Rhodium-catalyzed carbocyclization and chlorosulfonylation of 1,6-enynes with sulfonyl chlorides

Article abstract of DOI:10.1002/chem.201204039

The financial support from NSFC (No. 21002025 and 21272066), the Fundamental Research Funds for the Central Universities, Shanghai Rising- Star Program (11 A1401700), and Specialized Research Fund for the Doctoral Program of Higher Education (201000741200

Full text of DOI:10.1002/chem.201204039

DOI: 10.1002/chem.201204039
Rhodium-Catalyzed Carbocyclization and Chlorosulfonylation of 1,6-Enynes
with Sulfonyl Chlorides
Chen Chen, Jianhua Su, and Xiaofeng Tong*[a]
The transition-metal catalyzed cyclization of enyne has
been one of the most efficient methods for the synthesis of
various types of cyclic compounds.[1] The metal-catalyzed ad-
dition–carbocyclization reactions[2] of 1,6-enyne with re-
our continuous research on the catalytic cyclization of 1,6-
enynes,[8] we herein report the first example of the RhI-cata-
lyzed carbocyclization and chlorosulfonylation of 1,6-enynes
with sulfonyl chlorides as a linker, in which three different
À
À
À
À
À
agents containing interheteroatom X Y bonds [X Y=
metal–metal reagent (B, Si, Ge, Sn, etc.),[3] metal–H re-
agent,[4] dihalogen[5]] constitute synthetically highly versatile
bonds, C Cl, C C, and C S, are efficiently formed with
high regioselectivity and stereoselectivity (Scheme 1b).
We started our investigation by screening different metal
catalysts for the carbocyclization and chlorosulfonylation re-
action of 1,6-enyne 1a (1 equiv) with TsCl 2a (1.5 equiv).[9]
Whereas most of the tested catalysts, including CuCl, [Fe-
À
processes, which furnish the formation of a new C C bond
À
À
along with C X and C Y bonds in a one-step fashion and
represent a facile route to carbocyclic and heterocyclic ring
systems (Scheme 1a). Although related reactions have been
A
ACHTUGNRTNE(NUNG PPh3)2Cl2], showed no activity for the at-
AHCTUNGTRENNUNG
enable the complete consumption of 1a, although a compli-
cated reaction resulted (Table 1, entry 1). Fortunately, com-
Table 1. Optimization of reaction conditions.[a]
Scheme 1. Metal-catalyzed addition–cyclization of 1,6-enyne.
extensively investigated recently, their power and scope is
ultimately impeded by the limitation of the above-men-
tioned linkers; no other type of s-bond linkers, to the best
of our knowledge, have been reported. Therefore, the devel-
opment of novel linkers for the addition–carbocyclization
reactions, especially under the guidance of novel reaction
mechanism(s), is still highly desirable.
Recent discoveries have heralded a renaissance for sulfon-
yl chlorides as readily available, inexpensive, and versatile
reagents for metal-catalyzed transformations.[6] It occurred
to us that sulfonyl chlorides might serve as a novel linkers
for catalytic addition–carbocyclization reactions. In fact, the
addition of sulfonyl chlorides across terminal alkynes has
been successfully achieved with the assistance of Cu or Fe
complexes,[7] demonstrating their similar potential[2] as for
the above mentioned element–element linkers. As part of
Entry
x
[Rh]
L
Additive
Yield[b]
[%]
[c]
[c]
1
2
3
4
5
6
7
8
1.5
1.5
1.5
1.5
1.5
1.5
2.0
2.5
[Rh
[Rh
[Rh
[Rh
[Rh
[Rh
[Rh
[Rh
G
–
–
–
6
[c]
R
LiCl–H2O[d]
LiCl–H2O
LiCl–H2O
LiCl–H2O
LiCl–H2O
LiCl–H2O
LiCl–H2O
43
77
42
26
30
83
92
E
DPPF
DPPE
DPPP
DPPB
DPPF
DPPF
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
[a] Reaction conditions: enyne
(0.02 mmol), ligand (0.022 mmol), 3 mL dioxane. [b] Yield of isolated
product. [c] Without ligand or additive. [d] 1.0 equiv LiCl–H2O was used.
