New P,N-ferrocenyl ligands for rhodium-catalyzed hydroboration and palladium-catalyzed allylic alkylation

Article abstract of DOI:10.1016/S0957-4166(02)00827-3

A set of nine new chiral P,N-ferrocenyl ligands for metal-catalyzed enantioselective reactions has been prepared. The rhodium-catalyzed hydroboration of styrene with catechol borane proceeded with high regioselectivity (up to 97:3) or with high enantioselectivity (up to 92% ee) depending on the catalyst. Good results were also obtained in the palladium-catalyzed asymmetric alkylation of 1,3-diphenylallylic systems (up to 94% ee).

Full text of DOI:10.1016/S0957-4166(02)00827-3

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 14 (2003) 255–264
New P,N-ferrocenyl ligands for rhodium-catalyzed hydroboration
and palladium-catalyzed allylic alkylation
Ralf J. Kloetzing, Matthias Lotz and Paul Knochel*
Department of Chemistry of Ludwig-Maximilians-University, Butenandtstraße 5-13, 81377 Munich, Germany
Received 28 October 2002; accepted 3 December 2002
Abstract—A set of nine new chiral P,N-ferrocenyl ligands for metal-catalyzed enantioselective reactions has been prepared. The
rhodium-catalyzed hydroboration of styrene with catechol borane proceeded with high regioselectivity (up to 97:3) or with high
enantioselectivity (up to 92% ee) depending on the catalyst. Good results were also obtained in the palladium-catalyzed
asymmetric alkylation of 1,3-diphenylallylic systems (up to 94% ee). © 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction
methanol in the presence of acetic acid with complete
retention of configuration.6 After recrystallization from
methanol, the enantiomerically pure ethers 5a–c were
obtained (Scheme 1). These are key intermediates, as
the methoxy group allows directed ortho-lithiation of
the functionalized cyclopentadienyl ring with very high
diastereoselectivity (>96% de).7 Furthermore, the
methoxy function also serves as a leaving group in
nucleophilic substitution reactions in acidic media
which also proceed with complete retention of
configuration.
Chiral ligands incorporating both planar and central
chirality have found widespread application in asym-
metric catalysis.1 Among these, the ferrocene frame-
work is unparalleled in its versatility.2 Recently, we
reported the synthesis of new P,N-ferrocenyl ligands
via a methoxy directed ortho-lithiation.3
2. Results and discussion
2.1. Synthesis of the P,N-ligands
Next, the methyl ethers 5a–c were metalated with tert-
butyllithium and transmetalated to the corresponding
zinc compounds, which were submitted to a palla-
dium(0)-catalyzed cross-coupling reaction (Negishi-cou-
pling) with various aryl iodides.8 We have already
reported the use of 2-iodopyrimidine and 2-iodopy-
ridine for such cross-couplings.3 Herein, we report an
extension of the scope of the reaction to 2-iodoquino-
The key intermediates 5a–c were readily accessible by
acylation of ferrocene 1 with acid chlorides 2a–c.4 The
resulting ferrocenyl ketones 3a–c underwent a smooth
CBS-reduction providing the ferrocenyl alcohols 4a–c
with high enantioselectivity.5 These were converted into
the corresponding methyl ethers 5a–c by treatment with
Scheme 1. Preparation of chiral (ferrocenyl)benzylic methyl ethers 5a–c.
* Corresponding author. Tel.: +49 (0)89 2180 7681; fax: +49 (0)89 2180 7680; e-mail: paul.knochel@cup.uni-muenchen.de
0957-4166/03/$ - see front matter © 2003 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(02)00827-3

256
R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
The Rh-catalyzed addition of catecholborane to styrene
(Scheme 4) afforded the alcohols 9 and 10 after oxida-
tion with hydrogen peroxide. In preliminary studies, we
varied the reaction conditions to minimize the amount
of linear alcohol 10 formed and to maximize conversion
of the reaction and enantiomeric excess of the branched
alcohol 9 (Table 3). Entries 1 and 2 show that the use
of 2 mol% ligand compared to 1.1 mol% led to
improved regio- and stereoselectivity, but lower conver-
sion. The hydroboration reaction using ligand 7a dis-
played high temperature dependence. At −35°C (entry
3), this reaction was less stereoselective, while the con-
version was not increased. Ligand 7d behaved differ-
ently, suggesting that ligand 7a decomposed more
readily. We have now tested all other ligands at −45°C,
using 2 mol% ligand (Table 4). The results can be
clearly divided into three groups. The ligands 7a–c
(entries 1–3), bearing the pyrimidyl moiety, showed
good regioselectivity, while conversion and enantiose-
lectivity were only moderate, whereas ligands 7g–i
(entries 7–9) with the quinolyl moiety gave high conver-
sion and good enantioselectivity, along with low
regioselectivity. The ligands 7d and 7e (entries 4 and 5)
occupy a medium position, while ligands 7f (entry 6)
gave only poor results. In conclusion, 7g was the best
ligand (92% ee with full conversion), although the
regioselectivity was only modest.
line (Scheme 2 and Table 1) and the preparation of nine
new ligands.
Scheme 2. ortho-Metalation of the methyl ethers 5a–c,
transmetalation and cross-coupling reaction.
The cross-coupling products 6a–i underwent a nucleo-
philic substitution reaction with diphenylphosphine.
The resulting P,N-ligands 7a–i were converted in situ
into their borane complexes 8a–i which could be han-
dled easily in air and purified by conventional column
chromatography (Scheme 3 and Table 2).9 For use in
asymmetric catalysis, the ligands were freshly depro-
tected by repeated treatment with diethylamine.10
Table 1. Yields of the cross-coupling reactions
Ar%
Ar=Phenyl
Ar=o-Tolyl
Ar=3,5-Xylyl
(%)
(%)
(%)
2-Pyrimidyl
2-Pyridyl
2-Quinolyl
6a: 74
6d: 60
6g: 68
6b: 84
6e: 73
6h: 83
6c: 85
6f: 83
6i: 78
Scheme 4. Rhodium-catalyzed hydroboration of styrene.
The Pd-catalyzed allylation of dimethyl malonate with
the 1,3-diphenylallyl system (Scheme 5) was carried out
with ligand 7a between 22°C and 0°C. Ligand 7a
induced very high enantioselectivity at 0°C, but the
conversion was low (Table 5, entry 2). All other ligands
were tested at 22°C (Table 5). The enantioselectivity
decreased with increasing steric bulk of the substituent
on the a-carbon (7a–c and 7g–i entries 1, 3, 4 and
8–10), with pyrimidyl or quinolyl as the N-donor. With
pyridyl as N-donor, the situation is changed and the
enantioselectivty increases with the steric hindrance
(7d–f, entries 5–7). In conclusion, the best results were
obtained with ligand 7f (94% ee, 88% isolated yield).
Scheme 3. Phosphination and protection of the ligands as
borane complexes.
Table 2. Isolated yields of the protected ligands
Ar%
Ar=Phenyl
Ar=o-Tolyl
Ar=3,5-Xylyl
(%)
(%)
(%)
2-Pyrimidyl
2-Pyridyl
2-Quinolyl
8a: 54
8d: 91
8g: 31
8b: 29
8e: 99
8h: 76
8c: 17
8f: 88
8i: 33
3. Conclusion
We have prepared a range of nine P,N-ferrocenyl lig-
ands and showed their utility in the Rh-catalyzed
hydroboration and the Pd-catalyzed allylic alkylation.
The results of this study show that fine-tuning of the
ligands has a significant influence on their performance.
2.2. Asymmetric catalysis
We examined the scope of these compounds as ligands
in Pd-catalyzed asymmetric allylic alkylation11 and in
Rh-catalyzed asymmetric hydroboration.12a–f

R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
257
Table 3. Rhodium-catalyzed hydroboration of styrene: optimization of reaction conditions
Entry
Ligand
Temperature
Reaction time
(h)
Conversionb
(%)
Enantioselectivitya
(% ee)
Regioselectivityb (branched:linear)
(°C)
1
2
3
4
5
7a (1.1 mol%)
7a (2 mol%)
7a (2 mol%)
7d (2 mol%)
7d (2 mol%)
−45
−45
−35
−45
−35
19
19
39
16
39
86
74
71
75
77
41
57
25
61
62
92:8
97:3
65:35
87:13
85:15
a The enantiomeric excess was determined by HPLC (column: Chiracel OD-H). The absolute configuration was established by comparison with
literature data.
b The ratio of isomers and conversion was determined by GC.
Table 4. Rhodium-catalyzed hydroboration of styrene
Entry
Liganda
Reaction time (h)
Conversion (%)
Enantioselectivityb (% ee)
Regioselectivityc (branched:linear)
1
2
3
4
5
6
7
8
9
7a
7b
7c
7d
7e
7f
7g
7h
7i
19
16
16
16
14
14
16
16
16
74
52
53
75
54
22
\99
92
57
55
59
61
80
32
92
82
86
97:3
87:13
90:10
87:13
84:16
57:43
64:36
68:32
65:35
\99
a Reaction conditions: 2 mol% ligand, −45°C
b The enantiomeric excess was determined by HPLC (column: Chiracel OD-H). The absolute configuration was established by comparison with
literature data.
c The ratio of isomers was determined by GC.
