Cross-coupling reaction of oxo-π-allylnickel complex generated from 1,3-diene under an atmosphere of carbon dioxide

Full text of DOI:10.1021/ja004004f

J. Am. Chem. Soc. 2001, 123, 2895-2896
2895
Scheme 1
Cross-Coupling Reaction of Oxo-π-allylnickel
Complex Generated from 1,3-Diene under an
Atmosphere of Carbon Dioxide
Masanori Takimoto and Miwako Mori*
Graduate School of Pharmaceutical Sciences
Hokkaido UniVersity, Sapporo 060-0812, Japan
ReceiVed NoVember 20, 2000
Despite the possibility of carbon dioxide (CO2) being an
important natural carbon source for building organic molecules,
there is only a limited number of CO2 incorporation reactions
for synthetic organic chemistry. Efficient use of CO2 could be
achieved by the aid of a transition metal complex.1 Low-valent
nickel species have been known to mediate the coupling of CO2
with various unsaturated hydrocarbons via an oxidative cyclo-
addition process.2-6 Among those reactions, the coupling of 1,3-
diene with CO2 is attractive because that process would produce
oxo-π-allylnickel complex 2, which could be converted into
various compounds (eq 1). If complex 2 reacts with another
Table 1. Nickel-Mediated Dicarboxylation of 1,3-Dienes
organometallic reagent, a cross-coupling product 3 can be
obtained. Here we report that organozinc reagents react with oxo-
π-allylnickel complex 2 in quite different manners depending on
the organic moieties on zinc metal.
Although there are several reports on the preparation of
complex 2 from 1,3-diene in the presence of CO2 and a Ni(0)
complex,6 in most cases an excess amount of 1,3-diene and/or
longer reaction time are required. We found that 1,8-diazabicyclo-
[5.4.0]undec-7-ene (DBU) was a superior ligand for nickel-
promoted oxidative coupling of 1a with CO2. In the presence of
DBU (2 equiv to nickel) and Ni(cod)2 (1 equiv), 1a (1.1 equiv)
easily reacted with CO2 (1 atm) under mild conditions (0 °C, 4
h) to afford carboxylic acids 4a-T and 4a-I in 77% yield after
hydrolysis (Scheme 1).7 This result indicated that oxo-π-
allylnickel complexes 2a-T and 2a-I are formed from 1,3-diene
and CO2.
(1) Reviews: (a) Behr, A. Angew. Chem., Int. Ed. Engl. 1988, 27, 661.
(b) Braunstein, P. B.; Matt, D.; Nobel, D. Chem. ReV. 1988, 88, 747. (c)
Gibson, D. H. Chem. ReV. 1996, 96, 2063. (d) Leitner, W. Angew. Chem.,
Int. Ed. Engl. 1995, 34, 2207.
a Isolated yield based on Ni(cod)2. b The crude products were treated
with CH2N2 before isolation. c The crude product was refluxed in MeOH
in the presence of a catalytic amount of p-TsOH.
(2) Alkenes: (a) Behr, A.; Thelen, G. C1 Mol. Chem. 1982, 1, 228. (b)
Hoberg, H.; Peres, Y.; Milchereit, A. J. Organomet. Chem. 1986, 307, C38.
(c) Hoberg, H.; Peres, Y.; Milchereit, A. J. Organomet. Chem. 1986, 307,
C41. (d) Hoberg, H.; Peres, Y.; Kru¨ger, C.; Tsay, Y.-H. Angew. Chem., Int.
Ed. Engl. 1987, 26, 771. (e) Hoberg, H.; Ballesteros, A.; Sigan, A.; Jegat, C.;
Milchereit, A. Synthesis 1991, 395.
(3) Alkynes: (a) Hoberg, H.; Burkhart, G. Angew. Chem., Int. Ed. Engl.