1
(0.2 mmol), catalyst precursor
pound 3aa was indeed obtained, albeit only in 6% yield
after very careful chromatography. The structure of 3aa was
unambiguously determined by X-ray diffraction analysis
(Figure 1, left).[10] The (E)-configuration of exo-double bond
in 3aa implied that the chloride might attack the triple bond
of 1a from the opposite direction of alkyne–rhodium com-
plex (see below). Indeed, the addition of LiCl–H2O
(1 equiv) significantly improved the reaction performance,
leading to the isolation of 3aa in 43% yield (Table 1,
entry 2). These promising results promted us to test the
[a] C. Chen, Prof. J. Su, Dr. X. Tong
Shanghai Key Laboratory of Functional Materials Chemistry
East China University of Science and Technology
Meilong Road, 130, Shanghai 200237 (P.R. China)
Fax : (+86)21-64253881
E-mail: tongxf@ecust.edu.cn
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201204039.
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COMMUNICATION
Table 2. The scope of the reactions of enynes with 2a.[a]
1,6-Enyne 1
1a: R=Me, X=NTs
3, Yield [%][b]
3aa, 92
3ba, 62
3ca, 41
3da, 45[c]
3ea, 75
1b: R=Et, X=NTs
1c: R=Ph, X=NTs
1d: R=H, X=NTs
1e: R=Me, X=O
1 f: R=4-CN-C6H4
1g: R=4-Ac-C6H4
1h: R=4-Me-C6H4
3 fa, 61
3ga, 58
3ha, 98
1i: R=Ph
1j: R=Bu
3ia, 47
3ja, 40
[a] Reaction conditions: enyne 1 (0.2 mmol), TsCl (0.5 mmol), LiCl–H2O
(0.2 mmol), [Rh(cod)Cl] (0.02 mmol), DPPF (0.022 mmol), 3 mL dioxane.
AHCTUNGTRENNUNG
[b] Yield of isolated product. [c] With some unidentified byproducts.
products in lower yields, whereas the reaction of substrate
1h with a 4-Me-C6H4 group on the alkyne moiety gave a
near-quantitative amount of 3ha. When the substrates with
electron-poor alkyne moieties, such as 1i and 1j, were em-
ployed, the yield was also decreased to around 40%. We
were pleased to find that the transformation was also appli-
cable to the oxygen-tethered enyne. Indeed, the reaction of
substrate 1e gave product 3ea in the yield of 75%.
The catalytic carbocyclization and chlorotosylation reac-
tion was then extended to other sulfonyl chlorides. As
shown in Table 3, a wide range of sulfonyl chlorides reacted
well with 1,6-enyne 1a, and generally good yields were ach-
ieved. No reaction was observed in the case of mesitylsul-
fonyl chloride 2g, likely due to its large steric hindrance.
Notably, the reaction could also be realized for methanesul-
fonyl chloride 2h, resulting in the isolation of 3ah in 78%
yield.
Figure 1. X-ray crystal structures of 3aa (top) and 3aa-I (bottom).
effect of ligand on the reaction performance with the use of
[RhACHTUNGTRENNUNG(cod)Cl] (cod=cyclooctadiene) as a catalyst precursor
and LiCl–H2O as an additive. When 1,1’-bis(diphenylphos-
phino)ferrocene (DPPF) ligand was used, the yield of 3aa
was further increased to 77% (Table 1, entry 3). We further
examined a variety of ligands, such as 1,2-bis(diphenylphos-
phino)ethane (DPPE), 1,3-bis(diphenylphosphino)propane
(DPPP), and 1,4-bis(diphenylphosphino)butane (DPPB),
which did not exhibit any superior performance over DPPF
(Table 1, entries 4–6). To our delight, when 2 equivalents of
TsCl was used the reaction performance was significantly
improved, providing 3aa in 83% yield (Table 1, entry 7).
The use of 2.5 equivalents of TsCl could further increase the
yield to 92% (Table 1, entry 8).
