Kinetic resolutions by enantioselective Pauson-Khand-type reaction

Article abstract of DOI:10.1002/adsc.200800657

A kinetic resolution of 1-arylallyl propargyl ethers by enantioselective Pauson-Khand-type reaction catalysts was successfully carried out. While cationic rhodium(I) with a BINAP-based ligand having an electron-deficient phosphine is the choice for the sl

Full text of DOI:10.1002/adsc.200800657

COMMUNICATIONS
DOI: 10.1002/adsc.200800657
Kinetic Resolutions by Enantioselective Pauson–Khand-Type
Reaction
Dong Eun Kim,a Jaesung Kwak,a In Su Kim,a and Nakcheol Jeonga,*
a
Department of Chemistry, Korea University, Seoul 136-701, Korea
Fax : (+82) 2-3290-3121; phone: (+82) 2-3290-3136; e-mail: njeong@korea.ac.kr
Received: October 27, 2008; Published online: January 12, 2009
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.200800657.
Abstract: A kinetic resolution of 1-arylallyl prop-
argyl ethers by enantioselective Pauson–Khand-
type reaction catalysts was successfully carried out.
While cationic rhodium(I) with a BINAP-based
ligand having an electron-deficient phosphine is the
choice for the slow reacting substrates, neutral iri-
dium(I) with a BINAP-based ligand possessing an
electron-rich phosphine provided excellent results
for the more reactive substrates.
tion time (conditions b in Table 1). Better and more
reliable results were obtained by employing the newly
developed reaction conditions utilizing a Rh(I) cata-
lyst at ambient temperature.[5c] The reaction of race-
mic 1a-1 at ambient temperature under a reduced
pressure of CO (0.1 atm) afforded an efficient kinetic
resolution (conditions c in Table 1).[5]
The following characteristics of the reaction are
worth mentioning. First, it was easy to determine the
termination point of the reaction. Once the reaction
reached 50% conversion, its progress became noticea-
bly slower. Second, the reaction provided the PKR
product 2a-1 as a single diastereomer.[6] The absolute
configuration of 2a-1 was [R(C1), R(C2)] as shown in
Keywords: allyl propargyl ethers; atropisomerism;
iridium; kinetic resolution; Pauson–Khand reaction;
rhodium
Table 1. Preliminary experiments of the kinetic resolution
through asymmetric Pauson–Khand type reaction.
Kinetic resolution has been established as a useful
tool for the preparation of an optically active com-
pound from a racemic mixture. Enzymatic kinetic res-
olution has a long history, but transition metal-medi-
ated kinetic resolution has become popular over the
last two decades due to the progress made in the de-
velopment of chiral catalysts for asymmetric reac-
tions.[1] In this communication, we would like to
report the first kinetic resolution by a catalytic asym-
metric Pauson–Khand-type reaction.[2]
The study was initiated with the racemic substrate
1-arylallyl propargyl ether, 1a-1. Either Rh(I) or Ir(I)
catalysts under thermal conditions originally devel-
oped by us[3] and Shibata,[4] respectively, were tested.
The results were confusing and indicated that this re-
action might require much effort for optimization.
For example, under the conditions employing Rh(I)
(conditions a in Table 1), the reaction was too fast for
its halfway point to be judged precisely. Thus the data
initially obtained were inconsistent. On the other
hand, the Ir(I)-catalyzed reaction was too slow for
practical use, resulting in an unsatisfactory chemical
yield of the PKR product even after a prolonged reac-
Conditions[a] t [h] 1a-1
Yield [%]/ee
2a-1
Yield [%]/ee
[%]
3a-1
Yield
[%]
[%]
a
b
c
0.5 48/60
12 70/27
1.5 56/40
50/82
20/92
33/85
–
–
10
[a]
Condtions a: [Rh(CO)2Cl]2 (3 mol%), (R)-BINAP (9
mol%), AgOTf (12 mol%) in THF at 808C under CO (1
atm); conditions b: [IrACHTNUTRGNE(NUG COD)2Cl]2 (15 mol%), (R)-4-tol-
BINAP (30 mol%), toluene, CO (1 atm), reflux; condi-
tions c: [Rh(CO)2Cl]2 (3 mol%), (R)-BINAP (9 mol%),
AgOTf (12 mol%), Ar:CO (10:1, 1 atm), THF, 18–208C.
