Highly Enantioselective Catalytic Carbon Dioxide Incorporation Reaction: Nickel-Catalyzed Asymmetric Carboxylative Cyclization of Bis-1,3-dienes

Article abstract of DOI:10.1021/ja049506y

A method for nickel-catalyzed asymmetric carbon dioxide (CO₂) incorporation via carbon-carbon bond formation was developed. In the presence of a catalytic amount of Ni(acac)₂ and MeO-MOP, various bis-1,3-dienes reacted with CO_2<

Full text of DOI:10.1021/ja049506y

Published on Web 04/22/2004
Highly Enantioselective Catalytic Carbon Dioxide Incorporation Reaction:
Nickel-Catalyzed Asymmetric Carboxylative Cyclization of Bis-1,3-dienes
Masanori Takimoto, Yoichi Nakamura, Kaoru Kimura, and Miwako Mori*
Graduate School of Pharmaceutical Sciences, Hokkaido UniVersity, Hokkaido, Sapporo 060-0812, Japan
Received January 28, 2004; E-mail: mori@pharm.hokudai.ac.jp
Chart 1. Chiral Phosphine Ligands Screened for Asymmetric
Carbon dioxide (CO2) is regarded as an important source of C1
due to its abundant reserve and low toxicity. Hence, the develop-
ment of transition metal-catalyzed reactions for CO2 incorporation
onto organic molecules is of great importance.1 It is especially quite
challenging to develop efficient catalytic protocols that enable
carbon-carbon bond formation between CO2 and substrates in an
enantioselective manner. However, such catalytic asymmetric CO2
incorporation processes have rarely been explored2 due to the
limited number of available catalytic carbon-carbon bond-forming
CO2 incorporation reactions that can be efficiently carried out under
mild conditions.3,4 In the course of our research focused on nickel-
promoted CO2 incorporation reactions,5 we found that Ni(acac)2
and PPh3 could catalyze the addition of CO2 and diorganozinc to
bis-1,3-diene 1 under very mild conditions (eq 1).5c This process
was accompanied by carbocyclization of the bis-1,3-diene moiety
to afford cyclic carboxylic acid 2 in a highly regio- and stereose-
lective manner. Here we report a transition metal-catalyzed highly
enantioselective carbon-carbon bond-forming CO2 incorporation
reaction based on this carboxylative cyclization.
Carboxylative Cyclization of Bis-1,3-diene
Table 1. Asymmetric Carboxylative Cyclization of 1a Using Me2Zn
a
entry
ligand (mol %)
conditions
yield, %
ee, %
config.b
1
2
3
4
5
6
7
8
(R)-BINAP (10)
rt, 23 h
rt, 24 h
rt, 13 h
rt, 15 h
rt, 33 h
rt, 24 h
rt, 4 h
52
62
75
67
38
66
83
71
12
11
55
3
15
43
91
93
2S
2S
2R
2S
2R
2S
2S
2S
(S)-(R)-BPPFA (10)
(R,R)-DIOP (10)
(S)-NMDPP (20)
(S)-PHOX (20)
(S)-(R)-PPFA (20)
(S)-MeO-MOP (20)
(S)-MeO-MOP (20)
We first screened various chiral phosphine ligands (Chart 1) in
carboxylative cyclization of 1a using Me2Zn. The reactions were
carried out in the presence of Ni(acac)2 (10 mol %), chiral phosphine
ligands (10 mol % for bisphosphines or 20 mol % for monophos-
phines), and Me2Zn (4.5 equiv) at room temperature under a CO2
atmosphere (1 atm) in THF. The results are summarized in Table
1. While the reactions using common chiral ligands provided 2a5c
in relatively good yields, the enantioselectivities were moderate
(entries 1-6). The highest enantioselectivity was achieved with the
use of (S)-MeO-MOP as a chiral ligand.7 The reaction of 1a with
CO2 and Me2Zn at room temperature in the presence of (S)-MeO-
MOP afforded 2a in 83% yield and 91% ee (entry 7). The reaction
performed at a lower temperature (0 °C) resulted in higher
enantioselectivity (93% ee) with a slight decrease in chemical yield
(entry 8). The absolute configuration of a chiral center at the C-2
position of 2a, which was obtained in this reaction, was confirmed
to be S according to Kusumi’s method for determining the absolute
configuration of carboxylic acids.8
0 °C, 24 h
a The enantiomeric excess was determined by HPLC analysis with a chiral
stationary phase column. b Absolute configuration of chiral center at the
C-2 position.
Scheme 1. Asymmetric Carboxylative Cyclization of 1e
Encouraged by these results, asymmetric carboxylative cycliza-
tion using MeO-MOP was further investigated (Table 2). When
Ph2Zn was used as an organozinc reagent with bisdiene 1a,
phenylative cyclization proceeded in a highly enantioselective
manner to afford 3a in 81% yield and 95% ee (entry 1). In the
reaction of 1a with Et2Zn, reductive cyclization product 5 was also
obtained in 13% yield (94% ee) along with ethylative cyclization
product 4a (57% yield, 94% ee). The similarity of the enantiose-
lectivities of 4a and 5 suggested that these products were produced
from a same intermediate. The formation of 5 was rationalized by
considering a transfer of â-hydride from the ethyl group via a
â-hydride elimination process.5c Bisdienes 1b, 1c, and 1d were also
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J. AM. CHEM. SOC. 2004, 126, 5956-5957
10.1021/ja049506y CCC: $27.50 © 2004 American Chemical Society

