Synthesis of ferrocenyl diphosphine ligands: Substitution of α-methoxy or α-dimethylamino groups by phosphines. Retention versus inversion: A stereochemical study

Organometallics 2010, 29, 6443–6458 6443

DOI: 10.1021/om100843u

Synthesis of Ferrocenyl Diphosphine Ligands: Substitution of r-Methoxy

or r-Dimethylamino Groups by Phosphines. Retention versus Inversion:

A Stereochemical Study

Raffael Schuecker and Walter Weissensteiner*

€

Institute of Organic Chemistry, University of Vienna, Wahringer Strasse 38, 1090 Vienna, Austria

Kurt Mereiter

Institute of Chemical Technologies and Analytics, Vienna University of Technology, Getreidemarkt 9/164SC,

A-1060 Vienna, Austria

Matthias Lotz and Felix Spindler

Solvias AG, Synthesis and Catalysis, P.O. Box, CH-4002 Basel, Switzerland

Received August 31, 2010

The stereochemical course of the exchange reaction of R-methoxy or R-dimethylamino groups by

phosphines in acetic acid has been studied for ferrocene derivatives that have either a ferrocenylethyl

or a benzylferrocenyl backbone. The reaction proceeded with either retention or inversion of

configuration depending on the substrate stereoisomer used. The parameters that influence the

stereochemical course of these reactions, such as relative configuration or substitution patterns, are

discussed.

Chart 1

Introduction

In a very recent paper Knochel, Lotz, and co-workers

reported on the synthesis and application of a novel type of

ferrocenyl diphosphine ligand (Chart 1, 1).¹In rhodium-

catalyzed asymmetric hydrogenations of two alkenes these

ligands performed excellently and gave products with quan-

titative conversion and with high enantiomeric excess (up to

96% ee). From a structural point of view, these ligands

differ significantly from typical ferrocenyl diphosphines

such as the Taniaphos- or Josiphos-type ligands²(Chart 1).

*To whom correspondence should be addressed. E-mail: walter.

weissensteiner@univie.ac.at.

(1) Lotz, M.; Schuecker, R.; Mereiter, K.; Knochel, P. Organo-

metallics 2010, doi om100830m.

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Grossheimann, G.; Knochel, P. Chem. Eur. J. 2002, 8, 843–852. (c) Lotz, M.;

Polborn, K.; Knochel, P. Angew. Chem., Int. Ed. 2002, 41, 4708–4711. (d)

Tappe, K.; Knochel, P. Tetrahedron: Asymmetry 2004, 15, 91–102.

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On complexation to a metal such as rhodium or palladium,

all of these ligands are expected to form chelate complexes.

However, unlike in the cases of Taniaphos³and Josiphos,⁴in

r

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6444 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

Scheme 1. Synthesis of Ligands 1 (top) and Proposed Key Steps for the Synthesis of Ligands 2 and 3 (bottom)

In the synthesis of ferrocene derivatives the exchange of

functional groups at the pseudo-benzylic R-position is con-

sidered to be a standard procedure that occurs with retention

of configuration in almost all cases.²Selected examples are

given in Scheme 2. In 1970 Ugi and co-workers⁵pointed out

that on treatment with methyl iodide and sodium methoxide

the dimethylamino group of both diastereomers (R,S_Fc)-9 and

(S,S_Fc)-9 can be substituted by a methoxy group with full

retention of configuration at the respective stereogenic center

(Scheme 2, reactions 1 and 2⁵). This type of reaction was

subsequently extended to a number of different leaving

groups such as acetate (reactions 4⁶and 5⁷), hydroxyl and

methoxy groups (reaction 6⁸), and different nucleophiles such

as amines, phosphines, sulfides, and carbon nucleophiles.⁹

These reactions have been used extensively,¹⁰particularly in

the synthesis of catalyst ligands, as exemplified by the synthe-

sis of Josiphos-type ligand (R,S_Fc)-13 (reactions 3^4aand 4⁶).

The vast majority of such substitution reactions proceed

with retention of configuration, and only in very few cases

has at least partial inversion of configuration been observed.¹¹

A particularly interesting example was recently reported by

Fukuzawa and co-workers.¹²The dimethylamino group of

(R,R_Fc)-18 was replaced by a methoxy group with clean

inversion of configuration at the stereogenic center to give

(S,R_Fc)-19 as the product (Scheme 3). This example is

particularly striking because substitution reactions on the

Figure 1. Molecular structure of [PdCl₂(R)-1a] (adopted from

ref 1).

complexes of ligands of type 1 the ferrocene unit does not

take part in the chelate ring but acts as a sterically demanding

substituent on that ring. Indeed, an X-ray diffraction study

of a palladium dichloride complex of ligand 1a, [PdCl₂(1a)],¹

showed that the ferrocene unit is attached to the chelate ring

in a pseudo-axial fashion with the Cp ring located in close

proximity to the palladium atom (Figure 1).

On the basis of these structural data we questioned whether

further ligand tuning could be achieved by substituting the

ferrocene Cp ring at either of its ortho positions (Chart 1,

derivatives 2 and 3; Figure 1) and how such derivatives could

be synthesized. The unsubstituted ligands of type 1 have been

reported to be accessible through a short reaction sequence.

Starting from enantiopure alcohol (R)-4, ligands (R)-1 were

obtained in a three-step sequence, 4 f 5 f 6 f 1 (Scheme 1,

top), in which all steps proceed with retention of configura-

tion at the stereogenic (benzylic) carbon. In principle, the

analogous ligands 2 and 3 should also be accessible in a

similar reaction sequence with the last step (the exchange of

the methoxy group by a phosphino group) being the key step

(Scheme 1, bottom). For example, provided that both dia-

stereomers (R,R_Fc)-7 and (R,S_Fc)-7 could be synthesized and

the configuration was retained, the exchange of the methoxy

by a phosphino group would lead to the final products

(R,R_Fc)-2 and (R,S_Fc)-2.

(5) Marquarding, D.; Klusacek, H.; Gokel, G.; Hoffmann, P.; Ugi, I.

J. Am. Chem. Soc. 1970, 92, 5389–5393.

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265. (c) Barbaro, P.; Bianchini, C.; Giambastiani, G.; Parisel, S. L. Coord.

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Long, N. J. Chem. Soc. Rev. 2004, 33, 313–328.

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stituted ferrocenediphosphines for asymmetric catalysis in ref , pp 205-235.

(11) (a) Taniguchi, N.; Uemura, M. Tetrahedron Lett. 1998, 39, 5385–

5388. (b) Burckhardt, U.; Drommi, D.; Togni, A. Inorg. Chim. Acta 1999,

296, 183–194. (c) Fukuzawa, S.; Wachi, D.; Suzuki, T.; Itoh, S. J. Org.

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Organometallics, Vol. 29, No. 23, 2010 6445

Scheme 2

Chart 2

In addition, in order to synthesize Josiphos-type ligands with

(R,R_Fc) or (S,S_Fc) instead of the usual (S,R_Fc) or (R,S_Fc)

configuration, the exchange of dimethylamino by phosphino

groups was also explored further.

Results

In order to investigate the stereochemical course of the

methoxy/phosphino exchange reaction, the diastereomeric

pairs of 7 and 20-22, all of which have a benzylferrocenyl

backbone, were synthesized in their racemic form and were

subjected to a reaction with diphenylphosphine in acetic

acid. In addition, (S,S_Fc)-8 and (R,R_Fc)-11 were prepared

in enantiomerically pure form and were reacted with dif-

ferent secondary phosphines in acetic acid as the solvent

(Chart 2). These reaction conditions were originally invented

for the diastereoselective and high-yielding synthesis of

Josiphos-type ligands^4a(Scheme 2, reaction 3).

Scheme 3

Synthesis of Derivatives 7, 8, 11, and 20-22. The amino

phosphine derivative (R,R_Fc)-11 was prepared according to

a literature procedure.⁶The racemic derivatives 20-22 of

relative (R,S_Fc) configuration were obtained according to a

synthesis route described for the corresponding enantiopure

derivatives with the (R,S_Fc) absolute configuration^8a(Scheme 4,

top). The synthesis of the diastereomers rac-(S,S_Fc)-20-22

started from bromoferrocene and is depicted in Scheme 4

(bottom). Reaction of bromoferrocene 24 with lithium

2,2,6,6-tetramethylpiperidide (LiTMP)¹³and benzaldehyde

structurally related substrates (R)-6¹(Scheme 1) and (R,R_Fc)-16⁸

(Scheme 2, reaction 6) both of which contain a benzylferro-

cenyl backbone gave products (R)-1 and (R,R_Fc)-17 with

clean retention of configuration. In view of these results, and

particularly since in the last step of the synthesis of ligands 2

and 3 the nucleophilic exchange of a methoxy for a phos-

phino unit is proposed, it seemed advantageous to study such

reactions in a more systematic way.

;

(13) (a) Steurer, M.; Tiedl, K.; Wang, Y.; Weissensteiner, W. Chem.

Commun. 2005, 4929–4931. (b) Steurer, M.; Wang, Y.; Mereiter, K.;

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Szewczyk, J. Inorg. Chem. Commun. 1999, 2, 576–580. (d) Mongin, F.;

Schlosser, M. Tetrahedron Lett. 1996, 37, 6551–6554.

In this contribution we report on the stereochemical course

of the exchange of R-methoxy by R-phosphino groups.

6446 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

Scheme 4

Scheme 5

gave both diastereomers of alcohol 25, with rac-(S,S_Fc)-25

being the major isomer (89% yield, 72% de). Methylation

with sodium hydride and methyl iodide resulted in rac-

(S,S_Fc)-20 (89%), and subsequent bromide/lithium exchange

and quenching with chlorodiphenylphosphine or chlorotri-

methylsilane gave rac-(S,S_Fc)-21 (78%) and rac-(S,S_Fc)-22

(95%), respectively. The configurational assignment of all

derivatives 20-22 is based on an X-ray diffraction study on

(R,S_Fc)-21^8aas well as on NMR data.

with NaH/MeI to give the intermediates rac-(R,R_Fc)-29

(66%) and rac-(S,R_Fc)-29 (69%). Further treatment with

butyllithium and chlorodiphenylphosphine gave the desired

products rac-(R,R_Fc)-7 (57%) and rac-(S,R_Fc)-7 (54%). In

this case, the configurational assignment was achieved by

carrying out an X-ray diffraction study on one diastereomer

of 7 (Figure 2), and this diastereomer was found to have the

(S,R_Fc) relative configuration. The diastereomer of 7 used in

this study was that obtained from 27 in the reaction sequence

27 f 29 f 7 and which itself was prepared diastereoselec-

tively by Richards’ protocol. It is worth mentioning that the

observed (S,R_Fc) relative configuration of 7 is identical to

that expected for 27, and this suggests that, as in the sequence

4 f 5 f 6 (Scheme 1), retention of configuration can be

assumed for the sequence 27 f 29 f 7.

The enantiomerically pure trimethylsilyl-substituted deriv-

ative (S,S_Fc)-8 was obtained in a three-step sequence from

2-(trimethylsilyl)ferrocenecarbaldehyde, (S_Fc)-30 (Scheme 6).

Once again, Richards’ protocol was followed, and aldehyde

(S_Fc)-30 was reacted with 2-bromophenylmagnesium chlo-

ride to give only one diastereomer of 31 (60% yield, after

recrystallization from heptane >99.8% ee). An X-ray dif-

fraction study on a racemic sample proved the expected

(S,S_Fc) relative configuration of 31 (Figure 2). Methylation

with NaH/MeI gave intermediate (S,S_Fc)-32, which was

finally transformed by treatment with ⁿBuLi and ClPPh₂

into the desired product (S,S_Fc)-8.

Both diastereomers of 7 are accessible in racemic form

from 2-ethylbromoferrocene,¹⁴rac-26 (Scheme 5). Bromide/

lithium exchange and subsequent reaction with 2-bromo-

benzaldehyde led to both diastereomers of 27 in a ratio of

about 1:1 and 79% overall yield. Furthermore, rac-(S,R_Fc)-27

could be synthesized diastereoselectively by applying a pro-

tocol originally developed by Richards and co-workers.⁷

Once again rac-26 was used as the starting material to obtain

2-ethylferrocenecarbaldehyde, rac-28, in 93% yield, and sub-

sequent treatment with 2-bromophenylmagnesium chlo-

ride¹⁵resulted in only one diastereomer for which based

;

on Richards’ protocol⁷the (S,R_Fc) relative configuration is

expected. After chromatographic separation the two diaste-

reomers, rac-(R,R_Fc)-27 and rac-(S,R_Fc)-27, were methylated

;

(14) Zirakzadeh, A.; Schuecker, R.; Weissensteiner, W. Tetrahedron:

Asymmetry 2010, 21, 1494–1502.

(15) Krasovskiy, A.; Knochel, P. Angew. Chem., Int. Ed. 2004, 43,

3333–3336.

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Organometallics, Vol. 29, No. 23, 2010 6447

Figure 2. Molecular structures of rac-(R,R_Fc)-2, rac-(S,R_Fc)-7, [PdCl₂((R,S_Fc)-3b)], rac-(S,S_Fc)-31, and rac-(S,S_Fc)-33 in the solid state.

Scheme 6

exchange reaction was somewhat slower, and two products were

formed. For example, reaction of rac-(S,S_Fc)-20 with diphenyl-

phosphine in acetic acid gave both diastereomers rac-(S,S_Fc)-33

and rac-(R,S_Fc)-33, with rac-(S,S_Fc)-33 being the major diaste-

reomer. In the case of the trihydridoboron complex of the rac-

(S,S_Fc)-configured diastereomer the molecular structure was

determined by X-ray diffraction (Figure 2). Furthermore, prod-

ucts 34 and 35 obtained as single diastereomers in the reaction

;

of rac-(R,S_Fc)-21 and rac-(R,S_Fc)-22 with HPPh₂/AcOH were

;

reacted with BH₃THF, and the NMR data of the resulting

3

trihydridoboron complexes rac-(R,S_Fc)-34(BH₃) and rac-

(R,S_Fc)-35(BH₃) were found to be identical to those reported

in the literature,¹⁶thus confirming the expected (R,S_Fc) relative

configuration.

Interestingly, although a wide variety of Josiphos-type

ligands have been prepared with full retention of config-

uration from (S,R_Fc)-11 [(S,R_Fc)-PPFA] or its enantiomer

(R,S_Fc)-11 (Scheme 2, reaction 3), the synthesis of their

diastereomeric analogues having (R,R_Fc) or (S,S_Fc) absolute

configuration has not yet been reported. For this purpose,

and also since [(R,R_Fc)-PPFA] is structurally related to the

R-methoxy-substituted derivative rac-(S,S_Fc)-21, (R,R_Fc)-11

was reacted in acetic acid with the secondary phosphines

diphenyl-, dicyclohexyl-, and di-tert-butylphosphine. All

three phosphines reacted to give full conversion, and the

majorproductineachcasewasthediastereomerwithretention

of configuration, i.e., (R,R_Fc)-36a-36c. However, unlike in the

case of rac-(S,S_Fc)-21 the reaction with diphenylphosphine and

the sterically more demanding dicyclohexylphosphine gave only

one diastereomer, while with di-tert-butylphosphine both dia-

stereomers were formed (de 84%).

Methoxy/Phosphino and Dimethylamino/Phosphino Exchange.

All methoxy dervatives 7, 8, and 20-22 as well as amino

derivative 11 were reacted in acetic acid with diphenylphos-

phine and in the cases of 8 and 11 also with other secondary

phosphines (for details see Scheme 7). The reaction mixtures

were analyzed, and the configurations of the products were

determined. The results are summarized in Table 1.

When the R-methoxy-substituted derivatives 20-22 were

reacted with HPPh₂in acetic acid, either one or two diastereo-

meric products were obtained depending on the diastereomer

used. The diastereomers of 20-22 with the (R,S_Fc) relative con-

figuration in each case gave only one product with clean retention

of configuration and with quantitative conversion. In the case of

derivatives 20-22 with the relative (S,S_Fc) configuration, the

(16) Ireland, T. Dissertation, Marburg, 1999.