Adv. Synth. Catal. 2009, 351, 97 – 102
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
97

Dong Eun Kim et al.
COMMUNICATIONS
Table 2. Ligand effects on the kinetic resolution of (Æ) 1a-1.
Entry[a]
Lig.
d (31P, ppm)[c]
Dihedral angle (o)[d]
1a-1[f]
2a-1[g]
3a-1
Yield [%]/ee [%]
Yield [%]/ee [%]
Yield [%]
1
2
3
(R)-L1
(R)-L2
(R)-L3
(R)-L4
(R)-L5
(R)-L6
(S)-L7
(S)-L8
À16.9
À15.8
À14.4
À13.8
À13.7
À13.6
À14.3
À12.3
78.3
42/40
48/37
56/40
50/71
58/50
62/27
40/56[h]
43/99[h]
25/59
23/67
32/85
40/91
36/89
31/58
23/66i
45/83[i]
20
20
10
5
–
5
[e]
78.3
4[b]
5[b]
6
78.0
[e]
[e]
7
8
73.0
72.2
25
<2
[a]
[Rh(CO)2Cl]2 (3 mol%), L* (6 mol%), AgOTf (9 mol%), Ar:CO (10:1, 1 atm), THF, 18–208C.
Reactions at 408C.
[b]
[c]
[d]
[e]
[f]
We correlated the electron density on phosphorus through the 31P NMR spectra of the free ligands.[5a]
Structures minimized by Molecular Mechanics calculations (CAChe MM2 program).[5]
This number has not been calculated, but is assumed to be similar to that of L3.
The absolute configuration of ent-1 was (S).
[g]
[h]
[i]
The absolute configuration at C-1 and C-2 of ent-2 was (R,R).
The absolute configuration of 1a-1 is (R).
The absolute configuration at C-1 and C-2 of 2a-1 is (S,S).
Table 1, when (R)-BINAP was employed as a chiral in terms of the chemical yield and enantioselectivity.
ligand.[7] Third, compound 3, a rearranged product of The reaction proceeded smoothly at ambient temper-
1, was obtained sporadically because of the intrinsic ature and thus a significantly improved combined
Lewis acidity of the catalyst.[8] Fourth, the efficiency chemical yield of the PKR product 2a and the re-
of the reaction and its stereoselectivity depended sen- maining 1a was obtained. Although this rate accelera-
sitively not only on the electronic and steric charac- tion provided the isomer 3 noticeably in several cases
ters of the ligands, but also on the electron density of (1a-3 and 1a-4 in Table 3), where the electron density
the alkyne.[9] The ligand effects are summarized in of the alkyne was rich, the combined chemical yield
Table 2. From Table 2, we learned that (S)-Difluor- in most cases was normally excellent. Furthermore,
phos (L8) and (R)-4-trifluorotolyl-BINAP (L4) are excellent enantioselectivities were obtained especially
the best choices of ligand.[9]
In an earlier study, we were able to summarize the selectivities of PKR product need to be improved.
ligand effects on this reaction.[9] Ligands possessing
Meanwhile, the reaction by the catalyst possessing
for the remaining starting materials, but the enantio-
the more electron-rich phosphorus atom accelerated L4, which has a relatively wider dihedral angle in the
the reaction. In addition, for ligands having similar metal complex together with the electron-deficient
electron density to that of phosphorus, those ligands phosphorus, was slowed down substantially and thus
having a narrower dihedral angle in the metal-bound required slight warming (408C) for the reliable initia-
Rh(I) complex accelerated the reaction substantially. tion of the reaction.
