New chiral ferrocenyloxazolines: The first planar chiral triferrocenylmethane derivative and its use in asymmetric catalysis

Article abstract of DOI:10.1016/j.jorganchem.2009.01.057

New planar chiral enantiopure ferrocenyloxazolines have been prepared including ferrocenyldiphenylmethanol, diferrocenylphenylmethanol and triferrocenylmethanol derivatives (S,pR)-10 - (S,pR)-12, the latter being the first chiral triferrocenylmethanol der

Full text of DOI:10.1016/j.jorganchem.2009.01.057

Journal of Organometallic Chemistry 694 (2009) 2047–2052
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
New chiral ferrocenyloxazolines: The first planar chiral triferrocenylmethane
derivative and its use in asymmetric catalysis
José Ramon Garabatos-Perera, Holger Butenschön *
Institut für Organische Chemie, Leibniz Universität Hannover, Schneiderberg 1B, D-30167 Hannover, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
New planar chiral enantiopure ferrocenyloxazolines have been prepared including ferrocenyldiphenyl-
methanol, diferrocenylphenylmethanol and triferrocenylmethanol derivatives (S,pR)-10 – (S,pR)-12, the
latter being the first chiral triferrocenylmethanol derivative. The ferrocenyldiphenylmethanol
derivative (S,pR)-10 has been crystallographically characterized. Asymmetric ethylation of some aryl-
aldehydes using diethylzinc in the presence of the planar chiral triferrocenylmethanol derivative
Received 12 December 2008
Received in revised form 28 January 2009
Accepted 30 January 2009
Available online 10 February 2009
(
S,pR)-12 afforded good yields and ees, which were higher than those obtained with related
Keywords:
ferrocenyloxazolines.
Ferrocene ligands
Asymmetric catalysis
Oxazolin
Ó 2009 Elsevier B.V. All rights reserved.
Chirality
Triferrocenylmethanol
1
. Introduction
Chiral ferrocenyloxazolines 1 give access to valuable catalysts
Here, we report on the synthesis of some new complexes of types 1
and 2 including some bearing diphenylhydroxymethyl, ferro-
cenylphenylhydroxymethyl and diferrocenylhydroxymethyl sub-
stituents E. In addition, some catalytic properties of the latter
were evaluated.
for a variety of enantioseletive reactions [1,2]. This is due to the
fact that a large number of chiral ferrocenyloxazolines 1 are readily
accessible in enantiomerically pure form from ferrocene carboxylic
acid and enantiopure 2-amino alcohols, which are available by
reduction of respective
a
-amino acids thus defining the substitu-
2. Results and discussion
ent R. In addition, the oxazoline substituent facilitates
a
stereoselective metalation at C-2 resulting in planar chiral ferroce-
The coordination of oxazoline moieties at metal atoms is the ba-
sis for important ortho metalation reactions as well as of transition
metal catalyzed asymmetric transformations [2,6,7]. Along with
the oxazoline N and O atoms, substituents R and E in 1 and 2
may offer additional possibilities for coordination at metal atoms.
nyloxazolines after electrophilic quench with E [3,4]. In this con-
0
text phosphinoferrocenyloxazolines (2, E ¼ PR ) have gained
2
particular importance as bidendate catalyst ligands [2,5].
O
O
R
R
N
N
2
E
Fe
Fe
O
O
OH
R'
CO Me
N
N
2
R'
1
2
Fe
Fe
4
(
S)-3
*
Corresponding author. Tel.: +49 511 762 4661/4662; fax: +49 511 762 4616.
E-mail address: holger.butenschoen@mbox.oci.uni-hannover.de (H. Butenschön).
0
022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.01.057

2
048
J.R. Garabatos-Perera, H. Butenschön / Journal of Organometallic Chemistry 694 (2009) 2047–2052
With respect to substituent R this implies the use of amino alco-
hols bearing additional functionality. Starting from (S)-serine,
Richards prepared some interesting ferrocenyloxazolines such as
O
1. BuLi, TMEDA
iPr
N
Et O, –78 °C
2
0
methyl ester (S)-3 (ee > 95%), from which alcohols 4 (R = H, Me,
Fe
2.
O
R, R' = Ph, Fc
Et, Ph) and the respective methyl ethers were obtained in high
yields [8]. In this context we prepared the new ferrocenyloxazo-
R
R'
3
+
. H O
(
S)-9
3
0
lines (S)-5 and (S)-6 from (S)-4 (R = Me) by deprotonation followed
by treatment with chlorotrimethylsilane or allylbromide in 64%
and 48% yield, respectively. (S)-5 and (S)-6 are precursors of 1,2-
disubstituted derivatives with a masked functionality at the oxaz-
oline side arm. In addition, (S,pR)-7 and (S,pS)-8 were prepared in
O
O
O
iPr
iPr
iPr
HON
HON
HON
3
1% and 63% yield, respectively, from Richard’s methyl ether by
Fe
Fe
Fe
treatment with BuLi/TMEDA at ꢀ78 °C followed by electrophilic
quench with chlorodiphenylphosphane or benzophenone. The ste-
reochemical assignments are based on the analogy to published
reactions [4,9].
Fe
Fe
Fe
(
S,pR)-10
96 %)
(S)-11
(3:1, 80 %)
(S,pR)-12
(
(61 %)
O
OSiMe3
N
Me
Me
Fe
The structure shows that the phenyl groups adopt a conformation al-
most perpendicular to the cyclopentadienyl plane, which is almost
coplanar with that of the conjugated oxazoline ring. The hydroxy
group shows a H bridge to the oxazoline N atom, a feature, which
has also been observed by Bolm in the structure of (S,pR)-13 as well
as in that of a related tricarbonylrhenium complex [16–18].
