Rhodium-catalysed substitutive arylation of cis-allylic diols with arylboroxines

Article abstract of DOI:10.1039/b612710j

Substitutive arylation of cis-allylic diols occurs upon treatment with arylboroxines in the presence of a rhodium(i) catalyst; the reaction proceeds through the addition of an intermediate arylrhodium(i) species across the carbon-carbon double bond and su

Full text of DOI:10.1039/b612710j

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Rhodium-catalysed substitutive arylation of cis-allylic diols with
arylboroxines{
Tomoya Miura, Yusuke Takahashi and Masahiro Murakami*
Received (in Cambridge, UK) 4th September 2006, Accepted 20th October 2006
First published as an Advance Article on the web 8th November 2006
DOI: 10.1039/b612710j
Substitutive arylation of cis-allylic diols occurs upon treatment
with arylboroxines in the presence of a rhodium(I) catalyst; the
reaction proceeds through the addition of an intermediate
arylrhodium(I) species across the carbon–carbon double bond
and subsequent b-oxygen elimination.
The rhodium-catalysed addition of organoborons to alkenes and
alkynes has emerged as a powerful method for the construction of
carbon–carbon bonds.1 Although alkenes are generally less
reactive than alkynes, activated examples, such as electron-
deficient2 and strained3 alkenes, act as good acceptors of
organorhodium(I) intermediates. In aqueous media, styrene
derivatives also react with organoborons.4 We have been trying
to expand the scope of rhodium-catalysed addition and have
found a new example of the alkene addition reaction. Herein, we
report the rhodium-catalysed substitutive arylation of cis-allylic
diols with arylboroxines.
Scheme 1 A plausible mechanism for the catalysed addition reaction.
A solution of cis-but-2-ene-1,4-diol (1a) and phenylboroxine (2a,
3.0 equiv. of B) in 1,4-dioxane (0.1 M) was stirred in the presence
of [Rh(OH)(cod)]2 (5 mol% Rh, cod = cycloocta-1,5-diene) at
room temperature for 12 h. After chromatography, 2-phenylbut-3-
en-1-ol (3aa) was isolated in 65% yield, together with a small
amount of 3-phenylbut-3-en-1-ol (4aa, ca. 3%; eqn. 1). Other
organoborons, like phenylboronic acid and its glycol ester, gave
lower yields.
1,2-addition across the carbon–carbon double bond of A,9 giving
the alkylrhodium(I) intermediate B. Subsequent b-oxygen elimina-
tion occurs to generate the major product 3aa. Another pathway is
also derived from B that leads to the minor product 4aa.
b-Hydride elimination and re-addition with the opposite regio-
chemistry gives the alkylrhodium(I) intermediate D. The following
b-oxygen elimination affords minor product 4aa. It is of note for B
that b-oxygen elimination predominates over b-hydride elimina-
tion.3e,10 This is in sharp contrast to the palladium-catalysed Heck-
type reaction of 1a with aryl halide, where organopalladium(II)
intermediate E undergoes b-hydride elimination rather than
b-oxygen elimination, leading to the formation of a 4-aryltetrahy-
drofuran-2-ol (Scheme 2).11,12
ð1Þ
A control experiment was carried out using trans-but-2-ene-1,4-
diol, which is unlikely to be transformed into the corresponding
cyclic arylboronic ester. The reaction was sluggish at room
temperature, giving only a trace amount of 3aa after 12 h. In
When 1a (0.16 mmol) was mixed with 2a (0.16 mmol, 3 equiv.
of B) in 1,4-dioxane-d8 (1 mL) in the absence of rhodium catalyst,
the spontaneous formation of cyclic arylboronic ester A5 via
1
transesterification was observed by H NMR.6 We assume the
stepwise pathways depicted in Scheme 1 for the reaction of 1a.7
Initially, cyclic arylboronic ester A is formed in situ from 1a and 2a.
Then, transmetalation of hydroxorhodium(I) with A generates a
phenylrhodium(I) species.8 The phenylrhodium(I) undergoes syn
Department of Synthetic Chemistry and Biological Chemistry, Kyoto
University, Katsura, Kyoto 615-8510, Japan.
E-mail: murakami@sbchem.kyoto-u.ac.jp; Fax: +81 75 383 2748;
Tel: +81 75 383 2747
{ Electronic supplementary information (ESI) available: Experimental
details and spectral data. See DOI: 10.1039/b612710j
Scheme 2 The palladium-catalysed Heck-type reaction of cis-allylic diol
1a with aryl halide.
