Importance of planar chirality in chiral catalysts with three chiral elements: The role of planar chirality in 2′-substituted 1,1′-P,N-ferrocene ligands on the enantioselectivity in Pd-catalyzed allylic substitution

Article abstract of DOI:10.1021/ja002657q

A series of novel planar chiral 2′subtituted 1,1′-P,N-ferrocene ligands 9-11, 14, and 16 were prepared with diastereopurity >99:1 and found to be effective in asymmetric allylic alkylation and amination reactions, Ligand 14 furnished the highest enantiomeric excess, 98.5% and 96.5% ee in alkylation and amination reactions, respectively. The role of planar chirality in asymmetric reactions has been examined, and decisive effects on enantioselectivity as well as the control of absolute configuration in palladium-catalyzed allylic alkylation and amination reactions were observed. To clarify why and how the planar chirality governed the stereochemical outcome, X-ray crystallographic structures of η³-diphenylallyl Pd complexes, ¹H NMR, ³¹P NMR spectra of palladium dichloride complexes, and η³ -diphenylallyl Pd complexes of three 1,1′-P,N-ferrocene ligands were analyzed with the aid of COSY and 2D NOESY experiments. All results led to the conclusion that planar chirality influences the stereochemical outcome by changing or even inverting the ratio of two rotamers because of the steric interaction between a planar chiral group and the coordination site.

Full text of DOI:10.1021/ja002657q

6508
J. Am. Chem. Soc. 2001, 123, 6508-6519
Importance of Planar Chirality in Chiral Catalysts with Three Chiral
Elements: The Role of Planar Chirality in 2′-Substituted
1,1′-P,N-Ferrocene Ligands on the Enantioselectivity in Pd-Catalyzed
Allylic Substitution
Wei-Ping Deng,† Shu-Li You,† Xue-Long Hou,*,† Li-Xin Dai,† Yi-Hua Yu,‡ Wei Xia,‡ and
Jie Sun†
Contribution from the Laboratories of Organometallic Chemistry and Analytical Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
ReceiVed July 19, 2000
Abstract: A series of novel planar chiral 2′-substituted 1,1′-P,N-ferrocene ligands 9-11, 14, and 16 were
prepared with diastereopurity >99:1 and found to be effective in asymmetric allylic alkylation and amination
reactions. Ligand 14 furnished the highest enantiomeric excess, 98.5% and 96.5% ee in alkylation and amination
reactions, respectively. The role of planar chirality in asymmetric reactions has been examined, and decisive
effects on enantioselectivity as well as the control of absolute configuration in palladium-catalyzed allylic
alkylation and amination reactions were observed. To clarify why and how the planar chirality governed the
1
stereochemical outcome, X-ray crystallographic structures of η3-diphenylallyl Pd complexes, H NMR, 31P
NMR spectra of palladium dichloride complexes, and η3-diphenylallyl Pd complexes of three 1,1′-P,N-ferrocene
ligands were analyzed with the aid of COSY and 2D NOESY experiments. All results led to the conclusion
that planar chirality influences the stereochemical outcome by changing or even inverting the ratio of two
rotamers because of the steric interaction between a planar chiral group and the coordination site.
Introduction
intensive attention.8 Although many excellent results were
derived from planar chiral ferrocene ligands, the role of planar
chirality was still unclear. Some examples showed that the planar
chirality had a significant effect on the enantioselectivity,9 while
in other examples it was not so apparent.10a,b To date, there are
only a few reports of attempts to investigate the role of planar
Catalytic enantioselective reactions have attracted great
interest among synthetic chemists in recent years, and many
efforts in preparing efficient ligands have been made.1 It is
noteworthy that most of the chiral ligands currently used consist
of central chirality and/or axial chirality. Since the pioneering
work of Hayashi and co-workers,2a the use of planar chiral
ferrocene ligands has grown2 rapidly, culminating recently in
two industrial asymmetric hydrogenation processes.3 Lately,
several new approaches have appeared for the introduction of
planar chirality to ferrocene, key contributors being Sammakia,4a
Richards,4b Uemura4c (oxazoline system), Kagan5 (acetal and
sulfate system), Enders6 (SAMP system), and Snieckus7 (sparteine
system). Ferrocene ligands have therefore received extremely
(5) (a) Riant, O.; Samuel, O.; Kagan, H. B. J. Am. Chem. Soc. 1993,
115, 5835. (b) Rebie`re, F.; Riant, O.; Ricard, L.; Kagan, H. B. Angew.
Chem., Int. Ed. Engl. 1993, 32, 568. (c) Riant, O.; Samuel, O.; Flessner,
T.; Taudien, S.; Kagan, H. B. J. Org. Chem. 1997, 62, 6733.
(6) Enders, D.; Peters, R.; Lochtman, R.; Runsink, J. Synlett 1997, 1462.
(7) Tsukazaki, M.; Tinkl, M.; Roglans, A.; Chapell, B. J.; Taylor, N. J.;
Snieckus, V. J. Am. Chem. Soc. 1996, 118, 685.
(8) For recent ferrocene-based examples, see: (a) Nishibayashi, Y.;
Segawa, K.; Arikawa, Y.; Ohe, K.; Hidai, M.; Uemura, S. J. Organomet.
Chem. 1997, 546, 381. (b) Sammakia, T.; Stangeland, E. L. J. Org. Chem.
1997, 62, 6104. (c) Ahn, K. H.; Cho, C.-W.; Park, J.; Lee, S. Tetrahedron:
Asymmetry 1997, 8, 1179. (d) Schwink, L.; Knochel, P. Chem. Eur. J. 1998,
4, 950. (e) Riant, O.; Argouarch, G.; Guillaneux, D.; Samuel, O. Kagan,
H. B. J. Org. Chem. 1998, 63, 3511. (f) Perea, J. J. A.; Borner, A.; Knochel,
P. Tetrahedron Lett. 1998, 39, 8073. (g) Zhang, W.; Shimanuki, T.; Kida,
T.; Nakatsuji, Y.; Ikeda, I. J. Org. Chem. 1999, 64, 6247. (h) Iftime, G.;
Daran, J.-C.; Manoury, E.; Balavoine, G. G. A. Angew. Chem., Int. Ed.
1998, 37, 1698. (i) Zhang, W.; Yoneda, Y.; Kida, T.; Nakatsuji, Y.; Ikeda,
I. J. Organomet. Chem. 1999, 574, 19. (j) Ireland, T.; Almena Perea, J.;
Knochel, P. Angew. Chem., Int. Ed. 1999, 38, 1457. (k) Deng, W.-P.; Hou,
X.-L.; Dai, L.-X. Tetrahedron: Asymmetry 1999, 10, 4689.
* To whom correspondence should be addressed. E-mail: xlhou@
pub.sioc.ac.cn.
† Laboratory of Organometallic Chemistry.
‡ Laboratory of Analytical Chemistry.
(1) Review: (a) Ojima, I., Ed. Catalytic Asymmetric Synthesis, 2nd ed.;
Wiley-VCH: New York, 2000. (b) Noyori, R. Asymmetric Catalysis in
Organic Synthesis; Wiley: New York, 1994. (c) Brunner, H.; Zettlmeier,
W. Handbook of EnantioselectiVe Catalysis with Transition Metal Com-
pounds; VCH: Weinheim, 1993. (d) Jacobsen, E. N., Pfaltz, A., Yamamoto,
H., Eds. ComprehensiVe Asymmetric Catalysis; Springer: Berlin, 1999; Vol.
1-3. (e) Lin, G.-Q.; Li, Y.-M.; Chan, A. S. C. Principles and Applications
of Asymmetric Synthesis; Wiley: New York, 2001.
(9) (a) Hayashi, T.; Konishi, M.; Fukushima, M.; Mise, T.; Kagotani,
M.; Tajika, M.; Kumada, M. J. Am. Chem. Soc. 1982, 104, 180. (b) Bolm,
C.; Fernandez, K. M.; Seger, A.; Raabe, G.; Gunther, K. J. Org. Chem.
1998, 63, 3, 7860. (c) Zhou, X.-T.; Lin, Y.-R.; Dai, L.-X.; Sun, J.; Xia,
L.-J.; Tang, M.-H. J. Org. Chem. 1999, 64, 1331.
(2) Reviews: (a) Togni, A., Hayashi, T., Eds. Ferrocenes; VCH:
Weinheim, 1995, and references therein. (b) Richards, C. J.; Locke, A. J.
Tetrahedron: Asymmetry 1998, 9, 2377.
(3) (a) Togni, A. Angew. Chem., Int. Ed. Engl. 1996, 35, 1475. (b) Blaser,
H.-U.; Spindler, F. Chimia 1997, 51, 297. (c) Imwinkelried, R. Chimia 1997,
51, 300.
(4) (a) Sammakia, T.; Latham, H. A. J. Org. Chem. 1995, 60, 6002. (b)
Richards, C. J.; Damalidis, T.; Hibbs, D. E.; Hursthous, M. B. Synlett 1995,
74. (c) Nishibayashi, Y.; Uemura, S. Synlett 1995, 79. (d) Park, J.; Lee, S.;
Ahn, K H.; Cho, C.-W. Tetrahedron Lett. 1995, 36, 7263.
(10) (a) You, S.-L.; Zhou, Y.-G.; Hou X.-L.; Dai, L.-X.Chem. Commun.
1998, 2765. (b) Du, X.-D.; Dai, L.-X.; Hou, X.-L.; Xia, L.-J.; Tang, M.-H.
Chin. J. Chem. 1998, 16, 90. (c) Dai, L.-X.; Hou, X.-L.; Deng, W.-P.; You,
S.-L.; Zhou, Y.-G. Pure Appl. Chem. 1999, 71, 1401. (d) You, S.-L.; Hou
X.-L.; Dai, L.-X. Tetrahedron: Asymmetry 2000, 11, 1495. (e) You, S.-L.;
Hou, X.-L.; Dai, L.-X.; Cao, B.-X.; Sun, J. Chem. Commun. 2000, 1933.
(f) You, S.-L.; Hou, X.-L.; Dai, L.-X.; Zhu, X.-Z. Org. Lett. 2001, 3, 149.
10.1021/ja002657q CCC: $20.00 © 2001 American Chemical Society
Published on Web 06/15/2001

