Chiral dihydrobenzofuran-based diphosphine (BICMAP): Optical resolution and application to rhodium(I)-catalyzed asymmetric 1,4-addition of aryl- and alkenylboronic acids to cyclic enones

Article abstract of DOI:10.1016/j.tetlet.2012.06.064

Chiral dihydrobenzofuran-based diphosphine ligand (BICMAP) 1 was used as a ligand for the rhodium(I)-catalyzed asymmetric 1,4-addition of arylboronic acids to cyclic enones up to 99% ee. We also found that the BICMAP-rhodium system was an efficient catalyst for the 1,4-addition of alkenylboronic acids to 2-cyclohexenone in good enantioselectivities.

Full text of DOI:10.1016/j.tetlet.2012.06.064

Tetrahedron Letters 53 (2012) 4562–4564
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Tetrahedron Letters
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Chiral dihydrobenzofuran-based diphosphine (BICMAP): optical resolution
and application to rhodium(I)-catalyzed asymmetric 1,4-addition of aryl- and
alkenylboronic acids to cyclic enones
⇑
Takashi Mino , Masatoshi Hashimoto, Katsunori Uehara, Yoshiaki Naruse, Shohei Kobayashi,
Masami Sakamoto, Tsutomu Fujita
Department of Applied Chemistry and Biotechnology, Graduate School of Engineering, Chiba University, 1-33, Yayoi-cho, Inage-ku, Chiba 263-8522, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Chiral dihydrobenzofuran-based diphosphine ligand (BICMAP) 1 was used as a ligand for the rhodium(I)-
catalyzed asymmetric 1,4-addition of arylboronic acids to cyclic enones up to 99% ee. We also found that
the BICMAP-rhodium system was an efficient catalyst for the 1,4-addition of alkenylboronic acids to 2-
cyclohexenone in good enantioselectivities.
Received 16 May 2012
Revised 7 June 2012
Accepted 13 June 2012
Available online 18 June 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Rhodium catalyst
Diphosphine
Asymmetric reaction
1
,4-Addition
The 1,4-addition to
a
,b-unsaturated carbonyl compounds is
The absolute configuration of (+)-2 was determined by X-ray
analysis of the (+)-2/(ꢀ)-DBTA complex. From an internal compar-
ison with (ꢀ)-DBTA, the absolute configuration of (+)-2 was de-
considered one of the most important C–C bond formations in or-
ganic synthesis. After the discovery of the BINAP-rhodium(I)-cata-
lyzed asymmetric 1,4-addition of aryl- and alkenylboronic acids by
Hayashi and Miyaura in 1998,1 many diphosphine ligands have
been used for the rhodium(I)-catalyzed asymmetric 1,4-addition
5
fined to be R (Fig. 2).
The X-ray structure of the (+)-2/(ꢀ)-DBTA complex also showed
that diphosphine oxide 2 and DBTA molecules were connected by
hydrogen bonds (Oꢁ ꢁ ꢁH = 1.701 Å). The resolved diphosphine oxi-
des (R)-(+)-2 and (S)-(ꢀ)-2 were converted into diphosphine (R)-
(+)-1 and (S)-(ꢀ)-1 using trichlorosilane-triethylamine. (R)-(+)-1
and (S)-(ꢀ)-1 were enantiomerically pure (>99% ee) according to
2
of boronic acids. On the other hand, we recently reported the syn-
thesis of an atropisomeric diphosphine ligand (BICMAP) 1 bearing
a dihydrobenzofuran (coumaran) core and its use in the palladium-
catalyzed Suzuki-Miyaura reaction and the Hartwig–Buchwald
3
6
amination. Here we report the rhodium-catalyzed asymmetric
the chiral phase HPLC after recrystallization.
1
,4-addition of aryl- and alkenylboronic acids to cyclic enones
We investigated the ability of chiral diphosphine 1 as a chiral li-
gand for the rhodium(I)-catalyzed asymmetric 1,4-addition of boro-
nic acids to cyclic enones. Phenylboronic acid and 2-cyclohexenone
were chosen as model substrates with 3 mol % of rhodium source
using (S)-BICMAP ((S)-1) as a chiral ligand (Fig. 1).
