Switchable Stereoselectivity in Bromoaminocyclization of Olefins: Using Br?nsted Acids of Anionic Chiral Cobalt(III) Complexes

Article abstract of DOI:10.1002/anie.201705066

Br?nsted acids of anionic chiral Co^III complexes act as bifunctional phase-transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral Co^III-templated Br?nsted ac

Full text of DOI:10.1002/anie.201705066

A Journal of the Gesellschaft Deutscher Chemiker
Angewandte
Chemie
International Edition
www.angewandte.org
Accepted Article
Title: Switchable Stereoselectivity in Bromoaminocyclization of Olefins
Catalyzed by Brønsted Acids of Anionic Chiral CoIII Complexes
Authors: Liuzhu Gong, Hua-Jie Jiang, kun Liu, Jie Yu, and Ling Zhang
This manuscript has been accepted after peer review and appears as an
Accepted Article online prior to editing, proofing, and formal publication
of the final Version of Record (VoR). This work is currently citable by
using the Digital Object Identifier (DOI) given below. The VoR will be
published online in Early View as soon as possible and may be different
to this Accepted Article as a result of editing. Readers should obtain
the VoR from the journal website shown below when it is published
to ensure accuracy of information. The authors are responsible for the
content of this Accepted Article.
To be cited as: Angew. Chem. Int. Ed. 10.1002/anie.201705066
Angew. Chem. 10.1002/ange.201705066
Link to VoR: http://dx.doi.org/10.1002/anie.201705066
http://dx.doi.org/10.1002/ange.201705066

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
Switchable Stereoselectivity in Bromoaminocyclization of Olefins
Catalyzed by Brønsted Acids of Anionic Chiral CoIII Complexes
Hua-Jie Jiang,[a] Kun Liu,[b] Jie Yu,*[b] Ling Zhang[a] and Liu-Zhu Gong*[a]
Abstract: Brønsted acids of anionic chiral CoIII complexes have
been first found to act as bifunctional phase-transfer catalysts to
shuttle the substrates across interface and control stereoselectivity.
The diastereomeric chiral CoIII-templated Brønsted acids with the
catalysis would be essentially important in synthetic organic
chemistry. Herein, we will describe the Λ- and Δ-diastereomeric
CoIII-complexes acting as “pseudo-enantiomers” to render the
asymmetric reaction to give opposite enantiomers, and will
demonstrate the versatility of the chiral CoIII-templated Brønsted
same chiral ligands enabled
a
switchably enantioselective
bromoamino-cyclization of olefins to afford two opposite enantiomers
of 2-substituted pyrrolidines with high enantioselectivities (up to 99:1
e.r.), respectively.
acids
as
highly efficient catalysts for
asymmetric
bromoaminocyclization of olefins (Scheme 1).
Chiral anions-mediated catalysis, including “asymmetric
counteranion-directed catalysis” and “chiral anion phase-transfer
catalysis”, has steadily received increasing research interest,[1]
while the conventional strategy for the establishment of their
chirality mostly relies on the chiral organic molecular anion
catalysts, such as borane anions,[2a-2b] phosphate anions[2c-2g]
and anion-bonding (thio)ureas.[2h-2i] However, the potential of
stereochemically stable octahedral chiral metal-complex
counteranions, in which the metal center does not serve as a
catalytic center to directly activate substrate by coordination but
Scheme 1. The Λ- and Δ-diastereomeric CoIII-complexes used for the inter-
molecular bromoaminocyclization.
just offers
a
rigid framework and the environment of
centrochirality, has much less been recognized in asymmetric
catalysis.[3] Belokon and coworkers have introduced a series of
salicylaldehyde derived chiral CoIII-complex counteranions,
which are capable of affording a few C-C bond formation
reactions, but with low to moderate enantioselectivities.[4] The
most severe limitation of these CoIII-complexes turns out to be
the stereocontrolled synthesis of defined meridional
stereoisomers.[5] In addition, in the cases concerning chiral
metal-complexes (RuII, CoIII) with chiral ligands,[4,6] the nature of
asymmetric induction has not been identified for the moment.