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6509
chirality on the stereochemical outcome in asymmetric syn-
thesis.9b,10a Recently, the work of Fu and co-workers11 on the
single planar chiral ferrocene ligands revealed that they are
highly efficient catalysts for asymmetric reactions. There is an
urgent need to clarify the contradictory results on the role of
planar chirality in ferrocene systems for the purpose of new
efficient ligand design. In the literature, most ferrocene-based
works dealt with 1,2-disustituted ferrocene ligands having two
donor groups on the same Cp ring, e.g., 1,4b 2,10a and 3.9b
Recently, Ikeda,12a,b Ahn,12c and Knochel13 reported the new
1,1′-disubstituted ferrocenyl ligands 4, 5, and 6. From these
catalysts, good enantioselectivities were obtained for several
asymmetric reactions. However, the introduction of planar
chirality has not been reported for this 1,1′-disubstituted
ferrocene system prior to now.
Scheme 1
Scheme 2a
Ligand 4 has no planar chirality on the ferrocene backbone.
However, coordination with a metal nevertheless leads to the
formation of two rotamers, A and B (Scheme 1), due to the
rotation of the Cp rings.12b This newly formed chirality is
assigned as axial chirality.
Furthermore, it is worthy of note that, after introduction of
planar chirality to ligand 4 and coordination with a metal, three
kinds of chiral elements (central, axial, and planar chirality) in
one catalyst will be installed. This interesting situation prompted
us to explore the enantioselective ability of this three-chiral-
elements catalyst in asymmetric reactions. As a part of our
program9c,10 aimed at the design of chiral ligands and their
applications to asymmetric synthesis, we synthesized several
novel planar chiral 1,1′-P,N-2′-substituted ferrocene ligands,
9-11, 14, and 16. A preliminary communication14 reported that
these ligands were effective in Pd-catalyzed allylic alkylation
reactions with excellent yield and excellent enantioselectivity.
It was also apparent that planar chirality is decisive in exerting
control over both absolute configuration and enantiomeric
excess. In this report, we would like to answer the following
three questions: (1) Are all three of these elements of chirality
necessary for excellent enantioselectivity? (2) What is the role
of each chirality on the stereo outcome? (3) Which chirality is
more influential in the enantioselective control of the products?
a Conditions: (a) n-BuLi/THF, -78 °C. (b) Ph2PCl, 78%. (c) n-BuLi/
Et2O, TMEDA, -78 °C. (d) E+ (MeI, TMSCl, or n-Bu3SnCl). (e) E+
(MeI or BrCF2CF2Br). (f) TBA/THF, reflux. (g) TMSCl, 73%.
In the meantime, we would like to provide detailed experimental
evidence and extend the scope of application to allylic amina-
tion.
Results and Discussion
Synthesis of Ligands. As shown in Scheme 2, ferrocenyl-
oxazoline derivatives 7a-c, synthesized according to Bryce’s
method,14,15 were treated with n-BuLi in THF at -78 °C for
0.5 h, followed by trapping with Ph2PCl to afford 1-diphenyl-
phosphino-1′-oxazolinylferrocenes 8a-c. Directed diastereo-
selective ortho-lithiation of 8a according to Richards’s proce-
dure,16 followed by treatment with an electrophile (MeI, TMSCl,
or Bu3SnCl), gave 2′-substituted compound 9, 10, or 11,
respectively. Compound 9 was again lithiated in THF at -78
°C for 2 h, followed by trapping with an electrophile (MeI or
BrCF2CF2Br), to afford ferrocene derivatives 12 and 13.
Conversion of 12 and 13 to 14 and 15, respectively, was
accomplished by protodesilylation with TBAF in 96% and 85%
yields. A bromo-lithium exchange of 15 followed by quenching
of the resulting lithium salt with TMSCl then furnished 16. The
diastereopurity of each of these planar chiral compounds as
(11) (a) Ruble, J. C.; Tweddell, J.; Fu, G. C. J. Org. Chem. 1998, 63,
2794. (b) Qiao, S.; Fu, G. C. J. Org. Chem. 1998, 63, 4168. (c) Garrett, C.
E.; Fu, G. C. J. Am. Chem. Soc. 1998, 120, 7479. (d) Shintani, R.; M.-C.
Lo, M.; Fu, G. C. Org. Lett. 2000, 2, 3695.
(12) (a) Zhang, W.; Adachi, Y.; Hirao, T.; Ikeda, I. Tetrahedron:
Asymmetry 1996, 7, 451. (b) Zhang, W.; Yoneda, Y.; Kida, T.; Nakatsuji,
Y.; Ikeda, I. Tetrahedron: Asymmetry 1998, 9, 3371. (c) Park, J.; Quan,
Z.; Lee, S.; Ahn, K. H.; Cho, C.-W. J. Organomet. Chem. 1999, 584, 140.
(d) The 91% ee value of compound 22 by using ligand 8a was obtained in
our laboratory, which is consistent with Ikeda’s result (ref 12b). However,
Ahn et al. reported that 99% ee was obtained by using the same ligand (ref
12c).
1
determined from 300 MHz H NMR was >99:1. Ligands 14
and 16 have a sense of planar chirality opposite to that of ligands
10 and 9.
(13) Schwink, L.; Ireland, T.; Pu¨ntener, K.; Knochel, P. Tetrahedron:
Asymmetry 1998, 9, 1143.
(14) Deng, W.-P.; Hou, X.-L.; Dai, L.-X.; Yu, Y.-H.; Xia, W. Chem.
Commun. 2000, 285.
(15) Chesney, A.; Bryce, M. R.; Chubb, R. W. J.; Batsanov, A. S.;
Howard, J. A. K. Synthesis 1998, 413.
(16) Richards, C. J.; Mulvaney, A. W. Tetrahedron: Asymmetry 1996,
7, 1419.

6510 J. Am. Chem. Soc., Vol. 123, No. 27, 2001
Deng et al.
Scheme 3a
Table 1. Effect of Different Planar Chiral Ligands on
Enantioselectivity and Configuration of the Product in
Palladium-Catalyzed Allylic Alkylationa
entry
ligand
yield (%)d
ee value (%)e
configurationf
1
2b
3
(S)-8a
(S)-8a
99
98
98
99
98
99
99
99
99
99
98
98
99
99
98
98
91.0
92.8
69.7
64.0
34.2
98.5
98.2
87.8
98.6
97.8
83.3
77.7
79.4
81.9
79.6
84.1
S
S
R
R
R
S
S
S
S
S
R
R
R
R
S
(S,Sp)-9
(S,Sp)-9
(S,Rp)-10
(S,Sp)-14
(S,Sp)-14
(S,Sp)-14
(S,Rp)-16
(S,Rp)-16
(S,Sp)-11
(S,Sp)-11
(Sp)-20
4b
5b
6b
7
8c
9b
10
11
12b
13
14
15
16
(Sp)-22
(Rp)-20
(Rp)-22
S
a Conditions: (a) (1) TFA/H2O/Na2SO4; (2) Ac2O/Py. (b) MeONa/
MeOH, reflux. (c) Amino alcohol (neat)/Na. (d) Et3N/CH3SO2Cl/DCM.
a Molecular ratio: [Pd(η3-C3H5)Cl]2/ligand/23/dimethyl malonate/
BSA/KOAc ) 2.5/5.2/100/300/300/5. b No KOAc was used. c 10 equiv
of KOAc was used vs ligand. d Isolated yield. e The ee value for 24
was determined by HPLC analysis using a Chiralcel OD column.
f Configurations were assigned by comparison with the sign of optical
rotation.
Scheme 4
As can be seen in Table 1, a dramatic change of the
enantioselectivity of the reaction was observed with 8a and 9;
i.e., the enantiomeric excess of the reaction product 24 changed
from 91% with S configuration by using ligand 8a to 69.7%
with R configuration by using ligand 9 (entries 1and 3). It
therefore appears that the effect of the newly introduced TMS
group is significant. This exciting result encouraged us to probe
the effect of the newly introduced group with opposite planar
chirality, which may result in the increase of ee values while
keeping the same absolute configuration of the product.
Therefore, (S,Sp)-14 was subjected to the same reaction. As
expected, a remarkable improvement of the ee value (entry 6,
98.5%, S configuration) was revealed. This result indicates that
planar chirality is significant in the control of the stereochemical
outcome. In an attempt to support our reasoning, ligands (Sp)-
20 and (Sp)-22 with only planar chirality were tested for the
same reaction. Good enantioselectivities (entries 13 and 14,
79.5% and 81.5% ee) were observed with both ligands, which
To clarify the role of planar chirality on stereochemical
outcome, we also synthesized ligands (Sp)-20 and (Sp)-22, which
contained only planar chirality. As shown in Scheme 3,
compound (S,Sp)-9 was converted into the corresponding ester
(S,Sp)-17 by employing Meyers’s procedure.17 The correspond-
ing enantiomerically pure methyl ester (Sp)-18 was easily formed
in 93% yield from (S,Sp)-17 through treatment with NaOMe.
Compound 18 was allowed to react in neat amino alcohols at
100 °C for 1-1.5 h in the presence of a small amount of sodium
metal, leading to the corresponding amides (Sp)-19 and (Sp)-21
in moderate yields. Further conversion of (Sp)-19 and (Sp)-21
was accomplished via the corresponding mesylate intermediates,
which were cyclized in situ to our targets (Sp)-20 and (Sp)-22
in moderate yields. For the sake of comparison, the correspond-
ing (Rp)-20 and (Rp)-22 were also prepared (Scheme 4).
Asymmetric Allylic Alkylation. Chiral P,N-ligands were
proved to be effective in several kinds of metal-catalyzed
asymmetric reactions,18 especially in palladium-catalyzed allylic
substitution.18a-k In particular, ligand 8a gave 91% ee in
palladium-catalyzed allylic substitution.12b-d In our previous
work, we studied the role of planar chirality of 1,2-N,S-ferrocene
ligands in the palladium-catalyzed allylic alkylation.10a To
investigate the role of the planar chirality of our new kind of
1,1′-P,N-2′-disubstituted ferrocene ligands in metal-catalyzed
asymmetric reactions, Pd-catalyzed allylic alkylation was also
chosen as a model reaction (eq 1).19 The results are summarized
in Table 1.
(17) Warshawsky, A. M.; Meyers, A. I. J. Am. Chem. Soc. 1990, 112,
8090.
(18) Selected papers for P,N-chelating ligands: (a) Matt, P. v.; Pfaltz,
A. Angew. Chem., Int. Ed. Engl. 1993, 32, 566. (b) Sprinz, J.; Helmchen,
G. Tetrahedron Lett. 1993, 34, 1769. (c) Dawson, G. J.; Frost, C. G.;
Williams, J. M. J.; Coote, S. J. Tetrahedron Lett. 1993, 34, 3149. (d) Kubota,
H.; Koga, K. Tetrahedron Lett. 1994, 35, 6689. (e) Mino, T.; Imiya, W.;
Yamashita, M. Synlett 1997, 583. (f) Cahill, J. P.; Guiry, P. J. Tetrahe-
dron: Asymmetry 1998, 9, 4301. (g) Vyskocˇil, Sˇ.; Smrcˇina, M.; Hanusˇ,
V.; Pola´sˇek, M.; Kocˇovsky´, P. J. Org. Chem. 1998, 63, 7738. (h) Gilbertson,
S. R.; Chang, C.-W. T. J. Org. Chem. 1998, 63, 8424. (i) Kudis, S.;
Helmchen, G. Angew. Chem., Int. Ed. 1998, 37, 3047. (j) Schnyder, A.;
Hintermann, L.; Togni, A. Angew. Chem., Int. Ed. Engl. 1995, 34, 931. (k)
Lightfoot, A.; Schnider, P.; Pfaltz, A. Angew. Chem., Int. Ed. 1998, 37,
2897. (l) Loiseleur, O.; Meier, P.; Pfaltz, A. Angew. Chem., Int. Ed. Engl.
1996, 35, 200. (m) Nishibayashi, Y.; Segawa, K.; Ohe, K.; Uemura, S.
Organometallics 1995, 14, 5486. (n) Takei, I.; Nishibayashi, Y.; Arikawa,
Y.; Uemura, S.; Hidai, M. Organometallics 1999, 18, 2271. (o) Loiseleur,
O.; Hayashi, M.; Keenan, M.; Schmees, N.; Pfaltz, A. J. Organomet. Chem.
1999, 576, 16.
(19) Recent examples for Pd-catalyzed allylic alkylation: (a) Koning,
B.; Meetsma, A.; Kellogg, R. M. J. Org. Chem. 1998, 63, 5533. (b) Evans,
D. A.; Campos, K. R.; Tedrow, J. S.; Michael, F. E.; Gagne´, M. R. J. Org.
Chem. 1999, 64, 2994. (c) Yonehara, K.; Hashizume, T.; Mori, K.; Ohe,
K.; Uemura, S. J. Org. Chem. 1999, 64, 9374. (d) Gilbertson, S. R.; Xie,
D. Angew. Chem., Int. Ed. 1999, 38, 2750. (e) Hou, D.-R.; Burgess, K.
Org. Lett. 1999, 1, 1745. (f) Adams, H.; Anderson, J. C.; Cubbon, R.; James,
D. S.; Mathias, J. P. J. Org. Chem. 1999, 64, 8256.

