Asymmetric aza-Claisen rearrangement of allyl imidates catalyzed by homochiral cationic palladium(II) complexes

Article abstract of DOI:10.1016/S0957-4166(98)00059-7

The asymmetric aza-Claisen rearrangement of (E)-3-alkyl-2-propenyl N- [4-trifluoromethyl)phenyl]benzimidates was catalyzed by a homochiral cationic palladium(II) complex generated from PdCl₂{(S)-2-(2- diphenylphosphino)phenyl-4-benzyloxazoline}

Full text of DOI:10.1016/S0957-4166(98)00059-7

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 9 (1998) 1065–1072
Asymmetric aza-Claisen rearrangement of allyl imidates
catalyzed by homochiral cationic palladium(II) complexes
Yasuhiro Uozumi«,a Kazuhiko Kato b and Tamio Hayashi« b,∗
aFaculty of Pharmaceutical Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8603, Japan
bDepartment of Chemistry, Faculty of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Received 4 February 1998; accepted 6 February 1998
Abstract
The asymmetric aza-Claisen rearrangementof (E)-3-alkyl-2-propenylN-[4-trifluoromethyl)phenyl]benzimidates
was catalyzed by homochiral cationic palladium(II) complex generated from PdCl2{(S)-2-(2-
a
diphenylphosphino)phenyl-4-benzyloxazoline} and silver tetrafluoroborate (Pd:silver=1:1) to give (S)-N-(1-
alkyl-2-propenyl)-N-[4-(trifluoromethyl)phenyl]benzamide of up to 81% ee. © 1998 Published by Elsevier
Science Ltd. All rights reserved.
1. Introduction
Transition metal catalyzed [3,3]-sigmatropic rearrangements are among the important transformations
in modern synthetic organic chemistry.1,2 However, only scattered attention has been paid to catalytic
asymmetric [3,3]-sigmatropic rearrangements which would constitute a powerful strategy for the synthe-
sis of a variety of optically active compounds. The aza-Claisen rearrangement of allyl imidates catalyzed
by divalent palladium species is a typical case.3 Recently, Overman reported the first example of a
catalytic asymmetric rearrangement of allyl imidate 1a, where a cationic palladium(II) complex bearing
an optically active tertiary diamine as a ligand catalyzed the rearrangement to give N-allyl amide 2a in
up to 60% ee.4
On the other hand, we have reported the palladium-catalyzed asymmetric Heck reaction5 and the
Wacker-type reaction6 where a cationic palladium(II) species plays a key role in the activation of the
carbon–carbon double bond as well as in the enantioface selection.7,8 As a part of our efforts to develop
a wide utility of the cationic chiral palladium(II) catalysts, the asymmetric aza-Claisen rearrangement
of allyl imidates was examined. We describe herein that higher enantioselectivity (up to 81% ee) was
obtained by use of a cationic palladium(II) catalyst of 2-(2-diphenylphosphino)phenyl-4-alkyloxazoline
∗
Corresponding author. E-mail: thayashi@th1.orgchem.kuchem.kyoto-u.ac.jp
0957-4166/98/$19.00 © 1998 Published by Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(98)00059-7

1066
Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
(phox, 4) in the asymmetric aza-Claisen rearrangement of 3-alkyl-2-propenyl N-arylbenzimidates 1 to
N-(1-alkyl-2-propenyl)-N-arylbenzamide 2 of up to 81% ee (Scheme 1).
Scheme 1.