We very recently demonstrated that sodium salts of anionic
chiral CoIII complexes (Scheme 1, Λ-1c) were excellent catalysts
of asymmetric Povarov reaction of simple 2-azadienes, wherein
the weakly bonding nature of chiral ion-pair was considered to
permit the alkali cation to work as a Lewis acid for the activation
of imine functionality.[7] This feature is distinct from the traditional
metal complexes wherein the positive charge on the metal is
compensated by ligand coordination and thus would be able to
make either acid or salt form of anionic chiral metal-complexes
hold unique privilege in asymmetric catalysis. Therefore, the
creation of structurally diverse range of new chiral metal-
complexes and disinterment of their applications in asymmetric
After the diastereoselective synthesis of sodium salts and
Brønsted acids of anionic chiral CoIII complexes was achieved,[8]
we chose bromoaminocyclization of olefins as a benchmark
reaction,[9-10] which has received increasing interest as the
corresponding products (e.g., pyrrolidines) are core structural
element in biological pharmaceutical molecules, and organo-
catalysts[11] and thereby are of high synthetic significance. The
reaction of γ-amino-alkene 2a with N-bromosuccinimide (NBS)
was initially examined in the presence of 5 mol % of sodium
salts of anionic chiral CoIII complexes, Λ-(S,S)-1a-1c. As
anticipated, the desired reaction underwent smoothly to give 2-
substituted pyrrolidine 3a in good yields, but with low levels of
enantioselectivity (Table 1, entries 1-3). Interestingly, the metal-
templated Brønsted acids exhibited much higher catalytic activity
and stereoselectivity than corresponding salts (entries 4-6). In
particular, the Brønsted acid Λ-(S,S)-1e was able to provide 3a
with a 99% yield and 98:2 e.r. (entry 5). As anticipated, Δ-(S,S)-
1e, the diastereomer of Λ-(S,S)-1e, indeed enabled the reaction
to give the ent-3a in 94.5:5.5 e.r. (entry 6). The screening of
other reaction parameters including additives, temperature and
solvents suggested that the performance of the reaction in a
nonpolar solvent gave higher enantioselectivity and 5 Å M.S.
turned out to be the best additive while the reaction temperature
exerted little effect on the stereoselectivity (entries 7-13).
Under the optimized conditions, the generality of the
enantioselective bromoaminocyclization for the N-protecting
group of alkene 2 was then explored. The alternation of sulfonyl-
protected γ-amino-alkenes 2 was nicely tolerated, affording N-
protected 2-substituted pyrrolidines 3 in up to 99% yield and
98:2 e.r. (Table 2, entries 1-9). The electronic feature and
substitution pattern of the aryl group did not exert significant
influence on the stereoselectivities, and the highest enantiomeric
ratios were obtained for products 3a, 3e, 3f, and 3h (entries 1, 5,
6 and 8). However, the introduction of 2-nitro group to the N-
[a]
H.-J. Jiang, L. Zhang, Prof. Dr. L.-Z. Gong
Hefei National Laboratory for Physical Sciences at the Microscale
and Department of Chemistry
University of Science and Technology of China
Hefei, 230026, China
E-mail: gonglz@ustc.edu.cn
[b]
K. Liu, Prof. Dr. J. Yu
State Key Laboratory of Tea Plant Biology and Utilization and
Department of Applied Chemistry
Anhui Agricultural University
Hefei, 230036, China
E-mail: jieyu@ahau.edu.cn
Supporting information for this article is given via a link at the end of
the document.
This article is protected by copyright. All rights reserved.