6448 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

Scheme 7

Table 1. Methoxy/Phosphino and Amino/Phosphino Exchange Reactions^a

^aReaction conditions. Solvent: acetic acid; 11, 20, 21: 80 °C, 18 h; 7: 60 °C, 18 h; 8, 22: 60 °C, 24 h. ^bR⁰= Ph. ^cR⁰= 3,5-(CF₃)₂C₆H₃. ^dR⁰= Cy. ^eR⁰=

^tBu. ^fData taken from ref 1. ^gRef 4a. ^hIsolated yield.

In view of these results, we noticed with surprise that the

R-methoxy/phosphino exchange reaction of derivatives 7

and 8 with diphenylphosphine (7, 8) and bis(di-3,5-trifluoro-

methylphenyl)phosphine (8) in certain cases proceeded with

inversion of configuration. As reported recently, the at ferro-

cene unsubstituted derivative (R)-6 reacts with HPPh₂/

AcOH with clean retention of configuration¹to give (R)-1a

in 90% isolated yield and >99% de. Similarly, the at

ferrocene ethyl-substituted diastereomer rac-(R,R_Fc)-7 re-

acted in a similar way to its structurally related compounds,

but at phenyl unsubstituted analogues rac-(R,R_Fc)-20-22

and only one stereoisomer of 2 were formed with full con-

version. An X-ray diffraction study revealed the (R,R_Fc)

relative configuration (Figure 2), and this confirmed the

clean retention of configuration for this substitution reac-

tion. When the diastereomer rac-(S,R_Fc)-7 was reacted with

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Organometallics, Vol. 29, No. 23, 2010 6449

Scheme 8. Ugi’s Reaction Mechanism^a

^aAdopted from ref 5.

diphenylphosphine, two diastereomeric products were ob-

tained with full conversion, although the major diastereomer

rac-(R,R_Fc)-2 was identical to the product obtained from

rac-(R,R_Fc)-7. Therefore, the major diastereomer must be

formed with inversion of configuration. The trimethylsilyl-

substituted ferrocene (S,S_Fc)-8, which is structurally related

to rac-(S,R_Fc)-7, was also reacted with HPPh₂and with

[3,5-(CF₃)₂C₆H₃]₂PH in acetic acid. In both cases only one

diastereomer was formed, and this was obtained in low yield,

i.e., 3a (26%) and 3b (17%). The absolute configuration of

the product was determined by converting 3b into its di-

chloropalladium complex [PdCl₂(3b)] by treatment with

[PdCl₂(MeCN)₂]. An X-ray diffraction study gave the abso-

lute configuration of ligand 3b as (R,S_Fc), and this results

from inversion of configuration at the benzylic carbon.

the observation of Fukuzawa¹²that the trisubstituted

benzylferrocenyl-based derivative (R,R_Fc)-18 is transformed

into (S,R_Fc)-19 with inversion of configuration (Scheme 3).

Aminophosphines (R,R_Fc)-11 reacted in a similar way to

the R-methoxy-substituted derivatives rac-(S,S_Fc)-20-22 in

that reaction with diphenylphosphine and dicyclohexylphos-

phine gave a single product with clean retention of config-

uration [(R,R_Fc)-36a and 36b]. Only when the very bulky di-

tert-butylphosphine was used as the nucleophile was a small

amount of the diastereomer (S,R_Fc)-36c formed with inver-

sion of configuration along with the major product diaste-

reomer (R,R_Fc)-36c.

According to a mechanistic proposal put forward by Ugi

and co-workers,^5,17these types of exchange reactions are

expected to proceed through a two-step process with the

first step involving the participation of the ferrocene unit

(Scheme 8). Depending on the relative configuration (type A

or type B) and on the preferred conformation of the reactant,

in the first step the leaving group dissociates from the

R-carbon, and this leads to an intermediate carbocation or

a corresponding ion pair (Scheme 8, I or II). These inter-

mediates are thought to be stabilized by the participation of

the ferrocene unit. Provided that isomerization of I and II

does not take place and provided that the nucleophile

approaches the cationic intermediate on a trajectory coming

from above the Cp ring to the R-position, products with

overall retention of configuration are obtained. It has

already been pointed out by Ugi that the interconversion

of intermediates I and II may occur under conditions that

favor a long lifetime for these intermediates. In addition, one

might anticipate that in cases where interconversion of I

and II is feasible, for steric reasons cation I should be more

favored than II since in cation II close contacts of ste-

rically demanding substituents R¹and R⁰may lead to strong

repulsive interactions.

Discussion

In summary, for all of the derivatives investigated the

stereochemical course of the R-dimethylamino/phosphino

and R-methoxy/phosphino exchange reactions depended

primarily on the relative configuration of the substrates,

their substitution pattern, and, to a lesser extent, the nucleo-

phile used. All derivatives that had the relative configuration

of type A [Scheme 8, e.g., rac-(R,S_Fc)-20 or rac-(R,R_Fc)-7]

reacted with secondary phosphines in acetic acid with clean

retention of configuration.

In the reaction of substrates with a type B relative config-

uration [e.g., rac-(S,S_Fc)-20, rac-(S,R_Fc)-7, or (R,R_Fc)-11],

the stereochemical course of the substitution reaction was

strongly dependent on the substrate substitution pattern

of the ligand backbone. For example, all benzylferrocenyl-

based and disubstituted derivatives [(R)-6 and rac-(S,S_Fc)-

20-22)] reacted mainly with retention of configuration, but,

with the exception of (R)-6, a small amount of a second

isomer was also formed with inversion of configuration at the

benzylic R-position. Only for the trisubstituted derivatives

rac-(S,R_Fc)-7 and (S,S_Fc)-8 did the exchange reaction proceed

to either mainly rac-(R,R_Fc)-2, rac-(S,R_Fc)-7, [PdCl₂((R,S_Fc)-3b)],

with inversion of configuration. These latter results parallel

On the basis of this mechanistic proposal, the process

involving reactants of type A should be easiest, since in the

€

(17) Chen, C.; Frohlich, R.; Kehr, G.; Erker, G. Organometallics

2008, 27, 3248–3253.

6450 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

first step the more stable intermediate I is formed. Indeed, all

substrates of type A [rac-(R,R_Fc)-7, (S,R_Fc)-11, rac-(R,S_Fc)-

20-22] resulted in products with full conversion (and high

isolated yield) and with clean retention of configuration. In

this context it is worth mentioning that, according to the

reported molecular structures of (S,R_Fc)-11¹⁸and (R,S_Fc)-21^8a

in the solid state, these compounds adopt conformations in

which the orientation of the side chain already predefines

the structure of intermediate I with the NMe₂or OMe

group pointing straight above Cp and the side chain methyl

or phenyl group pointing away from the diphenylphos-

phino unit (for a schematic representation see Scheme 8,

first line).

Scheme 9

The exchange reaction with derivatives of type B, which

have either a side chain methyl group [(R,R_Fc)-11] or an

unsubstituted side chain phenyl group [rac-(S,S_Fc)-20-22]

(Scheme 8, R²= H), resulted in all but two cases [(R,R_Fc)-11/

HPPh₂, (R,R_Fc)-11/HPCy₂] in a mixture of two diastereo-

mers with the major isomer always being formed with

retention of configuration at the benzylic carbon. This

stereochemical course is consistent with a reaction pathway

of reactant (type B) f intermediate II f product (type B).

In the cases of the trisubstituted type B derivatives rac-

(S,R_Fc)-7 and (S,S_Fc)-8, which differ from substrates 20-22

by an additional substituent at the side chain phenyl ring,

the product distribution changes. Reaction of rac-(S,R_Fc)-7

again gives two product isomers with quantitative conver-

sion, but in this case the main product is formed with

inversion of configuration. The exchange reactions with

(S,S_Fc)-8 proceed exclusively with inversion of configuration

to give (R,S_Fc)-3a and (R,S_Fc)-3b as the final products.

According to Ugi’s proposal, the formation of the main

products would involve the reaction sequence reactant

(type B) f intermediate II f intermediate I f product

(type A). In these cases an isomerization process leading

from intermediate II mainly to I must be involved. Such a

process seems to be plausible, since for intermediate II one

would expect significant steric interactions between the ortho

substituent at ferrocene and the ortho substituent at the side

chain phenyl ring (Scheme 8, substituents R¹and R⁰).

However, considering the molecular structure of rac-

(S,R_Fc)-7 in the solid state we questioned whether an alter-

native pathway may lead directly from 7 to intermediate I. As

depicted in Figure 2 and shown schematically in Scheme 9,

derivative (S,R_Fc)-7 belongs to type B reactants but adopts a

conformation in which the methoxy group points below Cp

and toward the ethyl substituent, while the side chain phenyl

ring is turned away from the ferrocenyl ethyl group. In this

conformation the intermediate I is already preformed and

an acid-mediated dissociation of the leaving group would

directly lead to intermediate I.

this route. In this respect the trimethylsilyl-substituted di-

phosphines (R,S_Fc)-3a and (R,S_Fc)-3b have been prepared

in their enantiopure form. Further ligand synthesis and

catalytic testing is currently under investigation.

Summary

The exchange reaction of ferrocenyl R-methoxy or

R-dimethylamino substituents by secondary phosphines in

acetic acid has been studied on pairs of diastereomers that all

have either a ferrocenylethyl or benzylferrocenyl backbone.

The stereochemical course of such reactions was found to

depend strongly on the relative configuration of the starting

material and in the case of benzylferrocenyl-based deriv-

atives also on their substitution pattern. With PPFA-type

starting materials the reaction always proceeded with reten-

tion of configuration regardless of which PPFA diastereo-

mer was used. Only when (R,R_Fc)-PPFA was reacted with

the sterically very demanding di-tert-butylphosphine in

acetic acid was a small amount of the diastereomer formed

with inversion of configuration along with the main product.

The results obtained with benzylferrocenyl-based deriv-

atives were found to fall into three categories. Diastereomers

with a type A relative configuration [represented by, e.g.,

(R,S_Fc)-1-diphenylphosphino-2-[R-methoxyphenylmethyl]-

ferrocene, (R,S_Fc)-21] always gave the product with retention

of configuration regardless of the substitution pattern. In the

case of substrates with a type B relative configuration [e.g.,

(S,S_Fc)-21] the exclusively at ferrocene substituted deriv-

atives gave a mixture of diastereomers with the main product

formed with retention of configuration. With the trisubsti-

tuted ferrocenes of type B, all of which bear substituents at

ferrocene and at the side chain phenyl ortho position, prod-

ucts were formed mainly or exclusively with inversion of

configuration.

On the basis of the results of our stereochemical study we

conclude that the synthesis of catalyst ligands 2, 3, or related

derivatives can be carried out starting from precursors 7, 8,

or similar derivatives having either (R,R_Fc) or (R,S_Fc) rela-

tive configuration. However, since one diastereomeric pre-

cursor (of type A relative configuration) reacts with clean

retention and the second one mainly with inversion of con-

figuration (type B diastereomer), in both cases the prod-

uct of the same relative configuration is obtained. Therefore

only one stereoisomer is obtainable stereoselectively through

Experimental Part

General Considerations. NMR spectra were recorded on

Bruker DRX-400 and DRX-600 spectrometers in CDCl₃. Chem-

ical shifts (δ) are given relative to CHCl₃(¹H: 7.24 ppm), CDCl₃

(¹³C: 77.0 ppm), and 85% H₃PO₄(³¹P: 0 ppm). The coupling

constants in ¹³C{¹H} spectra are due to ¹³C-³¹P coupling. For

signal assignment the following terms were used: s, bs, d, dd, t, q,

and m refer to singlet, broad singlet, doublet, doublet of dou-

blets, triplet, quartet, and multiplet, respectively. The terms

(18) Einstein, F. W. B.; Willis, A. C. Acta Crystallogr. 1980, B36,

39–43.

Article

Organometallics, Vol. 29, No. 23, 2010 6451

method B) and could not be separated from the main product.

¹H NMR (400 MHz, CDCl₃): (selected signals) δ 0.47 (t, J =

7.4 Hz, 3H, CH₃), 0.89-1.00 (m, 1H, CH^AH^B), 1.24-1.36 (m,

1H, CH^AH^B), 3.52 (s, 5H, Cp⁰), 3.89 (m, 1H, CpH), 4.77 (m, 1H,

CpH), 6.25 (dd, J = 8.7 Hz, J = 6.1 Hz, 1H, H6). ³¹P NMR (162

MHz, CDCl₃): δ -18.6 (s), 5.8 (s).

rac-(R,R_Fc)-1-Ethyl-2-[r-diphenylphosphino-(2-diphenylphos-

phinophenyl)methyl]ferrocene, rac-(R,R_Fc)-2. Method A: A mix-

ture of rac-(R,R_Fc)-7 (290 mg, 0.5594 mmol) and diphenylphos-

phine (156 mg, 0.8391 mmol) in freshly distilled acetic acid

(4 mL) was degassed three times and stirred overnight at 60 °C

under argon. In order to determine the product distribution,

the solvent was removed under reduced pressure and the yellow

residue was dissolved in DCM (2 mL). An aliquot was analyzed

by NMR, and this revealed complete conversion and full

retention of configuration (331 mg, 0.4922 mmol, 88% yield).

Method B: A mixture of rac-(S,R_Fc)-7 (200 mg, 0.3858 mmol)

and diphenylphosphine (108 mg, 0.5787 mmol) in freshly dis-

tilled acetic acid (3 mL) was degassed three times and stirred

overnight at 60 °C under argon. In order to determine the

product distribution, the solvent was removed under reduced

pressure and the yellow residue was dissolved in DCM (2 mL).

An aliquot was analyzed by NMR, and this revealed complete

conversion and showed the diastereomeric ratio of rac-(R,R_Fc)-2

and rac-(S,R_Fc)-2 to be 2.6:1 (de = 72%). Mp: 185-188 °C

(dec). ¹H NMR (400 MHz, CDCl₃): δ 0.79 (t, J = 7.4 Hz, 3H,

CH₃), 1.73-1.86 (m, 1H, CH^AH^B), 2.09-2.22 (m, 1H,

CH^AH^B), 3.26 (s, 5H, Cp⁰), 3.71-3.77 (m, 1H, H5), 3.96-4.01

(m, 1H, H4), 4.52-4.59 (m, 1H, H3), 5.87 (dd, J = 10.9 Hz, J =

7.6 Hz, 1H, H6), 6.58-6.68 (m, 2H, Ph), 7.00-7.09 (m, 2H, Ph),

7.10-7.27 (m, 9H, H9 þ H10 þ Ph), 7.28-7.43 (m, 7H, Ph),

7.47-7.56 (m, 1H, H11), 7.57-7.64 (m, 2H, Ph), 8.11-8.20 (m,

1H, H12). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 13.2 (s, CH₃),

20.1 (d, J = 4.4 Hz, CH^AH^B), 39.0 (dd, J = 29.3 Hz, J = 14.4

Hz, C6), 64.2 (s, C5), 65.6 (s, C4), 67.6 (d, J = 15.4 Hz, C3), 68.6

(s, Cp⁰), 90.3 (d, J = 2.1 Hz, C1), 90.9 (d, J = 20.5 Hz, C2),

126.2 (s, C10), 127.5 (s, Ph-para), 127.7 (d, J = 7.3 Hz, Ph-

meta), 127.8-128.0 (m, 2 ꢀ Ph-meta), 128.2 (s, Ph-para), 128.6

(s, Ph-para), 128.7 (d, J = 5.2 Hz, Ph-meta), 129.2 (s, C11 þ

Ph-para), 130.9 (dd, J = 15.8 Hz, J = 4.8 Hz, C12), 132.7 (d,

J = 17.4 Hz, Ph-ortho), 134.1 (dd, J = 19.2 Hz, J = 3.6 Hz,

Ph-ortho), 134.4 (d, J = 19.4 Hz, Ph-ortho), 134.6 (dd, J =

10.0 Hz, J = 3.2 Hz, Ph-ipso), 134.9 (d, J = 21.5 Hz, Ph-ortho),

135.2 (s, C9), 136.1 (d, J = 12.0 Hz, Ph-ipso), 136.4 (d, J = 15.7

Hz, Ph-ipso), 136.9 (d, J = 18.9 Hz, C8), 139.1 (d, J = 10.5 Hz,

Ph-ipso), 151.4 (dd, J = 27.3 Hz, J = 12.5 Hz, C7). ³¹P NMR

(162 MHz, CDCl₃): δ -19.1 (s, C8-P), 17.2 (s, C6-P). HR-MS

(EI, 40 °C): m/z = [M]^þcalcd 672.1799 for C₄₃H₃₈FeP₂, found

672.1791.