2. Results and discussion
Rearrangement of (E)-2-hexenyl N-[4-(trifluoromethyl)phenyl]benzimidate 1a to N-(1-hexen-3-yl)-
N-[4-(trifluoromethyl)phenyl]benzamide 2a was examined in the presence of palladium(II) catalysts
coordinated with chiral bis(oxazoline), phosphino-oxazoline, and bis(phosphine) ligands under sev-
eral reaction conditions (Scheme 1). The N-allyl amide 2a was isolated by chromatography on silica
gel and the enantiomeric excess was determined by HPLC analysis using a chiral stationary column
(Chiralpack AD; eluent: hexane:isopropanol=9:1). The absolute configuration was determined by com-
parison of the specific rotation with that reported for optically active 2a.4 The results summarized
in Table 1 reveal that the most stereoselective ligand is (S)-(+)-2-(2-(diphenylphosphino)phenyl)-4-
(benzyl)oxazoline ((S)-bn-phox 4a)9 (entry 1). According to the procedures reported by Overman,4
a cationic palladium catalyst was generated from dichloro[(S)-(+)-2-(2-(diphenylphosphino)phenyl)-
4-(benzyl)oxazolyl]palladium(II) [PdCl2{(S)-bn-phox}] by treatment with 1 equiv. (to Pd) of silver
tetrafluoroborate.10 The rearrangement of 1a proceeded in refluxing 1,2-dichloroethane to give 81% yield
25
of N-allyl amide (S)-2a of 70% ee ([α]D +50.5 (c 0.23, dichloromethane), lit.4 for (R)-2a of 55% ee:
25
[α]D −37.2 (c 0.5, dichloromethane)). The reaction carried out at 40°C raised the enantiomeric excess
to 76% ee, though the reaction is slower (entry 2). Dicationic palladium(II) catalyst generated by addition
of 2 equiv. (to Pd) of silver tetrafluoroborate is not effective for the rearrangement to 2a, resulting in
carbon–oxygen bond cleavage to give N-[4-(trifluoromethyl)phenyl]benzamide (3) (entry 3). The effects
of the added silver salts on the reaction pathway are consistent with those reported by Overman.4 Without
silver salt, PdCl2{(S)-bn-phox)} did not catalyse the rearrangement at all. The reaction with other
phosphino-oxazoline ligands, which have isopropyl 4b9 and t-butyl 4c9 substituents at the C4-position,
proceeded with 36% and 50% enantioselectivity, respectively (entries 5 and 6). Ferrocene analog 511
exhibited moderate catalytic activity and stereoselectivity (entry 7). Chiral bis(oxazoline) ligands,12 2,2-
bis(oxazolyl)propane 6,13 2,20-bioxazolyl 714 and 2,20-bis[4-(benzyl)oxazolyl]-1,10 -binaphthyl ((S,S)-
bn-boxax) 815 gave 2a with much lower enantioselectivity (entries 8, 9 and 10). The palladium complex
of (S)-BINAP 916 was found to be stereoselective, but less catalytically active (entry 11).

Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
1067
Table 1
Asymmetric rearrangement of 1 catalyzed by cationic palladium(II) complexesa
The rearrangement of (Z) isomer 1a0 gave an enantiomeric product (R)-2a though the selectivity was
lower than that observed for (E) isomer 1a (entry 12). Allyl imidate 1b which has a phenyl substituent

1068
Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
at the imidate nitrogen instead of 4-trifluoromethylphenyl gave N-allyl benzamide 2b in high yield with
moderate enantiomeric purity (entry 13). The highest stereoselectivity was observed in the reaction of
1c, which gave 2c in 81% ee under the same reaction conditions (entry 14).
In conclusion, it was found that a cationic palladium(II) complex generated from PdCl2{(S)-bn-phox}
and silver tetrafluoroborate was an efficient catalyst for asymmetric aza-Claisen rearrangement of allyl
imidates giving N-allyl amide derivatives of high % ee.
3. Experimental
3.1. General
Optical rotations were measured with a JASCO DIP-370 polarimeter. 1H NMR spectra were measured
with a JEOL JNM-LA500 (500 MHz) spectrometer in CDCl3 with tetramethylsilane as an internal
standard. Chemical shifts are reported in δ ppm. HPLC analyses were performed on a Shimadzu LC-9A
liquid chromatograph system with chiral stationary phase column, Daicel Chemical Co. Ltd, Chiralpack
AD.
3.2. Materials
Optically active ligands, (S)-bn-phox 4a,9 (S)-ip-phox 4b,9 (S)-tb-phox 4c,9 (S)-(−)-2-[(S)-2-
(diphenylphosphino)ferrocenyl]-4-(isopropyl)oxazoline 5,11 2,2-bis(oxazolyl)propane 6,13 2,20-
bioxazolyl 7,14 and 2,20-bis[4-(benzyl)oxazolyl]-1,10 -binaphthyl ((S,S)-bn-boxax) 815 were prepared
according to the reported procedures. Optically active palladium(II) complex PdCl2{(S)–BINAP} was
prepared according to the reported procedure.5e,17 THF, benzene and hexane were distilled from sodium
benzophenone ketyl under nitrogen. Dichloromethane and dichloroethane were distilled from calcium
hydride under nitrogen.
