Enantioselective preparation of C2-symmetrical ferrocenyl ligands for asymmetric catalysis

Article abstract of DOI:10.1002/(SICI)1521-3765(19980515)4:5<950::AID-CHEM950>3.0.CO;2-B

Corey - Bakshi - Shibata (CBS) reduction of the 1,1'-diacylmetallocenes 5 and 7 provides the C₂-symmetrical diols 4 and 10, which proved to be useful starting materials for stereo-controlled ligand synthesis. Diols 4 and 10 can be easily converted to a wide range of diamines, diphosphines, and dithioacetates by nucleophilic substitution of the hydroxyl function with full retention of configuration. Furthermore, the aminophosphines 30 and 31 become easily accessible. Compounds 30 and 31 have been used as ligands in enantioselective cross-coupling of racemic secondary Grignard reagents with vinyl bromides. A selectivity up to 93% ee could be reached for the first time in the preparation of (S)-(E)-1,3-diphenyl-1-butene (34b), which was transformed into the enantiomerically pure chiral building block 37 with a pseudoasymmetric center in a straightforward, three-step synthesis.

Full text of DOI:10.1002/(SICI)1521-3765(19980515)4:5<950::AID-CHEM950>3.0.CO;2-B

FULL PAPER
Enantioselective Preparation of C2-Symmetrical Ferrocenyl Ligands for
Asymmetric Catalysis
Lothar Schwink and Paul Knochel*
Abstract: Corey ± Bakshi ± Shibata
(CBS) reduction of the 1,1'-diacylmetal-
locenes 5 and 7 provides the C2-sym-
metrical diols 4 and 10, which proved to
be useful starting materials for stereo-
controlled ligand synthesis. Diols 4 and
10 can be easily converted to a wide
range of diamines, diphosphines, and
dithioacetates by nucleophilic substitu-
tion of the hydroxyl function with full
retention of configuration. Furthermore,
the aminophosphines 30 and 31 become
easily accessible. Compounds 30 and 31
have been used as ligands in enantiose-
lective cross-coupling of racemic secon-
dary Grignard reagents with vinyl bro-
mides. A selectivity up to 93% ee could
be reached for the first time in the
preparation of (S)-(E)-1,3-diphenyl-1-
butene (34b), which was transformed
into the enantiomerically pure chiral
building block 37 with a pseudoasym-
metric center in a straightforward, three-
step synthesis.
Keywords: asymmetric catalysis
´
chirality enantioselective cross-
´
coupling ´ sandwich complexes
´
reductions
synthesis of these ligands, we envisioned the stereocontrolled
preparation of chiral metallocenes that would open an easy
access to new ligands for asymmetric catalysis.
Introduction
In the last two decades, stereoselective synthesis and, in
particular, asymmetric catalysis have gained a great deal of
attention.[1] A major role in this field has been taken over by
transition metal complexes bearing chiral ligands. In partic-
ular, chiral cyclopentadienyl complexes of transition metals
have found widespread applications as catalysts or ligands in
enantioselective reactions.[2] The preparation of nearly all
successful structures in this field, such as the ansa-metallocene
1 introduced by Brintzinger and the ferrocenyl diphosphine
ligands 2 and 3 prepared by Hayashi and Togni, includes a
Ferrocene derivatives have recently gained renewed inter-
est for modern ligand design due to their promise for
widespread applications both on a laboratory scale and in
industry.[4] This interest is due to some exceptional features of
ferrocene chemistry, which include the replacement of
heteroatomic a-substituents with full retention of configura-
tion and the possibility of diastereoselective directed metal-
lations. The latter allows the introduction of additional
functionality and an element of planar chirality into the
ferrocenyl ligands.[4]
Herein we describe the synthesis of C2-symmetrical[5] chiral
ferrocenyl diols 4 and some of their derivatives, which lead to
a broad range of new potential ligands. A first application in
asymmetric catalysis is presented.
Results and Discussion
A retrosynthetic analysis applied to the diols 4 suggested the
diketones 5 as precursors, which, in turn, are accessible by
Friedel ± Crafts acylation of ferrocene (disconnection A,
Scheme 1) or by reaction of an appropriate organometallic
reagent with ferrocenedicarbonyl dichloride (6; disconnec-
tion B).
resolution step.[3] In order to circumvent such cumbersome
separations of enantiomers, which also limit the scope of the
[*] Prof. Dr. P. Knochel, Dr. L. Schwink
Fachbereich Chemie der Philipps-Universität Marburg
Hans-Meerwein-Strasse, D-35032 Marburg (Germany)
Fax: (‡49)6421-28-2189
Preparation of metallocenyl diketones: Acylation of ferro-
cene, one of the first reactions of a metallocene, has been
E-mail: knochel@ps1515.chemie.uni-marburg.de
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950±968
Scheme 2. Friedel ± Crafts acylation of pentamethylferrocene.
ferrocenedicarbonyl dichloride (6),[9] which also provides the
diketones 5 in good yield (Scheme 3). This reaction should be
useful if the required acid chlorides are unavailable or
unstable.
Scheme 1. Retrosynthetic analysis of the ferrocenyl diols 4.
known since 1952.[6] The reaction can be controlled by a
proper choice of the stoichiometry and the mode of addition
to give either the mono- or diacylated products quite cleanly.
Addition of ferrocene to a complex of AlCl3 and an acid
chloride (1:1 ratio, 2 equiv) in dichloromethane provides the
1,1'-diketones 5 in good yield. The reaction works equally well
for alkyl and aryl substituents R. Several additional function-
alities, like esters, ethers, and halogen atoms, are tolerated
(Table 1, entries 1 ± 14).
Scheme 3. An alternative to Friedel ± Crafts acylation: the reaction of
Table 1. Friedel-Crafts acylation of metallocenes.
zinc ± copper reagents with 6 also provides diketones 5 in good yield.
CBS reduction of metallocenyl ketones: For the asymmetric
reduction of the metallocenyl ketones 5, 7, and 8, the
procedure developed by Corey and Itsuno was chosen
because it had showed its broad utility during the last
decade.[10] Previous attempts to reduce metallocenyl ketones
enantioselectively were either restricted to monoacylated
systems or led to diols with only poor optical purity.[11] Other
methods for the enantioselective preparation of a-chiral
ferrocenyl alcohols employed the addition of dialkylzincs to
ferrocene aldehydes[12] or used a tedious enzymatic resolu-
tion.[13]
Our approach allows the easy preparation of nearly
enantiomerically pure C2-symmetrical ferrocenyl diols 4
contaminated with only small amounts of the meso diaster-
eomers.[14] Thus, the reduction of 1,1'-diacetylferrocene (5a)
can be performed with 60 mol% of the oxazaborolidine 9 and
2 equiv of BH3 ´ SMe2 in THFat 08C (0.5 h) providing a nearly
quantitative yield of the diol 4a with a diastereomeric ratio
dl:meso of 98.5:1.5. The optical purity found by chiral HPLC
was >99% ee (Table 2, entry 1).
Entry
Diketone 5 or 7
M
R
Yield [%]
1
2
3
4
5
6
7
8
5a
5b
5c
5d
5e
5 f
5g
5h
5i
5j
5k
5l
5m
5n
7a
7b
7c
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Fe
Ru
Ru
Ru
Me
Me, Pent
Pent
(CH2)3Cl
(CH2)2CO2Me
iPr
cHex
tBu
Ph
o-Tol
p-MeOC6H4
p-FC6H4
1-naphthyl
2-naphthyl
Me
85
85[a]
92
61
40
75
80
26
82
73
64
67
72
35
34
47
50
9
10
11
12
13
14
15
16
17
Pent
Ph
The situation changes only slightly for the reduction of the
diketones 5 bearing higher alkyl chains. If R is ethyl or pentyl,
a diastereoselectivity of ca. 88:12 is observed (entries 2 and 4).
Ester- or chloro-functionalized alkyl chains do not disturb the
reduction. The results with these substituents are even better
than for the simple alkyl chains (entries 6 ± 8).
A further increase in the steric bulk of R, for example, in an
isopropyl or cyclohexyl group, leads to a decrease of the
dl:meso ratio (85:15 and 80:20, respectively; entries 9 and 11).
In such cases the result can be significantly improved by use of
a stoichiometric amount (200 mol%) of the catalyst 9
(entries 5 and 10). Interestingly, even those diols that only
show a diastereomeric excess of around 74% (dl:meso ˆ
[a] Acetylferrocene was acylated with hexanoyl chloride.
Non C2-symmetrical diketones are obtained by sequential
acylation with two different acid chlorides (entry 2). Ruth-
enocene is less reactive in Friedel ± Crafts acylation[7] and only
moderate yields of the diketones 7 could be obtained
(entries 15 ± 17). The reaction could also be extended to
pentamethylferrocene for the first time, although the yield of
the resulting ketones 8a,b was again significantly lower than
in the ferrocene case (Scheme 2).
An alternative to the Friedel ± Crafts acylation was found in
the reaction of (functionalized) zinc ± copper reagents[8] with
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P. Knochel, L. Schwink
FULL PAPER
Table 2. CBS reduction of the diacetylmetallocenes 5 and 7 to yield the
diols 4 and 10.
The separation of the meso diastereomers from the desired
C2-symmetrical diols 4 is difficult and generally cannot be
done by simple column chromatography. Recrystallization of
alkyl-substituted diols 4 must be repeated quite often or is
described to be ineffective.[16] We found that diols with
aromatic substituents can be purified by recrystallization
yielding nearly diastereomerically pure compounds (en-
tries 13 and 18). In other cases, the meso diastereomer can
be separated during later stages of ligand synthesis (see below
and experimental procedure).
Thus, a wide variety of nearly enantiomerically pure diols 4
can be conveniently prepared from the corresponding dike-
tones 5 by enantioselective reduction with good to excellent
optical and chemical yields.
This statement also holds for the reduction of the analogous
ruthenocenyl diketones 7 to the ruthenocenyl diols 9 (en-
tries18 ± 20). Remarkably, the reduction of 1,1'-diacetylruthe-
nocene (7a) is far less selective (dl:meso ˆ 87:13) than that of
1,1'-diacetylferrocene (5a), which gives dl:meso ˆ 98.5:1.5
(compare entries 1 and 18). On the other hand, for substitu-
ents like pentyl or phenyl no significant decrease is observed
on changing the central metal from iron to ruthenium
(compare entries 4 and 13 with 20 and 21).
Entry
R
9
Diol
Yield
dl:meso
ee
[mol %] 4 or 10 [%]
[%][a]
1
2
3
4
5
6
7
8
Me
Et
Me, Pent
Pent
Pent
(CH2)3Cl
(CH2)3OPiv
(CH2)2CO2Me
iPr
iPr
cHex
tBu
Ph
oTol
p-MeO-C6H4
p-F-C6H4
1-naphthyl
2-naphthyl
Me
60
60
60
60
200
60
60
60
60
200
60
60
60
60
60
60
60
60
60
60
60
4 a
4 b
4 c
4 d
4 d
4 e
4 f
4 g
4 h
4 h
4 i
4 j
4 k
4 l
4 m
4 n
4 o
4 p
10 a
10 b
10 c
98
97
94
98
98
91
82
84
91
91
98
99
89
94
58
94
74
80
74
87
92
98.5 : 1.5 > 99
88 : 12
95 : 5
87 : 13
92 : 8
94 : 6
89 : 11
95 : 5
85 : 15
94 : 6
80 : 20
51 : 49
94 : 6[b] (>99)
95 : 5
92 : 8
90 : 10 (>99)
94 : 6 (>99)
86 : 14[c] (99)
87 : 13
85 : 15
95 : 5
99.8
(>99)
99
> 99
(>99)
> 99
(>99)
98.9
> 99
97.6
±
9
10
11
12
13
14
15
16
17
18
19
20
21
(>99)
(>99)
Extension of the method to the heteroleptic ferrocenyl
ketones 8a,b was possible without problems and afforded the
corresponding chiral alcohols 11a and 11b with >95% and
94% ee, respectively (Scheme 4).
(99)
(99)
(>99)
Pent
Ph
[a] Determined by chiral HPLC; values in parentheses are enantiomeric
purities of derived products. [b] Repeated crystallization from MTBE gave
dl:meso ˆ >98: < 2. [c] Single crystallization from THF gave dl:meso ˆ
97:3.
87:13) were found to be nearly enantiomerically pure (>99%
ee). This outcome is predicted by the Horeau principle, which
is valid for the combination of two (or more) independent
stereocenters in one molecule.[15] Thus, the assumption that
the second reduction in the diketones 5 is not largely affected
by the stereocenter already established seems to be justified.
If a quaternary center is attached to the carbonyl group
(e.g., in diketone 5h) the CBS reduction becomes very slow
even at room temperature and is unselective (entry 12).
In summary, an increase in the steric demand of R leads to a
lowering of the selectivity of the reduction (Figure 1).
Scheme 4. Synthesis of chiral alcohols 11a and 11b from heteroleptic
ferrocenyl ketones 8a,b.
The newly accessible optically active a-chiral metallocenyl
alcohols 4, 10, and 11 are the basis of the further trans-
formations described below.
Formation of acetates and substitution by heteroatom nucle-
ophiles: Since the pioneering work of Ugi in 1970 it is well
documented that hydroxyl groups in a-position to a ferrocenyl
moiety can be substituted with full retention of configuration
by a broad range of heteroatom-centered nucleophiles.[17] We
found that this reaction can be extended to 1,1'-disubstituted
C2-symmetrical systems.
In a first step, the diols 4 and 10 are quantitatively
converted to the corresponding diacetates 12 and 13 by
treatment with acetic anhydride in pyridine. Removal of the
volatiles in vacuum provides 12 and 13 as pure materials
without the need for further purification. They can be used in
the same reaction vessel for the reaction with the nucleophile.
Only the sterically hindered, isopropyl-substituted diol 4h
Figure 1. Selectivity vs. steric demand of substituent R in the reduction of
metallocenyl diketones 5.
Beside the alkyl groups R discussed so far, various aryl
moieties work equally well (entries 13 ± 18). Even an ortho
substituent in the aromatic ring is tolerated without loss of
selectivity (entries 14 and 17).
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c2-Symmetrical Ferrocenyl Ligands
950±968
Table 3. Conversion of the metallocenyl diols 4 and 5 to the diamines 17 and 18
by double substitution.
needs more forcing conditions (Ac2O, AcCl, DMAP, pyridine)
for full conversion to the diacetate 12e.
In the second step, substitution of the acetates is accom-
plished under mild solvolytic conditions using an excess of the
nucleophile (Scheme 5).
Entry Solvent
R
Amine Yield dl:meso dl:meso
17, 18 [%]
Retention
[%][a]
1
2
3
4
5
MeOH/H2O Me
MeOH/H2O Pent
17 a
17 b
17 c
91
90
94
85
93
98 : 2
89 : 11 [b] 92 : 8
91 : 9 94 : 6
82 : 18[c] 86 : 14
93 : 7 95 : 5
98.5 : 1.5 > 98
> 98
THF/H2O
THF/H2O
THF/H2O
Ph
> 98
> 98
> 97
2-naphthyl 17 d
Ph 18
Scheme 5. General reaction scheme for the two-step one-pot substitution
of the hydroxyl funtions in C2-symmetrical metallocenyl diols 4 and 10 with
nucleophiles.
[a] Calculated as retention at one stereogenic center. [b] Diastereomerically pure
after chromatography. [c] The ratio dl:meso was 95:5 after recrystallization.
Table 4. Conversion of the metallocenyl diols 4 and 10 to the secondary
diamines 19 and 20.
The solvent system THF/H2O is appropriate for the more
reactive aryl-substituted acetates, while alkyl-substituted
acetates react only in a more polar mixture of methanol and
water. The choice of the reaction medium is crucial, as can be
seen from the reaction of acetate 14 with dimethylamine in
THF/H2O, which gives the desired amine 15 quantitatively.[18]
When the reactive acetate 14 is treated with dimethylamine in
MeOH/H2O only the undesired methoxy-substituted product
16 can be isolated (Scheme 6).
Entry
M
R
R'
Diamine
19 or 20
Yield
[%]
dl : meso [a]
1
2
3
4
5
6
7
Fe
Fe
Fe
Ru
Fe
Fe
Fe
Me
iPr
Ph
Ph
Me
Ph
Me
Me
Me
Me
Bn
Bn
Ph
19 a
19 b
19 c
20
19 d
19 e
19 f
95 [b] > 98 : 2
20
71
64
78
86
90
> 99 : 1
92 : 8
95 : 5
> 97 : 3
> 98 : 2
> 98 : 2
Me
[a] After chromatographic purification. [b] Yield of the crude diamine.
identified in some cases as minor by-products. They may be
formed by an internal Sn2-like attack of the amino function
introduced in the first substitution on the remaining acetate.
The stereochemical inversion in the intramolecular process
causes symmetrization. Consequently, the meso-amines 21 are
obtained. The reaction with methylamine (R' ˆ Me) is reliable
for different substituents R (Table 4, entries 1, 3 ± 4), although
yields are moderate to low if steric hindrance becomes
important (entry 2).
Other alkyl amines, like benzylamine (entries 5 ± 6), are
also suitable, as well as aniline (entry 7). In contrast to the
tertiary diamines 17 and 18 the diastereomeric ratio of the
crude secondary diamines 19 and 20 is often easily improved
by simple column chromatography.
Scheme 6. Illustration of the strong influence of the reaction medium on
the product of substitution reactions with ferrocenyl acetates.
Nevertheless, with a proper choice of solvent the reaction of
all acetates with aqueous dimethylamine is clean and there-
fore suitable for determining the stereochemical course of the
reaction by NMR analysis of the crude product (Table 3).
Observation of only a slight change in the diastereomeric ratio
on transformation of the diols 4 to the diamines 17 indicates
that the substitutions proceed with >98% retention at one
center (entries 1 ± 4). This result is in accord with the reported
value for a single substitution.[19] Also, no substantial loss of
stereochemical information was detected during the conver-
sion of the ruthenocenyl diol 10c to the corresponding
diamine 18 (entry 5).
Debenzylation of the compounds 19d,e affords the primary
diamines 22a,b in essentially quantitative yield (Scheme 7).
Thus, chiral ferrocenyl diamines with all substitution patterns
on nitrogen are now easily accessible.[20] Ligands with nitrogen
donors attract considerable interest for transition metal
Primary amines react in the same manner with the
diacetates 12 and 13 to yield the secondary diamines 19 and
20 (Table 4). The optically inactive cyclic amines 21 were
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Scheme 7. Primary diamines 22a,b are obtained in essentially quantitative
yield from debenzylation of the compounds 19d,e.
catalyzed reactions because they show several beneficial
properties compared with those of the classical diphosphines,
especially as far as synthesis is concerned.[21] For example, we
found that the secondary diamines 19 and 20 are good ligands
for the ruthenium-catalyzed transfer hydrogenation of ketones.[22]
As mentioned above, the CBS reduction of acylmetallo-
cenes allows the facile preparation of metallocenyl diols with
additional functionality. This can be used to synthesize new
types of ferrocenyl ligands. Thus, the chloro-functionalized
diol 4e was cyclized to give the bis(tetrahydrofuranyl)
derivative 23 by simple treatment with nBuLi in THF
(Scheme 8). Ligand 23 may act as a chiral complexation
agent for various kinds of metal centers.
Scheme 9. Synthesis of the ferocenyl pyrrolidinones 24 and pyrrolidines 25
and 26 from the diols 4g,e.
Scheme 8. Cyclization of diol 4e to give the bis(tetrahydrofuranyl)
derivative 23.
Aza-heterocycles are obtained directly when treating the
acetates of the diols 4e and 4g with primary amines
(Scheme 9). The ester-functionalized diol 4g is transformed
to the dipyrrolidinones 24 in variable yields, while the chloro-
functionalized diol 4e affords the dipyrrolidines 25.
The dipyrrolidines 25 can also be obtained indirectly from
the dipyrrolidinones 24 by LiAlH4 reduction. Debenzylation
of 25b gives access to the N-unsubstituted dipyrrolidine 26 in
nearly quantitative yield.
Scheme 10. Substitution of metallocenyl diacetates by phosphorus and
sulfur nucleophiles in acetic acid as reaction media leading to the
diphosphines 27 ± 28 and the dithioacetate 29.
In the same way as the diphosphines, the dithioacetate 29
was obtained in nearly quantitative yield with KSAc as
nucleophile. The dithioacetate 29 may serve as starting
material for further ligand synthesis, for example, with respect
to asymmetric copper-catalyzed reactions.
In conclusion, the diols 4 and 10 proved to be a rich source
for one- or two-step synthesis of 1,1'-disubstituted a-chiral
metallocenes bearing nitrogen, phosphorus, or sulfur donor
atoms, which may serve as chiral ligands in a wide range of
transition metal catalyzed reactions.
Phosphorous and sulfur nucleophiles: It has been shown by
Hayashi and Togni that a-substitutions of ferrocenyl acetates
by phosphorus and sulfur nucleophiles can be effected in
acetic acid as reaction media.[23] We have investigated this
reaction for the preparation of diphosphines and dithioace-
tates (Scheme 10). Thus, the diols 4h and 10c were acylated
and allowed to react with an excess of diphenylphosphine in
acetic acid at 508C for 3 h. The resulting diarylalkylphos-
phines are sensitive to oxygen and were therefore protected
with borane after changing the solvent from acetic acid to
THF. The borane-protected diphosphines 27 and 28 can be
isolated very conveniently by standard workup and purifica-
tion procedures.[24] After deprotection, 27 and 28 may be used
as ligands for transition metal catalyzed hydrogenation.
Conformational fixation of a-chiral metallocenes: Besides the
facile substitution in the a-position there is a second very
valuable reaction that is characteristic of ferrocenyl com-
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c2-Symmetrical Ferrocenyl Ligands
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pounds: the directed diastereoselective ortho-metallation of
a-(N,N-dimethylamino)alkylferrocenes. Ugi found that the
protons H2 and H5 of (R)-a-(N,N-dimethylamino)ethylferro-
cene are abstracted by nBuLi with a selectivity of 96:4
(Scheme 11).[25]
for one rotamer is much smaller for the following C ± C bond,
which connects C7 and C8. NOEs must be assigned to two
conformations (A and B) and more equilibrated J coupling
constants were observed. The third conformation C is avoided
because of unfavorable syn-pentane interactions (Scheme 12).
In conclusion, the bulky ferrocenyl moiety together with a
large a-substituent is a good anchor that is capable of fixing
conformations in acyclic systems. Control over 2 ± 3 bonds is
reached and may be used to arrange functionalities along this
region.
3
Scheme 11. Ugiꢁs abstraction of H2 and H5 of (R)-a-(N,N-dimethylami-
no)ethylferrocene.
Double directed diastereoselective ortho-metallation: As
mentioned above, the best known application of the stereo-
chemical fixation of a-dimethylamino-substituted ferrocenes
is the directed diastereoselective ortho-metallation. As a
consequence, we tried to apply this reaction to the diamines
17 and 18, which became easily available by the work
described above. Thus, double deprotonation of the amines
17 could be effected by reaction with 3 ± 5 equiv of nBuLi in
diethyl ether for several hours at room temperature. In the
case of the pentyl-substituted diamine 17b, tBuLi was
required to obtain efficient metallation. Reaction of the
resulting dilithio-species with chlorodiphenylphosphine pro-
vides the C2-symmetrical aminophosphine 30, obtained in
moderate yield as diastereomerically and nearly enantiomeri-
cally pure after chromatography (Table 5).[28]
In order to support the simple explanation that steric
repulsion puts both the dimethylamino and the alkyl group
above the ring plane and
therefore adjusts the nitrogen
as complexation site for nBuLi
near to H2, we performed an
NOE experiment with the C2-
symmetrical diamine 17b (Fig-
ure 2). Because the signals of
the protons H2 and H5 were
Figure 2. Preferred confor-
not sufficiently separated, they
were distinguished by a 13C
edited NOE experiment.[26]
The results confirm the picture
drawn by Ugi with the modifi-
cation that the alkyl chain
mation of (R)-a-(N,N-dime-
thylamino)alkylferrocenes
deduced from 13C edited
NOE measurements of dia-
mine 17b (R ˆ Bu).
Table 5. Conversion of the diamines 17 and 18 to the aminophosphines 30
and 31.
seems to lie in or only slightly above the ring plane as
indicated by the fact that the proton H6 does not show an
NOE with H5 while strong interaction with H2 is observed.
This conclusion is in accord with a report by Butler, who
performed similar measurements but had to use a somewhat
perturbed model system to get the required signal separa-
tion.[27]
Conformational fixation of 17b is not limited to the rotation
about the C1 ± C6-bond but can also be seen for the C6 ± C7-
bond. Only NOEs belonging to the set of rotamers shown in
Scheme 12 were observed. The conformation depicted is
Entry
R
Base
Diphosphine Yield [%] ee [%]
30 or 31
1
2
3
4
5
Me
Pent
Ph
2-naphthyl
Ph
nBuLi
tBuLi
nBuLi
nBuLi
nBuLi
30a
30b
30c
30d
31
29
39
57
31
43
> 98
> 98
> 98
> 98
> 98
The major reason for the moderate yield is the formation of
substantial amounts of the monophosphorylated diamines,
although excess BuLi was always used for metallation.
