Synthesis of achiral, but unsymmetric, seven-membered rhodium(I)-chelates for hydrogenation in the chiral environment of alkyl polyglucoside micelles

Article abstract of DOI:10.1016/S0022-328X(00)00845-7

Chiral rhodium(I) chelates containing a seven-membered ring are well-known active catalysts for the asymmetric hydrogenation of amino acid precursors. A high conformational flexibility allows their enantioselectivity to be strongly influenced by modifiers. Now we show the nature of the counter-ions to have a large influence in apolar solvents. In addition, the presence of micelle forming alkyl polyglycosides as amphiphiles causes a remarkable increase in the enantiomeric excess (%ee). However, on achiral catalysts this enantioselectivity inducing effect scarcely exceeds the standard deviation for the gas chromatographic determination of the enantiomeric ratio. This is also true for the application of unsymmetric P,P′-ligands such as 3-phosphinopropyl-phosphinites or butane-1,4-diyl-bis(phosphines) carrying different P′-aryl groups, for which synthetic routes are given.

Full text of DOI:10.1016/S0022-328X(00)00845-7

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 621 (2001) 120–129
Synthesis of achiral, but unsymmetric, seven-membered
rhodium(I)-chelates for hydrogenation in the chiral environment of
alkyl polyglucoside micelles
V. Fehring a, R. Kadyrov a, M. Ludwig a, J. Holz a, K. Haage b, R. Selke a,*
a Institut fu¨r Organische Katalyseforschung an der Uni6ersita¨t Rostock, e.V., Buchbinderstr. 5-6, D18055 Rostock, Germany
b Max-Planck-Institut fu¨r Kolloid- und Grenzfla¨chenforschung, Abteilung Grenzfla¨chen, Am Mu¨hlenberg 2, Golm, D-14424 Potsdam, Germany
Received 1 August 2000; received in revised form 14 September 2000; accepted 21 September 2000
Dedicated to Professor H. Brunner on the occasion of his 65th birthday
Abstract
Chiral rhodium(I) chelates containing a seven-membered ring are well-known active catalysts for the asymmetric hydrogenation
of amino acid precursors. A high conformational flexibility allows their enantioselectivity to be strongly influenced by modifiers.
Now we show the nature of the counter-ions to have a large influence in apolar solvents. In addition, the presence of micelle
forming alkyl polyglycosides as amphiphiles causes a remarkable increase in the enantiomeric excess (%ee). However, on achiral
catalysts this enantioselectivity inducing effect scarcely exceeds the standard deviation for the gas chromatographic determination
of the enantiomeric ratio. This is also true for the application of unsymmetric P,P%-ligands such as 3-phosphinopropyl-phos-
phinites or butane-1,4-diyl-bis(phosphines) carrying different P%-aryl groups, for which synthetic routes are given. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Alkyl polyglycosides; Asymmetric hydrogenation; Counter-ions; Micelles; Rhodium(I) chelates; Unsymmetric bisphosphines
1. Introduction
phosphine), forming a six-membered chelate ring,
proved to be unsuccessful in this respect.
Following the ideas of Oehme et al. [1] we found by
the addition of amphiphiles an impressive increase in
the enantioselectivity in water for a large number of
chiral rhodium(I) chelates as asymmetric hydrogenation
catalysts [2]. Recent investigations of Oehme et al. to
try to realize asymmetric hydrogenations using achiral
catalysts, relying only on the enantiodifferentiating ac-
tion of chiral amphiphiles, led to very small effects [3].
The seven-membered rhodium(I) chelate of butane-1,4-
diyl-bis(diphenylphosphines), [Rh(BDPP)(COD)]BF4,
gave reliable but unsatisfactory enantioselectivities of
up to 8%ee when amphiphiles derived from enantiopure
carbohydrates or amino acids were applied. In contrast
the rhodium complex of propane-1,3-diyl-bis(diphenyl-
The background for the preparation of unsymmetric
ligands with two coordinatively distinguishable phos-
phorus atoms, which are here presented, was to attempt
to enable its rhodium complexes to a higher stereodif-
ferentiation in the chiral environment formed by mi-
celles of alkyl polyglucosides. Considering the strong
electronic effects of P-aryl substituents on the enan-
tioselectivity of carbohydrate bisphosphinite catalysts
found by RajanBabu et al. [4] we supposed that it
might be important to differentiate the electronic state
of both phosphorus atoms in the newly synthesized
ligands to enable the chiral medium to take effect.