After establishing the optimized reaction conditions, we
surveyed the synthetic scope of the reaction with various
1,6-enynes (Table 2). In general, a wide range of 1,6-enynes
reacted well with TsCl 2a to afford the corresponding prod-
ucts in moderate to excellent yields. The reaction of 1b with
ethyl substitution on the alkene moiety gave 3ba in 62%
yield, whereas in the case of 1c with phenyl substitution, the
corresponding yield of 3ca dropped to 41%. The depend-
ence of the yield upon substitution partners likely relied on
the corresponding steric hindrance. However, the reaction
of enyne 1d with single-substituted alkene was somewhat
complicated, affording the desired product 3da in 45%
yield along with some unidentified byproducts. Similarly,
substitution on the alkyne moiety also strongly affected the
reaction performance. Indeed, enynes 1 f and 1g with elec-
tron-poor aromatic substitution gave the corresponding
To gain a better understanding of the reaction mechanism,
a series of control experiments were conducted. In a first set
of experiments, compounds 4 and 5 were instead employed
as substrates and subjected to the optimized conditions, re-
spectively [Eq. (1)]. No corresponding chlorotosylation
products were observed and the starting materials were re-
covered nearly quantitatively. These results clearly indicated
that the combination of alkene and alkyne moieties into one
molecule might be essential for this RhI-catalyzed transfor-
mation.
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X. Tong et al.
Table 3. The scope of the reactions of 1a with sulfonyl chlorides.[a]
In a final set of experiments, we employed the deuterium-
À
labelled enyne to investigate the chemistry of the C S bond
formation. Indeed, enyne 1b-D, with a (Z)-configured termi-
nal olefin, reacted well with 2a to give product 3ba-D in
70% yield without deuterium erosion but with deuterium
scrambling [Eq. (2)].
2
3, Yield [%][b]
2a: R1 =Me
3aa, 92
2b: R1 =OMe
2c: R1 =H
3ab, 90
3ac, 90
3ad, 72
2d: R1 =Cl
2e
3ae, 62
Apparently, the observation of deuterium scrambling
seems to support the radical-involved reaction mechanism.
However, a control experiment showed that the presence of
the radical inhibitor, butylhydroxytoluene (BHT) or 2,2,6,6-
tetramethylpiperidin-1-yl)oxyl (TEMPO), did not affect the
carbocyclization and chlorotosylation reaction of 1b with
TsCl and 3ba was still isolated in around 60% yield. These
results are particularly interesting because a free-radical,
redox-transfer chain mechanism has been generally accepted
for the metal-catalyzed addition of sulfonyl chloride to ter-
2 f
2g
2h
3af, 47
3ag, 0
minal alkynes[7] or alkenes[11]
.
3ah, 78
Although highly speculative, the above results led us to
propose the mechanism depicted in Scheme 3 for the pres-
ent transformation (with 1b-D and 2a as substrates). This
[a] Reaction conditions: 1a (0.2 mmol), sulfonyl chloride (0.5 mmol),
LiCl–H2O (0.2 mmol), [Rh(cod)Cl] (0.02 mmol), DPPF (0.022 mmol),
3 mL dioxane. [b] Yield of isolated product.
AHCTUNGTRENNUNG
In another set of experiments, the possibility of the corre-
sponding carbocyclization and bromotosylation or iodotosy-
lation was investigated (Scheme 2). To our delight, the bro-
Scheme 3. Mechanistic proposal [(M=RhIII)].
Scheme 2. Carbocyclizative bromotosylation and iodotosylation.
could initially involve oxidative addition of TsCl to the RhI
center.[12] Indeed, ESI-MS analysis of the reaction between
motosylation product 3aa-Br was readily obtained in 88%
yield with the use of LiBr–H2O as additive under otherwise
identical conditions. For iodotosylation, the catalyst precur-
[Rh
lowed us to identify the intermediate [Rh
(dioxane)TsCl2] according to the high resolution mass data
([C45H43Cl2FeO4P2SRh+Na]+
calcd 993.0031, found
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
sor [RhCl(CO)
N
ACHTUNGTRENNUNG
optimal, giving 3aa-I in 57% yield (isolated product;
Scheme 2). The structure of 3aa-I was also determined by
X-ray diffraction analysis.[10] These results further pointed
993.0021). Furthermore, a 31P NMR spectroscopic study on
this reaction indicates the formation of two species. Both
species show doublet signals: 22.98 ppm (JPÀRh =152 Hz) and
22.58 ppm (JPÀRh =151 Hz).[13] These species might corre-
spond to two RhIII complexes cis-A1 and cis-A2[14] that are
À
out that the formation of the C X bond might arise from an
anti-halo-rhodation process, furnishing the exo-double bond
with (E)-configuration.