(R,S_Fc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-(2-

diphenylphosphinophenyl)methyl]ferrocene Trihydridoboron, (R,S_Fc)-

3a(BH₃). Diphenylphosphine (1.59 g, 8.534 mmol) was added to

a solution of (S,S_Fc)-8 (3.20 g, 5.689 mmol) in freshly distilled

acetic acid (60 mL). The resulting mixture was degassed three

times and kept at 60 °C for 24 h. After cooling, the solvent was

removed under reduced pressure and the residue was redissolved

in a 1.0 M solution of borane in THF (56 mL, 56 mmol). After

stirring for 2 h at rt the reaction was quenched by dropwise

addition of water. The solvent was removed on a rotary evap-

orator, and the residue was extracted with EA (2 ꢀ 200 mL).

The combined organic layers were washed with water and brine

and dried over MgSO₄, and the solvents were removed under

reduced pressure. The crude product was subjected to chroma-

tography on aluminum oxide 90 using PE/EA = 30:1 f 20:1 as

eluent to give the title compound as a yellow solid (1.09 g, 1.492

mmol, 26% yield). Mp: 183 °C. ¹H NMR (400 MHz, CDCl₃): δ

-0.01 (s, 9H, Si(CH₃)₃), 0.61-1.64 (bs, 3H, P-BH₃), 3.40 (s, 5H,

Cp⁰), 4.01 (dd, J = 2.5 Hz, J = 1.0 Hz, 1H, H2), 4.48 (t, J =

2.5 Hz, 1H, H3), 4.93-4.95 (m, 1H, H4), 6.04 (dd, J = 15.1 Hz,

J = 10.2 Hz, 1H, H6), 6.64 (dd, J = 8.3 Hz, J = 7.0 Hz, 2H,

Figure 3. Atom-numbering scheme for NMR structure assign-

ments for 2, 3, 7, 8, 20-22, 25, 27-29, 31-35 (left) and 36

(right).

Ph^A-Dare used for phenyl or aryl groups of diphenylphosphino

or diarylphosphino units. In this respect, superscripts A-D are

used to distinguish between rings attached to different phos-

phorus atoms. A general atom-numbering scheme used for pro-

ton and carbon assignment is given in Figure 3. Melting points

were determined on a Kofler melting point apparatus and are

uncorrected. Mass spectra were recorded on Finnigan MAT 900

or MAT 95 spectrometers. Optical rotations were measured on

a Perkin-Elmer 241 polarimeter. HPLC was performed in an

isocratic mode on Agilent systems with Daicel Chiralcel OD-H

columns and mixtures of n-heptane and propan-2-ol. All reac-

tions required inert conditions and were carried out under an

argon atmosphere using standard Schlenk techniques. All sol-

vents were dried by standard procedures and distilled before

use.¹⁹Chromatographic separations were performed under

gravity on either aluminum oxide 90 (Merck) or silica (Merck,

40-63 μm). Abbreviations: DEE, diethyl ether; PE, petroleum

ether; DCM, dichloromethane; EA, ethyl acetate. LiTMP was

prepared according to a literature procedure.^13b

The following substances were prepared according to pub-

lished procedures: rac-23,²⁰rac-26,¹⁴(S_Fc)-30,²¹(R,R_Fc)-11.⁶

Compound 24 was purchased from Sigma.

General Procedure A. A mixture of methyl ether (0.5 mmol)

and diphenylphosphine (0.6 mmol) in acetic acid (2 mL) was

degassed three times and heated for an appropriate time. After

cooling, the solvent was removed under reduced pressure and

the remaining semisolid was redissolved in DCM (2 mL). An

aliquot was checked by NMR to determine the product dis-

tribution, and the solvent was again removed under reduced

pressure. The residue was treated with a 1.0 M solution of

borane in THF (5 mL) and stirred for a further 2 h. Water

was added dropwise to quench the reaction, and DEE was used

for extraction. The combined organic layers were washed with

water and brine and dried over MgSO₄, and the solvents were

removed on a rotary evaporator. The crude product was puri-

fied as described.

General Procedure B. A 60% dispersion of sodium hydride in

mineral oil (50 mmol) was placed in a Schlenk flask, and mineral

oil was removed by washing with PE (3 ꢀ 5 mL). The appro-

priate alcohol (33 mmol) dissolved in THF (15 mL) was added to

the flask containing the sodium hydride, and the mixture was

heated under reflux for 2.5 h. After cooling to 0 °C iodomethane

(50 mmol) was added dropwise and the resulting mixture was

stirred at rt for 3 h. The reaction was then quenched carefully

by the addition of methanol, THF was removed on a rotary

evaporator, and the residue was extracted with DEE (2 ꢀ 100

mL). The combined organic layers were washed with water and

brine and dried over MgSO₄, and the solvent was removed under

reduced pressure. The crude product was purified as described.

rac-(S,R_Fc)-1-Ethyl-2-[r-diphenylphosphino-(2-diphenylphos-

phinophenyl)methyl]ferrocene, rac-(S,R_Fc)-2. This compound

was obtained as a byproduct (see preparation of rac-(R,R_Fc)-2

(19) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory

Chemicals; Pergamon Press: Oxford, 1993.

(20) Mashburn, T. A.; Hauser, C. R. J. Org. Chem. 1961, 26, 1671–

1672.

(21) Riant, O.; Samuel, O.; Flessner, T.; Taudien, S.; Kagan, H. B.

J. Org. Chem. 1997, 62, 6733–6745.

6452 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

Ph^A-ortho), 7.12 (dd, J = 8.3 Hz, J = 7.0 Hz, 2H, Ph^A-meta),

7.15-7.23 (m, 7H, Ph^C-ortho þ Ph^D-meta þ Ph^C-meta þ

Ph^A-para), 7.24-7.28 (m, 3H, H9 þ H10 þ Ph^D-para),

7.28-7.31 (m, 1H, Ph^C-para), 7.32-7.36 (m, 3H, Ph^B-meta þ

Ph^B-para), 7.43-7.56 (m, 3H, H11 þ Ph^B-ortho), 7.82 (dd, J =

11.3 Hz, J = 9.6 Hz, 2H, Ph^D-ortho), 8.09-8.16 (m, 1H, H12).

¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 1.7 (d, J = 4.6 Hz,

Si(CH₃)₃), 41.3 (dd, J = 23.9 Hz, J = 25.3 Hz, C6), 68.7 (s, Cp⁰),

71.3 (s, C3), 72.7 (d, J = 2.5 Hz, C4), 73.7 (s, C2), 74.7 (d, J =

1.6 Hz, C1), 92.1 (d, J = 2.8 Hz, C5), 126.2 (d, J = 51.6,

Ph^C/D-ipso), 127.3 (d, J = 2.3 Hz, Ph^A-para), 127.5 (s, C10),

127.8, 127.9, 128.3 (3d, J = 15.5 Hz, J = 11.3 Hz, J = 10.0 Hz,

Ph^A-meta þ Ph^C-meta þ Ph^D-meta), 128.6 (d, J = 7.5 Hz,

Ph^B-meta), 128.7 (s, C11), 129.0 (s, Ph^B/C-para), 128.9 (d, J =

51.3 Hz, Ph^C/D-ipso), 130.5 (d, J = 2.4 Hz, Ph^B/C-para), 131.3

(d, J = 2.3 Hz, Ph^D-para), 132.5 (d, J = 16.6 Hz, Ph^A-ortho),

132.6 (s, C12), 134.1 (d, J = 8.5 Hz, Ph^C-ortho), 134.3 (d, J =

20.0 Hz, Ph^B-ortho), 134.8 (dd, J = 8.5 Hz, J = 3.9 Hz,

Ph^D-ortho þ C8), 136.5 (d, J = 12.3 Hz, Ph^B-ipso), 136.8 (s,

C9), 139.0 (d, J = 9.9 Hz, Ph^A-ipso), 147.0 (dd, J = 29.9 Hz, J =

3.1 Hz, C7). ³¹P NMR (162 MHz, CDCl₃): δ -19.2 (s, C8-P),

30.6 (bs, C6-P). Ph^Aþ Ph^Bconnected to C8-P, Ph^Cþ Ph^D

connected to C6-P. HR-MS (ESI-MS, MeOH/MeCN): m/z =

with saturated sodium bicarbonate, water, and brine and dried

over MgSO₄. The solvents were removed on a rotary evapora-

tor, and the crude product was purified by chromatography on

aluminum oxide 90 using PE/EA = 80:1 as eluent to give the

pure product as a yellow solid (969 mg, 0.9801 mmol, 17%

yield). Mp: 65 °C. ¹H NMR (400 MHz, CDCl₃): δ 0.28 (s, 9H,

Si(CH₃)₃), 3.87 (s, 5H, Cp⁰), 4.11-4.14 (m, 1H, H4), 4.25-4.28

(m, 1H, H2), 4.48 (t, J = 2.4 Hz, 1H, H3), 6.14 (dd, J = 11.7 Hz,

J = 4.8 Hz, 1H, H6), 6.93 (m, 2H, Ph^B-ortho), 7.07 (d, J =

6.2 Hz, 2H, Ph^D-ortho), 7.12 (m, 2H, Ph^B-meta), 7.18-7.24 (m,

3H, Ph^A-ortho þ Ph^B-para), 7.26-7.30 (m, 3H, Ph^A-meta þ

Ph^A-para), 7.31-7.44 (m, 6H, C9, C10, C11, C12 þ Ph^C-ortho),

7.69 (s, 1H, Ph^D-para), 7.72 (s, 1H, Ph^C-para). ¹³C{¹H} NMR

(100.6 MHz, CDCl₃): δ 1.2 (s, Si(CH₃)₃), 43.5 (dd, J = 27.1 Hz,

J = 29.0 Hz, C6), 69.0 (s, Cp⁰), 71.0 (d, J = 1.7 Hz, C4), 71.4 (s,

C3), 72.9 (d, J = 2.4 Hz, C1), 75.0 (s, C2), 93.2 (d, J = 10.3 Hz,

C5), 122.9 (q, J = 273.3 Hz, CF₃), 123.0 (q, J = 273.6 Hz, CF₃),

123.1-123.5 (m, Ph^C-para þ Ph^D-para), 127.5 (s, C10/C11),

128.3, 128.7, 128.8 (3s, C10/C11 þ Ph^A-para þ Ph^B-para), 128.3

(d, J = 7.2 Hz, Ph^B-meta), 128.5 (d, J = 6.0 Hz, Ph^A-meta),

130.2 (dd, J = 7.0 Hz, J = 5.0 Hz, C12), 131.0 (dd, J = 26.0 Hz,

J = 7.9 Hz, C-CF₃), 131.1 (dd, J = 26.8 Hz, J = 6.9 Hz, C-CF₃),

133.1 (d, J = 17.9 Hz, Ph^A-ortho), 133.5 (d, J = 20.3 Hz,

Ph^B-ortho), 134.4-134.9 (m, Ph^C-ortho þ Ph^D-ortho), 135.6 (d,

J = 13.5 Hz, C8), 136.3 (d, J = 10.0 Hz, Ph-ipso), 136.6 (s, C9),

136.9 (d, J = 16.9 Hz, Ph-ipso), 137.1 (d, J = 17.9 Hz, Ph-ipso),

[M]^þcalcd 730.2217 for C₄₄H₄₅BFeP₂Si, found 730.2224. [R]²⁰

λ

(nm): -53.3 (589), -57.6 (578), -82.1 (546) (c 0.988, CH₂Cl₂).

(R,S_Fc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-(2-

diphenylphosphinophenyl)methyl]ferrocene, (R,S_Fc)-3a. A solu-

tion of (R,S_Fc)-(3a(BH₃)) (856 mg, 1.172 mmol) in diethylamine

(100 mL) was stirred at rt overnight. The solvent was removed

using a rotary evaporator, and the residue was chromato-

graphed under inert conditions on aluminum oxide 90 using

PE/EA = 40:1 as eluent to give the title compound as a yellow

solid (626 mg, 0.8735 mmol, 75% yield). Mp: 75 °C. ¹H NMR

(400 MHz, CDCl₃): δ 0.14 (s, 9H, Si(CH₃)₃), 3.57 (s, 5H, Cp⁰),

4.05-4.08 (m, 1H, H2), 4.39 (t, J = 1.2 Hz, 1H, H3), 4.46-4.49

(m, 1H, H4), 5.82 (dd, J = 9.8 Hz, J = 2.4 Hz, 1H, H6),

6.76-6.84 (m, 4H, Ph^D-ortho þ Ph^B-ortho), 7.00-7.07 (m,

4H, Ph^D-meta þ Ph^C-meta), 7.12-7.18 (m, 4H, Ph^B-meta þ

Ph^D-para þ Ph^C-para), 7.19-7.23 (m, 2H, H10 þ Ph^B-para),

7.24-7.29 (m, 3H, H9 þ Ph^C-ortho), 7.30-7.35 (m, 3H,

Ph^A-meta þ Ph^A-para), 7.37-7.46 (m, 3H, H11 þ Ph^A-ortho),

7.83-7.90 (m, 1H, H12). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ

1.6 (s, Si(CH₃)₃), 42.4 (dd, J = 23.0 Hz, J = 25.5 Hz, C6), 68.5

(s, Cp⁰), 70.4 (s, C3), 71.1 (d, J = 7.3 Hz, C4), 73.5 (s, C1), 73.5

(s, C2), 96.2 (d, J = 14.5 Hz, C5), 126.2 (s, C10), 127.5 (d, J =

6.5 Hz, Ph^C/D-meta), 127.7 (s, Ph^B-para), 127.9, 128.0 (2d, J =

8.1 Hz, J = 7.0 Hz, Ph^C/D-meta þ Ph^B-meta), 128.4, 128.4,

128.5, 128.5 (4s, C11 þ Ph^D-para þ Ph^C-para þ Ph^A-para), 128.8

(d, J = 6.4 Hz, Ph^A-meta), 130.8 (dd, J = 13.7 Hz, J = 5.5 Hz,

C12), 133.1 (d, J = 18.7 Hz, Ph^B-ortho), 133.9 (d, J = 19.6 Hz,

Ph^A-ortho), 134.6 (d, J = 19.8 Hz, Ph^D-ortho), 134.9 (d, J = 19.3

Hz, C8), 135.0 (dd, J = 21.0 Hz, J = 2.5 Hz, Ph^C-ortho), 136.0

(d, J = 21.9 Hz, Ph-ipso), 136.3 (s, C9), 137.4 (d, J = 13.1 Hz,

Ph-ipso), 137.5 (d, J = 13.1 Hz, Ph-ipso), 139.0 (d, J = 11.0 Hz,

Ph-ipso), 150.4 (dd, J = 28.0 Hz, J = 9.9 Hz, C7). ³¹P NMR

(162 MHz, CDCl₃): δ -19.7 (d, J = 5.1 Hz, C8-P), 21.1 (d, J =

5.1 Hz, C6-P). Ph^Aþ Ph^Bconnected to C8-P, Ph^Cþ Ph^D

connected to C6-P. HR-MS (ESI-MS, MeOH/MeCN): m/z =

[M þ H þ 2O]^þcalcd 749.1858 for C₄₄H₄₃FeO₂P₂Si, found

137.5 (d, J = 11.0 Hz, Ph-ipso), 146.5 (d, J = 31.2 Hz, C7). ³¹

P

NMR (162 MHz, CDCl₃): δ -20.1 (d, J = 12.9 Hz, C8-P), 13.7

(d, J = 12.9 Hz, C6-P). Ph^Aþ Ph^Bconnected to C8-P, Ph^C

þ

Ph^Dconnected to C6-P. HR-MS (ESI-MS, MeOH/MeCN):

m/z = [M]^þcalcd 988.1377 for C₄₈H₃₈F₁₂FeP₂Si, found

988.1359. [R]²⁰(nm): þ109.1 (589), þ119.4 (578), þ175.3

λ

(546) (c 0.955, CH₂Cl₂).

rac-(S,R_Fc)-1-Ethyl-2-[r-methoxy(diphenylphosphinophenyl)-

methyl]ferrocene, rac-(S,R_Fc)-7. A 1.6 M solution of n-BuLi in

hexane (2.11 mL, 3.383 mmol) was added dropwise to a stirred

solution of rac-(S,R_Fc)-29 (1.331 g, 3.222 mmol) in THF (15 mL)

at -78 °C, and the mixture was stirred for 30 min. Chlorodi-

phenylphosphine (924 mg, 4.189 mmol) was added dropwise at

-78 °C, and stirring was continued for a further 30 min. After

warming to rt the mixture was stirred for a further 1 h followed

by quenching by the dropwise addition of water. The product

was extracted with EA (2 ꢀ 50 mL), and the combined organic

layers were washed with water and brine and dried over MgSO₄.