Seven-membered chelates were chosen because we
had already shown that the enantioselectivity of such
rhodium(I) chelates, caused by their high conformative
flexibility, is strongly susceptible to the influences of
solvents, substrates or additives [2,5]. In special cases
this covers nearly the whole range of enantioselectivity
from about 90%ee (S) to nearly 90%ee (R) for one and
* Corresponding author. Tel.: +49-381-4669335; fax: +49-381-
4669324.
E-mail address: ruediger.selke@ifok.um-rostock.de (R. Selke).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00845-7

V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
121
the same catalyst species [6]. Furthermore we state now
2. Results and discussion
an important unpublished influence of counter ions (see
Fig. 1) on the enantioselectivity of the chiral [Rh(Ph-b-
glup-OH)]+ (1). This catalyst has already found indus-
2.1. Influence of counter-ions on the enantioselecti6ity
of [Rh(Ph-i-glup-OH)]+ (1)
trial application [7] in
Chemie Zwickau from 1986 to 1990.
L-DOPA production by ISIS
The pre-catalysts for [Rh(Ph-b-glup-OH)]+ (1),
which contain cis,cis-cycloocta-1,5-diene (COD) for
stabilisation were prepared as earlier reported [8]. The
complex with the dodecylsulfate (DS−) counter-ion was
prepared according to an analogous method to that
given in reference [2c]. In protic solvents, such as
alcohols, the enantioselectivity is not controlled by the
counter-ion because the catalysts act in the dissociated
form, independently of the anion. However, in aprotic
solvents we observed a considerable influence of the
anion on the enantiomeric excess in the hydrogenation
of methyl (Z)-2-acetamidocinnamate (see Fig. 1). A
pronounced anion effect results in apolar solvents like
aromatic hydrocarbons in which the catalyst is nor-
mally present as an ion pair [9]. Particularly high
enantioselectivities of about 99%ee are found in toluene
using the dodecyl sulfate anion. This prompts to be
wary with the statement that micelle formation causes
increased enantioselectivity under the action of am-
phiphiles [2a]. The insignificance of formation of re-
versed micelles for the increase of enantioselectivity was
proven for apolar solvents [10]. In water, however, a
relationship between the amphiphile aggregation and its
effect on the enantioselectivity is plausible. We found
for instance a remarkable parallel between the micelle
However, the effect of chiral amphiphiles such as
alkyl saccharides on the enantioselectivity of achiral
catalysts was unsatisfactory, even using the new unsym-
metric ligands for rhodium(I) and despite the large
influence such amphiphiles have on the enantioselectiv-
ity of the chiral [Rh(HO-diop)]+ (2) (see Table 1).
Fig. 1. Influence of anions on the enantioselectivity of [Rh(Ph-b-glup-
OH)]+ (1) in the hydrogenation of methyl (Z)-2-acetamidocinnamate:
dependence of the applied solvents (DS− equals the dodecylsulfate
anion). Conditions: 1.0 mmol substrate, 0.01 mmol [1·(COD)]anion,
15 ml of solvent, 25°C, 0.1 MPa.
Table 1
Influence of alkyl polyglycosides on the enantioselectivity in asymmetric hydrogenations in water with catalyst 2 [Rh(Diop-OH)]+ a
a Conditions: 0.01 mmol [2·(COD)]BF4, 15 ml of water, 25°C, 0.1 MPa; Qa/b represents the relati6e enantioselecti6ity [2b], the quotient of the
ratio of product enantiomers era (in the presence of amphiphile a) and the enantiomeric ratio of the blank experiment erb:Qa/b=era/erb.

122
V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
Table 2
Hydrogenation of 2-N-acetamidocinnamic acid (AH), its methyl ester (AMe) and methyl 2-N-acetamidoacrylate (aMe); influence of C12/16-alkyl
polyglycoside (+a) a
a Conditions: 1 mmol substrate, 0.01 mmol pre-catalyst, 15 ml of solvent, 0.1 mmol amphiphile a, C12/16-alkyl polyglycoside (Henkel KGaA),
25°C, 0.1 MPa (if not otherwise noted). * In one preliminary experiment we received a much higher value of 23%ee (S); this could not be
reproduced. aMe=methyl 2-acetamido-acrylate.
NMR experiments underline the importance of micelle
formation in such cases [11].
2.2. Enhancement of the enantioselecti6ity of [Rh((R,R)-
HO-diop)]+ (2) by alkyl polyglucosides
Scheme 1.