(
S)-5
O
O
N
Me
Me
Me
Fe
O
tBu
HON
(
S)-6
Fe
PPh2
O
OMe
Me
N
Fe
(
S,pR)-13
(
S,pR)-7
OH
Ph C
2
O
OMe
Me
N
Me
Fe
(
S,pS)-8
In connection with our interest in triferrocenylmethane deriva-
tives [10,11] we envisaged a combination of this motif with the
option of planar chirality resulting from respective ferrocenylox-
azolines. Therefore, we prepared (S)-9 [1,5], whose diastereoselec-
tive metalation under modified Sammakia conditions followed
by quench with benzophenone, benzoylferrocene [12,13] or
ferrocenoylferrocene [14,15] afforded complexes (S,pR)-10, 11,
and (S,pR)-12 in 96%, 80%, and 61% yield, respectively, with 11
having been formed as a 3:1 diastereomeric mixture. To our
knowledge (S,pR)-12 is the first known chiral triferrocenylmetha-
nol derivative. All three products were identified spectroscopi-
cally with all spectra being in full accord with the assigned
formulas. In addition, it was possible to obtain crystals of
Fig. 1. Structure of (S,pR)-10 in the crystal. Selected bond lengths [pm], angles [°]
and dihedral angles [°]: C6–C11 146.3(4), C7–C17 154.7(4), C11–N 126.2(4), C11–
O1 136.4(3), C17–O2 142.9(3), C17–C18 152.5(4), C17–C24 152.9(4), O2–C17–C7
110.4(3), N–C11–C6 129.0(3), N–C12–C14 112.0(3), C7–C6–C11 128.3(3), N–C11–
(S,pR)-10 suitable for an X-ray crystal structure analysis (Fig. 1)
C6–C7 –6.8, N–C11–C6–C10 176.5, O2–C17–C7–C6 –51.7, C25–C24–C17–C7 –84.6,
C23–C18–C17–C7 20.8, C29–C24–C17–C7 91.4.
from tert-butyl methyl ether (TBME).

J.R. Garabatos-Perera, H. Butenschön / Journal of Organometallic Chemistry 694 (2009) 2047–2052
2049
5
mol% L*
Et Zn
2
O
OH
Et
Fe
R
H
toluene
R
H
Zn
O
Fe
Ferrocenyloxazolines bearing alkylated or arylated hydroxymethyl
substituents have been used as catalysts for the asymmetric alkyl-
ation and alkynylation of aldehydes [16,17,19]. Therefore, we be-
came interested in testing complexes (S,pR)-10 and (S,pR)-12 as
catalysts for this reaction. The results of the alkylation of some aryl
aldehydes with diethylzinc are summarized in Table 1, and for the
purpose of comparison those obtained by using the closely related
Zn
O
H
Fe
N
O
Fig. 2. Proposed transition state for the ethylation of benzaldehyde with Et
2
Zn
catalyzed by (S,pR)-12.
(S,pR)-13 as catalyst are also included [16,17].The data in Table 1
show that catalysis by (S,pR)-10 or by (S,pR)-12 has the same stereo-
chemical outcome as that with (S,pR)-13, all products show R con-
figuration. While the reaction times were somewhat longer than
with (S,pR)-13 the yields and the ees obtained are in the range of
that with (S,pR)-13 or even somewhat higher. Particularly the reac-
tions catalyzed by the triferrocenylmethanol derivative (S,pR)-12
are successful giving the highest ees in most cases.
With respect to the transition state we believe that the situation
described by Bolm et al. [17] is enhanced by the additional steric
bulk of the two ferrocenyl substituents in place of the two phenyl
groups in (S,pR)-13 thereby further stabilizing the transition state
leading to the R product as compared to that leading to the S prod-
uct (Fig. 2). The proposed transition state shows a delicate combi-
nation of the central chirality located at the oxazoline carbon atom
and the planar chirality of the disubstituted ferrocene moiety [20]:
there is obviously cooperation resulting in an efficient steric
shielding of the face of the O–Zn–N seven membered ring, at which
the isopropyl group and the unsubstituted cyclopentadienyl ligand
of the disubstituted ferrocene moiety are located. The higher steric
bulk of the other two ferrocene moieties as compared to phenyl
groups will presumably reduce the conformational flexibility of
the system and thereby stabilize this transition state.
a hydroxydiphenylmethyl substituent at the other cyclopentadi-
enyl ligand thereby lacking planar chirality [19]. The aldehydes
listed in Table 1 were used for testing this reaction with (S,pR)-
1
0 and (S,pR)-12 as catalysts. However, while the yields achieved
were up to 92%, the enantiomeric excesses remained below 20%.
3. Conclusion
In addition to a number of new enantiopure ferrocenyloxazo-
lines, we have prepared the planar chiral triferrocenylmethanol
catalyst (S,pR)-12, which behaves superior to related ones in the
ethylation of aryl aldehydes. In the proposed transition state there
appears to be a cooperation between the central chirality of the
oxazolinyl substituent, the planar chirality of the disubstituted fer-
rocene moiety and the steric bulk of the two other ferrocenyl sub-
stituents, presumably resulting in a reduction the conformational
flexibility of the system.