Although we previously reported that the optical resolution of
(
±)-1 was also carried out by HPLC with a chiral stationary phase
3
0
column, we herein tried optical resolution using O,O -dibenzoyl-
tartaric acid (DBTA) (Scheme 1). We added (ꢀ)-DBTA in EtOAc to
and 3.3 mol % of (S)-(ꢀ)-1 in dioxane/H
2
O for 5 h under an argon
as a rhodium
atmosphere at 100 °C (Table 1). Using [RhCl(C
2
4 2 2
H ) ]
2
h
the solution of (±)-2 in CHCl
3
at room temperature, filtered the
source with KOH as a base, we observed that the 1,4-addition pro-
formed solid, washed it with CHCl
3
, and dried it under vacuum
ceeded to give the corresponding product 3a in 91% yield with good
to give (+)-2/(ꢀ)-DBTA complex. This complex was converted into
the desired (+)-2 using a KOH solution. (ꢀ)-2 was also obtained by
a similar method using (+)-DBTA and enriched (ꢀ)-2 from the
4
mother liquor.
⇑
Corresponding author. Tel.: +81 43 290 3385; fax: +81 43 290 3401.
E-mail address: tmino@faculty.chiba-u.jp (T. Mino).
Figure 1. (S)-BICMAP ((S)-1).
0
040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.06.064

T. Mino et al. / Tetrahedron Letters 53 (2012) 4562–4564
4563
Scheme 1. Optical resolution of (±)-2 and preparation of (R)-(+)-1 and (S)-(ꢀ)-1.
Table 1
Rhodium(I)-catalyzed asymmetric 1,4-addition to cyclic enones using (S)-(ꢀ)-1
Entry
Rh source
[RhCl(C
[Rh(OH)(cod)]
n
R
Yielda (%)
Eeb (%)
1c
2
3
4
5
6
7
8
9
)
4 2
]
1
1
1
1
1
1
1
1
1
1
1
0
2
1
1
Ph
Ph
Ph
6 4
p-MeC H
m-MeC
o-MeC
3,5-DiMeC
p-MeOC
p-PhC
p-ClC
m-ClC
Ph
91 (3a)
92 (3a)
98 (3a)
80 (3b)
89 (3c)
50 (3d)
96 (3e)
64 (3f)
93 (3g)
31 (3h)
61 (3i)
96 (3j)
84 (3k)
78 (3l)
79 (3m)
96
95
99
97
99
89
99
96
98
98
98
94
95
89
93
2
H
2
2
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
Rh(acac)(C
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
2
H
4
4
4
4
4
4
4
4
4
4
4
4
4
)
)
)
)
)
)
)
)
)
)
)
)
)
2
2
2
2
2
2
2
2
2
2
2
2
2
6
H
H
4
4
6
6
H
3
6 4
H
6
H
4
H
6 4
H
4
10
11
12
13
14
15
6
Figure 2. The ORTEP drawing of (+)-2/(ꢀ)-DBTA complex (CCDC 878593).
Ph
trans-PhCH@CH
trans-n-C 13CH@CH
6
H
a
b
c
enantioselectivity (96% ee) (entry 1). When the reaction was carried
Isolated yields.
Determined by HPLC analysis using a chiral column.
.3 equiv of KOH was added.
7
out using [Rh(OH)(cod)]
2
as a rhodium source without adding KOH,
2
the enantioselectivity slightly decreased (95% ee) (entry 2). We
as a rhodium source1 and found that the
2 4 2
tested Rh(acac)(C H )
(
entries 14 and 15). The reactions gave corresponding products 3l
and 3m with 89% ee and 93% ee.