With regard to the former success in the application
of alkyl glycosides [3a] and their easy accessibility as
industrial products, we chose commercially available
alkyl polyglucosides [12] as test examples for chiral
amphiphiles. We applied [Rh((R,R)-HO-diop)]+ (2) be-
cause of the particularly high susceptibility of its enan-
tioselectivity to the presence of amphiphiles [2c]. We
found a respectable increase in the enantioselectivity in
the hydrogenation of methyl (Z)-2-acetamidocinnamate
(AMe) and particularly its analogous acid (AH) in
water (see Table 1). The distinct drop in the reaction
rate in the presence of the alkyl glycosides for the
hydrogenation of AMe is remarkable. This is in strong
contrast to our experience with numerous amphiphiles,
which without exception, and independent of the kind
of substrate, led to a decrease of the reaction time in
micellar dispersion. It seems possible, that the main
quantity of the catalyst and the main amount of the
substrate are located in different phases: the very polar
Scheme 2.
catalyst predominantly in water, the poorly water solu-
ble AMe mainly aggregated in the micelles formed by
destroying action of added methanol and its decreasing
influence on the selectivity enhancement by sodium
dodecylsulfate [2b]. New investigations using PGSE-
the polyglucosides. The less soluble AH should be even
more concentrated in the micellar phase. This and the
higher reactivity of AH compared with AMe, which is

V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
123
well-known also by application of such catalysts in
homogeneous solution, may compensate the assumed
low concentration of the catalyst in the polyglucoside
aggregates. Thus for AH the main part of the hydro-
genation may occur within the supramolecular struc-
tures and explains at the same time the sixfold increase
of the relati6e enantioselecti6ity (84.9%ee corresponds to
The synthesis of the asymmetric phosphino phos-
phinites 8, 13, and 15 was accomplished using the
functionalised propane-1,3-diol 5 as the main building
block according to Scheme 2. This was itself synthe-
sised by the reaction of one hydroxy group of propane-
1,3-diol with 3,4-dihydro-2H-pyran followed by
protecting the second hydroxy group using tosyl chlo-
ride [15]. This unsymmetric protection permitted the
regioselective synthesis of the phosphines 7 and 12 by
the substitution of the tosyl groups by lithium phos-
phides and removal of the tetrahydro-2H-pyran pro-
tecting group. In the synthesis of phosphine 12
chloro - bis[3,5 - bis(trifluoromethyl)phenyl] - phosphine
(10a) could not be directly converted to the correspond-
ing lithium phosphide by the reaction with metallic
lithium due to the electronic withdrawing effect of the
trifluoromethyl groups. Therefore the chloro-phosphine
10a was reduced to bis[3,5-bis(trifluoromethyl)phenyl]-
phosphine (11a) by the reaction with lithium aluminium
hydride (see Scheme 3) and subsequently converted to
the corresponding lithium phosphide by butyl lithium.
The final synthesis of the phosphinite substructures
within the ligands 8, 13 and 15 occurred by the reaction
of the unprotected ligands 7 and 12 with pyridine and
chlorodiphenylphosphine or compound 10a, respec-
tively. Due to the relative instability of the free ligands
8, 13 and 15 no further purification steps were at-
tempted. Attempts to recrystallize these ligands led to
more contaminated products.
The ligands 3, 8, 13 and 15 were dissolved in tetrahy-
drofuran and treated with Rh(COD)acac followed by
the dropwise addition of tetrafluoroboric acid [8]. The
resulting rhodium complexes could then be precipitated
by diethyl ether, giving brownish muddy solids. After
removal of the solvent the residues were washed with
diethyl ether several times. The rhodium chelates 9, 14
and 16 started to crystallize during these wash proce-
dures and this could be encouraged by scratching with
a glass stick. Chelate 4 was not able to be obtained as
a pure solid product just by washing with diethyl ether.
After several wash steps the residue was dissolved in
dichloromethane and filtered. THF was then carefully
added to the clear solution and the chelate started to
crystallize. All chelates were able to be recrystallized.
During hydrogenation experiments the catalysts con-
taining ligands with one phosphinite group showed an
unexpectedly rapid inactivation in solvents containing
water (see Table 2). We have never observed this with
the analogous chelates of carbohydrate-bisphosphinites.