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Carbocyclization and Chlorosulfonylation of 1,6-Enynes
COMMUNICATION
formed by the oxidative addition of TsCl to a RhI-center
(Scheme 3). Therefore, they are likely to be present in solu-
tion and thus potential intermediates in the catalytic cycle.
We speculated that alkyne and alkene of 1b-D preferential-
ly coordinate to the RhIII center of cis-A2 due to its cationic
character, generating complex B. Subsequently, the activated
alkyne is attacked by external chloride to form the vinyl-
RhIII intermediate C.[15] Afterwards, alkene stereospecifically
inserts into the vinyl–RhIII bond of intermediate C to form
the alkyl-RhIII intermediate D with well-defined stereo-
chemistry,[16] which is followed by reductive elimination of
1997, 1229; f) M. Gerdin, S. K. Nadakudity, C. Worch, C. Moberg,
Adv. Synth. Catal. 2010, 352, 2559; g) Y.-T. Hong, S.-K. Yoon, S.-K.
Kang, C.-M. Yu, Eur. J. Org. Chem. 2004, 4628.
[4] For related reports on addition–carbocyclization reactions of 1,6-
enyne with the use of R3SiH, R3SnH, and R2BH, see: a) I. Ojima,
A. T. Vu, S.-Y. Lee, J. V. McCullah, A. C. Moralee, M. Fujiwara,
T. H. Hoang, J. Am. Chem. Soc. 2002, 124, 9164; b) P. Kisanga,
R. A. Widenhoefer, J. Am. Chem. Soc. 2000, 122, 10017; c) M. Laut-
ens, J. Mancuso, Org. Lett. 2000, 2, 671; d) H. Chakrapani, C. Liu,
R. A. Widenhoefer, Org. Lett. 2003, 5, 157; e) A. R. Muci, J. E.
Bercaw, Tetrahedron Lett. 2000, 41, 7609.
[5] For examples of Pd-catalyzed carbocyclization and dihalogenation
of 1,6-enynes, see: a) X. Lu, Handbook of OrganopalladiumChemis-
try for Organic Synthesis Vol. 2 (Ed.: E. J. Nigishi), Wiley-VCH,
Weinheim, 2002, pp. 2267; b) X. Lu, G. Zhu, Z. Wang, Synlett 1998,
115; c) G. Yin, G. Liu, Angew. Chem. 2008, 120, 5522; Angew.
Chem. Int. Ed. 2008, 47, 5442; d) J. Ji, C. Zhang, X. Lu, J. Org.
Chem. 1995, 60, 1160; e) T. Gilbert, F. Hadley, M. Simmons, C.
Bauer, R. Rogers, J. Organomet. Chem. 1996, 510, 83; f) H. Jiang, S.
Ma, G. Zhu, X. Lu, Tetrahedron 1996, 52, 10945.
À
the alkyl-Rh S bond to form product 3ba-D and regenerate
the RhI catalyst. The observation of deuterium scrambling
led us to hypothesize that the reductive elimination might
proceed via two different pathways, SN2-type or direct re-
ductive elimination.[17] Although the proposed mechanism
lacks solid evidence, it does account for the observed chemi-
cal outcome, especially the stereochemistry of the exocyclic
[6] S. R. Dubbaka, P. Vogel, Angew. Chem. 2005, 117, 7848; Angew.
Chem. Int. Ed. 2005, 44, 7674.
À
alkene and the formation of the C S bond. Nevertheless,
[7] a) Y. Amiel, Tetrahedron Lett. 1971, 12, 661; b) Y. Amiel, J. Org.
