Ni(0)-promoted hydroxycarboxylation of 1,2-dienes by reaction with CO 2 and O2

Article abstract of DOI:10.1021/ol070038h

Figure presented A novel method for the preparation of hydroxy carboxylic acid derivatives has been developed by O₂-oxidation of π-allylnickel intermediates generated by Ni(0)-mediated coupling of 1,2-dienes with CO₂.

Full text of DOI:10.1021/ol070038h

ORGANIC
LETTERS
2
007
Vol. 9, No. 7
251-1253
Ni(0)-Promoted Hydroxycarboxylation of
,2-Dienes by Reaction with CO and O
1
1
2
2
Masao Aoki, Sawa Izumi, Motomu Kaneko, Kazutoshi Ukai, Jun Takaya, and
Nobuharu Iwasawa*
Department of Chemistry, Tokyo Institute of Technology, O-okayama, Meguro-ku,
Tokyo 152-8551, Japan
niwasawa@chem.titech.ac.jp
Received January 6, 2007
ABSTRACT
2
A novel method for the preparation of hydroxy carboxylic acid derivatives has been developed by O -oxidation of π-allylnickel intermediates
generated by Ni(0)-mediated coupling of 1,2-dienes with CO
2
.
π-Allylnickel complexes have been recognized as a useful
reagent for the carbon-carbon bond formation due to their
unique reactivities, and there have been extensive studies
In this paper, we report that oxidation of π-allylnickel
intermediates, generated by oxidative coupling of 1,2-dienes
and carbon dioxide, with molecular oxygen proceeds smoothly
and cleanly to afford synthetically useful hydroxy carboxylic
acid derivatives in good yield.
1
on their reaction with various organic halides, carbonyl
2
compounds, alkynes, organometallics, etc. However, only
a few examples have been reported so far concerning the
reaction of π-allylnickel complexes with molecular oxygen,
and no synthetically useful transformation has been realized
utilizing such oxidation of π-allylnickel intermediates.
During the study on the use of bis(amidine) ligand for the
Ni(0)-mediated oxidative coupling of unsaturated molecules
3,4
5
,6
such as alkynes and 1,2-dienes with CO
examine the reaction of cyclic 1,2-diene, cyclonona-1,2-diene
, for this reaction. Thus, cyclonona-1,2-diene 1 was added
dropwise over 1 h to a THF solution of Ni(cod) and a bis-
amidine) 7 under a CO atmosphere at 0 °C. After 2 h, the
2
,
we happened to
1
(
1) (a) Heimbach, P.; Jolly, P. W.; Wilke, G. AdV. Organomet. Chem.
2
1
970, 8, 29. (b) Baker, R. Chem. ReV. 1973, 73, 487. (c) Billington, D. C.
(
2
Chem. Soc. ReV. 1985, 14, 93. (d) Krysan, D. J. In ComprehensiVe
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G.,
Eds.; Elsevier Science Ltd.: Oxford, UK, 1995; Vol. 12, p 959. (e) Modern
Organonickel Chemistry; Tamaru, Y., Ed.; Wiley-VCH: Weinheim,
Germany, 2005. (f) Billington, D. C. In ComprehensiVe Organic Synthesis;
Trost, B. M., Fleming, I., Eds.; Pergamon Press: Oxford, 1991; Vol. 3, p
(3) For reactions of σ- or π-allyl complexes with molecular oxygen, see;
(a) Julia, M.; Lauron, H.; Verpeaux, J.-N. J. Organomet. Chem. 1990, 387,
365. (b) Dible, B. R.; Sigman, M. S. J. Am. Chem. Soc. 2003, 125, 872. (c)
Dible, B. R.; Sigman, M. S. Inorg. Chem 2006, 45, 8430.
4
23.
2) (a) Reference 1c and references cited therein. (b) Hegedus, L. S.;
(4) For formation of oxygenated compounds as side products, see: Sato,
Y.; Takanashi, T.; Hoshiba, M.; Mori, M. Tetrahedron Lett. 1998, 39, 5579.
(5) Aoki, M.; Kaneko, M.; Izumi, S.; Ukai, K.; Iwasawa, N. Chem.
Commun. 2004, 2568.
(
Thompson, D. H. P. J. Am. Chem. Soc. 1985, 107, 5663. (c) Johnson, J.
R.; Tully, P. S.; Mackenzie, P. B.; Sabat, M. J. Am. Chem. Soc. 1991, 113,
6
172. (d) Grisso, B. A.; Johnson, J. R.; Mackenzie, P. B. J. Am. Chem.
(6) For examples of Ni(0)-promoted reaction of 1,2-dienes with CO2,
see: (a) Hoberg, H.; Oster, B. W. J. Organomet. Chem. 1984, 266, 321.
(b) Sasaki, Y. J. Mol. Catal. 1989, 54, L9. (c) D e´ rien, S.; Clinet, J.-C.;
Du n˜ ach, E.; P e´ richon, J. Synlett 1990, 361. (d) D e´ rien, S.; Clinet, J.-C.;
Du n˜ ach, E.; P e´ richon, J. Tetrahedron 1992, 48, 5235. (e) Takimoto, M.;
Kawamura, M.; Mori, M. Org. Lett. 2003, 5, 2599. (f) Takimoto, M.;
Kawamura, M.; Mori, M. Synthesis 2004, 791. (g) Takimoto, M.; Kawa-
mura, M.; Mori, M.; Sato, Y. Synlett 2005, 2019.
Soc. 1992, 114, 5160. (e) Kobayashi, Y.; Takahisa, E.; Usmani, S. B.
Tetrahedron Lett. 1998, 39, 597. (f) Oppolzer, W. Angew. Chem., Int. Ed.
Engl. 1989, 28, 38. (g) Llebaria, A.; Mor e´ to, J. M. J. Organomet. Chem.
1
1
993, 451, 1. (h) Garc ´ı a-G o´ mez, G.; Mor e´ to, J. M. J. Am. Chem. Soc. 1999,
21, 878. (i) Nadal, M. L.; Bosch, J.; Vila, J. M.; Klein, G.; Ricart, S.;
Mor e´ to, J. M. J. Am. Chem. Soc. 2005, 127, 10476. (j) Ikeda, S. Acc. Chem.
Res. 2000, 33, 511.
1
0.1021/ol070038h CCC: $37.00
© 2007 American Chemical Society
Published on Web 03/07/2007