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6511
Table 2. Enantioselective Allylic Aminationa
Scheme 5. Proposed Isomerism of PdCl2(CH3CN)2
Complexes with Ferrrocene Ligands 8a, 9, and 16
ee (%)c
time (h) solvent yield (%)b (configuration)d
entry
ligand
1
2
3
4
5
6
7
8
9
(S,Sp)-14
(S,Sp)-14
(S,Sp)-14
(S,Sp)-14
(S,Sp)-14
(S,Sp)-14
(S)-8a
(S,Sp)-9
(Sp)-20
(Sp)-22
8
6
6
3
3
1
1.5
8
0.5
1
THF
97
99
96
99
98
99
96
25
99
99
90.8 (R)
92.4 (R)
92.6 (R)
88.5 (R)
94.5 (R)
96.5 (R)
89.7 (R)
32.3 (S)
67.3 (S)
89.5 (S)
DME
dioxane
CH3CN
DCM
DCE
DCE
DCE
DCE
DCE
10
a Molecular ratio: [Pd(η3-C3H5)Cl]2/ligand/23/BnNH2 ) 2.5/5.2/100/
200. b Isolated yields. c The ee value for 31 was determined by HPLC
analysis using a Chiralcel OJ column. d Configurations were assigned
by comparison with the sign of optical rotation.
indicate that the planar chirality should be decisive for the
enantioselectivity. Furthermore, the antipodes of (Sp)-20 and
(Sp)-22, (Rp)-20 and (Rp)-22, also afford good enantioselectivities
(entries 15 and 16, 79.6% and 84.1% ee), as expected, but in
the R configurations. This finding further indicates the decisive
role of planar chirality in the control of enantioselectivity. To
study the steric effect of the 2′-substituted group, (S,Sp)-10 and
(S,Rp)-16 were also tested. Reasonable results were obtained to
show a relationship between the steric bulkiness of the 2′-
substituent and enantioselectivity; i.e., the bulkier the group is,
the higher the ee value will be (viz. ligand 9 versus 10, entries
4 versus 5, and 14 versus 16, entries 6 versus 9). Consequently,
it is anticipated that replacing the TMS group with a sterically
bulkier 2′-substituent in ligand 9 will result in higher enanti-
oselectivity. Because of the low electrophilicity of the Ph3Si-
group, which could not be introduced onto the Cp ring, finally
Bu3Sn- was chosen for this purpose. Also as expected, a higher
ee value (83.3% ee of R configuration, entry 11) was obtained
when ligand 11 was used for this reaction.
Under the same reaction conditions, ligands (S)-8a and (S,Sp)-
9, which has a configuration of planar chirality opposite to that
of 14, as well as ligands (Sp)-20 and (Sp)-22 with only planar
chirality, were utilized for this reaction in order to test the role
of planar chirality. The results in Table 2 demonstrate that planar
chirality is also crucial to the stereochemistry of the reaction
product when the results for ligand (S,Sp)-9 are compared to
those for ligand (S,Sp)-14. Furthermore, ligands 20 and 22,
having only planar chirality, also afforded good enantioselec-
tivities (67.3% and 89.5%, respectively).
For the aforementioned allylic substitution reactions, all
ligands are effective, and among them 14 and 16 are the two
best ligands in terms of yield and enantioselectivity. Ligands
14 and 16 possess a (Sp)-Me group and a (Rp)-TMS group,
respectively, situated at the counterclockwise neighboring
position relative to the oxazoline group. As can be seen, 14
and 16 are better ligands than ligands 9 ((Sp)-TMS) and 10 ((Rp)-
Me), having TMS and Me groups situated at the clockwise
neighboring position. In addition, different dispositions of the
neighboring groups also afforded different absolute configura-
tions of the reaction products, i.e., S configuration from 14 and
16 but R configuration from 9 and 10. It has also been shown
that ligands (Sp)-20 and (Sp)-22 with only planar chirality also
lead to good enantioselectivity (vide supra) and R configuration
of the product, which is the same as that from ligand 9 that
bears also a (Sp)-TMS group. Accordingly, the (Rp)-20 and (Rp)-
22 afforded good ee values and S configuration of the product,
which is the same with ligand 16 bearing a (Rp)-TMS group.
Therefore, it appears that planar chiral groups play a decisive
role in controlling enantioselectivities as well as the absolute
configurations of the reaction products.
It was reported in the literature20 that the addition of KOAc
might sometimes increase the ee value. However, in our case,
this is not true for some ligands. For ligands 9 and 11 having
Sp planar chirality configuration, the addition of KOAc did
increase the ee value of reaction product (comparing entries 4
to 3 and 12 to 11). Whereas for ligand 8a and ligands 14 and
16, having opposite planar chirality, almost the same results
were obtained with the addition of KOAc (entries 2, 7, and 10).
The only difference between ligands 9 and 16 is the
disposition of a TMS group. (Sp)-TMS for 9 and (Rp)-TMS for
16, while the enantioselectivity of the reaction is 69.7% ee of
product with R configuration by using 9 and 97.8% ee of S
configuration for 16.
Asymmetric Allylic Amination. To extend the scope of the
application of these ligands, the most efficient ligand, (S,Sp)-
14, as mentioned above, was employed in asymmetric allylic
NMR Study of the Palladium Complexes of the Ligands.
On complexation of 8a (no planar chirality), 9 ((Sp)-TMS planar
chirality), and 16 ((Rp)-TMS planar chirality) with dichlorobis-
(acetonitrile)-palladium(II) in acetonitrile-d3, new axial chiralities
will be formed. The existing central and planar chiralities may
induce different ratios of the newly formed diastereomers, which
21
amination with benzylamine as a nucleophile.
1
could be examined with H and 31P NMR spectrometry. The
As shown in Table 2, different solvents obviously affected
the reactivity as well as the enantioselectivity. The best result
was obtained with 1,2-dichloroethane (DCE) as solvent, which
showed the highest reaction rate and the highest enantiomeric
excess of 96.5% (entry 6) in comparison with other solvents.
31P NMR spectrum of the complex of 8a with Pd (CH3CN)2Cl2
exhibited two major peaks in a ratio of 62:38, which was
consistent with the literature.12b The major one might be assigned
to diastereomer 26 (Scheme 5), which has less steric interaction
than 25. However, for the complex with 9, the ratio was changed
to 42:58, and thus the major peak might be assigned to
diastereomer 27, on the basis of the assumption that a (Sp)-
TMS group has a greater interaction on the coordination sites
(20) Trost, B. M.; Vranken, D. L. V. Chem. ReV. 1996, 96, 395.
(21) Review for allylic amination: Johannsen, M.; Jørgensen, K. A.
Chem. ReV. 1998, 98, 1689.

6512 J. Am. Chem. Soc., Vol. 123, No. 27, 2001
Deng et al.
1
Table 3. Selected 400 MHz H NMR Chemical Shifts of Allylic
confirms the exo configuration. [Nomenclature note: the endo
isomer is defined as the isomer that is the central allyl proton
and points to the ferrocene core]. Because the trans effect directs
nucleophilic addition to the allyl terminus trans to phosphorus
atom, the (S)-enantiomer should be the predominant product,
which is consistent with our experimental results. For this
rotamer, the W-type (8aa minor) would endure severe steric
interaction between the allylic phenyl group and the bisphenyl-
phosphino group as well as the i-Pr group. For complex 14a,
possessing a (Sp)-Me planar chiral group, there are also two
Protons in Complexes 8aa, 14a, and 9a in CD2Cl2
P- - -N
8aa (major)
14a (major)
9a (major)
9a (minor)
Ha
Hb
Hc
5.95
6.84
4.55a
6.02
6.81a
4.49
6.35
6.65
4.38a
6.10
6.65
4.59a
a Resonance could not be unequivocally assigned.
i
than an Pr group in 28. For the complex with 16 the ratio
became 22:1, which might be assigned to diastereomers 30
(major) and 29 (minor) (Scheme 5). From the 31P NMR data, it
is evident that the addition of a third group in a proper position
might change or even invert the ratio of the two rotamers. The
above ratios are in parallel with the ee values of the product,
i.e., 91% (S) for ligand 8a, 69.7% (R) for ligand 9, and 98.6%
(S) for ligand 16. Scheme 5 also illustrates that the linkage of
N-Pd-P is clockwise in the preferred isomers of 8a and 16.
For 9, the above linkage of the preferred isomer is, however,
altered to counterclockwise, and thus different absolute con-
figurations of the product were obtained (cf. Table 1). By this
consideration, a bulkier (Sp)-Bu3Sn group in ligand 9 should
further shift the equilibrium to the left. In agreement with this,
ligand (S,Sp)-11 increased the enantioselectivity of the reaction
(entries 3 versus 11 in Table 1).
1
diastereomeric intermediates observed from both H (Table 3)
and 31P NMR spectra, present in a ratio of 14:1. The major
diastereomer was assigned as exo-syn-syn (14a) configuration
by NOE study (partial 2D NOESY spectra of 8aa and 14a are
shown in Figure 1) similar to that of complex 8aa. This is also
consistent with the absolute configuration of the product of our
experimental result. Scheme 6 shows that complexes 8aa and
14a also possess similar exo-syn-syn configurations and
depicts that the (Sp)-Me in complex 14a is away from the
reaction site, which is consistent with its X-ray diffraction
structure (vide infra).
However, for complex 9a, in contrast to complexes 8aa and
14a, there are three diastereomeric intermediates, as shown in
1
both H (Table 3) and 31P NMR spectra, present in a ratio of
59:36:5. To answer the question as to which one of these three
intermediates belongs to the diastereomers due to axial chirality
and which one belongs to the exo or endo intermediate, the 1H
NMR spectra were carefully analyzed. The full assignment of
1H NMR of the 9a-A and 9a-B intermediates was facilitated
by observing the characteristic pattern (a doublet) of the allylic
proton Ha (or Ha′) trans to the phosphorus atom, and all other
allyl protons signals were deduced from COSY experiments.
However, it appears difficult to assign signals of the third
intermediate (9a-C). To characterize the two major components,
we carried out a 2D NOESY experiment (partial spectra of the
2D NOESY of 9a are shown in Figure 1). In the NOESY
spectrum, we observed three important NOEs for 9a-B: (1) a
NOE cross-peak between the two allylic terminal protons Ha′
and Hc′; (2) a NOE cross-peak between the ortho proton Hd′ of
the phenyl group on the allylic moiety and the Cp ring proton
H5′; (3) a NOE cross-peak between the allylic proton Ha′ trans
to phosphorus and the methine proton of the isopropyl group.
These results led us to assign an endo-syn-syn configuration
for 9a-B. In addition, the absence of NOE cross-signal between
the allylic proton Ha′ and the Cp ring proton H5′ indicates that
the minor diastereomer also possesses an endo configuration.
The major diastereomer, 9a-A, was assigned as exo-syn-syn
due to two key NOEs: (1) a strong NOE between the two allylic
terminal protons Ha and Hc; (2) the NOE between the allylic
terminal proton Ha trans to phosphorus and the Cp ring proton
H5. Furthermore, a section of the phase-sensitive NOESY
spectrum (Figure 1) showed that these two intermediates
exchanged on the time scale of the NOE and particularly the
interchange between the allylic proton Ha (or Ha′) of one
diastereomer with the allylic proton Hc′ (or Hc) of the other,
due to the rotation about the Pd-C bond in a σ-allyl
intermediate.22b,24 Therefore, these two major intermediates can
be unambiguously assigned as 9a-A (major) and 9a-B (minor)
as shown in Scheme 7. Similar to complex 14a, the (Sp)-TMS
of the two major components of complex 9a are also away from
the reaction site. Thus, the third tiny component may probably
The 31P NMR data revealed the ratio of diastereoisomers
during the formation of axial chirality by complexation with
Pd species. Furthermore, the enantioselectivity, especially the
chiral sense of induction, in this allylic substitution was also
related to the formation of endo or exo intermediates (W-type
or M-type) of η3-allylpalladium intermediates22 as well as the
trans effect of the ligating atom. It is known that the phosphorus
atom is a better π-acceptor than the nitrogen atom in an
π-allylpalladium complex bearing a P,N-bidentate ligand.23 This
preference consequently leads to a predominant nucleophilic
attack at the allylic carbon terminus trans to the Pd-P bond.
To comprehensively understand this enantioselective reaction,
solution NMR studies on the cationic palladium(II) 1,3-
diphenylallyl intermediates were carried out, in the hope of
getting some insight into the favored formation of endo or exo
diastereomers in a rotamer and/or the ratio of two rotamers.
The information garnered in this manner could be useful for
future rational ligand design in this area.
Initially, three cationic palladium complexes, [Pd (η3-1,3-
diphenylallyl) (S-8a)]SbF6 (8aa), [Pd (η3-1,3-diphenylallyl)
((S,Sp)-14)]SbF6 (14a), and [Pd (η3-1,3-diphenylallyl) ((S,Sp)-
9)]SbF6 (9a), were prepared according to a literature method.22a
For complex 8aa without planar chirality, two diastereomeric
1
intermediates were observed in both its H (Table 3) and 31P
NMR spectra, in a ratio of 14:1. The assignment of the major
diastereomer as exo-syn-syn (M-type) (8aa) configuration is
based on two critical NOEs experiments. First, a strong NOE
between the two allyl terminal protons Ha and Hc indicates a
syn-syn arrangement. The second key NOE, between the allyl
terminal proton Ha trans to phosphorus and Cp ring proton H2,
(22) (a) Hayashi, T.; Yamamoto, A.; Ito, Y.; Nishioka, E.; Miura, H.;
Yanagi, K. J. Am. Chem. Soc. 1989, 111, 6301. (b) Brown, J. M.; Hulmes,
D. I.; Guiry, P. J. Tetrahedron 1994, 50, 4493. (c) Togni, A.; Burckhardt,
U.; Gramlich, V.; Pregosin, P. S.; Salzman, R. J. Am. Chem. Soc. 1996,
118, 1031. (d) Helmchen, G.; Kudis, S.; Sennhenn, P.; Steinhagen, H. Pure
Appl. Chem. 1997, 69, 513. (e) Steinhagen, H.; Reggelin, M.; Helmchen,
G. Angew. Chem., Int. Ed. Engl. 1997, 36, 2108.
(23) (a) Åkermark, B.; Krakenberger, B.; Hansson, S.; Vitagliano, A.
Organometallics 1987, 6, 620. (b) Blo¨chl, P. E.; Togni, A. Organometallics
1996, 15, 4125. (c) Pen˜a-Cabrera, E.; Norrby, P.-O.; Sjogren, M.; Vitagliano,
A.; De Felice, V.; Oslob, J.; Ishii, S.; O’Neill, D.; Åkermark, B.; Helquist,
P. J. Am. Chem. Soc. 1996, 118, 4299.
(24) (a) Granberg, K. L.; Backvall, J. E. J. Am. Chem. Soc. 1992, 114,
6858. (b) Gogoll, A.; O¨ rnebro, J.; Grennberg, H.; Backvall, J. E. J. Am.
Chem. Soc. 1994, 116, 3631. (c) Breutel, C,; Pregosin, P. S.; Salzmann,
R.; Togni, A. J. Am. Chem. Soc. 1994, 116, 4067.