The assumption that hydrolysis of the less hindered
P-O bond in the new complexes could be the reason for
this inactivation prompted us to prepare the butane-
1,4-diyl-bis(phosphine) ligands 20b, 20c and 20d for
similar unsymmetric seven-membered chelates 21b, 21c
and 21d without a P-O bond according to Scheme 3.
For this purpose 4-hydroxybutyl-diphenylphosphine 17
Qa/b=6.0; see Table 1).
The extreme increase of the relative enantioselectivity
in hydrogenation of AH in the presence of the C12/16-al-
kyl polyglycoside has not yet been achieved for such
substrate acids using other amphiphiles. Even with
sodium dodecylsulfate (SDS), the prototype of an enan-
tioselectivity increasing amphiphile, Qa/b did not gener-
ally reach 4.5 [2a], but remained in the case of catalyst
2 at 3.1. It seemed possible that the high increase in
selectivity could be caused by a double stereo differenti-
ation described by Masamune [13] corresponding to the
chiral amphiphile forming a matching pair with the
catalyst. In such a case one would expect a mismatch-
ing effect with lower selectivity if the enantiomer cata-
lyst [Rh((S,S)-HO-diop)]+ was applied. However, the
effect has proved to be only very small (83.1%ee S-
product, Qa/b=5.3).
2.3. Synthesis of achiral ligands and their chelates
Among the achiral rhodium(I) chelates, which were
of interest for us, are some symmetric complexes for the
comparison with the unsymmetric, but nevertheless
achiral chelates (see Table 2). Particularly the synthesis
of ethylene-bis(diphenylphosphinite) (Scheme 1) must
be conducted carefully. This bisphosphinite 3 is known
for its instability, caused by Michaelis Arbuzov like
rearrangements leading to phosphinoxides [14]. Due to
this reactivity the synthesis of ligand 3 is accomplished
by adding chlorodiphenyl phosphine to glycol at
−15°C. The reaction mixture had to be kept at this
temperature even during work up to prevent any rear-
rangement. The resulting ligand 3 was therefore used
without any further purification for the preparation of
rhodium chelate 4.
Scheme 3.

124
V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
[16] in the borane protected form 18 was transferred to
the diphosphines 20b, 20c and 20d. The nucleophilic
substitution was done by lithium phosphides obtained
from the phosphines 11b, 11c, and the commercially
available dicyclohexylphosphine. The purification was
accomplished by a borane protection/deprotection pro-
cess. Finally the rhodium chelates were prepared from
the phosphines in the usual way [8].
the determination of the enantioselectivity are thinkable
(selective association of one enantiomer). Indeed the
reproducibility of the experiments was low with an error
in the order of 915%ee. This leds to doubts in any
enantioselectivity enhancement.
To increase the complex stability we introduced the
rhodium(I)-chelates 21b, 21c and 21d containing unsym-
metric butane-1,4-diyl-bis(phosphine) ligands. Indeed
they showed no inactivation even in pure water and the
hydrogenation could be completed in all cases within
two hours. However, the enantioselectivity remained
below 4%ee (R)-N-acetylphenylalanine (see Table 3).
2.4. Results of hydrogenation experiments
The results of the hydrogenation experiments with the
rhodium(I) chelates of unsymmetric P,P%-ligands when
compared to some symmetric catalysts were disappoint-
ing. The experimental error in the gas chromatographic
estimation of the enantiomeric excess is particularly high
in the racemate region and may reach 92.5%ee as
known from earlier error evaluation and can be deduced
from the experiments with AMe and methyl 2-acetami-
doacrylate (aMe) without any chiral additives (see Table
2). For the measurements modified with the chiral
C12/16-alkyl polyglycoside we chose the acid substrate
AH because it displayed the highest relative enantioselec-
tivity with catalyst 2 in the presence of this amphiphile
(see Table 1). However, applying the achiral catalysts the
enantioselectivity was lower than 2.5%ee and besides
that the conversion time strongly increased. This may be
caused by a hydrolysis of the P–O bond of the phos-
phinites even in the chelates by the action of water. We
tried to improve the situation by applying 10% methanol
to the solvent to increase the solubility of the substrate
and the complexes, and chose 10 MPa hydrogen pressure
to increase the reaction rate. The result was not much
better, with the conversion not exceeding 20% in 20 h,
which hindered a reliable %ee estimation. Since in these
cases the amount of chiral amphiphile lay in the order
of the hydrogenation product, substantial mistakes in
3. Experimental
The alkyl polyglucosides [C8/10-alkyl polyglycosid (GZ
1,5) APG 220 UP and C12/16-alkyl polyglycosid (GZ 1,4)
APG 600 UP] of the Henkel KGaA were freeze-dried at
room temperature (r.t.) and extracted with n-hexane.