The solvents were removed under reduced pressure, and the

residue was subjected to chromatography on aluminum oxide 90

using PE/EA = 30:1 as eluent to give the product as a yellow

foam (0.903 g, 1.742 mmol, 54% yield). Mp: 134 °C. ¹H NMR

(400 MHz, CDCl₃): δ 0.88 (t, J = 7.5 Hz, 3H, CH₃), 1.98-2.11

(m, 1H, CH^AH^B), 2.27-2.40 (m, 1H, CH^AH^B), 3.22 (s, 3H,

OCH₃), 3.90-3.95 (m, 1H, H4), 3.97-4.02 (m, 1H, H5),

4.05-4.09 (m, 1H, H3), 4.15 (s, 5H, Cp⁰), 6.11 (d, J = 8.0 Hz,

1H, H6), 6.98-7.04 (m, 1H, H9), 7.13-7.19 (m, 1H, H10),

7.31-7.36 (m, 11H, H11 þ 2 ꢀ Ph-ortho þ 2 ꢀ Ph-meta þ 2 ꢀ

Ph-para), 7.37-7.42 (m, 1H, H12). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): δ 13.9 (s, CH₃), 21.1 (d, J = 3.8 Hz, CH^AH^B), 57.2 (s,

OCH₃), 64.8 (s, C4), 67.1 (s, C5), 67.4 (s, C3), 69.2 (s, Cp⁰), 77.7

(d, J = 26.4 Hz, C6), 88.1 (s, C1), 89.3 (s, C2), 127.5 (s, C10),

127.9 (d, J = 5.4 Hz, C12), 128.3-128.6 (m, 2 ꢀ Ph-meta þ 2 ꢀ

Ph-para), 129.4 (s, C11), 133.7 (d, J = 8.9 Hz, Ph-ortho), 133.8

(s, C9), 133.9 (d, J = 9.1 Hz, Ph-ortho), 135.5 (d, J = 14.3 Hz,

C8), 136.8 (d, J = 10.7 Hz, Ph-ipso), 137.1 (d, J = 10.4 Hz,

Ph-ipso), 147.1 (d, J = 24.0 Hz, C7). ³¹P NMR (162 MHz,

CDCl₃): δ -17.1 (s). HR-MS (EI, 30 °C): m/z = [M]^þcalcd

518.1462 for C₃₂H₃₁FeOP, found 518.1452.

749.1863. [R]²⁰(nm): -25.4 (589), -26.4 (578), -29.5 (546)

λ

(c 1.071, CH₂Cl₂).

(R,S_Fc)-1-Trimethylsilyl-2-[r-bis(3,5-bistrifluoromethylphenyl)-

phosphino-(2-diphenylphosphinophenyl)methyl]ferrocene, (R,S_Fc)-

3b. To a solution of (S,S_Fc)-8 (3.20 g, 5.689 mmol) in freshly

distilled acetic acid (60 mL) was added bis[3,5-bis(trifluoro-

methyl)phenyl]phosphine (3.91 g, 8.535 mmol), and the result-

ing mixture was degassed three times. After heating at 60 °C for

24 h the reaction was cooled to rt and the solvent was removed

under reduced pressure. The residue was extracted with DEE

(2 ꢀ 100 mL), and the combined organic layers were washed

rac-(R,R_Fc)-1-Ethyl-2-[r-methoxy(diphenylphosphinophenyl)-

methyl]ferrocene, rac-(R,R_Fc)-7. A 1.6 M solution of n-BuLi in

hexane (1.97 mL, 3.146 mmol) was added to a solution of rac-

(R,R_Fc)-29 (1.238 g, 2.997 mmol) in THF (15 mL) at -78 °C, and

the mixture was stirred for 30 min. Chlorodiphenylphosphine

Article

Organometallics, Vol. 29, No. 23, 2010 6453

(860 mg, 3.896 mmol) was added dropwise at -78 °C, and

stirring was continued for a further 30 min. After warming to

rt the mixture was stirred for 1 h followed by quenching by

dropwise addition of water. The product was extracted with EA

(2 ꢀ 50 mL), and the combined organics were washed with water

and brine and dried over MgSO₄. The solvents were removed

under reduced pressure, and the residue was subjected to chro-

matography on aluminum oxide 90 using PE/EA = 30:1 as

eluent to give the product as an orange-yellow, viscous oil

(0.890 g, 1.717 mmol, 57% yield). ¹H NMR (400 MHz, CDCl₃):

δ 1.22 (t, J = 7.5 Hz, 3H, CH₃), 2.53-2.68 (m, 2H, CH^AH^B),

2.71 (s, 3H, OCH₃), 3.92 (s, 5H, Cp⁰), 4.01-4.03 (m, 1H, H4),

4.06-4.09 (m, 1H, H3), 4.11-4.14(m, 1H, H5), 5.93(d, J=6.6Hz,

1H, H6), 7.03-7.07 (m, 1H, H9), 7.31-7.26 (m, 1H, H10),

7.32-7.43 (m, 10H, 2 ꢀ Ph-ortho þ 2 ꢀ Ph-meta þ 2 ꢀ Ph-para),

7.42-7.46 (m, 1H, H11), 7.66-7.72 (m, 1H, H12). ¹³C{¹H}

NMR (100.6 MHz, CDCl₃): δ 14.6 (s, CH₃), 21.1 (d, J = 3.7 Hz,

CH^AH^B), 56.3 (s, OCH₃), 66.2 (s, C4), 66.8 (d, J = 1.5 Hz, C3),

67.5 (s, C5), 69.3 (s, Cp⁰), 77.9 (d, J = 24.4 Hz, C6), 87.4 (s, C2),

90.0 (s, C1), 127.7 (s, C10), 127.9 (d, J = 5.1 Hz, C12),

128.4-128.7 (m, C11 þ 2 ꢀ Ph-para þ Ph-meta), 129.0 (d,

J = 14.5 Hz, Ph-meta), 133.4 (s, C9), 134.0 (d, J = 19.3 Hz,

Ph-ortho), 134.4 (d, J = 20.4 Hz, Ph-ortho), 135.8 (d, J = 15.1 Hz,

C8), 136.5 (d, J = 12.1 Hz, Ph-ipso), 137.0 (d, J = 10.4 Hz,

Ph-ipso), 146.6 (d, J = 22.3 Hz, C7). ³¹P NMR (162 MHz,

CDCl₃): δ -14.4 (s). HR-MS (EI, 30 °C): m/z = [M]^þcalcd

518.1462 for C₃₂H₃₁FeOP, found 518.1447.

(S,S_Fc)-1-Trimethylsilyl-2-[r-methoxy(diphenylphosphinophenyl)-

methyl]ferrocene, (S,S_Fc)-8. A solution of (S,S_Fc)-32 (8.55 g,

18.70 mmol) in THF (100 mL) was cooled to -78 °C, and a

1.6 M solution of n-BuLi in hexane (12.85 mL, 20.56 mmol) was

added dropwise. Stirring was continued for 30 min followed by

the dropwise addition of chlorodiphenylphosphine (5.36 g,

24.30 mmol). The mixture was stirred for a further 30 min at

-78 °C and for 1 h at rt. The reaction was then quenched by the

addition of water, and THF was removed on a rotary evapora-

tor. The residue was extracted with DEE (3 ꢀ 150 mL), and the

combined organic layers were washed with water and brine.

After drying over MgSO₄and removal of the solvent under

reduced pressure the crude product was subjected to chroma-

tography on aluminum oxide 90 using PE/DEE = 60:1 f 20:1

as eluent to give the pure product as a yellow solid (9.00 g, 16.00

mmol, 86% yield). Mp: 119 °C. ¹H NMR (400 MHz, CDCl₃): δ

0.13 (s, 9H, Si(CH₃)₃), 3.27 (s, 3H, OCH₃), 4.09-4.12 (m, 1H,

H4), 4.12-4.14 (m, 1H, H2), 4.20 (s, 5H, Cp⁰), 4.24 (t, J = 2.3 Hz,

1H, H3), 5.94 (d, J = 7.6 Hz, 1H, H6), 6.96-7.02 (m, 1H),

7.14-7.37 (m, 13H). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 0.3

(s, Si(CH₃)₃), 57.2 (s, OCH₃), 68.7 (s, C3), 69.0 (s, Cp⁰), 69.1 (s,

C1), 71.7 (d, J = 2.2 Hz, C4), 74.6 (s, C2), 78.6 (d, J = 23.8 Hz,

C6), 95.1 (s, C5), 127.7 (s, 1C), 127.9 (d, J = 5.5 Hz, 1C),

128.2-128.5 (m, 2 ꢀ Ph-meta þ 2C), 128.9 (s, 1C), 133.7 (d, J =

8.2 Hz, Ph-ortho), 133.9 (d, J = 8.3 Hz, Ph-ortho), 134.0 (s, 1C),

136.1 (d, J = 14.2 Hz, C_q), 136.8 (d, J = 10.0 Hz, C_q), 137.2 (d,

J = 10.4 Hz, C_q), 147.2 (d, J = 24.2 Hz, C_q). ³¹P NMR (162

MHz, CDCl₃): δ -16.0 (s). HR-MS (ESI in MeOH/MeCN):

m/z = [M]^þcalcd 560.1591 for C₃₃H₃₅FeOPSi, found 560.1594.

[R]²⁰_λ(nm): þ129.7 (589), þ139.5 (578), þ189.4 (546) (c 0.911,

CH₂Cl₂).

4.33-4.36 (m, 1H, H2), 5.06 (s, 1H, CHOCH₃), 7.20-7.26 (m,

1H, Ph-para), 7.27-7.32 (m, 2H, Ph-meta), 7.34-7.39 (m, 2H,

Ph-ortho). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 56.9 (s,

OCH₃), 64.4 (s, C4), 65.8 (s, C3), 69.7 (s, C2), 71.4 (s, Cp⁰),

77.9 (s, C1), 80.7 (s, CHOCH₃), 90.2 (s, C5), 127.2 (s, Ph-ortho),

127.7 (s, Ph-para), 128.3 (s, Ph-meta), 141.4 (s, Ph-ipso). HR-MS

(ESI in MeOH/MeCN): m/z = [M]^þcalcd 383.9814 for

C

₁₈H₁₇BrFeO, found 383.9821.

rac-(R,S_Fc)-1-Diphenylphosphino-2-(r-methoxyphenylmethyl)-

ferrocene, rac-(R,S_Fc)-21. This compound was obtained as a

yellow solid following a published procedure. Mp: 42-44 °C.

Other analytical data were in accordance with those reported in

ref 11a.

rac-(S,S_Fc)-1-Diphenylphosphino-2-(r-methoxyphenylmethyl)-

ferrocene, rac-(S,S_Fc)-21. A 1.6 M solution of n-BuLi in hexane

(3.22 mL, 5.148 mmol) was added dropwise to a stirred solution

of rac-(S,S_Fc)-20 (1.802 g, 4.680 mmol) in THF (20 mL) at

-78 °C. The resulting mixture was stirred at -78 °C for a further

30 min followed by the dropwise addition of chlorodiphenyl-

phosphine (1.34 g, 6.080 mmol). The mixture was kept at -78 °C

for 15 min and at rt for 1 h. Water was added to quench the

reaction, and DEE caused phase separation. The aqueous phase

was extracted with DEE (2 ꢀ 100 mL), the combined organic

layers were washed with water and brine and dried over MgSO₄,

and the solvents were evaporated. The crude product was crys-

tallized from heptane/toluene followed by short column chro-

matography (aluminum oxide 90, PE/DEE = 16:1 as eluent) to

remove traces of phosphine oxide. The product was obtained as

an orange solid (1.793 g, 3.657 mmol, 78% yield). Mp: 176-

1

179 °C. H NMR (400 MHz, CDCl₃): δ 3.30 (s, 3H, OCH₃),

3.64-3.66 (m, 1H, H2), 4.12 (s, 5H, Cp⁰), 4.27 (t, J = 2.5 Hz, 1H,

H3), 4.63-4.65(m, 1H, H4), 5.22 (d, J = 2.5 Hz, 1H, CHOCH₃),

6.67-6.72 (m, 2H, Ph^B-ortho), 6.90-6.97 (m, 5H, Ph^C-ortho/

meta þ Ph^C-para þ Ph^B-meta), 7.02-7.06 (m, 1H, Ph^B-para),

7.07-7.11 (m, 2H, Ph^C-ortho/meta), 7.34-7.39 (m, 3H, Ph^A-

meta þ Ph^A-para), 7.50-7.54 (m, 2H, Ph^A-ortho). ¹³C{¹H}

NMR (100.6 MHz, CDCl₃): δ 56.5 (s, OCH₃), 68.3 (d, J = 4.3

Hz, C4), 69.1 (s, C3), 69.9 (s, Cp⁰), 71.0 (d, J = 5.5 Hz, C2), 73.5

(d, J = 8.8 Hz, C5), 80.9 (d, J = 8.8 Hz, CHOCH₃), 97.6 (d, J =

24.1 Hz, C1), 127.13 (s, Ph^B/C-para), 127.14 (s, Ph^B/C-para),

127.49 (d, J = 5.7 Hz, Ph^B-meta), 127.51 (s, Ph^C-ortho/meta),

127.7 (s, Ph^C-ortho/meta), 128.0 (d, J = 7.9 Hz, Ph^A-meta), 129.0

(s, Ph^A-para), 131.9 (d, J = 18.7 Hz, Ph^B-ortho), 135.2 (d, J =

20.9 Hz, Ph^A-ortho), 137.4 (d, J = 7.7 Hz, Ph^A-ipso), 138.7 (d,

J = 7.8 Hz, Ph^B-ipso), 141.2 (s, Ph^C-ipso). ³¹P NMR (162 MHz,

CDCl₃): δ -21.5 (s). Ph^Aand Ph^Bconnected to P. HR-MS (ESI

in MeOH/MeCN): m/z = [M]^þcalcd 490.1149 for C₃₀H₂₇FeOP,

found 490.1140.

rac-(R,S_Fc)-1-Trimethylsilyl-2-(r-methoxyphenylmethyl)-

ferrocene, rac-(R,S_Fc)-22. This compound was obtained as a

yellow solid following a published procedure. Mp: 102-104 °C.