The reaction sequence can also be applied to the rutheno-
cenyl diamine 18 to provide the diphosphines 31 with a larger
bite angle compared with the structures 30.[29]
Asymmetric cross-coupling: The aminophosphines 30 and 31
Scheme 12. Conformations of the C6-C7-C8 region of the diamine 17b
(R ˆ Bu).
react quantitatively with
a stoichiometric amount of
Pd(MeCN)2Cl2 in toluene. However, only the phenyl-substi-
tuted ligand 30c gave the expected C2-symmetrical complex
32c cleanly, as indicated by NMR analysis (Scheme 13). In all
other cases, the reaction products turned out to be mixtures,
supported by the values of the coupling constants of the
methine proton H6, which differ markedly and suggest a trans-
relation between H6 and H7b (3J6,7b ˆ 10.9 Hz). The preference
Chem. Eur. J. 1998, 4, No. 5
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955

P. Knochel, L. Schwink
FULL PAPER
Hayashi has already reported the preparation and use of
the aminophosphine 30a and its palladium complex 32a for
asymmetric cross-coupling eight years ago.[34] However, since
very tedious resolution and separation procedures were
necessary to obtain the pure ligand, further development
was strongly hampered. Our approach allows the facile
construction of the aminophosphines 30 and 31, avoiding the
need to search for good resolution procedures for every new
substituent R. Variations can now be done easily in a flexible
and predictable manner. Optimization of the ligand structure
in a short time becomes possible by a simple trial and error
approach.
Scheme 13. Reaction of aminophosphines 30 and 31 with Pd(MeCN)2Cl2
in toluene; only 30c gives the expected C2-symmetrical complex 32c
cleanly.
Attempted extension of the asymmetric cross-coupling to
other vinyl bromides and the use of sBuMgCl as coupling
reagent with the palladium complex 32c were generally
unsuccessful. Only the reaction of 1-phenylethylmagnesium
chloride with 1-bromo-1-propene gave a satisfactory selectiv-
ity of 65% ee (Scheme 14, compound 34c).
which seem to be at least partially less symmetrical coordi-
nation isomers as previously observed in similar complexation
reactions of other P,N-ligands.[30]
The palladium complexes 32 and 33 were found to catalyze
the asymmetric cross-coupling of 1-phenylethylmagnesium
chloride with vinyl bromide and b-bromostyrene under the
standard conditions reported by Hayashi (Table 6).[31] In the
Table 6. Asymmetric cross-coupling of 1-phenylethylmagnesium chloride
with vinyl bromide or b-bromostyrene catalyzed by the palladium
complexes 32 and 33.
Entry R'
Pd-complex
32 or 33
R
Yield [%] ee [%]
Additive
Scheme 14. Cross-coupling products 34c ± h obtained from the reaction of
1-phenylethylmagnesium chloride or sec-butylmagnesium chloride with
different vinyl bromides and palladium complex 32c as catalyst.
1
2
3
4
5
H
H
H
H
H
H
32 b
32 c
32 d
33
32 c
32 c
Pent
Ph
2-naphthyl 84
Ph
Ph
82
81
64
63
63
68
76
82
68
80
93
29
±
±
±
±
The use of a larger alkenyl bromide like (E)-1-bromo-5-
chloro-1-pentene gave a product of low optical purity (34d).
Introduction of a methyl group into the a-position of b-
bromostyrene caused a drop in the selectivity from 93 to 59%
ee (34e), which was also accompanied by a reduced yield due
to the formation of the homocoupling product of the vinyl
bromide. A methyl group in a geminal position to the vinylic
bromide, as found in 2-bromo-1-propene, causes a total loss of
selectivity. Furthermore, the proton trans to the bromide
makes this starting material sensitive to elimination of
hydrobromic acid by the basic Grignard reagent, which
explains the poor yield of 33% (34 f).
The exchange of 1-phenylethylmagnesium chloride for sec-
butylmagnesium chloride resulted in the formation of vir-
tually racemic products in all cases, although the yields were
quite reasonable (compounds 34g,h).
In conclusion, asymmetric cross-coupling of racemic
Grignard reagents is still limited to very few good examples.
Nevertheless our work now allows the preparation of (S)-(E)-
1,3-diphenyl-1-butene (34b) with 93% ee by this method.
With optically active 34b in hand we sought an application
in asymmetric synthesis that uses the double bond for further
elaboration. Thus, 34b can be stereoselectively dihydroxy-
lated according to the Sharpless procedure in 85% yield to
82
88
86
73
78
89
82
ZnCl2
Znl2
±
±
6
Ph
7
8
9
10
Ph 32 a
Ph 32 b
Ph 32 c
Ph 32 c
Me
Pent
Ph
±
Ph
ZnCl2
reactions of vinyl bromide (R' ˆ H), the enantiomeric excess
of the resulting 3-phenyl-1-butene (34a) was around 65% and
independent of the exact nature of the substituent R in the
ligand (entries 1 ± 4). This result was improved to 76 and 82%
ee by addition of two equivalents of zinc chloride and zinc
iodide, respectively, to the Grignard reagent (entries 5 and
6).[32]
A different situation was found when cross-coupling was
tried with b-bromostyrene. The optical purity of product 34b
increased significantly from 68% to 80% and 93% ee on
changing the substituent R in the ligand from methyl to pentyl
and phenyl (entries 7 ± 9). The last result compares well with
the highest value of 73% ee reported so far for this specific
reaction.[33] Contrary to the coupling of vinyl bromide the
addition of zinc chloride to the reaction mixture had a
negative effect on the optical purity of 34b (entry 10).
956
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Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
provide the diol 35 as a 90:10 mixture of diastereomers.[35]
A
Experimental Section
two-step, one-pot dehydration allows the isolation of the
epoxide 36 in 78% yield.[36] This epoxide can be opened by
MeCu(CN)Li in a regioselective and stereospecific manner to
give the pseudo-C2-symmetrical alcohol 37.[37] This new chiral
building block is obtained diastereomerically pure in 68%
yield and >99% ee after chromatography (Scheme 15).
General: Melting points are uncorrected. NMR spectra were recorded at
room temperature in CDCl3 on Bruker ARX200, AC300, AM400, or
AMX500 instruments. Chemical shifts are given relative to the residual
solvent peak (d). Signals of the meso diastereomer that appear separated
from the dl isomer are given for sake of comparison even in such cases in
which the isolation of the pure dl isomer was possible. Optical rotations
were measured on a Perkin ± Elmer 241 polarimeter. IR spectra were
recorded on a Nicolet 510 FT-IR-spectrometer. Electron impact (EI) mass
spectra were recorded on Varian CH7A. Enantiomeric excesses were
determined by HPLC. A Chiralcel OD column (Daicel Chemical Indus-
tries) was used at room temperature with n-heptane/2-propanol as mobile
phase and detection by a diode array UV/Vis detector. Alternatively,
determination of optical purity was carried out by GC on a Chirasil-DEX
CB column (Chrompak) with hydrogen as carrier gas. Racemic compounds
were used to choose the operating conditions for the resolution of the
enantiomer and diastereomer peaks. Ether in workup procedures refers to
tert-butyl methyl ether (MTBE). Organic layers were dried over anhydrous
MgSO4. Column chromatography was carried out on silica gel 60 (70 ±
230 mesh ASTM).
Materials: THF was distilled from potassium, Et2O was distilled from
sodium, CH2Cl2 was distilled from CaH2. Pyridine was dried over KOH.
Commercial reagents were used without further purification. The following
starting materials were prepared according to literature procedures:
pentamethylferrocene,[38] ruthenocene,[39] acetylferrocene,[40] 1,1'-ferroce-
nedicarbonyl dichloride (6),[9] (E)-1-bromo-2-phenyl-1-propene,[41] and 1-
phenylethylmagnesium chloride.[42] Lithium chloride was dried for 3 h at
1408C in vacuum (0.7 mmHg). Pd(OH)2 (10% on C) was dried for 3 d at
808C in vacuum. A 1m solution of BH3 ´ SMe2 in THF was prepared from
commercial BH3 ´ SMe2 (10m) directly before use.
Scheme 15. Conversion of the cross-coupling product 34b to the enantio-
merically pure chiral building block 37.
A combination of the newly introduced ligand 32c for
palladium catalyzed asymmetric cross-coupling and the now
well established asymmetric dihydroxylation chemistry made
it therefore possible to synthesize the chiral building block 37
as a single enantiomer that may find applications in the
preparation of a new class of chiral ligands with pseudoasym-
metric centers.
General procedure A for diacylmetallocenes 5 and 7 by Friedel ± Crafts
acylation: The acid chloride (22.5 mmol) was added to a suspension of
aluminum(iii) chloride (2.65 g, 20.0 mmol) in CH2Cl2 (10 mL) at 08C. The
metallocene (8.10 mmol) in CH2Cl2 (10 mL) was added dropwise within
20 min. The reaction was warmed to room temperature and stirred for 2 h.
Hydrolysis was done at 08C by dropwise addition of ice-cold water (50 mL;
caution: gas evolution!). The reaction mixture was diluted with CH2Cl2
(100 mL) and washed twice with saturated aqueous K2CO3 (50 mL) and
brine (50 mL). The organic layer was dried and concentrated to afford an
oil, which was purified by column chromatography.
1,1'-Diacetylferrocene (5a): From ferrocene (1.50 g, 8.10 mmol), acetyl
chloride (1.6 mL, 22.5 mmol), and aluminum(iii) chloride (2.65 g,
20.0 mmol) a yield of 85% (1.87 g) was obtained after chromatography
(hexanes/MTBE 1:1). Brown ± red solid; m.p. 122 ± 1248C; IR (KBr):
nÄmax ˆ 3104 (w), 3089 (w), 3074 (w), 1660 (vs), 1456 (s), 1375 (s), 1279 (s),
1116 (m), 844 (w); 1H NMR (CDCl3, 200 MHz): d ˆ 4.73 ± 4.72 (m, 4H),
4.47 ± 4.46 (m, 4H), 2.31 (s, 6H); 13C NMR (CDCl3, 50 MHz): d ˆ 201.01,
Conclusion
A highly flexible, efficient and enantioselective synthetic
route to (nearly) enantiomerically pure C2-symmetrical a-
chiral metallocenyl diols 4 and 10 relying on the CBS
reduction protocol was developed. The diols can be easily
substituted with retention of configuration under very mild
solvolytic conditions by various heteroatom-centered nucle-
ophiles. A broad range of diamines (17 ± 20, 22) with all kinds
of substitution patterns is accessible, along with some
diphosphines (27, 28) and the dithioacetate 29.
These structures open the way to multiple uses as chiral
ligands for transition metal catalyzed reactions. For an initial
example, the diamines 17 and 18 were converted to the
aminophosphines 30 and 31 by diastereoselective directed
ortho-metallation and subsequent reaction with chlorodiphe-
nylphosphine. The palladium complex of 30c catalyzed the
asymmetric cross-coupling of 1-phenylethylmagnesium chlor-
ide and b-bromostyrene providing (S)-1,3-diphenyl-1-butene
(34b) with 93% ee. This cross-coupling product was converted
to the enantiomerically pure (>99% ee) chiral building block
37 with a pseudoasymmetric center in a straightforward 3-step
synthesis. Further applications of the new C2-symmetrical
ferrocenyl ligands are under investigation.
‡
80.55, 73.49, 70.85, 27.54; MS (EI, 70 eV): m/z (%): 270 (M , 100), 255 (8),
227 (12), 199 (24), 163 (13), 121 (11); C14H14FeO2 (270.11): calcd C 62.25, H
5.22; found C 62.42, H 5.29.
1-Acetyl-1'-hexanoylferrocene (5b): From acetylferrocene (0.75 g,
3.30 mmol), hexanoyl chloride (603 mg, 4.30 mmol) and aluminum(iii)
chloride (1.1 g, 8.3 mmol) a yield of 85% (924 mg) was obtained after
chromatography (hexanes/MTBE 3:1). Deep red solid; m.p. 56 ± 578C; IR
(KBr): nÄmax ˆ 3091 (w), 2952 (m), 2929 (m), 2869 (m), 1656 (vs), 1456 (s),
1373 (m), 1281 (m), 841 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.63 (t, J ˆ
1.8 Hz, 2H), 4.61 (t, J ˆ 1.8 Hz, 2H), 4.35 ± 4.34 (m, 4H), 2.50 (t, J ˆ 7.5 Hz,
2H), 2.21 (s, 3H), 1.57 ± 1.51 (m, 2H), 1.24 ± 1.19 (m, 4H), 0.79 (t, J ˆ 7.5 Hz,
3H); 13C NMR (CDCl3, 75 MHz): d ˆ 203.07, 200.58, 80.34, 80.30, 73.16,
73.05, 70.37, 39.55, 31.28, 27.27, 23.60, 22.23, 13.68; MS (EI, 70 eV): m/z (%):
‡
326 (M , 100), 270 (15), 255 (14), 199 (21), 163 (6), 148 (3), 121 (19);
C18H22FeO2 (326.22): calcd C 66.27, H 6.80; found C 66.30, H 6.78.
1,1'-Dihexanoylferrocene (5c): From ferrocene (1.11 g, 6.00 mmol), hex-
anoyl chloride (2.7 g, 20.0 mmol) and aluminum(iii) chloride (2.4 g,
18.0 mmol) a yield of 92% (2.12 g) was obtained after chromatography
(hexanes/MTBE 8:1). Red solid; m.p. 44 ± 458C; IR (KBr): nÄmax ˆ 3095 (w),
2956 (m), 2928 (s), 2860 (w), 1679 (vs), 1463 (m), 1372 (w), 1258 (m), 1219
(m), 824 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 4.61 ± 4.59 (m, 4H), 4.32 ±
4.30 (m, 4H), 2.49 (t, J ˆ 7.3 Hz, 4H), 1.55 ± 1.51 (m, 4H), 1.23 ± 1.20 (m,
Chem. Eur. J. 1998, 4, No. 5
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957

P. Knochel, L. Schwink
FULL PAPER
8H), 0.77 (t, J ˆ 6.0 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 203.30,
(hexanes/MTBE 3:1). Red solid; m.p. 124 ± 1258C; IR (KBr): nÄmax ˆ 3085
(w), 2923 (w), 1647 (vs), 1443 (m), 1273 (s), 840 (m), 737 (s); 1H NMR
(CDCl3, 200 MHz): d ˆ 7.50 ± 7.24 (m, 8H), 4.84 (t, J ˆ 1.9 Hz, 4H), 4.67 (t,
J ˆ 1.9 Hz, 4H), 2.34 (s, 6H); 13C NMR (CDCl3, 50 MHz): d ˆ 200.78,
138.92, 136.13, 131.14, 130.13, 127.71, 124.97, 80.49, 74.09, 72.44, 19.70; MS
80.10, 73.00, 70.25, 39.50, 31.26, 23.62, 22.21, 13.64; MS (EI, 70 eV): m/z
‡
(%): 382 (M , 100), 326 (7), 311 (7), 186 (15), 121 (19); C22H30FeO2
(382.33): calcd C 69.11, H 7.91; found C 69.11, H 8.06.
1,1'-Bis(d-chlorobutanoyl)ferrocene (5d): From ferrocene (1.11 g,
6.00 mmol), 4-chlorobutanoyl chloride (2.8 g, 20.0 mmol), and aluminu-
m(iii) chloride (2.4 g, 18.0 mmol) a yield of 61% (1.45 g) was obtained after
chromatography (hexanes/MTBE 3:1). Red solid; m.p. 818C; IR (KBr):
nÄmax ˆ 3099 (w), 3083 (w), 2924 (m), 1663 (vs), 1459 (m), 1252 (m), 818 (m);
1H NMR (CDCl3, 200 MHz): d ˆ 4.78 (s, 4H), 4.49 (s, 4H), 3.66 (t, J ˆ
6.1 Hz, 4H), 2.84 (t, J ˆ 6.8 Hz, 4H), 2.14 (quin, J ˆ 6.2 Hz, 4H); 13C NMR
(CDCl3, 75 MHz): d ˆ 202.12, 79.97, 73.48, 70.51, 44.65, 36.14, 26.35; MS
‡
(EI, 70 eV): m/z (%): 422 (M , 100), 303 (16), 212 (9), 119 (18), 91 (63);
C26H22FeO2 (422.31): calcd C 73.95, H 5.25; found C 74.01, H 5.34.
1,1'-Bis(p-methoxybenzoyl)ferrocene (5k): From ferrocene (5.60 g,
30.0 mmol), p-methoxybenzoyl chloride (10.2 g, 60.0 mmol), and aluminu-
m(iii) chloride (8.4 g, 63.0 mmol) a yield of 64% (8.75 g) was obtained after
chromatography (hexanes/MTBE 4:1). Red solid; m.p. 1308C; IR (KBr):
nÄmax ˆ 3114 (w), 2954 (w), 2840 (w), 1633 (s), 1615 (s), 1598 (vs), 1441 (s),
1292 (s), 1164 (s), 1029 (m), 844 (m), 770 (m); 1H NMR (CDCl3, 200 MHz):
d ˆ 7.83 ± 7.77 (m, 4H), 6.89 ± 6.83 (m, 4H), 4.66 (t, J ˆ 1.9 Hz, 4H), 4.52 (t,
J ˆ 1.9 Hz, 4H), 3.84 (s, 6H); 13C NMR (CDCl3, 50 MHz): d ˆ 196.10,
162.62, 131.63, 130.43, 113.41, 80.01, 74.13, 73.03, 55.34; MS (EI, 70 eV): m/z
‡
‡
(EI, 70 eV): m/z (%): 396 (M , 94), 394 (M , 100), 358 (16), 183 (38), 92
(41); C18H20Cl2FeO2 (395.11): calcd C 54.72, H 5.10; found C 54.55, H 5.18.
1,1'-Bis(g-carbomethoxypropanoyl)ferrocene (5e): From ferrocene (0.80 g,
4.30 mmol), 3-carbomethoxypropanoyl chloride (2.26 g, 15.0 mmol), and
aluminum(iii) chloride (6.0 g, 45.0 mmol) a yield of 40% (0.71 g) was
obtained after chromatography (hexanes/MTBE 1:1). Red solid; m.p. 100 ±
-1018C; IR (film): nÄmax ˆ 3100 (w), 3000 (w), 2960 (m), 2930 (w), 2860 (w),
1740 (vs), 1670 (vs), 1455 (m), 1370 (m), 1230 (s), 1085 (m), 845 (m); 1H
NMR (CDCl3, 300 MHz): d ˆ 4.74 (t, J ˆ 1.8 Hz, 4H), 4.45 (t, J ˆ 1.8 Hz,
4H), 3.58 (s, 6H), 2.89 (t, J ˆ 6.4 Hz, 4H), 2.56 (t, J ˆ 6.3 Hz, 4H); 13C
NMR (CDCl3, 75 MHz): d ˆ 200.98, 173.04, 79.46, 73.39, 70.35, 51.40, 34.05,
‡
(%): 454 (M , 100), 319 (4), 255 (7), 135 (12); C26H22FeO4 (454.31): calcd C
68.74, H 4.85; found C 68.74, H 4.88.
1,1'-Bis(p-fluorobenzoyl)ferrocene (5l): From ferrocene (1.86 g,
10.0 mmol), p-fluorobenzoyl chloride (3.57 g, 22.5 mmol), and aluminu-
m(iii) chloride (3.32 g, 25.0 mmol, 14 h reaction time) a yield of 67%
(2.90 g) was obtained after chromatography (hexanes/MTBE 3:1). Red
solid; m.p. 1278C; IR (KBr): nÄmax ˆ 3105 (w), 3092 (w), 1639 (vs), 1630 (s),
1506 (s), 1290 (s), 855 (m), 770 (s); 1H NMR (CDCl3, 200 MHz): d ˆ 7.82 ±
7.75 (m, 4H), 7.12 ± 7.04 (m, 4H), 4.86 (t, J ˆ 1.9 Hz, 4H), 4.57 (t, J ˆ 1.9 Hz,
4H); 13C NMR (CDCl3, 50 MHz): d ˆ 196.14, 164.99 (d, J ˆ 253 Hz),
135.13, 130.57 (d, J ˆ 9.1 Hz), 115.38 (d, J ˆ 21.6 Hz), 79.52, 74.37, 73.19;
‡
27.09; MS (EI, 70 eV): m/z (%): 414 (M , 100), 383 (5), 235 (22), 175 (24),
115 (20); C20H22FeO6 (414.24): calcd C 57.99, H 5.35; found C 57.71, H 5.50.
1,1'-Bis(b-methylpropanoyl)ferrocene (5 f): From ferrocene (1.10 g,
6.00 mmol), 2-methylpropanoyl chloride (1.70 g, 16.0 mmol), and alumi-
num(iii) chloride (2.4 g, 18.0 mmol) a yield of 75% (1.47 g) was obtained
after chromatography (hexanes/MTBE 5:1). Red solid; m.p. 1248C; IR
(film): nÄmax ˆ 3100 (w), 2965 (s), 2935 (m), 2875 (w), 1660 (vs), 1450 (s), 1380
(m), 1245 (s), 1050 (m), 835 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.70 ±
4.66 (m, 4H), 4.43 ± 4.38 (m, 4H), 3.00 ± 2.92 (m, 2H), 1.14 ± 1.08 (m, 12H);
13C NMR (CDCl3, 75 MHz): d ˆ 207.54, 79.07, 73.30, 70.48, 37.24, 19.14; MS
‡
MS (EI, 70 eV): m/z (%): 430 (M , 100), 243 (12), 151 (19); C24H16F2FeO2
(430.23): calcd C 67.00, H 3.75; found C 66.85, H 4.04.
1,1'-Di(a-naphthoyl)ferrocene (5m): From ferrocene (1.86 g, 10.0 mmol),
1-naphthoyl chloride (4.36 g, 22.5 mmol), and aluminum(iii) chloride
(3.32 g, 25.0 mmol) a yield of 72% (3.56 g) was obtained after chromatog-
raphy (hexanes/MTBE 4:1). Red solid; m.p. 1328C; IR (KBr): nÄmax ˆ 3086
(w), 3046 (w), 1642 (vs), 1445 (m), 1285 (s), 786 (s); 1H NMR (CDCl3,
200 MHz): d ˆ 8.01 ± 7.96 (m, 2H), 7.68 ± 7.64 (m, 4H), 7.46 ± 7.08 (m, 8H),
4.69 (m, 4H), 4.42 ± 4.41 (m, 4H); 13C NMR (CDCl3, 50 MHz): d ˆ 199.32,
136.31, 133.36, 130.92, 129.84, 128.19, 126.86, 126.04, 125.93, 123.83, 80.71,
‡
(EI, 70 eV): m/z (%): 326 (M , 100), 283 (62), 213 (15), 185 (16), 121 (20);
C18H22FeO2 (326.22): calcd C 66.27, H 6.80; found C 65.96, H 6.88.
1,1'-Bis(cyclohexylcarbonyl)ferrocene (5g): From ferrocene (1.10 g,
6.00 mmol), cyclohexylcarbonyl chloride (2.40 g, 18.0 mmol), and alumi-
num(iii) chloride (2.4 g, 18.0 mmol) a yield of 80% (1.96 g) was obtained
after chromatography (hexanes/MTBE 5:1). Red solid; m.p. 134 ± 1358C;
IR (KBr): nÄmax ˆ 3134 (w), 2930 (s), 2853 (m), 1663 (vs), 1449 (s), 1382 (w),
1265 (m), 1225 (m), 840 (w); 1H NMR (CDCl3, 200 MHz): d ˆ 4.74 (t, J ˆ
1.8 Hz, 4H), 4.45 (t, J ˆ 1.8 Hz, 4H), 2.76 ± 2.65 (m, 2H), 1.85 ± 1.25 (m,
20H); 13C NMR (CDCl3, 50 MHz): d ˆ 207.00, 79.38, 73.35, 70.51, 47.77,
‡
74.07, 72.46; MS (EI, 70 eV): m/z (%): 494 (M , 100), 339 (18), 273 (29), 183
(32), 127 (23); C32H22FeO2 (494.37): calcd C 77.74, H 4.49; found C 77.65, H
4.64.
1,1'-Di(b-naphthoyl)ferrocene (5n): From ferrocene (1.86 g, 10.0 mmol), 2-
naphthoyl chloride (4.20 g, 22.0 mmol), and aluminum(iii) chloride (3.50 g,
26.0 mmol) a yield of 35% (1.72 g) was obtained after chromatography
(hexanes/MTBE/CH2Cl2 4:1:1). Red solid; m.p. 183 ± 1848C; IR (KBr):
nÄmax ˆ 3100 (w), 3055 (w), 1642 (vs), 1447 (m), 1294 (s), 810 (m), 778 (s), 757
(m); 1H NMR (CDCl3, 300 MHz): d ˆ 8.30 ± 8.29 (m, 2H), 7.84 ± 7.73 (m,
8H), 7.58 ± 7.51 (m, 4H), 4.99 (t, J ˆ 1.9 Hz, 4H), 4.63 (t, J ˆ 1.9 Hz, 4H);
13C NMR (CDCl3, 75 MHz): d ˆ 197.54, 136.23, 134.91, 132.25, 129.16,
128.97, 128.11, 127.84, 127.73, 126.65, 124.48, 79.86, 74.49, 73.29; MS (EI,
‡
29.53, 25.81; MS (EI, 70 eV): m/z (%): 406 (M , 100), 323 (5), 213 (4), 185
(7), 121 (12), 81 (5); C24H30FeO2 (406.35): calcd C 70.94, H 7.44; found C
70.86, H 7.37.
1,1'-Dipivaloylferrocene (5h): From ferrocene (1.11 g, 6.00 mmol), pivaloyl
chloride (2.10 g, 18.0 mmol), and aluminum(iii) chloride (1.76 g, 18.0 mmol)
a yield of 26% (0.55 g) was obtained after chromatography (hexanes/
MTBE 10:1). (A suspension of aluminum(iii) chloride in CH2Cl2 was added
dropwise to a solution of ferrocene and pivaloyl chloride). Red solid; m.p.
125 ± 1268C; IR (KBr): nÄmax ˆ 3112 (w), 2954 (m), 2927 (m), 2869 (w), 1654
(vs), 1476 (m), 1438 (m), 1368 (m), 1287 (m), 1213 (m), 1070 (m), 874 (m);
1H NMR (CDCl3, 200 MHz): d ˆ 4.84 (t, J ˆ 1.8 Hz, 4H), 4.41 (t, J ˆ 1.8 Hz,
4H), 1.29 (s, 18H); 13C NMR (CDCl3, 50 MHz): d ˆ 209.54, 77.78, 73.46,
‡
70 eV): m/z (%): 494 (M , 100), 183 (22), 155 (48), 127 (21), 84 (46), 73 (85),
49 (86); C32H22FeO2 (494.37): calcd C 77.74, H 4.49; found C 77.48, H 4.48.