reaction was quenched with 1 M HCl for protonolysis of
7
π-allylnickel intermediate 2, and the crude product was
Table 1. Effect of Ligand
treated with trimethylsilyldiazomethane to convert carboxylic
acids to the corresponding methyl esters. Purification of the
crude product revealed that the desired R,â-unsaturated
carboxylic ester 6 was not produced at all, but that an
unexpected â-hydroxy carboxylic acid methyl ester 5 was
obtained as a single isomer albeit in low yield (Scheme 1).
entry
ligand
DBUb
TMEDA
bis(amidine) 7
bipy
yield (%)
a
1
2
3
4
5
7
a
a
a
14
Scheme 1. Reaction of π-Allylnickel Intermediate with
c
63
61
68
Molecular Oxygen
dtbpy
a
Cyclonona-1,2-diene 1 was added dropwise over 1 h. b 2.1 equiv of
DBU was used. c Yield of the hydroxy carboxylic acid corresponding to 5.
particular, the reaction with dtbpy proceeded smoothly
without the necessity of adding the 1,2-diene 1 slowly.
Furthermore, it was found that the temperature of the
oxidation step had a profound effect on this reaction. Thus,
when the oxygenation reaction was carried out at room
temperature, the yield of the desired hydroxy methyl ester
was low, and instead a dimer product 8 was obtained as a
major product (Table 2, entry 1). On the contrary, when the
This compound was the oxygenated product of the π-al-
lylnickel intermediate 2 produced by the oxidative coupling
2
of the 1,2-diene 1 and CO , and the oxygenation seemed to
Table 2. Effect of Temperature
be caused by molecular oxygen in the air during acidic
8
workup. As the reaction enables introduction of both
carboxy and hydroxy groups onto allenic compounds, we
decided to examine this novel oxygenation reaction in more
detail.
Careful analysis of the reaction revealed that the initial
product formed after acidic workup was peroxide 3, and then
it was converted to peroxy lactone 4 slowly. As these
intermediates appeared to be unstable and needed to be
reduced for producing â-hydroxycarboxylic acid, we first
examined the procedure for the reductive workup. Conse-
quently, it was found that the use of dimethyl sulfide or
triphenylphosphine as a reductant gave good results. Due to
the ease of removal of excess reagent and its oxidized
product, we decided to employ dimethyl sulfide as a
reductant for further examination.
Screening of solvents, ligands, temperature, oxidants, etc.
revealed that a dramatic effect of ligand on the yield of the
product was observed in this reaction (Table 1). Thus, when
temperature of the oxidation step was lowered to -78 °C,
the formation of the dimer product 8 was suppressed.
Although the mechanism of the dimer formation has not been
made clear, dimerization occurred competitively with the
oxygenation reaction and was suppressed at lower temper-
ature. Furthermore, when the oxygenation reaction was done
TMEDA or DBU, a good ligand for Ni(0)-mediated coupling
9
of CO
2
with unsaturated compounds, was employed as
ligand, the yield of the hydroxylated methyl ester was rather
10
low. On the contrary, use of bipy, dtbpy(4,4′-di-tert-butyl-
,2′-bipyridine), or bis(amidine) 7 gave good results. In
2
(
9) (a) Burkhart, G.; Hoberg, H. Angew. Chem., Int. Ed. Engl. 1982, 21,
(
7) We are not certain whether this intermediate takes the form of the
76. (b) Hoberg, H.; Peres, Y.; Milchereit, A. J. Organomet. Chem. 1986,
307, C38. (c) Saito, S.; Nakagawa, S.; Koizumi, T.; Hirayama, K.;
Yamamoto, Y. J. Org. Chem. 1999, 64, 3975. (d) Takimoto, M.; Mori, M.
J. Am. Chem. Soc. 2001, 123, 2895.
π-allyl or σ-allyl complex; however, we just refer to π-allyl in the text for
the simplicity.
(8) In our previous work (ref 5), π-allylnickel intermediates formed by
oxidative coupling of monosubstituted 1,2-dienes and CO2 easily underwent
protonolysis by 1 M aq HCl at rt. The reactivity of π-allylnickel
intermediates appears to be dependent on the substitution pattern of 1,2-
dienes.
(10) (a) Hoberg, H.; Schaefer, D. J. Organomet. Chem. 1982, 236, C28.
(b) Papai, I.; Schubert, G.; Mayer, I.; Besenyei, G.; Aresta, M. Organo-
metallics 2004, 23, 5252. (c) Geyer, C.; Schindler, S. Organometallics 1998,
17, 4400.
1252
Org. Lett., Vol. 9, No. 7, 2007