Finally, we tried the synthesis of flavanone. There have been
only a few reports for the synthesis of flavanone via rhodium(I)-
catalyzed asymmetric 1,4-addition of chromone, which has an
reaction proceeded with high enantioselectivity (99% ee) with good
yield (entry 3). Under optimized reaction conditions, we investi-
gated the asymmetric 1,4-addition of various arylboronic acids to
-cyclohexenone (entries 4–11).8 The reactions with 4-meth-
2
ylphenylboronic acid and 3-methylphenylboronic acid gave corre-
sponding products 3b and 3c in high enantioselectivities with
good yields (entries 4 and 5). Unfortunately, the reaction with 2-
methylphenylboronic acid led to moderate yield with 89% ee (entry
electron-donating group at the
c-position, with phenylboronic
9
acid. We applied the reaction of chromone with phenylboronic
acid using (S)-BICMAP as a chiral ligand (Scheme 2). The reaction
gave flavanone (3n) in 31% yield with 99% ee.
In summary, we described the optical resolution of BICMAP (1)
using DBTA and determined the absolute configuration. We found
6
). When we used 3,5-dimethylphenylboronic acid, the reaction
gave product 3e with high enantioselectivity (entry 7). On the other
hand, the reaction with 4-methoxyphenylboronic acid gave product
3
f in moderate yield with good enantioselectivity (entry 8). Using 4-
biphenylboronic acid led to good yield of product 3g in high enanti-
oselectivity (entry 9). When 4-chloro- and 3-chlorophenylboronic
acids were used, the reactions gave products 3h and 3i in low-to-
moderate yields with good enantioselectivities (entries 10 and
1
1). On the other hand, the reactions of 2-cyclopentenone and 2-
cycloheptenone with phenylboronic acid gave products 3j and 3k
with good enantioselectivities (entries 12 and 13). We also tested
the reaction of 2-cyclohexenone with various alkenylboronic acids
Scheme 2. Synthesis of flavanone (3n).

4
564
T. Mino et al. / Tetrahedron Letters 53 (2012) 4562–4564
(Daicel CHIRALPAKÒ IC, 0.46
u ꢃ 25 cm, UV 254 nm, Hexane:EtOH = 25:75,
that BICMAP-rhodium system was an efficient catalyst for the rho-
dium(I)-catalyzed asymmetric 1,4-addition of aryl- and alkenylbo-
ronic acids to cyclic enones including chromone up to 99% ee.
0
R R
.3 mL/min) t = 19.9 min (minor), t = 29.3 min (major).
(+)-2/(ꢀ)-DBTA complex: A white solid; mp 165–166 °C; 1H NMR (300 MHz,
5.
3
CDCl ) d 2.90–3.10 (m, 4H), 3.78 (dd, J = 9.2 and 18.4 Hz, 2H), 4.15 (dd, J = 8.7
and 16.6 Hz, 2H), 5.80 (s 2H), 6.64 (dd, J = 7.7 and 14.2 Hz, 2H), 6.96 (dd, J = 2.4
and 7.6 Hz, 2H), 7.10–7.65 (m, 28H), 8.03 (d, J = 7.3 Hz, 4H); 13C NMR (75 MHz,
Supplementary data
CDCl
J = 3.7 Hz), 124.1 (d, J = 16.9 Hz, Cx2), 126.7 (d, J = 13.4 Hz, Cx2), 127.6 (s, Cx2),
27.8 (d, J = 12.3 Hz, Cx4), 127.9 (d, J = 12.4 Hz, Cx4), 128.2 (s, Cx4), 129.0 (s,
3
) d 29.6 (s, Cx2), 70.6 (s, Cx2), 71.9 (s, Cx2), 120.9 (d, J = 1.8 Hz), 121.1 (d,
1
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.tetlet.2012.06.
Cx2), 129.4 (s, Cx2), 130.1 (s, Cx4), 131.3 (d, J = 2.5 Hz, Cx2), 131.3 (d, J = 2.6 Hz,
Cx2), 131.4 (d, J = 2.1 Hz, Cx2), 132.1 (d, J =10.2 Hz, Cx4), 132.3 (d, J =10.2 Hz,
0
64.