However, this acceleration is often tainted by side re-
However, this condition provided excellent ees (>
actions, resulting in a decrease of the chemical yield. 90%) for the PKR products with chemical yields uni-
In this light, ligand L8, whose dihedral angle in the formly greater than 40%. The only exceptions were
metal-bound ligand is smaller than those of BINAP those substrates having an electron-deficient alkyne,
derivatives and for which phosphorus is significantly which gave a relatively inferior result (80% ee).
deshielded (12.3 ppm), provides a good compromise
98
asc.wiley-vch.de
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2009, 351, 97 – 102

Kinetic Resolutions by Enantioselective Pauson–Khand-Type Reaction
COMMUNICATIONS
Table 3. Kinetic resolution of 1a and 1b by cationic chiral Rh(I) catalysts.
Substrates
R1
Reaction by a catalyst with (S)-L8
Reaction by a catalyst with (R)-L4
ent-1[a]
ent-2[b]
3
ent-1[c]
ent-2[d]
3
R2
t
Yield [%]/
Yield [%]/ Yield S[1d,10]
t
Yield [%]/
Yield [%]/
Yield S[1d,10]
[h] ee [%]
ee [%]
[%]
[h] ee [%]
ee [%]
[%]
O Ph (1a) C6H5 (1)
1.7 44/99
1.5 38/99
45/80
61/65
<2
0
41
17
1.2 48/84
1.0 48/90
41/90
49/90
<5
–
83
69
2-
(CH3O)C6H4
(2)
4-
1.5 40/99
45/76
10
24
1.0 58/53
40/94
–
–
66
(CH3O)C6H4
(3)
4-CH3C6H4
(4)
(3,5-
1.2 40/91
2.0 42/95
49/75
51/70
8
12
19
1.0 52/83
0.8 48/76
44/92
40/83
65
33
<5
<5
diCH3)C6H3
(5)
4-ClC6H4 (6) 3.0 40/96
4-CF3C6H4 (7) 4.0 42/90
2-ClC6H4 (8) 2.5 46/73
59/63
55/75
54/60
42/80
–
–
–
–
17
13
9
1.0 52/60
1.0 48/71
3.0 52/61
1.0 56/77
46/85
46/80
44/82
33/90
–
–
–
–
29
25
23
36
Naphth 4-
1.0 50/90
58
(1b)
(CH3O)C6H4
(1)
C6H5 (2)
4-CF3C6H4 (3) 1.0 50/84
1.0 54/84
40/92
48/80
–
–
200
30
1.0 57/56
1.0 56/65
38/91
41/80
–
–
44
17
[a]
[b]
[c]
[d]
The absolute configuration of ent-1 was (R).
The absolute configuration at C-1 and C-2 of ent-2 was (S,S).
The absolute configuration of ent-1 was (S).
The absolute configuration at C-1 and C-2 of ent-2 was (R,R).
The bigger naphthyl group was introduced in place ble mixture of diastereoemers and regioisomers of di-
of phenyl (substrate 1a-1 vs. 1b-2) to exaggerate the meric product[12] (entry 1 in Table 4). Product 4c-1
steric factor at the pre-existing stereogenic centre C- was presumably derived from the intermediate 8 in
2. This modification gave rise to a considerable im- Scheme 1.[13] Since the binding of the remaining (Æ)-
provement in the optical purity of the PKR product 1c-1 to 6’ to form 8 was non-stereoselective and the
(from 80% to 92% ee) when a catalyst bearing L8 energy difference between the two competing transi-
was used (1b-2 in Table 3). However, under the condi- ent intermediates 6 and 6’ seemed not to be signifi-
tions in which a catalyst bearing L4 was used, its in- cant, the optical purity of the PKR product was at a
fluence on the enantioselectivity was marginal and its negligible level (10–20% ee).
effect on the chemical yield was slightly negative,
since the steric congestion near the reaction site made suppression of 4c-1 and the improvement of enantio-
the reaction less efficient. selectivity of 2c-1. However, all attempts employing
Extensive optimization efforts have focused on the
The replacement of the aryl substituent on the Rh(I) catalysts for optimization so far were unsuc-
alkyne with an alkyl substituent made a dramatic cessful (entries 2 and 3 in Table 4).
