Cobalt-catalyzed coupling reaction of alkyl halides with allylic grignard reagents

Article abstract of DOI:10.1002/1521-3773(20021104)41:21<4137::AID-ANIE4137>3.0.CO;2-0

Facile construction of quaternary carbon centers: The cobalt-catalyzed coupling reaction of not only primary and secondary but also tertiary alkyl halides with allylic Grignard reagents proceeds smoothly (see scheme; dppp = 1,3-bis(diphenylphosphanyl)prop

Full text of DOI:10.1002/1521-3773(20021104)41:21<4137::AID-ANIE4137>3.0.CO;2-0

COMMUNICATIONS
structures were solved by direct methods and refined by full-matrix least-
aryl and vinyl halides. 2) b-Hydride elimination of the
alkylpalladium and -nickel compound is problematic. Thus,
novel and efficient methods for alkyl±alkyl coupling are
2
squares on F . The cyanide group in 2 is disordered over a site of symmetry
1
1
2
, and the independent carbon atom is represented by =
2
C þ
2
= N.
CCDC-184663 (1) and CCDC-184664 (2) contain the supplementary
crystallographic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/conts/retrieving.html (or from the Cam-
bridge Crystallographic Data Centre, 12, Union Road, Cambridge
CB21EZ, UK; fax: (þ 44)1223-336-033; or deposit@ccdc.cam.ac.uk).
[2,3]
currently under intense investigation.
We are interested in cobalt-catalyzed reactions[4,5] and
report herein the cobalt-catalyzed cross-coupling reaction of
alkyl halides with allylic Grignard reagents. Allylation of
various alkyl halides proceeds smoothly, and even quaternary
carbon atoms have become readily accessible by transition-
metal-catalyzed coupling reactions.
Received: July 24, 2002 [Z19812]
[
1] a) G.-C. Guo, Q.-G. Wang, G.-D. Zhou, T. C. W. Mak, Chem. Commun.
998, 339 ± 340; b) G.-C. Guo, G.-D. Zhou, Q.-G. Wang, T. C. W. Mak,
Angew. Chem. 1998, 110, 652 ± 654; Angew. Chem. Int. Ed. 1998, 37,
1
Allylmagnesium chloride (1.0m solution in THF, 1.5 mmol)
was added to a solution of 2-bromo-2-methyldecane (1a;
6
1
30 ± 632; c) G.-C. Guo, G.-D. Zhou, T. C. W. Mak, J. Am. Chem. Soc.
999, 121, 3136 ± 3141.
0
.50 mmol) in THF in the presence of [CoCl (dppp)]
2
(
0.05 mmol) at ꢀ208C (Scheme 1; dppp ¼ 1,3-bis(diphenyl-
[2] Q.-M. Wang, T. C. W. Mak, J. Am. Chem. Soc. 2000, 122, 7608 ± 7609.
[3] Q.-M. Wang, T. C. W. Mak, J. Am. Chem. Soc. 2001, 123, 1501 ± 1502.
[4] a) Q.-M. Wang, T. C. W. Mak, J. Am. Chem. Soc. 2001, 123, 7594 ± 7600;
b) Q.-M. Wang, T. C. W. Mak, Angew. Chem. 2001, 113, 1164 ± 1167;
Angew. Chem. Int. Ed. 2001, 40, 1130 ± 1133.
phosphanyl)propane). Stirring for 2 h at ꢀ208C provided the
cat. [CoCl2(dppp)]
CH2=CHCH2MgCl
+
[
5] a) Q.-M. Wang, T. C. W. Mak, Chem. Commun. 2001, 807 ± 808; b) Q.-
M. Wang, H. K. Lee, T. C. W. Mak, New. J. Chem. 2002, 26, 513 ± 515.
6] a) M. A. Omary, T. R. Webb, Z. Assefa, G. E. Shankle, H. H. Patterson,
Inorg. Chem. 1998, 37, 1380 ± 1386; b) G.-C. Guo, T. C. W. Mak, Angew.
Chem. 1998, 110, 3296 ± 3299; Angew . Chem. Int. Ed. 1998, 37, 3183 ±
n-C8H17
Br
n-C8H17
8 17
n-C H
THF, –20 °C
1
a
2a
3a
[
Scheme 1. Cobalt-catalyzed cross-coupling reaction of alkyl halide 1a with
allylmagnesium chloride.
3
186; c) C.-M. Che, M.-C. Tse, M. C.-W. Chan, K.-K. Cheung, D. L.