4. Experimental
All reactions were carried out under argon using stan-
dard Schlenk techniques. 1H and 13C NMR spectra
were recorded on a Bruker AMX 300 instrument. 31P
NMR spectra were recorded on a Varian Mercury 200
instrument. Chemical shifts (l) are given as ppm rela-
tive to the residual solvent peak. IR spectra were
recorded on a Perkin–Elmer 1420 IR spectrometer.
Mass spectra were recorded on a Finnnigan MAT 95 Q
spectrometer. Optical rotations were measured on a
Perkin–Elmer 241 polarimeter. Column chromatogra-
phy was performed on Merck silica gel 60 (230–400
mesh ASTM). Thin-layer chromatography was per-
formed on Merck TLC-plates silica gel 60 F-254. Enan-
tiomeric excesses were determined by HPLC. Chiralcel
OD-H and OD (Daicel Chemical Industries) colums
were used with n-heptane/i-propanol as a mobile phase
and detection by a diode array UV–vis detector at 214
nm.
Scheme 5. Palladium-catalyzed allylic alkylation.
Table 5. Palladium-catalyzed allylic alkylation
Entry
Liganda
Yieldc (%)
Enantioselectivityd (% ee)
1
7a
7a
7b
7c
7d
7e
7f
7g
7h
7i
94
21
92
58
59
73
88
76
76
93
92
\99
86
89
87
93
94
91
85
2b
3
4
5
6
7
8
9
10
4.1. Acylation of ferrocene
4.1.1. Benzoylferrocene, 3a. Aluminium(III) chloride
(7.33 g, 55.0 mmol) was added to a solution of benzoyl
chloride (2a) (6.38 mL, 7.72 g, 55.0 mmol) in
dichloromethane (40 mL) at 0°C. This solution was
added to a suspension of ferrocene (1) (9.30 g, 50.0
mmol) in dichloromethane (100 mL) at 0°C over 30
min. The reaction mixture was stirred at rt and after 1.5
h, the mixture was cooled again to 0°C and was care-
56
a Reaction conditions: temperature 22°C, reaction time 20 h.
b Temperature 0°C.
c Isolated yield after purification by column chromatography.
d The enantiomeric excess was determined by HPLC (column:
Chiracel OD-H). The absolute configuration was established by
comparison with literature data.

258
R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
fully hydrolyzed (CAUTION: gas evolution). The mix-
ture was neutralized with satd NaHCO3 solution and
extracted with dichloromethane (300 mL). The organic
layers were washed with satd NaHCO3 solution, water
and brine and dried over MgSO4. The crude material
was purified by column chromatography (n-pentane/
diethyl ether 6:1). Benzoylferrocene 3a was obtained as
a red solid (10.34 g, 35.6 mmol, 71%); mp 106°C; IR
(KBr): v˜ 3092 (w), 1627 (s), 1376 (m), 1289 (s), 1058
CAUTION: gas evolution) was added dropwise. The
reaction mixture was hydrolyzed with satd NH4Cl
solution and extracted with diethyl ether (150 mL).
The organic layers were washed with water and brine
and dried over MgSO4. The crude product was
purified by column chromatography (n-pentane/diethyl
ether 4:1). Alcohol 4a was isolated as a red solid (4.87
g, 16.7 mmol, 94%, 98% ee (R)). HPLC analysis (OD-
H, 92% n-heptane, 8% i-propanol, 0.6 mL/min): reten-
tion time (min) 21.1 (R), 33.3 (S); mp 89°C;
[h]D=−103.0 (c 0.92, CHCl3); IR (KBr): v˜ 3082 (m),
1494 (m), 1453 (m), 1236 (m), 1182 (m), 1104 (m),
1048 (m), 1017 (m), 1000 (m), 815 (m), 720 (m), 700
1
(m), 724 (s); H NMR (CDCl3): l 7.92–7.87 (m, 2H),
7.57–7.44 (m, 3H), 4.91 (dd, J=1.8 Hz, 2H), 4.58 (dd,
J=1.8 Hz, 2H), 4.21 (s, 5H); 13C NMR (CDCl3): l
199.1, 139.8, 131.4 (CH), 128.2 (CH), 128.0 (CH),
78.1, 72.5 (CH), 71.5 (CH), 70.2 (CH); MS (EI, 70 eV)
m/z (%): 290 (M+, 100), 262 (2).
1
(s); H NMR (CDCl3): l 7.42–7.23 (m, 5H), 5.48 (d,
J=3.1 Hz, 1H), 4.23–4.19 (m, 9H), 2.47 (d, J=3.1 Hz,
1H); 13C NMR (CDCl3): l 143.2, 128.2 (CH), 127.4
(CH), 126.2 (CH), 94.2, 72.0 (CH), 68.4 (CH), 68.1
(CH), 68.1 (CH), 67.4 (CH), 66.0 (CH); MS (EI, 70
eV) m/z (%): 292 (M+, 38), 275 (81), 153 (100); HRMS
calcd for C17H16FeO: 292.0551. Observed: 292.0576.
4.1.2. (2-Methylbenzoyl)ferrocene, 3b. Prepared accord-
ing to the procedure described above from ferrocene 1
(9.30 g, 50.0 mmol), aluminium(III) chloride (7.33 g,
55.0 mmol) and 2-methylbenzoyl chloride (2b) (7.20
mL, 8.50 g, 55.0 mmol) with a reaction time of 5 h
and isolated as a red solid (12.34 g, 40.6 mmol, 81%);
mp 79°C; IR (film): v˜ 3097 (m), 1644 (s), 1444 (s),
4.2.2. (R)-(a-Hydroxy(2-methylphenyl)methyl)ferrocene,
4b. Prepared according to the procedure described
above from (2-methylbenzoyl)ferrocene (3b) (5.63 g,
18.5 mmol) with borane dimethyl sulfide complex
(2.50 mL, 2.00 g, 26.3 mmol) and CBS-catalyst (1.54
g, 5.55 mmol). 4b was isolated as a yellow solid (5.34
g, 17.4 mmol, 94%, 93% ee (R)). HPLC analysis (OD-
H, 92% n-heptane, 8% i-propanol, 0.6 mL/min): reten-
tion time (min) 15.0 (R), 16.5 (S); mp 51°C;
[h]D=−146.7 (c 1.06, CHCl3); IR (film): v˜ 3094 (m),
1488 (m), 1462 (m), 1411 (m), 1106 (s), 1043 (s), 1002
(s), 819 (s), 741 (s), 485 (s); 1H NMR (CDCl3): l
7.52–7.47 (m, 1H), 7.25–7.10 (m, 3H), 5.63 (d, J=4.0
Hz, 1H), 4.28–4.10 (m, 9H), 2.53 (d, J=4.0 Hz, 1H),
2.35 (s, 3H); 13C NMR (CDCl3): l 141.4, 135.0, 130.1
(CH), 127.2 (CH), 125.9 (CH), 125.8 (CH), 94.6, 68.7
(CH), 68.4 (CH), 68.1 (CH), 67.8 (CH), 67.4 (CH),
66.9 (CH), 19.2 (CH3); MS (EI, 70 eV) m/z (%): 306
(M+, 20), 304 (15), 290 (100); HRMS calcd for
C18H18FeO: 306.0707. Observed: 306.0715.
1
1376 (s), 1295 (s), 1277 (s), 746 (s), 484 (s); H NMR
(CDCl3): l 7.60–7.56 (m, 1H), 7.43–7.37 (m, 1H),
7.32–7.27 (m, 2H), 4.79 (dd, J=2.0 Hz, 2H), 4.60 (dd,
J=2.0 Hz, 2H), 4.29 (s, 5H), 2.45 (s, 3H); 13C NMR
(CDCl3): l 202.2, 139.9, 135.7, 130.9 (CH), 129.7
(CH), 127.4 (CH), 124.9 (CH), 79.4, 72.5 (CH), 71.2
(CH), 69.9 (CH), 19.8 (CH3); MS (EI, 70 eV) m/z (%):
304 (M+, 100), 91 (17); HRMS calcd for C18H16FeO:
304.0551. Observed: 304.0550.
4.1.3. (3,5-Dimethylbenzoyl)ferrocene, 3c. Prepared
according to the procedure described above from fer-
rocene (1) (9.30 g, 50.0 mmol), aluminium(III) chloride
(7.33 g, 55.0 mmol) and 3,5-dimethylbenzoyl chloride
(2c) (9.28 g, 55.0 mmol) with a reaction time of 22 h
and isolated as a red solid (10.71 g, 33.7 mmol, 67%);
mp 88°C; IR (KBr): v˜ 2916 (m), 1640 (s), 1446 (s),
1
1249 (s), 766 (s); H NMR (CDCl3): l 7.51–7.23 (m,
2H), 7.18 (m, 1H), 4.90 (dd, J=2.0 Hz, 2H), 4.57 (dd,
J=2.0 Hz, 2H), 4.20 (s, 5H), 2.40 (s, 6H); 13C NMR
(CDCl3): l 199.4, 139.9, 137.7, 133.1 (CH), 125.9
(CH), 78.4, 72.3 (CH), 71.5 (CH), 70.2 (CH), 21.3
(CH3); MS (EI, 70 eV) m/z (%): 318 (M+, 100), 105
(19). HRMS calcd for C19H18FeO: 318.0707.
