madrid, Cantoblanco, 28049‐Madrid, Spain.
E‐mail: antonio.urbano@uam.es; carmen.carrenno@uam.es
# These authors contributed equally to this work.
Electronic Supplementary Information (ESI) available: Experimental procedures,
characterization data and NMR spectra. Crystal structure determinations of (rac)‐
6a CCDC 1469767, and (Rp)‐6e CCDC 1469768 contain the supplementary
crystallographic data for this paper. For ESI and crystallographic data in CIF or
other electronic format see DOI: 10.1039/c0xx00000x/
This journal is © The Royal Society of Chemistry 2015
Chem. Commun., 2015, 51, 1‐4 | 1
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 2 of 5
COMMUNICATION
Journal Name
transformations.
Albeit
these
successful
examples, obtained the ortho‐condensed aromatic tricyclic ferrocene
View Article Online
20
development of new methodologies for catalytic asymmetric (Rp)‐6a with excellent 92% yield and 91D%OeI:e10{.[1039/C6CC02624A

]
= +932 (c
D
synthesis of planar chiral molecules, with diverse skeletons 0.04, CH2Cl2)}, after 5 h (Table 1, entry 9). At a lower
and under milder conditions is still necessary.
temperature (‒10 ºC, entry 10), similar results were observed,
We now report the first general enantioselective synthesis while the reaction became sluggish.
of planar‐chiral ortho‐condensed aromatic ferrocenes from the
cationic gold(I)‐catalyzed13 intramolecular cycloisomerization
of 2‐alkynylaryl ferrocenes, under very mild conditions
(Scheme 1d), based on the metal‐catalyzed intramolecular
hydroarylation of ortho‐alkynylbiaryls initially developed by
Fürstner14 for the synthesis of phenanthrenes and later applied
for higher helicenes.15 To the best of our knowledge, there is
only one example in the literature describing an
enantioselective version of this type of cycloisomerization.16
Scheme 2. Synthesis of model substrate 5a and metal-catalyzed
cycloisomerizations towards racemic and enantioenriched 6a
.
2‐Alkynylphenylferrocene 5a 17
was readily prepared in only 2 steps (Scheme 2) from Suzuki
coupling of commercially available ferrocene boronic acid (
, chosen as model substrate,
1)
and 2‐bromobenzaldehyde (2a), followed by the Seyferth‐
Gilbert homologation18 of the resulting 2‐formylphenyl
ferrocene (3a),19 using the Ohira‐Bestmann reagent 4 20
.
The access to the racemic ortho‐condensed aromatic
ferrocene (rac)‐6a could be achieved, after many
experimentation using different metal catalysts such as
platinum, gold or indium, from the cycloisomerization of 5a
using 10% mol of PtCl2 in toluene at 100 ºC, after a 6‐endo‐dig
process.14b Under these conditions, model substrate 5a
afforded tricyclic aromatic ferrocene (rac)‐6a in practically
quantitative yield, after celite filtration. The tricyclic ortho‐
condensed aromatic structure of ferrocene (rac)‐6a could be
demonstrated after an X‐ray diffraction study (Scheme 2).
Our initial attempts for the enantioselective version of this
cycloisomerization using chiral platinum catalysis21 were quite
disappointing, even in terms of lack of reactivity, and we
decided to move to the more developed chiral cationic gold(I)
catalysis13 (Scheme 2, Table 1). We first tried the
enantioselective Au(I)‐catalyzed cycloisomerization of model
substrate 5a using 10% of commercially available bidentate
phosphine ligand (R)‐DTBM‐Segphos (L1) in the presence of
20% AgSbF6, in dichloroethane (DCE) as solvent (entry 1).
Under these conditions, we could obtain, after one hour at
room temperature, ortho‐condensed aromatic ferrocene (Rp)‐
6a in a satisfactory 70% yield but a very poor 15% ee.