3.3. Preparation of PdCl2(phosphine-oxazoline) complexes
A typical procedure is given for the preparation of dichloro[(S)-2-(2-(diphenylphosphino)phenyl)-4-
(benzyl)oxazoline]palladium(II) (PdCl2{(S)-bn-phox}):
3.3.1. Dichloro[(S)-2-(2-(diphenylphosphino)phenyl)-4-(benzyl)oxazoline]palladium(II) (PdCl2{(S)-
bn-phox})
A solution of 250 mg (0.59 mmol) of (S)-(+)-2-(2-(diphenylphosphino)phenyl)-4-(benzyl)oxazoline
((S)-bn-phox 4a) in 5 mL of benzene was added to a mixture of 154 mg (0.59 mmol) of PdCl2(CH3CN)2
and 5 mL of benzene. The reaction mixture was stirred for 20 min. A yellow precipitate was col-
lected by filtration and washed with benzene to give 352 mg (98% yield) of dichloro[(S)-(+)-2-(2-
20
(diphenylphosphino)phenyl)-4-(benzyl)oxazoline]palladium(II): mp 247°C (dec); [α]D +497 (c 0.27,

Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
1069
1
chloroform); H NMR δ 1.68 (br t, J=12.7 Hz, 1H), 3.87 (dd, J=13.3, 3.5 Hz, 1H), 4.30 (dd, J=8.8, 4.9
Hz, 1H), 4.39 (br t, J=9.3 Hz, 1H), 5.80 (m, 1H), 6.99 (m, 1H), 7.21 (m, 5H), 7.45 (m, 4H), 7.58 (m, 5H),
7.74 (m, 3H), 8.10 (m, 1H); 13C NMR δ 40.64, 67.98, 72.39, 162.09; 31P NMR δ 26.70. Anal. calcd for
C28H24NOPCl2Pd: C, 56.16; H, 4.01; N, 2.34. Found: C, 56.39; H, 3.89; N, 2.15.
3.3.2. Dichloro[(S)-2-(2-(diphenylphosphino)phenyl)-4-(isopropyl)oxazoline]palladium(II) (PdCl2{(S)-
ip-phox})
20
1
89% Yield: mp 239°C (dec); [α]D +704 (c 0.08, chloroform); H NMR δ 0.02 (d, J=6.9 Hz, 3H),
0.82 (d, J=7.4 Hz, 3H), 2.68 (m, 1H), 4.38 (dd, J=9.3, 5.4 Hz, 1H), 4.50 (br t, J=9.3 Hz, 1H), 5.61 (m,
1H), 6.82 (m, 1H), 7.36–7.60 (m, 9H), 7.71 (m, 3H), 8.14 (m, 1H); 13C NMR δ 12.80, 18.57, 30.47,
68.99, 71.30, 161.40; 31P NMR δ 21.01. Anal. calcd for C24H24NOPCl2Pd: C, 52.34; H, 4.39; N, 2.54.
Found: C, 52.05; H, 4.33; N, 2.53.
3.3.3. Dichloro[(S)-2-(2-(diphenylphosphino)phenyl)-4-(t-butyl)oxazoline]palladium(II) (PdCl2{(S)-tb-
phox})
20
1
78% Yield: mp 263°C (dec); [α]D +464 (c 0.18, chloroform); H NMR δ 1.56 (s, 9H), 4.54 (m,
2H), 5.53 (dd, J=7.9, 5.6 Hz, 1H), 6.93 (m, 1H), 7.40 (m, 4H), 7.49–7.64 (m, 7H), 7.72 (br t, 1H),
8.19 (m, 1H); 13C NMR δ 25.86, 29.71, 34.39, 70.72, 74.58, 162.49; 31P NMR δ 25.42. Anal. calcd for
C25H26NOPCl2Pd: C, 46.90; H, 4.09; N, 2.19. Found: C, 46.71; H, 4.01; N, 2.25.
3.3.4. Dichloro{(S)-2-[(S)-2-(diphenylphosphino)ferrocenyl]-4-(isopropyl)oxazoline}palladium(II)
20
1
84% Yield: mp 265°C (dec); [α]D −958 (c 0.04, chloroform); H NMR δ 1.01 (d, J=6.9 Hz, 3H),
1.07 (d, J=6.9 Hz, 3H), 3.10 (m, 1H), 3.81 (s, 5H), 4.38 (br t, J=9.3 Hz, 1H), 4.49 (dd, J=8.8, 4.4
Hz, 1H), 4.53 (m, 1H), 4.77 (br s, 1H), 5.10 (br s, 1H), 5.33 (m, 1H), 7.26–7.41 (m, 5H), 7.64 (m,
3H), 8.33 (m, 2H); 13C NMR δ 14.91, 18.77, 29.98, 73.14, 167.55; 31P NMR δ 15.73. Anal. calcd for
C28H28NOPCl2PdFe: C, 51.06; H, 4.29; N, 2.13. Found: C, 51.17; H, 4.37; N, 1.99.