1,1'-Diacetylruthenocene (7a): From ruthenocene (0.75 g, 3.25 mmol),
acetyl chloride (785 mg, 10.0 mmol), and aluminum(iii) chloride (1.60 g,
12.0 mmol) a yield of 34% (0.35 g) was obtained after chromatography
(hexanes/ethyl acetate 1:2). Yellow solid; m.p. 136 ± 1428C; IR (KBr):
nÄmax ˆ 3100 (w), 2920 (m), 2851 (w), 1666 (vs), 1459 (m), 1447 (m), 1378 (m),
1279 (s), 1114 (s), 1040 (w), 828 (m); 1H NMR (CDCl3, 200 MHz): d ˆ 5.07
(t, J ˆ 1.5 Hz, 4H), 4.77 (t, J ˆ 1.6 Hz, 4H), 2.16 (s, 6H); 13C NMR (CDCl3,
50 MHz): d ˆ 198.56, 85.68, 74.97, 72.56, 26.68; MS (EI, 70 eV): m/z (%):
‡
72.08, 44.36, 27.94; MS (EI, 70 eV): m/z (%): 354 (M , 100), 297 (45), 205
(27); C20H26FeO2 (354.27): calcd C 67.81, H 7.40; found C 67.90, H 7.36.
1,1'-Dibenzoylferrocene (5i): From ferrocene (1.11 g, 6.00 mmol), benzoyl
chloride (2.50 g, 17.8 mmol), and aluminum(iii) chloride (2.4 g, 18 mmol) a
yield of 82% (1.95 g) was obtained after chromatography (hexanes/MTBE
3:1). Red solid; m.p. 97 ± 1008C; IR (KBr): nÄmax ˆ 3267 (w), 3113 (w), 3064
(w), 1637 (vs), 1448 (s), 1288 (s), 1048 (m), 846 (m), 726 (s), 698 (s); 1H
NMR (CDCl3, 200 MHz): d ˆ 7.77 ± 7.72 (m, 4H), 7.50 ± 7.38 (m, 6H), 4.88
(t, J ˆ 1.8 Hz, 4H), 4.53 (t, J ˆ 1.8 Hz, 4H); 13C NMR (CDCl3, 50 MHz):
d ˆ 197.71, 138.94, 131.76, 128.18, 127.95, 79.36, 74.46, 72.95; MS (EI,
‡
316 (M , 100), 301 (52), 245 (40), 167 (26), 43 (37); C14H14O2Ru (315.33):
calcd C 53.36, H 4.47; found C 53.43, H 4.63.
1,1'-Dihexanoylruthenocene (7b): From ruthenocene (0.46 g, 2.00 mmol),
hexanoyl chloride (538 mg, 4.00 mmol), and aluminum(iii) chloride (1.06 g,
8.0 mmol) a yield of 34% (0.35 g) was obtained after chromatography
(hexanes/ethyl acetate 5:1). Yellow solid; m.p. 708C; IR (KBr): nÄmax ˆ 3103
(w), 2953 (m), 2930 (s), 2860 (m), 1677 (vs), 1465 (m), 1260 (m), 1218 (m),
‡
70 eV): m/z (%): 394 (M , 100), 289 (2), 225 (3), 77 (7); C24H18FeO2
(394.25): calcd C 73.12, H 4.60; found C 72.86, H 4.83.
1
820 (s); H NMR (CDCl3, 200 MHz): d ˆ 5.06 (t, J ˆ 1.8 Hz, 4H), 4.73 (t,
1,1'-Di(o-toluoyl)ferrocene (5j): From ferrocene (1.43 g, 7.70 mmol), o-
toluoyl chloride (2.50 g, 16.2 mmol), and aluminum(iii) chloride (2.25 g,
16.9 mmol) a yield of 73% (2.36 g) was obtained after chromatography
J ˆ 1.8 Hz, 4H), 2.45 (t, J ˆ 7.4 Hz, 4H), 1.70 ± 1.45 (m, 4H), 1.35 ± 1.15 (m,
8H), 0.87 (t, J ˆ 6.6 Hz, 6H); 13C NMR (CDCl3, 50 MHz): d ˆ 201.45,
85.30, 74.75, 72.18, 39.01, 31.49, 24.14, 22.44, 13.89; MS (EI, 70 eV): m/z
958
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0958 $ 17.50+.50/0
Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
‡
‡
(%): 428 (M , 100), 372 (29), 357 (45), 329 (29), 231 (47), 97 (53), 69 (62), 55
(EI, 70 eV): m/z (%): 526 (M , 93), 412 (78), 249 (91), 57 (100); C28H38FeO6
(51), 43 (74); C22H30O2Ru (427.55): calcd C 61.80, H 5.19; found C 61.62, H
5.26.
(526.45): calcd C 63.88, H 7.28; found C 63.61, H 7.47.
General procedure C for the metallocenyl diols 4 and 10: Preparation of
the oxazaborolidine 9: (S)-a,a-Diphenylprolinol (1.50 g, 6.00 mmol),
methaneboronic acid (360 mg, 6.00 mmol), and toluene (25 mL) were
heated to reflux for 5 h. Water was removed with the help of a Dean ± Stark
trap. The solvent was evaporated under vacuum to leave a solid, which was
directly used in the next step.
1,1'-Dibenzoylruthenocene(7c): From ruthenocene (924 mg, 4.00 mmol),
benzoyl chloride (1.30 g, 9.00 mmol), and aluminum(iii) chloride (1.60 g,
12.0 mmol, 2 h at reflux) a yield of 50% (899 mg) was obtained after
chromatography (hexanes/ethyl acetate 3:1). Yellow solid; m.p. 124 ±
1258C; IR (KBr): nÄmax ˆ 3092 (w), 3063 (w), 1637 (vs), 1449 (m), 1372 (s),
1286 (s), 725 (s); 1H NMR (CDCl3, 200 MHz): d ˆ 7.83 ± 7.78 (m, 4H),
7.49 ± 7.35 (m, 6H), 5.20 (t, J ˆ 1.9 Hz, 4H), 4.86 (t, J ˆ 1.8 Hz, 4H); 13C
NMR (CDCl3, 50 MHz): d ˆ 195.90, 138.71, 128.35, 128.20, 84.08, 75.87,
CBS reduction of metallocenyl diketones 5 and 7: The oxazaborolidine 9
(330 mg, 1.20 mmol) was dissolved in THF (12 mL) and cooled to 08C
under argon. From a syringe charged with BH3 ´ SMe2 (1m in THF, 4 mL)
20% of the final amount (0.8 mL) was added to the catalyst solution. After
5 min stirring the remaining BH3 ´ SMe2 and a solution of the diketone
(2.00 mmol) in THF (5 mL) were added simultaneously within 20 min. The
red color of the ketone turned to yellow on reduction. After 15 min at 08C
the excess BH3 ´ SMe2 was quenched by dropwise addition of methanol
(2 mL; caution: gas evolution!). After the hydrolysis had ceased the
mixture was poured into saturated aqueous NH4Cl (150 mL) and extracted
with ether (200 mL). The organic layer was washed with water (2 Â
100 mL) and brine (100 mL), dried, and then concentrated to give an oil,
which was purified by column chromatography.
‡
74.90; MS (EI, 70 eV): m/z (%): 440 (M , 100), 363 (6), 335 (2), 306 (20),
105 (24), 77 (26); C24H18O2Ru (439.48): calcd C 65.59, H 4.13; found C
65.21, H 4.19.
1-Acetyl-1'-pentamethylferrocene (8a): From pentamethylferrocene
(415 mg, 1.42 mmol), acetyl chloride (170 mg, 2.30 mmol), and aluminu-
m(iii) chloride (276 mg, 2.00 mmol) a yield of 29% (124 mg) was obtained
after chromatography (hexanes/MTBE 3:1). A mixture of the acid chloride
and aluminum(iii) chloride was added to a solution of the metallocene
within 1 h. Red solid; m.p. 99 ± 1008C; IR (KBr): nÄmax ˆ 3093 (w), 3078 (w),
2953 (m), 2912 (s), 2855 (m), 1656 (vs), 1453 (s), 1378 (m), 1276 (s), 1111
(w), 1031 (m), 819 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.22 (t, J ˆ 1.9 Hz,
2H), 4.01 (t, J ˆ 1.9 Hz, 2H), 2.22 (s, 3H), 1.79 (s, 15H); 13C NMR (CDCl3,
75 MHz): d ˆ 201.02, 81.31, 80.85, 76.50, 72.00, 27.58, 10.45; MS (EI, 70 eV):
For comparison (NMR, HPLC) racemic samples of the diols 4 and 10 were
prepared by LiAlH4 or NaBH4 reduction of the diketones 5 and 7. They
contained comparable amounts of the dl and meso diastereomers.
‡
m/z (%): 298 (M , 100), 255 (23), 133 (10), 121 (11); C17H22FeO (298.21):
(R,R)-1,1'-Bis(a-hydroxyethyl)ferrocene (4a): Diketone 5a (540 mg,
2.00 mmol) was reduced with 60 mol% 9 and the crude product purified
by chromatography (hexanes/MTBE 1:1). Yield: 535 mg (98%; dl:meso ˆ
98.5:1.5, ee >99%). Yellow solid; m.p. 70 ± 728C; HPLC (OD, 5% iPrOH,
0.9 mL/min, 215 nm): tR/min ˆ 11.11 (SS and RS), 15.72 (RR). [a]d ˆ 97.7
(c ˆ 2.34, CHCl3), 78.1 (c ˆ 2.84, benzene (dl:meso 84:16)); IR (KBr):
nÄmax ˆ 3301 (s), 3103 (w), 3080 (w), 2970 (m), 1366 (m), 1094 (s), 1004 (s),
calcd C 68.47, H 7.44; found C 68.66, H 7.68.
1-Hexanoyl-1'-pentamethylferrocene (8b): From pentamethylferrocene
(350 mg, 1.10 mmol), hexanoyl chloride (206 mg, 1.53 mmol), and alumi-
num(iii) chloride (256 mg, 1.92 mmol) a yield of 30% (119 mg) was
obtained after chromatography (hexanes/MTBE 10:1). A mixture of the
acid chloride and aluminum(iii) chloride was added to a solution of the
metallocene within 1 h. Red oil; IR (film): nÄmax ˆ 3080 (w), 2920 (vs), 2870
(s), 1655 (vs), 1445 (s), 1375 (s), 1250 (m), 1065 (m), 1025 (m), 820 (m); 1H
NMR (CDCl3, 300 MHz): d ˆ 4.23 (t, J ˆ 1.9 Hz, 2H), 3.99 (t, J ˆ 1.9 Hz,
2H), 2.53 (t, J ˆ 7.8 Hz, 2H), 1.79 (s, 15H), 1.73 ± 1.54 (m, 2H), 1.36 ± 1.30
(m, 4H), 0.91 ± 0.87 (m, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 203.55,
81.33, 80.63, 76.17, 71.67, 40.08, 31.70, 24.20, 22.50, 13.90, 10.54; MS (EI,
1
804 (m); H NMR (CDCl3, 300 MHz): d ˆ 5.15 (s)/5.12 (s, 2H total), 4.64
(q, J ˆ 6.2 Hz, dl)/4.60 (q, J ˆ 6.2 Hz, meso, 2H total), 4.25 ± 4.24 (m, meso)/
4.16 ± 4.15 (m)/4.14 ± 4.13 (m)/4.12 ± 4.11 (m, 8H total), 1.39 (d, J ˆ 6.6 Hz,
meso)/1.36 (d, J ˆ 6.6 Hz, dl, 6H total); 13C NMR (CDCl3, 75 MHz): d ˆ
95.20, 67.57, 67.48, 66.13, 65.92, 65.40, 25.56 (dl); 67.74, 67.32, 66.52, 65.50,
‡
65.06, 25.16 (meso, separated signals); MS (EI, 70 eV): m/z (%): 274 (M ,
‡
70 eV): m/z (%): 354 (M , 100), 255 (14), 133 (9), 121 (8); C21H30FeO
12), 256 (100), 241 (8), 213 (13), 164 (53), 147 (16), 121 (15), 92 (23);
C14H18FeO2 (274.14): calcd C 61.34, H 6.62; found C 61.44, H 6.52.
(354.32): calcd C 71.19, H 8.53; found C 70.91, H 8.54.
General procedure B for diacyl ferrocenes 5 by zinc ± copper reagent
substitution of 1,1'-ferrocenedicarbonyl dichloride (6): Under argon
copper(i) cyanide (262 mg, 2.92 mmol) and lithium chloride (248 mg,
5.85 mmol) were dissolved in THF (2.5 mL). At 788C the dialkylzinc
reagent (3.00 mmol) was added dropwise. After the addition was finished
the solution was warmed to 08C for 5 min and then cooled again to 788C.
1,1'-Ferrocenedicarbonyl dichloride (6, 303 mg, 0.98 mmol) in THF (3 mL)
was added within 15 min. The reaction was warmed to 258C, stirred for
5 h, and then poured into saturated aqueous NH4Cl (20 mL). After
extraction with ether (4 Â 50 mL) the combined organic layers were dried
and concentrated to give an oil, which was purified by column chromatog-
raphy.
(R,R)-1,1'-Bis(a-hydroxypropyl)ferrocene (4b): Diketone 5o (75 mg,
0.25 mmol) was reduced with 60 mol% 9 and the crude product purified
by chromatography (hexanes/MTBE 2:1). Yield: 73 mg (97%; dl:meso ˆ
90:10, ee ˆ 99.8%). Yellow oil; HPLC (OD, 5% iPrOH, 0.9 mL/min,
215 nm): tR/min ˆ 6.52 (SS), 7.28 (RS), 9.58 (RR); [a]d ˆ 92.4 (c ˆ 1.31,
benzene). IR (film): nÄmax ˆ 3320 (s), 3080 (w), 2930 (m), 2860 (m), 1460 (m),
1380 (m), 1030 (s), 810 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 5.04 (s)/4.94 (s,
2H total), 4.43 (t, J ˆ 6.2 Hz, dl)/4.32 (t, J ˆ 6.2 Hz, meso, 2H total), 4.27 ±
4.26 (m, meso)/4.22 ± 4.21 (m, dl, 2H total), 4.15 ± 4.10 (m, 6H), 1.74 ± 1.48
(m, 4H), 0.93 (t, J ˆ 7.4 Hz, meso)/0.87 (t, J ˆ 7.4 Hz, dl, 6H total); 13C
NMR (CDCl3, 75 MHz): d ˆ 93.45, 71.29, 67.34, 67.31, 66.32, 66.30, 32.69,
9.79 (dl); 93.90, 70.49, 67.44, 67.24, 66.93, 65.41, 31.88, 10.02 (meso); MS (EI,
‡
70 eV): m/z (%): 302 (M , 22), 284 (44), 266 (100), 255 (12), 226 (15), 178
(24), 160 (68), 91 (75); C16H22 FeO2 (302.20): calcd C 63.59, H 7.34; found C
63.43, H 7.41.
1,1'-Dipropionylferrocene (5o): From 1,1'-ferrocenedicarbonyl dichloride
(6, 303 mg, 0.98 mmol) and diethylzinc (370 mg, 3.00 mmol) a yield of 87%
(259 mg) was obtained after chromatography (hexanes/MTBE 3:1). Red
solid; m.p. 50 ± 518C; IR (KBr): nÄmax ˆ 3096 (w), 2934 (w), 1674 (vs), 1458
(s), 1242 (s), 1102 (m), 1048 (m), 807 (m); 1H NMR (CDCl3, 300 MHz): d ˆ
4.88 ± 4.85 (m, 4H), 4.59 ± 4.56 (m, 4H), 2.84 ± 2.71 (m, 4H), 1.34 ± 1.23 (m,
6H); 13C NMR (CDCl3, 75 MHz): d ˆ 203.68, 79.90, 72.92, 70.17, 32.68,
(R,R)-1-(a-Hydroxyethyl)-1'-(a-hydroxyhexyl)ferrocene (4c): Diketone
5b (163 mg, 0.50 mmol) was reduced with 60 mol% of 9 and the crude
product purified by chromatography (hexanes/MTBE 2:1). Yield: 155 mg
(94%; (RR):(RS) ˆ 90:10). Yellow oil; [a]d ˆ 47.1 (c ˆ 2.07, CHCl3); IR
(film): nÄmax ˆ 3330 (vs), 3095 (w), 2935 (s), 2860 (s), 1400 (m), 1370 (m),
1100 (m), 1040 (m), 810 (m), 760 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 4.94
(s, 2H), 4.67 (q, J ˆ 6.3 Hz, RR)/4.60 (q, J ˆ 6.3 Hz, SR, 1H total), 4.46 (t,
J ˆ 6.5 Hz, RR)/4.41 (t, J ˆ 6.4 Hz, SR, 1H total), 4.26 ± 4.12 (m, 8H), 1.64 ±
1.17 (m, 8H), 1.42 (d, J ˆ 6.4 Hz, SR)/1.37 (d, J ˆ 6.4 Hz, RR, 3H total),
0.87 ± 0.83 (m, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 95.07, 94.14, 69.78,
67.50, 67.41, 67.37, 67.30, 66.39, 66.12, 65.76, 65.69, 39.79, 31.75, 25.89, 25.27,
13.94 (RR); 95.22, 94.19, 69.48, 67.68, 67.22, 66.77, 66.05, 65.59, 65.34, 64.74,
39.50, 31.73, 24.77 (SR, separated signals); MS (EI, 70 eV): m/z (%): 330
‡
7.82; MS (EI, 70 eV): m/z (%): 298 (M , 100), 269 (24), 213 (27), 186 (6), 121
(27); C16H18FeO2 (298.16): calcd C 64.45, H 6.08; found C 64.25, H 6.05.
1,1'-Bis(d-pivaloxybutanoyl)ferrocene (5p): From 1,1'-ferrocene dicarbo-
nyldichloride (6, 435 mg, 1.40 mmol) and di(3-pivaloxypropyl)zinc (from 3-
iodopropyl pivalate (1.62 g, 6.0 mmol) and diethylzinc (1 mL)) a yield of
80% (590 mg) was obtained after chromatography (hexanes/MTBE 2:1).
Red oil; IR (KBr): nÄmax ˆ 3100 (w), 2960 (s), 1720 (vs), 1670 (vs), 1455 (m),
1380 (w), 1280 (s); 1H NMR (CDCl3, 200 MHz): d ˆ 4.66 (t, J ˆ 1.8 Hz,
4H), 4.38 (t, J ˆ 1.9 Hz, 4H), 4.07 (t, J ˆ 6.4 Hz, 4H), 2.62 (t, J ˆ 7.2 Hz,
4H), 1.92 (quin, J ˆ 6.8 Hz, 4H), 1.10 (s, 18H); 13C NMR (CDCl3, 50 MHz):
d ˆ 202.02, 177.24, 79.99, 73.25, 70.38, 63.47, 38.59, 35.82, 27.08, 22.96; MS
‡
(M , 91), 312 (35), 294 (5), 241 (10), 200 (91), 164 (51), 92 (100); C18H26FeO2
(330.25): calcd C 65.47, H 7.94; found C 65.49, H 7.63.
Chem. Eur. J. 1998, 4, No. 5
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0959 $ 17.50+.25/0
959

P. Knochel, L. Schwink
FULL PAPER
(R,R)-1,1'-Bis(a-hydroxyhexyl)ferrocene (4d): Diketone 5c (191 mg,
0.50 mmol) was reduced with 200 mol% 9 and the crude product purified
by chromatography (hexanes/MTBE 4:1). Yield: 190 mg (98%; dl:meso ˆ
91:9, ee >99%). Yellow oil; HPLC (OD, 2% iPrOH, 1.0 mLmin 1, 254 nm):
tR/min ˆ 6.10 (SS), 7.40 (RS), 8.69 (RR); [a]d ˆ 29.6 (c ˆ 2.30, CHCl3); IR
(film): nÄmax ˆ 3320 (s), 3090 (w), 2920 (vs), 2860 (s), 1460 (m), 1400 (w), 1380
(w), 1115 (m), 1040 (s), 810 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.85 ±
4.65 (s, 2H), 4.47 (t, J ˆ 6.3 Hz, dl)/4.38 (dd, J ˆ 7.3, 5.1 Hz, meso, 2H total),
4.27 ± 4.26 (m, meso)/4.21 ± 4.20 (m, dl, 2H total), 4.15 ± 4.10 (m, 6H), 1.65 ±
1.20 (m, 16H), 0.86 (t, J ˆ 6.6 Hz, meso)/0.84 (t, J ˆ 6.9 Hz, dl, 6H total);
13C NMR (CDCl3, 75 MHz): d ˆ 93.75, 69.87, 67.27, 67.18, 66.13, 65.97, 39.86,
31.04, 25.04, 22.38, 13.79 (dl); 94.12, 69.07, 67.12, 67.09, 66.71, 65.16, 39.04,
purified by chromatography (hexanes/MTBE 4:1). Yield: 205 mg (99%;
dl:meso ˆ 80:20, ee ˆ 97.6%). Yellow solid; m.p. 100 ± 1048C; HPLC (OD,
1% iPrOH, 1.0 mLmin 1, 254 nm): tR/min ˆ 7.80 (SS), 8.82 (RS), 14.51
(RR); [a]d ˆ 18.2 (c ˆ 2.30, CHCl3); IR (KBr): nÄmax ˆ 3350 (s), 3090 (w),
2920 (s), 2855 (s), 1445 (m), 1400 (m), 1215 (s), 1040 (s), 1015 (s), 810 (m),
755 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 4.45 (s, 2H), 4.30 ± 4.06 (m, 10H),
1.77 ± 0.78 (m, 22H); 13C NMR (CDCl3, 75 MHz): d ˆ 91.61, 74.66, 67.18,
67.12, 67.02, 66.97, 45.52, 28.83, 28.30, 26.35, 26.09, 26.04 (dl); 92.89, 73.82,
67.69, 67.33, 65.63, 45.22, 28.76 (meso, separated signals); MS (EI, 70 eV):
‡
m/z (%): 410 (M , 48), 392 (100), 374 (40), 326 (1), 309 (8), 280 (8), 227 (11),
212 (40), 121 (18), 83 (43); C24H34FeO2 (410.38): calcd C 70.24, H 8.35;
found C 70.11, H 8.60.
‡
31.62, 25.25 (meso, separated signals); MS (EI, 70 eV): m/z (%): 386 (M ,
42), 368 (77), 350 (55), 200 (100), 121 (21), 92 (68), 78 (31); C22H34FeO2
(386.36): calcd C 68.39, H 8.87; found C 68.40, H 8.93.
(R,R)-1,1'-Bis(a-hydroxy-b,b-dimethylpropyl)ferrocene (4j): Diketone 5g
(177 mg, 0.50 mmol) was reduced with 60 mol% 9 (18 h at room temper-
ature) and purified by chromatography (hexanes/MTBE 4:1). Yield:
178 mg (99%; dl:meso ˆ 51:49). Yellow solid; m.p. 110 ± 1148C; IR
(KBr): nÄmax ˆ 3499 (s), 3094 (w), 2961 (s), 2865 (m), 1461 (m), 1363 (s),
1062 (s), 998 (m), 820 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.26 (s, meso)/
4.19 (s, dl, 2H total), 4.15 ± 4.00 (m, 8H), 3.20 (s)/2.65 (s, 2H total), 0.82 (s,
18H); 13C NMR (CDCl3, 75 MHz): d ˆ 90.43, 78.56, 68.60, 67.58, 67.22,
67.02, 35.54, 25.75 (dl); 91.77, 77.87, 69.41, 67.51, 67.29, 65.99, 35.30, 25.89
(R,R)-1,1'-Bis(a-hydroxy-d-chlorobutyl)ferrocene (4e): Diketone 5d
(934 mg, 2.36 mmol) was reduced with 60 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 1:1). Yield: 861 mg (91%;
dl:meso ˆ 94:6). Yellow oil; [a]d ˆ 14.9 (c ˆ 1.62, CHCl3); IR (KBr):
nÄmax ˆ 3414 (s), 3100 (w), 2953 (m), 1026 (s), 810 (m); 1H NMR (CDCl3,
300 MHz): d ˆ 4.65 (s, 2H), 4.53 (t, J ˆ 5.6 Hz, 2H), 4.19 ± 4.15 (m, 8H),
3.50 (t, J ˆ 6.0 Hz, 4H), 1.86 ± 1.69 (m, 8H); 13C NMR (CDCl3, 75 MHz):
d ˆ 93.20, 69.38, 67.77, 66.43, 66.18, 45.01, 36.91, 28.56 (dl); 93.54, 68.83,
68.72, 66.92, 65.49, 36.22, 28.78 (meso, separated signals); MS (EI, 70 eV):
‡
(meso); MS (EI, 70 eV): m/z (%): 358 (M , 100), 283 (87), 214 (37), 119
(39); C20H30FeO2 (358.30): calcd C 67.04, H 8.44; found C 67.02, H 8.78.
(R,R)-1,1'-Bis(a-hydroxyphenylmethyl)ferrocene (4k): Diketone 5i
(197 mg, 0.50 mmol) was reduced with 60 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 3:1). Yield: 177 mg (89%;
dl:meso ˆ 94:6). Repeated crystallization from MTBE gave dl:meso ˆ 98:2.
Yellow solid; m.p. 130 ± 1328C; HPLC (OD, 5% iPrOH, 1.0 mL/min,
‡
‡
m/z (%): 382 ([M
H2O], 72), 380 ([M
H2O], 100), 362 (31), 172 (19),
117 (30); C18H24Cl2FeO2 (399.14): calcd C 54.17, H 6.06; found C 54.30, H 6.17.