Delightedly, when the same reaction was performed in
toluene as solvent (entry 2), the enantioselective
cycloisomerization process furnished, after 1 h at rt and
filtration over neutralized silica gel, planar‐chiral tricyclic
aromatic ferrocene (Rp)‐6a in a good 86% yield and a promising
83% ee. The use of other commercially available bidentate
phosphine ligands (entries 3‐6) such as Segphos (L2), DM‐
Segphos (L3), BINAP (L4) or DTBM‐MeOBiphep (L5) afforded,
under similar conditions, good yields (72‐85%) of (Rp)‐6a albeit
with poor enantioselectivities (5‐37% ee). Next, the effect of
the counterion was investigated (Table 1, entries 7 and 8) and
silver triflate and silver tetrafluorborate as a halide scavenger
gave comparable results in terms of chemical yield to that
using AgSbF6 (entry 2), but slightly lower related to the optical
purity of (Rp)‐6a. Finally, lowering the temperature to 0 ºC, we
Table 1. Reaction conditions optimization.
Entry
L*
AgX
Solvent
T
t
(h)
Yield
(%)
ee
(ºC)
(%)[a]
1
2
L1 AgSbF6
DCE
rt
rt
1
1
70
86
81
72
85
85
79
92
92
90
15
83
10
37
5
L1 AgSbF6 Toluene
L2 AgSbF6 Toluene
L3 AgSbF6 Toluene
L4 AgSbF6 Toluene
L5 AgSbF6 Toluene
3
rt
1
4
rt
1
5
rt
2
6
rt
1
16
77
80
91
91
7
L1
L1
AgOTf
AgBF4
Toluene
Toluene
rt
1
8
rt
1
9
L1 AgSbF6 Toluene
L1 AgSbF6 Toluene
0
5
10
‒10
20
[a] Determined by chiral HPLC analysis (see ESI)
The (Rp) absolute configuration of 6a was ascertained after
the chemical correlation shown in Scheme 3, starting from
planar‐chiral p‐tolylsulfinyl ferrocenyl boronic acid (SS,Sp)‐7,
whose absolute configuration is perfectly known.22 Thus, the
Suzuki coupling between p‐tolylsulfinyl ferrocenyl boronic acid
2 Chem. Commun., 2015, 51, 1‐4
This journal is © The Royal Society of Chemistry 2015
Please do not adjust margins

Page 3 of 5
ChemComm
Please do not adjust margins
Journal Name
(SS,Sp)‐ (>98% ee) and iodobenzene (
COMMUNICATION
7
8
), in the presence of the 8‐fluoro‐substituted derivative (Rp)‐6c commented before,
View Article Online
PdCl2(dppf) and NaOH,23 afforded phenyl‐substituted it was possible to synthesize planar‐chiral aromatic ferrocenes
DOI: 10.1039/C6CC02624A
ferrocene (SS,Sp)‐
9
with 79% yield (Scheme 3). Next, the (Rp)‐6f
–h, having fluorine substituents at all positions of the
sulfoxide‐lithium exchange on (SS,Sp)‐
9
effected by tert‐BuLi, external aromatic ring of the tricyclic moiety, with excellent
followed by the addition of N,N‐dimethyl formamide as optical purities (89‐93% ee) for the 7‐ and 9‐substituted
formylating agent,24 yielded a 64% of 1‐formyl‐2‐phenyl derivatives (Rp)‐6f and (Rp)‐6g, and moderate ee (68%) for the
ferrocene (Sp)‐10 25
.
The subsequent transformation of the 6‐fluoro‐substituted
ferrocene
(Rp)‐6h
.
This
lower
formyl group of (Sp)‐10 into a triple bond was carried out using enantioselectivity could be probably due to the close proximity
the two‐step Corey‐Fuchs procedure.26 Thus, reaction of (Sp)‐ of the fluorine atom, ortho to the reactive triple bond, in the
10 with CBr4 and PPh3 afforded the corresponding starting material 5h
.