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6513
Figure 1. Sections of the phase-sensitive 1H 2D NOESY spectra of compounds 8aa (a), 14a (b), and 9a (c) and 2D exchange spectrum of 9a (d).
The square boxes mark the absence of cross-signals, which is also important for distinguishing between exo and endo configuration. The arrows
show the NOE between two protons (see also text).
Scheme 6
Scheme 7
be assigned as 9a-C. This result indicates that the introduction
of planar chirality actually leads to an inversion of the axial
chirality of complex 9a, and hence leads to the inversion of the
configuration of the reaction product. However, the low ee value
of 69.7% observed with ligand 9 is consistent with the low ratio
of its exo and endo diastereomers. The major intermediate 9a-A
is an endo-syn-syn isomer, which may lead to the product of
R configuration. This is also consistent with our result. In

6514 J. Am. Chem. Soc., Vol. 123, No. 27, 2001
Deng et al.
addition, the ee value of the product (69.7%) does not reflect
the isomeric distribution of the intermediate allyl complex,
which indicates that different isomers should display different
rates for nucleophilic attack according to Bosnich’s postulation.25
That is, the major component should be a more reactive one in
complex 9a. As a result, the 69.7% ee value of the product is
higher than the isomeric distribution (59% of 9a) of the
intermediate allyl complexes, and there should exist a fast
equilibrium among different components. A kinetic study on
complex 9a was done by monitoring its 31P NMR in order to
confirm our postulation. The procedure is described as fol-
lows: complex 9a was dissolved in CD2Cl2 at ambient tem-
perature (9a-A/9a-B/9a-C: 1.59/1/0.07), and then 0.3 equiv of
dimethylmalonate and 3 equiv of BSA were added, along with
a catalytic amount of KOAc. We used 31P NMR to detect the
ratio of the three components 9a-A/9a-B/9a-C: 5 min (1.47/
1/0.06), 15 min (1.45/1/0.05), 30 min (1.51/1/0.07), 1 h (1.54/
1/0.06), 3 h (1.61/1/0.09), 12 h (1.60/1/0.10). From the above
data, the change of the ratio is not apparent, and fast equilibra-
tion between the isomers might exit. After 12 h the product
was isolated, and the enantiomer excess was determined by
HPLC as 64.6% in R configuration, which is almost the same
result as that in entry 3 of Table 1. In addition, the assumption
that 9a-A is more more reactive could get support from 13C
NMR study. It has been reported that there is a correlation
between downfield shifts and the relative positive charge of the
carbon nucleus.27 With such a correlation, 13C NMR has been
used to predict the reactivity of the palladium allylic com-
plexes.28 For the two major components in 9a, 9a-A and 9a-B
in the ratio of 1.6:1, the terminal 13C allyl chemical shifts are
δ ) 110.8 (allyl carbon terminus trans to P) and 72.1 (trans to
N) for 9a-A (∆δ ) 38.7) and δ ) 103.2 (allyl carbon terminus
trans to P) and 71.7 (trans to N) for 9a-B (∆δ ) 31.5),
suggesting that 9a-A is a more electrophilic allyl terminus than
9a-B, and hence 9a-A is more reactive.
Figure 2. ORTEP view and atom numbering scheme for the cationic
complexes 14a.
X-ray Crystallographic Study of the Intermediate Com-
plex. From the NMR studies of the Pd complexes with ligands
and the intermediate complexes of the reaction, the role of the
planar chirality has almost been clarified. To obtain more in-
depth and perceivable knowledge of their stereochemical
interaction, the growth of single crystals of complexes 8aa, 9a,
and 14a has been attempted. Only a single crystal of complex
14a was obtained by slow evaporation from dichloromethane/
diethyl ether. In addition, a high-quality crystal of complex 8ca,
formed from the trans-1,3-diphenylpropenyl palladium chloride
dimer and ligand 8c in the presence of silver hexafluoroanti-
monate, was obtained by slow evaporation from dichlo-
romethane/diethyl ether. The X-ray crystal structure analysis
of 14a confirms its exo-syn-syn configuration, which is similar
to the result of solution NMR study. As shown in Figure 2, a
pseudo-square-planar geometry around palladium was observed,
and all bonding parameters fell in the expected ranges (see
Supporting Information). However, several characteristics are
worth noting. The planes of the two phenyl rings of the
diphenylphosphino group are nearly perpendicular to each other,
Figure 3. ORTEP view and atom numbering scheme for the cationic
complexes 8ca.
with one phenyl group directed downward and the other directed
toward the allylic moiety. There is an interaction between the
phenyl group at P and one of the allyl-phenyl groups (the spatial
distance between protons at C34 and C29 is 2.92 Å). Minimiza-
tion of this interaction is therefore the reason for the preference
of the exo (M-type) over the endo isomer. X-ray diffraction of
8ca shows that there are two molecules in an asymmetric unit
which have the same configuration (see Supporting Information).
As shown in Figure 3, the allyl ligand was also found to be of
exo-syn-syn configuration. The general geometric features of
the 8ca are very similar to those found for 14a (vide supra). In
addition, it was found that, for complex 14a, the spatial distance
between the proton H4 at C8 and the allyl proton Ha trans to
phosphorus is 2.46 Å; for complex 8ca, the spatial distance
(25) Auburn, P. R.; Mackenzie, P. B.; Bosnich, B. J. Am. Chem. Soc.
1985, 107, 2033.
(26) Hayashi, T.; Yamamoto, A.; Hagihara, T.; Ito, Y. Tetrahedron Lett.
1986, 27, 191-194.
(27) (a) Åkermark, B.; Zetterberg, K.; Hansson, S.; Krakenberger, B.;
Vitagliano, A. J. Organomet. Chem. 1987, 335, 133. (b) Macsa´ri, I.; Szabo´,
K. J. Organometallics 1999, 18, 701. (c) Malet, R.; Moreno-Man˜as, M.;
Parella, T.; Pleixats, R. Organometallics 1995, 14, 2463.
(28) (a) Macsa´ri, I.; Hupe, E.; Szabo´, K. J.J. Org. Chem. 1999, 64, 9547.
(b) Aranyos, A.; Szabo´, K. J.; Castan˜o, A. M.; Ba¨ckvall, J.-E. Organome-
tallics 1997, 16, 1058. (c) Moreno-Man˜as, M.; Pajuelo, F.; Parella, T.;
Pleixats, R. Organometallics 1997, 16, 205.

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6515
diphenyl-η3-allyl)dipalladium was prepared by a reported method.22a
The commercially available reagents were used as received without
further purification.
between the proton H7 at C8 and the allyl proton Ha trans to
phosphorus is 2.54 Å on average. This indicates that the two
similar protons, H4 and H7, on the Cp ring in two different
compounds are very close to the ligating center. Therefore, if a
Me group or a bulkier TMS group is situated at this position
instead of H7 (like ligand 9 or 11), there must be a strong steric
repulsion between the substituent and the ligating center, thereby
leading to the inversion of axial chirality in order to minimize
the steric repulsion. This finding can also well explain why the
planar chirality can control the enantioselectivity of the reaction
course and the absolute configuration of the reaction products.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]ferro-
cene, (S)-8a. Compound (S)-7a (188 mg, 0.5 mmol) was dissolved in
freshly distilled THF (4 mL) under argon and cooled to -78 °C. At
this temperature, n-BuLi (0.38 mL, 0.6 mmol, 1.6 M in n-hexane) was
added, and the resulting deep red solution was stirred for 20 min.
Chloro-diphenylphosphine (0.13 mL, 0.7 mmol) was then added, and
the resulting mixture was continually stirred and warmed to room
temperature over 30 min. The reaction mixture was diluted with ether
(20 mL), washed with saturated aqueous NaHCO3, and dried over
NaSO4. The solvent was removed under reduced pressure, and the
resulting residue was chromatographed on silica gel with ethyl acetate:
petroleum (1:4) as eluent to give 185 mg of (S)-8a (77%) as an orange
oil. [R]20D ) -84.5° (c 0.18, CHCl3); lit.12b,c [R]20D ) -85.0° (c 1.87,
Conclusion
In summary, we have synthesized a new kind of planar chiral
2′-substituted 1,1′-P,N-ferrocene ligands, 9-11, 14, and 16.
Ligands 14 and 16 are very effective in enantioselective Pd-
catalyzed allylic alkylation and amination reactions. These
ligands possess central and planar chirality and a new axial
chirality also formed during complexation with palladium. It is
evident that the planar chirality resulted from the central chirality
through a highly diastereoselective ortho-lithiation approach.
From the NMR and crystallographic evidence, it is clear that
the planar chirality of the newly introduced 2′-substituent
determines the rotamer ratio of the Pd complexes as well as
the stereo environment of the preferred rotamer. During the
allylic substitution reaction, the whole stereo environment
including central chirality shows a high preference for the
diastereo intermediates with exo-syn-syn conformation. Con-
sequently, high enantioselectivities are obtained in alkylation
reaction up to 98.6%, and in amination reaction up to 96.5%.
A similar result was observed in the asymmetric Heck reaction,29
which further indicates that the significant role of planar chirality
can be generalized to other reactions. In addition, this kind of
ligand is unique for its multichirality (central, planar, and axial
chirality on its coordination with Pd) and provides a new entry
for the design of novel ligands.30 Further study on exploring
the scope of asymmetric reactions with these promising ligands
is in progress.
1
CHCl3). H NMR: δ 0.91 (d, J ) 6.7 Hz, 3H), 0.99 (d, J ) 6.7 Hz,
3H), 1.84 (m, 1H), 3.94-4.05 (m, 2H), 4.13 (m, 2H), 4.20 (m, 2H),
4.27 (dd, J ) 8.0, 9.6 Hz, 1H), 4.39 (t, J ) 1.8 Hz, 2H), 4.68 (m, 2H),
7.31-7.39 (m, 10H). MS: m/z (relative intensity) 481 (M+, 100.0).
1-Diphenylphosphino-1′-[(R)-4-isopropyl-2,5-oxazolinyl]ferro-
cene, (R)-8a. Prepared from (R)-7a in 72% yield as an orange oil. [R]20
D
) 85° (c 0.29, CHCl3). 1H NMR: δ 0.90 (d, J ) 6.7 Hz, 3H), 0.99 (d,
J ) 6.7 Hz, 3H), 1.83 (m, 1H), 3.94-4.04 (m, 2H), 4.12 (m, 2H), 4.19
(m, 2H), 4.25 (dd, J ) 8.5, 9.1 Hz, 1H), 4.38 (t, J ) 1.5 Hz, 2H), 4.68
(m, 2H), 7.31-7.36 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ
-17.26. MS: m/z (relative intensity) 481 (M+, 100), 412 (51), 321 (41),
253 (23). IR (KBr): 2958, 1658, 1481, 1434, 1380, 1112, 1027.
HRMS: calcd for C28H28NOPFe 466.10228, found 466.09843.
1-Diphenylphosphino-1′-[(S)-4-benzyl-2,5-oxazolinyl]ferrocene,
(S)-8b. Compound 7b (212 mg, 0.5 mmol) was allowed to react
according to the procedure for (S)-8a to afford (S)-8b (193 mg, 73%)
1
as an orange oil. [R]20 ) -15.6° (c 0.32, CHCl3). H NMR: δ 2.68
D
(dd, J ) 9.0, 13.7 Hz, 1H), 3.19 (dd, J ) 4.7, 13.7 Hz, 1H), 4.03 (dd,
J ) 7.5, 8.2 Hz, 1H), 4.08-4.12 (m, 2H), 4.18-4.25 (m, 3H), 4.34 (t,
J ) 1.8 Hz, 2H), 4.35-4.49 (m, 1H), 4.68 (t, J ) 1.8 Hz, 2H), 7.20-
7.46 (m, 15H). MS: m/z (relative intensity) 529 (M+, 100), 412 (46),
328 (63), 253 (71), 91 (49). IR (KBr): 2926, 1655, 1480, 1434, 1116,
1026, 969, 744, 698, 504. Anal. Calcd for C32H28NOPFe: C, 72.58;
H, 5.33; N, 2.65. Found: C, 72.55; H, 5.32; N, 2.54.
1-Diphenylphosphino-1′-[(S)-4-tert-butyl-2,5-oxazolinyl]ferro-
cene, (S)-8c. Compound 7c (195 mg, 0.5 mmol) was allowed to react
according to the procedure for (S)-8a to afford (S)-8c (176 mg, 71%)
as a yellow solid. [R]20 ) -132.6° (c 0.35, CHCl3); lit.12b,c [R]20
)
Experimental Section
D
D
-131.8° (c 0.32, CHCl3).1H NMR: δ 0.92 (s, 9H), 3.87 (dd, J ) 7.7,
10.1 Hz, 1H), 4.09-4.24 (m, 6H), 4.40 (br, 2H), 4.65-4.68 (m, 2H),
7.30-7.40 (m, 10 H).
General Procedures. Melting points are uncorrected. 1H NMR
spectra were recorded on a Brucker AMX-400 (400 MHz) spectrometer,
and the chemical shifts were referenced to CHCl3 (δ 7.27) in CDCl3,
CHDCl2 (δ 5.32) in CD2Cl2, and CHD2CN (δ 1.93) in CDCN. 31P NMR
spectra were recorded on a Bruker AMX-400 (162 MHz) spectrometer,
and the chemical shifts were referenced to external 85% H3PO4. 13C
NMR spectra were recorded on a Bruker AMX-400 (100.6 MHz)
spectrometer, and the chemical shifts were referenced to CHDCl2 in
CD2Cl2. Standard pulse sequences were employed for 1H 2D NOESY
and 1H-1H and 13C-1H correlations studies. Optical rotation was
measured using a Perkin-Elmer 241 MC polarimeter with a thermally
jacketed 10 cm cell at 25 °C (concentration c given as grams per 100
mL). IR spectra were recorded in KBr and measured in inverse
centimeters, using a Shimadzu IR-440 infrared spectrophotometer. Mass
spectra and high-resolution mass spectra were taken using HP5989A
and Finnigan MAT mass spectrometers, respectively. Elemental
analyses were performed on a Foss-Heraeus Vario EL instrument.
Enantiomeric excess (ee) values were determined by chiral HPLC on
a Chiralcel OD or OJ column.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Sp)-
(trimethylsilyl)-ferrocene, (S,Sp)-9. A solution of 8a (3.13 g, 6.5 mmol)
and TMEDA (1.2 mL, 8.0 mmol) in ether (40 mL) under argon was
cooled to -78 °C. To this solution was added dropwise n-BuLi (5.0
mL, 8.0 mmol). After the resultant solution was stirred at -78 °C for
2 h, TMSCl (1.2 mL, 9.6 mmol) was added, and the dry ice bath was
removed. The resulting mixture was continually stirred for 20 min,
and then quenched with saturated NaHCO3, diluted with ether, washed
with brine, dried over MgSO4, filtered, and evaporated under reduced
pressure. The resulting residue was purified by column chromatography
with ethyl acetate:petroleum (1:20) as an eluent to afford 3.34 g of
compound (S,Sp)-9 as an orange oil (yield, 93%). [R]20D ) 64° (c 0.20,
1
CHCl3). H NMR: δ 0.26 (s, 9H), 0.90 (d, J ) 6.7 Hz, 3H), 1.01 (d,
J ) 6.7 Hz, 3H), 1.78 (m, 1H), 3.85-4.02 (m, 2H), 4.10-4.17 (m,
3H), 4.18 (t, J ) 2.5 Hz, 1H), 4.27 (td, J ) 7.3, 1.4 Hz, 1H), 4.34 (m,
1H), 4.39 (m, 1H), 4.79 (s, 1H), 7.24-7.40 (m, 10H). 31P NMR (161.92
MHz, CDCl3): δ -17.17. MS: m/z (relative intensity) 553 (M+, 38),
538 (33), 368 (100), 353 (65), 268 (55), 149 (53). IR (KBr): 2957,
1656, 1434, 1242, 1154, 990, 836, 742, 697, 503. Anal. Calcd for
C31H36NOSiPFe: C, 67.27; H, 6.55; N, 2.53. Found: C, 67.42; H, 6.68;
N, 2.40.
All the reactions were performed under a dry argon atmosphere.
Tetrahydrofuran (THF) and diethyl ether were freshly distilled from
sodium under a dry argon atmosphere. Dichloromethane, TMEDA, and
triethylamine were distilled from calcium hydride. Bis(µ-chloro)(1,3-
1-Diphenylphosphino-1′-[(R)-4-isopropyl-2,5-oxazolinyl]-2′(Rp)-
(trimethylsilyl)-ferrocene, (R,Rp)-9. Prepared from (R)-8a in 92% yield
as an orange oil. [R]20D ) -65° (c 0.16, CHCl3). 1H NMR: δ 0.26 (s,
(29) Deng, W.-P.; Hou, X.-L.; Dai, L.-X.; Dong, X.-W. Chem. Commun.
2000, 1483.
(30) Mun˜iz, K.; Bolm, C. Chem. Eur. J. 2000, 6, 2309.