The hydrogenations and gas chromatography of the
products were conducted as described in Ref. [2a]. Acidic
hydrogenation products were esterified before GC anal-
ysis. The gas chromatographic estimation of the enan-
tioselectivity was controlled by HPLC. NMR spectra
1
were recorded on a Bruker ARX 400; H-NMR (400
MHz), 13C-NMR (100 MHz), 31P-NMR (162 MHz).
3.1. Preparation of compounds
3.1.1. cis,cis-Cycloocta-1,5-diene[phenyl 2,3-O-
bis(diphenylphosphino)-i-D-glucopyranoside]rhodium(I)
dodecylsulfate ([1(COD)]DS)
cis,cis-Cycloocta-1,5-diene[phenyl2,3-O-bis(diphenyl-
phosphino)-b-
D-glucopyranoside]rhodium(I)tetrafluoro-
borate [8] ([1(COD)]BF4, 920 mg, 1 mmol) and sodium
Table 3
No influence of the C12/16-alkyl polyglycoside a ( Henkel KGaA) on the selectivity in the hydrogenation with achiral rhodium(I)-chelates of
unsymmetric 1,4-diphosphino-butane ligands a
a Standard conditions as in Table 2.

V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
125
dodecylsulfate (287 mg, 1 mmol) were dissolved in 30
ml of methanol at 50°C while stirring. To the warm
solution 150 ml of water were added slowly and the
stirring continued over night. The yellow orange com-
plex that separated from the nearly colourless solution
on the flask walls, was washed twice with 10 ml water
and dried under reduced pressure at 30°C. Yield: 0.781
g (71%); C56H71O10P7RhS (1101.04) Calc.: C, 61.0; H,
6.5; P, 5.6; Rh, 9.4; S, 2.9; Anal. Found: C, 60.2; H,
6.1; P, 6.1; Rh, 9.8; S, 3.1%.
diethyl ether (100 ml) from the aqueous phase, the
organic phase was washed with brine several times,
dried (sodium sulfate) and the solvent was removed
under reduced pressure. The resulting residue was dis-
solved in abs. pyridine (5 ml) and dichloromethane (20
ml), the solution was treated with toluene sulfonyl
chloride (3.0 g, in portions) and was stirred at r.t. for
further 16 h. Then the reaction mixture was diluted
with dichloromethane (40 ml), washed with hydrochlo-
ric acid (5%), aqueous bicarbonate solution and brine.
After removing of the solvent under reduced pressure
the final product 5 was purified by column chromatog-
raphy giving a colourless oil; Rf:0.2 (hexane/ethyl
acetate 5:1, v/v).
3.1.2. [Rh(COD)(Ph2POCH2CH2OPPh2]BF4 (4)
A solution of abs. ethylene glycol (0.1 ml, 1.77
mmol), abs. pyridine (0.32 ml, 4.0 mmol) and abs.
tetrahydrofuran (5 ml) was cooled under argon to
−15°C and chlorodiphenyl phosphine (0.66 ml, 3.6
mmol) was added dropwise to the stirred solution.
After stirring for 1 h at −15°C the precipitated pyri-
dinium salt was removed by tube filtration and the
filtrate was transferred to a precooled Schlenk vessel
(−15°C) and the solvents were removed under reduced
pressure. Simultaneously the temperature of the reac-
tion mixture was kept as low as possible. The residue
was dissolved in abs. tetrahydrofuran (3 ml) and treated
with Rh(COD)acac (0.554 g, 1.77 mmol). This reaction
mixture was allowed to warm up to r.t. and was then
treated dropwise with tetrafluoroboric acid (0.195 ml,
50%). After stirring for 10 min diethyl ether (10 ml) was
added and the product started to precipitate as a
brownish muddy solid. The solvents were removed by
tube filtration and the precipitate was washed several
times with diethyl ether (2×5 ml). The solid product
was dissolved in dichloromethane (5 ml, acid free) and
the solution was filtered. THF was added to the surface
of the clear solution and and by cooling of the mixture
the product started to precipitate. Yield: 0.598 g
3.1.4. Ph2P(CH2)3O–THP (6)
A stirred mixture of lithium (0.5 g) and tetrahydro-
furan (25 ml) was treated dropwise with chlorodiphenyl
phosphine (4.4 ml) at r.t. The first ten drops were added
quite fast whereas the rest of the phosphine was not
added before the solution started to get a red colour.