Observed: 318.0705.
4.2.3.
(R)-(a-Hydroxy(3,5-dimethylphenyl)methyl)-
ferrocene, 4c. Prepared according to the procedure
described above from (3,5-dimethylbenzoyl)ferrocene
3c (3.28 g, 10.3 mmol) with borane dimethyl sulfide
complex (1.42 mL, 1.14 g, 15.0 mmol) and CBS-cata-
lyst (0.800 g, 2.89 mmol). 4c was isolated as a yellow
oil (2.87 g, 8.95 mmol, 87%, 97% ee (R)). HPLC
analysis (OD-H, 92% n-heptane, 8% i-propanol, 0.6
mL/min): retention time (min) 13.8 (R), 22.4 (S);
[h]D=−77.9 (c 1.25, CHCl3); IR (film): v˜ 2917 (m),
1608 (m), 1465 (m), 1412 (m), 1378 (m), 1106 (s), 1042
(s), 1022 (s), 1001 (s), 908 (s), 854 (s), 818 (s), 487 (s);
1H NMR (CDCl3): l 7.00 (s, 2H), 6.89 (s, 1H), 5.11
(d, J=3.2 Hz, 1H), 4.24–4.05 (m, 9H), 2.41 (d, J=3.2
Hz, 1H), 2.30 (s, 6H); 13C NMR (CDCl3): l 143.2,
137.7, 129.1 (CH), 124.0 (CH), 94.4, 72.1 (CH), 68.4
(CH), 68.0 (CH), 68.0 (CH), 67.5 (CH), 65.8 (CH),
21.3 (CH3); MS (EI, 70 eV) m/z (%): 320 (M+, 41),
318 (41), 304 (100), 255 (25); HRMS calcd for
C19H20FeO: 320.0864. Observed: 320.0866.
4.2. Reduction of the aryl ferrocenyl ketones 3a–c
4.2.1. (R)-(a-Hydroxyphenylmethyl)ferrocene, 4a.
A
solution of borane dimethyl sulfide complex (2.46 mL,
1.97 g, 25.9 mmol) in THF (25 mL) was prepared.
The CBS catalyst (methyl oxazaborolidine; 1.49 g, 5.36
mmol, 0.3 equiv.) was dissolved in 20% of this solu-
tion. A solution of the benzoylferrocene (3a) (5.17 g,
17.8 mmol) in THF (30 mL) and the remaining
borane dimethyl sulfide complex solution were added
simultaneously at 0°C over 20 min. The disappearance
of the red coloured ketone indicated the reaction pro-
gress. After complete reduction methanol (4 mL,

R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
259
4.3. Methylation of the alcohols 4a–c
4.29–4.25 (m, 1H), 4.14–4.10 (m, 1H), 4.09–4.04 (m,
1H), 4.07 (s, 5H), 3.99–3.96 (m, 1H), 3.31 (s, 3H), 2.35
(s, 6H); 13C NMR (CDCl3): l 141.4, 137.5, 129.2 (CH),
125.1 (CH), 90.5, 82.6 (CH), 68.7 (CH), 67.8 (CH), 67.7
(CH), 67.6 (CH), 67.0 (CH), 56.9 (CH3), 21.4 (CH3);
MS (EI, 70 eV) m/z (%): 334 (M+, 52), 318 (20), 304
(24), 239 (28), 182 (85), 167 (100), 152 (59); HRMS
calcd for C20H22FeO: 334.1020. Observed: 334.1028.
4.3.1. (R)-(a-Methoxyphenylmethyl)ferrocene, 5a.
A
solution of (R)-(a-hydroxyphenylmethyl)ferrocene 4a
(1.62 g, 5.54 mmol, 98% ee) in methanol (20 mL) with
acetic acid (0.73 mL) was stirred 12 h at rt. The
reaction mixture was neutralized with satd aq.
NaHCO3 solution and methanol was removed under
reduced pressure. The remaining suspension was
extracted with diethyl ether (150 mL). The organic
layers were washed with water and brine and dried over
MgSO4. The crude product was recrystallized from
methanol (11 mL). The ether 5a (1.58 g, 5.16 mmol,
93%) was obtained enantiomerically pure. HPLC analy-
sis (OD, 95% n-heptane, 5% i-propanol, 0.6 mL/min):
retention time (min) 15.7 (R), 27.9 (S); >99.8% ee (R);
mp 94°C; [h]D=+33.8 (c 1.09, CHCl3); IR (KBr): v˜
3099 (m), 2920 (m), 1452 (m), 1080 (s), 1070 (s), 746 (s),
706 (s); 1H NMR (CDCl3): l 7.46–7.27 (m, 5H), 5.02 (s,
1H), 4.29–4.25 (m, 1H), 4.16–4.12 (m, 1H), 4.11–4.07
(m, 1H), 4.06 (s, 5H), 3.98–3.94 (m, 1H), 3.31 (s, 3H);
13C NMR (CDCl3): l 141.4, 128.1 (CH), 127.6 (CH),
127.3 (CH), 90.2, 82.6 (CH), 68.7 (CH), 67.9 (CH), 67.9
(CH), 67.8 (CH), 67.0 (CH), 56.9 (CH3); MS (EI, 70
eV) m/z (%): 306 (M+, 46), 290 (13), 276 (16), 211 (20),
153 (100), 122 (16); HRMS calcd for C18H18FeO:
306.0707. Observed: 306.0708.
4.4. Cross-coupling reactions
2-Iodopyrimidine,13 2-iodopyridine14 and 2-iodoquino-
line15 were prepared according to literature procedures.
4.4.1. (RFc)-1-(2-Pyrimidyl)-2-(a-(R)-methoxy(phenyl)-
methyl)ferrocene, 6a. A solution of (R)-(a-methoxy-
(phenyl)methyl)ferrocene (5a) (464 mg, 1.52 mmol) in
diethyl ether (25 mL) was cooled to −78°C. tert-Butyl-
lithium in pentane (1.5 M, 1.10 mL, 1.65 mmol, 1.1
equiv.) was added dropwise, the mixture was warmed
up to rt and stirred for 1 h. After the mixture had been
cooled to −40°C a solution of ZnBr2 in THF (1.3 M,
1.50 mL, 1.95 mmol, 1.3 equiv.) was added. The mix-
ture was warmed up to rt and stirred for 1 h. The
solvent was then removed under reduced pressure.
For the cross-coupling reaction, a solution of the cata-
lyst was prepared in THF (2 mL) from bis(dibenzyl-
ideneacetone)palladium(0) (28.6 mg, 0.050 mmol) and
tris-o-furylphosphine (23.0 mg, 0.10 mmol) and stirred
5 min at rt. 2-Iodopyrimidine (206 mg, 1.00 mmol) was
added in THF (2 mL) and the mixture was stirred for a
further 5 min. The zinc reagent prepared above was
added as solution in THF (6 mL). The resulting mix-
ture was heated to 60°C for 20 h. After addition of
water, the mixture was extracted with diethyl ether (60
mL). The organic layers were washed with water and
brine and dried over MgSO4. The crude material was
purified by column chromatography (n-pentane/diethyl
ether 3:1) to give 6a as a red oil (285 mg, 0.742 mmol,
74%); [h]D=−207.8 (c 0.49, CHCl3); IR: (film): v˜ 2975
(m), 1569 (s), 1555 (s), 1485 (s), 1398 (s), 1085 (s), 745
(s), 704 (s); H NMR (CDCl3): l 8.69 (d, J=4.9 Hz,
2H), 7.71–7.66 (m, 2H), 7.50–7.43 (m, 2H), 7.40–7.32
(m, 1H), 7.07 (t, 3J=4.9 Hz, 1H), 6.42 (s, 1H), 5.18 (dd,
J=2.5 Hz, 1.4 Hz, 1H), 4.35 (dd, J=2.5 Hz, 1H), 4.12
(dd, J=2.5 Hz, 1H), 3.82 (s, 5H), 3.25 (s, 3H); 13C
NMR (75 MHz, CDCl3): l 170.2, 156.4 (CH), 141.8,
128.1 (CH), 127.9 (CH), 127.5 (CH), 117.2 (CH), 90.7,
80.1 (CH), 79.5, 71.7 (CH), 70.5 (CH), 70.3 (CH), 69.4
(CH), 56.9 (CH3); MS (EI, 70 eV) m/z (%): 384 (M+,
100), 369 (14), 354 (25), 319 (73), 289 (60), 287 (23), 231
(66), 211 (40); HRMS calcd for C22H20FeN2O:
384.0925. Observed: 384.0921.
4.3.2. (R)-(a-Methoxy(2-methylphenyl)methyl)ferrocene,
5b.