(R,R)-1,1'-Bis(a-hydroxy-d-pivaloxybutyl)ferrocene (4 f): Diketone 5p
(220 mg, 0.41 mmol) was reduced with 60 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 3:1). Yield: 178 mg (82%;
dl:meso ˆ 89:11, ee > 99%). Yellow oil; HPLC (OD, 10% iPrOH,
0.9 mLmin 1, 215 nm): tR/min ˆ 7.70 (SS), 8.80 (RR), 9.86 (RS); [a]d ˆ
28.5 (c ˆ 0.53, benzene); IR (film): nÄmax ˆ 3360 (s), 3090 (w), 2960 (vs),
2880 (s), 1725 (vs), 1480 (m), 1400 (m), 1370 (w), 1290 (s), 1160 (vs), 1040
(m), 810 (w); 1H NMR (CDCl3, 300 MHz): d ˆ 4.67 (s, 2H), 4.47 ± 4.46 (m,
dl)/4.38 ± 4.36 (m, meso, 2H total), 4.19 ± 4.18 (m, meso)/4.14 ± 4.13 (m)/
4.10 ± 4.09 (m)/4.06 ± 4.04 (m, 8H total), 3.97 ± 3.94 (m, 4H), 1.75 ± 1.52 (m,
8H), 1.11 (s, meso)/1.10 (s, dl, 18H total); 13C NMR (CDCl3, 75 MHz): d ˆ
178.55, 93.54, 69.52, 67.70, 66.45, 66.14, 64.19, 38.69, 36.01, 27.04, 24.77 (dl);
93.90, 68.86, 67.83, 67.60, 66.90, 65.43, 35.35, 24.95 (meso, separated signals);
254 nm): tR/min ˆ 23.23 (SS and RS), 25.55 (RR). [a]D
ˆ
75.1 (c ˆ 0.05,
CHCl3), 74.3 (c ˆ 0.97, benzene); IR (KBr): nÄmax ˆ 3526 (vs), 3081 (w),
3026 (w), 1491 (m), 1452 (m), 1049 (m), 1017 (m), 828 (m), 721 (s), 699 (s);
1H NMR (CDCl3, 300 MHz): d ˆ 7.35 ± 7.20 (m, 10H), 5.42 (s, 4H), 4.43 (s)/
4.27 (s, meso)/4.22 (s)/4.16 (s)/4.11 (s)/4.04 (s, meso, 8H total); 13C NMR
(CDCl3, 75 MHz): d ˆ 144.19, 128.13, 127.19, 126.13, 93.45, 72.49, 67.98,
67.79, 66.67, 66.60 (dl); 143.73, 128.03, 93.94, 71.60, 68.13, 67.54, 67.10, 66.36
‡
(meso, separated signals); MS (EI, 70 eV): m/z (%): 398 (M , 35), 380 (50),
226 (14), 154 (100); C24H22FeO2 (398.28): calcd C 72.38, H 5.57; found C
72.32, H 5.68.
(R,R)-1,1'-Bis(a-hydroxy-o-tolylmethyl)ferrocene (4l): Diketone 5j
(580 mg, 1.37 mmol) was reduced with 60 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 5:2). Yield: 551 mg (94%;
‡
MS (EI, 70 eV): m/z (%): 530 (M , 58), 512 (48), 494 (8), 428 (41), 190 (31),
57 (100); C28H42FeO6 (530.48): calcd C 63.40, H 7.98; found C 63.62, H 7.93.
(R,R)-1,1'-Bis(a-hydroxy-g-carbomethoxypropyl)ferrocene (4g): Dike-
tone 5e (207 mg, 0.50 mmol) was reduced with 60 mol% 9 and the crude
product purified by chromatography (hexanes/MTBE 1:1). Yield: 176 mg
(84%; dl:meso ˆ 96:4). Yellow oil; [a]d ˆ 23.7 (c ˆ 1.77, CHCl3); IR
(film): nÄmax ˆ 3380 (s), 3100 (w), 2950 (s), 1730 (vs), 1440 (m), 1260 (s), 1165
dl:meso ˆ 95:5). Yellow solid; m.p. 1388C; [a]D
ˆ
46.3 (c ˆ 0.67, CHCl3);
IR (KBr): nÄmax ˆ 3270 (vs), 3077 (w), 2926 (w), 1043 (s), 820 (m), 738 (s); 1H
NMR (CDCl3, 300 MHz): d ˆ 7.49 ± 7.46 (m, meso)/7.35 ± 7.31 (m, dl, 2H
total), 7.14 ± 7.00 (m, 6H), 5.70 (s, dl)/5.60 (s, meso, 2H total), 5.27 (s, meso)/
5.24 (s, 2H total), 4.32 ± 4.31 (m, dl)/4.23 ± 4.22 (m)/4.17 ± 4.16 (m, meso)/
4.10 ± 4.09 (m, dl)/4.02 ± 4.01 (m, meso, 8H total); 13C NMR (CDCl3,
75 MHz): d ˆ 142.04, 134.82, 130.08, 127.10, 126.23, 125.81, 93.42, 68.76,
67.91, 67.63, 67.55, 66.69, 19.06 (dl); 141.81, 134.69, 129.97, 127.04, 126.07,
93.54, 68.07, 67.99, 67.30, 18.95 (meso, separated signals); MS (EI, 70 eV): m/
1
(s), 1070 (s), 1020 (m), 810 (w); H NMR (CDCl3, 300 MHz): d ˆ 4.61 (s,
2H), 4.51 (t, J ˆ 5.9 Hz, dl)/4.42 (dd, J ˆ 7.0, 5.0 Hz, 2H total), 4.28 (s,
meso)/4.15 ± 4.14 (m)/4.12 ± 4.10 (m)/4.09 ± 4.07 (m, 8H total), 2.43 ± 2.30
(m, 4H), 1.96 ± 1.81 (m, 4H); 13C NMR (CDCl3, 75 MHz): d ˆ 174.35, 92.83,
69.00, 67.71, 67.61, 66.35, 66.18, 51.48, 34.19, 29.91 (dl); 93.19, 68.34, 67.78,
67.52, 66.69, 65.50, 33.67, 30.10 (meso, separated signals); MS (EI, 70 eV):
‡
z (%): 426 (M , 51), 407 (6), 168 (100), 153 (29); C26H26FeO2 (426.34): calcd
C 73.25, H 6.15; found C 73.21, H 5.99.
‡
m/z (%): 418 (M , 100), 400 (17), 386 (33), 369 (19), 354 (62), 235 (34), 164
(R,R)-1,1'-Bis(a-hydroxy-p-methoxyphenylmethyl)ferrocene (4m): Dike-
tone 5k (454 mg, 1.00 mmol) was reduced with 60 mol% 9 and the crude
product purified by chromatography (hexanes/MTBE 3:1). Yield: 265 mg
(58%; dl:meso ˆ 92:8). Yellow solid; m.p. 1088C; [a]D ˆ ‡22.4 (c ˆ 0.41,
CHCl3); IR (KBr): nÄmax ˆ 3270 (vs), 3086 (w), 3000 (w), 2869 (w), 1610 (m),
1511 (s), 1251 (s), 1039 (s), 831 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 7.25 ±
7.19 (m, 4H), 6.82 ± 6.75 (m, 4H), 5.48 ± 5.42 (m, 2H), 4.91 (s, 2H), 4.44 ±
4.43 (m, dl)/4.30 ± 4.29 (m, meso)/4.25 ± 4.24 (m, dl)/4.18 ± 4.17 (m, meso)/
4.15 ± 4.13 (m), 4.09 ± 4.08 (m, meso, 8H total); 13C NMR (CDCl3, 75 MHz):
d ˆ 158.86, 136.72, 127.42, 113.62, 93.69, 72.22, 68.06, 67.78, 66.70, 66.55,
(52), 105 (62); C20H26FeO6 (418.27): calcd C 57.43, H 6.27; found C 57.53, H 6.30.
(R,R)-1,1'-Bis(a-hydroxy-b-methylpropyl)ferrocene (4h): Diketone 5 f
(169 mg, 0.50 mmol) was reduced with 200 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 3:1). Yield: 150 mg (91%;
dl:meso ˆ 94:6, ee > 99%). Yellow solid; m.p. 60 ± 628C; HPLC (OD, 1%
iPrOH, 1.0 mLmin 1, 254 nm): tR/min ˆ 7.49 (SS), 11.46 (RS), 12.55 (RR).
[a]d ˆ 46.7 (c ˆ 1.62, CHCl3), 85.0 (c ˆ 1.08, benzene); IR (KBr): nÄmax
ˆ
3240 (vs), 3090 (w), 2955 (vs), 2875 (s), 1460 (m), 1385 (m), 1365 (m), 1255
(m), 1040 (s), 810 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 4.28 ± 4.07 (m,
12H), 1.78 ± 1.65 (m, 2H), 0.88 ± 0.76 (m, 12H); 13C NMR (CDCl3,
75 MHz): d ˆ 91.52, 75.40, 67.26, 67.24, 67.13, 67.08, 35.67, 18.06, 18.03
(dl); 92.55, 74.60, 67.78, 67.29, 67.26, 65.63, 35.34, 18.36, 18.17 (meso); MS
55.18 (dl); 113.53, 71.40, 68.20, 67.06, 66.32 (meso, separated signals); MS
‡
(EI, 70 eV): m/z (%): 440 ([M
H2O], 100), 317 (24), 256 (47), 182 (15),
105 (19), 70 (25); C26H26FeO4 (458.32): calcd C 68.14, H 5.72; found C 68.02,
H 6.11.
‡
(EI, 70 eV): m/z (%): 330 (M , 100), 212 (7), 294 (5), 269 (24), 240 (14), 192
(28), 174 (57), 121 (15), 105 (62); C18H26FeO2 (330.25): calcd C 65.47, H 7.94;
found C 65.73, H 8.20.
(R,R)-1,1'-Bis(a-hydroxy-p-fluorophenylmethyl)ferrocene (4n): Diketone
5l (500 mg, 1.16 mmol) was reduced with 60 mol% 9 and the crude product
purified by chromatography (hexanes/MTBE 3:1). Yield: 475 mg (94%;
dl:meso ˆ 90:10). Yellow solid; m.p. 1348C; [a]d ˆ 4.3 (c ˆ 1.11, CHCl3);
(R,R)-1,1'-Bis(a-hydroxycyclohexylmethyl)ferrocene (4i): Diketone 5g
(203 mg, 0.50 mmol) was reduced with 60 mol% 9 and the crude product
960
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0960 $ 17.50+.50/0
Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
IR (KBr): nÄmax ˆ 3285 (vs), 3081 (w), 2867 (w), 1602 (m), 1508 (s), 1219 (s),
1045 (m), 842 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 7.27 ± 7.14 (m, 4H),
6.96 ± 6.84 (m, 4H), 5.49 ± 5.30 (m, 4H), 4.42 ± 4.41 (m, dl)/4.26 ± 4.25 (m)/
4.22 ± 4.19 (m, meso)/4.16 ± 4.15 (m)/4.08 ± 4.07 (m, meso, 8H total); 13C
NMR (CDCl3, 75 MHz): d ˆ 162.02 (d, J ˆ 246 Hz), 140.00 (d, J ˆ 3.0 Hz),
127.73 (d, J ˆ 8.1 Hz), 114.98 (d, J ˆ 21.4 Hz), 93.30, 72.00, 68.27, 67.98,
66.58, 66.53 (dl); 139.48 (d, J ˆ 3.0 Hz), 114.91 (d, J ˆ 21.4 Hz), 93.84, 71.14,
68.40, 67.70, 67.09, 66.24 (meso, separated signals); MS (EI, 70 eV): m/z
dl:meso ˆ 95:5). Pale yellow solid; m.p. 139 ± 1408C; [a]d ˆ 158.5 (c ˆ
0.74, CHCl3); IR (KBr): nÄmax ˆ 3365 (vs), 3078 (w), 3022 (w), 2870 (w), 1489
1
(m), 1450 (m), 1409 (m), 1386 (m), 1038 (m), 819 (s), 716 (s), 699 (m); H
NMR (CDCl3, 300 MHz): d ˆ 7.37 ± 7.25 (m, 10H), 5.30 (s, dl)/5.27 (s, meso,
2H, total), 4.75 ± 4.72 (m) / 4.62 ± 4.61 (m)/4.57 ± 4.53 (m)/4.50 ± 4.48 (m,
meso, 8H total), 3.86 (s, meso)/3.76 (s, dl, 2H total); 13C NMR (CDCl3,
75 MHz): d ˆ 143.65, 128.47, 127.71, 126.43, 99.17, 71.32, 70.85, 70.77, 70.70,
70.08 (dl); 143.59, 128.44, 99.21, 71.11, 70.92 (meso, separated signals); MS
‡
‡
(%): 434 (M , 13), 416 (78), 401 (4), 244 (23), 172 (100), 152 (21); C24H20
(EI, 70 eV): m/z (%): 444 (M , 17), 426 (13), 409 (2), 321 (29), 105 (100);
F2FeO2 (434.27): calcd C 66.38, H 4.64; found C 66.50, H 4.53.
C24H22O2Ru (443.51): calcd C 65.00, H 5.00; found C 64.84, H 4.99.
(R,R)-1,1'-Bis(a-hydroxy-(1-naphthyl)methyl)ferrocene (4o): Diketone
5m (499 mg, 1.01 mmol) was reduced with 60 mol% of 9 and the crude
product purified by chromatography (hexanes/MTBE 3:1). Yield: 374 mg
(74%; dl:meso ˆ 94:6). Yellow solid; m.p. 1428C; [a]D ˆ ‡78.9 (c ˆ 0.55,
CHCl3); IR (KBr): nÄmax ˆ 3344 (vs), 3047 (w), 2923 (w), 1510 (m), 1393 (w),
1043 (m), 783 (vs); 1H NMR (CDCl3, 300 MHz): d ˆ 8.17 ± 8.12 (m, 2H),
7.85 ± 7.76 (m, 2H), 7.65 (d, J ˆ 8.0 Hz, 2H), 7.44 ± 7.37 (m, 6H), 7.31 (t, J ˆ
7.5 Hz, 2H), 6.20 (s, dl)/6.14 (s, meso, 2H total), 5.23 (s, 2H), 4.36 ± 4.35 (m,
dl)/4.27 ± 4.26 (m, dl)/4.22 ± 4.21 (m, dl)/4.15 ± 4.14 (m, meso)/4.09 ± 4.07 (m,
dl), 3.98 ± 3.97 (m, meso, 8H total); 13C NMR (CDCl3, 75 MHz): d ˆ 139.59,
133.65, 130.74, 128.56, 128.07, 125.88, 125.38, 125.24, 124.08, 123.73, 93.15,
69.17, 68.20, 67.76, 67.18 (dl); 139.31, 133.54, 127.93, 125.82, 125.35, 123.87,
93.42, 68.33, 67.90, 67.70, 67.53 (meso, separated signals); MS (EI, 70 eV): m/
(R)-1-(a-Hydroxyethyl)-1'-pentamethylferrocene (11a): Ketone 8a
(70 mg, 0.23 mmol) was reduced according to general procedure C with
30 mol% of 9 and the crude product was purified by chromatography
(hexanes/MTBE 5:1). Yield: 60 mg (87%; ee >95%). The enantiomeric
excess was determined by addition of 4 mol% Eu(hfc)3 to a 1H NMR
sample (CDCl3, 500 MHz) and integration of separated diastereomeric
signals at d ˆ 4.42 (s) and 4.38 (s). Yellow solid; m.p. 78 ± 798C; [a]d ˆ
52.2 (c ˆ 1.09, CHCl3); IR (KBr): nÄmax ˆ 3437 (vs), 3086 (w), 2969 (s), 2946
(s), 1455 (m), 1067 (s), 866 (m), 812 (m); 1H NMR (CDCl3, 300 MHz): d ˆ
4.58 ± 4.53 (m, 1H), 3.78 (s, 1H), 3.67 (s, 2H), 3.64 (s, 1H), 1.89 (s, 15H),
1.76 ± 1.75 (m, 1H), 1.38 (d, J ˆ 6.3 Hz, 3H); 13C NMR (CDCl3, 75 MHz):
d ˆ 93.74, 80.14, 72.35, 72.12, 68.23, 67.67, 65.39, 34.07, 11.23; MS (EI,
‡
70 eV): m/z (%): 300 (M , 100), 282 (14), 208 (49), 190 (98), 133 (21);
‡
z (%): 498 (M , 4), 480 (46), 337 (20), 203 (100); C32H26FeO2 (498.40): calcd
C17H24FeO (300.22): calcd C 68.01, H 8.06; found C 68.34, H 8.21.
C 77.12, H 5.26; found C 76.83, H 5.26.
(R)-1-(a-Hydroxyhexyl)-1'-pentamethylferrocene (11b): Ketone 8b
(90 mg, 0.25 mmol) was reduced according to general procedure C with
30 mol% 9 and the crude product purified by chromatography (hexanes/
MTBE 10:1). Yield: 83 mg (91%; ee ˆ 95%). The enantiomeric excess was
determined by addition of 3 mol% Eu(hfc)3 to a 1H NMR sample and
integration of separated diastereomeric signals at d ˆ 4.27 (s) and 4.14 (s).
Yellow oil; [a]d ˆ 38.9 (c ˆ 3.74, CHCl3); IR (film): nÄmax ˆ 3440 (m), 3070
(w), 2920 (s), 2860 (s), 1460 (m), 1380 (m), 1035 (m), 815 (m); 1H NMR
(CDCl3, 300 MHz): d ˆ 4.31 (t, J ˆ 5.6 Hz, 1H), 3.80 ± 3.63 (m, 4H), 1.88 (s,
15H), 1.65 ± 1.25 (m, 9H), 0.89 (t, J ˆ 6.7 Hz, 3H); 13C NMR (CDCl3,
75 MHz): d ˆ 93.66, 80.18, 72.18, 72.06, 69.30, 66.87, 38.71, 31.83, 25.63,
(R,R)-1,1'-Bis(a-hydroxy-(2-naphthyl)methyl)ferrocene (4p): Diketone
5n (996 mg, 2.00 mmol) was reduced with 60 mol% 9 and the crude
product purified by chromatography (hexanes/THF 1:1) and crystallization
from THF. Yield: 793 mg (80%; dl:meso ˆ 97:3). Yellow solid; m.p. 187 ±
1888C; [a]D ˆ ‡61.5 (c ˆ 0.63, THF); IR (KBr): nÄmax ˆ 3380 (s), 3053 (w),
2863 (w), 1054 (m), 1017 (m), 786 (m), 751 (m); 1H NMR ([D8]THF,
300 MHz): d ˆ 7.76 ± 7.64 (m, 8H), 7.49 ± 7.43 (m, 2H), 7.32 ± 7.28 (m, 4H),
5.65 ± 5.64 (m, 2H), 5.61 (d, J ˆ 2.5 Hz, dl)/5.56 (d, J ˆ 3.1 Hz, meso, 2H
total), 4.39 (m, dl)/4.26 ± 4.25 (m, meso, 2H total), 4.16 ± 4.11 (m)/4.03 ± 3.96
(m, 6H total), 2.50 (s, 2H); 13C NMR ([D8]THF, 75 MHz): d ˆ 142.90,
133.03, 132.92, 127.30, 126.82, 125.09, 124.76, 124.35, 123.85, 94.06, 71.92,
67.26, 67.10, 66.40, 66.22 (dl); 142.61, 124.45, 123.97, 94.38, 71.21, 67.35,
‡
22.59, 13.99, 11.20; MS (EI, 70 eV): m/z (%): 356 (M , 83), 338 (93), 208
(67), 190 (100), 174 (19), 133 (29); C21H32FeO (356.33): calcd C 70.79, H
9.05; found C 70.83, H 9.10.
‡
66.91, 66.22 (meso, separated signals); MS (EI, 70 eV): m/z (%): 498 (M ,
11), 494 (16), 480 (100), 276 (23), 204 (45); C32H26FeO2 (498.40): calcd C
77.12, H 5.26; found C 76.90, H 5.44.
General procedure D for the acetates 12, 13, and 14: The metallocenyl diol
(2.92 mmol) was treated under argon with acetic anhydride (2 mL) and
pyridine (5 mL) and the solution was stirred for 12 h at room temperature.
Volatile matter was removed in vacuum (0.7 mmHg, 5 h). The crude
product was already >95% pure, as indicated by NMR analysis. The yield
was quantitative. If desired the acetates can be further purified by rapid
column chromatography on silica gel deactivated by addition of NEt3 to the
eluent. Care should be taken as the acetates 12, 13, and 14 are strong
alkylating agents and therefore potentially carcinogenic.
(R,R)-1,1'-Bis(a-hydroxyethyl)ruthenocene (10a): Diketone 7a (126 mg,
0.40 mmol) was reduced with 60 mol% of 9 and the crude product purified
by chromatography (hexanes/MTBE 1:1). Yield: 95 mg (74%; dl:meso ˆ
87:13). Pale yellow solid; m.p. 86 ± 888C; [a]d ˆ 45.5 (c ˆ 2.36, CHCl3); IR
(KBr): nÄmax ˆ 3265 (vs), 3099 (w), 2970 (m), 1393 (w), 1364 (m), 1096 (s),
1021 (m), 807 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 4.66 ± 4.65 (m, 2H),
4.60 ± 4.58 (m, 2H), 4.50 ± 4.49 (m, 4H), 4.42 ± 4.34 (m, 2H), 3.45 (s, 2H),
1.34 (d, J ˆ 6.3 Hz, meso)/1.33 (d, J ˆ 6.3 Hz, dl, 6H total); 13C NMR
(CDCl3, 75 MHz): d ˆ 99.91, 70.06, 70.00, 69.48, 68.73, 63.97, 24.45 (dl);
99.78, 70.15, 69.95, 69.55, 68.52, 64.35, 24.69 (meso); MS (EI, 70 eV): m/z
(R,R)-1,1'-Bis(a-acetoxyethyl)ferrocene (12a): The diol 4a (805 mg,
2.92 mmol) was treated with acetic anhydride (2 mL) and pyridine
(5 mL) to give a quantitative yield of the diacetate 12a (dl:meso ˆ 98:2).
Yellow solid; m.p. 57 ± 588C; [a]d ˆ 58.5 (c ˆ 1.41, CHCl3); IR (KBr):
nÄmax ˆ 3104 (w), 3082 (w), 2997 (m), 2947 (w), 1729 (vs), 1369 (m), 1238 (vs),
1040 (s), 838 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 5.72 (q, J ˆ 6.6 Hz, 2H),
4.17 ± 4.14 (m, 2H), 4.10 ± 4.08 (m, 2H), 4.06 ± 4.04 (m, 4H), 1.95 (s, 6H),
1.46 (d, J ˆ 6.6 Hz)/1.45 (d, J ˆ 6.6 Hz, 6H total); 13C NMR (CDCl3,
75 MHz): d ˆ 169.86, 169.84, 88.50, 88.43, 68.80, 68.56, 68.46, 68.14, 68.11,
66.34, 66.32, 20.97, 20.04, 19.84 (signal set of the diastereomeric mixture);
‡
(%): 320 (M , 83), 302 (33), 287 (31), 259 (100), 232 (30), 167 (29), 43 (93);
C14H18O2Ru (319.37): calcd C 52.65, H 5.68; found C 52.65, H 5.80.
(R,R)-1,1'-Bis(a-hydroxyhexyl)ruthenocene (10b): Diketone 7b (171 mg,
0.40 mmol) was reduced with 60 mol% 9 and the crude product purified by
chromatography (hexanes/MTBE 3:1). Yield: 150 mg (87%; dl:meso ˆ
86:14, ee ˆ 99%). Pale yellow solid; m.p. 40 ± 428C; HPLC (OD, 2.5%
iPrOH, 0.5 mLmin 1, 254 nm): tR/min ˆ 11.04 (SS), 11.46 (RS), 11.84 (RR).
‡
[a]D
ˆ
53.0 (c ˆ 2.37, CHCl3); IR (film): nÄmax ˆ 3320 (s), 3095 (w), 2930
MS (EI, 70 eV): m/z (%): 358 (M , 12), 206 (8), 147 (7), 92 (100);
(vs), 2865 (s), 1710 (w), 1655 (w), 1465 (m), 1045 (s), 810 (m); 1H NMR
(CDCl3, 500 MHz): d ˆ 4.73 ± 4.72 (m, meso)/4.71 ± 4.70 (m, meso/4.69 ±
4.68 (m, dl)/4.66 ± 4.65 (m, dl, 4H total), 4.57 ± 4.55 (m, 4H), 4.16 ± 4.11
(m, 2H), 2.49 (s, 2H), 1.70 ± 1.25 (m, 16H), 0.90 (t, J ˆ 6.6 Hz, 6H). 13C
NMR (CDCl3, 200 MHz): d ˆ 99.44, 70.38, 70.13, 69.89, 68.56, 68.32, 38.48,
31.72, 25.68, 22.56, 13.98 (dl); 70.41, 70.17, 69.91, 68.44, 68.21 (meso,
C18H22FeO4 (358.22): calcd C 60.35, H 6.19; found C 60.62, H 6.30.