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
phenylsulfonyl led to
enantioselectivity (entry 7).
a
much diminished yield and
the case of a trisubstituted olefin (3l). The geometry of carbon-
carbon double bond greatly influences the stereoselectivity, as
indicated by the fact that
a
tremendously higher
Table 1. Optimization of the enantioselective bromoaminocyclization of 2a.[a]
enantioselectivity (99:1 e.r.) was observed for cis-γ-amino-
alkene (3n) than trans-γ-amino-alkene (86:14 e.r.) (3m). A
variety of cis-γ-amino-alkenes were proven to be excellent
substrates in the bromoaminocyclization, to provide desired
heterocycles in good yields and with up to 99:1 e.r. (3n-3r). α-
Dialkyl-β-diphenyl-γ-amino-alkene and β-diaryl-γ-amino-alkenes
could also undergo the asymmetric bromoaminocyclization
smoothly to furnish the desired products in high
enenatioselectivities (3s-3v). Although the α- and β-
unsubstituted γ-amino-alkene underwent a clean reaction, a
moderate enantioselectivity was offered (3w). To our delight, the
halofunctionalization of allenes, which has relatively been
unexplored,[12] could cleanly proceed catalyzed by the metal-
templated Brønsted acid Λ-(S,S)-1e, providing the vinyl bromide
intermediate in excellent yield and with 97:3 e.r. (3x). The
absolute configurations of 3o and 3x were assigned by single-
crystal X-ray diffraction analysis.[13]
entry
1
1
yield [%][b]
53
e.r.[c]
67:33
Λ-(S,S)-1a
2
3
Λ-(S,S)-1b
Λ-(S,S)-1c
Λ-(S,S)-1d
Λ-(S,S)-1e
Δ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
Λ-(S,S)-1e
54
43
99
99
98
94
91
84
72
97
98
87
47.5:52.5
53:47
4
77.5:22.5
98:2
5
6
5.5:94.5
51:49
7[d]
8[e]
9[f]
10[g]
11[h]
12[i]
13[j]
90:10
95:5
97.5:2.5
95:5
Table 3. Substrate scope of switchably enantioselective bromoaminocyclization.[a]
97.5:2.5
96:4
[a] Unless otherwise noted, the reaction was performed with 2a (0.1 mmol),
NBS (0.12 mmol), catalyst 1 (0.005 mmol) and 5 Å M. S. (100 mg) in toluene (2
°
mL) at -20 C for 10 h. [b] Yield of isolated product. [c] Determined by HPLC
analysis on a chiral stationary phase. [d] CH2Cl2 was used. [e] CCl4 was used.
[f] 3 Å M. S. was used. [g] 4 Å M. S. was used. [h] The reaction was carried out
at 25 °C for 90 minutes. [i] The reaction was carried out at 0 °C. [j] The reaction
was carried out at -40 °C. M. S. = molecular sieves.
Table 2. Variation of the N-protecting group.[a]
entry
3
Ar
yield (%)[b]
e.r.[c]
98:2
1
2
3
4
5
6
7
8
9
3a
3b
3c
3d
3e
3f
Ph
99
99
99
99
99
99
56
99
99
4-MeC6H4
2,4,6-Me3C6H2
4-MeOC6H4
4-NO2C6H4
3-NO2C6H4
2-NO2C6H4
1-naphthyl
2-naphthyl
96:4
93.5:6.5
93.5:6.5
98:2
98:2
3g
3h
3i
86:14
98:2
95.5:4.5
[a] Unless otherwise noted, the reaction was performed with 2 (0.1 mmol), NBS
(0.12 mmol), catalyst Λ-(S,S)-1e (0.005 mmol) and 5 Å M. S. (100 mg) in toluene
(2 mL) at -20 C for 10 h. [b] Yield of isolated product. [c] Determined by HPLC
[a] Unless otherwise noted, the reaction was performed with 2 (0.1 mmol), NBS
(0.12 mmol), catalyst 1e (0.005 mmol) and 5 Å M. S. (100 mg) in toluene (2 mL) at
-20 °C for 10 h. [b] Yield of isolated product. [c] Determined by HPLC analysis on a
chiral stationary phase. p-Ns = p-nitrophenyl sulfonyl; m-Ns = m-nitrophenyl
sulfonyl.
°
analysis on a chiral stationary phase.