Cx4), 133.1 (s, Cx2), 133.5 (d, J = 8.6 Hz, Cx2), 158.8 (d, J = 15.5 Hz, Cx2), 165.2 (s,
Cx2), 167.1 (s, Cx2); 31P NMR (121 MHz, CDCl
) d 33.3; ½
aꢂ
20
3
D
3
+69.9 (c 0.5, CHCl )
Anal. Calcd for C58
.17; X-ray diffraction analysis data. Colorless prismatic crystals, monoclinic
space group P6(1) a = 13.1422(11) Å, b = 13.1422(11) Å, c = 53.315(4) Å,
H46Cl15
O
12
P
2
ꢁ5/6CHCl
3
: C, 64.45; H, 4.31. Found: C, 64.52; H,
References and notes
4
1
.
.
Takaya, Y.; Ogasawara, M.; Hayashi, T.; Sakai, M.; Miyaura, N. J. Am. Chem. Soc.
998, 120, 5579–5580.
(a) d’Herouville, F. L. B.; Millet, A.; Scalone, M.; Michelet, V. J. Org. Chem. 2011,
6, 6925–6930; (b) Berhal, F.; Wu, Z.; Genet, J.-P.; Ayad, T.; Ratovelmanana-
3
3
ꢀ1
V = 7974.7(12) Å , Z = 6,
c = 1.395 g/cm , l (MoKa) = 2.97 cm . The structure
1
was solved by the direct method of full-matrix least–squares, where the final R
and Rw were 0.0566 and 0.1376 for 45483 reflections.
Preparation of (R)-(+)-1: To a mixture of (R)-(+)-2 (383 mg, 0.60 mmol) and
triethylamine (3.0 mL, 21.6 mmol) in m-xylene (6 mL) was added trichlorosilane
2
7
6.
Vidal, V. J. Org. Chem. 2011, 76, 6320–6326; (c) Berhal, F.; Esseiva, O.; Martin, C.-
H.; Tone, H.; Genet, J.-P.; Ayad, T.; Ratovelomanana-Vidal, V. Org. Lett. 2011, 13,
(
1.82 mL, 18.0 mmol) at 0 °C under an Ar atmosphere. The reaction mixture was
2
2
806–2809; (d) Gök, Y.; Noël, T.; Van der Eycken, J. Tetrahedron: Asymmetry
010, 21, 2768–2774; (e) Korenaga, T.; Maenishi, R.; Hayashi, K.; Sakai, T. Adv.
stirred for 18 h at 110 °C. After being cooled to room temperature, the mixture
was quenched with 2 M NaOH aq (10 mL) and diluted with chloroform and
Synth. Catal. 2010, 352, 3247–3254; (f) Korenaga, T.; Osaki, K.; Maenishi, R.;
Sakai, T. Org. Lett. 2009, 11, 2325–2328; (g) Imamoto, T.; Saioh, Y.; Koide, A.;
Ogura, T.; Yoshida, K. Angew. Chem., Int. Ed. 2007, 46, 8636–8639; (h) Vandyck,
K.; Matthy, B.; Willen, M.; Robeyns, K.; Van Meervelt, L.; Van der Eycken, J. Org.
Lett. 2006, 8, 363–366; (i) Shimada, T.; Suda, M.; Nagano, T.; Kakiuchi, K. J. Org.
Chem. 2005, 70, 10178–10181; (j) Imamoto, T.; Sugita, K.; Yoshida, K. J. Am.
Chem. Soc. 2005, 127, 11934–11935; (k) Otomaru, Y.; Senda, T.; Hayashi, T. Org.
Lett. 2004, 6, 3357–3359.