A
solution
of
(R)-(a-hydroxy(2-methyl-
phenyl)methyl)ferrocene (4b) (4.50 g, 14.1 mmol, 97%
ee) in methanol (50 mL) with acetic acid (2.5 mL) was
stirred 13 h at rt. Following the procedure described
above, enantiomerically pure 5b (2.11 g, 6.59 mmol,
63%) was obtained after recrystallization from
methanol (14 mL). HPLC analysis (OD, 95% n-hep-
tane, 5% i-propanol, 0.6 mL/min): retention time (min)
8.1 (R), 11.8 (S); >99.8% ee (R); mp 54°C; [h]D=−20.3
(c 0.76, CHCl3); IR (KBr): v˜ 3092 (m), 2936 (m), 1485
(m), 1459 (m), 1105 (s), 1081 (s), 815 (s), 750 (s), 494
1
(s); H NMR (CDCl3): l 7.46–7.41 (m, 1H), 7.27–7.12
(m, 3H), 5.26 (s, 1H), 4.19–4.15 (m, 1H), 4.12–4.06 (m,
2H), 4.10 (s, 5H), 4.07–4.04 (m, 1H), 3.31 (s, 3H), 2.38
(s, 3H); 13C NMR (CDCl3): l 139.8, 135.6, 130.4 (CH),
127.3 (CH), 127.2 (CH), 125.9 (CH), 90.4, 79.3 (CH),
68.7 (CH), 67.8 (CH), 67.6 (CH), 67.3 (CH), 66.6 (CH),
56.8 (CH3), 19.5 (CH3); MS (EI, 70 eV) m/z (%): 320
(M+, 100), 290 (17), 225 (20), 167 (28), 122 (21); HRMS
calcd for C19H20FeO: 320.0864. Observed: 320.0837.
1
3
4.3.3.
(R)-(a-Methoxy(3,5-dimethylphenyl)methyl)-
solution of (R)-(a-hydroxy(3,5-
ferrocene, 5c.
A
dimethylphenyl)methyl)ferrocene (4c) (3.20 g, 10.5
mmol, 93% ee) in methanol (35 mL) with acetic acid
(1.6 mL) was stirred 13 h at rt. Following the procedure
described above, enantiomerically pure 5c (4.14 g, 12.4
mmol, 88%) was obtained after recrystallization from
methanol (25 mL). HPLC analysis (OD, 95% n-hep-
tane, 5% i-propanol, 0.6 mL/min): retention time (min)
8.5 (R), 23.3 (S); >99.8% ee (R); mp 75°C; [h]D=+38.0
(c 1.09, CHCl3); IR (KBr): v˜ 2920 (m), 1608 (m), 1104
(s), 1092 (s), 784 (m), 698 (m), 496 (s); 1H NMR
(CDCl3): l 7.00 (s, 2H), 6.93 (s, 1H), 4.93 (s, 1H),
4.4.2. (RFc)-1-(2-Pyrimidyl)-2-(a-(R)-methoxy(2-methyl-
phenyl)methyl)ferrocene, 6b. Prepared according to the
procedure described above from (R)-(a-methoxy(2-
methylphenyl)methyl)ferrocene 5b (640 mg, 2.00
mmol), tert-BuLi solution (1.47 mL, 2.20 mmol) and
ZnBr2 solution (2.00 mL, 2.60 mmol). The cross-

260
R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
coupling was performed with Pd(dba)2 (38.0 mg, 0.066
mmol), P(o-Fur)3 (30.6 mg, 0.132 mmol) and 2-iodopy-
rimidine (272 mg, 1.32 mmol) and the product 6b was
isolated as a red solid (444 mg, 1.11 mmol, 84%); mp
89°C; [h]D=−221.8 (c 0.44, CHCl3); IR (KBr): v˜ 2918
(m), 1569 (s), 1556 (s), 1482 (s), 1399 (s), 1068 (s), 758
(m), 498 (m); H NMR (CDCl3): l 8.68 (d, J=4.7 Hz,
2H), 7.70–7.66 (m, 1H), 7.34–7.24 (m, 3H), 7.06 (t,
3J=4.7 Hz, 1H), 6.71 (s, 1H), 5.19 (dd, J=2.5 Hz, 1.5
Hz, 1H), 4.40 (dd, J=2.5 Hz, 1H), 4.34 (dd, J=2.5 Hz,
1.5 Hz, 1H), 3.78 (s, 5H), 3.18 (s, 3H), 2.64 (s, 3H); 13C
NMR (CDCl3): l 170.2, 156.4 (CH), 139.9, 136.7, 130.6
(CH), 128.5 (CH), 127.3 (CH), 125.6 (CH), 117.2 (CH),
89.7, 79.7 (CH), 77.5, 71.4 (CH), 70.4 (CH), 70.3 (CH),
69.6 (CH), 56.4 (CH3), 20.5 (CH3); MS (EI, 70 eV) m/z
(%): 398 (M+, 94), 383 (7), 368 (66), 333 (63), 303 (24),
301 (26), 245 (100), 165 (47); HRMS calcd for
C23H22FeN2O: 398.1082. Observed: 398.1088.
(26), 288 (26), 286 (9), 244 (51), 230 (100), 186 (25);
HRMS calcd for C23H21FeNO: 383.0973. Observed:
383.0964.
4.4.5.
(RFc)-1-(2-Pyridyl)-2-(a-(R)-methoxy(2-methyl-
phenyl)methyl)ferrocene, 6e. Prepared according to the
procedure described above from (R)-(a-methoxy(2-
methylphenyl)methyl)ferrocene 5b (640 mg, 2.00
mmol), tert-BuLi solution (1.47 mL, 2.20 mmol) and
ZnBr2 solution (2.00 mL, 2.60 mmol). The cross-cou-
pling was performed with Pd(dba)2 (38.0 mg, 0.066
mmol), P(o-Fur)3 (30.6 mg, 0.132 mmol) and 2-iodopy-
ridine (271 mg, 1.32 mmol) and the product 6e was
isolated as a red oil (381 mg, 0.959 mmol, 73%);
[h]D=−77.1 (c 0.35, CHCl3); IR (film): v˜ 2926 (m), 1586
1
3
1
(s), 1490 (s), 1420 (m), 1107 (m), 1080 (s), 747 (s); H
3
4
NMR (CDCl3): l 8.62 (ddd, J=4.9 Hz, J=1.7 Hz,
5J=0.8 Hz, 1H), 7.68–7.56 (m, 2H), 7.54–7.49 (m, 1H),
3
4
7.34–7.22 (m, 3H), 7.12 (ddd, J=7.5 Hz, J=4.9 Hz,
5J=1.3 Hz, 1H), 6.43 (s, 1H), 4.73 (dd, J=2.6 Hz, 1.5
Hz, 1H), 4.30 (dd, J=2.6 Hz, 1H), 4.24 (dd, J=2.6 Hz,
1.5 Hz, 1H), 3.81 (s, 5H), 3.13 (s, 3H), 2.60 (s, 3H); 13C
NMR (CDCl3): l 159.7, 148.8 (CH), 139.7, 136.6, 135.5
(CH), 130.6 (CH), 128.3 (CH), 127.3 (CH), 125.6 (CH),
122.0 (CH), 120.5 (CH), 88.3, 83.8, 77.6 (CH), 70.2
(CH), 69.8 (CH), 68.8 (CH), 68.3 (CH), 56.2 (CH3),
20.3 (CH3); MS (EI, 70 eV) m/z (%): 397 (M+, 35), 382
(12), 367 (18), 332 (41), 302 (13), 300 (24), 258 (18), 244
(100), 186 (19), 165 (22); HRMS calcd for
C24H23FeNO: 397.1129. Observed: 397.1131.
4.4.3.
(RFc)-1-(2-Pyrimidyl)-2-(a-(R)-methoxy(3,5-
dimethylphenyl)methyl)ferrocene, 6c. Prepared according
to the procedure described above from (R)-(a-
methoxy(3,5-dimethylphenyl)methyl)ferrocene 5c (1.00
g, 3.00 mmol), tert-BuLi solution (2.20 mL, 3.30 mmol)
and ZnBr2 solution (3.30 mL, 3.90 mmol). The cross-
coupling was performed with Pd(dba)2 (57.5 mg, 0.10
mmol), P(o-Fur)3 (46.4 mg, 0.20 mmol) and 2-iodopy-
rimidine (412 mg, 2.00 mmol) and the product 6c was
isolated as a red oil (702 mg, 1.70 mmol, 85%); [h]D=
−173.1 (c 1.33, CHCl3); IR (KBr): v˜ 2922 (m), 1569 (s),
1554 (s), 1484 (s), 1399 (s), 1085 (m); 1H NMR
3
(CDCl3): l 8.68 (d, J=4.9 Hz, 2H), 7.29 (s, 2H), 7.06
3
4.4.6. (RFc)-1-(2-Pyridyl)-2-(a-(R)-methoxy(3,5-dimethyl-
phenyl)methyl)ferrocene, 6f. Prepared according to the
procedure described above from (R)-(a-methoxy(3,5-
dimethylphenyl)methyl)ferrocene (5c) (458 mg, 1.37
mmol), tert-BuLi solution (1.01 mL, 1.51 mmol) and
ZnBr2 solution (1.37 mL, 1.78 mmol). The cross-cou-
pling was performed with Pd(dba)2 (25.9 mg, 0.045
mmol), P(o-Fur)3 (20.9 mg, 0.090 mmol) and 2-iodopy-
ridine (186 mg, 0.900 mmol) and the product 6f was
isolated as a red oil (310 mg, 0.754 mmol, 83%);
[h]D=−40.9 (c 0.22, CHCl3); IR (film): v˜ 2922 (s), 1586
(t, J=4.9 Hz, 1H), 7.00 (s, 1H), 6.35 (s, 1H), 5.17 (dd,
J=2.7 Hz, 1.8 Hz, 1H), 4.35 (dd, J=2.7 Hz, 1H), 4.14
(dd, J=2.7 Hz, 1.8 Hz, 1H), 3.84 (s, 5H), 3.26 (s, 3H),
2.41 (s, 6H); 13C NMR (CDCl3): l 170.2, 156.4 (CH),
141.5, 137.2, 129.0 (CH), 125.9 (CH), 117.2 (CH), 90.8,
80.0 (CH), 79.4, 71.8 (CH), 70.5 (CH), 70.3 (CH), 69.3
(CH), 56.9 (CH3), 21.4 (CH3); MS (EI, 70 eV) m/z (%):
412 (M+, 100), 397 (11), 382 (33), 347 (90), 317 (59), 315
(24), 260 (45), 211 (49); HRMS calcd for C24H24FeN2O:
412.1238. Observed: 412.1246.
1
(s), 1490 (s), 1419 (m), 1083 (s), 815 (m), 786 (m); H
4.4.4.
(RFc)-1-(2-Pyridyl)-2-(a-(R)-methoxy(phenyl)-
NMR (CDCl3): l 8.66–8.61 (m, 1H), 7.65–7.50 (m, 2H),
methyl)ferrocene, 6d. Prepared according to the proce-
dure described above from (R)-(a-methoxy(phenyl)-
methyl)ferrocene 5a (464 mg, 1.52 mmol), tert-BuLi
solution (1.10 mL, 1.65 mmol) and ZnBr2 solution (1.50
mL, 1.95 mmol). The cross-coupling was performed
with Pd(dba)2 (28.6 mg, 0.050 mmol), P(o-Fur)3 (23.0
mg, 0.10 mmol) and 2-iodopyridine (205 mg, 1.00
mmol) and the product 6d was isolated as a red oil (230
mg, 0.600 mmol, 60%); [h]D=−46.4 (c 0.22, CHCl3); IR
(film): v˜ 2815 (w), 1586 (s), 1564 (m), 1490 (s), 1084 (s),
818 (m); 1H NMR (CDCl3): l 8.81–8.62 (m, 1H),
7.69–7.33 (m, 7H), 7.16–7.09 (m, 2H), 6.07 (s, 1H), 4.75
(dd, J=2.7 Hz, 1.5 Hz, 1H), 4.27 (dd, J=2.7 Hz, 1H),
4.04 (dd, J=2.7 Hz, 1.5 Hz, 1H), 3.85 (s, 5H), 3.17 (s,
3H); 13C NMR (CDCl3): l 159.6, 149.1 (CH), 141.4,
135.5 (CH), 128.0 (CH), 128.0 (CH), 127.5 (CH), 121.9
(CH), 120.5 (CH), 88.8, 83.8, 80.3 (CH), 70.3 (CH),
70.1 (CH), 69.0 (CH), 68.2 (CH), 56.6 (CH3). MS (EI,
70 eV) m/z (%): 383 (M+, 39), 368 (15), 353 (17), 318
3
4
5
7.26 (s, 2H), 7.12 (ddd, J=7.3 Hz, J=4.8 Hz, J=1.2
Hz, 1H), 7.00 (s, 1H), 5.96 (s, 1H), 4.75 (dd, J=2.5 Hz
1.5 Hz, 1H), 4.26 (dd, J=2.5 Hz, 1H), 4.06 (dd, J=2.5
Hz, 1.5 Hz, 1H), 3.87 (s, 5H), 3.17 (s, 3H), 2.41 (s, 6H);
13C NMR (CDCl3): l 159.6, 149.1 (CH), 141.1, 137.3,
135.5 (CH), 129.0 (CH), 125.9 (CH), 122.0 (CH), 120.5
(CH), 88.9, 83.9, 80.3 (CH), 70.3 (CH), 70.2 (CH), 69.1
(CH), 68.1 (CH), 56.6 (CH3), 21.5 (CH3); MS (EI, 70
eV) m/z (%): 411 (M+, 34), 396 (14), 395 (14), 381 (17),
346 (46), 316 (23), 314 (13), 272 (38), 259 (100), 210
(21), 186 (20); HRMS calcd for C25H25FeNO: 411.1286.
Observed: 411.1287.
4.4.7.
(RFc)-1-(2-Quinolyl)-2-(a-(R)-methoxy(phenyl)-
methyl)ferrocene, 6g. Prepared according to the proce-
dure described above from (R)-(a-methoxy(phenyl)-
methyl)ferrocene 5a (464 mg, 1.52 mmol), tert-BuLi
solution (1.10 mL, 1.65 mmol) and ZnBr2 solution (1.50

R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
261
mL, 1.95 mmol). The cross-coupling was performed
with Pd(dba)2 (28.6 mg, 0.050 mmol), P(o-Fur)3 (23.0
mg, 0.10 mmol) and 2-iodoquinoline (260 mg, 1.02
mmol) and the product 6g was isolated as a red oil (299
mg, 0.690 mmol, 68%); [h]D=+540 (c 0.01, CHCl3); IR
(film): v˜ 2925 (m), 1617 (m), 1600 (s), 1507 (s), 1084 (s),
6H); 13C NMR (CDCl3): l 160.2, 148.2, 141.7, 137.3,
135.0 (CH), 129.2 (CH), 129.0 (CH), 127.5 (CH), 126.5,
125.9 (CH), 125.5 (CH), 121.0 (CH), 89.9, 82.5, 80.3
(CH), 70.8 (CH), 70.4 (CH), 69.6 (CH), 68.7 (CH), 56.9
(CH3), 21.5 (CH3); MS (EI, 70 eV) m/z (%): 461 (M+,
28), 446 (19), 431 (100), 429 (23), 396 (64), 365 (64), 309
(58), 260 (27), 204 (16); HRMS calcd for C29H27FeNO:
461.1442. Observed: 461.1445.
1
824 (m), 759 (m), 742 (m), 703 (m); H NMR (CDCl3):
3
4
l 8.17–8.05 (m, 2H), 7.80 (d, J=7.7 Hz, J=1.2 Hz,
1H), 7.75–7.64 (m, 4H), 7.55–7.47 (m, 3H), 7.42–7.36
(m, 1H), 6.43 (s, 1H), 4.87 (dd, J=2.6 Hz, 1.4 Hz, 1H),
4.36 (dd, J=2.6 Hz, 1H), 4.22 (dd, J=2.6 Hz, 1.4 Hz,
1H), 3.82 (s, 5H), 3.31 (s, 3H); 13C NMR (CDCl3): l
160.1, 148.1, 141.9, 135.1 (CH), 129.2 (CH), 129.2
(CH), 128.0 (CH), 128.0 (CH), 127.5 (CH), 126.5, 125.5
(CH), 120.9 (CH), 89.7, 82.5, 80.3 (CH), 70.7 (CH),
70.4 (CH), 69.6 (CH), 68.8 (CH), 56.8 (CH3). MS (EI,
70 eV) m/z (%): 433 (M+, 39), 418 (31), 403 (100), 401
(26), 368 (69), 337 (56), 280 (63), 260 (30), 204 (17);
HRMS calcd for C27H23FeNO: 433.1129. Observed:
433.1135.
4.5. Synthesis of the protected ligands 8a–i
4.5.1.