Chem. 1971, 36, 3691; c) Y. Amiel, J. Org. Chem. 1971, 36, 3697;
d) N. Kamigata, H. Sawada, M. Kobayashi, J. Org. Chem. 1983, 48,
3793; e) X. Liu, X. Duan, Z. Pan, Y. Han, Y. Liang, Synlett 2005,
1752; f) X. Zeng, L. Ilies, E. Nakamura, Org. Lett. 2012, 14, 954;
g) N. Kamigata, T. Shimizu, Rev. Heteroat. Chem. 1997, 17, 1.
[8] a) X. Fang, C. Li, X. Tong, Chem. Commun. 2009, 5311; b) X. Fang,
X. Tong, Tetrahedron Lett. 2010, 51, 317; c) X. Tong, Z. Zhang, X.
Zhang, J. Am. Chem. Soc. 2003, 125, 6370; d) X. Tong, M. Beller,
M. K. Tse, J. Am. Chem. Soc. 2007, 129, 4906.
[9] During our preparation of this manuscript, Nakamura and co-work-
ers reported the Fe-catalyzed carbocyclization and chlorotosylation
of 1,6-enyne (Ref. [7 f]). In their paper, only one 1,6-enyne substrate
was reported. More importantly, the regioselectivity is very different
from our examples. It should be noted that our conditions are not
applicable to the 1,6-enyne with a terminal alkyne group.
[10] CCDC-902637 (3aa) and CCDC-902466 (3aa-I) contain the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
[11] a) M. S. Kharasch, R. A. Mosher, J. Org. Chem. 1952, 17, 453;
b) M. S. Kharasch, A. F. Zavist, J. Am. Chem. Soc. 1951, 73, 964;
c) S. J. Cristol, J. A. Reeder, J. Org. Chem. 1961, 26, 2182; d) S. J.
Cristol, D. I. Davies, J. Org. Chem. 1964, 29, 1282; e) P. S. Skell, J. H.
McNamara, J. Am. Chem. Soc. 1957, 79, 85. For reviews, see: f) F.
Minisci, Acc. Chem. Res. 1975, 8, 165; g) J. Iqbal, B. Bhatia, N. K.
Nayyar, Chem. Rev. 1994, 94, 519.
the exact catalytic mechanism still needs more investigation.
In summary, we have developed a novel RhI-catalyzed
carbocyclization and chlorosulfonylation of 1,6-enyne with
À
sulfonyl chloride, which results in the formation of C Cl,
À
À
C C, and C S bonds in a one-pot fashion. Sulfonyl chloride
is proved to be an efficient linker in addition–carbocycliza-
tion reactions, which complements the known element–ele-
ment examples. Further work will focus on the mechanistic
investigation and synthetic applications of this reaction.[18]
Acknowledgements
The financial support from NSFC (No. 21002025 and 21272066), the Fun-
damental Research Funds for the Central Universities, Shanghai Rising-
Star Program (11 A1401700), and Specialized Research Fund for the
Doctoral Program of Higher Education (20100074120014) are highly ap-
preciated.
Keywords: 1,6-enynes · cyclization · chlorosulfonylation ·
linkers · rhodium · sulfonyl chlorides
[12] a) J. T. Mague, M. O. Nutt, Inorg. Chem. 1977, 16, 1259; although
the oxidative addition of sulfonyl chloride to RhI has not been inves-
tigated in detail, the palladium analogue is a known process, for se-
lected reports, see: b) S. R. Dubbaka, P. Vogel, Org. Lett. 2004, 6,
95; c) S. Zhang, X. Zeng, Z. Wei, D. Zhao, T. Kang, W. Zhang, M.
Yan, M. Luo, Synlett 2006, 891; d) S. R. Dubbaka, P. Vogel, J. Am.
Chem. Soc. 2003, 125, 15292; e) Q. Wu, D. Zhao, X. Qin, J. Lan, J.
You, Chem. Commun. 2011, 47, 9188.
[1] For reviews, see: a) B. M. Trost, Acc. Chem. Res. 1990, 23, 34; b) I.
Ojima, M. Tzamarioudaki, Z. Li, R. J. Donovan, Chem. Rev. 1996,
96, 635; c) B. M. Trost, Chem. Rev. 2001, 101, 2067; d) C. Aubert, O.