Other analytical data were in accordance with those reported in

ref 11a.

rac-(S,S_Fc)-1-Trimethylsilyl-2-(r-methoxyphenylmethyl)ferro-

cene, rac-(S,S_Fc)-22. A 1.6 M solution of n-BuLi in hexane (3.65

mL, 5.839 mmol) was added dropwise to a stirred solution of

rac-(S,S_Fc)-20 (2.044 g, 5.308 mmol) in THF (20 mL) at -78 °C.

The resulting mixture was stirred at -78 °C for a further 30 min

followed by the dropwise addition of chlorotrimethylsilane

(750 mg, 6.900 mmol). The mixture was kept at -78 °C for

15 min and at rt for 1 h. Water was added to quench the reaction,

and DEE caused phase separation. The aqueous phase was

extracted with DEE (2 ꢀ 100 mL), the combined organic layers

were washed with water and brine and dried over MgSO₄, and

the solvents were evaporated. The crude product was purified by

chromatography on aluminum oxide 90 using PE/DEE = 10/:1

as eluent to give the title compound as a red solid (2.092 g, 5.529

mmol, 95% yield). Mp: 62-64 °C. ¹H NMR (400 MHz, CDCl₃):

δ 0.14 (s, 9H, Si(CH₃)₃), 3.39 (s, 3H, OCH₃), 4.03-4.06 (m, 1H,

H2), 4.20 (s, 5H, Cp⁰), 4.30 (t, J = 2.4 Hz, 1H, H3), 4.44-4.46

rac-(R,S_Fc)-1-Bromo-2-(r-methoxyphenylmethyl)ferrocene,

rac-(R,S_Fc)-20. This compound was obtained as a yellow solid

following a published procedure. Mp: 64-68 °C. Other analyt-

ical data were in accordance with those reported in ref 11a.

rac-(S,S_Fc)-1-Bromo-2-(r-methoxy-phenylmethyl)ferrocene,

rac-(S,S_Fc)-20. The product was obtained starting from rac-

(S,S_Fc)-25 (3.518 g, 9.481 mmol) following general procedure B.

Purification involved chromatography on silica using PE/

DEE = 10:1 as eluent to give the title compound as an orange-

red solid (3.247 g, 8.432 mmol, 89% yield). Mp: 99-101 °C.

¹H NMR (400 MHz, CDCl₃): δ 3.41 (s, 3H, OCH₃), 4.07 (t, J =

2.6 Hz, 1H, H3), 4.28 (s, 5H, Cp⁰), 4.25-4.30 (m, 1H, H4),

6454 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

(m, 1H, H4), 4.98 (s, 1H, CHOCH₃), 7.22-7.33 (m, 5H, Ph).

¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 0.3 (s, Si(CH₃)₃), 56.7 (s,

OCH₃), 68.9 (s, C1), 69.0 (s, Cp⁰), 69.3 (s, C3), 70.0 (s, C4), 74.2

(s, C2), 82.1 (s, CHOCH₃), 96.4 (s, C5), 127.6 (s, Ph-para), 128.0

(s, Ph-ortho/meta), 128.1 (s, Ph-ortho/meta), 141.9 (s, Ph-ipso).

HR-MS (ESI in MeOH/MeCN): m/z = [M]^þcalcd 378.1103 for

C₂₁H₂₆FeOSi, found 378.1106.

(d, J = 3.9 Hz, 1H, OH), 4.06-4.10 (m, 2H, H3 þ H4),

4.18-4.21 (m, 1H, H5), 4.24 (s, 5H, Cp⁰), 5.84 (d, J = 3.9 Hz,

1H, H6), 7.08-7.14 (m, 1H, H10), 7.24-7.30 (m, 1H, H11), 7.46

(dd, J = 7.8 Hz, J = 1.7 Hz, 1H, H12), 7.51 (dd, J = 8.0 Hz, J =

1.1 Hz, 1H, H9). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 14.4 (s,

CH₃), 20.8 (s, CH^AH^B), 65.7 (s, C4), 66.6 (s, C3), 68.1 (s, C5),

68.9 (s, Cp⁰), 69.2 (s, C6), 89.8 (s, C1), 92.3 (s, C2), 123.1 (s, C8),

127.5 (s, C11), 128.7 (s, C12), 129.0 (s, C10), 132.6 (s, C9), 142.1

(s, C7). HR-MS (EI 40 °C): m/z = [M]^þcalcd 397.9969 for

C₁₉H₁₉BrFeO, found 397.9966.

rac-(S,S_Fc)-1-Bromo-2-(r-hydroxyphenylmethyl)ferrocene,

rac-(S,S_Fc)-25. A solution of LiTMP in THF (0.73 M, 62.1 mL,

45.30 mmol) was added to a stirred solution of 24 (6.00 g, 22.65

mmol) in THF (20 mL) at -78 °C, and the resulting mixture was

stirred at -78 °C for 30 min. After warming to -30 °C and

stirring for a further 4 h, the red solution was again cooled to

-78 °C and benzaldehyde (7.21 g, 67.95 mmol) was added

dropwise. After stirring at -78 °C for 15 min and at rt for 1 h

the mixture was quenched by the addition of water. DEE was

used for extraction, the combined organic layers were washed

with water and brine and dried over MgSO₄, and the solvents

were removed on a rotary evaporator. The diastereomers

formed (de = 72%) were separated by column chromatography

on aluminum oxide 90 with DCM/PE = 5:1 f 1:0 as eluent to

give rac-(S,S_Fc)-25 (5.844 g, 15.75 mmol, 70% yield) followed by

rac-(R,S_Fc)-25 (1.60 g, 4.30 mmol, 19% yield). Mp: 72-74 °C.

¹H NMR (400 MHz, CDCl₃): δ 2.42 (d, J = 2.2 Hz, 1H, OH),

4.13 (t, J = 2.6 Hz, 1H, H3), 4.26-4.29 (m, 1H, H4), 4.33 (s, 5H,

Cp⁰), 4.47-4.50 (m, 1H, H2), 5.68 (d, J = 2.2 Hz, 1H, CHOH),

7.21-7.27 (m, 1H, Ph-para), 7.27-7.33 (m, 2H, Ph-meta),

7.38-7.43 (m, 2H, Ph-ortho). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): δ 63.9 (s, C4), 66.2 (s, C3), 70.3 (s, C2), 70.6 (s, CHOH),

71.1 (s, Cp⁰), 78.4 (s, C1), 92.4 (s, C5), 126.3 (s, Ph-ortho), 127.6

(s, Ph-para), 128.3 (s, Ph-meta), 142.6 (s, Ph-ipso). HR-MS

(ESI in MeOH/MeCN): m/z = [M]^þcalcd 369.9656 for

C₁₇H₁₅BrFeO, found 369.9645.

rac-(S,R_Fc)-1-Ethyl-2-(r-hydroxy-2-bromophenylmethyl)ferro-

cene, rac-(S,R_Fc)-27. Method A: Lithium chloride (200 mg, 4.718

mmol) was heated to 200 °C for 10 min in vacuo, cooled to rt, and

dissolved in a 2.0 M solution of isopropylmagnesium chloride in

THF (2.30 mL, 4.600 mmol). The resulting mixture was stirred

for 15 min and then cooled to -15 °C. Neat 1,2-dibromobenzene

(1.07 g, 4.544 mmol) was then introduced dropwise by syringe,

and the solution was stirred for 2 h at -15 °C. Aldehyde rac-28

(1.00 g, 4.131 mmol) was dissolved in THF (5 mL) and added

dropwise by cannula to the Grignard reagent at -15 °C. Stirring

was continued for 15 min followed by warming to rt and further

stirring for 30 min. The reaction mixture was then quenched by

the addition of saturated aqueous ammonium chloride solution.

The product was extracted with DEE (2 ꢀ 100 mL), and the

combined organic layers were washed with water and brine and

dried over MgSO₄. The solvents were removed on a rotary

evaporator, and the resulting solid was subjected to column

chromatography on silica gel using PE/EA = 17:3 as eluent to

give rac-(S,R_Fc)-27 as an orange-red oil (1.198 g, 3.002 mmol,

73% yield). Method B: A solution of rac-26 (3.44 g, 11.74 mmol)

in THF (12 mL) was degassed and cooled to -78 °C. Dropwise

addition of a 1.6 M solution of n-BuLi in hexane (7.34 mL, 11.74

mmol) led to the precipitation of a yellow-orange solid, and

stirring was continued for 10 min. In a separate flask, 2-bromo-

benzaldehyde (2.39 g, 12.92 mmol) was dissolved in THF

(5 mL), and the solution was added dropwise at -78 °C to the

lithium intermediate. Stirring was continued for 30 min followed

by warming to rt and further stirring for 1 h. The reaction

mixture was then quenched by the dropwise addition of water.

The product was extracted with EA (2 ꢀ 100 mL), and the com-

bined organic layers were washed with water and brine and dried

over MgSO₄. The solvents were removed on a rotary evapora-

tor, and the residue was chromatographed on aluminum oxide

90 using PE/EA = 17:3 as eluent. rac-(S,R_Fc)-27: R_f= 0.40

(1.78 g, 4.460 mmol, 38% yield). rac-(R,R_Fc)-27: R_f= 0.51 (1.93

g, 4.836 mmol, 41% yield). ¹H NMR (400 MHz, CDCl₃): δ 1.03

(t, J = 7.5 Hz, 3H, CH₃), 2.25-2.49 (m, 2H, CH^AH^B), 2.66

rac-(R,R_Fc)-1-Ethyl-2-(r-hydroxy-2-bromophenylmethyl)ferro-

cene, rac-(R,R_Fc)-27. For synthesis see rac-(S,R_Fc)-27 Method B:

1

The product was obtained as a red solid. Mp: 76-77 °C. H

NMR (400 MHz, CDCl₃): δ 1.10 (t, J = 7.4 Hz, 3H, CH₃),

2.34-2.60 (m, 3H, CH^AH^Bþ OH), 4.12 (bs, 6H, Cp⁰þ H4),

4.16-4.22 (m, 1H, H5), 4.26-4.32 (m, 1H, H3), 5.89 (d, J=2.1Hz,

1H, H6), 7.11-7.18 (m, 1H, H10), 7.31-7.38 (m, 1H, H11), 7.56

(dd, J = 8.0 Hz, J = 0.9 Hz, 1H, H9), 7.69 (dd, J = 7.8 Hz, J =

1.5 Hz, 1H, H12). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 14.6 (s,

CH₃), 21.0 (s, CH^AH^B), 66.4 (s, C4), 68.4 (s, C5), 68.9 (s, C3),

69.4 (s, Cp⁰), 71.2 (s, C6), 89.9 (s, C1 þ C2), 122.8 (s, C8), 127.3

(s, C11), 128.8 (s, C12), 128.9 (s, C10), 132.9 (s, C9), 141.7 (s,

C7). HR-MS (EI, 30 °C): m/z = [M]^þcalcd 397.9970 for

C₁₉H₁₉BrFeO, found 397.9960.

rac-2-Ethylferrocenylcarbaldehyde, rac-28. A solution of rac-

26 (2.00 g, 6.826 mmol) in THF (10 mL) was degassed and

cooled to -78 °C. Addition of a 1.6 M solution of n-BuLi in

hexane (4.69 mL, 7.509 mmol) led to the precipitation of a

yellow solid. After stirring for 30 min, DMF (1.00 mL) was

added dropwise, and the mixture was warmed to rt. Stirring was

continued for an additional 1 h, and the reaction was quenched

by the addition of water. The product was extracted with DEE

(2 ꢀ 50 mL), the combined organic layers were washed with

water and brine, and the solvent was removed under reduced

pressure. Chromatography on aluminum oxide 90 using PE/EA

= 7:3 as eluent afforded the title compound as a red oil (1.537 g,

6.348 mmol, 93% yield). ¹H NMR (400 MHz, CDCl₃): δ 1.21 (t,

J = 7.5 Hz, 3H, CH₃), 2.58-2.76 (m, 2H, CH^AH^B), 4.21 (s, 5H,

Cp⁰), 4.46-4.49 (m, 1H, H4), 4.50-4.53 (m, 1H, H5), 4.70-4.73

(m, 1H, H3), 10.09 (s, 1H, CHO). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): δ 15.3 (s, CH₃), 21.1 (s, CH^AH^B), 69.8 (s, C3), 70.0 (s,

Cp⁰), 71.0 (s, C4), 73.0 (s, C5), 76.5 (s, C2), 94.0 (s, C1), 193.7 (s,

CHO). HR-MS (EI, 30 °C): m/z = [M]^þcalcd 242.0394 for

C₁₃H₁₄FeO, found 242.0389.

rac-(S,R_Fc)-1-Ethyl-2-(r-methoxy-2-bromophenylmethyl)ferro-

cene, rac-(S,R_Fc)-29. The compound was obtained starting from

rac-(S,R_Fc)-27 (2.00 g, 5.011 mmol) following general procedure

B. Purification involved chromatography on aluminum oxide

90 using PE/EA = 20:1 as eluent to give the title compound as

1

an orange-red oil (1.428 g, 3.457 mmol, 69% yield). H NMR

(400 MHz, CDCl₃): δ 0.94 (t, J = 7.5 Hz, 3H, CH₃), 2.14-2.26

(m, 1H, CH^AH^B), 2.37-2.49 (m, 1H, CH^AH^B), 3.42 (s, 3H,

OCH₃), 3.97-4.02 (m, 1H, H4), 4.03-4.07 (m, 1H, H5),

4.09-4.14 (m, 1H, H3), 4.17 (s, 5H, Cp⁰), 5.57 (s, 1H, H6),

7.07-7.12 (m, 1H, H10), 7.24-7.30 (m, 1H, H11), 7.38 (dd, J =

7.8 Hz, J = 1.8 Hz, 1H, H12), 7.50 (dd, J = 8.0 Hz, J = 1.2 Hz,

1H, H9). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 14.1 (s, CH₃),

21.0 (s, CH^AH^B), 56.9 (s, OCH₃), 65.1 (s, C4), 66.8 (s, C3), 67.4

(s, C5), 69.3 (s, Cp⁰), 79.2 (s, C6), 88.5 (s, C1/C2), 88.9 (s, C1/C2),

124.1 (s, C8), 127.8 (s, C11), 129.0 (s, C10), 129.6 (s, C12), 132.2

(s, C9), 140.0 (s, C7). HR-MS (EI, 30 °C): m/z = [M]^þcalcd

412.0127 for C₂₀H₂₁BrFeO, found 412.0122.

rac-(R,R_Fc)-1-Ethyl-2-8r-methoxy-2-bromophenylmethyl)ferro-

cene, rac-(R,R_Fc)-29. The complex was obtained starting from

rac-(R,R_Fc)-27 (2.00 g, 5.011 mmol) following general procedure

B. Purification involved chromatography on aluminum oxide

90 using PE/EA = 20:1 as eluent to give the title compound as

1

an orange-red oil (1.364 g, 3.302 mmol, 66% yield). H NMR

(400 MHz, CDCl₃): δ 1.24 (t, J = 7.5 Hz, 3H, CH₃), 2.53-2.60

(m, 2H, CH^AH^B), 3.20 (s, 3H, OCH₃), 3.90 (s, Cp’), 4.01-4.03

Article

Organometallics, Vol. 29, No. 23, 2010 6455

(m, 1H, H3), 4.04-4.08 (m, 1H, H4), 4.15-4.19 (m, 1H, H5),

5.64 (s, 1H, H6), 7.18-7.24 (m, 1H, H10), 7.38-7.44 (m, 1H,

H11), 7.62-7.68 (m, 2H, H9 þ H12). ¹³C{¹H} NMR (100.6

MHz, CDCl₃): δ 14.7 (s, CH₃), 21.0 (s, CH^AH^B), 56.6 (s, OCH₃),

66.3 (s, C3), 66.4 (s, C4), 67.9 (s, C5), 69.1 (s, Cp⁰), 79.1 (s, C6),

85.9 (s, C2), 90.2 (s, C1), 124.2 (s, C8), 127.5 (s, C11), 129.1 (s,

C10), 129.3 (s, C12), 132.5 (s, C9), 140.6 (s, C7). HR-MS (EI,

30 °C): m/z = [M]^þcalcd 412.0127 for C₂₀H₂₁BrFeO, found

412.0118.