C O M M U N I C A T I O N S
Table 2. Asymmetric Carboxylative Cyclization Using MeO-MOPa
proceeded at 4 °C with regioselective introduction of CO2 into a
less-substituted 1,3-diene moiety to afford 2e in 88% yield and 96%
ee. Phenylative cyclization of 1e also proceeded smoothly in a
regioselective manner under similar conditions to give 3e in 87%
yield and 91% ee.
In conclusion, we have developed a nickel-catalyzed asymmetric
carboxylative cyclization of bis-1,3-dienes. This reaction can be
carried out easily under mild conditions, and the yields and
enantioselectivities are generally high. Further investigation to
expand the scope of this reaction is in progress.
Acknowledgment. This work was supported by The Akiyama
Foundation and by a Grant-in-Aid for Scientific Research (No.
14771235) from the Ministry of Education, Culture, Sports, Science
and Technology, Japan, which are gratefully acknowledged.
Supporting Information Available: Spectral data for all new
compounds, typical procedures for enantioselective carboxylations,
procedures for determination of the stereochemistry, enantiomeric
excess, and absolute configuration (PDF). This material is available
free of charge via the Internet at http://pubs.acs.org.
References
(1) Reviews: Arakawa, H.; Aresta, M.; Armor, J. N.; Barteau, M. A.;
Beckman, E. J.; Bell, A. T.; Bercaw, J. E.; Creutz, C.; Dinjus, E.; Dixon,
D. A.; Domen, K.; DuBois, D. L.; Eckert, J.; Fujita, E.; Gibson, D. H.;
Goddard, W. A.; Goodman, W.; Keller, J.; Kubas, G. J.; Kung, H. H.;
Lyons, J. E.; Manzer, L. E.; Marks, T. J.; Morokuma, K.; Nicholas, K.
M.; Periana, R.; Que, L.; Rostrup-Nielson, J.; Sachtler, W. M. H.; Schmidt,
L. D.; Sen, A.; Somorjai, G. A.; Stair, P.; Stults, B. R.; Tumas, W. Chem.
ReV. 2001, 101, 953.
(2) To the best of our knowledge, there is no report on a catalytic
enantioselective carbon-carbon bond-forming CO2 incorporation reaction,
although some examples of zinc-catalyzed asymmetric alternating copo-
lymerization of cyclohexene oxide and CO2 have recently been reported.
(a) Nozaki, K.; Nakano, K.; Hiyama, T. J. Am. Chem. Soc. 1999, 121,
11008. (b) Nakano, K.; Nozaki, K.; Hiyama, T. J. Am. Chem. Soc. 2003,
125, 5501. (c) Cheng, M.; Darling, N. A.; Lobkovsky, E. B.; Coates, G.
W. Chem. Commun. 2000, 30, 2007.
(3) Reviews: (a) Behr, A. Angew. Chem., Int. Ed. Engl. 1988, 27, 661. (b)
Braunstein, P.; Matt, D.; Nobel, D. Chem. ReV. 1988, 88, 747. (c) Leitner,
W. Coord. Chem. ReV. 1996, 153, 257. (d) Yin, X.; Moss, J. R. Coord.
Chem. ReV. 1999, 181, 27. (e) Walther, D.; Ruben, M.; Rau, S. Coord.
Chem. ReV. 1999, 182, 67.
(4) Louie recently reported efficient catalytic procedure for [2 + 2 + 2]
cycloaddition of diyne and CO2 under mild conditions. Louie, J.; Gibby,
J. E.; Farnworth, M. V.; Tekavec, T. N. J. Am. Chem. Soc. 2002, 124,
15188.
(5) (a) Takimoto, M.; Mori, M. J. Am. Chem. Soc. 2001, 123, 2895. (b)
Takimoto, M.; Shimizu, K.; Mori, M. Org. Lett. 2001, 3, 3345. (c)
Takimoto, M.; Mori, M. J. Am. Chem. Soc. 2002, 124, 10008. (d) Shimizu,
K. Takimoto, M.; Mori, M. Org. Lett. 2003, 5, 2323. (e) Takimoto, M.
Kawamura, M.; Mori, M. Org. Lett. 2003, 5, 2599. For recent examples
reported from other laboratories, see ref 6 and references cited in ref 3.
(6) Saito, S.; Nakagawa, S.; Koizumi, T.; Hirayama, K.; Yamamoto, Y. J.
Org. Chem. 1998, 64, 3975.
(7) For reviews on enantioselective reactions using MOP derivatives, see:
(a) Hayashi, T. Acc. Chem. Res. 2000, 33, 354. For preparation of MeO-
MOP, see: (b) Uozumi, Y.; Kawatsura, M.; Hayashi, T. Org. Synth. 2002,
78, 1. (c) Uozumi, Y.; Tanahashi, A.; Lee, S.-Y.; Hayashi, T. J. Org.
Chem. 1993. 58, 1945.
a All reactions were carried out in the presence of Ni(acac)2 (10 mol
%), (S)-MeO-MOP (20 mol %), and an organozinc reagent (4.5 equiv) under
an atmosphere of CO2 (1 atm) in THF. b All products were isolated as methyl
esters after treatment with CH2N2. The absolute configurations of all
products were unequivocally determined as indicated above. For details,
see Supporting Information.
applicable to the asymmetric carboxylative cyclization, and the
desired products having a carbocyclic five-membered ring skeleton
were obtained in high yields and in high enantioselectivities (entries
3-8).
It is notable that unsymmetrical bis-1,3-diene 1e could be used
in this asymmetric carboxylation with high selectivity (Scheme 1).
Methylative cyclization of 1e in the presence of (S)-MeO-MOP
(8) Nagai, Y.; Kusumi, T. Tetrahedron Lett. 1995, 36, 1853. For details, see
Supporting Information.
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