3.4. Preparation of imidates 1
A typical procedure is given for the preparation of (E)-2-hexenyl N-[4-(trifluoromethyl)phenyl]benz-
imidate 1a.8
3.4.1. (E)-2-Hexenyl N-[4-(trifluoromethyl)phenyl]benzimidate 1a
To a mixture of 649 mg (4.03 mmol) of 4-trifluoromethylaniline and 608 mg (6.02 mmol) of
triethylamine in 20 mL of dichloromethane was added 620 mg (4.41 mmol) of benzoyl chloride at 0°C
and the reaction mixture was stirred for 30 min. The reaction mixture was washed with 10% hydrochloric
acid. The organic layer was dried over sodium sulfate and concentrated under reduced pressure to give
1
crude N-[4-(trifluoromethyl)phenyl]benzamide (1.04 g, 97% yield): H NMR δ 7.52 (br t, J=7.9 Hz,
2H), 7.59 (br t, J=7.4 Hz, 1H), 7.64 (d, J=8.4 Hz, 2H), 7.79 (d, J=8.4 Hz, 2H), 7.88 (br d, J=8.3 Hz, 2H),
7.93 (br s, 1H).
A mixture of 596 mg (2.25 mmol) of N-[4-(trifluoromethyl)phenyl]benzamide and 469 mg
(2.25 mmol) of phosphorus pentachloride was heated at 85°C for 1 h. After being cooled to
room temperature, volatile materials were removed under reduced pressure to give crude N-[4-
1
(trifluoromethyl)phenyl]benzimidoyl chloride (630 mg, 99% yield): H NMR δ 7.07 (br d, J=8.35 Hz,
2H), 7.50 (br t, J=7.9 Hz, 2H), 7.58 (br t, J=7.4 Hz, 1H), 7.67 (d, J=8.4 Hz, 2H), 8.17 (br d, J=7.8 Hz,
2H).

1070
Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
To a suspension of 121 mg (2.20 mmol) of sodium hydride in 35 mL of THF was added a solution of
220 mg (2.20 mmol) of (E)-2-hexen-1-ol in THF (5 mL) at 0°C and the mixture was stirred for 10 min.
To the mixture was added 610 mg (2.15 mmol) of N-[4-(trifluoromethyl)phenyl]benzimidoyl chloride
at 0°C. The reaction mixture was stirred at room temperature for 4 h and a small amount of water was
added. The entire solution was extracted with chloroform. The organic layer was dried over sodium
sulfate, concentrated, and chromatographed on silica gel (eluent: EtOAc:hexane=1:19) to give 634 mg
(83% yield) of (E)-2-hexenyl N-[4-(trifluoromethyl)phenyl]benzimidate (1a): 1H NMR δ 0.92 (t, J=7.4
Hz, 3H), 1.45 (br sextet, J=7.4 Hz, 2H), 2.09 (br q, J=6.9 Hz, 2H), 4.81 (d, J=6.9 Hz, 2H), 5.75–5.91
(m, 2H), 6.78 (d, J=8.3 Hz, 2H), 7.22–7.34 (m, 5H), 7.42 (d, J=8.3 Hz, 2H).
3.4.2. (Z)-2-Hexenyl N-[4-(trifluoromethyl)phenyl]benzimidate 1a0
61% Yield; 1H NMR δ 0.93 (t, J=7.3 Hz, 3H), 1.44 (br sextet, J=7.3 Hz, 2H), 2.17 (br q, J=7.3 Hz,
2H), 4.92 (d, J=6.4 Hz, 2H), 5.71 (m, 1H), 5.76 (m, 1H), 6.79 (d, J=8.3 Hz, 2H), 7.28 (m, 5H), 7.42 (d,
J=8.3 Hz, 2H); 13C NMR δ 13.69, 22.64, 29.73, 62.91, 121.70, 124.11, 124.49 (q, J=30 Hz), 124.52 (q,
J=272 Hz), 126.10 (br t, J=5 Hz), 128.09, 129.26, 130.22, 130.78, 134.82, 151.78, 159.13. Anal. calcd
for C20H20NOF3: C, 69.15; H, 5.80; N, 4.03. Found: C, 69.22; H, 6.07; N, 4.05.