Finally, two more examples of
bearing
= ‒434 (c 0.08, two oxygenated or fluorine atoms at the 7 and 8 positions
dibromoalkene which was treated with n‐BuLi furnishing 2‐ disubstituted tricyclic aromatic ferrocenes (Rp)‐6i
–j
20
alkynyl‐1‐phenyl ferrocene (Rp)‐11 {[]
D
CH2Cl2)}, in 60% yield. Finally, the PtCl2‐catalyzed were obtained, showing excellent (93% ee for 6i) and good
cycloisomerization of (Rp)‐11 in toluene at 100 ºC gave rise to optical purities (87% ee for 6j), respectively.†
the ortho‐condensed aromatic tricyclic ferrocene (Rp)‐6a in
20
almost quantitative yield and >98% ee {[

]
D = +1037 (c 0.013,
R
R
8
(R)-DTBM-Segphos(AuCl)2 (10%)
9
CH2Cl2)}, identical in all aspects to derivative obtained in the
enantioselective Au(I)‐catalyzed process shown in Scheme 2.
7
AgSbF6 (20%)
6
toluene, 0 ºC, 3-15 h
Fe
Fe
(Rp)-6b-j
5b-j
74-92%
Me
F
8
OMe
8
8
Fe
Fe
Fe
(Rp)-6c, 85%, 92% ee
[ ]D20 = +3260
(Rp)-6d, 84%, 91% ee
[ ]D20 = +980
(Rp)-
6b, 83%, 82% ee
[ ]D20 = +2750
(c 0.08, CH2Cl2)
(c 0.012, CH2Cl2)
(c 0.007, CH2Cl2)
F
9
7
F
7
OMe
Fe
Fe
Fe
(Rp)-6f, 82%, 89% ee
[ ]D20 = +432
(Rp)-6g, 74%, 93% ee
[ ]D20 = +2710
(c 0.07, CH2Cl2)
F
(Rp)-6e, 90%, 81% ee
[ ]D20 = +1545
(c 0.032, CH2Cl2)
(c 0.016, CH2Cl2)
O
8
Scheme 3. Synthesis of (Rp)‐6a from known (SS,Sp)‐7.
8
7
7
O
F
6
F
Having established the absolute configuration of (Rp)‐6a
and the optimal catalytic conditions for the enantioselective
cycloisomerization of 5a shown in Table 1, entry 9, (R)‐DTBM‐
Segphos(AuCl)2 (10% mol) associated with the silver salt
AgSbF6 (20% mol) in toluene at 0 ºC, the scope of the
methodology was ascertained by subjecting a range of
Fe
Fe
Fe
(Rp)-6h, 79%, 68% ee
[ ]D20 = +660
(Rp)-6i, 85%, 93% ee
[ ]D20 = +2444
(Rp)-6j, 83%, 87% ee
[ ]D20 = +2774
(c 0.055, CH2Cl2)
(c 0.037, CH2Cl2)
(c 0.042, CH2Cl2)
diversely substituted 2‐alkynylarylferrocenes 5b–j to the best
Table 2. Scope of the gold‐catalyzed cycloisomerization.