be noted that protonolysis of the π-allyl intermediate is very
1
1
slow even at room temperature.
The following procedure was found to be optimal. The
,2-diene 1 was treated with CO in the presence of Ni(cod)
2
Table 3. Generality of Oxidative Reaction with Various
1
,2-Dienesa
1
2
and dtbpy at 0 °C for 2 h, and then excess HCl-MeOH was
added to the mixture at -78 °C under an Ar atmosphere.
The reaction mixture was exposed to an O
2
atmosphere for
2
h at this temperature, followed by reduction with dimethyl
sulfide. Finally, the crude hydroxy carboxylic acid was
esterified with trimethylsilyldiazomethane for the purpose
of facile purification to give the corresponding hydroxy
methyl ester.
The generality of the oxidation of π-allylnickel intermedi-
ates was examined with several substituted 1,2-dienes using
dtbpy as a ligand. As summarized in Table 3, this reaction
could be applied to monoalkyl- or aryl-substituted 1,2-dienes
1
0-12 to give a mixture of regioisomeric products. In both
cases, only the E-isomer was produced for the endo olefins
0b-12b. 1,1-Disubstituted 1,2-dienes 13 and 14 also
1
afforded the desired hydroxy carboxylic acid or its methyl
ester in moderate to good yield. In these cases, exo olefins
13a and 14a were obtained as a major regioisomer. Further-
more, acyclic 1,3-disubstituted 1,2-dienes 15 and 16 as well
as 13-membered cyclic 1,2-diene 17 were applicable to this
reaction. Although regiochemical and, in some cases, geo-
metrical control of the oxygenation reaction is not necessarily
good, this method enables introduction of two functional
groups onto 1,2-dienes under mild reaction conditions simply
2 2
by using CO and O and would afford a concise method
for the preparation of hydroxy carboxylic acid derivatives.
In conclusion, preparation of hydroxy carboxylic acid
derivatives utilizing novel oxidation with molecular oxygen
of the π-allylnickel intermediates generated by Ni(0)-
mediated coupling of 1,2-dienes with CO
Synthetically useful hydroxy carboxylic acid derivatives were
obtained in good yield starting from 1,2-dienes, CO , and
. Further investigation on the mechanism of this reaction
is in progress.
2
was achieved.
2
O
2
Acknowledgment. This research was partly supported by
a Grant-in-Aid for Scientific Research from the Ministry of
Education, Culture, Sports, Science, and Technology of
Japan.
a
1,2-Dienes 11, 12, 14, and 15 were added dropwise over 1 h.
without adding HCl-MeOH at -78 °C, an epoxide 9 was
obtained along with the desired hydroxy methyl ester. Thus,
it is important for this reaction to do the oxygenation reaction
after the treatment with acid at low temperature. It should
Supporting Information Available: Preparative methods
and spectral and analytical data of compounds 10a,b, 11b,
13, 13a,b, 14a,b, 15a,b, 16a, and 17a. This material is
available free of charge via the Internet at http://pubs.acs.org.
(11) It is necessary to heat the π-allylnickel intermediate 2 in refluxing
HCl-MeOH to cause the protonolysis of this intermediate.
OL070038H
Org. Lett., Vol. 9, No. 7, 2007
1253