The capacity of the reaction catalyzed by Λ-(S,S)-1e to
tolerate the substituent on the alkene moiety of 2 was next
investigated (Table 3). The γ-amino-alkene bearing either a
methyl or phenyl group at C2, delivered the corresponding 2-
substituted pyrrolidine with a quaternary stereocenter in a high
enantiomeric ratio of 93.5:6.5 (Table 3, 3j-3k). Significantly, an
excellent enantioselectivity (98.5:1.5 e.r.) was also obtained in
The Δ-(S,S)-1e was also identified to be an alternative catalyst
for the titled reaction, leading to the generation of desired
products with opposite configurations in up to 96:4 e.r. (Table 3,
3a’, 3e’, 3f’, 3l’, 3n’, 3x’). In these cases, the metal-centered
chirality in the Brønsted acids of anionic chiral CoIII complexes
This article is protected by copyright. All rights reserved.

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
determined the stereochemistry and the chirality of L-amino acid
moiety has little effect on the asymmetric induction. As such,
both enantiomers of 2-substituted pyrrolidines could be
accessed via the bromoaminocyclization, respectively catalyzed
by the diastereomers of chiral CoIII complexes [Δ-(S,S)-1e and
Λ-(S,S)-1e] without need to alter the chirality of L-valine, which is
seemingly “one stone kills two birds”. Such a unique feature
makes chiral metal-templated Brønsted acids of this type
superior to traditional chiral metal complex catalysts which
basically rely on the alternation of the configuration of chiral
ligands to switch the configuration of products.
Brønsted acid functions like
a
bifunctional phase-transfer
catalyst[1,19] to shuttle the less soluble brominating reagent to
reaction solution and also control the stereochemistry. Moreover,
based on the configuration of 3o, transition states to explain the
observed stereochemistry were proposed (Scheme 3).[10a-10b]
The C-C double bond of alkene 2 attacks the bromiranium ion of
the bifunctional chiral ion pair 12 and concertedly, the
nucleophilicity of the sulfonamide group would be enhanced via
hydrogen bonding interaction with anion complex as shown in
transition states TS-I [with Λ-(S,S)-12] and TS-II [with Δ-(S,S)-
12], respectively. The bromoaminocyclization could favorably
occur on the Re-face of the cis-olefin in TS-I, as the Si-face
might be disfavored due to the steric repulsion between the tert-
butyl substituent of the Schiff base and the phenyl as well as the
sulfonamide group (R’) of the substrate (TS-III). The lower e.r.
for trans-olefins than cis-olefins (Table 3, 3m vs 3n) could be
attributed to the slight interactions between the R group and the
phenyl of the substrate and the two tert-butyl substituents of the
Schiff base (TS-IV).
Scheme 2. Synthetic versatility of the product.
Importantly, the asymmetric bromocyclization catalyzed by
Brønsted acids of anionic chiral CoIII complexes could be scaled
up. Even the presence of 1 mol% Λ-1e was sufficient to render a
gram-scale reaction to give 3e in 99% yield and with 98:2 e.r.
(Scheme 2a). The resultant products can be easily converted
into some other synthetically useful pyrrolidine derivatives.[14] For
instance, a substitution reaction of bromide 3e with NaN3
afforded an azide 4 with maintained enantioselectivity of 98:2
e.r., which can be obtained in optically pure form after a single
recrystallization (Scheme 2b).[15] The removal of the protecting
group from the compound 6 with thiophenol generated an amine
5, which was treated with Boc2O to furnish 6. The hydrogenation
of the azide group of 6 over Pd/C, followed by a condensation
reaction with 3,5-bis(trifluoromethyl)phenyl isothiocyanate and
deprotection, provided 4,4-diphenyl pyrrolidine-thiourea 7 in an
overall 63% yield over three steps. As a showcase, the
bifunctional molecule 7 was applied to catalyze asymmetric
Michael addition[16] of cyclohexanone 8 to nitroolefins 9, giving
the desired adduct 10 in 3:1 d.r. and 90:10 e.r. (Scheme 2c).[17]
Scheme 3. Proposed mechanism and transition states.