reaction parameters. As summarized in Table 2, various
substituents on different positions of the phenyl ring,
regardless of their electronic nature, were well tolerated
Having demonstrated the scope of the enantioselective Au‐
catalyzed cycloisomerization process for the synthesis of
enantioenriched differently substituted tricyclic aromatic
affording tricyclic aromatic ferrocenes (Rp)‐6b
excellent yields and enantiomeric excesses. Thus, three planar‐
chiral ferrocenyl derivatives (Rp)‐6b bearing –OMe (82% ee),
–j with good to
ferrocenes 6a‐j, we were interested in extending the
–
d
methodology to the construction of a planar‐chiral tetracyclic
aromatic ferrocene such as (Rp)‐6k, in a three‐step sequence as
depicted in Scheme 4. Thus, the Suzuki coupling between
–F (92% ee) and –Me (91% ee) groups at the 8 position could
be obtained in good to excellent enantiomeric purities,
showing high values of their optical rotations. We also
commercially available ferrocene boronic acid (1) and 1‐
prepared the 7‐methoxy‐substituted aromatic ferrocene (Rp)‐
bromo‐2‐naphthaldehyde (2a) afforded, in 79% yield, the
corresponding naphthyl ferrocene 3k, whose homologation
20
6e, which was obtained with a good 81% of ee {[

]
D = +1545
(c 0.016, CH2Cl2)} and whose absolute configuration could be
demonstrated after a X‐ray diffraction study (see ESI). Besides
with the Ohira‐Bestmann reagent
4 gave rise to the alkynyl
naphthyl ferrocene 5k
,
in 61% yield. Finally, the
This journal is © The Royal Society of Chemistry 2015
Chem. Commun., 2015, 51, 1‐4 | 3
Please do not adjust margins

Please do not adjust margins
ChemComm
Page 4 of 5
COMMUNICATION
Journal Name
Arae, K. Nakajima, T. Takahashi, M. Ogasawara, OVrgieawnAormticeletaOlnlilcinse,
enantioselective cycloisomerization of 5k in the presence of
10% mol of (R)‐DTBM‐Segphos(AuCl)2 and 20% mol of AgSbF6
in toluene at 0 ºC for 15 h, furnished tetracyclic ortho‐
2015, 34, 1197. (c) K. Akagawa, M. Akiyama, K. Kudo, Eur. J. Org.
DOI: 10.1039/C6CC02624A
Chem., 2015, 3894.
Recent reviews: (a) S. Arae, M. Ogasawara, Tetrahedron Lett., 2015,
56, 1751. (b) L. A. López, E. López, Dalton Trans., 2015, 44, 10128. (c)
D.‐Y. Zhu, P. Chen, J.‐B. Xia, Chem. Cat. Chem., 2016, 8, 68.
(a) D. W. Gao, Y. C. Shi, Q. Gu, Z. L. Zhao, S. L. You, J. Am. Chem. Soc.,
2013, 135, 86. (b) Y. C. Shi, R. F. Yang, D. W. Gao, S. L. You, Beilstein
6
7
condensed aromatic ferrocene (Rp)‐6k, in excellent 88% yield
20
and 93% ee {[

]
D = +1934 (c 0.017, CH2Cl2)}.
J. Org. Chem., 2013, 9, 1891. (c) Gao, D. W.; Gu, Q.; You, S. L. J. Am.
Chem. Soc., 2016, 138, 2544. Very recent example using Rh(III)
catalysis: (d) S. B. Wang, J. Zheng, S. L. You, Organometallics, 2016,
DOI: 10.1021/acs.organomet.6b00020.
8
9
(a) C. Pi, Y. Li, X. Cui, H. Zhang, Y. Han, Y. Wu, Chem. Sci., 2013, 4,
2675. (b) C. Pi, X. Cui, X. Liu, M. Guo, H. Zhang, Y. Wu, Org. Lett.,
2014, 16, 5164.
T. Shibata, T. Shizuno, Angew. Chem., Int. Ed., 2014, 53, 5410.
10 S. Siegel, H.‐G. Schmalz, Angew. Chem., Int. Ed. Engl., 1997, 36, 2456.
11 (a) D. W. Gao, Q. Yin, Q. Gu, S. L. You, J. Am. Chem. Soc., 2014, 136
,
4841. (b) R. Deng, Y. Huang, X. Ma, G. Li, R. Zhu, B. Wang, Y. B. Kang,
Z. Gu, J. Am. Chem. Soc., 2014, 136, 4472. (c) L. Liu, A. A. Zhang, R. J.
Zhao, F. Li, T. J. Meng, N. Ishida, M. Murakami, W. X. Zhao, Org. Lett.,
2014, 16, 5336. (d) X. Ma, Z. Gu, RSC Adv., 2014, 4, 36241. (e) D.‐W.
Gao, C. Zheng, Q. Gu, S.‐L. You, Organometallics, 2015, 34, 4618.
12 (a) T. Shibata, T. Shizuno, T. Sasaki, Chem. Commun., 2015, 51, 7802.