water. The organic layer was dried over MgSO
pressure. The residue was purified by silica gel chromatography (elution with n-
hexane/ethyl acetate = 15/1) and recrystallization from n-hexane/ CHCl
4
, and concentrated under reduced
3
:
20
D
1
49 mg, 0.246 mmol, 41% as a white solid; mp 229–231 °C; >99% ee, ½aꢂ
1
+
3
2
58.3 (c 0.5, CHCl
3 3
); H NMR (CDCl ) d 2.91–3.02 (m, 2H), 3.08–3.20 (m, 2H),
.74 (dd, J = 8.9 and 18.7 Hz, 2H), 4.26–4.34 (m, 2H), 6.60 (dt, J = 1.6 and 7.5 Hz,
13
3
H), 7.08 (d, J = 7.5 Hz, 2H), 7.17–7.27 (m, 20H); C NMR (75 MHz, CDCl ) d 29.8
(
1
s, Cx2), 70.7 (s, Cx2), 124.0 (t, J = 21.7 Hz Cx4), 124.7 (s, Cx2), 126.7 (s, Cx2),
27.8 (d, J = 1.0 Hz Cx2), 127.9 (t, J = 3.6 Hz, Cx4), 128.0 (s, Cx2), 128.1 (t,
3
.
.
Mino, T.; Naruse, Y.; Kobayashi, S.; Oishi, S.; Sakamoto, M.; Fujita, T. Tetrahedron
Lett. 2009, 50, 2239–2241.
Resolution of (±)-2: To the solution of (±)-2 (0.375 g, 0.59 mmol) in CHCl
J = 3.0 Hz, Cx4), 133.3 (t, J = 10.3 Hz, Cx4), 134.0 (t, J = 10.5 Hz, Cx4), 137.3 (dd,
J = 3.5 and 4.5 Hz Cx2), 137.7 (dd, J = 5.4 and 6.6 Hz Cx2), 138.6 (dd, J = 6.2 and
3
4
3
(5 mL)
was added (ꢀ)-DBTA (0.211 g, 0.59 mmol) in EtOAc (5 mL) and stirred for 1 h at
room temperature. The mixture was diluted in CHCl (6 mL) and EtOAc (9 mL).
After 14 h at room temperature, the solid was filtered, washed with CHCl and
dried under vacuum to give (+)-2/(ꢀ)-DBTA complex. The solution of complex in
CHCl (5 mL) was added 2 M NaOH aq (2 mL) and stirred for 1 h at room
temperature. The organic layer was dried over MgSO , and concentrated under
reduced pressure to give (R)-(+)-2: 0.107 g, 0.17 mmol, 28% as a white solid; mp
31
7
.3 Hz, Cx2), 158.6 (t, J = 6.4 Hz, Cx2) P NMR (121 MHz, CDCl
3
) d ꢀ13.0; FD-MS
+
3
m/z (rel intensity) 606 (M , 100); HRMS (ESI-TOF-MS) m/z Calcd for
Ò
3
40 32 2 2
C H O P +H 607.1950. Found 607.1945; HPLC (Daicel CHIRALPAK IC,
0
.46
u
ꢃ 25 cm, UV 254 nm, Hexane:EtOH:MTBE = 89:1:10, 0.5 mL/min)
3
R
t = 8.5 min (R) (CD: kext (De) 254 (ꢀ)): Preparation of (S)-(ꢀ)-1: To a mixture
4
of (R)-(ꢀ)-2 (74.9 mg, 0.12 mmol) and triethylamine (0.6 mL, 4.2 mmol) in m-
xylene (1.6 mL) was added trichlorosilane (0.35 mL, 3.5 mmol) at 0 °C under an
Ar atmosphere. The reaction mixture was stirred for 6 h at 110 °C. After being
cooled to room temperature, the mixture was quenched with 6 M NaOH aq
2
0
1
1
3
56–158 °C; 96% ee, ½
aꢂ
D
3 3
+149 (c 0.5, CHCl ); H NMR (300 MHz, CDCl ) d 2.94–
.17 (m, 4H), 3.79 (dd, J = 8.6, 18.7 Hz, 2H), 4.18–4.26 (m, 2H), 6.76 (dd, J = 7.6
and 13.7 Hz, 2H), 7.03 (dd, J = 2.6 and 7.6 Hz, 2H), 7.24–7.30 (m, 4H), 7.33–7.49
(
3 mL) and diluted with chloroform and water. The organic layer was dried over