CDCl₃):δ42.6 (d, J=28.0Hz,C6),67.0(s,C3),67.6(d,J=2.9Hz,

C4), 68.3 (s, C2), 71.2 (s, Cp⁰), 82.1 (d, J = 4.0 Hz, C1/C5),

86.0 (d, J = 6.7 Hz, C1/C5), 127.42 (d, J = 2.0 Hz, Ph^C-para),

127.44 (d, J = 52.8 Hz, Ph^A/B-ipso), 127.8 (s, Ph^C-meta), 127.9

(d, J = 9.5 Hz, Ph^B-meta), 128.4 (d, J = 9.8 Hz, Ph^A-meta),

130.6 (d, J = 5.3 Hz, Ph^C-ortho), 130.8 (d, J = 2.5 Hz,

Ph^B-para), 131.3 (d, J = 2.3 Hz, Ph^A-para), 133.2 (d, J = 8.5

Hz, Ph^B-ortho), 133.5 (d, J = 8.4 Hz, Ph^A-ortho), 138.8 (d, J =

1.6 Hz, Ph^C-ipso). Ph^A/B-ipso not observed. ³¹P NMR (162

MHz, CDCl₃): δ 26.9 (bs). HR-MS (ESI in MeOH/MeCN):

m/z = [M]^þcalcd 552.0484 for C₂₉H₂₇BBrFeP, found 552.0475.

rac-(S,S_Fc)-1-Bromo-2-[r-(diphenylphosphino-KP)phenylmethyl]-

ferrocene Trihydridoboron, rac-(S,S_Fc)-33(BH₃). This compound

was obtained starting from rac-(S,S_Fc)-20 (200 mg, 0.5194 mmol)

following general procedure A (80 °C, 18 h). Purification involved

crystallization three times from EA to give the compound as orange

crystals suitable for X-ray diffraction (156 mg, 0.2821 mmol, 54%

(S,S_Fc)-1-Trimethylsilyl-2-(r-hydroxy-2-bromophenylmethyl)-

ferrocene, (S,S_Fc)-31. A 1.3 M solution of isopropylmagnesium

chloride/lithium chloride complex in THF (60 mL, 78.00 mmol)

was cooled to -15 °C, and 1,2-dibromobenzene (18.40 g, 78.00

mmol) was added dropwise. Stirring was continued for 2 h at

-15 °C followed by the slow addition of a solution of aldehyde

(S_Fc)-30 (15.04 g, 52.55 mmol) in THF (60 mL). After complete

addition, stirring was continued for 30 min at -15 °C and for 1 h

at rt. The reaction mixture was quenched by the careful addition

of saturated aqueous ammonium chloride solution, and THF

was removed on a rotary evaporator. The residue was extracted

with DEE (2 ꢀ 300 mL), and the combined organic layers were

washed with water and brine and dried over MgSO₄. Chro-

matography on aluminum oxide 90 using PE/EA = 20:1 as

eluent afforded the product with an ee > 90%. Recrystallization

from heptane gave the pure product as a red oil with ee > 99.8%

(13.95 g, 31.46 mmol, 60% yield). ¹H NMR (400 MHz, CDCl₃):

δ 0.13 (s, 9H, Si(CH₃)₃), 2.56 (d, J = 3.9 Hz, 1H, OH),

4.17-4.19 (m, 1H, H2), 4.26 (s, 5H, Cp’), 4.38 (t, J = 2.3 Hz,

1H, H3), 4.43-4.45 (m, 1H, H4), 5.85 (d, J = 3.9 Hz, 1H, H6),

7.08-7.14 (m, 1H, H10), 7.18-7.22 (m, 2H, H11 þ H12), 7.53

(d, J = 8.0 Hz, 1H, H9). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ

0.1 (s, Si(CH₃)₃), 68.7 (s, Cp⁰), 69.6 (s, C3), 70.3 (s, C4), 70.7 (s,

C6), 70.9 (s, C1), 74.9 (s, C2), 97.3 (s, C5), 123.9 (s, C8), 127.3 (s,

C11), 129.6 (s, C10 þ C12), 132.7 (s, C9), 142.3 (s, C7). HR-MS

(ESI in MeOH/MeCN): m/z = [M]^þcalcd 442.0053 for

1

yield). Mp: 185-187 °C (dec). H NMR (400 MHz, CDCl₃): δ

0.70-2.03 (bs, 3H, BH₃), 3.78 (s, 5H, Cp⁰), 4.19-4.23 (m, 1H, H3),

4.36-4.42 (m, 1H, H2), 4.97-5.03 (m, 1H, H4), 5.13 (d, J = 16.9

Hz, 1H, H6), 6.90-6.98 (m, 3H, Ph^C-meta þ Ph^C-para), 7.00-7.12

(m, 4H, Ph^B-meta þ Ph^C-ortho), 7.15 7.23 (m, 1H, Ph^B-para),

7.23-7.30 (m, 2H, Ph^B-ortho), 7.61-7.74 (m, 3H, Ph^A-meta þ

Ph^A-para), 8.33-8.42 (m, 2H, Ph^A-ortho). ¹³C{¹H} NMR (100.6

MHz, CDCl₃):δ41.6 (d, J= 32.7 Hz, C6), 66.3 (s, C3), 67.7 (s, C4),

69.1 (s, C2), 71.6 (s, Cp⁰), 80.3 (d, J = 11.6 Hz, C1/C5), 85.9 (d,

J = 5.9 Hz, C1/C5), 126.6 (d, J = 2.2 Hz, Ph^C-para), 127.68 (bs,

Ph^C-meta), 127.73 (d, J=9.6Hz,Ph-^Bmeta), 128.8 (d, J= 52.4 Hz,

Ph^A-ipso), 129.2 (d, J = 9.5 Hz, Ph^A-meta), 129.6 (d, J = 4.3 Hz,

Ph^C-ortho), 130.3 (d, J = 2.2 Hz, Ph^B-para), 131.9 (d, J = 2.2 Hz,

Ph^A-para), 132.7 (d, J = 8.2 Hz, Ph^B-ortho), 133.3 (d, J = 8.4 Hz,

Ph^A-ortho), 137.8 (s, Ph^C-ipso). Ph^B-ipso not observed. Ph^Aand

Ph^Bconnected to P. ³¹P NMR (162 MHz, CDCl₃): δ 21.0 (bs).

HR-MS (ESI in MeOH/MeCN): m/z = [M]^þcalcd 552.0484 for

C₂₉H₂₇BBrFeP, found 552.0480.

C₂₀H₂₃BrFeOSi, found 442.0059. [R]²⁰(nm): þ56.5 (589),

rac-(R,S_Fc)-1-Diphenylphosphino-2-[r-(diphenylphosphino-KP)-

phenylmethyl]ferrocene Trihydridoboron, rac-(R,S_Fc)-34(BH₃).

This compound was obtained starting from rac-(R,S_Fc)-21 (200

mg, 0.4081 mmol) following general procedure A (80 °C, 18 h).

Purification involved chromatography on aluminum oxide 90

using PE/DEE = 4:1 f 2:1 as eluent togivethe title compound as

a yellow foam (175 mg, 0.2659 mmol, 65% yield). Mp: 102-

104 °C. NMR data were in accordance with those reported in

ref 16.

λ

þ61.5 (578), þ85.8 (546) (c 0.660, CH₂Cl₂). HPLC (OD-H,

8% i-PrOH, 0.6 mL/min, 254 nm): t_r/min = 8.4 (S,S_Fc), 10.4

(R,R_Fc).

(S,S_Fc)-1-Trimethylsilyl-2-(r-methoxy-2-bromophenylmethyl)-

ferrocene, (S,S_Fc)-32. The complex was obtained starting from

(S,S_Fc)-31 (13.95 g, 31.46 mmol) following general procedure B.

Purification involved chromatography on aluminum oxide 90

using PE/EA = 40:1 as eluent to give the title compound as a red

1

rac-(S,S_Fc)-1-Diphenylphosphino-2-[r-(diphenylphosphino-KP)-

phenylmethyl]ferrocene Trihydridoboron, rac-(S,S_Fc)-34(BH₃).

This compound was obtained starting from rac-(S,S_Fc)-21

(500 mg, 1.020 mmol) following general procedure A (80 °C,

18 h). Purification involved crystallization twice from EA to give

the compound as orange crystals (389 mg, 0.5787 mmol, 57%

yield). Mp: >230 °C (dec). ¹H NMR (400 MHz, CDCl₃): δ

0.74-2.42 (bs, 6H, 2 ꢀ BH₃), 3.67 (s, 5H, Cp⁰), 3.72-3.75 (m,

1H, H4), 4.51-4.55 (m, 1H, H3), 5.71-5.75 (m, 1H, H2), 5.77

(d, J = 17.5 Hz, 1H, H6), 5.70-7.30 (bs, 4H, Ph), 6.55-6.64 (m,

1H, Ph), 6.75-6.84 (m, 4H, Ph), 6.90-6.98 (m, 2H, Ph),

7.00-7.10 (m, 2H, Ph), 7.10-7.18 (m, 2H, Ph), 7.35-7.42 (m,

2H, Ph), 7.43-7.49 (m, 1H, Ph), 7.50-7.60 (m, 2H, Ph),

7.63-7.70 (m, 1H, Ph), 7.72-7.80 (m, 2H, Ph), 8.64-8.74 (m,

2H, Ph). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 39.9 (d, J =

30.8 Hz, C6), 67.7 (dd, J = 64.9 Hz, J = 10.9 Hz, C1), 70.7 (s,

Cp⁰), 70.8 (d, J = 6.4 Hz, C3), 72.8 (d, J = 3.2 Hz, C4), 74.2 (d,

J = 7.0 Hz, C2), 91.9 (dd, J = 15.2 Hz, J = 5.3 Hz, C5), 125.9

(d, J = 2.7 Hz, Ph-para), 126.9 (bs, Ph-ortho/meta), 127.5 (d,

J = 9.9 Hz, Ph-meta), 127.7 (d, J = 10.2 Hz, Ph-meta), 128.1 (d,

J = 10.3 Hz, Ph-meta), 128.5 (d, J = 49.7 Hz, Ph-ipso), 129.0 (d,

J = 55.8 Hz, Ph-ipso), 129.0-129.5 (bs, Ph-ortho/meta), 129.1

(d, J = 9.8 Hz, Ph-meta), 129.8 (d, J = 2.3 Hz, Ph-para), 129.9

(d, J = 2.2 Hz, Ph-para), 130.6 (d, J = 58.6 Hz, Ph-ipso), 130.7

(d, J = 59.7 Hz, Ph-ipso), 131.0 (d, J = 2.4 Hz, Ph-para), 131.8

(d, J = 9.1 Hz, Ph-ortho), 132.0 (d, J = 2.3 Hz, Ph-para), 132.4

solid (13.40 g, 29.30 mmol, 93% yield). Mp: 88 °C. H NMR

(400 MHz, CDCl₃): δ 0.16 (s, 9H, Si(CH₃)₃), 3.55 (s, 3H, OCH₃),

4.12-4.14 (m, 1H, H2), 4.14-4.16 (m, 1H, H4), 4.20 (s, 5H,

Cp⁰), 4.27 (t, J = 2.3 Hz, 1H, H3), 5.42 (s, 1H, H6), 7.10-7.16

(m, 1H, H10), 7.25-7.30 (m, 2H, H11, H12), 7.54 (d, J = 8.0,

1H, H9). ¹³C{¹H} NMR (100.6 MHz, CDCl₃): δ 0.2 (s, Si-

(CH₃)₃), 57.7 (s, OCH₃), 68.9 (s, Cp⁰), 69.0 (s, C3), 69.3 (s, C1),

71.3 (s, C4), 74.7 (s, C2), 79.9 (s, C6), 94.5 (s, C5), 124.3 (s, C8),

127.3 (s, C11), 129.1 (s, C10), 129.7 (s, C12), 132.5 (s, C9), 141.2

(s, C7). HR-MS (ESI in MeOH/MeCN): m/z = [M]^þcalcd

456.0209 for C₂₁H₂₅BrFeOSi, found 456.0215. [R]²⁰(nm):

λ

þ109.1 (589), þ117.7 (578), þ163.9 (546) (c 0.894, CH₂Cl₂).

rac-(R,S_Fc)-1-Bromo-2-[r-(diphenylphosphino-KP)phenylmethyl]-

ferrocene Trihydridoboron, rac-(R,S_Fc)-33(BH₃). This com-

pound was obtained starting from rac-(R,S_Fc)-20 (200 mg,

0.5194 mmol) following general procedure A (80 °C, 18 h).

Purification involved chromatography on aluminum oxide 90

using PE/DEE = 4:1 f 2:1 as eluent to give the title compound

as a yellow foam (216 mg, 0.3906 mmol, 75% yield). Mp:

1

153-154 °C (dec). H NMR (400 MHz, CDCl₃): δ 0.60-1.65

(bs, 3H, BH₃), 3.61 (s, 5H, Cp⁰), 4.18-4.21 (m, 1H, H3), 4.24-

4.28 (m, 1H, H2), 4.76-4.81 (m, 1H, H4), 4.80 (d, J = 17.2 Hz,

1H, H6), 7.17-7.25 (m, 3H, Ph^B-meta þ Ph^C-para), 7.28-7.42

(m, 7H, Ph^A-meta þ Ph^B-ortho þ Ph^C-meta þ Ph^B-para),

7.41-7.47 (m, 1H, Ph^A-para), 7.53-7.61 (m, 2H, Ph^C-ortho),

7.72-7.80 (m, 2H, Ph^A-ortho). ¹³C{¹H} NMR (100.6 MHz,

6456 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

(d, J = 8.2 Hz, Ph-ortho), 133.4 (d, J = 9.9 Hz, Ph-ortho),

134.4 (d, J = 8.5 Hz, Ph-ortho), 137.4 (s, Ph-ipso). ³¹P NMR

(162 MHz, CDCl₃): δ 13.3 (bs, C1-P), 22.6 (bs, C6-P). HR-MS

(ESI in MeOH/MeCN): m/z = [M]^þcalcd 672.2156 for

C₄₁H₄₀B₂FeP₂, found 672.2161.

rac-(R,S_Fc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)-

phenylmethyl]ferrocene trihydridoboron, rac-(R,S_Fc)-35(BH₃).

This compound was obtained starting from rac-(R,S_Fc)-22

(200 mg, 0.5289 mmol) following general procedure A (60 °C,

24 h). Purification involved chromatography on aluminum

oxide 90 using PE/DEE = 10/:1 f 2:1 as eluent to give the title

compound as a yellow foam (196 mg, 0.3589 mmol, 68% yield).

Mp: 65-66 °C. NMR data were in accordance with those

reported in ref 16.

rac-(S,S_Fc)-1-Trimethylsilyl-2-[r-(diphenylphosphino-KP)phe-

nylmethyl]ferrocene Trihydridoboron, rac-(S,S_Fc)-35(BH₃). This

compound was obtained starting from rac-(S,S_Fc)-22 (700 mg,

1.850 mmol) following general procedure A (60 °C, 24 h).