3.4.3. (E)-2-Hexenyl N-(phenyl)benzimidate 1b
77% Yield; 1H NMR δ 0.94 (t, J=7.4 Hz, 3H), 1.45 (br sextet, J=7.4, 2H), 2.08 (br q, J=6.9 Hz, 2H),
4.81 (d, J=5.9 Hz, 2H), 5.77 (m, 1H), 5.88 (m, 1H), 6.71 (br d, J=7.4 Hz, 2H), 6.94 (br t, J=7.3 Hz, 1H),
7.15–7.32 (m, 7H).
3.4.4. (E)-4-Methyl-2-pentenyl N-[4-(trifluoromethyl)phenyl]benzimidate 1c
86% Yield; 1H NMR δ 0.95 (d, J=6.9 Hz, 6H), 2.27 (br octet, 1H), 4.72 (d, J=5.9 Hz, 2H), 5.63 (dt,
J=15.2, 5.9 Hz, 1H), 5.76 (dd, J=15.2, 6.4 Hz, 1H), 6.69 (d, J=8.3 Hz, 2H), 7.13 (m, 2H), 7.22 (m, 3H),
7.32 (d, J=8.3 Hz, 2H); 13C NMR δ 22.12, 30.90, 67.80, 121.39, 121.68, 124.48 (q, J=32 Hz), 124.83
(q, J=270 Hz), 126.08 (q, J=4 Hz), 128.09, 129.26, 130.20, 130.88, 142.86, 151.81, 159.05. Anal. calcd
for C20H20NOF3: C, 69.15; H, 5.80; N, 4.03. Found: C, 69.05; H, 6.07; N, 3.76.
3.5. Asymmetric aza-Claisen rearrangement of imidates 1 with catalysts prepared from PdCl2{(S)-bn-
phox}
A typical procedure is given for the asymmetric rearrangement of 1a (Table 1, entry 1). To a
suspension of 2.0 mg (10 µmol) of AgBF4 in 0.1 mL of dichloromethane was added a solution of 6.6
mg (11 µmol) of dichloro[(S)-(+)-2-(2-(diphenylphosphino)phenyl)-4-(benzyl)oxazolyl]palladium(II)
[PdCl2{(S)-bn-phox}] in 0.1 mL of dichloromethane at room temperature. After 5 min, precipitated
silver chloride was removed by filtration. The filtrate was concentrated in vacuo to give an orange solid.
The orange solid was dissolved in 0.2 mL of 1,2-dichloroethane and 34.7 mg (0.10 mmol) of (E)-2-
hexenyl-N-[4-(trifluoromethyl)phenyl]benzimidate 1a in 0.1 mL of 1,2-dichloroethane was added. The
reaction mixture was stirred at 40°C for 24 h. After being cooled to room temperature, removal of solvent
followed by preparative TLC on silica gel (hexane:EtOAc=19:1) gave 14.2 mg (41%) of N-(1-hexen-3-
yl)-N-[4-(trifluoromethyl)phenyl]benzamide 2a, (41% yield, 76% ee): [α]D20 +51.3 (c 0.18, chloroform).
1H NMR δ 0.94 (t, J=7.4 Hz, 3H), 1.43 (br sextet, J=7.4 Hz, 2H), 1.57–1.65 (m, 1H), 1.68–1.76 (m, 1H),
5.22 (d, J=10.3 Hz, 1H), 5.23 (m, 1H), 5.29 (d, J=17.6 Hz, 1H), 5.89 (ddd, J=17.6, 10.3, 7.4 Hz, 1H),
7.14 (br d, J=8.8 Hz, 2H), 7.17 (br d, J=7.8 Hz, 2H), 7.24 (m, 3H), 7.14 (br d, J=8.4 Hz, 2H). The
enantiomeric purity of 2a was determined by HPLC analysis with a chiral stationary phase column.

Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
1071
Conditions: column, Daicel Chemical Industries Ltd, Chiralpack AD; eluent: hexane:isopropanol=9:1;
detection 254 nm light. The absolute configuration was determined to be (S) by measurement of the
specific rotation: [α]D +50.5 (c 0.23, dichloromethane), lit.8 for (R)-2a of 55% ee: [α]D −37.2 (c
25
25
0.5, dichloromethane).
3.5.1. (S)-(+)-N-(1-Hexen-3-yl)-N-phenylbenzamide 2b
88% Yield, 47% ee: [α]D20 +28.4 (c 0.15, chloroform); 1H NMR δ 0.94 (t, J=7.4 Hz, 3H), 1.45 (sextet,
J=7.4 Hz, 2H), 2.08 (q, J=6.9 Hz, 2H), 4.81 (d, J=5.9 Hz, 2H), 5.77 (m, 1H), 5.85 (m, 1H), 6.71 (br d,
J=7.4 Hz, 2H), 6.94 (br t, J=7.3 Hz, 1H), 7.15–7.32 (m, 7H).
3.5.2. (S)-(+)-N-(4-Methyl-1-penten-3-yl)-N-(4-trifluoromethyl)phenyl]benzamide 2c
20
1
30% Yield, 81% ee: [α]D +71.9 (c 0.10, chloroform); H NMR δ 0.94 (d, J=6.9 Hz, 3H), 1.19 (d,
J=6.9 Hz, 3H), 2.30 (m, 1H), 4.48 (br t, J=9.8 Hz, 1H), 5.21 (d, J=9.8 Hz, 1H), 5.22 (d, J=17.2 Hz, 1H),
5.91 (br t, J=9.8 Hz, 1H), 7.14 (d, J=8.3, 2H), 7.15–7.26 (m, 5H), 7.45 (d, J=8.3 Hz, 2H); 13C NMR δ
20.24, 20.37, 29.81, 70.36, 119.09, 123.71 (q, J=274 Hz), 125.91 (br s), 127.90, 128.39 (q, J =34 Hz),
128.71, 129.43, 129.66, 135.96, 136.48, 146.11, 170.55. Anal. calcd for C20H20NOF3: C, 69.15; H, 5.80;
N, 4.03. Found: C, 69.08; H, 5.84; N, 3.97.
Acknowledgements
This work was supported by the ‘Research for the Future’ Program, the Japan Society for the
Promotion of Science and a Grant-in-Aid for Scientific Research, the Ministry of Education, Japan. Y.
U. thanks the Shorai Foundation for Science and Technology for partial financial support of this work.
References
1. For reviews, see: (a) Rhoads, S. J.; Raulins, N. R. Org. React. 1975, 22. (b) Overman, L. E. Acc. Chem. Res. 1980, 13, 218.
(c) Winterfeldt, E. Foryschr. Chem. Forsch. 1971, 16, 75. (d) Ziegler, F. E. Acc. Chem. Res. 1977, 10, 227.
2. For recent examples, see: (a) Mizutani, M.; Sanemitsu, Y.; Tamaru, Y.; Yoshida, Z. J. Org. Chem. 1983, 48, 4583. (b) van
der Baan, J. L.; Bickelhaupt, F. Tetrahedron Lett. 1986, 27, 6267. (c) Ohshima, M.; Murakami, M.; Mukaiyama, T. Chem.
Lett. 1984, 1535. (d) Sugiura, M.; Nakai, T. Terahedron Lett. 1996, 37, 7991. (e) Hayashi, T.; Yamamoto, A.; Ito, Y. Synth.
Commun. 1989, 19, 2109. (f) Lutz, R. P. Chem. Rev. 1984, 84, 205. (g) Trebellas, J. C.; Olechowski, J. R.; Jonassen, H.
B. J. Organomet. Chem. 1966, 6, 412. (h) Heimbach, P.; Molin, M. J. Organomet. Chem. 1973, 49, 477. (i) Heimbach, P.;
Molin, M. J. Organomet. Chem. 1973, 49, 483. (j) Overman, L. E.; Jacobsen, E. J. J. Am. Chem. Soc. 1982, 104, 7225.
3. (a) Overman, L. E. Angew. Chem., Int. Ed. Engl. 1984, 23, 579. (b) Schenck, T. G.; Bosnich, B. J. Am. Chem. Soc. 1985,
107, 2058. (c) Ikariya, T.; Ishikawa, Y.; Hirai, K.; Yoshikawa, S. Chem. Lett. 1982, 1815. (d) Metz, P.; Mues, C.; Schoop,
A. Tetrahedron 1992, 48, 1071. (e) Gonda, J.; Helland, A.-C.; Ernst, B.; Bellus, D. Synthesis 1993, 729. (f) Mehmandoust,
M.; Petit, Y.; Larchevêque, M. Tetrahedron Lett. 1992, 33, 4313.