4. Experimental
General: All operations involving air sensitive materials were
performed under argon using standard Schlenk techniques. Diethyl
ether (EE), THF, and benzene were dried over Na/K – benzophe-
none; petroleum ether (PE) and tert-butyl methyl ether (TBME)
Attempts to perform asymmetric arylations [21] with (S,pR)-10
or with (S,pR)-12 carried out in cooperation with the Bolm group
gave, however, disappointing results: While the results with
(S,pR)-10 were similar to those obtained with (S,pR)-13 [22], the
were dried over CaCl . Dibutyl ether and dichloromethane were
2
reactions with (S,pR)-12 gave almost no stereoselection [23].
Hou has reported the asymmetric addition of phenylethyne to
aldehydes giving the respective propargylic alcohols in high enan-
tiomeric excess with a series of chiral ferrocenyloxazolines bearing
dried over CaH2 and distilled under Ar prior to use. Starting
materials were either purchased or prepared according to litera-
ture procedures. IR: Perkin Elmer 2000, FT 1170 (ATR). – 1
H
NMR: Bruker AVS 400 (400.1 MHz). Chemical shifts refer to
Table 1
Asymmetric ethylation of arylaldehydes.
*
Yielda (%)
Absolute configurationd
Entry
1
RCHO
L
Reaction time (h)
ee (%)
C
C
C
6
H
6
H
6
H
5
CHO
5
CHO
5
CHO
(S,pR)-10
(S,pR)-13
(S,pR)-12
(S,pR)-10
(S,pR)-13
(S,pR)-12
(S,pR)-10
(S,pR)-13
(S,pR)-12
(S,pR)-10
(S,pR)-13
(S,pR)-12
(S,pR)-10
(S,pR)-12
24
6
24
24
6
24
24
6
24
24
9
97
83
95
80
94
80
87
89
99
98
93
95
94
98
83b
93
R
R
R
R
R
R
R
R
R
R
R
R
R
R
2
3
4
5
6
7
8
9
1
1
1
1
1
[16,17]
b
97
b
p-ClC
p-ClC
p-ClC
6
6
6
H
H
H
4
4
4
CHO
CHO
CHO
85
[16,17]
[16,17]
86
b
97
b
PhCH@CHCHO
PhCH@CHCHO
PhCH@CHCHO
p-MeOC
p-MeOC
p-MeOC
70
78
b
80
b
0
6
H
6
H
6
H
4
CHO
4
CHO
4
CHO
84
1 [16,17]
91
b
2
3
4
24
24
24
90
90
c
1-Naphtaldehyde
1-Naphtaldehyde
c
97
a
Yield in % based on aldehyde.
b
c
Determined by GC.
Determined by 1H NMR.
d
Configurations were assigned by comparison of the specific rotations with those of known compounds.

2
050
J.R. Garabatos-Perera, H. Butenschön / Journal of Organometallic Chemistry 694 (2009) 2047–2052
+
+
d
TMS = 0 ppm or to residual solvent peaks. br: broad, unresolved
166.9 (+, OCN) ppm. - MS (ESI, ES ): m/z = 354 [M+H ]. HRMS (ESI)
1
3
signal – C NMR: Bruker AVS 400 (100 MHz). Chemical shifts refer
to dTMS = 0 ppm or to residual solvent peaks. – MS (EI, ESI-MS):
AMD 604 Inectra, Finnigan MAT 112, MAT 312, 70 eV. – HRMS:
Finnigan MAT 312, VG Autospect. – Melting points: Electrothermal
IA 9200. GC: Hewlett Packard HPGC, SE-54 capillary column, FID
detector 19231 D/E.
2
(C19H24FeNO ): Calc.: 354.1156; found: 354.1147 [M+H].
4.3. General procedure for the ortho-functionalization of
ferrocenyloxazolines (GP1)
To a dark orange solution of the ferrocenyloxazoline and TMEDA
in anhydrous Et
at –78 °C. After stirring at –78 °C for 4 h the electrophile was added
and the solution was allowed to warm to 25 °C over 14 h. H O was
added and the reaction crude dissolved in EE. The organic layer was
. The solvent
2
O, a solution of BuLi in hexane was added dropwise
4
.1. (S)-2-Ferrocenyl-4-(1-trimethylsilyloxy-1-methylethyl)oxazoline
[(S)-5]
2
washed with water (3 ꢁ 20 mL) and dried over MgSO
4
A suspension of (S)-1-(2-ferrocenyl-4,5-dihydrooxazol-4-yl)-1-
methylethanol [3] (0.120 g, 0.4 mmol), imidazol (0.122 g,
.8 mmol) and Me SiCl (0.10 mL, 0.8 mmol) in anhydrous THF
15 mL) was stirred at 25 °C for 24 h. Hydrolysis was performed
by addition of a saturated aqueous solution of NaHCO (20 mL).
The reaction mixture was diluted with TBME (100 mL) and the or-
ganic layer was washed with H
O (3 ꢁ 25 mL), dried over MgSO
and the solvent was removed at reduced pressure. Column chro-
matography (SiO
, 25 ꢁ 2.5 cm, PE/EE 9:1) gave pure (S)-2-ferroce-
nyl-4-(1-trimethylsilyloxy-methylethyl)oxazoline [(S)-5] (0.095 g,
was removed under reduced pressure, giving the pure compound
after recrystallization or column chromatography.