MgSO , and concentrated under reduced pressure. The residue was purified by
silica gel chromatography (elution with n-hexane/EtOAc = 10/1) and
recrystallization from n-hexane/CHCl : 27.5 mg, 45.3 mol, 39% as a white
1
3
(
m, 8H), 7.59–7.65 (m, 4H), 7.69–7.75 (m, 4H); C NMR (75 MHz, CDCl
3
) d 29.8
4
(
s, Cx2), 70.5 (s, Cx2), 121.5 (d, J = 3.6 Hz), 121.6 (d, J = 4.1 Hz), 123.8 (d,
J = 15.9 Hz Cx2), 126.5 (d, J = 12.6 Hz Cx2), 127.8 (d, J = 12.0 Hz Cx8), 130.2 (d,
J = 105.9 Hz Cx2), 130.3 (d, J = 1.8 Hz Cx2), 130.9 (d, J = 2.6 Hz Cx4), 132.2 (d,
J = 9.5 Hz Cx4), 132.3 (d, J = 10.0 Hz Cx4), 134.4 (d, J = 105.3 Hz Cx2), 134.9 (d,
3
l
20
D
1
solid; mp 229–231 °C; >99% ee, ½
a
ꢂ
ꢀ63.3 (c 0.5, CHCl
3
); H NMR (CDCl
.91–3.02 (m, 2H), 3.08–3.20 (m, 2H), 3.74 (dd, J = 8.8 and 18.7 Hz, 2H), 4.26–
.34 (m, 2H), 6.60 (dt, J = 1.7 and 7.5 Hz, 2H), 7.08 (d, J = 7.5 Hz, 2H), 7.16–7.30
3
) d
2
4
3
1
J = 104.1 Hz, Cx2), 158.7 (d, J = 15.1 Hz Cx2), P NMR (121 MHz, CDCl
3
) d 29.9;
+
EI-MS m/z (rel intensity) 638 (M , 23); HRMS (ESI-TOF-MS) m/z Calcd for
13
(
3
m, 20H); C NMR (75 MHz, CDCl ) d 29.8 (s, Cx2), 70.7 (s, Cx2), 124.0 (t,
Ò
C
40
H
32
O
4
P
2
+H 639.1849. Found 639.1826; HPLC (Daicel CHIRALPAK IC,
ꢃ 25 cm, Hexane:EtOH = 25:75, 0.3 mL/min, UV 254 nm) t = 19.9 min
= 29.6 min (minor). The combined filtrates were concentrated in
(5 mL) was added 2 M KOH aq (2 mL)
and stirred for 1 h at room temperature. The organic layer was dried over
MgSO , and concentrated under reduced pressure. To the solution of solid
0.241 g, 0.38 mmol) in CHCl (5 mL) was added (+)-DBTA (0.135 g, 0.38 mmol)
in EtOAc (5 mL) and stirred for 1 h at room temperature. The mixture was
diluted in CHCl (6 mL) and EtOAc (9 mL). After 14 h at room temperature, the
solid was filtered, washed with CHCl
and dried under vacuum to give (ꢀ)-2/(+)-
DBTA complex. The solution of complex in CHCl (5 mL) was added 2 M KOH aq
2 mL) and stirred for 1 h at room temperature. The organic layer was dried over
J = 21.6 Hz Cx4), 124.7 (s, Cx2), 126.7 (s, Cx2), 127.8 (d, J = 1.4 Hz Cx2), 127.9 (t,
J = 3.6 Hz, Cx4), 128.0 (s, Cx2), 128.1 (t, J = 3.0 Hz, Cx4), 133.3 (t, J = 10.4 Hz, Cx4),
0
.46
u
R
(
major), t
R
1
6
34.0 (t, J = 10.4 Hz, Cx4), 137.3 (dd, J = 3.5 and 4.5 Hz Cx2), 137.7 (dd, J = 5.5 and
.6 Hz Cx2), 138.6 (dd, J = 6.2 and 7.5 Hz, Cx2), 158.6 (t, J = 6.5 Hz, Cx2) P NMR
vacuum. The solution of residue in CHCl
3
31
+
(
121 MHz, CDCl
3
) d ꢀ13.0; EI-MS m/z (rel intensity) 606 (M , 6); HRMS (ESI-
4
TOF-MS) m/z Calcd for C40
CHIRALPAK IA, 0.46
32 2 2
H O P
+H 607.1950. Found 607.1954; HPLC (Daicel
ꢃ 25 cm, UV 254 nm, Hexane:EtOH = 97:3, 0.3 mL/min)
= 23.6 min (S) (CD: kext ) 254 (+)).