change of the reaction course. It is mainly attributed
Differing from the reactions with the slow reacting
to the fact that the presence of an alkyl group on the substrates such as 1a and 1b (conditions b in Table 1),
alkyne expedited the PKR reaction substantially as the reactions of these intrinsically reactive substrates
well as side reactions, resulting in a kind of parallel like 1c proceeded nicely with the much less reactive
kinetic resolution.[11]
Ir(I)-based catalyst (3 mol%).[4] Although it required
The characteristics of this case are summarized as significantly more forcing conditions (reflux in tolu-
follows. The reaction of 1c-1 under the previously de- ene, 12 hr) than the reaction with cationic Rh(I),
scribed conditions went on too fast to stop at the half- much cleaner results, affording only the remaining
way point of completion. Instead, the reaction con- starting material 1c-1 in 54% yield and 67% ee and
sumed 1c-1 completely in less than an hour even at PKR product 2c-1 in 36% with 96% ee after 12 h with
ambient temperature and provided the desired PKR (R)-L3 (entry 6 in Table 4). The absolute stereochem-
product 2c-1 together with a significant amount of a istry of product is consistent with the previous study
new product 4c-1, which was present as an insepara- on Rh(I) catalyst; that is, (+)-[R(C1),R(C2)]-2c-1 and
Adv. Synth. Catal. 2009, 351, 97 – 102
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
99

Dong Eun Kim et al.
COMMUNICATIONS
Table 4. Kinetic resolution of (Æ)-1c having alkyl substituents on the alkyne.
Entry
R2
C[a]
Lig.
t [h]
ent-1c[b]
Yield [%]/ee [%]
ent-2c[c]
Yield [%]/ee [%]
4c+11c
Yield[f] [%]
1
2
3
4
5
6
7
8
Me
(1c-1)
a
b
c
(R)-L3
(R)-L3
(R)-L3
(R)-L1
(R)-L2
(R)-L3
(R)-L3
(R)-L4
(R)-L5
(R)-L6
(S)-L7
(S)-L8
(R)-L3
(R)-L4
1
1
1
0
0
0
35/8
50
55
45
10
10
–
<5
10[g]
8
–
–
10
–
–
25/11
44/14
36/90
32/91
36/96
41/92
40/82
40/82
20/97
12/88[e]
20/92[e]
40/90
42/81
12
12
12
24
12
12
12
12
12
28
24
52/60
55/63
54/67
46/78
42/91
48/76
80/26
88/8[d]
74/33[d]
53/75
49/94
d
d
9
10
11
12
13
14
Allyl ACHTUNGTRENNUNG(1c-2)
[a]
Conditions a: [Rh(CO)2Cl]2 (3 mol%), (R)-BINAP (9 mol%), AgOTf (12 mol%), Ar:CO (10:1, 1 atm), THF, 18–208C;
conditions b: same as conditions a, but slow addition of 1c-1 in THF into a solution of the catalyst to maintain the high
dilution; conditions c: [Rh(CO)2Cl]2 (3 mol%), (R)-BINAP (9 mol%), AgOTf (12 mol%), CO (1 atm), THF, 18–208C;
conditions d: [IrACHTUNGTRENNUNG(COD)2Cl]2 (3 mol%), ligand (9 mol%), toluene, CO (1 atm), reflux.
[b]
[c]
[d]
[e]
[f]
The absolute configuration of ent-1c was (R).
The absolute configuration at C-1 and C-2 of ent-2c was (S,S).
The absolute configuration of ent-1c was (S).
The absolute configuration at C-1 and C-2 of ent-2c was (R,R).
4c is obtained.
[g]
4c is contaminated by 11c.
Scheme 1. Competing pathways in the enantioslective PKR.