1
(
3
4.4. (S,pR)-2-(2-Diphenylphosphanylferrocenyl)-4-(1-methoxy-1-
3
methylethyl)oxazoline [(S,pR)-7]
2
4
,
GP1; (S)-2-Ferrocenyl-4-(1-methoxy-1-methylethyl)oxazoline
0
[
(S)-4, R = Me] [8] (0.309 g, 0.9 mmol), TMEDA (0.2 mL, 1.2 mmol);
2
Et
0.4 mL, 2.2 mmol), column chromatography (SiO
followed by EE/Et N 20:1) gave pure (S,pR)-7 (0.151 g, 0.3 mmol,
2
O (3.6 mL), BuLi (0.8 mL, 1.6 M in hexane, 1.3 mmol), Ph
2
PCl
(
2
, 25 ꢁ 2 cm, EE
0
.2 mmol, 64%) as a red liquid.
ꢀ1
3
IR (ATR):
261 (s), 1126 (s), 1086 (s), 1019 (s, SiOC), 793 (s, SiOC). H NMR
):d 0.12 [s, 9H, Si(CH ], 1.20 (s, 3H, CCH ), 1.37
), 4.02 (dd, ABX line system, trans = 7.2 Hz,
cis = 9.8 Hz, 1H, NCH), 4.19 (s, 5H, CpH), 4.24 (dd, ABX line system,
m
~ ¼ 2963 cm (w), 2920 (w), 2851 (w), 1569 (s, C@N),
1
31%, >95% de) as a red liquid. The configuration assignment is
1
based on literature precedence [4,9].
(
400 MHz, CDCl
s, 3H, CCH
J
J
3
3
)
3
3
D
ꢀ1
3
½aꢂ
¼ ꢀ62:5 (c = 0.176, CHCl ). IR (ATR):
m
~ ¼ 3075 cm (w,
20
3
(
3
J
1
3
2
@CH), 2970 (w), 2925 (w), 2828 (w), 1618 (s, C@N). H NMR
3
(400 MHz, CDCl ): d 0.87 (s, 3H, CCH ), 1.12 (s, 3H, CCH ), 3.14 (s,
3
3
3
gem = –8.8 Hz, Jcis = 9.8 Hz, 1H, OCH
2
), 4.31 (m, 2H, CpR), 4.38 (dd,
), 4.72 (m,
H, CpR), 4.76 (m, 1H, CpR) ppm. C NMR (100 MHz, BB, HMBC,
HMQC, CDCl ):d 2.5 [Si(CH ], 24.3 (CCH ), 28.8 (CCH ), 68.7
OCH ), 68.9 (CH-CpR), 69.0 (CH-CpR), 69.4 (CH-CpH), 70.10 (CH-
CpR), 70.12 (CH-CpR), 70.5, (CR-CpR), 74.9 (NCHCOSi), 76.2
3
2
3 2
3H, OCH ), 3.79 (dd, ABX line system, J = J = 8.0 Hz, 1H, CH ), 3.86
ABX line system, Jtrans = 7.3 Hz, Jgem = –8.7 Hz, 1H, OCH
2
13
(m, 1H, CpR), 3.90 (dd, ABX line system, J = J = 8.0 Hz, 1H, NCH),
.15 (dd, ABX line system, J = J = 9.1 Hz, 1H, CH ), 4.42 (m, 1H,
CpR), 4.46 (s, 5H, CpH), 5.0 (m, 1H, CpR), 7.34–7.44 (m, 6H, Ph),
.60–7.65 (m, 2H, Ph), 7.80–7.75 (m, 2H, Ph) ppm. 13C NMR
(100 MHz, BB, HMQC, HMBC, CDCl ): d 18.9 (CCH ), 22.4 (CCH ),
1
4
2
3
3
)
3
3
3
(
2
7
+
+
3
3
3
(
(
NCH), 167.0 (OC@N) ppm. MS (ESI, ES ): m/z = 386 [M+H ]. HRMS
ESI) (C19 28FeNO Si): Calc.: 386.1239; found: 386.1232 [M+H].
4
7
9.4 (OCH
3.8 [CFcC@N], 74.0 (NCH), 74.2 [d, JP-C = 16.7 Hz, CFcP], 76.3
), 78.4 (d, JP-C = 14.5 Hz, CHCpR), 127.8 (d, JP-C = 7.2 Hz, CPh),
28.0 (d, JP-C = 6.7 Hz, CPh), 130.7 (d, JP-C = 2.7 Hz, CPh), 131.0 (d,
Ph), 131.1 (d, P-C = 9.7 Hz, Ph), 131.5 (d,
Ph), 134.1 (d, P-C = 11.4 Hz, Ph), 135.2 (d,
P-C = 16.4 Hz, CPh), 164.5 (OCN) ppm. P NMR (121.5 MHz, CDCl ):
3 2
), 68.6 (CH ), 71.16 (CHCpH), 71.3 (CHCpR), 73.7 (CHCpR),
H
2
(COCH
3
4
.2. (S)-2-Ferrocenyl-4-[1-(2-propenoxy)-1-methylethyl]oxazoline
1
[(S)-6]
JP-C = 2.5 Hz,
C
J
C
JP-C = 9.1 Hz,
C
J
C
3
1
To a suspension of (S)-1-(2-ferrocenyl-4,5-dihydrooxazol-4-yl)-
-methylethanol [3] (0.134 g, 0.4 mmol) and NaH (0.400 g, 60% in
J
3
+
+
+
1
2
d 27.4 (PPh ) ppm. MS (ESI, ES ): m/z = 528 [M+O+H ], 512 [M+H ],
5
+
mineral oil, 10.0 mmol) in anhydrous THF (40 mL) under nitrogen,
allyl bromide (0.25 mL, 2.4 mmol) was added and the reaction mix-
ture was heated at reflux for 3 h until no starting material re-
mained (TLC, EE). Hydrolysis was performed by addition of a
50 [M+O+Na ]. HRMS (ESI) (C29
2
H31FeNO ): Calc.: 512.1442;
found: 512.1453 [M+H].