In conclusion, Brønsted acids of anionic chiral CoIII complexes
have been revealed to be able to catalyze
a highly
enantioselective bromoaminocyclization of γ-amino-alkenes with
NBS. The employment of meridional diastereomers [Δ-(S,S)-
and Λ-(S,S)-] of chiral CoIII-templated Brønsted acids accessed
from easily available chiral source allows for the stereoselective
formation of two enantiomers of 2-substituted pyrrolidines in high
optical purity, respectively. The process could proceed with
maintained stereoselectivity at gram scale even in the presence
of 1 mol% catalyst. More importantly, it turned out that the chiral
metal-complex acted as a phase-transfer catalyst to shuttle the
substrates across interface and to control stereoselectivity.
These findings not only showed the great potential of the anionic
chiral CoIII complexes in asymmetric catalysis, but will be able to
inspire the future development of anionic chiral CoIII complexes
as either of Brønsted acid, Lewis acid, or alternative chiral
phase-transfer catalysts for the creation of asymmetric
transformations.
Based on the kinetic data, 1H-NMR analysis, NLE and MS
experiment,[18] a plausible reaction mechanism was proposed
(Scheme 3). The Brønsted acid might first undergo an exchange
reaction with NBS to generate a covalent ‘CO2Br species’ 11
and succinimide in nonpolar media. The resonant equilibrium of
unstable 11 leads to the formation of the tight ion pair 12. The
chiral ion pair 12 is highly soluble in the nonpolar solvent and
thereby undergoes the asymmetric bromoaminocyclization with
the olefin substrate 2 to generate the product 3 and regenerate
the Brønsted acid 1. In this case, chiral CoIII complex-templated
Experimental Section
A 10-mL oven-dried vial was charged with γ-amino-alkene 2 (0.10 mmol),
catalyst 1e (0.005 mmol), activated 5 Å molecular sieves (100 mg) and
This article is protected by copyright. All rights reserved.

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
distilled toluene (2 mL) at room temperature. The mixture was cooled to -
20 ºC and stirred for 15 min. The NBS (0.12 mmol) was added and the
resulting solution was stirred vigorously until the reaction was complete
(monitored by TLC). The reaction was then quenched with pre-cooled
NEt3 (-20 ºC, 1.0 mmol) and saturated aqueous Na2S2O3 (0.2 mL). The
mixture was purified by flash column chromatography (silica gel, petrol
ether/EtOAc = 10:1) to give the enantioenriched pyrrolidine derivatives 3.
[6]
For the chiral RuII complexes employing chiral ligands developed by
Ohkuma’s group, see: a) N. Kurono, K. Arai, M. Uemura, T. Ohkuma,
Angew. Chem. 2008, 120, 6745; Angew. Chem. Int. Ed. 2008, 47, 6643;
b) N. Kurono, M. Uemura, T. Ohkuma, Eur. J. Org. Chem. 2010, 1455;
c) N. Kurono, T. Yoshikawa, M. Yamasaki, T. Ohkuma, Org. Lett. 2011,
13, 1254; d) N. Kurono, N. Nii, Y. Sakaguchi, M. Uemura, T. Ohkuma,
Angew. Chem. 2011, 123, 5655; Angew. Chem. Int. Ed. 2011, 50, 5541;
e) M. Uemura, N. Kurono, T. Ohkuma, Org. Lett. 2012, 14, 882; f) M.
Uemura, N. Kurono, Y. Sakai, T. Ohkuma, Adv. Synth. Catal. 2012, 354,
2023; g) Y. Sakaguchi, N. Kurono, K. Yamauchi, T. Ohkuma, Org. Lett.
2014, 16, 808.
Acknowledgements
We are grateful for financial support from NSFC (Grants 21232007,
21202155, 21672002), Chinese Academy of Science (Grant
XDB20020000), Anhui Provincial Natural Science Foundation
(1408085QB24), Young Talent Program in Anhui Provincal
University (gxyqZD2017017) and the Opening Project of State Key
Laboratory of Tea Plant Biology and Utilization (SKLTOF20150108).