(RFc)-1-(2-Pyrimidyl)-2-(a-(R)-(diphenylphos-
phino)phenylmethyl)ferrocene, 8a. Diphenylphosphine
(0.14 mL, 150 mg, 0.81 mmol) was added to a solution
of 6a (261 mg, 0.679 mmol) in acetic acid (6.4 mL). The
mixture was heated to 60°C for 6 h. After the mixture
had been cooled to rt, the solvent was removed under
reduced pressure and the residual oil was dissolved in
THF (10 mL). Borane dimethyl sulfide complex (1 mL)
was added dropwise and the mixture was stirred 14 h at
rt. After careful hydrolysis, the mixture was extracted
with dichloromethane (60 mL) and the organic layers
were washed with water and brine and dried over
MgSO4. The crude product was purified by column
chromatography (n-pentane/diethyl ether 5:1). 8a was
obtained as a red solid (204 mg, 0.369 mmol, 54%); mp
193°C; [h]D=−161.8 (c 0.88, CHCl3); IR: (KBr): v˜ 3059
(w), 2390 (m), 1570 (s), 1555 (s), 1479 (s), 1400 (s), 701
(s); 1H NMR (CDCl3): l 8.53 (d, 3J=4.8 Hz, 2H),
7.88–7.79 (m, 4H), 7.41–6.84 (m, 13H), 5.02–4.98 (m,
1H), 4.87 (dd, J=2.8 Hz, 1.7 Hz, 1HHH), 4.47 (dd,
J=2.8 Hz, 1H), 3.52 (s, 5H); 13C NMR (CDCl3): l
170.4, 155.9 (CH), 139.4 (d, J=2.9 Hz), 133.4 (CH, d,
J=8.2 Hz), 132.9 (CH, d, J=8.6 Hz), 131.1 (CH, d,
J=5.9 Hz), 130.9 (CH, d, J=2.3 Hz), 130.2 (CH, d,
J=2.4 Hz), 128.3 (CH, d, J=9.4 Hz), 127.8 (CH, d,
J=1.2 Hz), 127.1 (d, J=1.7 Hz), 127.0 (CH, d, J=9.4
Hz), 116.7 (CH), 88.0 (d, J=6.3 Hz), 79.5 (d, J=1.8
Hz), 73.3 (CH, d, J=2.8 Hz), 70.2 (CH), 69.9 (CH),
68.2 (CH), 39.9 (CH, d, J=29.2 Hz); 31P NMR
(CDCl3): l +25.8 (s, br); MS (EI, 70 eV) m/z (%): 552
(M+, 1), 538 (4), 353 (100), 287 (9), 231 (13); HRMS
calcd for C33H30BFeN2P: 552.1589. Observed:
552.1615.
4.4.8. (RFc)-1-(2-Quinolyl)-2-(a-(R)-methoxy(2-methyl-
phenyl)methyl)ferrocene, 6h. Prepared according to the
procedure described above from (R)-(a-methoxy(2-
methylphenyl)methyl)ferrocene (5b) (640 mg, 2.00
mmol), tert-BuLi solution (1.47 mL, 2.20 mmol) and
ZnBr2 solution (2.00 mL, 2.60 mmol). The cross-cou-
pling was performed with Pd(dba)2 (38.0 mg, 0.066
mmol), P(o-Fur)3 (30.6 mg, 0.132 mmol) and 2-iodo-
quinoline (337 mg, 1.32 mmol) and the product 6h was
isolated as a red solid (492 mg, 1.10 mmol, 83%); mp
114°C; [h]D=+742.1 (c 0.47, CHCl3); IR (film): v˜ 2918
(m), 1616 (m), 1600 (s), 1507 (s), 1081 (s), 824 (s), 748
1
(s); H NMR (CDCl3): l 8.13–8.04 (m, 2H), 7.82–7.60
(m, 4H), 7.54–7.47 (m, 1H), 7.36–7.24 (m, 3H), 6.91 (s,
1H), 4.85 (dd, J=2.5 Hz, 1.5 Hz, 1H), 4.34–4.09 (m,
2H), 3.78 (s, 5H), 3.24 (s, 3H), 2.65 (s, 3H); 13C NMR
(CDCl3): l 160.3, 148.0, 140.4, 136.4, 135.1 (CH), 130.4
(CH), 129.3 (CH), 129.0 (CH), 127.8 (CH), 127.5 (CH),
126.4, 125.7 (CH), 125.5 (CH), 121.0 (CH), 89.1, 82.4,
76.7 (CH), 70.3 (CH), 69.4 (CH), 69.1 (CH), 56.5
(CH3), 20.7 (CH3); MS (EI, 70 eV) m/z (%): 447 (M+,
59), 432 (24), 417 (63), 429 (13), 382 (100), 350 (44), 294
(28), 260 (14), 248 (18); HRMS calcd for C28H25FeNO:
447.1286. Observed: 447.1286.
4.5.2.
(RFc)-1-(2-Pyrimidyl)-2-(a-(R)-(diphenylphos-
phino)(2-methylphenyl)methyl)ferrocene, 8b. Prepared
according to the procedure described above from 6b
(351 mg, 0.881 mmol) and diphenylphosphine (0.18
mL, 193 mg, 1.04 mmol). 8b was isolated as a red solid
(154 mg, 0.256 mmol, 29%); mp 184°C; [h]D=−170.3 (c
0.57, CHCl3); IR (KBr): v˜ 3056 (w), 2391 (m), 1570 (s),
4.4.9.
(RFc)-1-(2-Quinolyl)-2-(a-(R)-methoxy(3,5-
dimethylphenyl)methyl)ferrocene, 6i. Prepared according
to the procedure described above from (R)-(a-
methoxy(3,5-dimethylphenyl)methyl)ferrocene 5c (458
mg, 1.37 mmol), tert-BuLi solution (1.01 mL, 1.51
mmol) and ZnBr2 solution (1.37 mL, 1.78 mmol). The
cross-coupling was performed with Pd(dba)2 (25.9 mg,
0.045 mmol), P(o-Fur)3 (20.9 mg, 0.090 mmol) and
2-iodoquinoline (231 mg, 0.906 mmol) and the product
6i was isolated as a red solid (327 mg, 0.709 mmol,
78%); mp 56°C; [h]D=+574.4 (c 0.18, CHCl3); IR
(film): v˜ 2922 (m), 1617 (m), 1600 (s), 1507 (s), 1083 (s),
1
1555 (s), 1480 (s), 1400 (s), 696 (m); H NMR (CDCl3):
3
l 8.52 (d, J=4.8 Hz, 2H), 8.07 (d, J=7.9 Hz, 1H),
7.63–7.55 (m, 2H), 7.38–7.08 (m, 9H), 7.03–6.90 (m,
4H), 4.99–4.95 (m, 1H), 4.91 (dd, J=2.6 Hz, 1.7 Hz,
1H), 4.48 (dd, J=2.6 Hz, 1H), 3.52 (s, 5H), 2.61 (s,
3H); 13C NMR (CDCl3): l 170.2, 155.9 (CH), 138.2, (d,
J=2.4 Hz), 136.8 (d, J=6.4 Hz), 133.5 (CH, d, J=8.2
Hz), 133.1 (CH, d, J=8.2 Hz), 131.2 (CH, d, J=4.6
Hz), 130.7 (CH, d, J=2.9 Hz), 130.5 CH, d, J=2.4
Hz), 130.1 (CH), 128.5 (d, J=3.0 Hz), 128.0 (CH, d,
J=9.4 Hz), 127.1 (CH, d, J=10.0 Hz), 125.5 (CH, d,
J=1.8 Hz), 116.8 (CH), 87.7 (C, d, J=8.9 Hz), 79.6 (d,
1
821 (m), 490 (m); H NMR (CDCl3): l 8.16–8.05 (m,
2H), 7.79 (d, 3J=8.4 Hz, 1H), 7.74–7.64 (m, 2H),
7.54–7.47 (m, 1H), 7.32 (s, 2H), 7.01 (s, 1H), 6.32 (s,
1H), 4.88–4.84 (m, 1H), 4.35 (dd, J=2.6 Hz, 1H),
4.25–4.21 (m, 1H), 3.84 (s, 5H), 3.30 (s, 3H), 2.42 (s,

262
R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
J=1.7 Hz), 73.6 (CH, d, J=3.5 Hz), 70.1 (CH), 69.9
(CH), 68.3 (CH), 35.5 (CH, d, J=28.2 Hz), 21.0 (CH3);
31P NMR (CDCl3): l +28.3 (s, br); MS (EI, 70 eV) m/z
(%): 566 (M+, 1), 552 (3), 367 (100), 302 (8), 299 (9),
245 (6), 243 (6); HRMS calcd for C34H32BFeN2P:
566.1746. Observed: 566.1735.
(s), 1436 (s), 736 (s), 692 (s); 1H NMR (CDCl3): l
8.58–8.54 (m, 1H), 8.12 (d, J=7.5 Hz, 1H), 7.51–7.03
(m, 13H), 6.95–6.85 (m, 4H), 4.92 (s, br, 1H), 4.37–4.32
(m, 2H), 3.52 (s, 5H), 2.61 (s, 3H); 13C NMR (75 MHz,
CDCl3): l 160.2, 147.9 (CH), 138.2 (d, J=2.4 Hz),
137.2 (d, J=6.5 Hz), 135.6 (CH), 133.6 (CH, d, J=8.1
Hz), 133.0 (CH, d, J=8.1 Hz), 131.5 (CH, d, J=4.7
Hz), 130.6 (CH, d, J=2.3 Hz), 130.3 (CH, d, J=2.3
Hz), 130.1 (CH), 128.3, 127.9 (CH, d, J=9.9 Hz), 127.2
(CH, d, J=10.0 Hz), 125.4 (CH, d, J=1.8 Hz), 121.7
(CH), 120.2 (CH), 87.0 (d, J=5.9 Hz), 82.9 (d, J=1.7
Hz), 72.4 (CH, d, J=3.4 Hz), 70.1 (CH), 68.6 (CH),
65.7 (CH), 35.4 (CH, d, J=28.1 Hz), 20.7 (CH3); 31P
NMR (CDCl3): l +28.1 (s, br); MS (EI, 70 eV) m/z
(%): 565 (M+, 1), 551 (3), 366 (100), 301 (6), 298 (11),
244 (8), 242 (7); HRMS calcd for C35H33BFeNP:
565.1793. Observed: 565.1793.
4.5.3.