Phillips, K.-H. Leung, J. Am. Chem. Soc. 2000, 122, 2464 ± 2468.
7] a) P. Pyykkˆ, Chem. Rev. 1997, 97, 597 ± 636; b) M. Jansen, Angew.
Chem. 1987, 99, 1136 ± 1149; Angew . Chem. Int. Ed. Engl. 1987, 26,
allylated product 2a, which contains a quaternary carbon
center (90% yield), and 3a (8%). No allylated product was
[
1
098 ± 1110.
obtained when the [CoCl (dppp)] catalyst was omitted. The
2
yield of 2a was lower when 1,4-bis(diphenylphosphanyl)bu-
tane (DPPB), 1,2-bis(diphenylphosphanyl)ethane (DPPE),
and bis(diphenylphosphanyl)methane (DPPM) were em-
ployed in place of DPPP. Reaction at ꢀ408C led to recovery
of 1a, whereas reaction at 08C resulted in a lower ratio of 2a/
Cobalt-Catalyzed Coupling Reaction of Alkyl
Halides with Allylic Grignard Reagents**
3
a (82:18).
Allylation of a variety of alkyl halides proceeded smoothly,
Takashi Tsuji, Hideki Yorimitsu, and
Koichiro Oshima*
although tuning of reaction conditions was necessary for the
different substrates (Table 1). Benzylic allylation of 1d
required DPPE in place of DPPP to attain a satisfactory
result. Primary and secondary bromides were less reactive.
Instead, use of alkyl iodides such as 1 g-I led to high yields at
ꢀ408C. It is worth noting that halides 1h, 1h-I, and 1i-I, which
have alkoxy groups at the b position to the halide atom,
participated in the allylation.
Other allylic Grignard reagents were available for this
reaction (Scheme 2). Regioselective coupling was observed to
yield methyl-branched product 5b upon treatment of 1 g-I
with crotyl Grignard reagent. Unfortunately, reaction of
prenyl Grignard reagent was unsuccessful.
Nickel- and palladium-catalyzed cross-coupling reactions of
organic halides with organometallic reagents is one of the
most versatile carbon±carbon bond-forming reactions in
organic synthesis.[ In most cases, aryl and vinyl halides are
1]
2
2
2
2
employed as organic halides, yielding sp ±sp, sp ±sp , and sp ±
3
3
sp linkages. The connection of two sp carbon atoms under
transition metal catalysis is also important, and a variety of
retrosynthetic analyses are conceivable in which an arbitrary
carbon±carbon bond in an alkyl chain is cleaved. However,
coupling with alkyl halides is difficult for two main reasons: 1)
Oxidative addition of alkyl halides is much slower than that of
Substrates having proper carbon±carbon double bonds
were then subjected to the cobalt-catalyzed allylation
Scheme 3). Consequently, tandem cyclization/allylation oc-
[
*] Prof. Dr. K. Oshima, T. Tsuji, Dr. H. Yorimitsu
Department of Material Chemistry
Graduate School of Engineering
Kyoto University
(
curred, thereby affording 3-butenyl-substituted lactones after
Jones oxidation of the cyclic acetals. For example, iodoacetal
7c was converted to lactone 9c bearing a quaternary center,
and cyclization of 7d provided the trans isomer 9d exclusively.
Interestingly, treatment of 7e with the allyl Grignard
reagent CH ¼CHCH MgCl in the presence of [CoCl (dppp)]
Yoshida, Sakyo-ku, Kyoto 606±8501 (Japan)
Fax : (þ 81)75±753±4863
E-mail: oshima@fm1.kuic.kyoto-u.ac.jp
[
**] This work was supported by Grants-in-Aid for Scientific Research
Nos. 12305058 and 10208208) from the Ministry of Education,
2
2
2
(
furnished the ring-opening product 9e (Scheme 4). Given that
intramolecular carbocobaltation proceeds to yield cyclopro-
pylmethylcobalt species, b-carbon elimination would provide
a route to 9e. However, b-carbon elimination seems unlikely
Culture, Sports, Science and Technology, Government of Japan. H.Y.
acknowledges JSPS for financial support.
Supporting information for this article is available on the WWW under
http://www.angewandte.org or from the author.
Angew. Chem. Int. Ed. 2002, 41, No. 21
¹ 2002 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0044-8249/02/4121-4137 $ 20.00+.50/0
4137

COMMUNICATIONS
Table 1. Cobalt-catalyzed allylation of alkyl halides.
cat. [CoCl2(dppp)]
CH =CHCH MgCl
9
e
n-C4H9O
O
O
2
2
O
cat. [CoCl2(dppp)]
71%
CH2=CHCH2MgCl
THF, –40 °C
R
R–X
I
THF, temp.