(R,R)-1,1'-Bis(a-acetoxyhexyl)ferrocene (12b): The diol 4d (270 mg,
0.69 mmol) was treated with acetic anhydride (1.5 mL) and pyridine
(4 mL) to give a quantitative yield of the diacetate 12b. Yellow oil; [a]d ˆ
20.6 (c ˆ 1.90, CHCl3); IR (film): nÄmax ˆ 3095 (w), 2956 (s), 2933 (vs), 2861
(s), 1737 (vs), 1468 (m), 1372 (s), 1243 (vs), 1014 (s), 829 (m); 1H NMR
(CDCl3, 300 MHz): d ˆ 5.70 (t, J ˆ 6.5 Hz, 2H), 4.18 ± 4.16 (m, 2H), 4.09 ±
4.08 (m, 2H), 4.07 ± 4.05 (m, 4H), 2.07 (s, 6H), 1.80 ± 1.70 (m, 4H), 1.23 (s,
12H), 0.86 (t, J ˆ 6.7 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 170.30,
88.72, 88.69, 71.75, 68.72, 68.42, 67.92, 67.85, 67.09, 67.02, 35.22, 35.17, 31.41,
25.22, 22.40, 21.07, 13.84 (signal set of the diastereomeric mixture);
‡
separated signals); MS (EI, 70 eV): m/z (%): 432 (M , 32), 414 (24), 343
(33), 99 (100), 71 (48); C22H34O2Ru (431.58): calcd C 61.23, H 7.94; found C
61.22, H 8.20.
(R,R)-1,1'-Bis(a-hydroxyphenylmethyl)ruthenocene (10c): Diketone 7c
(1.47 g, 3.43 mmol) was reduced with 60 mol% of 9 and the crude product
purified by chromatography (hexanes/MTBE 3:1). Yield: 1.36 g (92%;
‡
MS (EI, 70 eV): m/z (%): 470 (M , 15), 410 (3), 350 (17), 262 (42), 200
Chem. Eur. J. 1998, 4, No. 5
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0961 $ 17.50+.25/0
961

P. Knochel, L. Schwink
FULL PAPER
(8), 92 (100), 148 (18); C26H38FeO4 (470.43): calcd C 66.38, H 8.14; found C
66.33, H 7.98.
(R,R)-1,1'-Bis(a-acetoxy-phenylmethyl)ruthenocene (13): The diol 10c
(1.45 g, 3.26 mmol) was treated with acetic anhydride (5 mL) and pyridine
(12 mL) to give a quantitative yield of the diacetate 13 (dl:meso >96:4).
Pale yellow solid; m.p. 113 ± 1148C; [a]d ˆ ‡77.6 (c ˆ 0.88, CHCl3); IR
(KBr): nÄmax ˆ 3067 (w), 3030 (w), 2931 (w), 1737 (vs), 1368 (m), 1229 (vs),
1017 (m), 816 (m), 729 (m), 699 (m); 1H NMR (CDCl3, 300 MHz): d ˆ
7.36 ± 7.28 (m, 10H), 6.47 (s, dl)/6.45 (s, meso, 2H total), 4.70 ± 4.69 (m, dl)/
4.62 ± 4.61 (m, meso)/4.43 ± 4.42 (m)/4.38 ± 4.37 (m)/4.30 ± 4.29 (m, 8H
total), 2.09 (s, dl)/2.08 (s, meso, 6H total); 13C NMR (CDCl3, 75 MHz):
d ˆ 169.61, 139.82, 127.97, 127.81, 126.93, 92.16, 73.44, 71.74, 71.63, 70.99
(dl); 139.73, 127.85, 126.99, 73.49, 71.83, 71.69, 71.53, 71.10 (meso, separated
(R,R)-1,1'-Bis(a-acetoxy-d-chlorobutyl)ferrocene (12c): The diol 4d
(399 mg, 1.00 mmol) was treated with acetic anhydride (2 mL) and pyridine
(4 mL) to give a quantitative yield of the diacetate 12c. Yellow oil; [a]d ˆ
19.0 (c ˆ 1.02, CHCl3); IR (film): nÄmax ˆ 3093 (w), 2962 (w), 1737 (vs),
1372 (s), 1242 (s), 1025 (s) 832 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 5.74
(dd, J ˆ 8.7, 3.9 Hz, 2 H), 4.20 ± 4.19 (m, 2H), 4.12 ± 4.08 (m, 6H), 3.59 ± 3.49
(m, 4H), 2.12 ± 1.99 (m, 2H), 2.06 (s, 6H), 1.91 ± 1.74 (m, 6H); 13C NMR
(CDCl3, 75 MHz): d ˆ 170.34, 88.12, 70.86, 68.97, 68.72, 68.11, 67.07, 44.43,
32.27, 28.51, 21.07 (dl); 67.00 (meso, separated signal); MS (EI, 70 eV): m/z
‡
signals); MS (EI, 70 eV): m/z (%): 528 (M , 56), 469 (20), 425 (22), 374 (83),
315 (100), 255 (51), 105 (41), 43 (23); C28H26O4Ru (527.58): calcd C 63.75, H
4.97; found C 63.59, H 4.80.
‡
‡
(%): 484 (M , 10), 482 (M , 15), 380 (33), 268 (31), 154 (100),
119 (35); C22H28Cl2FeO4 (483.22): calcd C 54.68, H 5.84; found C 54.60,
H 5.77.
(R)-1-(a-Acetoxyethyl)-1'-pentamethylferrocene (14): The alcohol 11a
(90 mg, 0.30 mmol) was treated with acetic anhydride (2 mL) and pyridine
(2 mL) to give a quantitative yield of the acetate 14. Yellow oil; [a]d ˆ
93.7 (c ˆ 1.46, CHCl3); IR (KBr): nÄmax ˆ 3087 (w), 2906 (s), 1733 (vs), 1372
(s), 1245 (s), 1023 (s), 814 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 5.78 (q,
J ˆ 6.4 Hz, 1H), 3.76 ± 3.75 (m, 1H), 3.67 ± 3.65 (m, 3H), 1.87 (s, 15H), 2.03
(s, 3H), 1.49 (d, J ˆ 6.5 Hz, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 170.53,
87.66, 80.37, 72.89, 71.99, 70.35, 68.71, 67.60, 21.48, 19.95, 11.12; MS (EI,
(R,R)-1,1'-Bis(a-acetoxy-g-carbomethoxypropyl)ferrocene (12d): The di-
ol 4g (536 mg, 1.28 mmol) was treated with acetic anhydride (2 mL) and
pyridine (4 mL) to give after chromatography (hexanes/MTBE 1:1, 1%
NEt3) the diacetate 12d. Yield: 545 mg (85%). Yellow oil; [a]d ˆ 35.3
(c ˆ 1.12, CHCl3); IR (film): nÄmax ˆ 3090 (w), 2950 (m), 1730 (vs), 1440 (m),
1370 (s), 1240 (vs), 1020 (s), 835 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 5.71
(dd, J ˆ 9.0, 3.5 Hz, 2H), 4.19 ± 4.18 (m, 2H), 4.11 ± 4.10 (m, 2H), 4.09 ± 4.08
(m, 4H), 3.62 (s, 6H), 2.31 (t, J ˆ 6.6 Hz, 4H), 2.26 ± 2.11 (m, 2H), 2.07 ±
1.95 (m, 2H), 2.02 (s, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 173.08, 170.22,
87.63, 70.76, 69.03, 68.76, 68.24, 66.92, 51.48, 29.99, 20.95; MS (EI, 70 eV):
‡
70 eV): m/z (%): 342 (M , 24), 300 (4), 282 (100), 250 (94), 190 (32),
133 (18); C19H26FeO2 (342.26): calcd C 66.68, H 7.66; found C 67.04,
H 7.53.
‡
m/z (%): 502 (M , 33), 442 (19), 382 (76), 278 (60), 219 (43), 189 (43), 189
(18), 164 (100), 135 (22), 105 (63); C24H30FeO8 (502.35): calcd C 57.38, H
6.02; found C 57.41, H 6.06.
General procedure E for the reaction of metallocenyl acetates with amines
in THF/H2O or MeOH/H2O: The metallocenyl acetate (1.23 mmol) was
dissolved in MeOH (10 mL; THF (10 mL) was used for the more reactive
aryl-substituted acetates and the derivatives of pentamethylferrocene). An
excess of the amine (2 g) together with water (2 mL) was added. More
MeOH (THF) was added if the mixture was not a clear solution at this
point. After stirring for 12 h at room temperature the reaction mixture was
poured into saturated aqueous NH4Cl (50 mL) and extracted with ether
(100 mL). After washing with water (2 Â 50 mL) and brine (50 mL) the
organic layer was dried and concentrated to give an oil, which was purified
by column chromatography.
(R,R)-1,1'-Bis(a-acetoxy-b-methylpropyl)ferrocene (12e): The diol 4h was
dissolved in pyridine (2 mL) and acetic anhydride (1 mL), acetyl chloride
(0.3 mL), and DMAP (30 mg) were added at 08C. After stirring for 2 h at
room temperature the reaction was poured into saturated aqueous
NaHCO3 (20 mL) and extracted into ether (40 mL). After washing with
water (20 mL) and brine (20 mL) the organic layer was dried and
evaporated to give an oil, which was purified by rapid column chromatog-
raphy (hexanes/MTBE 3:1, 1% NEt3). Yield: 202 mg (88%, dl:meso ˆ
90:10). Yellow oil; [a]d ˆ ‡3.5 (c ˆ 1.24, CHCl3); IR (film): nÄmax ˆ 3080
(w), 2930 (s), 1720 (vs), 1440 (m), 1370 (s), 1240 (vs), 1020 (m), 820 (m); 1H
NMR (CDCl3, 300 MHz): d ˆ 5.60 (d, J ˆ 5.3 Hz, dl)/5.58 (d, J ˆ 5.7 Hz,
meso, 2H total), 4.06 ± 4.00 (m, 8H), 2.19 (s, meso)/2.16 (s, dl, 6H total),
1.84 ± 1.73 (m, 2H), 0.77 (d, J ˆ 6.7 Hz, 6H), 0.76 (d, J ˆ 6.7 Hz, 6H); 13C
NMR (CDCl3, 75 MHz): d ˆ 170.07, 87.67, 76.26, 68.73, 68.42, 68.21, 66.31,
34.19, 21.09, 18.24, 17.77 (dl); 170.25, 68.28, 68.07, 67.88, 66.74, 34.25, 18.13,
(R)-1-(a-N,N-Dimethylaminoethyl)-1'-pentamethylferrocene (15): The
acetate 14 (200 mg, 0.58 mmol) was treated with dimethylamine (40% in
water, 1.5 mL) in THF/water. Chromatography (THF with 1% NEt3) gave
the amine 15 (180 mg, 95%). The enantiomeric excess could be estimated
by comparison with a literature value of optical rotation[18] to be >96%.
Yellow oil; [a]d ˆ 10.1 (c ˆ 0.76, CHCl3); IR (film): nÄmax ˆ 3080 (w), 2900
‡
1
17.68 (meso, separated signals); MS (EI, 70 eV): m/z (%): 414 (M , 20), 354
(vs), 2780 (w), 1450 (m), 1375 (m), 1030 (m), 810 (m); H NMR (CDCl3,
(4), 294 (14), 234 (74), 120 (47), 105 (100); C22H30FeO4 (414.32): calcd C
63.78, H 7.30; found C 63.48, H 7.20.
300 MHz): d ˆ 3.65 ± 3.57 (m, 5H), 2.05 (s, 6H), 1.86 (s, 15H), 1.32 (d, J ˆ
6.8 Hz, 3H); 13C NMR (CDCl3, 125 MHz): d ˆ 87.24, 79.74, 72.42, 71.63,
‡
71.21, 68.62, 57.22, 40.30, 13.76, 11.13; MS (EI, 70 eV): m/z (%): 327 (M ,
(R,R)-1,1'-Bis(a-acetoxyphenylmethyl)ferrocene (12 f): The diol 4k
(143 mg, 0.36 mmol) was treated with acetic anhydride (1 mL) and pyridine
(3 mL) to give a quantitative yield of the diacetate 12 f (dl:meso ˆ 93:7).
Yellow oil; [a]d ˆ 30.0 (c ˆ 1.81, CHCl3); IR (film): nÄmax ˆ 3089 (w), 3066
(w), 3035 (m), 2937 (w), 1733 (vs), 1372 (s), 1241 (vs), 1019 (s), 830 (m), 731
69), 312 (51), 282 (100), 156 (21). The analytical data are in accord with
those in the literature.[18]
(R)-1-(a-Methoxyethyl)-1'-pentamethylferrocene (16): The above reaction
leading to 15 carried out in MeOH/water instead of THF/water gave the
undesired methoxy derivative 16 in quantitative yield. Yellow oil; [a]d ˆ
17.25 (c ˆ 1.31, CHCl3); IR (film): nÄmax ˆ 3087 (w), 2970 (m), 2903 (s),
2817 (w), 1453 (m), 1380 (s), 1113 (s), 814 (m); 1H NMR (CDCl3,
300 MHz): d ˆ 4.15 (q, J ˆ 5.9 Hz, 1H), 3.78 (s, 1H), 3.72 (s, 3H), 3.27 (s,
3H), 1.80 (s, 15H), 1.45 (d, J ˆ 6.2 Hz, 3H); 13C NMR (CDCl3, 50 MHz):
d ˆ 88.85, 79.95, 73.97, 72.42, 71.75, 70.49, 67.55, 54.93, 19.15, 11.12; MS (EI,
1
(s), 700 (s); H NMR (CDCl3, 200 MHz): d ˆ 7.30 ± 7.26 (m, 10H), 6.59 (s,
2H), 4.26 ± 4.25 (m, dl)/4.18 ± 4.17 (m, meso)/4.04 ± 4.02 (m)/3.99 ± 3.98 (m)/
3.94 ± 3.93 (m, meso)/3.86 ± 3.85 (m, dl, 8H total), 2.04 (s, dl)/2.03 (s, meso,
6H total); 13C NMR (CDCl3, 50 MHz): d ˆ 169.75, 139.82, 128.15, 127.93,
127.04, 88.32, 73.89, 69.21, 69.10, 68.43, 68.22, 21.12; MS (EI, 70 eV): m/z
‡
(%): 482 (M , 16), 364 (18), 269 (8), 208 (7), 154 (100); C28H26FeO4
‡
(482.36): calcd C 69.72, H 5.43; found C 69.67, H 5.72.
70 eV): m/z (%): 314 (M , 85), 282 (33), 222 (20), 190 (100); C18H26FeO
(314.25): calcd C 68.80, H 8.34; found C 68.87, H 8.33.
(R,R)-1,1'-Bis(a-acetoxy-(2-naphthyl)methyl)ferrocene (12g): The diol 4o
(867 mg, 1.74 mmol) was treated with acetic anhydride (3 mL) and pyridine
(7 mL) to give a quantitative yield of the diacetate 12g (dl:meso ˆ 86:14).
Yellow oil; [a]d ˆ 3.5 (c ˆ 0.51, CHCl3); IR (KBr): nÄmax ˆ 3054 (w), 2957
(w), 1732 (vs), 1373 (m), 1233 (vs), 1043 (m), 1021 (m), 788 (m), 761 (m); 1H
NMR (CDCl3, 300 MHz): d ˆ 7.89 ± 7.87 (m, 8H), 7.55 ± 7.49 (m, 6H), 6.96
(s, meso)/6.90 (s, dl, 2H total), 4.48 ± 4.47 (m, dl)/4.40 ± 4.39 (m, meso, 2H
(R,R)-1,1'-Bis(a-N,N-dimethylaminoethyl)ferrocene (17a): The diacetate
12a (390 mg, 1.09 mmol) was treated with dimethylamine (40% in water,
2 mL) in MeOH/water. Chromatography (MTBE with 5% NEt3) gave the
diamine 17a (325 mg, 91%, dl:meso ˆ 98:2). Yellow oil; [a]d ˆ ‡28.7 (c ˆ
0.63, CHCl3); IR (film): nÄmax ˆ 3080 (w), 2940 (s), 2780 (m), 1450 (m), 1370
(m), 1040 (m), 825 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 3.96 ± 3.94 (m,
8H), 3.48 (q, J ˆ 6.9 Hz, 2H), 1.97 (s, 12H), 1.34 (d, J ˆ 6.9 Hz)/1.33 (d, J ˆ
6.8 Hz, 6H total); 13C NMR (CDCl3, 75 MHz): d ˆ 87.28, 70.13, 68.28,
68.02, 66.90, 58.46, 40.55, 15.94 (dl); 87.41, 69.83, 68.08, 67.80, 67.17, 58.37,
total), 4.21 ± 4.13 (m)/4.02 ± 4.01 (m, dl, 6H), 2.18 (s)/2.16 (s, 6H total); 13
C
NMR (CDCl3, 75 MHz): d ˆ 169.70, 137.21, 132.88, 127.94, 127.52, 126.08,
124.85, 88.44, 74.07, 69.23, 69.16, 68.50, 68.41, 68.35, 21.08 (dl); 137.30,
132.91, 124.90, 88.54, 74.02, 21.05 (meso, separated signals); MS (EI, 70 eV):
‡
40.50, 15.78 (meso); MS (EI, 70 eV): m/z (%): 328 (M , 39), 283 (79), 239
(100), 225 (36), 178 (32), 149 (39), 72 (56); C18H28FeN2 (328.28): calcd C
65.86, H 8.60, N 8.53; found C 65.63, H 8.90, N 8.46.
‡
m/z (%): 582 (M , 1), 464 (18), 203 (81), 60 (62), 45 (100); C36H30FeO4
(582.48): calcd C 74.23, H 5.22; found C 74.34, H 5.19.
962
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0962 $ 17.50+.50/0
Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
(R,R)-1,1'-Bis(a-N,N-dimethylaminohexyl)ferrocene (17b): The diacetate
12b (140 mg, 0.30 mmol) was treated with dimethylamine (40% in water,
2 mL) in MeOH/water. The crude product showed dl:meso ˆ 89:11 by
NMR analysis. Chromatography (hexanes/MTBE 3:1 with 5% NEt3) gave
the diastereomerically pure diamine 17b (118 mg, 90%). Yellow oil; [a]d ˆ
‡24.2 (c ˆ 3.15, CHCl3); IR (film): nÄmax ˆ 3091 (w), 2956 (s), 2930 (vs), 2856
(s), 2821 (m), 2779 (m), 1457 (m), 1027 (m), 826 (m); 1H NMR (CDCl3,
300 MHz): d ˆ 3.99 ± 3.98 (m, 2H), 3.97 ± 3.96 (m, 2H), 3.94 ± 3.93 (m, 4H),
3.29 (dd, J ˆ 10.8, 3.1 Hz, 2H), 1.95 (s, 12H), 1.94 ± 1.82 (m, 2H), 1.77 ± 1.51
(m, 4H), 1.47 ± 1.27 (m, 10H), 0.91 (t, J ˆ 6.7 Hz, 6H); 13C NMR (CDCl3,
75 MHz): d ˆ 85.67, 70.00, 68.03, 67.77, 67.59, 63.04, 40.48, 32.21, 31.43, 27.19,
22.75, 14.15 (dl); 85.82, 69.87, 67.82, 67.65, 67.51, 31.47 (meso, separated
(51), 242 (22), 162 (20), 147 (24), 56 (26); C16H24FeN2 (300.23): calcd C
64.01, H 8.06, N 9.33; found C 63.91, H 8.13, N 9.16.
(R,R)-1,1'-Bis(a-N-methylamino-b-methylpropyl)ferrocene (19b): The di-
acetate 12e (230 mg, 0.55 mmol) was treated with methylamine (40% in
water, 2 mL) in MeOH/water. Chromatography (ether with 1% NEt3) gave
the diastereomerically pure diamine 19b (40 mg, 20%). Yellow solid; m.p.
79 ± 808C; [a]d ˆ 91.3 (c ˆ 0.78, CHCl3); IR (KBr): nÄmax ˆ 3346 (w), 3091
(w), 2952 (s), 1431 (s), 1363 (m), 1101 (s), 820 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 4.14 (s, 2H), 4.01 ± 3.97 (m, 6H), 3.00 (d, J ˆ 3.6 Hz, 2H),
2.52 (s, 6H), 2.00 ± 1.84 (m, 4H), 0.73 (d, J ˆ 6.8 Hz, 12H); 13C NMR
(CDCl3, 75 MHz): d ˆ 90.84, 69.04, 67.32, 66.99, 66.75, 65.22, 35.70, 29.66,
‡
19.76, 16.18; MS (EI, 70 eV): m/z (%): 356 (M , 11), 325 (9), 282 (100), 135
‡
signals); MS (EI, 70 eV): m/z (%): 440 (M , 21), 395 (25), 369 (22), 352 (27),
324 (22), 281 (56), 178 (38), 149 (100), 135 (24); C26H44FeN2 (440.49): calcd
C 70.89, H 10.07, N 6.36; found C 70.68, H 10.09, N 6.40.
(27); C20H32FeN2 (356.33): calcd C 67.41, H 9.05, N 7.86; found C 67.67, H
9.05, N 7.73. The meso-isomer (meso-19b) was also obtained (11 mg, 6%).
Yellow oil; IR (KBr): nÄmax ˆ 3353 (w), 3091 (w), 2955 (s), 2786 (m), 1467
(m), 1380 (m), 818 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.15 ± 4.14 (m,
2H), 4.04 ± 4.01 (m, 6H), 3.01 (d, J ˆ 3.5 Hz, 2H), 2.55 (s, 6H), 2.01 ± 1.90
(m, 4H), 0.76 (d, J ˆ 6.9 Hz, 6H), 0.64 (d, J ˆ 6.7 Hz, 6H); 13C NMR
(CDCl3, 75 MHz): d ˆ 91.01, 69.07, 67.42, 67.03, 66.75, 65.24, 35.71, 29.79,
(R,R)-1,1'-Bis(a-N,N-dimethylaminophenylmethyl)ferrocene (17c): The
diacetate 12e (265 mg, 0.55 mmol) was treated with dimethylamine (40%
in water, 2 mL) in THF/water. Chromatography (hexanes/MTBE 3:1 with
1% NEt3) gave the diamine 17c (234 mg, 94%, dl:meso ˆ 91:9). Yellow
‡
solid; m.p. 49 ± 508C; [a]d ˆ ‡103.5 (c ˆ 2.40, CHCl3); IR (film): nÄmax
ˆ
19.80, 16.36; MS (EI, 70 eV): m/z (%): 356 (M , 7), 325 (15), 282 (100), 162
3060 (w), 3030 (w), 2950 (m), 2860 (w), 2810 (w), 2770 (s), 1455 (s), 1300
(m), 1005 (s), 830 (m), 740 (s), 700 (m); 1H NMR (CDCl3, 300 MHz): d ˆ
7.41 ± 7.26 (m, 10H), 3.89 ± 3.88 (m, meso)/3.87 ± 3.86 (m, dl, 2H total), 3.58
(s, dl)/3.57 ± 3.54 (m)/3.50 ± 3.46 (m)/3.43 (s, meso, 8H total), 1.97 (s, dl)/1.94
(s, meso, 12H total); 13C NMR (CDCl3, 75 MHz): d ˆ 143.24, 128.23, 127.83,
126.85, 90.26, 72.23, 71.22, 69.95, 67.58, 67.52, 44.38 (dl); 143.43, 128.35,
127.87, 126.89, 71.97, 71.67, 69.14, 67.70, 67.08, 44.27 (meso, separated
(18), 135 (35); C20H32FeN2 (356.33): calcd C 67.41, H 9.05, N 7.86; found C
67.56, H 9.03, N 7.83. As a second by-product (6R,8S)-6,8-diisopropyl-7-
methyl-7-aza[3]ferrocenophane (21a) was found (99 mg, 55%, cis:trans ˆ
88:12). Yellow oil; IR (film): nÄmax ˆ 3080 (w), 2900 (s), 1450 (m), 1365 (m),
1
1015 (m), 800 (m); H NMR (CDCl3, 300 MHz): d ˆ 4.13 ± 3.91 (m, 10H),
2.46 (s, trans)/2.43 (s, cis, 3H total), 1.94 ± 1.76 (m, 2H), 1.02 (d, J ˆ 6.4 Hz,
6H), 0.75 (d, J ˆ 6.5 Hz)/0.71 (d, J ˆ 6.9 Hz, 6H total); 13C NMR (CDCl3,
75 MHz): d ˆ 92.82, 72.17, 69.45, 69.11, 67.84, 66.47, 30.61, 28.52, 21.61, 21.26
(cis); 91.98, 38.41 (trans, separated signals); MS (EI, 70 eV): m/z (%): 325
‡
signals); MS (EI, 70 eV): m/z (%): 452 (M , 33), 407 (13), 365 (100), 211
(55); C28H32FeN2 (452.42): calcd C 74.33, H 7.13, N 6.19; found C 74.23, H
7.10, N 6.05.
‡
(M , 34), 282 (100), 135 (12); C19H27FeN (325.28): calcd C 70.16, H 8.37, N
4.31; found C 70.30, H 8.53, N 4.44.
(R,R)-1,1'-Bis(a-N,N-dimethylamino(2-naphthyl)methyl)ferrocene (17d):
The diacetate 12g (3.07 g, 5.28 mmol) was treated with dimethylamine
(40% in water, 10 mL) in THF/water. Chromatography (hexanes/MTBE
3:1 with 1% NEt3) gave the diamine 17d (2.48 g, 85%, dl:meso ˆ 82:18).
One recrystallization from hexanes/ether gave dl:meso ˆ 95:5. Yellow
(R,R)-1,1'-Bis(a-N-methylaminophenylmethyl)ferrocene (19c): The diac-
etate 12e (0.40 g, 0.83 mmol) was treated with methylamine (40% in water,
2 mL) in THF/water. Chromatography (hexanes/MTBE 3:1 with 1% NEt3)
gave the diamine 19c (250 mg, 71%, dl:meso ˆ 92:8). Yellow solid; m.p.