[7]
[8]
J. Yu, H.-J. Jiang, Y. Zhou, S.-W. Luo, L.-Z. Gong, Angew. Chem. 2015,
127, 11361; Angew. Chem. Int. Ed. 2015, 54, 11209.
For the diastereoselective synthesis of the anionic chiral CoIII
Complexes, see Supplementary Section 2 for details. The absolute
configurations of the Λ-1e and Δ-1e were assigned by comparison of
their CD spectra with it of Λ-1d. See Supplementary Section 9.2 for
details.
Keywords: chiral CoIII complex • bromoaminocyclization •
Brønsted acid • chiral anion phase-transfer catalysis
[9]
For selected reviews on the halofunctionalizations of alkenes, see: a) G.
Li, S. R. S. S. Kotti, C. Timmons, Eur. J. Org. Chem. 2007, 2745; b) A.
Castellanos, S. P. Fletcher, Chem. Eur. J. 2011, 17, 5766; c) S. E.
Denmark, W. E. Kuester, M. T. Burk, Angew. Chem. 2012, 124, 11098;
Angew. Chem. Int. Ed. 2012, 51, 10938; d) J. Chen, L. Zhou, Synthesis
2014, 46, 586; e) Y. A. Cheng, W. Z. Yu, Y.-Y. Yeung, Org. Biomol.
Chem. 2014, 12, 2333. e) M. H. Gieuw, Z. Ke, Y. -Y. Yeung, Chem.
Record, 2017, 17, 287.
[1]
For selected reviews on chiral anions catalysis, see: a) J. Lacour, V.
Hebbe-Viton, Chem. Soc. Rev. 2003, 32, 373; b) J. Lacour, D.
Moraleda, Chem. Commun. 2009, 7073; c) Z. Zhang, P. R. Schreiner,
Chem. Soc. Rev. 2009, 38, 1187; d) M. Wenzel, J. R. Hiscock, P. A.
Gale, Chem. Soc. Rev. 2012, 41, 480; e) R. J. Phipps, G. L. Hamilton,
F. D. Toste, Nature Chem. 2012, 4, 603; f) M. Mahlau, B. List, Angew.
Chem. 2013, 125, 540; Angew. Chem. Int. Ed. 2013, 52, 518; g) K.
Brak, E. N. Jacobsen, Angew. Chem. 2013, 125, 558; Angew. Chem.
Int. Ed. 2013, 52, 534.
[10] For selected examples of enantioselective bromocyclization, see: a) D.
Huang, H. Wang, F. Xue, H. Guan, L. Li, X. Peng, Y. Shi, Org. Lett.
2011, 13, 6350; b) S. E. Denmark, M. T. Burk, Org. Lett. 2012, 14, 256;
c) L. Zhou, J. Chen, C. K. Tan, Y.-Y. Yeung, J. Am. Chem. Soc. 2011,
133, 9164; d) Y.-M. Wang, J. Wu, C. Hoong, V. Rauniyar, F. D. Toste, J.
Am. Chem. Soc. 2012, 134, 12928; e) F. Chen, C. K. Tan, Y.-Y. Yeung,
J. Am. Chem. Soc. 2013, 135, 1232; f) Z. Ke, C. K. Tan, F. Chen, Y. -Y.
Yeung, J. Am. Chem. Soc. 2014, 136, 5627; g) D. W. Tay, G. Y. C.
Leung, Y. -Y. Yeung, Angew. Chem. 2014, 126, 5261; Angew. Chem.
Int. Ed. 2014, 53, 5161; h) Y.-C. Wong, Z. Ke, Y.-Y. Yeung, Org. Lett.
2015, 17, 4944; i) Y. A. Cheng, W. Z. Yu, Y. -Y. Yeung, Angew. Chem.
2015, 127, 12270; Angew. Chem. Int. Ed., 2015, 54, 12102; j) Y.