4.5. (S,pS)-2-(2-Diphenylhydroxymethylferrocenyl)-4-(1-methoxy-1-
saturated aqueous solution of NaHCO
ture was diluted with EE (25 mL), and the organic layer was
washed with H , and the solvent
O (3 ꢁ 25 mL), dried over MgSO
was removed at reduced pressure. Column chromatography
SiO
3
(25 mL). The reaction mix-
methylethyl)-oxazoline [(S,pS)-8]
2
4
GP1; (S)-2-Ferrocenyl-4-(1-methoxy-1-methylethyl)oxazoline
0
[
(S)-4, R = Me] [8] (0.174 g, 0.5 mmol), TMEDA (0.1 mL, 0.7 mmol),
(
2
, 25 ꢁ 4 cm, PE/EE 7:3) gave pure (S)-2-ferrocenyl-4-(1-allyl-
Et
none (0.206 g, 1.1 mmol), column chromatography (SiO
vated with a 5% Et Cl
2
2
O (2.0 mL), BuLi (0.4 mL, 1.6 M in hexane, 0.7 mmol), benzophe-
deacti-
10:1)
oxy-methylethyl)oxazoline [(S)-6] (0.073 g, 0.2 mmol, 48%) as a
yellow liquid.
2
3
N solution in PE, 25 ꢁ 4 cm, PE/CH
2
D
ꢀ1
½aꢂ
¼ þ98 (c = 0.51, CHCl
3
). IR (ATR):
m
~ ¼ 3098 cm (w, @CH),
20
gave pure (S,pS)-B (0.170 g, 0.3 mmol, 63%, >95% de) as a yellow-
1
3
062 (w), 2976 (w), 2931 (w), 1646 (s, C@N). H NMR (400 MHz,
red solid. Recrystallization from hexane gave yellow-red crystals
CDCl
.16–4.21 (m, 1H, NCH), 4.18 (s, 5H, CpH), 4.27 (ddd, ABMX line
system, J = 9.9 Hz, 1H, OCH ), 4.32 (m, 2H, CpR), 4.43 (dd,
J = 7.1 Hz, J = 8.5 Hz, 1H, OCH ), 4.71 (m, 1H, CpR), 4.76 (m, 1H,
CpR), 5.11 (dd, ABX line system, J = 1.6 Hz, J = 10.4 Hz, 1H, @CH ),
.25 (dd, ABX line system, J = 1.7 Hz, J = 17.2 Hz, 1H, @CH ), 5.89
) ppm. C NMR (100 MHz, BB, APT, HMBC, HMQC,
):d 20.0 (–, CH ), 23.8 (–, CH ), 62.9 (+, OCH CH@), 68.4 (+,
CHN), 68.9 (–, CH-CpR), 69.0 (–, CH-CpR), 69.5 (–, CH-CpH),
0.09 (–, CH-CpR), 70.13 (–, CH-CpR) 70.5 (+, CR-CpR), 74.4
–, NCH), 76.4 [–, NCHC(CH ], 115.5 (+, @CH ), 135.8 (–, CH@CH ),
3 3 3 2
):d 1.15 (s, 3H, CH ), 1.35 (s, 3H, CH ), 3.9 (m, 2H, OCH CH@),
(
m.p. 143 °C) of (S,pS)-B. The configuration assignment is based
4
on literature precedence [4,9].
D
ꢀ1
2
½
aꢂ
¼ þ328 (c = 0.36, CHCl
m
). IR (ATR): ~
¼ 3095cm (w, OH),
2
0
3
1
2
3
076 (w, @CH), 2962 (w), 2931 (w), 2828 (w), 1650 (s, C@N).
H
2
NMR (400 MHz, CDCl
.30 (s, 3H, OCH ), 3.76 (dd, J = 1.7 Hz, 1H, CHCpR), 3.88 (dd, ABX
line system, J = 8.2 Hz, J = 9.9 Hz, 1H, NCH), 4.18 (dd, ABX line sys-
3 3 3
): d 1.29 (s, 3H, CCH ), 1.34 (s, 3H, CCH ),
5
2
3
3
1
3
(
m, 1H, CH@CH
2
3
2
3
4
CDCl
OCH
7
(
3
3
3
2
tem, J = J = 9.9 Hz, 1H, CH
2
), 4.32 (dd, J = J = 2.5 Hz, 1H, CHCpR),
2
4
.37 (s, 5H, CHCpH), 4.38 (dd, ABX line system, J = J = 8.5 Hz, 1H,
3
4
2
CH ), 4.82 (dd, J = J = 2.4 Hz, 1H, CHCpR), 7.20 (m, 5H, Ph), 7.31
3
)
2
2
2
(
m, 1H, Ph), 7.36–7.40 (m, 2H, Ph), 7.57–7.59 (m, 2H, Ph), 9.23 (s,

J.R. Garabatos-Perera, H. Butenschön / Journal of Organometallic Chemistry 694 (2009) 2047–2052
2051
1
H, OH) ppm. 13C NMR (100 MHz, BB, HMQC, HMBC, CDCl
CCH ), 22.7 (CCH ), 49.5 (OCH ), 65.6 (CRCpR), 68.0 (CHCpR), 68.3
CH ), 70.4 (CHCpR), 70.6 (CHCpH), 75.0 (CHCpR), 75.4 (COCH ), 73.7
NCH), 77.3 (COH), 101 (CRCpR), 126.2 (Ph), 126.5 (Ph), 127.0 (Ph),
27.1 (Ph), 127.3 (Ph), 127.8 (Ph), 146.3 (Ph), 149.1 (Ph), 158.4
3
): d 20.5
pure 1,1-bisferrocenylpentan-1-ol [24] (0.154 g, 0.3 mmol, 24%,
characterized crystallographically [25]) as yellow crystals and
pure (S,pR)-12 (0.564 g, 0.8 mmol, 48%, >95% de) as a yellow
foam.