7e
then CrO3/acetone
1
2
CH3
1
Temperature
8C]
Yield of 2
[%]
[
O
O
n-C4H9O
n-C4H9O
1
b
ꢀ20
83
1
0
11
¼CHCH
1 [
c
a]
0
76[b]
Scheme 4. Cobalt-catalyzed reaction of 7e with CH
the ring-opening product 9e.
2
2
MgCl to give
1
d
ꢀ20
73[c]
1)
2)
3)
R
R–X
R •
R' •
R–Co(allyl)
1
1
e
0
57
84
Scheme 5. Proposed mechanism for the catalytic reaction: 1) single-
electron transfer from cobalt complex; 2) recombination of alkyl radical
and cobalt complex; 3) reductive elimination.
f
ꢀ20
1
1
g
g-I
0
ꢀ40
30
82
cat. [CoCl2L*]
MgCl
CH3
Ar
CH3
Ar
1
a-Cl
20
31
t-C4H9
t-C4H9
1d
1
1
h
h-I
0
ꢀ40
49
82
2d
12
HO
Ph2P
PPh2
Ar = p-CH3OC6H4 –20 °C, 70%, 14%ee
–40 °C, 57%, 15%ee
76[d]
1
i-I
ꢀ40
L* : (–)-CHIRAPHOS
–78 °C, 49%, 22%ee
Scheme 6. Cobalt-catalyzed asymmetric allylation of 1d.
[
8
a] trans/cis ¼ 87/13. [b] trans/cis ¼ 82/18. [c] DPPE was used. [d] trans/cis ¼
6/14.
because b-hydride and b-alkoxy eliminations were minor
processes in the reactions of 1. Alternatively, the existence of
radical intermediates 10 and 11 can account for the ring
opening.[
6]
MgCl
MgCl
R
R
Scheme 5 shows schematically a proposed mechanism for
the catalytic reaction in analogy with the results of previous
reports.[ Namely, the oxidative addition proceeds via a
single-electron transfer from an electron-rich allylcobalt
complex to the alkyl halide. p-Allyl ligands may prevent the
formation of the vacant coordination sites necessary for b-
elimination, which enables allylation of tertiary and secon-
dary alkyl halides and alkyl halides having b-alkoxy groups.
1
g-I
6
9%
2%
4
4]
R
+
1
g-I
8
5a
5
b
b
3
: 97
MgCl
R
+
R
1
g-I
19%
Finally,
asymmetric
allylation
was
investigated
6a
6
4
7 : 53
[7,8]
(
Scheme 6). Treatment of 1d with allylmagnesium chloride
Scheme 2. R ¼ Ph(CH
2
)
3
. Conditions: cat. [CoCl
2
(dppp)], THF, ꢀ408C.
in the presence of [CoCl {(ꢀ)-chiraphos}] at ꢀ208C afforded
2
2
d. Hydroboration of 2d followed by usual oxidation
provided 12 in 70% yield and 14% ee. When the reaction
was carried out at a lower temperature (ꢀ788C), the
enantiomeric excess increased to 22%. The cobalt-catalyzed
asymmetric allylation provides a novel utility of transition-
metal-catalyzed radical reactions.
R1
R1
cat. [CoCl (dppp)]
CH2=CHCH2MgCl
2
n-C4H9O
O
n-C4H9O
O
R2
R2
R3
I
THF, –40 °C
7
8
9
In summary, [CoCl (dppp)] effectively catalyzes the cross-
R3
R3
2
R3
coupling reaction of alkyl halides with allylic Grignard
reagents. Not only primary alkyl halides but also secondary
and tertiary alkyl halides undergo allylation, in the latter case
to give quaternary carbon centers.
R1
R2
R3 Yield of 9 [%]
7
7
7
7
a
H
CH3
H
CH3
H
H
H
77
100
98
R1
R2
O
O
b
c
d
H
CH3
H
Experimental Section
77
R3
n-C5H11
H
R3
Anhydrous cobalt(ii) chloride (7.0 mg, 0.050 mmol) was placed in a 20 mL
Scheme 3. Cobalt-catalyzed reaction of iodoacetals 7 to give lactones 9.