Attempts to purify this compound were unsuccessful, but the

desired product could be identified by NMR spectroscopy. ¹H

NMR (400 MHz, CDCl₃): δ -0.06 (s, 9H, C(CH₃)₃), 0.62-

1.91 (bs, 3H, BH₃), 3.79 (s, 5H, Cp⁰), 3.99-4.02 (m, 1H, H2),

4.39-4.43 (m, 1H, H3), 4.99 (d, J = 15.4 Hz, 1H, H6), 5.20-

5.24 (m, 1H, H4), 6.58-6.65 (m, 2H, Ph^C-ortho), 6.85-6.92 (m,

2H, Ph^C-meta), 6.93-7.00 (m, 1H, Ph^C-para), 7.06-7.27 (m,

5H, Ph^B-ortho þ Ph^B-meta þ Ph^B-para), 7.58-7.68 (m, 3H,

Ph^A-meta þ Ph^A-para), 8.19-8.27 (m, 2H, Ph^A-ortho). ¹³C{¹H}

NMR (100.6 MHz, CDCl₃): δ 0.1 (s, C(CH₃)₃), 45.2 (d, J = 27.5

Hz, C6), 69.3 (s, Cp⁰), 70.1 (s, C3), 70.5 (d, J = 10.7 Hz, C1), 73.4

(d, J = 3.9 Hz, C4), 74.0 (s, C2), 92.1 (d, J = 4.2 Hz, C5), 126.5

(d, J = 2.5 Hz, Ph^C-para), 127.4 (d, J = 2.1 Hz, Ph^C-meta),

127.7 (d, J = 9.7 Hz, Ph^B-meta), 128.7 (d, J = 50.1 Hz,

Ph^A-ipso), 128.9 (d, J = 9.5 Hz, Ph^A-meta), 129.2 (d, J =

54.4 Hz, Ph^B-ipso), 130.1 (d, J = 3.8 Hz, Ph^C-ortho), 130.4 (d,

J = 2.2 Hz, Ph^B-para), 131.7 (d, J = 2.3 Hz, Ph^A-para), 133.2 (d,

J = 7.6 Hz, Ph^B-ortho), 133.7 (d, J = 8.3 Hz, Ph^A-ortho), 139.2

(d, J = 2.2 Hz, Ph^C-ipso). ³¹P NMR (162 MHz, CDCl₃): δ 22.9

(bs). Ph^Aand Ph^Bconnected to P.

connected to C2-CH-P. ³¹P NMR (162 MHz, CDCl₃): δ -23.4

(d, J = 9.8 Hz, C1-P), 0.6 (d, J = 9.8 Hz, C2-CH-P). HR-MS

(ESI in MeOH/MeCN): m/z = [M þ H^þ]^þcalcd 583.1407 for

C₃₆H₃₃FeP₂, found 583.1399. [R]²⁰_λ(nm): þ295.8 (589), þ319.6

(578), þ416.8 (546) (c 0.935, CHCl₃).

(R,R_Fc)-1-Diphenylphosphino-2-(1-dicyclohexylphosphinoethyl)-

ferrocene, (R,R_Fc)-36b. To a solution of (R,R_Fc)-11 (2.00 g, 4.532

mmol) in distilled and degassed acetic acid (20 mL) was added

dicyclohexylphosphine (1.08 g, 5.438 mmol), and the resulting

mixture was degassed three times. After heating to 80 °C over-

night, the solvent was removed under reduced pressure and the

remaining yellow solid redissolved in a minimum amount of

DCM. An aliquot was analyzed by ¹H NMR, which indicated

full conversion and complete retention of configuration. The

solvent was again removed under reduced pressure, and the

crude product was chromatographed under inert conditions on

aluminum oxide 90 using PE/EA = 20:1 as eluent. The pure

compound was obtained as a yellow foam (2.57 g, 4.323 mmol,

1

95% yield). Mp: 53-57 °C. H NMR (400 MHz, CDCl₃): δ

1.15-1.48 (m, 11H, Cy), 1.23 (dd, J = 7.3 Hz, J = 5.7 Hz, 3H,

CHCH₃), 1.63-1.95 (m, 11H, Cy), 3.11-3.21 (m, 1H, CHCH₃),

3.89-3.93 (m, 1H, H5), 3.98 (s, 5H, Cp⁰), 4.27-4.31 (m, 1H,

H4), 4.36-4.39 (m, 1H, H3), 7.16-7.25 (m, 5H, Ph^B-ortho þ

Ph^B-meta þ Ph^B-para), 7.34-7.40 (m, 3H, Ph^A-meta þ Ph^A-

para), 7.55-7.63 (m, 2H, Ph^A-ortho). ¹³C{¹H} NMR (100.6

MHz, CDCl₃): δ 21.5 (d, J = 7.3 Hz, CHCH₃), 26.4-26.8 (m,

CHCH₃þ Cy), 27.3-27.9 (m, Cy), 29.2 (d, J = 6.9 Hz, Cy), 30.0

(d, J = 9.8 Hz, Cy), 31.1-31.5 (m, Cy), 33.1-33.6 (m, Cy), 69.2

(s, C4), 69.7 (d, J = 2.1 Hz, Cp’), 71.3 (dd, J = 4.4 Hz, J = 1.5

Hz, C5), 71.9 (dd, J = 10.8 Hz, J = 4.7 Hz, C3), 73.9 (dd, J =

10.6 Hz, J = 5.9 Hz, C1), 101.6 (dd, J = 26.5 Hz, J = 18.1 Hz,

C2), 127.4 (s, Ph^B-para), 127.8 (d, J = 5.9 Hz, Ph^A/B-meta), 127.9

(d, J = 8.0 Hz, Ph^A/B-meta), 129.0 (s, Ph^A-para), 132.4 (d, J =

17.5 Hz, Ph^B-ortho), 135.4 (d, J = 22.1 Hz, Ph^A-ortho), 138.7 (d,

J = 8.9 Hz, Ph^A-ipso), 141.1 (d, J = 8.8 Hz, Ph^B-ipso). ³¹P NMR

(162 MHz, CDCl₃): δ -24.3 (d, J = 8.5 Hz, PPh₂), 9.0 (d, J = 8.5

Hz, PCy₂). HR-MS (ESI in MeOH/MeCN): m/z = [M þ H^þ]^þ

calcd 595.2347 for C₃₆H₄₅FeP₂, found 595.2354. [R]²⁰(nm):

λ

(R,R_Fc)-1-Diphenylphosphino-2-(1-diphenylphosphinoethyl)ferro-

cene, (R,R_Fc)-36a. To a solution of (R,R_Fc)-11 (1.55 g, 3.512

mmol) in distilled and degassed acetic acid (20 mL) was added

diphenylphosphine (785 mg, 4.215 mmol), and the resulting

mixture was degassed three times. After heating to 80 °C over-

night, the solvent was removed under reduced pressure and the

remaining yellow solid was redissolved in a minimum amount of

DCM. An aliquot was analyzed by ¹H NMR, and this indicated

full conversion and complete retention of configuration. The

solvent was again removed under reduced pressure, and the

crude product was chromatographed under inert conditions on

aluminum oxide 90 using PE/EA = 1:0 f 20:1 as eluent. The

pure compound was obtained as a yellow foam (1.81 g, 3.108

mmol, 88% yield). Mp: 54-64 °C. ¹H NMR (400 MHz, CDCl₃):

δ 1.10 (dd, J = 9.7 Hz, J = 7.2 Hz, 3H, CHCH₃), 3.65-3.79 (m,

1H, CHCH₃), 3.86 (s, 5H, Cp⁰), 3.85-3.88 (m, 1H, H5),

4.23-4.27 (m, 2H, H3 þ H4), 7.20-7.25 (m, 5H, Ph^D-ortho þ

Ph^D-meta þ Ph^D-para), 7.28-7.35 (m, 4H, Ph^B-meta þ

Ph^B-para þ Ph^C-para), 7.36-7.42 (m, 5H, Ph^A-meta þ Ph^C-

meta þ Ph^A-para), 7.48-7.55 (m, 2H, Ph^B-ortho), 7.56-7.67

(m, 4H, Ph^A-ortho þ Ph^C-ortho). ¹³C{¹H} NMR (100.6 MHz,

CDCl₃): δ 22.1 (dd, J = 9.1 Hz, J = 6.1 Hz, CHCH₃), 30.3 (dd,

J = 15.4 Hz, J = 7.4 Hz, CHCH₃), 69.3 (s, C4), 69.8 (d, J = 1.4

Hz, Cp⁰), 70.7-70.8 (m, C5), 71.1 (dd, J = 7.5 Hz, J = 4.6 Hz,

C3), 74.5 (dd, J = 9.8 Hz, J = 5.5 Hz, C1), 99.3 (dd, J =

26.1 Hz, J = 18.2 Hz, C2), 127.7 (s, 1C, Ph), 127.8-128.3 (m,

9C, Ph), 128.8 (s, 1C, Ph), 129.0 (s, 1C, Ph), 132.6 (d, J = 18.0

Hz, Ph^D-ortho), 133.1 (dd, J = 18.1 Hz, J = 2.0 Hz, Ph^C-ortho),

134.9 (d, J = 20.9 Hz, Ph^B-ortho), 135.2 (d, J = 21.6 Hz,

Ph^A-ortho), 138.2 (d, J = 19.4 Hz, Ph-ipso), 138.4 (d, J =

9.0 Hz, Ph-ipso), 139.0 (d, J = 15.0 Hz, Ph-ipso), 140.4 (d, J =

9.0 Hz, Ph-ipso). Ph^Aþ Ph^Dconnected to C1-P, Ph^Bþ Ph^C

þ327.1 (589), þ353.0 (578), þ462.8 (546) (c 0.836, CHCl₃).

(R,R_Fc)-1-(Diphenylphosphino-KP)-2-[1-(di-tert-butylphosphino-

KP)ethyl]ferrocene Hexahydridodiboron, (R,R_Fc)-36c(BH₃)₂. To

a solution of (R,R_Fc)-11 (2.00 g, 4.532 mmol) in distilled and

degassed acetic acid (20 mL) was added di-tert-butylphosphine

(795 mg, 5.438 mmol), and the resulting mixture was degassed

three times. After heating to 80 °C overnight, the solvent was

removed under reduced pressure and the remaining yellow solid

was redissolved in a minimum amount of DCM. An aliquot was

1

analyzed by H NMR, and this indicated full conversion and

retention of configuration with de = 84%. The solvent was

again removed under reduced pressure, and a solution of borane

in THF was added (1.0 M, 22.66 mL, 22.66 mmol). After stirring

at rt for 4 h, water was added dropwise to quench the excess

borane and the solution was extracted with EA. The combined

organic layers were washed with water and brine and dried over

MgSO₄, and the solvents were removed on a rotary evaporator.

The pure product was crystallized from EA as orange crystals

1

(896 mg, 1.572 mmol, 35% yield). Mp: 192-196 °C (dec). H

NMR (400 MHz, CDCl₃): δ 0.32-2.13 (bs, 6H, 2 ꢀ BH₃), 1.28

(dd, J = 9.5 Hz, J = 7.4 Hz, 3H, CHCH₃), 1.38 (d, J = 12.4 Hz,

9H, C^B(CH₃)₃), 1.45 (d, J = 12.4 Hz, 9H, C^A(CH₃)₃), 4.01-4.05

(m, 1H, H5), 4.03-4.14 (m, 1H, CHCH₃), 4.13 (s, 5H, Cp⁰),

4.47-4.50 (m, 1H, H4), 5.03-5.07 (m, 1H, H3), 7.33-7.51 (m,

6H, Ph^A-meta þ Ph^A-para þ Ph^B-meta þ Ph^B-para), 7.55-7.65

(m, 2H, Ph^B-ortho), 7.70-7.80 (m, 2H, Ph^A-ortho). ¹³C{¹H}

NMR (100.6 MHz, CDCl₃): δ 26.0 (d, J = 5.4 Hz, CHCH₃),

28.2 (d, J = 24.3 Hz, CHCH₃), 28.4 (s, C^A(CH₃)₃), 30.1 (s,

C^B(CH₃)₃), 35.1 (d, J = 20.7 Hz, C^A/B(CH₃)₃), 35.2 (d, J = 27.6

Hz, C^A/B(CH₃)₃), 63.0 (dd, J = 62.8 Hz, J = 10.5 Hz, C1), 70.0

(d, J = 6.5 Hz, C4), 70.1 (s, Cp⁰), 72.3 (d, J = 2.7 Hz, C5), 75.1

(d,J=6.3Hz,C3),98.8(d,J= 14.9 Hz, C2), 128.1 (d, J= 10.1 Hz,

Article

Organometallics, Vol. 29, No. 23, 2010 6457

Ph^A-meta), 128.4 (d, J = 9.9 Hz, Ph^B-meta), 130.6 (d, J =

2.2 Hz, Ph^A/B-para), 130.9 (d, J = 2.2 Hz, Ph^A/B-para), 131.0 (d,

J = 62.8 Hz, Ph^A/B-ipso), 132.2 (d, J = 9.1 Hz, Ph^B-ortho), 132.6

(d, J = 55.6 Hz, Ph^A/B-ipso), 133.7 (d, J = 9.2 Hz, Ph^A-ortho).

³¹P NMR (162 MHz, CDCl₃): δ 13.6 (bs, PPh₂), 53.1 (bs, P-t-Bu₂).

HR-MS (ESI in MeOH/MeCN): m/z = [M þ Na^þ]^þcalcd

(d, J = 12.0 Hz, Ph^A-meta), 129.1 (d, J = 10.3 Hz, Ph^D-meta),

130.4 (d, J = 3.0 Hz, Ph^B-para), 131.1 (d, J = 3.1 Hz, Ph^C-para),

131.8 (d, J = 2.3 Hz, Ph^A-para), 131.9-132.0 (m, C11 þ Ph^D-

para), 132.8 (d, J = 61.5 Hz, Ph^B-ipso), 132.9 (d, J = 10.2 Hz,

Ph^B-ortho), 134.2-134.4 (m, C12 þ Ph^C-ortho), 135.2-135.4

(m, Ph^D-ortho), 136.3 (d, J = 11.0 Hz, Ph^A-ortho), 137.3 (d, J =

2.2 Hz, C9), 148.0 (dd, J = 14.4 Hz, J = 4.3 Hz, C7). ³¹P NMR

(243 MHz, CDCl₃): δ 17.6 (d, J = 20.2 Hz, C8-P), 35.9 (d, J =

20.2 Hz, C6-P). Ph^Aþ Ph^Bconnected to C8-P, Ph^Cþ Ph^D

593.2520 for C₃₂H₄₆B₂FeNaP₂, found 593.2506. [R]²⁰(nm):

λ

þ257.3 (589), þ277.7 (578), þ365.5 (546) (c 0.636, CHCl₃).

(R,R_Fc)-1-Diphenylphosphino-2-(1-di-tert-butylphosphinoethyl)-

ferrocene, (R,R_Fc)-36c. A degassed suspension of (R,R_Fc)-36c-

(BH₃)₂(820 mg, 1.438 mmol) in morpholine (15 mL) was heated

to 100 °C for 3 h. After cooling, the morpholine was removed

under reduced pressure and the residue was extracted with DEE.

The combined organic layers were washed with degassed 5%

aqueous citric acid solution and degassed brine and dried over

MgSO₄. The solvent was removed on a rotary evaporator, and

the crude product was purified by chromatography under inert

conditions on aluminum oxide 90 using PE/DEE = 1:1 as eluent

to give the title compound as a yellow foam (724 mg, 1.335

mmol, 93% yield). Mp: 52-56 °C. ¹H NMR (400 MHz, CDCl₃):δ

1.29 (d, J = 11.0 Hz, 9H, C^B(CH₃)₃), 1.30 (dd, J = 7.6 Hz, J =

3.0 Hz, 3H, CHCH₃), 1.35 (d, J = 10.6 Hz, 9H, C^A(CH₃)₃),

3.34-3.44 (m, 1H, CHCH₃), 3.89-3.93 (m, 1H, H5), 3.98 (s, 5H,

Cp⁰), 4.31-4.34 (m, 1H, H4), 4.52-4.56 (m, 1H, H3), 7.19-7.26

(m, 5H, Ph^B-ortho þ Ph^B-meta þ Ph^B-para), 7.34-7.40 (m, 3H,

Ph^A-meta þ Ph^A-para), 7.54-7.63 (m, 2H, Ph^A-ortho). ¹³C{¹H}

NMR (100.6 MHz, CDCl₃): δ 23.2 (dd, J = 6.1 Hz, J = 2.9 Hz,

CHCH₃), 29.9 (dd, J = 31.4 Hz, J = 9.6 Hz, CHCH₃), 30.7 (d,

J = 13.5 Hz, C^A(CH₃)₃), 31.9 (d, J = 14.9 Hz, C^B(CH₃)₃),

33.0 (d, J = 32.2 Hz, C^A/B(CH₃)₃), 33.7 (d, J = 23.9 Hz,

C^A/B(CH₃)₃), 69.4 (s, C4), 69.9 (d, J = 2.9 Hz, Cp⁰), 70.5 (dd,

J = 4.3 Hz, J = 2.5 Hz, C5), 71.1 (dd, J = 9.4 Hz, J = 4.1 Hz,

C3), 73.7 (t, J = 8.0 Hz, C1), 103.9 (dd, J = 22.9 Hz, J = 26.2

Hz, C2), 127.5 (s, Ph^B-para), 127.8 (d, J = 12.2 Hz, Ph^A/B-meta),

127.9 (d, J = 12.2 Hz, Ph^A/B-meta), 129.0 (s, Ph^A-para), 132.5

(d, J = 17.6 Hz, Ph^B-ortho), 135.4 (d, J = 22.2 Hz, Ph^A-ortho),

138.7 (d, J = 7.9 Hz, Ph^A-ipso), 141.1 (d, J = 8.8 Hz, Ph^B-ipso).