6516 J. Am. Chem. Soc., Vol. 123, No. 27, 2001
Deng et al.
9H), 0.90 (d, J ) 6.7 Hz, 3H), 1.01 (d, J ) 6.7 Hz, 3H), 1.79 (m, 1H),
3.89-3.98 (m, 2H), 4.10-4.17 (m, 3H), 4.19 (t, J ) 2.3 Hz, 1H), 4.26
(t, J ) 8.0 Hz, 1H), 4.33 (m, 1H), 4.38 (m, 1H), 4.78 (s, 1H), 7.25-
7.35 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -16.98. MS: m/z
(relative intensity) 553 (M+, 100), 538 (72), 481 (39), 412 (20), 321
(33). IR (KBr): 2957, 1658, 1479, 1434, 1242, 988, 835. Anal. Calcd
for C31H36NOSiPFe: C, 67.27; H, 6.55; N, 2.53. Found: C, 67.66; H,
6.75; N, 2.57.
100 (79). IR (KBr): 2957, 2896, 1650, 1479, 1434, 1245, 1162, 985,
832, 742, 697. Anal. Calcd for C28H27NOPBrFe: C, 60.03; H, 4.86;
N, 2.50. Found: C, 60.12; H, 5.00; N, 2.47.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Sp)-
(trimethylsilyl)-5′(Sp)-(methyl)-ferrocene, (S,Sp,Sp)-12. Compound 9
(553 mg, 1.0 mmol) was dissolved in freshly distilled THF (8 mL)
under argon and cooled to -78 °C. At this temperature, n-BuLi (0.76
mL, 1.2 mmol, 1.6 M in n-hexane) was added, and the resulting deep
red solution was stirred for 2 h. Methyl iodide (0.2 mL, 3.0 mmol)
was then added, and the resulting mixture was continually stirred and
warmed to room temperature over 40 min. The reaction mixture was
diluted with ether (20 mL), washed with saturated aqueous NaHCO3,
and dried over NaSO4. The solvent was removed under reduced
pressure, and the resulting residue was chromatographed on silica gel
with ethyl acetate:petroleum (1:30) as eluent to give 482 mg of (S,Sp,Sp)-
12 (85%) as an orange oil. [R]20D ) 97° (c 0.24, CHCl3). 1H NMR: δ
0.21 (s, 9H), 0.89 (d, J ) 6.7 Hz, 3H), 1.02 (d, J ) 6.7 Hz, 3H), 1.75
(m, 1H), 2.06 (s, 3H), 3.87-4.02 (m, 4H), 4.10-4.13 (m, 2H), 4.21-
4.28 (m, 2H), 4.37 (s, 1H), 7.24-7.40 (m, 10H). 31P NMR (161.92
MHz, CDCl3): δ -17.06. MS: m/z (relative intensity) 567 (M+, 100),
552 (28), 171 (21), 73 (34). IR (KBr): 2957, 1649, 1434, 1244, 1064,
1027, 837, 742, 697. Anal. Calcd for C32H38NOSiPFe: C, 67.72; H,
6.75; N, 2.47. Found: C, 67.74; H, 6.99; N, 2.50.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Rp)-
(methyl)-ferrocene, (S,Rp)-10. Compound 8a (242 mg, 0.5 mmol) was
allowed to react according to the procedure for 9 to afford (S,Rp)-10
1
(193 mg, 78%) as an orange oil. [R]20 ) -162° (c 0.19, CHCl3). H
D
NMR: δ 0.93 (d, J ) 6.7 Hz, 3H), 1.0 (d, J ) 6.7 Hz, 3H), 1.81 (m,
1H), 2.14 (s, 3H), 3.94-4.07 (m, 4H), 4.10-4.13 (m, 2H), 4.20-4.26
(m, 2H), 4.30 (m, 1H), 4.54 (dd, J ) 1.5, 1.6 Hz, 1H), 7.25-7.48 (m,
10H). 31P NMR (161.92 MHz, CDCl3): δ -17.15. MS: m/z (relative
intensity) 495 (M+, 100), 426 (24), 321 (39), 294 (24), 267 (34), 171
(25). IR (KBr): 2958, 1653, 1480, 1434, 1070, 1025, 743, 697, 505.
Anal. Calcd for C29H30NOPFe: C, 70.31; H, 6.10; N, 2.83. Found: C,
70.62; H, 6.22; N, 2.82.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Sp)-
(methyl)-ferrocene, (S,Sp)-14. Under an argon atmosphere, a yellow
solution of 1 M TBAF in THF (20 mL) containing approximately 5%
H2O and compound 13 (567 mg, 1 mmol) was heated at reflux for 10
h. The resultant orange solution was evaporated in vacuo to low volume
and diluted with ether (30 mL), washed with water, dried over MgSO4,
filtered, and evaporated in vacuo. The resulting residue was column
chromatographed with ethyl acetate:petroleum (1:5) as eluent to give
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Rp)-
(bromo)-5′(Sp)-(trimethylsilyl)-ferrocene, (S,Rp,Sp)-13. Compound 9
(553 mg, 1.0 mmol) was dissolved in freshly distilled THF (8 mL)
under argon and cooled to -78 °C. At this temperature, n-BuLi (0.76
mL, 1.2 mmol, 1.6 M in n-hexane) was added, and the resulting deep
red solution was stirred for 2 h. 1,2-Dibromo-tetrafluoroethane (BrCF2-
CF2Br) (0.24 mL, 2.0 mmol) was then added, and the resulting mixture
was continually stirred and warmed to room temperature over 30 min.
The reaction mixture was diluted with ether (20 mL), washed with
saturated aqueous NaHCO3, and dried over Na2SO4. The solvent was
removed under reduced pressure, and the resulting residue was
chromatographed on silica gel with ethyl acetate:petroleum (1:30) as
(S,Sp)-14 as an orange oil (475 mg, 96%). [R]20 ) -59.0° (c 0.35,
D
1
CHCl3). H NMR: δ 0.90 (d, J ) 6.7 Hz, 3H), 0.98 (d, J ) 6.7 Hz,
3H), 1.91 (m, 1H), 2.10 (s, 3H), 3.87-4.33 (m, 9H), 4.56 (t, J ) 1.55
Hz, 1H), 7.24-7.39 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ
-17.25. MS: m/z (relative intensity) 495 (M+, 100), 427 (21), 321 (33),
267 (27), 171 (25). IR (KBr): 2958, 1652, 1480, 1434, 1070, 1025,
743, 697, 505. Anal. Calcd for C29H30NOPFe: C, 70.31; H, 6.10; N,
2.83. Found: C, 70.40; H, 6.09; N, 2.69.
eluent to give 506 mg of (S,Rp,Sp)-13 (80%) as an orange oil. [R]20
)
D
1
25° (c 0.19, CHCl3). H NMR: δ 0.23 (s, 9H), 0.91 (d, J ) 6.7 Hz,
3H), 1.04 (d, J ) 6.7 Hz, 3H), 1.81 (m, 1H), 3.92-4.16 (m, 3H), 4.17-
4.22 (m, 2H), 4.28-4.42 (m, 3H), 4.52 (m, 1H), 7.25-7.48 (m, 10H).
MS: m/z (relative intensity) 633 (M+, 100), 631 (91), 446 (54), 448
(54), 296 (56), 171 (50). IR (KBr): 2958, 1660, 1648, 1479, 1434,
1127, 1027, 977, 743, 697. Anal. Calcd for C31H35NOSiPBrFe: C,
58.87; H, 5.58; N, 2.21. Found: C, 58.78; H, 5.64; N, 2.13.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Sp)-
(tributylstannyl)-ferrocene, (S,Sp)-11. Compound 8a (242 mg, 0.5
mmol) was allowed to react according to the procedure for 9 to afford
(S,Sp)-11 (285 mg, 74%) as an orange oil. [R]20D ) 33° (c 0.27, CHCl3).
1H NMR: δ 0.80-1.20 (m, 21H), 1.25-1.42 (m, 6H), 1.48-1.62 (m,
6H), 1.82 (m, 1H), 3.85-4.0 (m, 2H), 4.07 (m, 2H), 4.13 (m, 1H),
4.25-4.36 (m, 4H), 4.81 (m, 1H), 7.25-7.40 (m, 10H). 31P NMR
(161.92 MHz, CDCl3): δ -17.35. MS: m/z (relative intensity) 714 (M+
- Bu, 100), 600 (20). IR (KBr): 2955, 2922, 1652, 1434, 1128, 1028,
984, 741, 697, 504. Anal. Calcd for C40H54NOPSnFe: C, 62.36; H,
7.07; N, 1.82. Found: C, 62.16; H, 7.16; N, 1.73.
1-Diphenylphosphino-1′-[N-acetyl-(S)-2-isopropyl-2-aminoethoxy-
carbonyl]-2′(Sp)-(trimethylsilyl)-ferrocene, (S,Sp)-17. A solution of
9 (5.53 g, 10 mmol) in freshly distilled THF (100 mL) was successively
treated with water (10 mL) and 74 g (0.52 mol) of sodium sulfate and
cooled to 0 °C before trifluoroacetic acid (4 mL) was added via a
syringe. The reaction mixture was stirred for 3 days at room temper-
ature, and then 20 g sodium sulfate was further added, and the reaction
mixture was filtered under argon. The organic solvent was removed in
vacuo to leave a dark oil, which was immediately dissolved in freshly
distilled dichloromethane (150 mL). The resulting solution was cooled
to 0 °C, and acetic anhydride (35 mL, 0.37 mol) was added followed
by pyridine (55 mL, 0.7 mol). Stirring was continued overnight, and
the resulting dark solution was quenched with 3 M HCl (750 mL),
washed with saturated sodium bicarbonate solution, and dried over
anhydrous MgSO4. The resulting deep red solution was removed in
vacuo and then purified by column chromatography with ethyl acetate:
petroleum (1:1) as an eluent to afford 3.34 g of ester amide (S,Sp)-17
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Rp)-
(trimethylsilyl)-ferrocene, (S,Rp)-16. Compound 15 (205 mg, 0.37
mmol) was dissolved in freshly distilled THF (4 mL) under argon and
cooled to -78 °C. At this temperature, n-BuLi (0.3 mL, 0.48 mmol,
1.6 M in n-hexane) was added, and the resulting deep red solution was
stirred for 20 min. TMSCl (0.07 mL, 0.56 mmol) was then added, and
the resulting mixture was continually stirred and warmed to room
temperature over 30 min. The reaction mixture was diluted with ether
(20 mL), washed with saturated aqueous NaHCO3, and dried over
NaSO4. The solvent was removed under reduced pressure, and the
resulting residue was chromatographed on silica gel with ethyl acetate:
petroleum (1:10) as eluent to give 149 mg of (S,Rp)-16 (73%) as an
orange oil. [R]20D ) -203° (c 0.19, CHCl3). 1H NMR: δ 0.24 (s, 9H),
0.91 (d, J ) 6.7 Hz, 3H), 0.99 (d, J ) 6.7 Hz, 3H), 1.75 (m, 1H),
3.80-3.99 (m, 2H), 4.10-4.20 (m, 4H), 4.25 (dd, J ) 7.9, 9.2 Hz,
1H), 4.32 (m, 1H), 4.37 (m, 1H), 4.78 (dd, J ) 1.4, 2.4 Hz, 1H) 7.25-
7.41 (m, 10H). MS: m/z (relative intensity) 553 (M+, 100), 538 (75),
469 (43), 171 (35), 149 (56), 73 (34), 43 (43). IR (KBr): 2957, 1656,
1434, 1242, 1154, 990, 836, 743, 697. Anal. Calcd for C31H36-
NOPSiFe: C, 67.27; H, 6.55; N, 2.53. Found: C, 67.64; H, 6.68; N,
2.49.
1-Diphenylphosphino-1′-[(S)-4-isopropyl-2,5-oxazolinyl]-2′(Rp)-
(bromo)-ferrocene, (S,Rp)-15. Under an argon atmosphere, a yellow
solution of 1 M TBAF in THF (16 mL) containing approximately 5%
H2O and compound 13 (500 mg, 0.79 mmol) was heated at reflux for
5 h. The resulting orange solution was evaporated in vacuo to low
volume, diluted with ether (30 mL), washed with water, dried over
MgSO4, filtered, and evaporated in vacuo. The resulting residue was
column chromatographed with ethyl acetate:petroleum (1:10) as an
eluent to give (S,Rp)-15 as an orange oil (377 mg, 85%). [R]20D ) -75.6
° (c 0.33, CHCl3). 1H NMR: δ 0.92 (d, J ) 6.8 Hz, 3H), 1.00 (d, J )
6.8 Hz, 3H), 1.85 (m, 1H), 4.03 (m, 1H), 4.08-4.15 (m, 2H), 4.18 (s,
1H), 4.21 (s, 1H), 4.30 (t, J ) 9.4 Hz, 1H), 4.38-4.48 (m, 3H), 4.62
(m, 1H), 7.31-7.39 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ
-18.10. MS: m/z (relative intensity) 561 (M+, 4), 559 (4), 142 (100),