¹ 2002 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
flask and was heated with a hair dryer in vacuo for 2 min. After the color of
4138
0044-8249/02/4121-4138 $ 20.00+.50/0
Angew. Chem. Int. Ed. 2002, 41, No. 21

COMMUNICATIONS
the cobalt salt became blue, DPPP (25 mg, 0.060 mmol) and anhydrous
THF (1.0 mL) were sequentially added under argon. The mixture was
stirred for 10 min at room temperature. 2-Bromo-2-methyldecane (1a,
Distal Cu Ion Protects Synthetic Heme/Cu
Analogues of Cytochrome Oxidase against
Inhibition by CO and Cyanide**
0
.12 g, 0.50 mmol) and allylmagnesium chloride (1.0m solution in THF,
1.5 mL, 1.5 mmol) were successively added dropwise to the reaction
James P. Collman,* Roman Boulatov,
Irina M. Shiryaeva, and Christopher J. Sunderland
mixture at ꢀ208C. While the Grignard reagent was being added, the
mixture turned reddish-brown. After being stirred for 2 h at ꢀ208C, the
4
reaction mixture was poured into saturated NH Cl solution, and the
products were extracted with ethyl acetate (20 mL î 2). The combined
organic layer was dried over Na SO and concentrated. Purification of the
crude oil by silica gel column chromatography (hexane) provided 4,4-
Cytochrome c oxidase (CcO) is the enzyme that makes
aerobic metabolism possible by catalyzing the final step in the
respiratory electron-transfer chain–a four-electron (4e),
2
4
dimethyl-1-dodecene (2a) and 2-methyl-1-decene (3a) (94 mg, 90% and
1
four-proton (4H ) reduction of O to water.[1,2] Catalysis
þ
8
% yields, respectively, as determined by H NMR spectroscopy).
2
[3]
proceeds at the heterobimetallic heme/Cu site (Figure 1).
B
Received: August 8, 2002 [Z19929]
The Fe center is the site of O binding, and reduction of O is
2
2
I
coupled to oxidation of Cu , at least under single-turnover
[
1] a) Metal-Catalyzed Cross-Coupling Reactions (Eds.: F. Diederich, P. J.
Stang), Wiley-VCH, Weinheim, 1998; b) J. Organomet. Chem. (Special
issue, Eds.: K. Tamao, T. Hiyama, E. Negishi) 2002, 653(1±2); c) J.
Tsuji, Palladium Reagents and Catalysts. Innovations in Organic
Synthesis, Wiley, Chichester, 1996; d) Comprehensive Organic Syn-
thesis, Vol. 3 (Eds.: B. M. Trost, I. Fleming, C. H. Heathcock),
Pergamon Press, New York, 1991, chapt. 2.1±2.5.
2] Several groups reported interesting sp ±sp couplings of primary alkyl
halides with organometallic reagents. See: a) R. Giovannini, T.
St¸demann, G. Dussin, P. Knochel, Angew. Chem. 1998, 110, 2512 ±
B
conditions.[
4,5]
One of the poorly understood questions
regarding the structure±activity relationship at the heme/
Cu site is how the heme reactivity is affected by the closely
B
positioned, positively charged CuB center. Such effects are
expected to manifest themselves in an attenuated affinity of
the Fe center for small molecules. Among these, CO and the
3
3
[
ꢀ
ꢀ
ions CN and N , are of particular interest, because the
3
ꢀ
ꢀ
cytotoxicity of the CN and N ions arises from the inhibition
of CcO and resultant respiratory shutdown,[ and CO is an
endogenous inhibitor of ferrohemes. The mode of CN ion
3
2
515; Angew. Chem. Int. Ed. 1998, 37, 2387 ± 2390; b) R. Giovannini, T.
7]
St¸demann, A. Devasagayaraj, G. Dussin, P. Knochel, J. Org. Chem.
ꢀ
1
999, 64, 3544 ± 3553; c) A. E. Jensen, P. Knochel, J. Org. Chem. 2002,
6
7, 79 ± 85; d) M. R. Netherton, C. Dai, K. Neusch¸tz, G. C. Fu, J. Am.
binding to the heme/Cu site and the effect(s) of Cu on such
B
B
Chem. Soc. 2001, 123, 10099 ± 10100; e) K. Park, K. Yuan, W. J. Scott, J.
Org. Chem. 1993, 58, 4866 ± 4870; f) J. Terao, H. Watanabe, A. Ikumi,
H. Kuniyasu, N. Kambe, J. Am. Chem. Soc. 2002, 124, 4222 ± 4223; also
see recent reviews: g) T.-Y. Luh, M. Leung, K.-T. Wong, Chem. Rev.