(
(
(
3
3
3
2
3
D
ꢀ1
1
(S,R
P
)-12: ½
a
ꢂ
¼ þ94 (c = 0.10, CHCl
3
). IR (ATR):
m
~ ¼ 3095cm
2
0
+
+
+
1
(
[
5
OCN) ppm. MS (ESI, ES ): m/z = 492 [M –OH], 510 [M+H ], 532
(w, OH), 2958 (w), 1650 (s, C@N), 814 (s). H NMR (400 MHz,
+
3
), 1.15 (d, 3J = 6.8 Hz, 3H,
M+Na ]. HRMS (ESI) (C30
10.1732 [M+H]. C30 31FeNO
Found: C, 70.64; H, 6.09; N, 2.69%.
3
H32FeNO ): Calc.: 510.1732; found:
CDCl
CH
3 3
): d 1.09 (d, J = 6.8 Hz, 3H, CH
H
3
: Calc.: C, 70.73; H, 6.13; N, 2.75.
3
), 2.12–1.98 [m, 1H, CH(CH ], 3.88 (s, 5H, CpH), 3.89 (m, 1H,
CpR ), 3.95 (m, 1H, CpR ), 4.04 (s, 5H, CpH), 4.05 (m, 1H, CpR ),
.07 (s, 5H, CpH), 4.09 (m, 2H, 2 ꢁ CpR), 4.16 (m, 2H, 2 ꢁ CpR),
4.16 (m, ABX line system, 2H, OCH ), 4.26 (m, 1H, CpR), 4.34 (m,
ABX line system, 1H, NCH), 4.63 (m, 1H, CpR), 4.72 (m, 1H, CpR),
3 2
)
2
2
2
4
4.6. (S,pR)-2-[(2-Diphenylhydroxymethyl)ferrocenyl]-4-
2
isopropyloxazoline [(S,pR)-10]
1
3
4
.75 (m, 1H, CpR), 8.95 (s, 1H, OH) ppm. - C NMR (100 MHz,
GP1; (S)-2-ferrocenyl-4-isopropyloxazoline [(S)-9, 0.504 g,
BB, HMQC, HMBC, CDCl ): d 18.0 (CH ), 19.2 (CH ), 32.0 [CH(CH ],
3
3
3
3 2
)
1
.7 mmol], TMEDA (0.33 mL, 2.2 mmol), Et
2
O
(6.3 mL), BuLi
64.8 (CR-CpR), 65.8 (CH-CpR), 65.9 (CR-CpR), 66.2 (CH-CpR), 66.5
(CH-CpR), 66.7 (CH-CpR), 67.6 (CH-CpR), 67.8 (CH-CpR), 68.1 (CH-
CpR), 68.4 (CH-CpR), 68.5 (CH-CpH), 69.0 (CH-CpH), 69.4 (NCH),
69.9 (CH-CpR), 70.8 (CH-CpH), 72.0 (C-12), 72.2 (CH-CpR), 73.5
(CH-CpR), 100.0 (CR-CpR), 100.3 (COH), 101.1 (CR-CpR), 168.5
(
1.4 mL, 1.6 M in hexane, 2.2 mmol), benzophenone (0.309 g,
1
.7 mmol), column chromatography (SiO
2
deactivated with a 5%
Et Cl
3
N solution in PE, 25 ꢁ 4 cm, PE/CH
2
2
10:1) gave pure (S,pR)-
1
0 (0.777 g, 1.6 mmol, 96%, >95% de) as a yellow-red solid. Recrys-
tallization from hexane gave crystals of (S,pR)-10 (0.511 g,
.1 mmol, 63%, >95% de, m.p. 135 °C).
+
+
+
(NCO) ppm. MS (ESI, ES ): m/z = 678 [M –OH], 695 [M ]. HRMS
+
1
(ESI) (C37 NO
H
37Fe
3
2
): Calc.: 695.0872; found: 695.0897 [M ].
D
ꢀ1
½
aꢂ
¼ ꢀ366 (c = 0.12, CHCl
3
). IR (ATR):
OH), 3056 (w, Cp-H), 2954 (w), 2873 (w), 1650 (s, C@N).
NMR (400 MHz, CDCl
): d 0.98 (d, 3J = 6.8 Hz, 3H, CH
), 1.83–1.75 [m, 1H, CH(CH
m
~ ¼ 3514 cm
(w,
H
C
37
H
37Fe NO : Calc.: C, 63.92; H, 5.36; N, 2.01. Found: C, 64.37;
3
2
2
0
1
H, 5.57; N, 1.92%.