100
asc.wiley-vch.de
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2009, 351, 97 – 102

Kinetic Resolutions by Enantioselective Pauson–Khand-Type Reaction
COMMUNICATIONS
1H), 4.81 (d, J=16.1 Hz, 1H), 5.23 (d, J=16.1 Hz, 1H),
7.37–7.58 (m, 10H); 13C NMR (100 MHz, CDCl3): d=40.1,
50.9, 67.4, 84.7, 126.3, 128.4, 128.7, 128.95, 128.98, 129.0,
130.7, 135.5, 139.2, 177.6, 206.6; HR-MS (FAB+): m/z=
299.1045 [M+Na]+, calcd. for C19H16O2Na: 299.1048; [a]2D1:
+30.3 (c 7.0, CH2Cl2); the ee value was determined as 80%
by HPLC analysis using a chiral column (DAICEL CHIR-
ALPAK AS-H, n-hexane/i-PrOH=9/1, flow 1.5 mLminÀ1,
detection at 254 nm): retention time: 11.92 min (major) and
14.11 min (minor).
(À)-(S)-1c-1 were obtained when (R)-BINAP was em-
ployed.[7]
The ligand effect on the chemical yields and stereo-
selectivies was also evident, but less explicable than
the reaction of the Rh(I) catalyst. The catalysts
having (R)-BINAP (L3) gave rise to a better enantio-
selectivity for the PKR product, up to 92% ee in 41%
yield after optimization with 24 h reaction time
(entry 7 in Table 4) and the catalyst having (R)-L4
yielded a better optical purity for the remaining 1c-1,
affording up to 91% ee in 42% yield, albeit the forma-
tion of 4c-1 was more considerable in the latter case
(entries 7 and 8 in Table 4).
The substrate scope of this condition was examined
with 1c-2 by employing catalysts having (R)-L3 and
(R)-L4. The recovered (+)-1c-2 was obtained in 75%
ee and 53% yield and PKR product 2c-2 in 90% ee
and 41% yield by utilizing an Ir(I)-based catalyst
bearing (R)-L3, respectively (entry 13 in Table 4).
In conclusion, we have developed a highly efficient
kinetic resolution of (Æ)-1-arylallyl propargyl ethers
(1) by an enantioselective Pauson–Khand-type reac-
tion. The choice of catalyst depended on the sub-
strates: a cationic Rh(I) catalyst for the substrates
having aryl substituents on the alkyne and a neutral
Ir(I) catalyst for the substrates having alkyl substitu-
ents. In addition, the optical purity of the recovered
allyl propargyl ether 1 or PKR product 2 was found
to be sensitive to the ligands employed and was fully
optimized.
(+)-(R)-4-[3-(1-phenyl-allyloxy)-prop-1-ynyl]benzene (1a-
1): IR (KBr): n=2230 cmÀ1 1H NMR (300 MHz, CDCl3):
;
d=4.35 (d, J=15.7 Hz, 1H), 4.43 (d, J=15.7 Hz, 1H), 5.13
(d, J=6.9 Hz, 1H), 5.30 (d, J=10.1 Hz, 1H), 5.37 (d, J=
17.3 Hz, 1H), 6.00 (ddd, J=17.3, 10.1, 6.9 Hz, 1H), 7.30–
7.49 (m, 10H); 13C NMR (75 MHz, CDCl3): d=56.4, 81.6,
85.5, 86.5, 117.5, 123.0, 127.4, 128.1, 128.5, 128.7, 128.8,
132.0, 138.3, 140.4; HR-MS (EI+): m/z=248.1218 [M+],
calcd. for C18H16O: 248.1201; [a]21: +63.4 (c 4.8, CH2Cl2);
the ee value was determined asD 99% by HPLC analysis
using a chiral column (DAICEL CHIRALPAK OB-H, n-
hexane/i-PrOH=30/1, flow 0.7 mLminÀ1, detection at
254 nm): retention time: 16.42 min (major).