Kawato, H. Ono, A. Kubota, Y. Nagao, N. Morita, H. Egami, Y.
Hamashima, Chem. Eur. J. 2016, 22, 2127; k) R. C. Samanta, H.
Yamamoto, J. Am. Chem. Soc. 2017, 139, 1460.
[2]
For selected examples on chiral anions catalysis, see: a) D. B.
Llewellyn, D. Adamson, B. A. Arndtsen, Org. Lett. 2000, 2, 4165; b) C.
Carter, S. Fletcher, A. Nelson, Tetrahedron: Asymmetry 2003, 14, 1995;
c) G. L. Hamilton, T. Kanai, F. D. Toste, J. Am. Chem. Soc. 2008, 130,
14984; d) T. Akiyama, J. Itoh, K. Yokota, K. Fuchibe, Angew. Chem.
2004, 116, 1592; Angew. Chem. Int. Ed. 2004, 43, 1566; e) D. Uraguchi,
M. Terada, J. Am. Chem. Soc. 2004, 126, 5356; f) S. Mayer, B. List,
Angew. Chem. 2006, 118, 4299; Angew. Chem. Int. Ed. 2006, 45, 4193;
g) G. L. Hamilton, E. J. Kang, M. Mba, F. D. Toste, Science 2007, 317,
496; h) M. S. Sigman, E. N. Jacobsen, J. Am. Chem. Soc. 1998, 120,
4901; i) M. S. Sigman, P. Vachal, E. N. Jacobsen, Angew. Chem. 2000,
112, 1336; Angew. Chem. Int. Ed. 2000, 39, 1279.
[11] For selected reviews on the applications of organohalogen cyclic
compounds, see: a) G. W. Gribble, Acc. Chem. Res. 1998, 31, 141; b)
M. North, Sustainable catalysis: without metal or other endangered
elements, RSC, Cambridge, 2015; c) W. Chung, C. D. Vanderwal,
Angew. Chem. 2016, 128, 4470; Angew. Chem. Int. Ed. 2016, 55, 4396;
d) I. Saikia, A. J. Borah, P. Phukan, Chem. Rev. 2016, 116, 6837.
[12] D. H. Miles, M. Veguillas, F. D. Toste, Chem. Sci. 2013, 4, 3427.
[13] CCDC: 1528892 for 3o and CCDC: 1529006 for 3x, see
Supplementary Section 8 for details. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
[3]
For reviews on chiral-at-metal complexes in catalysis, see: a) H.
Brunner, Angew. Chem. 1999, 111, 1248; Angew. Chem. Int. Ed. 1999,
38, 1194; b) P. D. Knight, P. Scott, Coord. Chem. Rev. 2003, 242, 125;
c) M. Fontecave, O. Hamelin, S. Ménage, Top. Organomet. Chem.
2005, 15, 271; d) E. B. Bauer, Chem. Soc. Rev. 2012, 41, 3153; e) L.
Gong, L.-A. Chen, E. Meggers, Angew. Chem. 2014, 126, 11046;
Angew. Chem. Int. Ed. 2014, 53, 10868; f) Z.-Y. Cao, W. D. G. Brittain,
J. S. Fossey, F. Zhou, Catal. Sci. Technol. 2015, 5, 3441.
[4]
For selected examples of anionic chiral CoIII complexes employing
chiral ligands, see: a) Y. N. Belokon, V. I. Maleev, D. A. Kataev, I. L.
Mal’fanov, A. G. Bulychev, M. A. Moskalenko, T. F. Saveleva, T. V.
Skrupskaya, K. A. Lyssenko, I. A. Godovikov, M. North,
Tetrahedron:Asymmetry 2008, 19, 822; b) Y. N. Belokon, V. I. Maleev,
D. A. Kataev, T. F. Saveleva, T. V. Skrupskaya, Y. V. Nelyubina, M.
North, Tetrahedron: Asymmetry 2009, 20, 1746; c) V. I. Maleev, T. V.