4. Calter, M.; Hollis, T. K.; Overman, L. E.; Ziller, J.; Zipp, G. G. J. Org. Chem. 1997, 62, 1449.
5. (a) Ozawa, F.; Kubo, A.; Hayashi, T. J. Am. Chem. Soc. 1991, 113, 1417. (b) Ozawa, F.; Kubo, A.; Hayashi, T. Tetrahedron
Lett. 1992, 33, 1485. (c) Ozawa, F.; Hayashi, T. J. Organomet. Chem. 1992, 428, 267. (d) Ozawa, F.; Kobatake, Y.; Hayashi,
T. Tetrahedron Lett. 1993, 34, 2505. (e) Ozawa, F.; Kubo, A.; Matsumoto, Y.; Hayashi, T.; Nishioka, E.; Yanagi, K.;
Moriguchi, K.-I. Organometallics 1993, 12, 4188.
6. (a) Uozumi, Y.; Kato, K.; Hayashi, T. J. Am. Chem. Soc. 1997, 119, 5063. (b) Uozumi, Y.; Kato, K.; Hayashi, T., submitted.
7. Shibasaki and Overman independently reported an asymmetric Heck reaction, where cationic chiral palladium(II) brought
about high catalytic activity as well as enantioselectivity, see: (a) Sato, Y.; Sodeoka, M.; Shibasaki, M. J. Org. Chem. 1989,
54, 4738. (b) Carpenter, N. E.; Kucera, D. J.; Overman, L. E. J. Org. Chem. 1989, 54, 5846.

1072
Y. Uozumi et al. / Tetrahedron: Asymmetry 9 (1998) 1065–1072
8. Recent examples of catalytic asymmetric reactions by use of cationic chiral palladium complexes, see: (a) Sodeoka, M.;
Ohrai, K.; Shibasaki, M. J. Org. Chem. 1995, 60, 2648. (b) Sugiura, M.; Nakai, T. Angew. Chem., Int. Ed. Engl. 1997, 36,
2366.
9. (a) Dawson, G. J.; Frost, C. G.; Williams, J. M. J.; Coote, S. J. Tetrahedron Lett. 1993, 34, 3149. (b) Sprinz, J.; Helmchen,
G. Tetrahedron Lett. 1993, 34, 1769. (c) von Matt, P.; Pfaltz, A. Angew. Chem., Int. Ed. Engl. 1993, 32, 566.
10. The effect of various silver salts, AgOTf, AgSbF6, AgPF6, and AgOCOCF3, was examined. Similar asymmetric induction
and catalytic activity were observed for all salts except AgOCOCF3 (little catalytic activity under the same reaction
conditions).
11. (a) Sammakia, T.; Latham, H. A.; Schaad, D. R. J. Org. Chem. 1995, 60, 10. (b) Richards, C. J.; Damalidis, T.; Hibbs, D.
E.; Hursthouse, M. B. Synlett 1995, 74. (c) Nishibayashi, Y.; Uemura, S. Synlett 1995, 79.
12. For recent reviews, see: (a) Togni, A.; Venanzi, L. M. Angew. Chem., Int. Ed. Engl. 1994, 33, 497. (b) Pfaltz, A. Acc. Chem.
Res. 1993, 26, 339.
13. Evans, D. A.; Woerpel, K. A.; Hinman, M. M.; Faul, M. M. J. Am. Chem. Soc. 1991, 113, 726.
14. Müller, D.; Umbricht, G.; Weber, B.; Pfaltz, A. Helv. Chim. Acta 1991, 74, 232.
15. Uozumi, Y.; Kyota, H.; Kishi, E.; Kitayama, K.; Hayashi, T. Tetrahedron: Asymmetry 1996, 7, 1603.
16. Takaya, H.; Mashima, K.; Koyano, K.; Yagi, M.; Kumobayashi, H.; Taketomi, T.; Akutagawa, S.; Noyori, R. J. Org. Chem.
1986, 51, 629.
17. Matsumoto, Y.; Hayashi, T.; Ito, Y. Tetrahedron 1994, 50, 335.