4-[3-(3-Phenylallyloxy)-prop-1-ynyl]benzene (3a-1): This
product was obtained as an inseparable mixture of E- and
Z-isomers (3:1). IR (KBr): n=2233 cmÀ1
;
1H NMR
(300 MHz, CDCl3, for E-isomer ): d=4.33 (d, J=6.0 Hz,
2H), 4.45 (s, 2H), 6.35 (dt, J=16.0, 6.0 Hz, 1H), 6.69 (d, J=
16.0 Hz, 2H), 7.24–7.58 (m, 10H); 1H NMR (300 MHz,
CDCl3, for Z-isomer ): d=4.23 (d, J=6.0 Hz, 2H), 4.45 (s,
2H), 6.35 (dt, J=15.6, 6.0 Hz, 1H), 6.66 (d, J=15.6 Hz,
1H), 7.24–7.58 (m, 10H); 13C NMR (100 MHz, CDCl3, mix-
ture of E- and Z-isomers): d=58.2, 70.6, 71.0, 85.3, 86.6,
122.9, 125.5, 126.2, 126.76, 126.80, 128.0, 128.1, 128.6, 128.7,
128.8, 132.0, 132.8, 133.6, 136.8; HR-MS (EI+): m/z=
248.1202 [M+], calcd. for C18H16O: 248.1201.
Experimental Section
General Procedure for Kinetic Resolution by
Cationic Rh(I) under Reduced Pressure of CO
General Procedure for Kinetic Resolution by Neutral
Ir(I) under Atmospheric Pressure of CO
[Rh(CO)2Cl]2 (2.4 mg, 0.006 mmol, 3 mol%) and a ligand
(12.4 mg for (S)-L8, 0.012 mmol, 6 mol%) were placed in
THF (1 mL) and the mixture was stirred for 0.5 hour at
208C under an atmospheric pressure of argon. A solution of
AgOTf (5.2 mg, 0.020 mmol, 10 mol%) in THF (1 mL) was
added, and the resultant reaction mixture was stirred for an-
other 0.5 hour at 208C. The argon atmosphere was replaced
with a mixture of CO in argon (1: 10, 1 atm), and then a so-
lution of 1a-1 (50 mg, 0.201 mmol) in THF (1 mL) was intro-
duced. The reaction mixture was stirred at 208C. The prog-
ress of the reaction was monitored by TLC and/or by
HPLC. At the half-way point to completion, the reaction
was stopped by removal of gas. The crude reaction mixture
was concentrated under vacuum, and then the residue was
purified by column chromatography on silica gel using an n-
hexane/ethyl acetate mixture as an eluent to afford (+)-
(S,S)-2a-1; yield: 25.0 mg (0.090 mmol, 45%) as well as (+)-
(R)-1a-1; yield:22.2 mg (0.089 mmol, 44%), respectively.
(+)-(S,S)-3,6-Diphenyl-3a,4-dihydro-1H,3H-cyclopen-
[IrACTHNGUTERN(UNG COD)Cl]2 (5.5 mg, 0.008 mmol, 3 mol%) and a ligand
(12.0 mg for (R)-L3) were placed in toluene (1.5 mL) and
the mixture was stirred for 0.5 hour at 408C under an atmos-
pheric pressure of CO.
A solution of 1c-1 (50 mg,
0.269 mmol) in toluene (1.5 mL) was introduced. The reac-
tion mixture was stirred at reflux. The progress of the reac-
tion was monitored by TLC and/or by HPLC. At the half-
way point to completion, the reaction was stopped by re-
moval of the gas. The crude reaction mixture was concen-
trated under vacuum, and then the residue was purified by
column chromatography on silica gel using an n-hexane/
ethyl acetate mixture as an eluent to afford(+)-(R,R)-2c-1;
yield: 23.6 mg (0.110 mmol, 41%) and (À)-(S)-1c-1; yield:
23.1 mg (0.124 mmol, 46%).