(
3
Ò
u
t
R
(De
3
7
8
.
.
Duan, W.-L.; Iwamura, H.; Hayashi, T. J. Am. Chem. Soc. 2007, 129, 2130–2138.
General procedure for the rhodium(I)-catalyzed asymmetric 1,4-addition to cyclic
enones using (S)-(ꢀ)-1: To a mixture of aryl- or alkenylboronic acid (2.0 mmol),
3
3
(
Rh(acac)(C
dioxane (1.0 mL) and H
2 4 2
H ) (3.09 mg, 12.0 lmol), and (S)-(ꢀ)-1 (8.08 mg, 13.3 lmol) in a
MgSO
4
, and concentrated under reduced pressure to give (S)-(ꢀ)-2: 0.102 g,
2
O (0.1 mL) was added cyclic enone (0.40 mmol) at room
20
D
0
.16 mmol, 27% as a white solid; mp 156–158 °C; 96% ee, ½
aꢂ
ꢀ154 (c 0.5,
temperature under an Ar atmosphere. The reaction mixture was stirred for 5 h
at 100 °C. After being cooled to room temperature, the mixture was quenched
1
3 3
CHCl ); H NMR (300 MHz, CDCl ) d 2.94–3.16 (m, 4H), 3.78 (dd, J = 8.6, 18.7 Hz,
2
H), 4.18–4.26 (m, 2H), 6.76 (dd, J = 7.6 and 13.7 Hz, 2H), 7.03 (dd, J = 2.6 and
with sat. NaHCO
water and brine, and dried over Na
rotary evaporator and the residue was purified by column chromatography
elution with n-hexane/EtOAc = 15-6/1).
3
aq and diluted with EtOAc. The organic layer was washed with
7
(
.6 Hz, 2H), 7.24–7.30 (m, 4H), 7.33–7.46 (m, 8H), 7.59–7.65 (m, 4H), 7.69–7.75
2
SO . The filtrate was concentrated with a
4
m, 4H); 13C NMR (75 MHz, CDCl
3
) d 29.8 (s, Cx2), 70.5 (s, Cx2), 121.6 (d,
J = 3.6 Hz), 121.7 (d, J = 4.3 Hz), 123.8 (d, J = 15.9 Hz Cx2), 126.5 (d, J = 12.7 Hz
Cx2), 127.8 (d, J = 11.7 Hz Cx8), 130.2 (d, J = 104.9 Hz Cx2), 130.3 (d, J = 2.4 Hz
Cx2), 130.9 (d, J = 2.8 Hz Cx4), 132.2 (d, J = 9.8 Hz Cx4), 132.3 (d, J = 10.0 Hz Cx4),
(
9.
(a) Han, F.; Chen, G.; Zhang, X.; Liao, J. Eur. J. Org. Chem. 2011, 2928–2931; (b)
Korenaga, T.; Hayashi, K.; Akaki, Y.; Maenishi, R.; Sakai, T. Org. Lett. 2011, 13,
1
34.5 (d, J = 103.1 Hz Cx2), 134.9 (d, J = 104.4 Hz, Cx2), 158.7 (d, J = 15.2 Hz Cx2),
2022–2025; (c) Chen, J.; Chen, J.; Lang, F.; Zhang, X.; Cun, L.; Zhu, J.; Deng, J.;
31
+
P NMR (121 MHz, CDCl
3
) d 30.0; EI-MS m/z (rel intensity) 638 (M , 22); HRMS
+H 639.1849. Found 639.1835; HPLC
Liao, J. J. Am. Chem. Soc. 2010, 132, 4552–4553.
(
ESI-TOF-MS) m/z Calcd for C40H O P
32 4 2