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Table 1 Rhodium-catalysed substitutive arylation of cis-allylic diol
1a with arylboroxines or an alkenylboroxine 2a
Table 2 Asymmetric arylative addition catalysed by a rhodium(I)
complexa
Entry
2 (R)
3
Yield (%)b
Entry
1
2 (R)
Ligand
3
Yield (%)b ee (%)c
1
2
3
4
5
6
2b (4-Me–C6H4)
2c (4-F–C6H4)
2d (3-MeO–C6H4)
2e (3-Cl–C6H4)
2f (1-Naphthyl)
3ab
3ac
3ad
3ae
3af
3ag
69c
52c
81
1
2
3
4
5
a
1a 2a (Ph)
1a 2a (Ph)
1a 2d (3-MeO–C6H4)
1a 2f (1-Naphthyl)
1b 2d (3-MeO–C6H4)
8
9
9
9
9
3aa 55
3aa 68
3ad 62
3af 60d,e
3bd 57f
41
83
53
87
78
77c
81
22c,d
Unless otherwise noted, all reactions were carried out with 1
(0.55 mmol), 2 (0.92 mmol), [RhCl(C2H4)2]2 (5 mol% Rh), chiral
ligand (5.5 mol%) and KOH (0.28 mmol) in dioxane (5 mL) at 40 uC
a
Unless otherwise noted, all reactions were carried out with 1a
(0.55 mmol), 2 (0.55 mmol) and [Rh(OH)(cod)]2 (5 mol% Rh) in
dioxane (5 mL) at rt for 12–24 h. Isolated yield. 5 equiv. of B
b
c
b
c
for 2 d. Isolated yield. Determined by a Chiralcel OD-H column.
d
e
f
d
H2O (1.5 equiv.) was added. 60 uC. 100 uC.
was used. 60 uC.
Table 2, entry 2). The highest enantioselectivity was observed when
1-naphthylboroxine (2f) was used (87% ee; Table 2, entry 4).
Analogous reaction conditions were applied to cyclic allylic diol 1b
to give 3bd (78% ee; Table 2, entry 5).15
addition, no reaction occurred when cis-non-2-en-1-ol was used
as the substrate. These results indicate that formation of the
cyclic arylboronic ester A facilitates the 1,2-addition of a
phenylrhodium(I) species. The use of other substrates 5–7, which
were derived from cis-but-2-ene-1,4-diol, was also examined.
However, these substrates failed to participate in the substitutive
reaction.
In summary, we have developed a rhodium-catalysed addition
reaction of arylboroxines with cis-allylic diols, allowing the regio-
and stereoselective formation of 2-aryl-3-en-1-ols.16
A variety of arylboroxines and an alkenylboroxine 2 were
subjected to the substitutive arylation of cis-allylic diol 1a
(Table 1).13{ Both electron-donating and -withdrawing aromatic
substituents were suitably reactive (Table 1, entries 1–4). In the
case of sterically bulkier 1-naphthylboroxine (2f), the correspond-
ing product 3af was obtained in 81% yield (Table 1, entry 5).
However, alkenylboroxine 2g produced compound 3ag in only
22% yield (Table 1, entry 6).
This work was supported in part by a Grant-in-Aid for Young
Scientists (B) (no. 18750084) from the Ministry of Education,
Culture, Sports, Science, and Technology, Japan.
Notes and references
{ Representative procedure: To an oven-dried, Ar-purged flask was added
phenylboroxine (2a, 176.5 mg, 0.57 mmol, 3.0 equiv. of B) and
[Rh(OH)(cod)]2 (6.5 mg, 0.014 mmol, 5 mol% Rh). Then, a solution of
substrate 1a (48.9 mg, 0.56 mmol) in 1,4-dioxane (5 mL) was added. The
resulting reaction mixture was stirred for 12 h at room temperature. An
aqueous solution of 2 M NaOH (6 mL) was added and the aqueous layer
was extracted with diethyl ether (4 6 15 mL). The combined extracts were
dried over MgSO4. The solvent was removed under reduced pressure and
the residue purified by preparative thin-layer chromatography (hexane :
ethyl acetate = 5 : 3) to give the product 3aa (53.8 mg, 0.36 mmol) in 65%
yield.
We next examined the reaction with cyclic cis-allylic diol 1b.
When cis-cyclopent-4-ene-1,3-diol (1b) was treated with phenyl-
boroxine (2a, 5.0 equiv. of B) at 100 uC for 24 h, trans-2-phenyl-
cyclopent-3-en-1-ol (3ba, 46%) was obtained in a regio- and
stereoselective manner (eqn. 2). The reaction of 1b with
3-methoxyphenylboroxine (2d) gave the trans-isomer 3bd stereo-
selectively in 70% yield. The trans stereochemistry of the arylated
products can be explained by assuming that the syn 1,2-addition of
an arylrhodium(I) species across a carbon–carbon double bond
occurs from opposite sides of the hydroxyl groups and that
b-oxygen elimination proceeds in an anti fashion.10a
1 Reviews: (a) K. Fagnou and M. Lautens, Chem. Rev., 2003, 103, 169; (b)
T. Hayashi and K. Yamasaki, Chem. Rev., 2003, 103, 2829.
2 (a) M. Sakai, H. Hayashi and N. Miyaura, Organometallics, 1997, 16,
4229; (b) T. Hayashi, M. Takahashi, Y. Takaya and M. Ogasawara,
J. Am. Chem. Soc., 2002, 124, 5052; (c) R. Shintani, W.-L. Duan and
T. Hayashi, J. Am. Chem. Soc., 2006, 128, 5628 and references cited
therein.