Skrupskaya, L. V. Yashkina, A. F. Mkrtchyan, A. S. Saghyan, M. M. Il’in,
D. A. Chusov, Tetrahedron: Asymmetry 2013, 24, 178.
[14] For selected reviews, see: a) O. V. Serdyuk, C. M. Heckel, S. B. Tso-
goeva, Org. Biomol. Chem. 2013, 11, 7051; b) P. Chauhan, S. Mahajan,
U. Kaya, D. Hack, D. Enders, Adv. Synth. Catal. 2015, 357, 253.
[15] See Supplementary Section 5.2 for details.
[16] For early reports on organocatalytic Michael reactions, see: a) B. List, P.
Pojarliev, H. J. Martin, Org. Lett. 2001, 3, 2423; b) J. M. Betancort, K.
Sakthivel, R. Thayumanavan, C. F. Barbas III, Tetrahedron Lett. 2001,
42, 4441; c) J. M. Betancort, C. F. Barbas III, Org. Lett. 2001, 3, 3737;
d) A. Alexakis, O. Andrey, Org. Lett. 2002, 4, 3611; e) T. Ishii, S.
Fujioka, Y. Sekiguchi, H. Kotsuki, J. Am. Chem. Soc. 2004, 126, 9558; f)
C. L. Cao, M. C. Ye, X. L. Sun, Y. Tang, Org. Lett. 2006, 8, 2901.
[17] See Supplementary Section 5.3 for details.
[5]
The chiral CoIII-complex with two perpendicular tridentate ligands, which
are the Schiff bases of salicylaldehydes and (S)-amino acids, exist as
meridional Δ- and Λ-stereoisomers respectively, to left and right spiral
arrangement of ligands in relation to the C2 axis of the complexes, see:
a) J. I. Legg, B. E. Douglas, J. Am. Chem. Soc. 1966, 88, 2697. For the
earlier synthesis of the chiral CobaltIII-complex, see: b) R. C. Burrows, J.
C. Bailar, J. Am. Chem. Soc. 1966, 88, 4150.
[18] See Supplementary Section 6 for details.
This article is protected by copyright. All rights reserved.

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
[19] For selected examples, see: a) V. Rauniyar, A. D. Lackner, G. L.
Hamilton, F. D. Toste, Science 2011, 334, 1681; b) R. J. Phipps, K.
Hiramatsu, F. D. Toste, J. Am. Chem. Soc. 2012, 134, 8376; c) T. Chen,
T. J. Y. Foo, Y.-Y. Yeung, ACS Catal. 2015, 5, 4751; d) H. M. Nelson,
B. D. Williams, J. Mirꢀ, F. D. Toste, J. Am. Chem. Soc. 2015, 137, 3213;
e) E. Yamamoto, M. J. Hilton, M. Orlandi, V. Saini, F. D. Toste, M. S.
Sigman, J. Am. Chem. Soc. 2016, 138, 15877; f) S. Narute, R. Parnes,
F. D. Toste, D. Pappo, J. Am. Chem. Soc. 2016, 138, 16553.
This article is protected by copyright. All rights reserved.

10.1002/anie.201705066
Angewandte Chemie International Edition
COMMUNICATION
COMMUNICATION
Brønsted acids of anionic chiral CoIII
complexes have been found to act as
bifunctional phase-transfer catalysts to
shuttle the substrates across interface
and control stereoselectivity. The
diastereomeric chiral CoIII-templated
Brønsted acids with the same chiral
Hua-Jie Jiang, Kun Liu, Jie Yu,* Ling
Zhang and Liu-Zhu Gong*
Page No. – Page No.
Switchable Stereoselectivity in
Bromoaminocyclization of Olefins
Catalyzed by Brønsted Acids of
Anionic Chiral CoIII Complexes
ligands
enabled
a
switchably
enantioselective
bromoamino-
cyclization of olefins to afford two
opposite enantiomers of 2-substituted
pyrrolidines
with
high
stereoselectivities (up to 99:1 e.r.),
respectively.
This article is protected by copyright. All rights reserved.