(+)-(R,R)-6-Methyl-3-phenyl-3a,4-dihydro-1H-cyclopen-
ta[c]furan-5(3H)-one (2c-1): IR (KBr): n=1709 cmÀ1
;
1H NMR (300 MHz, CDCl3): d=1.80 (s, 3H), 2.26 (dd, J=
17.8, 2.8 Hz, 1H), 2.63 (dd, J=17.8, 6.3 Hz, 1H), 3.09 (m,
1H), 4.36 (d, J=10.4 Hz, 1H), 4.69 (d, J=15.4 Hz, 1H),
4.87 (d, J=15.4 Hz, 1H), 7.31–7.40 (m, 5H); 13C NMR
(75 MHz, CDCl3): d=9.1, 38.5, 50.9, 65.9, 85.1, 126.2, 128.6,
128.9, 133.4, 139.6, 176.4, 208.7; HR-MS (EI+): m/z=
ta[c]furan-5-one (2a-1): IR (KBr): n=1710 cmÀ1 1H NMR
;
(400 MHz, CDCl3): d=2.50 (dd, J=18.0, 3.1 Hz, 1H), 2.81
(dd, J=18.0, 6.3 Hz, 1H), 3.27 (m, 1H), 4.43 (d, J=10.2 Hz,
Adv. Synth. Catal. 2009, 351, 97 – 102
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
101

Dong Eun Kim et al.
COMMUNICATIONS
214.0988, [M+], calcd. for C14H14O2: 214.0994; found; [a]2D5:
+33.7 (c 7.6, CH2Cl2); the ee value was determined as 92%
by HPLC analysis using a chiral column (DAICEL CHIR-
ALPAK OD-H, n-hexane/i-PrOH=9/1, flow 1.0 mLminÀ1,
detection at 254 nm): retention time: 14.35 min (major) and
16.34 min (minor).
1135; d) N. Jeong, in: Modern Rhodium-Catalyzed Or-
ganic Reactions, (Ed.: P. A. Evans), Wiley-VCH, Wein-
heim, 2005, pp 215–240.
[4] T. Shibata, K. Takagi, J. Am. Chem. Soc. 2000, 122,
9852–9853.
[5] a) T. Kobayashi, Y. Koga, K. Narasaka, J. Organomet.
Chem. 2001, 624, 73–87; b) T. M. Schmid, G. Consiglio,
Chem. Commun. 2004, 2318–2319; c) D. E. Kim, I. S.
Kim, V. Ratovelomanana-Vidal, J.-P. GenÞt, N. Jeong,
J. Org. Chem. 2008, 73, 7985–7989.
[6] H. Wang, J. R. Sawyer, P. A. Evans, M.-H. Baik,
Angew. Chem. 2008, 120, 348–351; Angew. Chem. Int.
Ed. 2008, 47, 342–345.
[7] The determination of the relative stereochemistry of
2a-1 and 2c-1 as well as the absolute stereochemistry is
described in the Supporting Information. In fact, we
determined the absolute stereochemistry of the remain-
ing 1a-1 and 1c-1 by comparing of the optical purity of
the remaining 1a-1 and 1c-1 with the corresponding en-
antiomers whose absolute stereochemistry is well estab-
lished.
(À)-(S)-[1-(But-2-ynyloxy)allyl]benzene
(1c-1):
IR
1
(KBr):=2227 cmÀ1; H NMR (300 MHz, CDCl3): d=1.87 (t,
J=2.2 Hz, 3H), 4.06 (dq, J=15.2, 2.2 Hz, 1H), 4.13 (dq, J=
15.2, 2.5 Hz, 1H), 4.99 (d, J=6.6 Hz, 1H), 5.24 (d, J=
10.2 Hz, 1H), 5.30 (d, J=17.1 Hz, 1H), 5.96 (ddd, J=17.1,
10.2, 6.6 Hz, 1H), 7.27–7.37 (m, 5H); 13C NMR (75 MHz,
CDCl3): d=3.9, 56.2, 75.4, 81.4, 82.6, 117.2, 127.3, 128.0,
128.7, 138.4, 140.5; HR-MS (EI+): m/z=186.1061 [M+],
calcd. for C13H14O: 186.1045; [a]25: À31.6 (c 5.0, CH2Cl2);
The ee value was determined asD 78% by HPLC analysis
using a chiral column (DAICEL CHIRALPAK OJ-H, n-
hexane/i-PrOH=30/1, flow 1.0 mLminÀ1, detection at
254 nm): retention time: 11.77 min (major) and 19.06
(minor).
[8] Compound 3 was obtained as a mixture of the geomet-
rical isomers.