(b) Q.‐W. Zhang, K. An, L.‐C. Liu, Y. Yue, W. He, Angew. Chem., Int.
Ed., 2015, 54, 6918. (c) M. Murai, K. Matsumoto, Y. Takeuchi, K.
Takai, Org. Lett., 2015, 17, 3102.
13 Recent reviews: (a) W. Zi, F. D. Toste, Chem. Soc. Rev., 2016, DOI:
10.1039/C5CS00929D. (b) M. Brill, S. P. Nolan, Top. Organomet.
Chem., 2016, DOI: 10.1007/3418_2015_142. (c) B. Ranieri, I.
Escofeta, A. M. Echavarren, Org. Biomol. Chem., 2015, 13, 7103. (d)
Scheme 4. Synthesis of tetracyclic ferrocene (Rp)‐6k
.
In summary, we have developed a highly efficient synthesis
of planar‐chiral aromatic ferrocenes by enantioselective Au(I)‐
catalyzed C−H acꢀvaꢀon, under very mild reacꢀon condiꢀons,
of readily available ortho‐alkynylaryl ferrocenes, prepared in
only two steps from commercially available ferrocenyl boronic
acid and 2‐bromobenzaldehydes. This is the first example of
the preparation of homochiral 1,2‐disubstituted ferrocenes in
optically enriched form using gold catalysis and may offer a
short, practical and versatile route to functionalized planar‐
chiral metallocenes. Studies on the mechanistic aspects and
applications of these structurally new ferrocenes in organic
synthesis and catalysis are underway in our laboratories.
We thank MICINN (Grants CTQ2011‐24783 and CTQ2014‐
53894‐R) for financial support.
S. M. Inamdar, A. Konala, N. T. Patil, Chem. Commun., 2014, 50
15124. (e) A. D. Lackner, F. D. Toste, Acc. Chem. Res., 2014, 47, 889.
14 V. Mamane, P. Hannen, A. Fürstner, Chem. Eur. J., 2004, 10, 4556.
,
15 Selected recent examples: (a) M. W. van der Meijden, E. Gelens, N.
Murillo Quiros, J. D. Fuhr, J. Esteban Gayone, H. Ascolani, K. Wurst,
M. Lingenfelder, R. M. Kellogg, Chem. Eur. J., 2016, 22, 1484. (b) Y.
Yamamoto, K. Matsui, M. Shibuya, Chem. Eur. J., 2015, 21, 7245. (c)
J. Liu, B.‐W. Li, Y.‐Z. Tan, A. Giannakopoulos, C. Sanchez‐Sanchez, D.
Beljonne, P. Ruffieux, R. Fasel, X. Feng, K. Mullen, J. Am. Chem. Soc.,
2015, 137, 6097. (d) K. Mitsudo, H. Sato, A. Yamasaki, N. Kamimoto,
J. Goto, H. Mandai, S. Suga, Org. Lett., 2015, 17, 4858.
16 K. Nakamura, S. Furumi, M. Takeuchi, T. Shibuya, K. Tanaka, J. Am.
Chem. Soc., 2014, 136, 5555.
17 M. R. Buchmeiser, N. Schuler, G. Kaltenhauser, K.‐H. Ongania, I.
Lagoja, K. Wurst, H. Schottenberger, Macromolecules, 1998, 31
3175.
,
Notes and references
18 (a) D. Seyferth, R. S. Marmor, P. Hilbert, J. Org. Chem., 1971, 36
1379. (b) J. C. Gilbert, U. Weerasooriya, J. Org. Chem., 1982, 47
1837.
19 B. Long, S. Liang, D. Xin, Y. Yang, J. Xiang, Eur. J. Med. Chem., 2009,
44, 2572.
,
,
†
The gold(I)‐catalyzed cycloisomerization of an alkynyl ferrocenyl
tiophene afforded the corresponding methyl ketone after hydration of
the triple bond, whereas no reaction was observed in the case of a
pyridine‐substituted derivative.