The red lithium diphenylphosphide solution was
added dropwise to a stirred and ice cooled solution of
tosylate 5 (3.0 g, 9.5 mmol) in abs. tetrahydrofuran (25
ml) until the red colour of the reaction mixture re-
mained. The solution was then allowed to warm up to
r.t. and more lithium diphenylphosphide solution was
added until the red colour of the reaction mixture
remained even at r.t. The solvent was then removed
under reduced pressure and the residue was dissolved in
dichloromethane (40 ml) and water (25 ml). After 16 h
the organic phase was removed, dried (sodium sulfate)
and the solvent was evaporated under reduced pressure.
The final product was purified by column chromatogra-
phy. Yield: 3.087 g (98%) 6; Rf:0.5 (hexane/ethyl
acetate 8:1, v/v); 13C-NMR (CDCl3): l=137.8–127.4
1
(45.9%); H-NMR (acetone-d6): l=7.6–7.46 (m, 10H,
(2 Ph), 99.2 (O–C6 H–O), 68.4 (OC6 H2), 62.8 (OC6 H2),
2 Ph), 4.54–4.5 (m, 2H, H
2H, 2 CH2), 2.52–2.35 (m, 4H, 4 HCꢀCH-CH2
NMR (acetone-d6): l=132.3, 132.0, 131.9, 129.2 (Ph),
105.1 (HCꢀCH–CH2), 68.8 (O–CH2), 30.2 (HCꢀCH–
H2); 31P-NMR (acetone-d6): l=125.3 (d, J:194.4).
6
CꢀCH
6
–CH2), 2.96–2.82 (br,
31.2, 26.7, 25.9, 25.0, 20.1 (5 CH2); 31P-NMR (CDCl3):
l= −15.6 (s); C20H25O2P (328.39) Calc.: C, 73.2; H,
7.7; Anal. Found: C, 73.2; H, 7.6%.
6
6
); 13C-
6
C6
3.1.5. Ph2P(CH2)3OH (7)
A solution of the diphenylphosphine 6 (1.91 g, 5.8
mmol) in abs. ethanol (20 ml) was treated with pyri-
dinium p-toluene sulfonate (a few mg) and was slowly
warmed up to 50°C. The reaction progress was fol-
lowed by TLC. At the end of the reaction the solvent
was removed under reduced pressure and the product
was purified by column chromatography.
3.1.3. TsO(CH2)3O–THP (5)
3,4-Dihydro-2H-pyran (4.5 g, 52 mmol) was added
to a cooled solution of propane-1,3-diol (4) (10 g, 132
mmol) and toluene sulfonic acid (0.13 g) in abs. tetra-
hydrofuran (250 ml) in a dropwise manner. After
stirring for 1 h at 0°C the reaction mixture was allowed
to warm up to r.t. and was stirred for an additional
hour before adding triethylamine (1.5 ml). The solvents
were removed under reduced pressure and the residue
was dissolved in a mixture of water (20 ml) and
methanol (100 ml). After washing several times with
hexane, the methanol was removed under reduced pres-
sure. The remaining product was then extracted with
Yield: 1.11 g (78%) 7; Rf:(hexane/ethyl acetate 4:1,
1
v/v); H-NMR (CDCl3): l=7.76–7.28 (m, 10H, 2 Ph),
3.69 (2H, PCH2), 2.14–2.1 (m, 2H, CH2OH), 1.74–1.64
(m, 2H, CH2); 13C-NMR (CDCl3): l=139.0–128.9 (2
Ph), 63.8, 29.5, 24.7 (3 CH2); 31P-NMR (CDCl3): l=
−15.7 (s); C15H17OP (244.27) Calc.: C, 73.8; H, 7.0;
Anal. Found: C, 72.8; H, 6.9%.

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V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
3.1.6. Ph2P(CH2)3OPPh2 (8)
3.1.10. (MeOC6H4)2P(O)H (10c)
Chloro-diphenylphosphine (0.99 ml, 5.38 mmol) was
This compound was prepared from (EtO)2POH and
4-MeOC6H4MgBr (obtained from 4-bromoanisole) by
the method of Lorenz and Schrader [19]. M.p.=124–
added to stirred and ice cooled solution of
a
diphenylphosphine 7 (1.19 g, 4.89 mmol) and abs.
pyridine (0.415 ml) in abs. tetrahydrofuran (15 ml). The
reaction mixture was allowed to warm up to r.t. within
18 h and the precipitated pyridinium hydrochloride was
removed by filtration. The salt was washed with abs.
tetrahydrofuran (5 ml) and the combined filtrates were
dried under reduced pressure.