129 ± 1308C; [a]d ˆ ‡56.2 (c ˆ 0.63, CHCl3); IR (KBr): nÄmax ˆ 3083 (w),
2944 (w), 2871 (w), 1492 (m), 1124 (m), 1022 (m), 823 (m), 730 (m), 698 (s);
1H NMR (CDCl3, 300 MHz): d ˆ 7.38 ± 7.25 (m, 10H), 4.33 ± 4.24 (m, 4H),
4.08 ± 3.99 (m, 6H), 2.38 (s, meso)/2.37 (s, dl, 6H total), 2.07 (s, 2H); 13C
NMR (CDCl3, 75 MHz): d ˆ 143.58, 128.25, 127.52, 127.08, 93.70, 68.15,
67.78, 67.65, 66.87, 64.63, 34.80 (dl); 142.42, 93.86, 68.22, 67.91, 66.72, 34.92
solid; m.p. 141 ± 1428C; [a]d ˆ 47.1 (c ˆ 0.47, CHCl3); IR (KBr): nÄmax
ˆ
3058 (w), 2979 (w), 2944 (w), 2810 (m), 2762 (s), 1296 (m), 1011 (s), 828 (s),
1
762 (m); H NMR (CDCl3, 300 MHz): d ˆ 7.95 ± 7.41 (m, 14H), 3.96 ± 3.95
(m, 2H), 3.75 (s, dl)/3.59 (s)/3.56 (s, meso)/3.52 (s, meso)/3.50 (s, meso)/3.42
(s, dl, 8H total), 2.00 (s, dl)/1.92 (s, meso, 12H total); 13C NMR (CDCl3,
75 MHz): d ˆ 140.74, 133.16, 132.70, 127.90, 127.67, 127.50, 126.78, 126.65,
125.90, 125.52, 90.37, 72.23, 70.98, 70.06, 68.10, 67.67, 44.52 (dl); 140.92,
133.26, 132.81, 127.05, 126.97, 126.00, 90.18, 71.89, 69.03, 67.17, 44.32 (meso,
‡
(meso, separated signals); MS (EI, 70 eV): m/z (%): 424 (M , 15), 393 (100),
364 (16), 211 (33), 196 (19), 153 (21); C26H28FeN2 (424.37): calcd C 73.59, H
6.65, N 6.60; found C 73.80, H 6.76, N 6.34.
‡
separated signals); MS (EI, 70 eV): m/z (%): 552 (M , 31), 507 (21), 465
(100), 261 (78), 232 (41), 203 (32), 184 (28); C36H36FeN2 (552.54): calcd C
78.26, H 6.57, N 5.07; found C 77.98, H 6.86, N 4.87.
(R,R)-1,1'-Bis(a-N-methylaminophenylmethyl)ruthenocene (20): The di-
acetate 13 (330 mg, 0.63 mmol) was treated with methylamine (40% in
water, 2 mL) in THF/water. Chromatography (MTBE with 1% NEt3) gave
the diamine 20 (187 mg, 64%, dl:meso ˆ 95:5). Pale yellow solid; m.p.
151 ± 1518C; [a]d ˆ 74.2 (c ˆ 0.55, CHCl3); IR (KBr): nÄmax ˆ 3311 (w),
3082 (w), 2942 (m), 2780 (m), 1432 (m), 730 (s), 698 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 7.30 ± 7.15 (m, 10H), 4.57 ± 4.56 (m, 2H), 4.47 ± 4.46 (m, 2H),
4.37 ± 4.34 (m, 4H), 4.00 (s, 2H), 2.24 (s, 6H), 1.70 (s, 2H); 13C NMR
(CDCl3, 75 MHz): d ˆ 143.15, 127.93, 127.16, 126.80, 98.26, 70.49, 70.18,
(R,R)-1,1'-Bis(a-N,N-dimethylaminophenylmethyl)ruthenocene (18): The
diacetate 13 (0.60 g, 1.14 mmol) was treated with dimethylamine (40% in
water, 5 mL) in THF/water. Chromatography (hexanes/MTBE 3:1 with
1% NEt3) gave the diamine 18 (526 mg, 93%, dl:meso ˆ 93:7). Pale yellow
solid; m.p. 141 ± 1428C; [a]d ˆ ‡10.0 (c ˆ 0.24, CHCl3); IR (KBr): nÄmax
ˆ
3080 (w), 2939 (w), 2771 (m), 1450 (m), 1007 (m), 814 (m), 724 (s), 701 (s);
1H NMR (CDCl3, 300 MHz): d ˆ 7.25 ± 7.12 (m, 10H), 4.25 ± 4.24 (m)/3.90 ±
3.89 (m, meso)/3.87 ± 3.86 (m, dl)/3.81 ± 3.79 (m, 8H total), 3.32 (s, dl)/3.19
(s, meso, 2H total), 2.00 (s, dl)/1.99 (s, meso, 12H total); 13C NMR (CDCl3,
75 MHz): d ˆ 145.05, 127.86, 127.71, 126.71, 95.35, 74.18, 72.48, 72.27, 70.54,
70.18, 45.06 (dl); 145.17, 127.99, 126.73, 95.31, 74.55, 72.05, 71.72, 70.81,
‡
70.00, 69.57, 63.67, 34.58; MS (EI, 70 eV): m/z (%): 469 (M , 1), 438 (100),
410 (28), 348 (15), 319 (15), 219 (25), 118 (79); C26H28N2Ru (469.59): calcd C
66.50, H 6.01, N 5.97; found C 66.60, H 5.95, N 6.13.
(R,R)-1,1'-Bis(a-N-benzylaminoethyl)ferrocene (19d): The diacetate 12a
(2.08 g, 5.80 mmol) was treated with benzylamine (3 mL) in THF/water.
Chromatography (MTBE with 1% NEt3) gave the diamine 19d (2.04 g,
78%, dl:meso >97:3). Yellow oil; [a]d ˆ 97.6 (c ˆ 0.71, CHCl3); IR (film):
nÄmax ˆ 3070 (w), 3030 (w), 2970 (m), 2840 (w), 1455 (s), 1370 (m), 830 (m),
740 (s), 698 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.40 ± 7.28 (m, 10H),
4.18 ± 4.16 (m, 4H), 4.12 ± 4.10 (m, 4H), 3.93 (d, J ˆ 13.2 Hz, 2H), 3.83 (d,
J ˆ 13.1 Hz, 2H), 3.60 (q, J ˆ 6.5 Hz, 2H), 1.61 (s, 2H), 1.46 (d, J ˆ 6.5 Hz,
6H); 13C NMR (CDCl3, 75 MHz): d ˆ 140.62, 128.26, 127.97, 126.71, 93.80,
67.74, 67.41, 66.19, 51.24, 51.14, 21.52 (dl); 67.85, 67.35, 66.25 (meso,
69.73, 44.97 (meso, separated signals); MS (EI, 70 eV): m/z (%): 453
‡
([M
NMe2], 20), 410 (100), 319 (7), 257 (9), 205 (11), 166 (21), 134 (32);
C28H32N2Ru (497.64): calcd C 67.58, H 6.48, N 5.63; found C 67.23, H 6.70, N
5.33.
(R,R)-1,1'-Bis(a-N-methylaminoethyl)ferrocene (19a): The diacetate 12a
(440 mg, 1.23 mmol) was treated with methylamine (40% in water, 3 mL)
in MeOH/water. The crude diamine 19a (390 mg, 90% pure (95%),
dl:meso ˆ 97:3) could not be purified further. Yellow oil; [a]d ˆ 5.7 (c ˆ
1.73, CHCl3); IR (film): nÄmax ˆ 3260 (m), 3080 (w), 2930 (s), 2790 (m), 1440
(m), 1370 (w), 1310 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 3.95 (t, J ˆ
1.8 Hz, 4H), 3.90 (t, J ˆ 1.8 Hz, 4H), 3.25 (q, J ˆ 6.5 Hz, 2H), 2.25 (s, 6H),
1.34 (s, 2H), 1.20 (d, J ˆ 6.5 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ
93.25, 67.80, 67.71, 67.48, 65.70, 53.58, 33.77, 20.79 (dl); 93.50 (meso,
‡
separated signals); MS (EI, 70 eV): m/z (%): 452 (M , 17), 345 (100), 330
(25), 254 (28), 239 (33), 162 (19), 91 (52); C28H32FeN2 (452.42): calcd C
74.34, H 7.13, N 6.19; found C 74.45, H 6.92, N 6.28. As a minor by-product
(6R,8S)-7-benzyl-6,8-dimethyl-7-aza[3]ferrocenophane (21b) was found.
Yellow solid; m.p. 88 ± 898C; IR (KBr): nÄmax ˆ 3077 (w), 2960 (m), 2880 (m),
‡
separated signal); MS (EI, 70 eV): m/z (%): 300 (M , 19), 269 (100), 254
Chem. Eur. J. 1998, 4, No. 5
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0963 $ 17.50+.25/0
963

P. Knochel, L. Schwink
FULL PAPER
1453 (m), 1372 (m), 1135 (m), 1020 (m), 733 (s), 703 (m); 1H NMR (CDCl3,
300 MHz): d ˆ 7.48 ± 7.46 (m, 2H), 7.36 ± 7.31 (m, 2H), 7.25 ± 7.20 (m, 1H),
4.19 ± 4.17 (m, 2H), 4.13 ± 4.06 (m, 8H), 3.49 (q, J ˆ 7.1 Hz, 2H), 1.30 (d, J ˆ
7.2 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 142.66, 128.16, 127.74, 126.49,
91.37, 69.84, 68.64, 68.57, 67.72, 53.73, 51.82, 18.35; MS (EI, 70 eV): m/z (%):
iPrOH, 1.0 mLmin 1, 254 nm): tR/min ˆ 8.56 (SS), 9.38 (RS), 9.96 (RR);
[a]d ˆ ‡28.6 (c ˆ 1.63, CHCl3); IR (film): nÄmax ˆ 3080 (w), 2950 (vs), 2860
(s), 1050 (vs), 825 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 4.72 ± 4.68 (m,
2H), 4.16 (s, 2H), 4.10 (s, 6H), 3.91 ± 3.85 (m, 2H), 3.81 ± 3.74 (m, 2H),
2.22 ± 2.15 (m, 2H), 1.95 ± 1.84 (m, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ
89.38, 77.16, 68.61, 68.61, 68.54, 68.47, 68.00, 66.30, 32.32, 26.21; MS (EI,
‡
345 (M , 100), 330 (40), 238 (37), 212 (19); C21H23FeN (345.27): calcd C
73.05, H 6.71, N 4.06; found C 73.22, H 6.75, N 4.24.
‡
70 eV): m/z (%): 326 (M , 100), 255 (16), 135 (13), 121 (12); C18H22FeO2
(326.22): calcd C 66.27, H 6.80; found C 66.41, H 6.91.
(R,R)-1,1'-Bis(a-N-benzylaminophenylmethyl)ferrocene (19e): The diac-
etate 12e (1.27 g, 2.63 mmol) was treated with benzylamine (5 mL) in THF/
water. Chromatography (hexanes/ether 2:1 with 1% NEt3) gave the
diastereomerically pure diamine 19e (1.31 g, 86%). Yellow solid; m.p.
118 ± 1208C; [a]d ˆ 39.5 (c ˆ 0.59, CHCl3); IR (KBr): nÄmax ˆ 3070 (w),
3030 (w), 2970 (s), 2820 (m), 1450 (s), 1205 (m), 1085 (m), 830 (m), 700 (s);
1H NMR (CDCl3, 300 MHz): d ˆ 7.41 ± 7.26 (m, 20H), 4.46 (s, meso)/4.39 (s,
dl, 2H total), 4.28 ± 4.27 (m, dl)/4.20 ± 4.19 (m, 2H total), 4.00 ± 3.92 (m,
6H), 3.78 (d, J ˆ 13.3 Hz, 2H), 3.58 (d, J ˆ 13.3 Hz)/3.56 (d, J ˆ 13.3 Hz, 2H
total), 2.14 (s, 2H); 13C NMR (CDCl3, 75 MHz): d ˆ 143.80, 140.59, 128.40,
128.27, 127.53, 127.05, 126.91, 94.04, 68.11, 67.84, 67.69, 66.31, 61.03, 51.53
(dl); 94.15, 66.44, 61.13, 51.59 (meso, separated signals); MS (EI, 70 eV): m/
(R,R)-1,1'-Bis(N-methyl-2-pyrrolidinon-5-yl)ferrocene (24a): The diace-
tate 4g (420 mg, 0.84 mmol) was treated with methylamine (40% in water,
6 mL) in MeOH/water according to general procedure E. Chromatography
(CH2Cl2/MeOH 10:1) gave the dipyrrolidinone 24a (90 mg, 28%), which
was directly reduced to the dipyrrolidine 25a (see below). Yellow oil;
[a]d ˆ ‡327.5 (c ˆ 0.91, CHCl3); 1H NMR (CDCl3, 300 MHz): d ˆ 4.24 ±
4.04 (m, 10H), 2.53 (s, 6H), 2.49 ± 2.09 (m, 8H); 13C NMR (CDCl3,
75 MHz): d ˆ 173.90, 87.32, 70.08, 69.66, 68.64, 66.64, 59.19, 30.45, 27.41,
25.80.
(R,R)-1,1'-Bis(N-benzyl-2-pyrrolidinon-5-yl)ferrocene (24b): The diace-
tate 4g (260 mg, 0.52 mmol) was treated with benzylamine (2 mL) in
MeOH/water according to general procedure E. Chromatography (CH2Cl2/
MeOH 40:1) gave the dipyrrolidinone 24b (210 mg, 76%, dl:meso ˆ 92:8).
Yellow oil; [a]D ˆ ‡168.9 (c ˆ 0.74, CHCl3); IR (KBr): nÄmax ˆ 3083 (w),
3029 (w), 2920 (m), 1682 (vs), 1413 (m), 1242 (m), 702 (m); 1H NMR
(CDCl3, 300 MHz): d ˆ 7.31 ± 7.21 (m, 6H), 7.10 ± 7.08 (m, 4H), 4.88 (d, J ˆ
15.1 Hz, 2H), 4.20 ± 4.03 (m, 8H), 3.91 ± 3.90 (m, 2H), 3.48 (d, J ˆ 15.1 Hz,
2H), 2.60 ± 2.15 (m, 8H); 13C NMR (CDCl3, 75 MHz): d ˆ 173.82, 136.36,
128.21, 127.58, 126.98, 86.77, 70.46, 69.56, 68.36, 65.98, 55.93, 43.22, 30.48,
25.73 (dl); 70.33 (meso, separated signal); MS (EI, 70 eV): m/z (%): 532
‡
z (%): 576 (M , 64), 469 (100), 378 (51), 289 (17), 211 (69), 91 (100);
C38H36FeN2 (576.56): calcd C 79.16, H 6.29, N 4.86; found C 78.75, H 6.48, N
4.51.
(R,R)-1,1'-Bis(a-N-phenylaminoethyl)ferrocene (19 f): The diacetate 12a
(344 mg, 0.97 mmol) was treated with aniline (2 mL) in MeOH/water.
Chromatography (hexanes/ether 10:1) gave the diastereomerically pure
diamine 19 f (369 mg, 90%). Yellow oil; [a]d ˆ ‡9.6 (c ˆ 0.95, CHCl3); IR
(film): nÄmax ˆ 3380 (m), 2970 (m), 1595, 1490 (s), 1425 (m), 1310 (s), 825 (m),
745 (s), 690 (m); 1H NMR (CDCl3, 300 MHz): d ˆ 7.34 ± 7.29 (m, 4H),
6.86 ± 6.75 (m, 6H), 4.50 ± 4.23 (m, 10H), 4.02 (s, 2H), 1.62 (d, J ˆ 6.4 Hz,
6H); 13C NMR (CDCl3, 75 MHz): d ˆ 147.37, 129.33, 117.30, 113.36, 93.88,
68.26, 68.00, 67.44, 66.59, 47.24, 21.09 (dl); 113.27, 67.20, 66.81, 21.21 (meso,
‡
(M , 100), 294 (64), 91 (47); C32H32FeN2O2 (532.46): calcd C 72.18, H 6.06,
N 5.26; found C 71.89, H 6.18, N 5.13.
(R,R)-1,1'-Bis(N-methyl-2-pyrrolidinyl)ferrocene (25a): LiAlH4 reduction
of 24a (70 mg, 0.18 mmol) afforded 25a (53 mg, 84%, dl:meso 87:13).
Yellow oil; [a]d ˆ ‡152.9 (c ˆ 0.34, CHCl3); IR (film): nÄmax ˆ 3080 (w), 2910
(s), 2760 (s), 1450 (m), 1210 (m), 1040 (m), 820 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 4.14 ± 4.00 (m, 8H), 3.07 ± 3.02 (m, 2H), 2.84 (t, J ˆ 8.2 Hz,
2H), 2.25 ± 2.14 (m, 4H), 2.13 (s, 6H), 2.05 ± 1.72 (m, 6H); 13C NMR
(CDCl3, 75 MHz): d ˆ 88.13, 70.38, 68.95, 67.94, 66.02, 65.50, 57.44, 40.00,
32.04, 22.32 (dl); 70.25, 68.82, 67.80, 65.40, 35.13 (meso, separated signals);
‡
separated signals); MS (EI, 70 eV): m/z (%): 424 (M , 15), 331 (31), 239
(100), 147 (27), 93 (20); C26H28FeN2 (424.37): calcd C 73.59, H 6.65, N 6.60;
found C 73.61, H 6.86, N 6.39.
General procedure F for debenzylation of amines 19d,e: The dibenzylated
diamine (0.85 mmol) was dissolved in MeOH (5 mL). Pd(OH)2 (20 mg,
10% on C) and one drop of formic acid were added. The flask was
connected to vacuum and purged twice with argon. After evacuating a third
time the flask was purged with hydrogen from a balloon and stirred rapidly
for 12 h. The catalyst was removed by filtration (Celite, 5 cm). The filtrate
was concentrated and taken into ether (30 mL) and 10% aqueous NaOH
(20 mL). The organic layer was washed with brine (20 mL), dried, and
evaporated to provide a quantitative yield of the deprotected amine 22.
‡
MS (EI, 70 eV): m/z (%): 352 (M , 41), 321 (34), 294 (43), 268 (100), 205
(62), 148 (24), 121 (20), 84 (80); C20H28FeN2 (352.30): calcd C 68.19, H 8.01,
N 7.95; found C 67.94, H 7.98, N 8.15.
(R,R)-1,1'-Bis(N-benzyl-2-pyrrolidinyl)ferrocene (25b): The diacetate 12c
(250 mg, 0.52 mmol) was treated with benzylamine (2 mL) in MeOH/water
according to general procedure E. Chromatography (hexanes/MTBE 1:1
with 5% NEt3) gave the dipyrrolidine 25b (248 mg, 95%, dl:meso ˆ 92:8).
LiAlH4 reduction of 24b (197 mg, 0.37 mmol) also afforded 25b (114 mg,
61%). Yellow solid; m.p. 124 ± 1268C; [a]D ˆ ‡153.6 (c ˆ 0.74, CHCl3); IR
(KBr): nÄmax ˆ 3058 (s), 3027 (w), 2936 (vs), 2781 (s), 1453 (m), 1107 (m),
1027 (m), 821 (m), 697 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.25 ± 7.13 (m,
10H), 4.22 ± 4.21 (m, 2H), 4.12 ± 4.11 (m, 2H), 4.07 ± 4.06 (m, 4H), 3.92 (d,
J ˆ 12.8 Hz, 2H), 3.24 (t, J ˆ 7.9 Hz, 2H), 2.99 (d, J ˆ 12.8 Hz, 2H), 2.89 ±
2.83 (m, 2H), 2.35 ± 2.00 (m, 6H), 1.80 ± 1.70 (m, 4H); 13C NMR (CDCl3,
75 MHz): d ˆ 139.86, 128.72, 127.96, 126.50, 89.11, 70.45, 68.88, 67.76, 66.56,
63.67, 57.87, 53.84, 32.42, 22.25 (dl); 67.63, 63.55 (meso, separated signals);
(R,R)-1,1'-Bis(a-aminoethyl)ferrocene (22a): The dibenzylated diamine
19d (1.10 g, 2.43 mmol) afforded on debenzylation the diamine 22a
(664 mg, ca. 90% pure by NMR analysis). Attempts to further purify the
amine by chromatography were not successful. Yellow oil; 1H NMR
(CDCl3, 300 MHz): d ˆ 4.13 ± 4.07 (m, 8H), 3.82 ± 3.78 (m, 2H), 1.72 (s,
4H), 1.31 (d, J ˆ 6.4 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 96.55, 67.79,
67.72, 66.00, 65.91, 45.90, 25.01.
(R,R)-1,1'-Bis(a-aminophenylmethyl)ferrocene (22b): The dibenzylated
diamine 19e (1.17 g, 2.03 mmol) afforded on debenzylation the diamine
22b (802 mg, 99%, dl:meso ˆ 96:4). Yellow solid; m.p. 88 ± 908C; [a]d ˆ
‡29.6 (c ˆ 2.39, CHCl3); IR (KBr): nÄmax ˆ 3391 (w), 3078 (w), 3062 (w),
2853 (m), 1598 (m), 1490 (m), 1450 (m), 1026 (w), 831 (m), 710 (s); 1H NMR
(CDCl3, 300 MHz): d ˆ 7.35 ± 7.21 (m, 10H), 4.86 (s, 2H), 4.35 ± 4.32 (m,
2H), 4.17 ± 4.05 (m, 6H), 1.95 (s, 4H); 13C NMR (CDCl3, 75 MHz): d ˆ
145.72, 128.18, 126.56, 94.58, 68.21, 67.71, 67.51, 66.37, 55.22; MS (EI, 70 eV):
‡
MS (EI, 70 eV): m/z (%): 504 (M , 60), 413 (18), 344 (25), 281 (46), 253
(15), 189 (23), 160 (32), 91 (100); C32H36FeN2 (504.50): calcd C 76.19, H 7.19,
N 5.55; found C 75.94, H 6.99, N 5.43.
(R,R)-1,1'-Bis(2-pyrrolidinyl)ferrocene (26): The dibenzylated diamine
25b (100 mg, 0.20 mmol) was deprotected according to general procedure
F to afford quantitatively the dipyrrolidine 26 (66 mg, >90% pure). Yellow
‡
m/z (%): 396 (M , 17), 379 (100), 364 (9), 290 (20), 224 (23), 153 (33);
C24H24FeN2 (396.31): calcd C 72.74, H 6.10, N 7.07; found C 72.70, H 6.10, N
6.93.
1
oil; [a]d ˆ ‡9.4 (c ˆ 0.44, CHCl3); H NMR (CDCl3, 200 MHz): d ˆ 4.14 ±
4.07 (m, 8H), 3.87 ± 3.81 (m, 2H), 3.13 ± 3.07 (m, 2H), 2.93 ± 2.86 (m, 2H),
2.13 ± 2.03 (m, 4H), 1.87 ± 1.56 (m, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ
92.43, 67.89, 67.86, 67.33, 66.56, 57.58, 46.85, 33.11, 25.79; C18H24FeN2
(324.25): calcd C 66.68, H 7.46, N 8.64; found C 66.30, H 7.39, N 8.46.
(R,R)-1,1'-Bis(2-tetrahydrofuranyl)ferrocene (23): The diol 4e (113 mg,
0.28 mmol) was dissolved in THF (5 mL) at 08C and nBuLi (1.4m in
hexanes, 0.5 mL) was added dropwise. After 30 min at 08C the solution was
gradually warmed to 408C and stirred for 2 h. The reaction was poured into
saturated aqueous NH4Cl (20 mL) and extracted with ether (30 mL). The
organic layer was washed with water (2 Â 20 mL) and brine (15 mL), then
dried and concentrated to give an oil which was purified by column
chromatography (hexanes/MTBE 3:1) to afford the bis(tetrahydrofuran)
23 (77 mg, 85%, dl:meso ˆ 91:9, 99.5% ee). Yellow oil; HPLC (OD, 10%
General procedure
G for diphosphines 27 and 28: The diacetate
(0.46 mmol) was dissolved in acetic acid (4 mL) under argon. Diphenyl-
phosphine (930 mg, 5 mmol) was added and the reaction heated to 408C for
3 h. The solid that formed was evaporated in vacuum (0.7 mmHg, 2 h) and
dissolved in THF (10 mL). An excess of BH3 ´ SMe2 (10m, 0.8 mL) was
964
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0964 $ 17.50+.50/0
Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
added and the mixture stirred for 1 h at room temperature. Unreacted
borane was destroyed by slow addition of MeOH (2 mL; caution: gas
evolution!). After concentration to 2 mL the crude reaction mixture was
directly purified by column chromatography (CH2Cl2/hexanes 1:1) to
provide the diphosphine complexed to borane.