Acknowledgements
[9] The electronic and steric characteristics of the ligands
mentioned in this manuscript and their effects on the
reaction rate and enantioselectivity are described in the
literature; a) D. E. Kim, C. Choi, I. S. Kim, S. Jeulin, V.
Ratovelomanana-Vidal, J.-P. GenÞt, N. Jeong, Synthesis
2006, 23, 4053–4059; b) D. E. Kim, C. Choi, I. S. Kim,
S. Jeulin, V. Ratovelomanana Vidal, J.-P. GenÞt, N.
Jeong, Adv. Synth. Catal. 2007, 349, 1999–2006.
[10] The S value, unless the yield of 3 is negligible, should
be counted as an approximate measure. It was calculat-
ed based on the assumption that 3, if it was formed,
was formed from both enantiomers of 1 equally. How-
ever, this may not be the case and, since the possibility
of a parallel kinetic resolution cannot be eliminated,
these numbers are only intended as a rough estimation
in these cases. The S value with emphasis on the recov-
ered substrate was calculated using the equation
This work was supported by the Korea Science and Engineer-
ing Foundation (KOSEF) Grant (No. R01–2007–000–10534–
0) and by the Korea Research Foundation Grant (KRF-2007–
313-C00414) funded by the Korean Govemment (MOST and
MOEHRD), respectively.
References
[1] a) H. B. Kagan, J. C. Fiaud, in: Topics in Stereochemis-
try, (Eds.: E. L. Eliel, J. C. Fiaud), Wiley, New York,
1988, Vol. 18, pp 249–330; b) A. H. Hoveyda, M. T.
Didiuk, Curr. Org. Chem. 1998, 2, 537–574; c) G. R.
Cook, Curr. Org. Chem. 2000, 4, 869–885; d) H. B.
Kagan, Tetrahedron 2001, 57, 2449–2459; e) J. M.
Keith, J. F. Larrow, E. N. Jacobsen, Adv. Synth. Catal.
2001, 343, 5–26; f) K. Faber, Chem. Eur. J. 2001, 7,
5005–5010; g) J. R. Dehli, V. Gotor, Chem. Soc. Rev.
2002, 31, 365–370; h) D. E. Robinson, S. D. Bull, Tetra-
hedron: Asymmetry 2003, 14, 1407–1446; i) E. Vedejs,
M. Jure, Angew. Chem. 2005, 117, 4040–4069; Angew.
Chem. Int. Ed. 2005, 44, 3974–4001.
[(1Àc)
emphasis on product was calculated using the equation
ln (1+ee)]/ln
A
R
ACHTUNGTNER(NUNG 1+ee)] while the S value with
A
E
N
ACHTUNGTRENNUNG
[11] a) H. Pellissier, Tetrahedron 2003, 59, 8291–8327;
b) F. F. Huerta, A. B. E. Minidis, J.-E. Bꢁckvall, Chem.
Soc. Rev. 2001, 30, 321–331.
[12] LC-MS analysis exhibited that this inseparable mixture
consisted of seven isomers having the same molecular
weight corresponding to the dimeric product of 1c-1
(MW: 372.2).
[13] a) P. A. Evans, K. W. Lai, J. R. Sawyer, J. Am. Chem.
Soc. 2005, 127, 12466–12467; b) P. A. Evans, J. R.
Sawyer, K. W. Lai, J. C. Huffman, Chem. Commun.
2005, 3971–3973.
[2] N. Jeong, in: Comprehensive Organometallic Chemistry
III, Vol. 11, (Eds.: R. H. Crabtree, M. P. Mingos),
Elsevier, Oxford, 2006, pp 335–366.
[3] a) N. Jeong, B. K. Sung, Y. K. Choi, J. Am. Chem. Soc.
2000, 122, 6771–6772; b) N. Jeong, B. K. Sung, J. S.
Kim, S. B. Park, S. D. Seo, J. Y. Shin, K. Y. In, Y. K.
Choi, Pure Appl. Chem. 2002, 74, 85–91; c) N. Jeong,
D. H. Kim, J. H. Choi, Chem. Commun. 2004, 1134–
102
asc.wiley-vch.de
ꢀ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2009, 351, 97 – 102