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6517
as a yellow solid (yield, 54%). Mp: 85-86 °C. [R]20 ) -132.0° (c
4.23 (t, J ) 2.4 Hz, 1H), 4.36 (m, 1H), 4.49-4.52 (m, 2H), 6.55 (br,
1H), 7.32-7.49 (m, 10H). 31P NMR (161.92 MHz, CDCl3) δ -16.86.
MS: m/z (relative intensity) 529 (M+, 27), 514 (49), 496 (31), 484 (100),
456 (22), 321 (7). IR (KBr): 3358, 2953, 1738, 1529, 1479, 1434,
1244, 1160. HRMS: calcd for C28H32 NO2PSiFe 529.12890, found
529.12801.
1-Diphenylphosphino-1′-(2,5-oxazolinyl)-2′(Sp)-(trimethylsilyl)-
ferrocene, (Sp)-20. To a solution of amide (Sp)-19 (158 mg, 0.3 mmol)
and triethylamine (0.23 mL, 1.5 mmol) in dichloromethane (3 mL) was
added of methanesulfonyl chloride (0.02 mL, 0.3 mmol) at 0 °C. After
being stirred at room temperature for 5 h, the reaction solution was
washed with chilled water (10 mL) and then with brine, dried over
Na2SO4, and concentrated under reduced pressure to provide a residue
which was purified by column chromatography with ethyl acetate:
D
1
0.315, CHCl3). H NMR: δ 0.27 (s, 9H), 1.01 (d, J ) 6.8 Hz, 3H),
1.03 (d, J ) 6.8 Hz, 3H), 1.87 (s, 3H), 1.99 (m, 1H), 4.07-4.28 (m,
7H), 4.35 (m, 1H), 4.45 (s, 1H), 4.85 (m, 1H), 6.05 (d, J ) 8.9 Hz,
1H) 7.24-7.40 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -17.29.
MS: m/z (relative intensity) 613 (M+, 27), 486 (100), 442 (29), 321
(28), 170 (25), 86 (18). IR (KBr): 3285, 2960, 1714, 1649, 1550, 1434,
1247, 1157, 835, 696. Anal. Calcd for C33H40NO3PSiFe: C, 64.60; H,
6.57; N, 2.28. Found: C, 64.02; H, 6.46; N, 2.19.
1-Diphenylphosphino-1′-[N-acetyl-(R)-2-isopropyl-2-aminoethoxy-
carbonyl]-2′(Rp)-(trimethylsilyl)-ferrocene, (R,Rp)-17. Prepared from
(R,Rp)-7a in 52% yield as a yellow solid. Mp: 85-86 °C. [R]20
)
D
145.0° (c 0.59, CHCl3). 1H NMR: δ 0.28 (s, 9H), 1.01 (d, J ) 6.8 Hz,
3H), 1.03 (d, J ) 6.8 Hz, 3H), 1.88 (s, 3H), 1.99 (m, 1H), 4.08-4.29
(m, 7H), 4.35 (m, 1H), 4.46 (s, 1H), 4.86 (dd, J1 ) 1.2 Hz, J2 ) 1.9
Hz, 1H), 6.02 (d, J ) 8.9 Hz, 1H) 7.24-7.40 (m, 10H). 31P NMR
(161.92 MHz, CDCl3): δ -17.25. MS: m/z (relative intensity) 613 (M+,
28), 486 (100), 442 (23), 321 (11). IR (KBr): 3284, 2960, 1714, 1650,
1549, 1434, 1247, 1157, 835. HRMS: calcd for C33H40NO3PSiFe
613.18642, found, 613.18829.
petroleum (1:5) as eluent to afford oxazoline (Sp)-20 as a yellow solid
1
(86 mg, 56%). Mp: 82-83 °C. [R]20 ) 209° (c 0.14, CHCl3). H
D
NMR: δ 0.26 (s, 9H), 3.80-3.95 (m, 2H), 4.13-4.17 (m, 3H), 4.21
(t, J ) 2.4 Hz, 1H), 4.26-4.35 (m, 3H), 4.39 (m, 1H), 4.82 (s, 1H),
7.26-7.34 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -17.18. MS:
m/z (relative intensity) 511 (M+, 90), 496 (100), 497 (40), 326 (42),
171 (19). IR (KBr): 2954, 1656, 1434, 1243, 1137, 835, 743, 697,
502. Anal. Calcd for C28H30NOPSiFe: C, 65.75; H, 5.91; N, 2.74.
Found: C, 65.37; H, 6.01; N, 2.69.
1-Diphenylphosphino-1′-(methoxycarbonyl)-2′(Sp)-(trimethyl-
silyl)-ferrocene, (Sp)-18. To a solution of ester amide (S,Sp)-17 (613
mg, 1.0 mmol) in THF (15 mL) was added a sodium methoxide solution
prepared by the addition of sodium metal (1.0 g, 46 mmol) to methanol
(60 mL). After being stirred for 5 h at reflux temperature, the mixture
was neutralized with methanolic acetic acid, and the solvent was
removed by evaporation in vacuo. The residue was dissolved in
dicholromethane, and the resulting solution was washed with water
and then with brine and dried over MgSO4. After removal of the solvent,
the residue was purified by silica gel column chromatography with
ethyl acetate:petroleum (1:20) as eluent to afford ester (Sp)-18 as an
orange solid (465 mg, 93%). Mp: 108-109 °C. [R]20D ) 55.8° (c 0.425,
1-Diphenylphosphino-1′-(2,5-oxazolinyl)-2′(Rp)-(trimethylsilyl)-
ferrocene, (Rp)-20. Prepared from (Rp)-19 in 53% yield as a yellow
1
solid. Mp: 82-84 °C. [R]20 ) -208.0° (c 0.63, CHCl3). H NMR:
D
δ 0.26 (s, 9H), 3.88-3.92 (m, 2H), 4.14-4.20 (m, 4H), 4.27-4.33
(m, 3H), 4.39 (m, 1H), 4.81 (s, 1H), 7.26-7.34 (m, 10H). 31P NMR
(161.92 MHz, CDCl3): δ -17.28. MS: m/z (relative intensity) 511 (M+,
100), 496 (95), 468 (11), 452 (5), 326 (20). IR (KBr): 2947, 1644,
1477, 1431, 1166, 982, 752. HRMS: calcd for C28H30NOPSiFe
511.11833, found 511.11860.
1
CHCl3). H NMR: δ 0.27 (s, 9H), 3.76 (s, 3H), 4.14 (s, 1H), 4.19 (s,
1-Diphenylphosphino-1′-[N-(1,1-dimethyl-2-hydroxyethyl)amido]-
2′(Sp)-(trimethylsilyl)-ferrocene, (Sp)-21. A mixture of (Sp)-18 (170
mg, 0.34 mmol), 2,2-dimethyl-2-aminoethanol (2 mL), and a small
amount of sodium was heated at 100 °C for 1.5 h. The mixture was
diluted with dichloromethane and neutralized with acetic acid. The
neutralized solution was washed with water and then with brine and
dried over Na2SO4. After removal of the solvent, the residue was
purified by silica gel column chromatography with ethyl acetate:
petroleum (1:2) as eluent to afford amide (Sp)-21 as a yellow solid
(125 mg, 66%). Mp: 67-68 °C. [R]20D ) -115° (c 0.12, CHCl3). 1H
NMR: δ 0.28 (s, 9H), 1.39 (s, 6H), 3.63-3.65 (m, 2H), 3.98 (s, 1H),
4.09 (s, 1H), 4.17-4.18 (m, 2H), 4.33 (s, 1H), 4.44 (d, J ) 5.4 Hz,
2H), 5.17 (br, 1H), 6.41 (br, 1H), 7.24-7.44 (m, 10H). 31P NMR
(161.92 MHz, CDCl3): δ -17.18. MS: m/z (relative intensity) 557 (M+,
18), 527 (22), 484 (100), 485 (38), 321 (31), 285 (20), 171 (19). IR
(KBr): 3335, 2952, 1662, 1641, 1515, 834, 742, 696. Anal. Calcd for
C30H36 NO2PSiFe: C, 64.63; H, 6.51; N, 2.51. Found: C, 64.32; H,
6.41; N, 2.32.
1H), 4.23 (m, 1H), 4.27 (t, J ) 2.4 Hz, 1H), 4.36 (s, 1H), 4.39 (m,
1H), 4.85 (m, 1H), 7.29-7.37 (m, 10H). 31P NMR (161.92 MHz,
CDCl3): δ -17.32. MS: m/z (relative intensity) 500 (M+, 33), 485
(23), 226 (24), 149 (28), 84 (37), 56 (100), 43 (46), 41 (70). IR (KBr):
2951, 1716, 1447, 1249, 1159, 836, 743, 697, 502. Anal. Calcd for
C27H29O2PSiFe: C, 64.80; H, 5.84. Found: C, 65.01; H, 6.04.
1-Diphenylphosphino-1′-(methoxycarbonyl)-2′(Rp)-(trimethyl-
silyl)-ferrocene, (Rp)-18. Prepared from (R,Rp)-17 in 92% yield as an
1
orange solid. Mp: 109-110 °C. [R]20 ) -58° (c 0.18, CHCl3). H
D
NMR: δ 0.27 (s, 9H), 3.76 (s, 3H), 4.14 (s, 1H), 4.19 (s, 1H), 4.23
(m, 1H), 4.27 (t, J ) 2.3 Hz, 1H), 4.36 (s, 1H), 4.39 (m, 1H), 4.85 (m,
1H), 7.29-7.37 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -17.26.
MS: m/z (relative intensity) 500 (M+, 100), 485 (45), 321 (8), 305 (11),
226 (16). IR (KBr): 2948, 1708, 1583, 1444, 1340, 1248, 1158, 842.
Anal. Calcd for C27H29O2PSiFe: C, 64.80; H, 5.84. Found: C, 64.60;
H, 6.08.
1-Diphenylphosphino-1′-[N-(2-hydroxyethyl)amido]-2′(Sp)-(tri-
methylsilyl)-ferrocene, (Sp)-19. A mixture of (Sp)-18 (100 mg, 0.2
mmol), 2 mL of 2-aminoethanol, and a small amount of sodium was
heated at 100 °C for 1 h. The mixture was diluted with dichloromethane
and neutralized with acetic acid. The neutralized solution was washed
with water and then with brine and dried over Na2SO4. After removal
of the solvent, the residue was purified by silica gel column chroma-
tography with ethyl acetate:petroleum (1:2) as eluent to afford amide
1-Diphenylphosphino-1′-[N-(1,1-dimethyl-2-hydroxyethyl)amido]-
2′(Rp)-(trimethylsilyl)-ferrocene, (Rp)-21. Prepared from (Rp)-18 in
69% yield as a yellow solid (125 mg, 66%). Mp: 68-70 °C. [R]20
)
D
1
116.0° (c 0.72, CHCl3). H NMR: δ 0.28 (s, 9H), 1.39 (s, 6H), 3.64
(m, 2H), 3.97 (m, 1H), 4.09 (m, 1H), 4.17-4.18 (m, 2H), 4.33 (m,
1H), 4.44-4.45 (m, 2H), 5.26 (t, J ) 6.2 Hz, 1H), 6.44 (br, 1H), 7.24-
7.44 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -17.32. MS: m/z
(relative intensity) 557 (M+, 26), 511 (31), 484 (100), 468 (17), 452
(11), 321 (15). IR (KBr): 3335, 2955, 1739, 1663, 1642, 1516, 1244,
1161, 835. HRMS: calcd for C30H36 NO2PSiFe 557.16020, found
557.16357.
(Sp)-19 as a yellow solid (68 mg, 68%). Mp: 52-53 °C. [R]20
)
D
1
-138° (c 0.175, CHCl3). H NMR: δ 0.29 (s, 9H), 2.91 (t, J ) 5.2
Hz, 1H), 3.36 (m, 1H), 3.57-3.83 (m, 3H), 4.03 (m, 1H), 4.14 (m,
1H), 4.20 (m, 1H), 4.23 (t, J ) 2.5 Hz, 1H), 4.36 (m, 1H), 4.49-4.52
(m, 2H), 6.53 (br, 1H), 7.32-7.49 (m, 10H). 31P NMR (161.92 MHz,
CDCl3): δ -16.76. MS: m/z (relative intensity) 529 (M+, 7), 514 (7),
484 (8), 86 (67), 84 (100), 47 (28). IR (KBr): 3354, 2961, 1649, 1526,
1262, 1091, 1027, 833, 804, 742, 697. Anal. Calcd for C28H32 NO2-
PSiFe: C, 63.52; H, 6.09; N, 2.65. Found: C, 63.18; H, 5.94; N, 2.72.
1-Diphenylphosphino-1′- [N-(2-hydroxyethyl)amido]-2′(Rp)-(tri-
methylsilyl)-ferrocene, (Rp)-19. Prepared from (Rp)-18 in 70% yield
as a yellow solid. Mp: 51-52 °C. [R]20D ) 141° (c 0.55, CHCl3). 1H
NMR: δ 0.29 (s, 9H), 2.97 (br, 1H), 3.33-3.39 (m, 1H), 3.60-3.68
(m, 1H), 3.71-3.82 (m, 2H), 4.03 (s, 1H), 4.13 (s, 1H), 4.21 (m, 1H),
1-Diphenylphosphino-1′-(4,4-dimethyl-2,5-oxazolinyl]-2′(Sp)-(tri-
methylsilyl)-ferrocene, (Sp)-22. To a solution of amide (Sp)-21 (100
mg, 0.18 mmol) and 0.14 mL (0.9 mmol) of triethylamine in 2 mL of
dichloromethane was added methanesulfonyl chloride (0.014 mL, 0.18
mmol) at 0 °C. After being stirred at room temperature for 5 h, the
reaction solution was washed with chilled water (10 mL) and then with
brine, dried over Na2SO4, and concentrated under reduced pressure to
provide a residue which was purified by column chromatography with
ethyl acetate:petroleum (1:10) as an eluent to afford oxazoline (Sp)-22
as a yellow solid (75 mg, 77%). Mp: 112-113 °C. [R]20 ) 179° (c
D