(1.55 g, 7.0 mmol). Chromatography (hexanes/ethyl acetate 2:1) afforded
the aminophosphine 30a (200 mg, 29%). Yellow solid; [a]d ˆ 435 (c ˆ
1.0, CHCl3); IR (KBr): nÄmax ˆ 3050 (w), 2930 (w), 2770 (m), 1432 (m), 1094
(m), 739 (m), 696 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.42 ± 7.37 (m, 4H),
7.30 ± 7.20 (m, 16H), 4.45 ± 4.44 (m, 2H), 4.25 ± 4.24 (m, 2H), 4.20 ± 4.16 (m,
2H), 3.15 ± 3.14 (m, 2H), 1.80 (s, 12H), 1.35 (d, J ˆ 6.7 Hz, 6H); 13C NMR
(CDCl3, 75 MHz): d ˆ 140.87 (d, J ˆ 7.2 Hz), 138.30 (d, J ˆ 9.4 Hz), 134.71
(d, J ˆ 22.0 Hz), 131.96 (d, J ˆ 7.2 Hz), 128.39, 127.72 (d, J ˆ 7.7 Hz), 127.05
(d, J ˆ 6.8 Hz), 126.77, 98.17 (d, J ˆ 23.0 Hz), 76.74 (d, J ˆ 9.4 Hz), 72.63 (d,
J ˆ 6.0 Hz), 72.43 (d, J ˆ 4.1 Hz), 70.70 (d, J ˆ 3.7 Hz), 56.53 (d, J ˆ 7.0 Hz),
38.64, 8.78; 31P NMR (CDCl3, 162 MHz): d ˆ 23.1; MS (EI, 70 eV): m/z
(R,R)-1,1'-Bis(a-(diphenylphosphino)phenylmethyl)ferrocene (diborane
complex) (27): The diacetate 12e (220 mg, 0.46 mmol) was treated with
diphenylphosphine (930 mg, 5.0 mmol) to provide the protected diphos-
phine 27 (244 mg, 70%). Yellow solid; m.p. 242 ± 2448C; [a]d ˆ 63.5 (c ˆ
0.05, CHCl3); IR (KBr): nÄmax ˆ 3054 (w), 3027 (w), 2401 (s), 1436 (s), 1065
(s), 739 (s); 1H NMR (CDCl3, 200 MHz): d ˆ 7.65 ± 7.14 (m, 30H), 4.31 (d,
J ˆ 14.9 Hz, 2H), 3.64 ± 3.63 (m, 2H), 3.41 ± 3.38 (m, 4H), 3.11 ± 3.10 (m,
2H), 2.0 ± 0.0 (s, 6H); 13C NMR (CDCl3, 100 MHz): d ˆ 137.23, 133.92 (d,
J ˆ 8.5 Hz), 132.78 (d, J ˆ 8.2 Hz), 131.24 (d, J ˆ 2.1 Hz), 130.79 (d, J ˆ
2.2 Hz), 130.01 (d, J ˆ 5.4 Hz), 128.61 (d, J ˆ 5.2 Hz), 128.24 (d, J ˆ
14.5 Hz), 118.14 (d, J ˆ 14.5 Hz), 127.98, 127.69 (d, J ˆ 53 Hz), 127.33 (d,
J ˆ 1.5 Hz), 84.99 (d, J ˆ 3.8 Hz), 70.84 (d, J ˆ 1.1 Hz), 69.62 (d, J ˆ 1.0 Hz),
‡
(%): 696 (M , 45), 651 (25), 636 (100), 608 (17), 574 (31), 466 (40), 325 (18),
72 (46). Value of optical rotation and 1H NMR data are in good agreement
with literature data.[28]
(aR,a'R)-2,2'-Bis(a-N,N-dimethylaminohexyl)-(S,S)-1,1'-bis(diphenyl-
phosphino)ferrocene (30b): Diamine 17b (169 mg, 0.38 mmol) was lithi-
ated (tBuLi, 2.3 mmol, 18 h) and treated with diphenylchlorophosphine
(880 mg, 4.0 mmol). Chromatography (hexanes/MTBE 15:1 with 1%
NEt3) afforded the diastereomerically pure aminophosphine 30b
(122 mg, 39%, > 96% ee). Yellow solid; m.p. 189 ± 1918C; HPLC (OD,
1% iPrOH, 1.0 mL/min, 254 nm): tR/min ˆ 3.69 (aRa'R,SS), 3.91
(aSa'S,RR); [a]d ˆ 357 (c ˆ 0.78, CHCl3); IR (KBr): nÄmax ˆ 3069 (w),
3050 (w), 2925 (s), 2854 (w), 2821 (w), 2776 (w), 1432 (s), 824 (w), 735 (m),
696 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.25 ± 7.03 (m, 20H), 4.39 ± 4.38
(m, 2H), 4.08 ± 4.06 (m, 2H), 3.90 ± 3.86 (m, 2H), 2.93 (s, 2H), 2.00 ± 1.92
(m, 2H), 1.88-1.78 (m, 2H), 1.77 (s, 12H), 1.55 ± 1.20 (m, 12H), 0.93 (t, J ˆ
6.5 Hz, 6H); 13C NMR (CDCl3, 75 MHz): d ˆ 140.60 (d, J ˆ 6.9 Hz), 138.39
(d, J ˆ 9.0 Hz), 134.94 (d, J ˆ 22.4 Hz), 132.04 (d, J ˆ 18.7 Hz), 128.49,
127.89 (d, J ˆ 8.0 Hz), 127.17 (d, J ˆ 6.6 Hz), 126.91, 98.26 (d, J ˆ 24.0 Hz),
76.24 (d, J ˆ 8.8 Hz), 73.02 (d, J ˆ 5.0 Hz), 72.11 (d, J ˆ 5.5 Hz), 70.63, 61.04
(d, J ˆ 7.4 Hz), 39.61, 32.75, 30.71, 28.62, 22.79, 14.14; 31P NMR (CDCl3,
69.36, 68.19, 47.10 (d, J ˆ 26.7 Hz); 31P NMR (CDCl3, 162 MHz): d ˆ 24.4;
‡
MS (EI, 70 eV): m/z (%): 733 ([M
2BH3], 9), 549 (100), 395 (53), 364
(57), 183 (32); C48H46B2FeP2 (762.31): calcd C 75.63, H 6.35; found C 75.26,
H 6.66.
(R,R)-1,1'-Bis(a-(diphenylphosphino)phenylmethyl)ruthenocene (dibor-
ane complex) (28): The diacetate 13 (396 mg, 0.75 mmol) was treated with
diphenylphosphine (930 mg, 5.0 mmol) to provide the protected diphos-
phine 28 (204 mg, 34%). Pale yellow solid; m.p. >2608C; [a]d ˆ ‡11.3 (c ˆ
0.16, CHCl3); IR (KBr): nÄmax ˆ 3059 (w), 3026 (w), 2874 (w), 2399 (vs), 1435
(s), 1105 (m), 1067 (s), 815 (m), 738 (s), 692 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 7.52 ± 7.10 (m, 30H), 4.15 (d, J ˆ 15.5 Hz, 2H), 4.13 ± 4.12 (m,
2H), 3.80 ± 3.79 (m, 2H), 3.76 ± 3.75 (m, 2H), 3.59 ± 3.58 (m, 2H), 1.50 ± 0.50
(s, 6H); 13C NMR (CDCl3, 100 MHz): d ˆ 138.78, 133.68 (d, J ˆ 8.4 Hz),
132.85 (d, J ˆ 8.3 Hz), 131.16 (d, J ˆ 2.2 Hz), 130.82 (d, J ˆ 2.2 Hz), 129.71
(d, J ˆ 5.2 Hz), 128.74 (d, J ˆ 14.1 Hz), 128.50 (d, J ˆ 9.7 Hz), 128.20 (d, J ˆ
9.7 Hz), 127.72, 127.10 (d, J ˆ 1.0 Hz), 89.74 (d, J ˆ 5.6 Hz), 74.01 (d, J ˆ
1.4 Hz), 72.65 (d, J ˆ 1.3 Hz), 71.95, 70.36, 46.35 (d, J ˆ 26.6 Hz); 31P NMR
(CDCl3, 162 MHz): d ˆ 24.3; MS (EI, 70 eV): m/z (%): 804 (1), 802 (1), 594
(47), 410 (100), 369 (18), 186 (38), 108 (69); C48H46B2P2Ru (807.53): calcd C
71.39, H 5.74; found C 71.23, H 5.52.
‡
162 MHz): d ˆ 23.3; MS (EI, 70 eV): m/z (%): 808 (M , 63), 763 (32), 748
(42), 720 (32), 706 (88), 647 (15), 382 (47), 362 (14), 319 (21), 128 (100);
C50H62FeN2P2 (808.85): calcd C 74.25, H 7.72, N 3.46; found C 74.22, H 7.80,
N 3.36. Data for meso-30b (from racemic 17b): IR (KBr): nÄmax ˆ 3068 (w),
3050 (w), 2926 (s), 2854 (s), 2813 (m), 2771 (m), 1432 (s), 826 (m), 748 (s),
698 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.65 ± 7.60 (m, 4H), 7.40 ± 7.30 (m,
6H), 7.20 ± 7.05 (m, 10H), 4.38 (s, 2H), 3.85 (s, 2H), 3.72 ± 3.70 (m, 2H), 3.48
(s, 2H), 1.65 (s, 12H), 1.27 ± 1.05 (m, 16H), 0.98 ± 0.90 (m, 6H); 13C NMR
(CDCl3, 75 MHz): d ˆ 140.58 (d, J ˆ 7.1 Hz), 139.10 (d, J ˆ 9.2 Hz), 135.67
(d, J ˆ 22.7 Hz), 132.10 (d, J ˆ 18.5 Hz), 129.99, 128.09 (d, J ˆ 8.0 Hz),
127.30 (d, J ˆ 6.6 Hz), 127.05, 97.37 (d, J ˆ 24.4 Hz), 75.93 (d, J ˆ 9.3 Hz),
74.26 (d, J ˆ 5.4 Hz), 72.47, 70.43, 60.32 (d, J ˆ 8.0 Hz), 39.55, 32.12, 29.55,
27.95, 22.74, 14.16; 31P NMR (CDCl3, 162 MHz): d ˆ 23.6; MS (EI,
(R,R)-1,1'-Bis(a-thioacetophenylmethyl)ferrocene (29): The diacetate 12e
(56 mg, 0.12 mmol) was dissolved in acetic acid (3 mL) and KSAc (114 mg,
1.0 mmol) was added. The mixture was heated to 508C for 3 h. After
cooling to room temperature volatile matter was removed in vacuum and
the residue dissolved in water (10 mL) and ether (30 mL). The organic
layer was washed with water (10 mL) and dried. Concentration and
chromatography of the residue (hexanes/MTBE 10:1) gave the dithioace-
tate 29 (60 mg, 97%, dl:meso ˆ 90:10). Glassy yellow solid; [a]d ˆ 130
(c ˆ 1.35, CHCl3); IR (film): nÄmax ˆ 2970 (m), 2930 (m), 2830 (w), 1680 (vs),
‡
70 eV): m/z (%): 808 (M , 18), 762 (7), 746 (15), 718 (100), 533 (7), 382 (46),
359 (43), 319 (19), 128 (27); C50H62FeN2P2 (808.85): calcd C 74.25, H 7.72, N
3.46; found C 74.13, H 7.89, N 3.75. As by-product the monophosphorylated
diamine ((aR,a'R)-2,1'-bis(a-N,N-dimethylaminoethyl)-(S)-1-(diphenyl-
phosphino)ferrocene, 83 mg, 35%) was isolated; yellow oil; [a]d ˆ 120
(c ˆ 1.11, CHCl3); IR (film): nÄmax ˆ 3060 (w), 2920 (vs), 2860 (s), 2820 (w),
1
1455 (w), 1355 (m), 1110 (vs), 950 (s), 830 (s), 710 (s); H NMR (CDCl3,
300 MHz): d ˆ 7.31 ± 7.17 (m, 10H), 5.57 (s, 2H), 4.08 ± 4.07 (m, dl)/4.02 ±
4.01 (m, meso)/4.00 ± 3.98 (m)/3.95 ± 3.94 (m, meso)/3.86 ± 3.85 (m, dl, 8H
total), 2.27 (s, dl)/2.26 (s, meso, 6H total); 13C NMR (CDCl3, 75 MHz): d ˆ
193.93, 142.12, 128.29, 128.00, 127.25, 89.82, 69.43, 69.36, 69.21, 68.65, 47.76,
30.22 (dl); 128.03, 69.28, 68.89 (meso, separated signals); MS (EI, 70 eV): m/
1
2780 (m), 1435 (s), 1030 (m), 820 (m), 740 (s), 695 (s); H NMR (CDCl3,
300 MHz): d ˆ 7.65 ± 7.60 (m, 2H), 7.35 ± 7.33 (m, 3H), 7.19 ± 7.13 (m, 5H),
4.31 (s, 1H), 4.20 (t, J ˆ 2.3 Hz, 1H), 4.02 ± 4.01 (m, 1H), 3.98 ± 3.93 (m,
1H), 3.87 ± 3.86 (m, 1H), 3.85 ± 3.83 (m, 3H), 2.34 (dd, J ˆ 10.6, 3.3 Hz,
‡
z (%): 514 (M , 53), 440 (6), 396 (30), 364 (27), 285 (100), 208 (33), 154 (84),
43 (45); C28H26FeO2S2 (514.48): calcd C 65.37, H 5.09; found C 65.28, H 5.10.
1H), 1.80 (s, 6H), 1.77 (s, 6H), 1.82 ± 1.25 (m, 16H), 0.98 ± 0.91 (m, 6H); 13
C
NMR (CDCl3, 75 MHz): d ˆ 141.28 (d, J ˆ 7.4 Hz), 139.20 (d, J ˆ 9.6 Hz),
135.72 (d, J ˆ 22.35 Hz), 132.02 (d, J ˆ 18.6 Hz), 128.89, 128.06 (d, J ˆ
8.0 Hz), 127.22 (d, J ˆ 6.7 Hz), 126.91, 96.75 (d, J ˆ 23.7 Hz), 85.56, 76.29
(d, J ˆ 8.7 Hz), 72.55 (d, J ˆ 5.7 Hz), 71.70, 70.37, 70.07 (d, J ˆ 4.2 Hz),
68.99, 67.60, 61.82, 61.50 (d, J ˆ 6.4 Hz), 40.26, 39.43, 32.55, 32.21, 31.25,
28.77, 28.29, 27.01, 22.75, 22.71, 14.17, 14.14; 31P NMR (CDCl3, 162 MHz):
General procedure H for the aminophosphines 30 and 31: The diamine
(1.04 mmol) was dissolved in Et2O (5 mL) and BuLi (1.6m in hexanes,
3 mL, 4.1 mmol) was added within 10 min. After 10 ± 30 min the color
changed from yellow to red. After 6 h diphenylchlorophosphine (1.55 g,
7.0 mmol) was added at such a rate that the exothermic reaction did not
cause the solvent to boil. After the addition was complete the resulting
suspension was stirred for 4 h at room temperature and hydrolyzed by
addition of saturated aqueous NaHCO3 (10 mL). A precipitate formed at
this stage was dissolved by adding ether (20 mL) or a small amount of
CH2Cl2. After separation of the phases the aqueous layer was extracted
with ether (20 mL). The combined organic layers were dried and
concentrated, and the residue purified by column chromatography without
delay (otherwise rapid decomposition of the crude product was observed).
‡
d ˆ 22.7; MS (EI, 70 eV): m/z (%): 624 (M , 32), 579 (64), 564 (48), 536
(56), 522 (100), 465 (38), 350 (23), 178 (70), 128 (75); C38H53FeN2P (624.67):
calcd C 73.07, H 8.55, N 4.48; found C 72.83, H 8.60, N 4.58.
(aR,a'R)-2,2'-Bis(a-N,N-dimethylaminophenylmethyl)-(S,S)-1,1'-bis(di-
phenylphosphino)ferrocene (30c): Diamine 17c (216 mg, 0.48 mmol) was
lithiated (nBuLi, 1.8 mmol, 6 h) and treated with diphenylchlorophosphine
(900 mg, 4.1 mmol). Chromatography (hexanes/MTBE 2:1) afforded the
diastereomerically pure aminophosphine 30c (225 mg, 57%, >98% ee).
Yellow solid; m.p. 245 ± 2468C; HPLC (OD, 5% iPrOH, 1.0 mL/min,
254 nm): tR/min ˆ 5.08 (aRa'R,SS), 5.86 (aSa'S,RR); [a]d ˆ 331 (c ˆ 1.99,
(aR,a'R)-2,2'-Bis(a-N,N-dimethylaminoethyl)-(S,S)-1,1'-bis(diphenyl-
phosphino)ferrocene (30a): Diamine 17a (340 mg, 1.04 mmol) was lithi-
ated (nBuLi, 4.1 mmol, 6 h) and treated with diphenylchlorophosphine
Chem. Eur. J. 1998, 4, No. 5
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0965 $ 17.50+.25/0
965

P. Knochel, L. Schwink
FULL PAPER
CHCl3); IR (KBr): nÄmax ˆ 3090 (w), 3064 (w), 3030 (w), 2951 (m), 2856 (w),
2811 (m), 2764 (s), 1450 (s), 1006 (s), 814 (m), 737 (s), 703 (s); 1H NMR
(CDCl3, 300 MHz): d ˆ 7.35 ± 7.10 (m, 30H), 4.52 (s, 2H), 4.39 (s, 2H), 3.29
(s, 2H), 3.15 (s, 2H), 1.51 (s, 12H); 13C NMR (CDCl3, 75 MHz): d ˆ 139.99,
139.68 (d, J ˆ 6.8 Hz), 137.84 (d, J ˆ 10.1 Hz), 134.77 (d, J ˆ 23.0 Hz), 132.38
(d, J ˆ 13.4 Hz), 128.55, 128.49, 127.97 (d, J ˆ 8.0 Hz), 127.92, 127.44 (d, J ˆ
7.0 Hz), 127.30, 126.59, 98.09 (d, J ˆ 22.5 Hz), 76.51 (d, J ˆ 10.0 Hz), 73.13,
72.88 (d, J ˆ 5.2 Hz), 71.57, 68.27 (d, J ˆ 10.1 Hz), 42.00; 31P NMR (CDCl3,
coupling reaction without further purification. IR (KBr): nÄmax ˆ 3053 (w),
1
2944 (w), 2773 (w), 1436 (s), 1093 (m), 743 (s), 692 (s); H NMR (CDCl3,
300 MHz): d ˆ 8.40 ± 8.30 (m, 4H), 8.10 ± 8.04 (m, 4H), 7.80 ± 7.31 (m, 22H),
7.25 ± 7.21 (m, 2H), 7.10 ± 7.09 (m, 2H), 4.49 ± 4.48 (m, 2H), 4.24 ± 4.23 (m,
2H), 3.29 (s, 2H), 2.18 ± 2.17 (m, 2H), 1.60 (s, 12H); 13C NMR (CDCl3,
75 MHz): d ˆ 141.14, 137.29, 137.20, 137.10, 136.01, 135.94, 135.88, 132.76,
132.31, 131.85, 130.74, 129.33 (d, J ˆ 54.9 Hz), 128.43, 128.35, 128.27, 127.89,
127.74, 127.44, 127.35, 126.24, 126.18, 125.87, 125.74, 99.09, 78.52, 76.83 (d,
J ˆ 10.7 Hz), 72.43, 71.76 (d, J ˆ 26.9 Hz), 64.43, 43.17; 31P NMR (CDCl3,
162 MHz): d ˆ 39.3; MS (EI, 70 eV): m/z (%): 262 (40), 78 (20), 44 (100).
The palladium complexes 32a, 32b, and 33 were obtained from the
corresponding aminophosphines according to general procedure I and
were found to be mixtures of coordination isomers. They were used for the
asymmetric cross-coupling reactions without further purification.
‡
162 MHz): d ˆ 23.9; MS (EI, 70 eV): m/z (%): 820 (M , 11), 773 (40), 732
(12), 437 (100), 394 (33), 239 (19), 183 (29), 134 (38); C52H50FeN2P2
(820.78): calcd C 76.10, H 6.14, N 3.41; found C 76.22, H 6.35, N 3.42.
(aR,a'R)-2,2'-Bis(a-N,N-dimethylamino(2-naphtyl)methyl)-(S,S)-1,1'-bi-
s(diphenylphosphino)ferrocene (30d): Diamine 17d (193 mg, 0.35 mmol)
was lithiated (nBuLi, 1.23 mmol, 6 h) and treated with diphenylchloro-
phosphine (420 mg, 1.9 mmol). Chromatography (hexanes/MTBE 5:1 with
0.5% NEt3) afforded the diastereomerically pure aminophosphine 30d
(100 mg, 31%, >98% ee). Yellow solid; HPLC (OD, 2% iPrOH,
0.9 mLmin 1, 215 nm): tR/min ˆ 5.67 (aRa'R,SS), 7.01 (aSa'S,RR); [a]d ˆ
407 (c ˆ 0.79, CHCl3); IR (KBr): nÄmax ˆ 3054 (w), 2819 (w), 2775 (w), 1432
(m), 827 (m), 739 (m), 698 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.84 ± 7.80
(m, 2H), 7.70 ± 7.66 (m, 2H), 7.59 (s, 2H), 7.54 ± 7.48 (m, 4H), 7.35 ± 7.14 (m,
20H), 6.93 ± 6.87 (m, 4H), 4.72 ± 4.71 (m, 2H), 4.43 ± 4.42 (m, 2H), 3.37 ±
3.36 (m, 2H), 3.22 (s, 2H), 1.46 (s, 12H); 13C NMR (CDCl3, 75 MHz): d ˆ
139.82 (d, J ˆ 6.6 Hz), 137.94 (d, J ˆ 10.4 Hz), 134.77 (d, J ˆ 23.0 Hz),
133.02, 132.50 (d, J ˆ 19.8 Hz), 132.27, 128.55, 128.07 ± 127.24 (m), 126.41,
125.67, 125.24, 97.52 (d, J ˆ 22.1 Hz), 76.64 (d, J ˆ 4.5 Hz), 73.68 (d, J ˆ
3.5 Hz), 73.33 (d, J ˆ 5.7 Hz), 71.65 (d, J ˆ 4.1 Hz), 68.42 (d, J ˆ 9.1 Hz),
41.67; 31P NMR (CDCl3, 162 MHz): d ˆ 24.5; MS (EI, 70 eV): m/z (%):
General procedure J for asymmetric cross-coupling: The vinyl bromide
(2.5 mmol) and the Grignard reagent (5.0 mmol) were added to the
palladium complex (25 mmol) (and in some cases a zinc halide (10 mmol))
at 788C. The reaction mixture was warmed to 08C and stirred at this
temperature for 20 h. The resulting suspension was poured into 10%
hydrochloric acid (30 mL) and extracted with hexanes (3 Â 40 mL). The
combined organic layers were dried and concentrated, and the residue
distilled under reduced pressure. As an alternative a purification by column
chromatography was carried out.
(S)-3-Phenyl-1-butene (34a): Reaction of vinyl bromide (213 mg,
2.0 mmol) and 1-phenylethylmagnesium chloride (11.0 mL, 0.36m in
Et2O, 4.0 mmol) with palladium complex 31c (10 mg, 10 mmol) as catalyst
provided 34a (214 mg, 81%, 63% ee) after chromatography (hexanes). A
reaction with addition of ZnI2 (4 equiv) also gave 34a (86%, 82% ee).
Colorless liquid; GC (CB, 50 kPa, 808C): tR/min ˆ 11.78 (R), 11.92 (S);
[a]d ˆ ‡4.77 (c ˆ 16.16, CHCl3); IR (film): nÄmax ˆ 3055 (w), 3030 (w), 2960
(m), 2870 (w), 1640 (s), 1600 (s), 1495 (m), 1455 (m), 1370 (s), 910 (s), 755
(m), 700 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.32 ± 7.17 (m, 5H), 6.00
(ddd, J ˆ 17.0, 10.5, 6.5 Hz, 1H), 5.09 ± 4.98 (m, 2H), 3.50 (quin, J ˆ 6.7 Hz,
1H), 1.34 (d, J ˆ 7.0 Hz, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 145.55,
143.24, 128.39, 127.22, 126.10, 113.09, 43.17, 20.71; MS (EI, 70 eV): m/z (%):
‡
920 (M , 22), 874 (100), 831 (31), 487 (72), 444 (32), 184 (37); C60H54FeN2P2
(920.90): calcd C 78.26, H 5.91, N 3.04; found C 78.14, H 5.78, N 2.92.
(aR,a'R)-2,2'-Bis(a-N,N-dimethylaminophenylmethyl)-(S,S)-1,1'-bis(di-
phenylphosphino)ruthenocene (31): Diamine 18 (663 mg, 1.33 mmol) was
lithiated (nBuLi, 5.34 mmol, 6 h) and treated with diphenylchlorophosphine
(1.6 g, 7.3 mmol). Chromatography (hexanes/MTBE 3:1) afforded the dia-
stereomerically pure aminophosphine 31 (473 mg, 43%, >98% ee). Color-
less solid; HPLC (OD, 2% iPrOH, 0.9 mL/min, 215 nm): tR/min ˆ 5.93
(aRa'R,SS), 7.20 (aSa'S,RR); [a]d ˆ 183 (c ˆ 0.52, CHCl3); IR (KBr):
nÄmax ˆ 3053 (w), 2946 (w), 2771 (m), 1434 (m), 1015 (m), 741 (s), 698 (s); 1H
NMR (CDCl3, 300 MHz): d ˆ 7.27 ± 7.05 (m, 30H), 4.40 (s, 2H), 4.25 (d, J ˆ
5.6 Hz, 2H), 3.40 ± 3.36 (m, 4H), 1.67 (s, 12H); 13C NMR (CDCl3, 75 MHz):
d ˆ 144.63, 138.83 (d, J ˆ 38.7 Hz), 138.72 (d, J ˆ 39.5 Hz), 134.51 (d, J ˆ
22.6 Hz), 132.73 (d, J ˆ 18.9 Hz), 128.31 (d, J ˆ 5.9 Hz), 127.80, 127.72,
127.60 (d, J ˆ 5.0 Hz), 126.57, 103.81 (d, J ˆ 25.6 Hz), 82.20 (d, J ˆ 13.2 Hz),
76.26 (d, J ˆ 5.0 Hz), 75.61, 74.67, 68.21 (d, J ˆ 12.4 Hz), 43.78; 31P NMR
‡
132 (M , 25), 117 (100), 91 (48); C10H12 (132.21): calcd C 90.85, H 9.15;
found C 90.61, H 9.31.
(S)-(E)-1,3-Diphenyl-1-butene (34b): Reaction of b-bromostyrene
(458 mg, 2.5 mmol) and 1-phenylethylmagnesium chloride (13.9 mL,
0.36m in Et2O, 5.0 mmol) with palladium complex 31c (25 mg, 25 mmol)
as catalyst provided 34b (452 mg, 87%, 93% ee) after chromatography
(hexanes). A reaction with addition of ZnCl2 (4 equiv) also gave 34b (82%,
29% ee). Colorless liquid; b.p. 1208C (Kugelrohr, 0.7 mmHg); HPLC (OD,
0.25% iPrOH, 0.9 mLmin 1, 215 nm): tR/min ˆ 7.41 (S), 8.05 (R); [a]d ˆ
39.3 (c ˆ 2.51, CHCl3); 34.2 (c ˆ 2.60, benzene); IR (film): nÄmax ˆ 3030
(w), 2970 (w), 1600 (w), 1495 (m), 1450 (m), 1375 (w), 965 (s), 745 (s), 695
(s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.51 ± 7.30 (m, 10H), 6.61 ± 6.49 (m,
2H), 3.83 ± 3.74 (m, 1H), 1.62 (d, J ˆ 7.0 Hz, 3H); 13C NMR (CDCl3,
75 MHz): d ˆ 145.58, 137.56, 135.19, 128.55, 128.44, 127.26, 127.00, 126.18,
‡
(CDCl3, 162 MHz): d ˆ 24.2; MS (EI, 70 eV): m/z (%): 821 (M , 100), 806
(36), 778 (17), 746 (10), 593 (5), 517 (5), 134 (59); C48H50N2P2Ru (817.95):
calcd C 70.48, H 6.16, N 3.42; found C 70.71, H 6.13, N 3.21.