1
125°C; H-NMR (CDCl3): 3.71 (s, 6H), 6.92 (d, J=7,
4H), 7.55 (dd, J=14.2, J=7, 4H), 7.94 (d, J=480,
1H); 13C-NMR (CDCl3): 55.8, 114.7 (d, J=20), 123.5
(d, J=110), 133.0 (d, J=20), 163.2 (d, J=10); 31P-
NMR (CDCl3): 20.9.
Yield: 1.74 g (83%) 8; 13C-NMR (CDCl3): l=142.6–
128.7 (4 Ph), 71.2, (OCH2), 28.4 (CH2), 24.8 (CH2);
31P-NMR (CDCl3): l=113.2 (OP(Ph)2), −15.9
(H2CꢁP(Ph)2).
3.1.11. [3,5-(CF3)2C6H3]2PH (11a)
Following a modified procedure of Casey et al. [20] a
solution of 10a (7.70 g, 16 mmol) in ether (50 ml) was
added slowly to a suspension of LiAlH4 (0.59 g, 16
mmol) in ether (150 ml). After refluxing for 2 h, 0.6 ml
of H2O was added and the resulting slurry filtered of.
The filtrate was concentrated in vacuo to give 11a as
white solid. Yield: 6.78 g (95%); m.p.=67–68 °C (Lit.
69–71°C [20]); 1H-NMR (CDCl3): 5.65 (d, J=230,
1H), 7.85 (m, 6H); 13C-NMR (CDCl3): 123.1 (q, J=
270), 123.8 (dd, J=4, J=3), 133.0 (qd, J=34, J=6),
134.1 (d, J=18), 136.6 (d, J=16); 31P-NMR (CDCl3):
−40.1.
3.1.7. [Rh(COD){Ph2P(CH2)3OPPh2}]BF4 (9)
A stirred solution of propane 8 (0.8 g, 1.87 mmol)
and Rh(COD)acac (0.579 g, 1.8 mmol) in abs. tetrahy-
drofuran (20 ml) was treated at r.t. with aqueous
tetrafluoro-boric acid (0.233 ml, 50%). After stirring for
20 minutes the reaction mixture was diluted with abs.
diethyl ether (20 ml) and the final product started to
precipitate as a brownish muddy solid. The solvents
were removed by tube filtration and the precipitate was
washed several times with diethyl ether (3×10 ml). The
solid product was dried under reduced pressure and
was recrystallized from chloroform/hexane. Yield: 1.11
g (82%) 9, red solid; 31P-NMR (CDCl3): l=134.5 (dd,
J:32.4, J:162, OP(Ph)2), 9.45 (dd, J:40.5,
J:137.7, H2C–P(Ph)2).
3.1.12. (3,5-Me2C6H3)2PH (11b)
Following the procedure similar to that used for
dibutylphosphine [21] a solution of 10b ( 40.5 g, 0.16
mol) in ether (50 ml) was added slowly to a suspension
of LiAlH4 (6 g, 0.16 mmol) in ether (500 ml). The
reaction mixture was refluxed for 2 h and hydrolyzed
with 10% H2SO4. The organic layer was separated and
the aqeous layer was extracted with ether and toluene.
The combined organic layers were washed with water,
dried over Na2SO4 and evaporated to give a brownish
oil. High vacuum fractional distillation gave 11b as a
colourless oil. Yield: 24.1 g (64%); b.p.=105–106/0.02
(Lit. 120–145/0.01 [22]); 1H-NMR (CDCl3): 2.26 (s,
6H), 5.11 (d, J=230, 1H), 6.92 (s, 2H), 7.11 (d, J=8.3,
4H); 13C-NMR (CDCl3): 21.7, 130.2, 131.7 (d, J=18),
134.5 (d, J=11), 138.0 (d, J=7); 31P-NMR (CDCl3):
−39.1.
3.1.8. [3,5-(CF3)2C6H3]2PCl (10a)
Following a modified procedure of Casalnuovo et al.