6518 J. Am. Chem. Soc., Vol. 123, No. 27, 2001
Deng et al.
0.20, CHCl3). 1H NMR: δ 0.25 (s, 9H), 1.31 (d, J ) 4.5 Hz, 6H), 3.94
(d, J ) 7.9 Hz, 1H), 3.96 (d, J ) 7.9 Hz, 1H), 4.12-4.19 (m, 4H),
4.31 (d, J ) 1.1 Hz, 1H), 4.36 (m, 1H), 4.81 (dd, J ) 1.3, 2.2 Hz, 1H),
7.26-7.37 (m, 10H). 31P NMR (161.92 MHz, CDCl3): δ -17.17. MS:
m/z (relative intensity) 539 (M+, 100), 524 (16), 468 (10), 452 (33),
339 (9), 305 (9), 171 (15). IR (KBr): 2961, 1661, 1434, 1240, 1132,
837, 749, 695, 517. Anal. Calcd for C30H34NOPSiFe: C, 66.79; H,
6.35; N, 2.60. Found: C, 66.66; H, 6.23; N, 2.51.
4.00 (m, 1H), 4.50 (t, J ) 9.2 Hz, 1H), 4.72-4.96 (m, 6H), 5.05 (m,
1H), 6.36 (m, 1H), 7.34-7.89 (m, 10H).
31P NMR (161.9 MHz): δ 16.82 (major), 14.47 (minor).
Complexation Behavior of 9 with Dichlorobis(acetonitrile)-
palladium(II). A mixture of 9 (11.2 mg, 0.02 mmol) and dichlorobis-
(acetonitrile)palladium(II) (5.2 mg, 0.02 mmol) was dissolved in
acetonitrile-d3 (0.5 mL). The resulting solution gave two sets of signals
1
in the H NMR spectrum and presented a ratio of 42:58 in the 31P
1-Diphenylphosphino-1′-(4,4-dimethyl-2,5-oxazolinyl]-2′(Rp)-(tri-
methylsilyl)-ferrocene, (Rp)-22. Prepared from (Rp)-21 in 75% yield
as a yellow solid. Mp: 110-112 °C. [R]20D ) -180.0° (c 0.58, CHCl3).
1H NMR: δ 0.25 (s, 9H), 1.31 (d, J ) 5.2 Hz, 6H), 3.94 (d, J ) 7.9
Hz, 1H), 3.96 (d, J ) 7.9 Hz, 1H), 4.13-4.19 (m, 4H), 4.31 (s, 1H),
4.37 (s, 1H), 4.82 (s, 1H), 7.26-7.37 (m, 10H). 31P NMR (161.92 MHz,
CDCl3): δ -17.30. MS: m/z (relative intensity) 539 (M+, 93), 524
(14), 452 (22), 339 (4), 57 (100). IR (KBr): 2959, 1644, 1430, 1255,
1128, 982, 757, 702. HRMS: calcd for C30H34NOPSiFe 539.14964,
found 539.14869.
NMR spectrum at room temperature, which might be assigned as
diastereomers 28 and 27, respectively.
27 (Major). 1H NMR (400 MHz): δ 0.20 (s, 9H), 0.67 (d, J ) 6.6
Hz, 3H), 0.91 (d, J ) 7.1 Hz, 3H), 2.73 (m, 1H), 3.53 (m, 1H), 3.78
(t, J ) 9.3 Hz, 1H), 4.24 (dd, J ) 5.2, 9.3 Hz, 1H), 4.52-4.60 (m,
2H), 4.76 (m, 1H), 4.86 (m, 1H), 4.95 (m, 1H), 5.07 (t, J ) 2.4 Hz,
1H), 7.10 (s, 1H), 7.24-7.80 (m, 10H).
28 (Minor). 1H NMR (400 MHz): δ 0.20 (s, 9H), 1.00 (d, J ) 5.6
Hz, 3H), 1.01 (d, J ) 5.6 Hz, 3H), 2.91 (m, 1H), 4.35 (t, J ) 7.3 Hz,
1H), 4.48-4.60 (m, 4H) 4.63 (m, 1H), 4.76 (m, 1H), 5.61 (br, 2H),
5.81 (s, 1H), 7.24-7.80 (m, 10H).
General Procedure for Palladium-Catalyzed Allylic Alkylation.
A mixture of ligand 9 (11.6 mg, 0.02 mmol) and [Pd(η3-C3H5)Cl]2 (3.7
mg, 0.01 mmol) in dry dichloromethane (4 mL) was stirred at room
temperature for 1 h, and to the resulting yellow solution were added
potassium acetate (2.0 mg 0.02 mmol) and 23 (100 mg, 0.4 mmol).
After an additional 10 min of stirring, to the resulting solution were
added dimethyl malonate (0.12 mL, 1.2 mmol) and BSA (0.3 mL, 1.2
mmol). The reaction was carried out at room temperature and monitored
by TLC for the disappearance of 23. When all of the 23 had been
converted to the product, the reaction mixture was diluted with ether,
washed with saturated aqueous NH4Cl solution, and then dried over
Na2SO4. After removal of the solvent, the residue was purified by
preparative TLC with ethyl acetate:petroleum (1:10) as eluent to afford
31P NMR (161.9 MHz): δ 17.17 (major), 18.29 (minor).
Complexation Behavior of 16 with Dichlorobis(acetonitrile)-
palladium(II). A mixture of 16 (11.2 mg, 0.02 mmol) and dichlorobis-
(acetonitrile)palladium(II) (5.2 mg, 0.02 mmol) was dissolved in
acetonitrile-d3 (0.5 mL). The resulting solution gave two sets of signals
in the 1H NMR spectrum and presented a ratio of 22:1 in the 31P NMR
spectrum at room temperature, which might be assigned as diastereo-
mers 30 and 29, respectively.
30 (Major). 1H NMR (400 MHz): δ 0.27 (s, 9H), 0.44 (d, J ) 6.8
Hz, 3H), 1.13 (d, J ) 6.9 Hz, 3H), 2.10 (m, 1H), 3.92 (s, 1H), 4.06
(m, 1H), 4.09 (dd, J ) 8.7, 12.2 Hz, 1H), 4.46 (m, 1H), 4.50 (m, 1H),
4.58 (dd, J ) 8.7, 10.1 Hz, 1H), 4.68 (m, 1H), 4.83 (m, 1H), 5.03 (t,
J ) 2.5 Hz, 1H), 7.13 (s, 1H), 7.27-7.88 (m, 10H).
1
pure 24. H NMR (400 MHz, CDCl3): δ 3.52 (s, 3H), 3.70 (s, 3H),
31P NMR (161.9 MHz): δ 15.75 (major), 18.51 (minor).
3.95 (d, J ) 10.8 Hz, 1H), 4.27 (dd, J ) 8.8, 10.8 Hz, 1 H), 6.30 (dd,
J ) 8.8, 15.8 Hz, 1 H), 6.44 (d, J ) 15.8 Hz, 1 H), 7.19-7.34 (m,
10H). The enantiomeric excess was determined by HPLC analysis
(Chiralcel OD, hexane:2-propanol (80:20); flow rate ) 0.7 mL/min; tR
) 18.7 min, tS ) 20.4 min). The absolute configuration of the product
was assigned by comparing the sign of its specific rotation with
literature data.26
[Pd(η3-PhCHCHCHPh)(8a)][SbF6] (8aa). To a solution of ligand
8a (96 mg, 0.2 mmol) in dichloromethane (20 mL) was added [Pd-
(η3-PhCHCHCHPh)(µ-Cl)]2 (69 mg, 0.1 mmol). After the solution
turned clear again, AgSbF6 (69 mg, 0.2 mmol) was added and stirring
continued for 2 h at room temperature. The suspension was filtered
over Celite, and the solvent was evaporated in vacuo, to afford a yellow
foamy solid. The resulting solid was recrystallized from dichloro-
methane/ethyl ether, yielding 183 mg (90%) of complex 8aa as a yellow
amorphous solid.
General Procedure for Palladium-Catalyzed Allylic Amination.
A mixture of ligand 14 (9.9 mg, 0.02 mmol) and [Pd(η3-C3H5)Cl]2 (3.7
mg, 0.01 mmol) in dry 1,2-dichloroethane (4 mL) was stirred at room
temperature for 1 h, and to the resulting yellow solution was added 23
(100 mg, 0.4 mmol). After an additional 10 min of stirring, to the
resulting solution was added benzylamine (0.1 mL, 0.8 mmol). The
reaction was carried out at room temperature and monitored by TLC
for the disappearance of 23. When all of the 23 had been converted to
the product, the reaction mixture was diluted with ether, washed with
saturated aqueous NH4Cl solution, and then dried over Na2SO4. After
removal of the solvent, the residue was purified by preparative TLC
with ethyl acetate:petroleum (1:10) as eluent to afford pure product
8aa (Major). 1H NMR (400 MHz, CD2Cl2): δ 0.52 (d, J ) 6.7 Hz,
3H), 0.73 (d, J ) 6.7 Hz, 3H), 1.76 (m, 1H), 2.21 (m, 1H), 3.73 (d, J
) 1.1 Hz, 1H), 3.77 (s, 1H), 3.88 (d, J ) 10.6 Hz, 2H), 4.29 (d, J )
0.9 Hz, 1H), 4.51-4.60 (m, 2H), 4.77 (t, J ) 1.2 Hz, 1H), 4.87 (d, J
) 1.1 Hz, 1H), 4.97 (d, J ) 1.2 Hz, 1H), 5.95 (dd, J ) 13.4, 8.5 Hz
(JP-H), 1H), 6.12 (s, 1H), 6.84 (dd, J ) 13.3, 11.5 Hz, 1H), 6.75-7.04
(m, 6H), 7.10-7.71 (m, 14H). 31P NMR (161.9 MHz): δ 14.79. 13C
NMR (100.58 MHz): δ 73.9 (allyl trans to N), 109.0 (central allyl),
102.0 (allyl trans to P). IR (cm-1): 1626, 695, 658, 507. ESI: m/z 780
(M+ - SbF6). Anal. Calcd for C43H41NF6OPFePdSb: C, 50.80; H, 4.06;
N, 1.38. Found: C, 50.41; H, 3.79; N, 1.39.
1
29. H NMR (300 MHz, CDCl3): δ 3.75-3.81 (AB, J ) 13.3 Hz, 2
H), 4.39 (d, J ) 7.4 Hz, 1 H), 6.31 (dd, J ) 7.4, 15.9 Hz, 1 H), 6.58
(d, J ) 15.9 Hz, 1 H), 7.17-7.45 (m, 15H). The enantiomeric excess
was determined by HPLC analysis (Chiralcel OJ, flow rate ) 0.6 mL/
min, n-hexane:i-PrOH ) 87:13, tS ) 20.3 min, tR ) 24.3 min). The
absolute configuration of the product was assigned by comparing the
sign of its specific rotation with literature data.22a
[Pd(η3-PhCHCHCHPh)(9)][SbF6] (9a). To a solution of ligand 9
(110 mg, 0.2 mmol) in dichloromethane (20 mL) was added [Pd(η3-
PhCHCHCHPh)(µ-Cl)]2 (69 mg, 0.1 mmol). After the solution turned
clear again, AgSbF6 (69 mg, 0.2 mmol) was added and stirring
continued for 2 h at room temperature. The suspension was filtered
over Celite, and the solvent was evaporated in vacuo, to afford a yellow
foamy solid. The resulting solid was recrystallized from dichloro-
methane/ethyl ether and yielded 187 mg (86%) of complex 9a as a
yellow amorphous solid.
Complexation Behavior of 8a with Dichlorobis(acetonitrile)-
palladium(II). A mixture of 8a (9.7 mg, 0.02 mmol) and dichlorobis-
(acetonitrile)palladium(II) (5.2 mg, 0.02 mmol) was dissolved in
acetonitrile-d3 (0.5 mL). The resulting solution gave two sets of signals
1
in the H NMR spectrum and presented a ratio of 62:38 in the 31P
1
9a (Major). H NMR (400 MHz, CD2Cl2): δ 0.17 (d, J ) 6.7 Hz,
NMR spectrum at room temperature, which might be assigned as
diastereomers 26 and 25, respectively.
3H), 0.2 (s, 9H), 0.87 (m, 1H), 1.21 (d, J ) 6.7 Hz, 2H), 3.61-3.77
(m, 3H), 4.15 (m, 1H), 4.35 (m, 1H), 4.49 (m, 1H), 4.32-4.43 (m,
3H), 4.69 (s, 1H), 5.23 (s, 1H), 6.35 (dd, J ) 13.9, 8.7 (JP-H) Hz, 1H),
6.44 (br, 1H), 6.65 (t, 12.8 Hz, 1H), 6.75-7.85 (m, 20H). 31P NMR
(161.9 MHz): δ 18.24. 13C NMR (100.58 MHz): δ 72.1 (allyl trans
to N), 113.7 (central allyl), 110.8 (allyl trans to P).
26 (Major). 1H NMR (400 MHz): δ 0.64 (d, J ) 6.7 Hz, 3H), 0.83
(d, J ) 6.7 Hz, 3H), 2.86 (m, 1H), 3.22 (t, J ) 9.2 Hz, 1H), 3.96 (dd,
J ) 6.8, 9.2 Hz, 1H), 4.46 (s, 1H), 4.72-4.96 (m, 5H), 5.10 (s, 1H),
5.81 (s, 1H), 6.48 (m, 1H), 7.34-7.89 (m, 10H).
25 (Minor). 1H NMR (400 MHz): δ 0.44 (d, J ) 6.2 Hz, 3H), 1.67
(d, J ) 6.2 Hz, 3H), 2.50 (m, 1H), 3.66 (dd, J ) 9.2, 12.2 Hz, 1H),
9a (Minor). H NMR (400 MHz, CD2Cl2): δ -0.22 (d, J ) 6.7
1
Hz, 3H), 0.03 (s, 9H), 0.85 (d, J ) 6.7 Hz, 3H), 1.80 (m, 1H), 3.61-