3
3
), 1.05 (d,
], 3.67–3.61
Jcis = 9.8 Hz,
3
J = 6.7 Hz, 3H, CH
3
3
)
2
4.8. (S,pR,R)-2-(2-Ferrocenylphenylhydroxymethylferrocenyl)-4-
isopropyloxazoline (S,pR,R)-11 and (S,pR,S)-2-(2-ferrocenylphenyl-
hydroxymethylferrocenyl)-4-isopropyl-oxazoline (S,pR,S)-11
ddd, ABMX line system, J = 6.4 Hz, 3
3
J
trans = 8.4 Hz,
3
(
1
H, NCH), 3.72 (dd, J = 1.6 Hz, J = 2.5 Hz, 1H, CpR), 3.98 (dd, ABX
3
2
line system,
system,
J
trans = Jgem = 8.3 Hz, 1H, OCH
2
), 4.17 (dd, ABX line
), 4.27 (t, J = 2.5 Hz,
2
gem = 8.4 Hz, 3Jcis = 9.8 Hz, 1H, OCH
J
2
GP1; (S)-2-ferrocenyl-4-isopropyloxazoline [(S)-9, 0.507 g,
1
H, CpR), 4.28 (s, 5H, CpH), 4.76 (dd, J = 1.6 Hz, J = 2.5 Hz, 1H,
CpR), 7.14–7.18 (m, 5H, Ph), 7.24–7.36 (m, 3H, Ph), 7.53–7.55
m, 2H, Ph), 9.3 (s, 1H, OH) ppm. 13C NMR (100 MHz, BB, DEPT,
2
1.7 mmol], TMEDA (0.3 mL, 2.2 mmol), Et O (2.5 mL), BuLi
(1.4 mL, 1.6 M in hexane, 2.2 mmol), benzoylferrocene [26]
(0.493 g, 1.7 mmol) solution in anhydrous THF (20 mL), column
(
CDCl
3
): d 18.6 (CH
7.9 (NCH), 70.0 (CpR
4.9 (CpR ), 77.2 (CpR
27.0 (Ph), 127.1 (Ph), 127.4 (Ph), 127.8 (Ph), 146.4 (Ph), 149.2
3
), 18.8 (CH
), 70.4 (CH
), 100.5 (CPh
3
), 32.4 [CH(CH
3
)
2
], 66.0 (CpR
2
),
),
chromatography (SiO
25 ꢁ 4 cm, PE/EE 9:1) gave a 3:1 or 1:3 mixture of diastereoiso-
mers (S,R ,R)-11 and (S,R ,S)-11 (0.802 g, 1.4 mmol, 80%, >95% de
) as a red oil. Recrystallization from TBME gave a 2.5:1 mixture
of diastereoisomers (0.491 g, 0.8 mmol, 49%, >95% de R ) as yellow
2
,
deactivated with Et
3
N
5% in PE,
6
7
1
2
2
), 70.6 (CpH), 71.5 (CpR
2
2
2
2
) 126.2 (Ph), 126.5 (Ph),
P
P
R
P
+
+
(
[
4
Ph), 167.5 (OCN) ppm. MS (ESI, ES ): m/z = 462 [M –OH], 480
P
+
M+H ]. HRMS (ESI) (C29
80.1606 [M+H]. C29 29FeNO
Found: C, 72.33; H, 5.95; N, 2.80%.
Crystal Structure Analysis of (S,pR)-10 : C29
2
H30FeNO ): Calc.: 480.1626; found:
crystals. The analytical data did not allow a clear cut assignment of
H
2
: Calc.: C, 72.66; H, 6.10; N, 2.92.
the diastereomers.
D
(S,pR,R)-11 and (S,R
P
,S)-11: ½
aꢂ
¼ ꢀ24 (c = 0.20, CHCl
3
). IR
2
0
ꢀ1
H
29FeNO
weight, 479.38 g mol , temperature 297 K, crystal system tetrag-
onal, space group P4 2 (No. 92), a = 11.851(3), b = 11.851(3),
c = 35.173(15) Å, = 90°, b = 90°,
2
, molecular
(ATR):
1648 (s, C@N). MS (ESI, ES ): m/z: 570 [M –OH], 588 [M+H ]. HRMS
(ESI) (C33 NO): Calc.: 570.1183; found: 570.1171 [M–OH].
33Fe : Calc.: C, 67.49; H, 5.66; N, 2.38. Found: C, 67.48;
m
~ ¼ 3095 cm (w, OH), 2961 (w), 2928 (w), 2871 (w),
ꢀ1
+ + +
1
2
1
H32Fe
2
3
a
c
= 90°, V = 4940(3) Å , Z = 8,
F(000) = 2016, Absorption coefficient =
.636 mm , crystal size 0.21 ꢁ 0.14 ꢁ 0.14 mm, Stoe IPDS area
detector diffractometer, h range = 1.81–24.24°, limiting indices
13 6 h 6 13, –13 6 k 6 13, –40 6 l 6 40, reflections collected/
unique 53815/3979 [Rint = 0.1239], completeness of data
h = 24.24): 99.5%, empirical absorption correction (multi-scan),
no extinction correction, refinement method full-matrix least-
C
33
H
2 2
NO
ꢀ3
q
0
calc = 1.289 g cm
,
H, 5.47; N, 2.13%.