1982, 21, 76. (b) Hoberg, H.; Scha¨fer, D. J. Organomet. Chem. 1982, 238,
383. (c) Hoberg, H.; Scha¨fer, D.; Burkhar, G.; Kru¨ger, C.; Romao, M. J. J.
Organomet. Chem. 1984, 266, 203. (d) Saito, S.; Nakagawa, S.; Koizumi, T.;
Hirayama, K.; Yamamoto, Y. J. Org. Chem. 1998, 64, 3975. For catalytic
reactions involving a related coupling process, see ref 4.
(4) Recent reports: (a) Inoue, Y.; Itoh, Y.; Kazama, H.; Hashimoto, H.
Bull. Chem. Soc. Jpn. 1980, 53, 3329. (b) Tsuda, T.; Morikawa, S.; Hasegawa,
N.; Saegusa, T. J. Org. Chem. 1990, 55, 2978.
(5) Allenes: Hoberg, H.; Oster, B. W. J. Organomet. Chem. 1984, 266,
321.
(6) 1,3-Dienes: (a) Walther, D.; Dinjus, E. Z. Chem. 1982, 22, 228. (b)
Dinjus, E.; Walther, D.; Schu¨tz, H.; Shade, W. Z. Chem. 1983, 23, 303. (c)
Walther, D.; Dinjus, E.; Sieler, J.; Thanh, N. N.; Shade, W.; Leban, I. Z.
Natureforsch. 1983, B38, 835. (d) Walther, D.; Dinjus, E. Z. Chem. 1984, 24,
63. (e) Hoberg, H.; Scha¨fer, D.; Oster, B. W. J. Organomet. Chem. 1984,
266, 313. (f) Hoberg, H.; Apotecher, B. J. Organomet. Chem. 1984, 270,
C15. (g) Walther, D.; Dinjus, E.; Go¨rls, H. J. Organomet. Chem. 1985, 286,
103. (h) Behr, A.; Kanne, U. J. Organomet. Chem. 1986, 317, C41.
We next examined the coupling reaction of π-allynickel
complex 2 with organozinc reagents via a transmetalation process.
When nickel complexes 2a-I and 2a-T, prepared in situ under
the abovementioned conditions, were treated with Me2Zn (5 equiv
to nickel) at 0 °C for 2 h, the desired methylation product 5a-T
or 5a-I was not obtained at all, and an unexpected product,
dimethyl (Z)-3-hexene-1,4-dioate 6a, was obtained in 68% yield
after diazomethane esterification (Table 1, entry 1). The formation
of 6a meant that 1,4-dicarboxylation of 1,3-diene occurred under
these reaction conditions.
To investigate the generality of this reaction, various dienes
were examined (Table 1). In each case, a 1,4-dicarboxylated
product having (Z)-olefin was obtained as a sole product. The
yields were generally good except in the case of 1f (entry 6).
Diene 1e afforded lactone 6e in good yield after treatment with
(7) The use of the other ligands such as 2,2′-bipyridine, TMEDA, or PCy3
was not effective. Hoberg and Yamamoto reported that DBU is a superior
ligand for nickel-promoted carboxylation of alkene and alkyne.2b-d,3d
10.1021/ja004004f CCC: $20.00 © 2001 American Chemical Society
Published on Web 03/02/2001

2896 J. Am. Chem. Soc., Vol. 123, No. 12, 2001
Communications to the Editor
Table 2. Nickel-Mediated Arylative Carboxylation of 1,3-Dienes
Scheme 2
Scheme 3
acid in methanol (entry 5). It was interesting that the dicarboxy-
lation of cyclic 1,3-diene 1g afforded trans-1,4-dicarboxylic acid
7g as a sole product (entry 7).
It is likely that the second carboxylation is initiated by the
formation of a methyl-π-allylnickel complex, such as 8, via a
transmetalation process (Scheme 2, R ) Me), since the presence
of Me2Zn is essential for 1,4-dicarboxylation. Although the
mechanism of this reaction is still unclear, the anti addition of
two CO2 molecules to 1g indicated that the second CO2 formally
attacked from the backside of oxo-π-allylcomplex 8.8,9 The
selective formation of (Z)-olefins suggested that the second
carboxylation proceeds via anti-π-allyl complex 2 with retention
of its geometrical configuration (Scheme 3).