(RFc)-1-(2-Pyrimidyl)-2-(a-(R)-(diphenylphos-
phino)(3,5-dimethylphenyl)methyl)ferrocene, 8c. Pre-
pared according to the procedure described above from
6c (702 mg, 1.70 mmol) and diphenylphosphine (0.36
mL, 385 mg, 2.07 mmol). 8c was isolated as a red solid
(170 mg, 0.293 mmol, 17%); mp 188°C; [h]D=−137.6 (c
0.58, CHCl3); IR (KBr): v˜ 3057 (w), 2393 (m), 1570 (s),
1
1555 (s), 1480 (s), 1399 (s), 699 (m); H NMR (CDCl3):
3
l 8.53 (d, J=4.9 Hz, 2H), 7.85–7.76 (m, 2H), 7.43–
3
7.31 (m, 5H), 7.19–7.01 (m, 3H), 6.95 (t, J=4.9 Hz,
1H), 6.90–6.82 (m, 4H), 4.99–4.95 (m, 1H), 4.88–4.84
(m, 1HHH), 4.46 (dd, J=2.7 Hz, 1H), 3.55 (s, 5H), 2.33
(s, 6H); 13C NMR (CDCl3): l 170.4, 155.9 (CH), 139.0
(d, J=2.2 Hz), 137.0 (d, J=1.2 Hz), 133.4 (CH, d,
J=8.3 Hz), 133.0 (CH, d, J=8.2 Hz), 130.8 (CH, d,
J=2.2 Hz), 130.2 (CH, d, J=2.4 Hz), 129.4, 129.0
(CH, d, J=5.8 Hz), 128.7 (d, J=2.6 Hz), 128.6 (CH, d,
J=1.8 Hz), 128.2 (CH, d, J=9.3 Hz), 127.0 (CH, d,
J=10.2 Hz), 116.7 (CH), 88.2 (d, J=6.5 Hz), 79.4 (d,
J=1.7 Hz), 73.6 (CH, d, J=3.1 Hz), 70.1 (CH), 69.7
(CH), 68.1 (CH), 39.6 (CH, d, J=28.9 Hz), 21.5 (CH3);
31P NMR (CDCl3): l +26.0 (s, br); MS (EI, 70 eV) m/z
(%): 580 (M+, 1), 566 (3), 381 (100), 316 (11), 259 (8);
HS MS calcd for C35H34BFeN2P: 580.1902. Observed:
580.1916.
4.5.6. (RFc)-1-(2-Pyridyl)-2-(a-(R)-(diphenylphosphino)-
(3,5-dimethylphenyl)methyl)ferrocene,
8f.
Prepared
according to the procedure described above from 6f
(284 mg, 0.690 mmol) and diphenylphosphine (0.15
mL, 161 mg, 0.865 mmol). 8f was isolated as a red solid
(353 mg, 0.609 mmol, 88%); mp 183°C; [h]D=−3.6 (c
1.17, CHCl3); IR (KBr): v˜ 3057 (w), 2394 (s), 1587 (s),
1
1489 (s), 699 (s); H NMR (CDCl3): l 8.64–8.61 (m,
1H), 7.75–7.67 (m, 2H), 7.42–7.27 (m, 6H), 7.12–7.01
2
(m, 4H), 6.89–6.81 (m, 4H), 6.65 (d, J(H,P)=18 Hz,
1H), 4.91 (dd, J=1.0 Hz, 1H), 4.36–4.31 (m, 2H), 3.55
(s, 5H), 2.35 (s, 6H); 13C NMR (CDCl3): l 160.2, 148.3
(CH), 139.0 (d, J=2.3 Hz), 136.8 (d, J=1.2 Hz), 135.4
(CH), 133.3 (CH, d, J=8.2 Hz), 132.9 (CH, d, J=9.0
Hz), 130.7 (CH, d, J=2.3 Hz), 130.0 (CH, d, J=2.3
Hz), 129.3, 129.0 (CH, d, J=5.2 Hz), 128.6, 128.5 (CH,
d, J=1.8 Hz), 128.1 (CH, d, J=9.4 Hz), 127.1 (CH, d,
J=10.2 Hz), 121.8 (CH), 120.1 (CH), 87.5 (d, J=6.4
Hz), 83.1 (d, J=1.7 Hz), 72.1 (CH, d, J=2.9 Hz), 70.1
(CH), 68.5 (CH), 65.4 (CH), 39.2 (CH, d, J=28.8 Hz),
21.5 (CH3); 31P NMR (81 MHz, CDCl3): l +25.9 (s,
br); MS (EI, 70 eV) m/z (%): 579 (M+, 2), 565 (9), 380
(100), 314 (7), 258 (7); HRMS calcd for C36H35BFeNP:
579.1950. Observed: 579.1979.
4.5.4. (RFc)-1-(2-Pyridyl)-2-(a-(R)-(diphenylphosphino)-
(phenyl)methyl)ferrocene, 8d. Prepared according to the
procedure described above from 6d (182 mg, 0.475
mmol) and diphenylphosphine (0.10 mL, 107 mg, 0.575
mmol). 8d was isolated as a red solid (238 mg, 0.432
mmol, 91%); mp 117°C; [h]D=−19.6 (c 0.55, CHCl3);
IR (KBr): v˜ 3060 (w), 2388 (m), 1587 (s), 1490 (s), 1437
1
(m), 698 (s); H NMR (CDCl3): l 8.65–8.61 (m, 1H),
7.85–7.22 (m, 11H), 7.12–7.01 (m, 4H), 6.89–6.78 (m,
4H), 4.95–4.92 (m, 1H), 4.37–4.31 (m, 2H), 3.53 (s, 5H);
13C NMR (CDCl3): l 160.2, 148.2 (CH), 139.5 (d,
J=2.8 Hz), 135.5 (CH), 133.2 (CH, d, J=8.2 Hz),
132.8 (CH, d, J=8.7 Hz), 131.2 (CH, d, J=5.7 Hz),
130.8 (CH, d, J=2.3 Hz), 130.0 (CH, d, J=2.8 Hz),
128.2 (CH, d, J=9.5 Hz), 127.7 (CH, d, J=1.2 Hz),
127.1 (CH, d, J=10.0 Hz), 127.0, 121.8 (CH), 120.1
(CH), 87.3 (d, J=6.0 Hz), 83.0 (d, J=1.2 Hz), 71.9
(CH, d, J=3.5 Hz), 70.1 (CH), 68.6 (CH), 65.4 (CH),
39.4 (CH, d, J=28.7 Hz); 31P NMR (CDCl3): l +25.8
(s, br); MS (EI, 70 eV) m/z (%): 551 (M+, 1), 537 (8),
352 (100), 286 (10), 230 (12); HRMS calcd for
C34H31BFeNP: 551.1637. Observed: 551.1635.
4.5.7. (RFc)-1-(2-Quinolyl)-2-(a-(R)-(diphenylphosphino)-
(phenyl)methyl)ferrocene, 8g. Prepared according to the
procedure described above from 6g (250 mg, 0.577
mmol) and diphenylphosphine (0.12 mL, 128 mg, 0.687
mmol). 8g was isolated as a red solid (109 mg, 0.181
mmol, 31%); mp 98°C; [h]D=+636.0 (c 0.60, CHCl3);
IR (KBr): v˜ 3058 (w), 2394 (m), 1600 (s), 1506 (m), 697
1
(s), 495 (m), 475 (m); H NMR (CDCl3): l 8.24–8.19
(m, 1H), 7.92–7.75 (m, 7H), 7.58–7.50 (m, 1H), 7.45–
6.96 (m, 11H), 6.75–6.67 (m, 2H), 5.06–5.03 (m, 1H),
4.50–4.46 (m, 1H), 4.41 (dd, J=2.6 Hz, 1H), 3.52 (s,
5H); 13C NMR (CDCl3): l 161.1, 147.5, 139.9 (d,
J=2.1 Hz), 135.0 (CH), 133.2 (CH, d, J=8.3 Hz),
132.9 (CH, d, J=8.1 Hz), 131.2 (CH, d, J=5.8 Hz),
130.8 (CH, d, J=2.4 Hz), 130.0 (CH, d, J=2.5 Hz),
129.5 (CH), 129.1 (d, J=8.8 Hz), 128.4 (CH), 128.2
(CH, d, J=9.9 Hz), 127.8 (CH), 127.7 (CH), 127.1
(CH, d, J=9.6 Hz), 126.2, 125.5 (CH), 120.6 (CH), 88.4
(d, J=5.6 Hz), 81.5 (d, J=1.8 Hz), 72.6 (CH, d, J=3.0
Hz), 70.3 (CH), 69.0 (CH), 66.4 (CH), 39.1 (CH, d,
4.5.5. (RFc)-1-(2-Pyridyl)-2-(a-(R)-(diphenylphosphino)-
(2-methylphenyl)methyl)ferrocene, 8e. Prepared accord-
ing to the procedure described above from 6e (333 mg,
0.838 mmol) and diphenylphosphine (0.18 mL, 193 mg,
1.04 mmol). 8e was isolated as a red solid (469 mg,
0.830 mmol, 99%); mp 216°C; [h]D=−55.9 (c 0.57,
CHCl3); IR (KBr): v˜ 3054 (w), 2396 (m), 1588 (s), 1491

R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
263
J=29.4 Hz); 31P NMR (CDCl3): l +25.7 (s, br); MS
(EI, 70 eV) m/z (%): 601 (M+, 1), 587 (4), 402 (100), 336
(17), 280 (17); HRMS calcd for C38H33BFeNP:
601.1793. Observed: 601.1783.
diethylamine (0.5 mL) and heated to 50°C for 30 min.