ð2Þ
3 (a) K. Oguma, M. Miura, T. Satoh and M. Nomura, J. Am. Chem.
Soc., 2000, 122, 10464; (b) M. Lautens, C. Dockendorff, K. Fagnou and
A. Malicki, Org. Lett., 2002, 4, 1311; (c) M. Murakami and H. Igawa,
Chem. Commun., 2002, 390; (d) T. Miura and M. Murakami, Org. Lett.,
2005, 7, 3339; (e) T. Miura, T. Sasaki, T. Harumashi and M. Murakami,
J. Am. Chem. Soc., 2006, 128, 2516; (f) N.-W. Tseng, J. Mancuso and
M. Lautens, J. Am. Chem. Soc., 2006, 128, 5338.
4 M. Lautens, A. Roy, K. Fukuoka, K. Fagnou and B. Mart´ın-Matute,
J. Am. Chem. Soc., 2001, 123, 5358.
5 An authentic sample of ester A was prepared by reacting 1a with
phenylboronic acid in benzene in the presence of MgSO4 as a
dehydrating agent.
Since 2-aryl-3-en-1-ols are versatile synthons that can be further
manipulated in a stereo- and chemoselective way, the asymmetric
version of the substitutive arylation was briefly examined (Table 2).
In the case of (S)-BINAP (8), which is highly effective for the
rhodium-catalysed asymmetric addition of arylboronic acids to
electron-deficient alkenes,2b both the yield and the enantioselec-
tivity were modest (55% yield, 41% ee; Table 2, entry 1). The use of
chiral diene ligand 9, developed by Carreira et al.,14 improved both
the chemical yield and the enantioselectivity (68% yield, 83% ee;
6 N. Iwasawa, T. Kato and K. Narasaka, Chem. Lett., 1988,
1721.
596 | Chem. Commun., 2007, 595–597
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7 For the rhodium-catalysed cross-coupling of allyl alcohols with
arylboronic acid via a p-allylrhodium intermediate, see: G. W. Kabalka,
G. Dong and B. Venkataiah, Org. Lett., 2003, 5, 893.
E. Bernocchi, S. Cacchi and F. Marinelli, Tetrahedron, 1991, 47, 1525;
(d) S. Takano, K. Samizu and K. Ogasawara, Synlett, 1993, 393.
13 An excess amount of 2 was required to obtain a good yield, as is often
the case for rhodium-catalysed reactions using arylboronic acids.
14 (a) J.-F. Paquin, C. Defieber, C. R. J. Stephenson and E. M. Carreira,
J. Am. Chem. Soc., 2005, 127, 10850; Review: (b) F. Glorius, Angew.
Chem., Int. Ed., 2004, 43, 3364.
15 For the transition-metal catalysed desymmetrisation of cyclic allylic
diol derivatives, see: U. Piarulli, P. Daubos, C. Claverie,
C. Monti and C. Gennari, Eur. J. Org. Chem., 2005, 895 and references
cited therein.
8 Direct transmetalation with 2a may also occur.
9 The use of isolated A as the substrate gave product 3aa in 61% yield.
10 (a) M. Murakami and H. Igawa, Helv. Chim. Acta, 2002, 85, 4182; (b)
L. Navarre, S. Darses and J.-P. Genet, Chem. Commun., 2004, 1108; (c)
T. Miura, M. Shimada and M. Murakami, J. Am. Chem. Soc., 2005,
127, 1094; (d) L. Dong, Y.-J. Xu, L.-F. Cun, X. Cui, A.-Q. Mi,
Y.-Z. Jiang and L.-Z. Gong, Org. Lett., 2005, 7, 4285.
11 T. Mandai, S. Hasegawa, T. Fujimoto, M. Kawada, J. Nokami and
J. Tsuji, Synlett, 1990, 85.
12 For related reactions, see: (a) A. J. Chalk and S. A. Magennis, J. Org.
Chem., 1976, 41, 273; (b) S. Torii, H. Okumoto, F. Akahoshi and
T. Kotani, J. Am. Chem. Soc., 1989, 111, 8932; (c) A. Arcadi,
16 During the submission of our manuscript, Lautens and co-workers
reported the rhodium-catalysed desymmetrisation of a dicarbonate of
cis-cyclopent-4-ene-1,3-diol: F. Menard, T. M. Chapman,
C. Dockendorff and M. Lautens, Org. Lett., 2006, 8, 4569.
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