Surprisingly, the use of Ph2Zn, instead of Me2Zn, in the reaction
of 1g afforded methyl cis-4-phenyl-2-cyclohexene carboxylate 13g
(Table 2, entry 1) after diazomethane esterification. The syn
addition of CO2 and a phenyl group to 1g suggested that the
reaction proceeded via transmetalation of 2g with Ph2Zn, affording
9, which then undergoes reductive elimination to give 10 (Scheme
2, R ) Ph).10 The reaction of 1a under similar conditions afforded
13a-I and 13a-T in high yield (entry 2). Various arylzinc reagents
were also used in this reaction (entries 3-6). In each reaction of
1g, the aryl group was introduced from the same side of
π-allylnickel complex 2g in regio- and stereoselective manners
to afford an arylative carboxylation product in good yield.
a Isolated yield based on Ni(cod)2. b The ratio was determined by
1H NMR analysis. c Time 1 ) 6 h; time 2 ) 2 h. d Time 1 ) 4 h; time
2 ) 2 h. e The detailed characterization was done after separation by
silica gel column chromatography. f Time 1 ) 4 h; time 2 ) 1 h. g Time
1 ) 6 h; time 2 ) 1 h.
In conclusion, we have demonstrated that nickel-promoted
dicarboxylation or arylative carboxylation of 1,3-dienes proceeded
in a highly stereoselective manner in the presence of Me2Zn or
arylzinc reagents. The reaction could be carried out under very
mild conditions in a short reaction time with very simple
procedures. Further studies on the development to a catalytic
process are in progress in our laboratory.
Acknowledgment. This work was supported by a Grant-in-Aid for
Scientific Research (No. 12771345) from the Japan Society for the
Promotion of Science (JSPS).
Supporting Information Available: Information on typical proce-
dures for carboxylations, procedures for determination of the stereo-
chemistry of 7g and 13g, and spectral data for substrates and products
(PDF). This material is available free of charge via the Internet at
http://pubs.acs.org.
(8) Hoberg and Behr reported some examples of nickel-promoted dicar-
boxylation of 1,3-diene, which proceeded via direct insertion of second CO2
into the initially formed complex corresponding to 2.6f,h
(9) Tamaru reported that π-allylpalladium complexes are converted to
allyzincs in the presence of Et2Zn. A similar process might convert 8 to allyzinc
I, which then could undergo addition to CO2. However, he has shown that
the addition of the corresponding allyzincs to carbonyl compounds proceeds
in the same face of zinc metal (syn-attack). Thus, this pathway should be
excluded. (a) Tamaru, Y.; Tanaka, A.; Yasui, K.; Goto, S.; Tanaka, S. Angew.
Chem., Int. Ed. Engl. 1995, 34, 787.
JA004004F
(10) It is not clear yet why transmetalation of 2g affords different product
depending on the organozinc reagent used. In nickel and palladium complexes,
a reductive elimination between two Csp2 centers or a Csp2 center and a Csp3
center is generally faster than a reductive elimination between two Csp3 centers.
These facts may cause the different reaction pathways. (a) Yamamoto, A.;
Ozawa, F. Nippon Kagaku Kaishi 1987, 773. (b) Giovannini, R.; Stu¨demann,
T.; Devasagayaraj, A.; Dussin, G.; Knochel, P. J. Org. Chem. 1999, 64, 3544.
(c) Loar, M. K.; Stille, J. K. J. Am. Chem. Soc. 1981, 103, 4174. (d) Kurosawa,
H.; Ohnishi, H.; Emoto, M.; Kawasaki, Y.; Murai, S. J. Am. Chem. Soc. 1988,
110, 6272.