[8]
binding remain controversial. Likewise, contradictory re-
sults have been reported for differences in the CO affinities of
[9,10]
the wild-type and Cu -free mutants of terminal oxidases.
B
2
000, 100, 3187 ± 3204; h) D. J. Cµrdenas, Angew. Chem. 1999, 111,
Previously, we demonstrated that the biomimetic com-
3
201 ± 3203; Angew. Chem. Int. Ed. 1999, 38, 3018 ± 3020.
plexes shown in Figure 1b quantitatively reproduce the key
[
[
[
3] Coupling reaction of t-C
4
H
9
-I with 9-alkyl-9-BBN: a) T. Ishiyama, S.
[6,11]
reactivity of the heme/Cu site
and thus allow the study of
B
Abe, N. Miyaura, A. Suzuki, Chem. Lett. 1992, 691 ± 694; coupling of 2-
bromohexane with two alkyl Grignard reagents: b) J. G. Donkervoort,
J. L. Vicario, J. T. B. H. Jastrzebski, R. A. Gossage, G. Cahiez, G.
van Koten, J. Organomet. Chem. 1998, 558, 61 ± 69.
questions that are not easily addressed by working with the
enzyme itself. Herein we report that the steady-state reduc-
4] a) K. Wakabayashi, H. Yorimitsu, K. Oshima, J. Am.
Chem. Soc. 2001, 123, 5374 ± 5375; b) Y. Ikeda, T.
Nakamura, H. Yorimitsu, K. Oshima, J. Am. Chem.
Soc. 2002, 124, 6514 ± 6515; c) T. Fujioka, T. Nakamura,
H. Yorimitsu, K. Oshima, Org. Lett. 2002, 4, 2257 ± 2259.
5] Other cobalt-catalyzed coupling reactions, see: a) G.
Cahiez, H. Avedissian, Tetrahedron Lett. 1998, 39,
6
159 ± 6162; b) H. Avedissian, L. Bÿrillon, G. Cahiez, P.
Knochel, Tetrahedron Lett. 1998, 39, 6163 ± 6166; c) Y.
Nishii, K. Wakasugi, Y. Tanabe, Synlett 1998, 67 ± 69;
d) M. Kharasch, E. K. Fields, J. Am. Chem. Soc. 1941, 63,
2
316 ± 2320; e) L. F. Elsom, J. D. Hunt, A. McKillop,
Organomet. Chem. Rev. A 1972, 8, 135 ± 152.
[
[
6] a) M. Newcomb in Radicals in Organic Synthesis, Vol. 1
(
Eds.: P. Renaud, M. Sibi), Wiley-VCH, Weinheim, 2001,
Figure 1. a) The heme/Cu
B
site of bovine cytochrome oxidase;[3] the C atoms are light gray
chapt. 3.1; b) M. Newcomb, S. Y. Choi, J. H. Horner, J.
Org. Chem. 1999, 64, 1225 ± 1231.
7] Asymmetric creation of quaternary carbon centers has
attracted much attention. For a review, see: a) K. Fuji,
Chem. Rev. 1993, 93, 2037 ± 2066; b) E. J. Corey, A.
and the N and O atoms are black, b) a synthetic heme/Cu
exogenous ligands and counterion are omitted.[
B
analogue in the reduced form;
6]
Guzman-Perez, Angew. Chem. 1998, 110, 402 ± 415; Angew. Chem. Int.
Ed. 1998, 37, 388 ± 401; c) J. Christoffers, A. Mann, Angew. Chem. 2001,
[
*] Prof. J. P. Collman, R. Boulatov, I. M. Shiryaeva, C. J. Sunderland
Department of Chemistry
Stanford University
1
13, 4725 ± 4732; Angew. Chem. Int. Ed. 2001, 40, 4591 ± 4597.
[
8] Enantioselective radical reactions were summarized. See: M. P. Sibi,
N. A. Porter, Acc. Chem. Res. 1999, 32, 163 ± 171.
Stanford CA 94305 (USA)
Fax : (þ 1)650-725-0259
E-mail: jpc@stanford.edu
[
**] This work was supported by NIH and a Stanford Graduate Fellowship
R.B.).
(
Supporting information for this article is available on the WWW under
http://www.angewandte.org or from the author.
Angew. Chem. Int. Ed. 2002, 41, No. 21
¹ 2002 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
0044-8249/02/4121-4139 $ 20.00+.50/0
4139