Buisine, M. Malacria, Chem. Rev. 2002, 102, 813; e) V. Michelet,
P. Y. Toullec, J.-P. Genet, Angew. Chem. 2008, 120, 4338; Angew.
Chem. Int. Ed. 2008, 47, 4268.
[13] a) S. Chen, X. Li, J. Zhao, W. Li, Inorg. Chem. Inorg.Chem. 2009,
48, 1198; b) E. Kossoy, B. Rybtchinski, Y. Diskin-Posner, J. W.
Shimon, G. Leitus, D. Milstein, Organometallics 2009, 28, 523; c) J.
Hooper, A. Chaplin, C. Gonzꢂlez-Rodrꢃguez, A. Thompon, A.
Weller, M. Willis, J. Am. Chem. Soc. 2012, 134, 2906; d) T. Douglas,
A. Chaplin, A. Weller, J. Am. Chem. Soc. 2008, 130, 14432; e) G.
Williams, C. Parks, C. Smith, H. Adams, A. Haynes, A. Meijer, G.
Sunley, S. Gaemers, Organometallics 2011, 30, 6166.
[2] For reviews, see: a) L.-B. Han, M. Tanaka, Chem. Commun. 1999,
395; b) T. N. Mitchell, Synthesis 1992, 803; c) M. Suginome, Y. Ito,
Chem. Rev. 2000, 100, 3221; d) I. Beletskaya, C. Moberg, Chem. Rev.
1999, 99, 3435; e) I. Beletskaya, C. Moberg, Chem. Rev. 2006, 106,
2320; f) K. Tamao, S. Yamaguchi, J. Organomet. Chem. 2000, 611, 3.
[3] For representative examples of metal–metal reagents, see: a) M.
Mori, T. Hirose, H. Wakamatsu, N. Imakuni, Y. Sato, Organometal-
lics 2001, 20, 1907; b) Y. Sato, N. Imakuni, M. Mori, Adv. Synth.
Catal. 2003, 345, 488; c) Y. Sato, N. Imakuni, T. Hirose, H. Waka-
matsu, M. Mori, J. Organomet. Chem. 2003, 687, 392; d) S.-y. Onoza-
wa, Y. Hatanaka, N. Choi, M. Tanaka, Organometallics 1997, 16,
5389; e) S.-y. Onozawa, Y. Hatanaka, M. Tanaka, Chem. Commun.
[14] The ion [RhACTHNUTRGNEUNG
(DPPF)Cl2]+ (m/z 726.9104, calcd for C34H28Cl2FeP2Rh+
: m/z 726.9442) was also detected.
[15] a) K. Kokubo, K. Matsumasa, M. Miura, M. Nomura, J. Org. Chem.
1996, 61, 6941; b) R. Hua, S. Shimada, M. Tanaka, J. Am. Chem.
Chem. Eur. J. 2013, 19, 5014 – 5018
ꢁ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
5017

X. Tong et al.
Soc. 1998, 120, 12365; c) R. Hua, S.-y. Onozawa, M. Tanaka, Chem.
Eur. J. 2005, 11, 3621; d) T. Kashiwabara, K. Kataoka, R. Hua, S.
Shimada, M. Tanaka, Org. Lett. 2005, 7, 2241; e) T. Kashiwabara, K.
Fuse, R. Hua, M. Tanaka, Org. Lett. 2008, 10, 5469.
116, 598; Angew. Chem. Int. Ed. 2004, 43, 588; c) A. P. Nelson, S. G.
Dimagno, J. Am. Chem. Soc. 2000, 122, 8569; d) J. P. Collman, J. I.
Brauman, A. M. Madonik, Organometallics 1986, 5, 215.
À
[18] Two primary synthetic applications related to the vinyl I bond of
[16] L. Jiao, S. Ye, Z.-X. Yu, J. Am. Chem. Soc. 2008, 130, 7178.
[17] For studies on the reductive elimination of some RhI complexes,
see: a) C. Hahn, M. Spiegler, E. Herdtweck, R. Taube, Eur. J. Inorg.
Chem. 1999, 435; b) M. S. Sanford, J. T. Groves, Angew. Chem. 2004,
3aa-I have been realized. For details, see the Supporting Informa-
tion.
Received: November 12, 2012
Published online: March 7, 2013
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