Afterwards, the solvent and volatile compounds were
removed in vacuo. This procedure was repeated four
times. The deprotection can be monitored by 31P NMR.
To remove traces of diethyl amine, the solvent for the
catalytic reaction (THF or dichloromethane) was added
and removed again in vacuo repeatedly (Table 6).
4.5.8. (RFc)-1-(2-Quinolyl)-2-(a-(R)-(diphenylphosphino)-
(2-methylphenyl)methyl)ferrocene, 8h. Prepared accord-
ing to the procedure described above from 6h (460 mg,
1.03 mmol) and diphenylphosphine (0.22 mL, 235 mg,
1.26 mmol). 8h was isolated as a red solid (482 mg,
0.783 mmol, 76%); mp 152°C; [h]D=+676.7 (c 0.62,
CHCl3); IR (KBr): v˜ 3058 (w), 2394 (m), 1601 (s), 698
(m), 490 (s), 476 (s); 1H NMR (CDCl3): l 8.17–8.07 (m,
2H), 7.84 (d, J=9.0 Hz, 1H), 7.78–6.98 (m, 16H),
6.78–6.70 (m, 2H), 5.00–4.97 (m, 1H), 4.54 (dd, J=2.7
Hz 1.3 Hz, 1H), 4.45 (dd, J=2.7 Hz, 1H), 3.55 (s, 5H),
2.77 (s, 3H); 13C NMR (CDCl3): l 161.0, 147.4, 138.4
(d, J=2.2. Hz), 137.0 (d, J=6.5 Hz), 135.0 (CH), 133.7
(CH, d, J=8.2 Hz), 133.1 (CH, d, J=8.4 Hz), 131.5
(CH, d, J=4.7 Hz), 130.6 (CH, d, J=2.2 Hz), 130.2
(CH, d, J=2.3 Hz), 130.0 (CH), 129.5 (CH), 129.4,
127.9 (CH, d, J=9.3 Hz), 127.2 (CH, d, J=2.6 Hz),
127.0 (CH, d, J=9.9 Hz), 126.2, 125.5 (CH), 120.8
(CH), 87.7 (d, J=5.3 Hz), 81.7, 72.8 (CH, d, J=3.5
Hz), 70.2 (CH), 69.2 (CH), 67.3 (CH), 35.6 (CH, d,
J=28.1 Hz), 21.8 (CH3); 31P NMR (CDCl3): l +28.5 (s,
br); MS (EI, 70 eV) m/z (%): 615 (M+, 1), 601 (4), 430
(11), 416 (100), 351 (7), 348 (17), 294 (9), 292 (11);
HRMS calcd for C39H35BFeNP: 615.1950. Observed:
615.1952.
Table 6. 31P NMR (CDCl3) shifts of 7a–i
Ar%
Ar=Phenyl
Ar=o-Tolyl
Ar=3,5-Xylyl
2-Pyrimidyl
2-Pyridyl
2-Quinolyl
7a: l +8.6
7d: l +8.5
7g: l +8.8
7b: l +14.5
7e: l +14.4
7h: l +15.2
7c: l +7.9
7f: l +8.1
7i: l +8.4
4.7. Hydroboration of styrene
The freshly deprotected ligand 7a–i and [Rh(cod)2]BF4
(4.1 mg, 0.010 mmol, 1 mol%) were dissolved in THF
(3 mL) and stirred 20 min at rt. Styrene (0.11 mL, 1.0
mmol) and tetradecane as internal standard were added
and the mixture was cooled to the indicated tempera-
ture before catechol borane (0.12 mL, 1.1 mmol) was
added. The reaction was followed by GC. Aliquots
were treated with a mixture of 2N sodium hydroxide
solution and hydrogen peroxide solution (30%). The
reaction was quenched by adding methanol (1 mL), 2N
sodium hydroxide solution (1.5 mL) and hydrogen per-
oxide solution (30%, 0.1 mL). The mixture was then
extracted with diethyl ether (60 mL) and the organic
layers were washed with 1N sodium bisulfite solution,
water and brine and dried over MgSO4. The crude
product was dissolved in diethyl ether and filtered
through a short pad of silica gel. The enantiomeric
excess was determined by HPLC (OD-H, 95% n-hep-
tane, 5% i-propanol, 0.6 mL/min); retention time (min):
1-phenylethanol: 15.0 (R), 17.5 (S); 2-phenylethanol:
16.1).
4.5.9.
(RFc)-1-(2-Quinolyl)-2-(a-(R)-(diphenylphos-
phino)(3,5-dimethylphenyl)methyl)ferrocene, 8i. Prepared
according to the procedure described above from 6i
(302 mg, 0.655 mmol) and diphenylphosphine (0.14
mL, 150 mg, 0.806 mmol). 8i was isolated as a red solid
(135 mg, 0.215 mmol, 33%); mp 95°C; [h]D=+618.4 (c
0.63, CHCl3); IR (KBr): v˜ 3057 (w), 2395 (m), 1600 (s),
1
693 (m), 491 (s); H NMR (CDCl3): l 8.19 (d, J=8.6
Hz, 1H), 7.87 (d, J=8.6 Hz, 1H), 7.84–7.75 (m, 4H),
7.57–7.50 (m, 1H), 7.47 (s, 2H), 7.38–7.07 (m, 7H),
7.03–6.95 (m, 1H), 6.90 (s, 1H), 6.76–6.68 (m, 2H), 5.03
(dd, J=2.6 Hz, 1.1 Hz, 1H), 4.48 (dd, J=2.6 Hz, 1.1
Hz, 1H), 4.41 (dd, J=2.6 Hz, 1H), 3.54 (s, 5H), 2.36 (s,
6H); 13C NMR (CDCl3): l 161.1, 147.5, 139.4 (d,
J=2.4 Hz), 133.2 (CH, d, J=8.1 Hz), 133.0 (CH; d,
J=8.0 Hz), 130.7 (CH, d, J=2.3 Hz), 130.0 (CH, d,
J=2.4 Hz), 129.5 (CH), 129.3 (CH, d, J=3.3 Hz),
129.1 (CH, d, J=6.1 Hz), 128.6 (d, J=2.8 Hz), 128.5
(CH, d, J=1.8 Hz), 128.4 (CH), 128.1 (CH, d, J=9.4
Hz), 127.6 (CH), 127.0 (CH, d, J=9.6 Hz), 126.2, 125.5
(CH), 120.7 (CH), 88.7 (d, J=6.5 Hz), 81.6 (d, J=1.7
Hz), 72.8 (CH, d, J=9.0 Hz), 70.3 (CH), 68.9 (CH),
66.5 (CH), 38.9 (CH, d, J=29.3 Hz), 22.3 (CH3); 31P
NMR (CDCl3): l +26.0 (s, br); MS (EI, 70 eV) m/z
(%): 629 (M+, 1), 615 (8), 430 (100), 364 (8), 308 (5);
HRMS calcd for C40H37BFeNP: 629.2106. Observed:
629.2084.
4.8. Allylic alkylation
The freshly deprotected ligand 7a–i (17 mmol, 3.4
mol%) and allylpalladium chloride (dimer, 1.6 mg; 4.4
mmol, 0.87 mol%) were dissolved in dichloromethane (3
mL) and stirred 15 min at rt. 3-Acetoxy-1,3-diphenyl-
propene (126 mg, 0.50 mmol) in dichloromethane (1
mL), N,O-bistrimethylsilylacetamide (0.25 mL, 210 mg,
1.01 mmol), dimethyl malonate (0.11 mL, 130 mg, 0.96
mmol) and potassium acetate (2.3 mg, 23 mmol, 4.6
mol%) were added. The reaction was followed by thin
layer chromatography (n-pentane/diethyl ether 6:1).
After 20 h satd NH4Cl solution was added and the
mixture was extracted with dichloromethane (60 mL).
The organic layers were washed with brine and dried
over MgSO4. The crude product was purified by
column chromatography (n-pentane/diethyl ether 5:1).
The enantiomeric excess was determined by HPLC
(OD-H, 97% n-heptane, 3% i-propanol, 0.4 mL/min);
retention time (min): 21.5 (R), 23.1 (S)).
4.6. Deprotection
Prior to use in catalysis, a quantity of the required
protected ligand 8a–i (10 to 20 mg) was dissolved in

264
R. J. Kloetzing et al. / Tetrahedron: Asymmetry 14 (2003) 255–264
Klusacek, H.; Marquarding, D.; Ugi, I. Angew. Chem.
Acknowledgements
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