General procedure
I for the palladium complexes 32 and 33: The
aminophosphine (0.15 mmol) and PdCl2(MeCN)2 (40.1 mg, 0.15 mmol)
were suspended in toluene (4 mL) and stirred for 12 h at room temperature.
A slow change in color from yellow to deep red was observed. Removal of
the solvent in vacuum gave a quantitative yield of the palladium complex.
‡
126.13, 42.52, 21.19; MS (EI, 70 eV): m/z (%): 208 (M , 84), 193 (71), 178
(23), 130 (19), 115 (88), 105 (100), 91 (46); C16H16 (208.30): calcd C 92.26, H
7.74; found C 92.49, H 7.50.
(aR,a'R)-2,2'-Bis(a-N,N-dimethylaminophenylmethyl)-(S,S)-1,1'-bis(di-
phenylphosphino)ferrocenepalladium(ii) chloride (32c): From aminophos-
phine 30c (127 mg, 0.15 mmol) and PdCl2(MeCN)2 (40.1 mg, 0.15 mmol).
Red powder; m.p. 1768C (decomp.); [a]d ˆ 130 (c ˆ 0.69, CHCl3); IR
(KBr): nÄmax ˆ 3055 (w), 2950 (m), 2860 (w), 2818 (w), 2773 (w), 1436 (s),
1093 (m), 743 (s), 692 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 8.17 (s, 4H),
7.99 (s, 4H), 7.42 ± 7.32 (m, 12H), 7.20-7.14 (m, 6H), 6.81 (s, 4H), 4.34 (s,
2H), 4.11 (s, 2H), 3.04 (s, 2H), 2.32 (s, 2H), 1.52 (s, 12H); 13C NMR
(CDCl3, 75 MHz): d ˆ 143.51, 136.74 (t, J ˆ 6.7 Hz), 135.84 (t, J ˆ 4.6 Hz),
132.53 (d, J ˆ 57.1 Hz), 131.63, 130.62, 129.05 (d, J ˆ 55.2 Hz), 128.07, 127.44,
127.30, 127.02, 99.03, 77.99, 76.46 (d, J ˆ 17.4 Hz), 72.73 (d, J ˆ 55.5 Hz),
72.07, 64.07, 42.92; 31P NMR (CDCl3, 162 MHz): d ˆ 40.0; MS (EI, 70 eV):
m/z (%): 262 (43), 183 (22), 72 (33), 57 (65), 43 (100); C52H50Cl2FeN2P2Pd
(998.10): calcd C 62.58, H 5.05, N 2.81; found C 62.54, H 5.15, N 2.50.
(S)-(E)-4-Phenyl-2-pentene (34c): Reaction of (E)-1-bromo-1-propene
(107 mg, 0.88 mmol) and 1-phenylethylmagnesium chloride (5.5 mL, 0.36m
in Et2O, 2.0 mmol) with palladium complex 31c (5 mg, 5 mmol) as catalyst
provided 34c (88 mg, 68%, 65% ee) after chromatography (hexanes). (The
enantiomeric excess was determined by RuCl3/NaIO4 cleavage and
esterification of the resulting 2-phenylpropionic acid with (S)-methyl
mandelate;[33] the crude derivatization product was analyzed by NMR.)
Colorless liquid; [a]d ˆ ‡10.2 (c ˆ 0.98, CHCl3); IR (film): nÄmax ˆ 3030 (w),
2970 (s), 2880 (w), 1600 (w), 1495 (m), 1440 (s), 1375 (m), 1015 (m), 695 (s),
770 (s), 700 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.36 ± 7.31 (m, 2H), 7.27-
7.19 (m, 3H), 5.70 ± 5.62 (m, 1H), 5.54 ± 5.46 (m, 1H), 3.45 (quin, J ˆ 6.9 Hz,
1H), 1.73 ± 1.70 (m, 3H), 1.39 ± 1.36 (m, 3H); 13C NMR (CDCl3, 75 MHz):
d ˆ 146.47, 136.27, 128.32, 127.13, 125.90, 123.61, 42.35, 21.47, 17.87; MS (EI,
‡
70 eV): m/z (%): 146 (M , 44), 131 (100), 115 (27), 91 (62), 77 (28); C11H14
(146.23): calcd C 90.35, H 9.65; found C 90.16, H 9.52.
(aR,a'R)-2,2'-Bis(a-N,N-dimethylamino(2-naphthyl)methyl)-(S,S)-1,1'-b-
is(diphenylphosphino)ferrocenepalladium(II) chloride (32d): From ami-
nophosphine 30d (127 mg, 0.138 mmol) and PdCl2(MeCN)2 (35.7 mg,
0.138 mmol). The red powder obtained was used in the asymmetric cross-
(S)-(E)-7-Chloro-2-phenyl-3-heptene (34d): Reaction of (E)-1-bromo-5-
chloro-1-pentene (183 mg, 1.00 mmol) and 1-phenylethylmagnesium chlor-
ide (5.5 mL, 0.36m in Et2O, 2.0 mmol) with palladium complex 31c (10 mg,
966
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Chem. Eur. J. 1998, 4, No. 5

c2-Symmetrical Ferrocenyl Ligands
950±968
10 mmol) as catalyst provided 34d (135 mg, 65%, 11% ee) after chroma-
tography (hexanes/MTBE 50:1). (The enantiomeric excess was determined
by RuCl3/NaIO4 cleavage and esterification of the resulting 2-phenyl-
propionic acid with (S)-methyl mandelate;[33] the crude derivative was
analyzed by NMR.) Colorless liquid; [a]d ˆ ‡3.8 (c ˆ 1.25, CHCl3); IR
(film): nÄmax ˆ 3020 (w), 2950 (s), 1600 (m), 1480 (m), 1445 (s), 1370 (w), 960
(s), 905 (m), 700 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.38 ± 7.32 (m, 2H),
7.27 ± 7.21 (m, 3H), 5.72 (ddt, J ˆ 15.3, 6.7, 1.3 Hz, 1H), 5.47 (dtd, J ˆ 15.4,
6.7, 1.3 Hz, 1H), 3.56 (t, J ˆ 6.6 Hz, 2H), 3.48 (quin, J ˆ 6.9 Hz, 1H), 2.22 (q,
J ˆ 6.9 Hz, 2H), 1.88 (quin, J ˆ 6.8 Hz, 2H), 1.41 (d, J ˆ 7.0 Hz, 3H); 13C
NMR (CDCl3, 75 MHz): d ˆ 146.10, 136.60, 128.34, 127.08, 127.04, 125.97,
(1S,2S,3R)-1,3-Diphenyl-1,2-butanediol (35): AD-mix (Aldrich, 2.52 g) was
dissolved in water (9 mL) and tert-butanol (9 mL) and the solution cooled
to 08C. Methanesulfonic amide (174 mg) and the olefin 34b (378 mg,
1.82 mmol) were added. Rapid stirring was continued for 24 h at 08C. Solid
Na2SO5 (2.0 g) was added. After 30 min the reaction mixture was
partitioned between water (20 mL) saturated aqueous NH4Cl (20 mL)
and ether (40 mL). The aqueous phase was extracted with ether (2 Â
40 mL) and the combined organic layers dried and concentrated. The
residue was purified by column chromatography (hexanes/MTBE 3:1) to
provide the diol 35 (373 mg, 85%) containing 10% of the (1R,2R,3R)-
diastereomer. Colorless solid; m.p. 128 ± 1298C; [a]d ˆ ‡8.9 (c ˆ 0.73,
CHCl3); IR (film): nÄmax ˆ 3290 (s), 3029 (w), 2906 (w), 1494 (m), 1452 (m),
1121 (m), 1025 (s), 765 (m), 699 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.34 ±
7.20 (m, 10H), 4.53 (t, J ˆ 5.3 Hz, minor)/4.48 (t, J ˆ 4.6 Hz, major, 1H
total), 3.89 ± 3.84 (m, minor)/3.80 ± 3.75 (m, major, 1H total), 2.90 ± 2.81 (m,
1H), 2.66 ± 2.64 (m, 1H), 2.26 ± 2.20 (m, 1H), 1.35 (d, J ˆ 7.0 Hz, 3H); 13C
NMR (CDCl3, 75 MHz): d ˆ 144.55, 141.76, 128.44, 128.28, 127.58, 126.52,
126.35, 80.02, 73.77, 41.55, 15.96 (major); 142.94, 141.53, 128.53, 128.31,
127.74, 126.79, 126.24, 79.28, 74.42, 19.30 (minor, separated signals); MS
‡
44.30, 42.23, 32.24, 29.56, 21.45; MS (EI, 70 eV): m/z (%): 208 (M , 24), 193
(8), 131 (100), 117 (21), 105 (46), 91 (35); C13H17Cl (208.73): calcd C 74.81,
H 8.21; found C 74.82, H 8.37.
(S)-(E)-2,4-Diphenyl-2-pentene (34e): Reaction of (E)-1-bromo-2-phenyl-
1-propene (138 mg, 0.70 mmol) and 1-phenylethylmagnesium chloride
(4.0 mL, 0.36m in Et2O, 1.4 mmol) with palladium complex 31c (6 mg,
6 mmol) as catalyst provided 34e (81 mg, 52%, 59% ee) after distillation.
Colorless liquid; b.p. 1208C (Kugelrohr, 0.7 mmHg); HPLC (OD, 0.25%
‡
(EI, 70 eV): m/z (%): 242 (M , 2), 208 (3), 193 (4), 108 (100), 91 (24), 79
(27); C16H18O2 (242.32): calcd C 79.31, H 7.49; found C 79.36, H 7.74.
iPrOH, 0.9 mL/min, 215 nm): tR/min ˆ 6.80 (S), 7.34 (R); [a]D
ˆ
50.9 (c ˆ
1.48, CHCl3); IR (film): nÄmax ˆ 3030 (w), 2970 (m), 2870 (w), 1600 (m), 1495
(s), 1450 (s), 1380 (m), 1020 (m), 760 (s), 700 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 7.52 ± 7.30 (m, 10H), 6.04 (dd, J ˆ 9.3, 1.4 Hz, 1H), 3.97 (dq,
J ˆ 9.2, 7.0 Hz, 1H), 2.03 (d, J ˆ 1.4 Hz, 3H), 1.54 (d, J ˆ 6.9 Hz, 3H); 13C
NMR (CDCl3, 75 MHz): d ˆ 146.55, 143.77, 133.92, 133.42, 128.44, 128.13,
126.97, 126.67, 125.92, 125.78, 38.70, 22.39, 16.06; MS (EI, 70 eV): m/z (%):
(1S,2S,3R)-1,2-Epoxy-1,3-diphenylbutane (36): Under argon the diol 35
(347 mg, 1.43 mmol) was dissolved in CH2Cl2 (2 mL) and treated with trimethyl
orthoformate (0.23 mL) and trimethylsilyl chloride (0.24 mL). After 2 h the
volatiles were removed in vacuum and the residue was dissolved in MeOH
(10 mL). Addition of K2CO3 (300 mg) was followed by 6 h of rapid stirring.
The suspension was then poured into a mixture of saturated aqueous
NaHCO3 (40 mL) and water (40 mL) and extracted with ether (2 Â 80 mL).
The combined organic layers were dried, concentrated and the residue
purified by column chromatography (hexanes/MTBE 25:1) to provide the
epoxide 36 (250 mg, 78%) as a 90:10 mixture of diastereomers. Colorless
oil; [a]d ˆ 41.4 (c ˆ 3.67, CHCl3); IR (film): nÄmax ˆ 3030 (w), 2950 (m),
1605 (m), 1495 (m), 1460 (s), 885 (s), 760 (s), 695 (s); 1H NMR (CDCl3,
300 MHz): d ˆ 7.38 ± 7.24 (m, 10H), 3.75 (d, J ˆ 7.7 Hz, 1H), 3.15 ± 3.09 (m,
1H), 2.96 (quin, J ˆ 7.0 Hz, minor)/2.85 (quin, J ˆ 7.0 Hz, major, 1H total),
1.50 (d, J ˆ 7.0 Hz, major)/1.42 (d, J ˆ 7.2 Hz, minor, 3H total); 13C NMR
(CDCl3, 75 MHz): d ˆ 142.53, 137.46, 128.55, 128.35, 127.98, 127.28, 126.75,
125.51, 67.09, 58.22, 42.05, 17.49 (major); 142.60, 137.57, 128.51, 128.40,
127.45, 66.87, 57.46, 41.59, 17.12 (minor, separated signals); MS (EI, 70 eV):
‡
222 (M , 61), 207 (70), 129 (100), 105 (42), 91 (55), 77 (25); C17H18 (222.33):
calcd C 91.84, H 8.16; found C 91.62, H 8.03.
2-Methyl-3-phenyl-1-butene (34 f): Reaction of 2-bromopropene (200 mg,
1.65 mmol) and 1-phenylethylmagnesium chloride (7.5 mL, 0.36m in Et2O,
2.7 mmol) with palladium complex 31c (7.5 mg, 7.5 mmol) as catalyst provided
34 f (80 mg, 33%, racemic) after distillation. Colorless liquid; b.p. 708C
(Kugelrohr, 13 mbar); GC (CB, 50 kPa, 808C): tR/min ˆ 19.35, 19.54; IR
(film): nÄmax ˆ 3020 (w), 2960 (m), 1645 (w), 1450 (s), 1375 (w), 890 (m). 1H
NMR (CDCl3, 300 MHz): d ˆ 7.40 ± 7.24 (m, 5H), 4.97 (s, 1H), 4.93 (s, 1H),
3.46 (q, J ˆ 7.0 Hz, 1H), 1.68 (s, 3H), 1.45 (d, J ˆ 7.0 Hz, 3H); 13C NMR
(CDCl3, 75 MHz): d ˆ 149.16, 145.14, 128.25, 127.40, 126.04, 109.85, 46.54,
21.31, 20.00; C11H14 (146.23): calcd C 90.35, H 9.65; found C 90.50, H 9.66.
(R)-(E)-1-Phenyl-3-methyl-1-pentene (34g): Reaction of b-bromostyrene
(342 mg, 1.87 mmol) and sec-butylmagnesium chloride (4.8 mL, 0.83m in
Et2O, 4.0 mmol) with palladium complex 31c (5 mg, 5 mmol) as catalyst
provided 34g (260 mg, 75%, 15% ee) after distillation. (The enantiomeric
excess was determined by RuCl3/NaIO4 cleavage and esterification of the
resulting 2-methylbutyric acid with (S)-methyl mandelate;[33] the crude
‡
m/z (%): 224 (M , 7), 167 (41), 118 (100), 105 (39), 91 (30); C16H16O
(224.30): calcd C 85.68, H 7.19; found C 85.74, H 7.14.
(2R,4R)-2,4-Diphenyl-3-pentanol (37): Under argon copper(i) cyanide
(0.90 g, 10 mmol) was suspended in Et2O (25 mL) and cooled to 08C.
Within 15 min MeLi (1.61m in Et2O, 6.2 mL) was added dropwise. After
30 min at 08C the mixture was cooled to 788C. The epoxide 36 (179 mg,
0.80 mmol) in Et2O (2 mL) was added. After 5 min BF3 ´ OEt2 (0.17 mL)
was added dropwise over 5 min. The yellow suspension was stirred 30 min
at 788C and then brought to 08C for 2 h. Saturated aqueous NH4Cl
(40 mL) was added. Extraction with ether (3 Â 100 mL) was followed by
drying of the combined organic layers. The concentrated crude product was
purified by column chromatography (hexanes/MTBE 8:1) to provide the
diastereomerically pure alcohol 37 (130 mg, 68%, >98% ee). Colorless
solid; m.p. 80 ± 818C; HPLC (OD, 5% iPrOH, 0.9 mLmin 1, 215 nm): tR/
min ˆ 6.79 (SS), 7.32 (meso-s), 8.58 (RR), 10.35 (meso-r); [a]d ˆ 0.95 (c ˆ
1.68, CHCl3); IR (KBr): nÄmax ˆ 3569 (s), 3059 (w), 3027 (m), 2962 (s), 2932
(m), 2874 (m), 1601 (m), 1493 (s), 1452 (s), 1377 (m), 968 (s), 764 (s), 701
(vs); 1H NMR (CDCl3, 300 MHz): d ˆ 7.40 ± 7.26 (m, 10H), 3.86 (t, J ˆ
6.0 Hz, 1H), 2.90 (quin, J ˆ 7.0 Hz, dl)/2.81 (quin, J ˆ 6.7 Hz, meso-r, 2H
total), 1.64 ± 1.62 (m, meso-r)/1.40 ± 1.30 (m, 7H total); 13C NMR (CDCl3,
75 MHz): d ˆ 145.38, 143.40, 128.44, 128.38, 128.37, 127.87, 126.56, 126.28,
79.93, 42.87, 42.57, 19.03, 15.27 (dl); 145.19, 128.57, 127.52, 126.35, 80.65,
1
derivatization product was analyzed by H NMR (200 MHz, C6D6): major
diastereomer: d ˆ 6.18 (s); minor diastereomer: d ˆ 6.16 (s).) Colorless
liquid; [a]D
ˆ
3.5 (c ˆ 4.39, CHCl3); IR (film): nÄmax ˆ 3020 (w), 2950 (s),
2925 (s), 2870 (m), 1600 (w), 1490 (m), 1450 (s), 1375 (w), 960 (s), 740 (s),
690 (s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.38 ± 7.27 (m, 4H), 7.23 ± 7.16 (m,
1H), 6.35 (d, J ˆ 15.9 Hz, 1H), 6.10 (dd, J ˆ 15.9, 7.8 Hz, 1H), 2.21 (sept,
J ˆ 7.0 Hz, 1H), 1.42 (quin, J ˆ 7.0 Hz, 2H), 1.08 (d, J ˆ 6.8 Hz, 3H), 0.92 (t,
J ˆ 7.5 Hz, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 138.00, 136.65, 128.42,
128.22, 126.72, 125.97, 38.89, 29.82, 20.17, 11.79; MS (EI, 70 eV): m/z (%):
‡
160 (M , 24), 131 (100), 145 (8), 115 (15), 91 (48), 77 (6); C12H16 (160.26):
calcd C 89.94, H 10.06; found C 89.71, H 10.20.
(E)-8-Chloro-3-methyl-4-octene (34h): Reaction of (E)-1-bromo-5-chloro-
1-pentene (341 mg, 1.86 mmol) and sec-butylmagnesium chloride (4.8 mL,
0.83m in Et2O, 4.0 mmol) with palladium complex 31c (10 mg, 10 mmol) as
catalyst provided 34h (223 mg, 75%, racemic) after chromatography (hex-
anes). (The enantiomeric excess was determined by RuCl3/NaIO4 cleavage
and esterification of the resulting 2-methylbutyric acid with (S)-methyl
mandelate;[33] the crude derivative was analyzed by 1H NMR (200 MHz,
C6D6): major diastereomer: d ˆ 6.18 (s); minor diastereomer: d ˆ 6.16 (s).)
Colorless liquid; IR (film): nÄmax ˆ 2950 (s), 2930 (s), 2870 (m), 1450 (s), 1370
‡
42.32, 15.42 (meso-r); MS (EI, 70 eV): m/z (%): 240 (M , 3), 135 (23), 106
(100), 91 (55), 77 (20), 43 (41); C17H20O (240.35): calcd C 84.96, H 8.39;
found C 84.75, H 8.58. A small amount of meso-s 37 was isolated: colorless
oil; IR (film): nÄmax ˆ 3570 (s), 3060 (w), 3030 (w), 2960 (s), 2930 (m), 2875
(w), 1605 (w), 1495 (m), 1450 (s), 1385 (m), 1115 (m), 965 (m), 765 (s), 700
(s); 1H NMR (CDCl3, 300 MHz): d ˆ 7.35-7.27 (m, 10H), 3.87-3.81 (m, 1H),
1
(w), 960 (s); H NMR (CDCl3, 300 MHz): d ˆ 5.37 ± 5.24 (m, 2H), 3.54 (t,
J ˆ 6.7 Hz, 2H), 2.17 ± 2.10 (m, 2H), 1.97 (sept, J ˆ 6.8 Hz, 1H), 1.84 (quin,
J ˆ 7.3 Hz, 2H), 1.33 ± 1.22 (m, 2H), 0.95 (d, J ˆ 6.8 Hz, 3H), 0.83 (t, J ˆ
7.4 Hz, 3H); 13C NMR (CDCl3, 75 MHz): d ˆ 137.87, 126.36, 44.29, 38.39,
2.79 (quin, J ˆ 6.9 Hz, 2H), 1.39 (d, J ˆ 7.0 Hz, 6H), 1.36-1.34 (m, 1H); 13
H
‡
32.46, 29.76, 29.64, 20.32, 11.69; MS (EI, 70 eV): m/z (%): 162 (M , 4), 160
NMR (CDCl3, 75 MHz): d ˆ 143.38, 128.52, 128.34, 126.49, 79.86, 42.96,
‡
‡
(M , 14), 133 (11), 131 (34), 95 (21), 83 (54), 70 (36), 55 (100), 41 (47);
19.34; MS (EI, 70 eV): m/z (%): 240 (M , 3), 135 (32), 106 (100), 91 (48), 43
C9H17Cl (160.69): calcd C 67.27, H 10.66; found C 67.20, H 10.91.
(27); C17H20O (240.35): calcd C 84.96, H 8.39; found C 84.93, H 8.51.
Chem. Eur. J. 1998, 4, No. 5
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1998
0947-6539/98/0405-0967 $ 17.50+.25/0
967

P. Knochel, L. Schwink
FULL PAPER
Acknowledgments: This work was supported by the Deutsche Forschungs-
gemeinschaft (SFB 260, Graduierten Kolleg, Leibniz Program) and the
Fonds der Chemischen Industrie. We thank BASF (Ludwigshafen), Witco
E. Ruch, I. Ugi, Angew. Chem. 1970, 82, 77 ± 78; Angew. Chem. Int.
Ed. Engl. 1970, 9, 64 ± 65.
[18] a) A longer diastereoselective route to amine 15 was published
recently: H. C. L. Abbenhuis, U. Burckhardt, V. Gramlich, A. Togni,
A. Albinati, B. Müller, Organometallics 1994, 13, 4481 ± 4493; b) the
pentamethylcyclopentadienyl iron fragment is electron-rich and
therefore able to provide alone the stabilization of the a-cation which
in the C2-symmetrical cases is reached only with an aryl substituent.
[19] S. Allenmark, K. Kalen, A. Sandblom, Chem. Scr. 1975, 7, 97.
[20] For a discussion of older work on chiral ferrocenyl amines, see: a) R.
Herrmann, G. Hübener, F. Siglmüller, I. Ugi, Liebigs Ann. Chem.
1986, 251 ± 268; b) I. R. Butler, W. R. Cullen, Can. J. Chem. 1983, 61,
2354 ± 2358. For recent developments, see: c) D. Enders, R. Lochtman,
G. Raabe, Synlett 1996, 126 ± 128; d) D. Enders, R. Lochtman, ibid.
1997, 355 ± 356; e) T. Hayase, Y. Inoue, T. Shibata, K. Soai,
Tetrahedron Asymmetry 1996, 7, 2509 ± 2510; f) X. Verdaguer,
U. E. W. Lange, M. T. Reding, S. L. Buchwald, J. Am. Chem. Soc.
1996, 118, 6784 ± 6785.
[21] A. Togni, L. M. Venanzi, Angew. Chem. 1994, 106, 517 ± 547; Angew.
Chem. Int. Ed. Engl. 1994, 33, 497 ± 526.
[22] K. Püntener, L. Schwink, P. Knochel, Tetrahedron Lett. 1996, 37,
8165 ± 8168.
[23] a) A. Togni, G. Rihs, R. E. Blumer, Organometallics 1992, 11, 613 ±
621; b) A. Togni, R. Häusel, Synlett 1990, 633 ± 635; c) T. Hayashi, T.
Mise, M. Fukushima, M. Kagotani, N. Nagashima, Y. Hamada, A.
Matsumoto, S. Kawakami, M. Konishi, K. Yamamoto, M. Kumada,
Bull. Chem. Soc. Jpn 1980, 53, 1138 ± 1151.
[24] For a similar preparation of the diphosphines 27, see ref. [12b].
[25] D. Marquarding, H. Klusacek, G. Gokel, P. Hoffmann, I. Ugi, J. Am.
Chem. Soc. 1970, 92, 5389 ± 5393.
Â
(Bergkamen), Chemetall (Frankfurt), and SIPSY (Avrille, France) for
generous gifts of chemicals.
Received: September 8, 1997 [F816]
[1] a) M. Nogradi, Stereoselective Synthesis, VCH, Weinheim, 1995;
b) Houben ± Weyl, Methoden der Organischen Chemie, Stereoselec-
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Schaumann), Thieme, Stuttgart, 1995 ± 1996, Vol. E21d ± f; c) R.
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[2] a) H. H. Brintzinger, D. Fischer, R. Mülhaupt, B. Rieger, R. Way-
mouth, Angew. Chem. 1995, 107, 1255 ± 1283; Angew. Chem. Int. Ed.
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