Selected recent reviews: (a) Chiral Ferrocenes in Asymmetric
Catalysis, eds. L.‐X. Dai, X.‐L. Hou, Wiley‐VCH, Weinheim, 2010. (b) T.
1
20 (a) S. Müller, B. Liepold, G. J. Roth, H. J. Bestmann, Synlett, 1996,
521. (b) S. Ohira, Synth. Commun., 1989, 19, 561.
Noel, J. Van der Eycken, Green Process. Synth., 2013, 2, 297. (c) M.
21 (a) A. Pradal, S. Gladiali, V. Michelet, P. Y. Toullec, Chem. Eur. J.,
2014, 20, 7128. (b) A. Marinetti, H. Jullien, A. Voituriez, Chem. Soc.
Rev., 2012, 41, 4884. (c) I. D. G. Watson, F. D. Toste, Chem. Sci.,
Drusan, R. Sebesta, Tetrahedron, 2014, 70, 759. (d) N. A. Butt, D. Liu,
W. Zhang, Synlett, 2014, 25, 615. (e) S. Toma, J. Csizmadiova, M.
Meciarova, R. Sebesta, Dalton Trans., 2014, 43, 16557.
2012, 3, 2899.
2
3
4
Review: D. Schaarschmidt, H. Lang, Organometallics, 2013, 32, 5668.
Review: A. N. Alba, R. Rios, Molecules 2009, 14, 4747.
22 (a) J. F. Jensen, I. Sotofte, H. O. Sorensen, M. Johannsen, J. Org.
Chem., 2003, 68, 1258. (b) J. G. Seitzberg, C. Dissing, I. Sotofte, P.‐O.
Norrby, M. Johannsen, J. Org. Chem., 2005, 70, 8332.
Selected recent examples: (a) A. Latorre, A. Urbano, M. C. Carreño,
Chem. Commun., 2011, 47, 8103. (b) M. Ogasawara, S. Arae, S.
Watanabe, K. Nakajima, T. Takahashi, Chem. Eur. J., 2013, 19, 4151.
(c) M. Akiyama, K. Akagawa, H. Seinob, K. Kudo, Chem. Commun.,
2014, 50, 7893. (d) K. Akagawa, N. Nishi, I. Yoshikawa, K. Kudo, Eur.
J. Org. Chem., 2015, 5055. (e) R. Liu, G. Zhou, T. H. Hall, G. J.
Clarkson, M. Wills, W. Chen, Adv. Synth. Catal., 2015, 357, 3453.
Selected recent examples: (a) P. Buchgraber, A. Mercier, W. C. Yeo,
C. Besnard, E. P. Kündig, Organometallics, 2011, 30, 6303. (b) S.
23 J. F. Jensen, M. Johannsen, Org. Lett., 2003, 5, 3025.
24 (a) H.‐L. Zhang, X.‐L. Hou, L.‐X. Dai, Z.‐B. Luo, Tetrahedron:
Asymmetry, 2007, 18, 224. (b) C. Pichon, B. Odell, J. M. Brown,
Chem. Commun., 2004, 598.
25 H. Lehner, K. Schlögl, Monatsh. Chem., 1970, 101, 895.
26 E. J. Corey, P. L. Fuchs, Tetrahedron Lett., 1972, 13, 3769.
5
4 Chem. Commun., 2015, 51, 1‐4
This journal is © The Royal Society of Chemistry 2015
Please do not adjust margins

Page 5 of 5
ChemComm
Please do not adjust margins
Journal Name
COMMUNICATION
View Article Online
DOI: 10.1039/C6CC02624A
TOC Graphic
An enantioselective cationic gold(I)-catalyzed cycloisomerization of
aquiral 2-alkynylaryl ferrocenes provides differently substituted tricyclic
and tetracyclic (Rp) planar-chiral ortho-condensed aromatic ferrocenes
in high yield and enantioselectivity from an efficient intramolecular
hydroarylation.
This journal is © The Royal Society of Chemistry 2015
Chem. Commun., 2015, 51, 1‐4 | 5
Please do not adjust margins