³¹P NMR (162 MHz, CDCl₃): δ -24.5 (s, PPh₂), 42.4 (s,

P-t-Bu₂). HR-MS (ESI in MeOH/MeCN): m/z = [M þ H^þ]^þ

calcd 543.2034 for C₃₂H₄₁FeP₂, found 543.2026. [R]²⁰_λ(nm): þ399.5

(589), þ430.6 (578), þ563.4 (546) (c 0.814, CHCl₃).

connected to C6-P. Anal. Calcd for C₄₄H₄₂Cl₂FeP₂PdSi

3

0.25CHCl₃: C, 57.62; H, 4.62. Found: C, 58.01; H, 4.50. ESI-

MS (MeOH/MeCN): m/z = 857.2 [M - Cl^-]^þ. [R]²⁰(nm):

λ

þ289.8 (589), þ308.6 (578), þ393.1 (546) (c 0.554, CH₂Cl₂).

Dichloro[(R,S_Fc)-1-trimethylsilyl-2-(r-bis(3,5-bistrifluoromethyl-

phenyl)phosphino-2-(diphenylphosphinophenyl)methyl)ferrocene-

P,P]palladium, [PdCl₂((R,S_Fc)-3b)]. A solution of bis(acetoni-

trile)dichloropalladium(II) (25.9 mg, 0.1000 mmol) in DMF

(2 mL) was added to a solution of (R,S_Fc)-3b (98.9 mg, 0.1000

mmol) in DMF (2 mL), and the resulting mixture was stirred at

rt overnight. Solvent was then removed under reduced pressure,

and the residue was redissolved in a minimum amount of

chloroform. Careful addition of DEE led to precipitation of a

red-brown solid, which was collected by filtration, washed with

DEE (2 ꢀ 2 mL), and dried in vacuo (106 mg, 0.0909 mmol, 91%

yield). Mp: >230 °C (dec). ¹H NMR (600 MHz, CDCl₃): δ

-0.05 (s, 9H, Si(CH₃)₃), 3.38 (s, 5H, Cp⁰), 4.09-4.12 (m, 1H,

H2), 4.53-4.57 (m, 1H, H3), 4.81 (dd, J = 18.5 Hz, J = 5.6 Hz,

1H, H6), 5.27-5.30 (m, 1H, H4), 6.86-6.93 (m, 2H, Ph^A-ortho),

7.01-7.24 (bs, 2H, Ph^C-ortho), 7.16-7.22 (m, 2H, Ph^A-meta),

7.33-7.41 (m, 2H, H9 þ Ph^A-para), 7.43-7.48 (m, 1H, H10),

7.61-7.72 (m, 3H, Ph^B-meta þ Ph^B-para), 7.72-7.77 (m, 1H,

H11), 7.78-7.83 (m, 2H, H12 þ Ph^C-para), 8.03 (bs, 1H,

Ph^D-para), 8.32-8.38 (m, 2H, Ph^B-ortho), 8.30-8.47 (bs, 2H,

Ph^D-ortho). ¹³C{¹H} NMR (150.9 MHz, CDCl₃): δ 1.1 (s,

Si(CH₃)₃), 39.1 (dd, J = 28.5 Hz, J = 8.0 Hz, C6), 69.3 (s, Cp⁰),

72.3 (dd, J = 7.4 Hz, J = 2.6 Hz, C4), 72.4 (s, C3), 73.5 (d, J =

2.3 Hz, C1), 75.2 (s, C2), 90.6 (d, J = 7.2 Hz, C5), 121.6 (dd, J =

48.1 Hz, J = 14.4 Hz, C8), 122.2 (q, J = 274.0 Hz, CF₃), 122.5

(q, J = 274.0 Hz, CF₃), 125.5 (bs, Ph^C-para), 126.3 (bs,

Ph^D-para), 126.6 (d, J = 58.6 Hz, Ph^B-ipso), 128.7 (d, J =

11.9 Hz, Ph^A-meta), 129.1 (d, J = 45.1 Hz, Ph^C/D-ipso), 129.15

(s, C10), 129.16 (d, J = 11.9 Hz, Ph^B-meta), 130.5-131.1 (m, 2 ꢀ

C-CF₃), 130.8 (d, J =30.8 Hz, Ph^C/D-ipso), 131.2(d, J = 33.2 Hz,

Ph^A-ipso), 131.3 (d, J = 3.1 Hz, Ph^A-para), 132.4 (d, J = 2.9 Hz,

Ph^B-para), 132.7 (d, J = 10.9 Hz, Ph^A-ortho), 132.9 (s, C11),

133.9-134.1 (m, Ph^D-ortho þ C12), 135.7 (d, J = 10.4 Hz,

Ph^B-ortho), 137.9 (d, J = 2.6 Hz, C9), 146.0 (dd, J = 14.4 Hz,

J = 5.5 Hz, C7), Ph^C-ortho not observed. ³¹P NMR (243 MHz,

CDCl₃): δ 18.1 (d, J = 21.1 Hz, C8-P), 33.3 (d, J = 21.1 Hz,

C6-P). Ph^Aþ Ph^Bconnected to C8-P, Ph^Cþ Ph^Dconnected to

Dichloro[(R,S_Fc)-1-trimethylsilyl-2-(r-diphenylphosphino-

2-(diphenylphosphinophenyl)methyl)ferrocene-P,P]palladium,

[PdCl₂((R,S_Fc)-3a)]. A solution of bis(acetonitrile)dichloro-

palladium(II) (25.9 mg, 0.1000 mmol) in DMF (2 mL) was

added to a solution of (R,S_Fc)-3a (71.7 mg, 0.1000 mmol) in

DMF (2 mL), and the resulting mixture was stirred at rt over-

night. The solvent was removed under reduced pressure, and the

residue was dissolved in a minimum amount of chloroform.

Careful addition of DEE led to precipitation of a yellow-brown

solid, which was collected by filtration, washed with DEE (2 ꢀ 2

mL), and dried in vacuo (74 mg, 0.0828 mmol, 83% yield). Mp:

C6-P. Anal. Calcd for C₄₈H₃₈Cl₂F₁₂FeP₂PdSi 0.25CHCl₃: C,

3

48.51; H, 3.23. Found: C, 48.55; H, 3.03. ESI-MS (MeOH/

MeCN): m/z = 1164.0 [M]^þ. [R]²⁰_λ(nm): þ211.3 (589), þ225.8

(578), þ290.3 (546) (c 0.062, CH₂Cl₂).

1

>230 °C (dec). H NMR (600 MHz, CDCl₃): δ -0.04 (s, 9H,

Si(CH₃)₃), 3.28 (s, 5H, Cp⁰), 4.00 (dd, J = 2.5 Hz, J = 1.1 Hz,

1H, H2), 4.42 (t, J = 2.5 Hz, 1H, H3), 4.79 (dd, J = 18.2 Hz, J =

6.3 Hz, 1H, H6), 5.27 (dd, J = 2.5 Hz, J = 1.1 Hz, 1H, H4),

6.70-6.75 (m, 2H, Ph^C-ortho), 6.85-6.90 (m, 2H, Ph^B-ortho),

7.01-7.05 (m, 2H, Ph^C-meta), 7.12-7.15 (m, 2H, Ph^B-meta),

7.21-7.25 (m, 1H, Ph^C-para), 7.28-7.34 (m, 3H, H9 þ H10 þ

Ph^B-para), 7.36-7.40 (m, 2H, Ph^D-meta), 7.47-7.65 (m, 1H,

Ph^D-para), 7.58-7.65 (m, 4H, H11 þ Ph^A-meta þ Ph^A-para),

7.76-7.79 (m, 1H, H12), 7.99-8.04 (m, 2H, Ph^D-ortho),

8.47-8.52 (m, 2H, Ph^A-ortho). ¹³C{¹H} NMR (150.9 MHz,

CDCl₃): δ 1.3 (s, Si(CH₃)₃), 38.6 (dd, J = 29.8 Hz, J = 8.6 Hz,

C6), 68.9 (s, Cp⁰), 71.6 (s, C3), 72.8 (dd, J = 6.6 Hz, J = 3.3 Hz,

C4), 73.9 (d, J = 2.4 Hz, C1), 74.0 (s, C2), 92.2 (d, J = 6.7 Hz,

C5), 122.0 (dd, J = 48.5 Hz, J = 14.1 Hz, C8), 126.1 (d, J = 49.4

Hz, Ph^D-ipso), 127.2 (d, J = 11.7 Hz, Ph^C-meta), 127.6 (d,

J = 56.1 Hz, Ph^C-ipso), 128.0 (d, J = 7.2 Hz, C10), 128.2 (d, J =

12.0 Hz, Ph^B-meta), 128.7 (d, J = 58.1 Hz, Ph^A-ipso), 128.8

X-ray Crystallography. X-ray data for the compounds rac-

(R,R_Fc)-2, [PdCl₂(R,S_Fc)-3b], rac-(S,R_Fc)-7, rac-(S,S_Fc)-31, and

rac-(S,S_Fc)-33 were collected on two Bruker CCD area detec-

tor diffractometers (Smart APEX and Kappa APEX-2) using

˚

graphite-monochromated Mo KR radiation (λ = 0.71073 A)

and combinations of j- and ω-scan frames. All measurements

were carried out at T = 100 K. After data integration with the

program SAINT, corrections for absorption and λ/2 effects were

applied with the program SADABS.²²The structures were solved

with the program SHELXS97 and direct methods, and refine-

ment on F²was carried out with the program SHELXL97.²³

(22) Bruker programs: SMART, version 2008; APEX2, version 2009.9-0;

SAINT, versions 6.45A and 7.68A; SADABS, version 2008/1; SHELXTL,

version 2008/4 (Bruker AXS Inc.: Madison, WI).

(23) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112–122.

6458 Organometallics, Vol. 29, No. 23, 2010

Schuecker et al.

Non-hydrogen atoms were refined anisotropically. Most H

atoms were placed in calculated positions and thereafter treated

as riding. Important crystallographic data are as follows.

rac-(R,R_Fc)-2: C₄₃H₃₈FeP₂, M_r= 672.52, orange prisms

from chloroform/hexane, 0.49 ꢀ 0.32 ꢀ 0.18 mm, monoclinic,

rac-(S,S_Fc)-31: C₂₀H₂₃BrFeOSi, M_r= 443.23, orange prisms

from heptane, 0.41 ꢀ 0.18 ꢀ 0.16 mm, monoclinic, space group

˚

P2₁/c, a = 13.042(5) A, b = 12.521(5) A, c = 12.697(5) A, β =

118.354(5)°, V = 1863.5(12) A , Z = 4, μ = 3.022 mm^-1, d_x=

3

˚

1.580 g cm^-3, T = 100 K. 12 717 reflections collected (θ_max

=

˚

space group P2₁/c, a = 10.1443(2) A, b = 19.3345(4) A, c =

28.4°) and merged to 4614 independent data (R_int= 0.041); final

R indices (all data): R₁=0.0482, wR₂= 0.0699, 221 param-

eters. Hydroxy hydrogen atom fully refined.

3

˚

17.0532(3) A, β = 91.735(1)°, V = 3343.20(11) A , Z = 4, μ =

0.578 mm^-1, d_x= 1.336 g cm^-3, T = 100 K; 49 959 reflections

collected (θ_max= 30.0°) and merged to 9740 independent data

(R_int= 0.023); final R indices (all data): R₁= 0.0371, wR₂=

0.0875, 416 parameters.

rac-(S,S_Fc)-33: C₂₉H₂₇BBrFeP, M_r= 553.05, orange crystals

from chloroform/hexane, 0.48 ꢀ 0.24 ꢀ 0.13 mm, monoclinic,

˚

space group P2₁/c, a = 20.7001(5) A, b = 7.2546(2) A, c =

˚

3

˚

[PdCl₂((R,S_Fc)-3b)] as the chloroform solvate [PdCl₂((R,S_Fc)-

3b)] CHCl₃: C₄₉H₃₉Cl₅F₁₂FeP₂PdSi, M_r= 1285.33, orange

17.2963(5) A, β = 107.297(1)°, V = 2479.94(12) A , Z = 4, μ=

2.300 mm^-1, d_x=1.481 g cm^-3, T=100 K; 23 006 reflections

collected (θ_max= 30.0°) and merged to 7212 independent data

(R_int= 0.026); final R indices (all data): R₁= 0.0368, wR₂=

0.0733, 298 parameters.

3

plates from chloroform/hexane, 0.37 ꢀ 0.24 ꢀ 0.08 mm, mono-

˚

clinic, space group P2₁, a = 10.7270(16) A, b = 13.3092(19) A,

˚

3

˚

c = 18.395(3) A, β = 95.214(2)°, V = 2615.3(7) A , Z = 2, μ =

1.038 mm^-1, d_x= 1.632 g cm^-3, T = 100 K; 44 338 reflections

collected (θ_max= 30.0°) and merged to 15 197 independent data

(R_int= 0.043); final R indices (all data): R₁= 0.0607, wR₂=

0.1138, 644 parameters. Flack absolute structure parameter =

-0.022(15). CHCl₃solvent molecule partly vacant, refined

population 68.7(5)%.

Acknowledgment. This work was kindly supported by

SOLVIAS AG. The authors thank Manuela Gross for

some preparative help.

rac-(S,R_Fc)-7: C₃₂H₃₁FeOP, M_r= 518.39, orange plates from

chloroform/hexane, 0.32 ꢀ 0.30 ꢀ 0.13 mm, monoclinic, space

Supporting Information Available: Standard ORTEP plots

and standard geometric parameters for crystal structures of

compounds rac-(R,R_Fc)-2, [PdCl₂((R,S_Fc)-3b)] CHCl₃, rac-

(S,R_Fc)-7, rac-(S,S_Fc)-31, and rac-(S,S_Fc)-33 as well as complete

crystallographic data and technical details in CIF format. This

material is available free of charge via the Internet at http://

pubs.acs.org.

˚

group P2₁/n, a=8.6582(11) A, b=25.464(3) A, c=11.6474(15) A,

3

β = 93.500(2)°, V = 2563.2(6) A , Z = 4, μ = 0.674 mm^-1, d_x=

˚

1.343 g cm^-3, T= 100 K. 37 286 reflections collected (θ_max=30.0°)

and merged to 7470 independent data (R_int= 0.031); final R indices

(all data): R₁= 0.0403, wR₂= 0.0809, 318 parameters.

Article Doi

Synthesis of ferrocenyl diphosphine ligands: Substitution of α-methoxy or α-dimethylamino groups by phosphines. Retention versus inversion: A stereochemical study

DOI: 10.1021/om100843u

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Article abstract of DOI:10.1021/om100843u

Full text of DOI:10.1021/om100843u

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