Role of Planar Chirality in Asymmetric Reactions
J. Am. Chem. Soc., Vol. 123, No. 27, 2001 6519
3.77 (m, 1H), 4.17 (s, 1H), 4.30-4.42 (m, 3H), 4.46 (s, 1H), 4.52 (s,
1H), 4.58-4.62 (m, 2H), 5.00 (t, J ) 2.5 Hz, 1H), 5.74 (s, 1H), 6.10
(dd, J ) 13.4, 8.7 (JP-H) Hz, 1H), 6.65 (t, 12.8 Hz, 1H), 6.75-7.85
(m, 20H). 31P NMR (161.9 MHz): δ 16.34. 13C NMR (100.58 MHz):
δ 71.7 (allyl trans to N), 110.6 (central allyl), 103.2 (allyl trans to P).
31P NMR (161.9 MHz): δ 15.54 (the isomer of 5%). IR (cm-1): 2959,
1616, 1437, 1249, 836, 695, 658. ESI: m/z 852 (M+ - SbF6). Anal.
Calcd for C46H49NF6OSiPFePdSb: C, 50.74; H, 4.54; N, 1.29. Found:
C, 51.23; H, 4.68; N, 1.23.
over Celite, and the solvent was evaporated in vacuo, to afford a yellow
foamy solid. The resulting solid was recrystallized from dichloro-
methane/ethyl ether and yielded 181 mg (88%) of complex 8ca as a
yellow amorphous solid.
8ca (Major). 1H NMR (400 MHz, CD2Cl2): δ 0.76 (s, 9H), 2.01 (t,
J ) 11.1 Hz, 1H), 3.74 (s, 1H), 3.82-3.95 (m, 2H), 4.32 (m, 2H),
4.53 (d, J ) 10.9 Hz, 1H), 4.57 (m, 1H), 4.80 (m, 1H), 4.88 (m, 1H),
4.99 (m, 1H), 6.15 (dd, J ) 13.6, 7.8 (JP-H) Hz, 1H), 6.23 (m, 1H),
6.63-6.73 (m, 5H), 6.75 (dd, J ) 13.6, 11.0 Hz, 1H), 7.05 (t, J ) 7.8
Hz, 2H), 7.10-7.31 (m, 3H), 7.34-7.69 (m, 10H). 31P NMR (161.9
MHz): δ 13.24 (major), 18.77 (minor). 13C NMR (100.58 MHz): δ
71.9 (allyl trans to N), 108.7 (central allyl), 103.6 (allyl trans to P). IR
[Pd(η3-PhCHCHCHPh)(14)][SbF6] (14a). To a solution of ligand
14 (99 mg, 0.2 mmol) in dichloromethane (20 mL) was added [Pd-
(η3-PhCHCHCHPh)(µ-Cl)]2 (69 mg, 0.1 mmol). After the solution
turned clear again, AgSbF6 (69 mg, 0.2 mmol) was added and stirring
continued for 2 h at room temperature. The suspension was filtered
over Celite, and the solvent was evaporated in vacuo, to afford a yellow
foamy solid. The resulting solid was recrystallized from dichloro-
methane/ethyl ether and yielded 177 mg (86%) of complex 14a as a
yellow amorphous solid.
(cm-1): 1623, 1484, 1146, 760, 695, 658, 509. ESI: m/z 794 (M+
-
SbF6). Anal. Calcd for C44H43NF6OPFePdSb: C, 51.27; H, 4.20; N,
1.36. Found: C, 51.11; H, 4.06; N, 1.35.
Acknowledgment. Financial support from the Major Basic
Research Development Program (grant No. G2000077506), the
National Natural Science Foundation of China, Chinese Acad-
emy of Sciences, National Outstanding Youth Fund, and
Shanghai Committee of Science and Technology is acknowl-
edged. We thank Prof. Henry N. C. Wong and Drs. Tze-Lock
Chan and Yong Tang for their helpful and inspiring discussions.
1
14 (Major). H NMR (400 MHz, CD2Cl2): δ 0.56 (d, J ) 4.8 Hz,
3H), 0.74 (d, J ) 4.8 Hz, 3H), 1.81 (m, 1H), 2.20 (s, 3H), 2.26 (td, J
) 5.6, 10.3 Hz, 1H), 3.73 (s, 1H), 3.76-3.93 (m, 3H), 4.32 (m, 1H),
4.38 (m, 1H), 4.46 (s, 1H), 4.49 (d, J ) 11.1 Hz, 1H), 4.85 (t, J ) 2.6
Hz, 1H), 6.02 (dd, J ) 13.6, 8.6 (JP-H) Hz, 1H), 6.05 (s, 1H), 6.70-
7.71 (m, 21H). 13C NMR (100.58 MHz): δ 73.4 (allyl trans to N),
108.7 (central allyl), 102.6 (allyl trans to P). 31P NMR (161.9 MHz):
δ 15.33 (major), 19.25 (minor). IR (cm-1): 1624, 1482, 1146, 760,
695, 658, 507. ESI: m/z 794 (M+ - SbF6). Anal. Calcd for C44H43-
NF6OPFePdSb: C, 51.27; H, 4.20; N, 1.36. Found: C, 51.43; H, 3.89;
N, 1.39.
Supporting Information Available: Full spectral charac-
terization for all new ferrocene compounds and Pd complexes,
and crystallographic data of two Pd complexes (PDF). X-ray
crystallographic data, in CIF format, are also available. This
material is available free of charge via the Internet at
http://pubs.acs.org.
[Pd(η3-PhCHCHCHPh)(8)][SbF6] (8ca). To a solution of ligand
8c (99 mg, 0.2 mmol) in dichloromethane (20 mL) was added [Pd(η3-
PhCHCHCHPh)(µ-Cl)]2 (69 mg, 0.1 mmol). After the solution turned
clear again, AgSbF6 (69 mg, 0.2 mmol) was added and stirring
continued for 2 h at room temperature. The suspension was filtered
JA002657Q