ꢀ
1
1
(S,pR,R)-11 or (S,R
P
,S)-11: H NMR (400 MHz, CDCl
3
): d 0.99 (d,
3
3
J = 6.8 Hz, 3H, CH
3
), 1.10 (d, J = 6.6 Hz, 3H, CH
3
), 1.8–1.9 [m, 1H,
–
CH(CH
J = 15.9 Hz, 1H, NCH), 3.66 (s, 1H, CpR), 3.88 (m, ABX line system,
1H, OCH ), 3.90 (m, 1H, CpR), 4.04 (s, 5H, CpH), 4.06 (d, 1H,
J = 1.4 Hz, CpR), 4.10 (m, 1H, OCH ), 4.16 (dd, J = J = 2.6 Hz, 1H,
3 2
) ], 3.62 (ddd, ABMX line system, J = 6.5 Hz, J = 9.4 Hz,
(
2
2
2
2
squares on F , goodness-of-fit on F = 0.708, R
.0338 (I > 2 (I)), R-indices [all data]: R = 0.0808, wR
minimal and maximal residual electron density –0.267/0.162
1
= 0.0302, wR
2
=
CpR), 4.25 (s, 5H, CpH), 4.27 (m, 1H, CpR), 4.54 (dd, 1H,
J = 1.6 Hz, J = 2.4 Hz, CpR), 4.71 (dd, J = J = 1.1 Hz, 1H, CpR), 7.10–
0
r
1
2
= 0.0391,
7.50 (m, 4H, Ph), 7.78 (d, J = 7.2 Hz, 1H, Ph), 8.71 (s, 1H, OH)
ꢀ
3
13
eÅ
.
ppm. - C NMR (100 MHz, BB, CDCl
3
3
): d 18.6 (CH
], 65.1 [CR-CpR (CFcCOH)], 66.9 (CH-CpR), 67.0
(CH-CpR), 67.1 (CH-CpR), 67.3 (CH-CpR), 68.4 (CH-CpR), 68.8 (CH-
CpH), 69.77 (CH-CpR), 69.84 (OCH ), 70.6(CH-CpH), 71.7 (NCH),
4.12 (CH-CpR), 74.3 [CR-CpR(CFcCOH)], 96.63 (COH), 102.8 [CR-
3 3
), 19.3 (CH ),
3 2
2.4 [CH(CH )
4.7. (S,pR)-2-[2-(Diferrocenylhydroxymethyl)ferrocenyl]-4-
isopropyloxazoline (S,pR)-12
2
7
GP1; (S)-2-ferrocenyl-4-isopropyloxazoline [(S)-9] 0.503 g,
CpR(CFcCN)], 126.4 (Ph), 126.8 (Ph), 127.7 (Ph), 147.6 (Ph), 170.4
1
.7 mmol], TMEDA (0.33 mL, 2.2 mmol), Et
2
O
(6.3 mL), BuLi
(NCO) ppm.
(
(
1.4 mL, 1.6 M in hexane, 2.2 mmol), diferrocenylketone [14,15]
0.678 g, 1.7 mmol) solution in anhydrous THF (20 mL); column
(S,pR,R)-11 or (S,R
J = 6.6 Hz, 3H, CH
CH(CH
3 ꢁ 1H, CpR), 4.02 (s, 5H, CpH), 4.03 (s, 5H, CpH), 4.1–4.2 (m,
ABX line system, 2H, OCH or NCH), 4.24 (m, 1H, CpR), 4.39 (m,
P
,S)-11: 1H NMR (400 MHz, CDCl
3
): d 1.1 (d,
3
3
3
3
), 1.2 (d, J = 6.8 Hz, 3H, CH ), 1.95 [m, 1H,
chromatography (SiO
2
6
2
deactivated with Et
10:1) gave (S,R )-12 (0.718 g, 1.0 mmol,
1%, >95% de) as a red liquid. Crystallization from TBME gave
3
N
5% in PE,
3 2
) ], 3.76 (m, 1H, CpR), 3.86–3.90 (m, 1H, CpR), 4.0–4.2 (m,
5 ꢁ 4 cm, PE/CH
2
Cl
2
P
2

2
052
J.R. Garabatos-Perera, H. Butenschön / Journal of Organometallic Chemistry 694 (2009) 2047–2052
ABX line system, 1H, OCH
m, 5H, Ph), 9.6 (s, 1H, OH) ppm. C NMR (100 MHz, BB, CDCl
d 18.9 (CH ), 19.0 (CH ), 32.9 [CH(CH ], 64.6 [CR-CpR(C-18)],
5.5 (CH-CpR), 67.3 (CH-CpR), 67.9 (OCH ), 68.3 (CH-CpR), 68.8
CH-CpH), 68.9 (CH-CpR), 70.4 (NCH), 70.7 (CH-CpR), 70.8 (CH-
CpH), 72.1 (CH-CpR), 73.9 (CH-CpR), 74.5 [CR-CpR(CFcCOH)], 98.4
COH), 101.7 [CR-CpR(CFcCN)], 126.3 (Ph), 126.5 (Ph), 127.7 (Ph),
48.1 (Ph), 168.2 (COH) ppm.
2
or NCH), 4.75 (m, 1H, CpH), 7.1–7.41
Appendix A. Supplementary material
13
(
3
):
3
3
3
)
2
CCDC 709580 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
6
(
2
(
1
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4
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Acknowledgements
We thank the Deutsche Forschungsgemeinschaft for generous
support of our research. We are grateful to Octel Deutschland
GmbH and to the Max-Planck-Institut für Kohlenforschung for
donations of ferrocene.
[
[
[