[17] a solution of (NEt2)PCl2 (13.3 g, 77 mmol) in ether
(50 ml) was added slowly to a solution of 3,5-
(CF3)2C6H3MgBr [prepared from 49.8 g (0.17 mol)
3,5-bis(trifluoromethyl)-brombenzene and 4.5 g (0.18
mol) Mg] in ether (200 ml) at −50°C. The reaction
mixture was warmed to r.t. and stirred 1 h, then cooled
to 0°C and dry HCl was passed through the solution
for 30 min. After removal of excess HCl in vacuo the
resulting solids were filtered under argon atmosphere
and the filtrate was concentrated to give an oil. High
vacuum distillation gave 10a as colourless oil. Yield:
20.9 g (55%); b.p.=75–85/0.01 (Lit. 85–95/0.05 [18]);
31P-NMR (CDCl3): l=71.1.
3.1.13. (MeOC6H4)2PH (11c)
A solution of 11b (10 g, 38.1 mmol) in THF (50 ml)
was added slowly to a suspension of LiAlH4 (2 g, 52.7
mmol) at 0–5°C. The resulting suspension was stirred
over night at r.t. and 2 h under reflux. Then NaOH
(7%, 3 ml) was added, the formed white precipitate was
filtered (G4) and the solvent removed in vacuo to give
a yellow solid. Distillation in vacuo afforded the pure
product. Yield: 1.3 g (14%); b.p.=150/0.02 (Lit. 145–
3.1.9. [3,5-Me2C6H3]2POH (10b)
This compound was prepared from (EtO)2POH and
3,5-Me2C6H3MgBr (obtained from bromo-3,5-dime-
thylbenzene) by the method of Lorenz and Schrader
[19]. The product crystallized upon storage.
M.p.=115–117°C; 1H-NMR (CDCl3): 2.33 (s, 6H),
7.17 (s, 2H), 7.30 (d, J=14.2, 4H), 7.86 (d, J=540.1,
1H); 13C-NMR (CDCl3): 21.2 (d, J=10), 125.5, 128.6
(d, J=20), 131.3 (d, J=100), 134.7 (d, J=3);
31P-NMR (CDCl3): 23.3.
1
148/0.2 [23]); H-NMR (CDCl3): 3.72 (s, 6H), 6.76 (d,
J=8, 4H), 7.28 (d, J=8, 4H); 13C-NMR (CDCl3):
55.6, 114.6 (d, J=7), 126.2 (d, J=7) 135.9 (d, J=18),
160.5; 31P-NMR (CDCl3): −44.3.

V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
127
3.1.14. [3,5-(CF3)2C6H3]2P(CH2)3OH (12)
removed by filtration. The salt was washed with abs.
tetrahydrofuran (5 ml) and the combined filtrates were
dried under reduced pressure. Yield: 1.97 g (35%) 15;
31P-NMR (CDCl3): l=104.7 (OP(Ph)2), −16.1 (H2C–
P(Ph)2).
Butyl lithium (5.75 ml, 2.5 M solution in diethyl ether,
14.4 mmol) was carefully added to a stirred and cooled
(−78°C) solution of phosphine 11a (6.8 g, 14.84 mmol)
in abs. tetrahydrofuran (40 ml). The reaction mixture
was warmed up to r.t. and was stirred for 30 min. Then
the red solution obtained was carefully added to a stirred
solution of tosylate 5 (4.52 g, 14.4 mmol) in abs.
tetrahydrofuran (30 ml). After 14 days the reaction
mixture was evaporated nearly to dryness and the residue
was dissolved in dichloromethane (50 ml) and water (40
ml). After complete phase separation the organic phase
was removed, dried (sodium sulfate) and evaporated to
dryness under reduced pressure. The remaining residue
was purified by flash chromatography and the product
obtained was dissolved in methanol (50 ml). After adding
pyridinium tosylate (a few mg) to the stirred methanol
solution the reaction progress was followed by TLC. At
the end of the reaction the solvent was removed under
reduced pressure and the product was purified by column
chromatography. Yield: 1.99 g (26.8%) 12; Rf:0.31
(hexane/ethyl acetate 5:1, v/v); 31P-NMR (CDCl3): l=
−13.0.
3.1.18. [Rh(COD){Ph2P(CH2)3OP{3,5-(CF3)2-
C6H3}2}]BF4 (16)
A stirred solution of ligand 15 (1.9 g, 2.71 mmol) and
Rh(COD)acac (0.84 g, 2.71 mmol) in abs. tetrahydro-
furan (20 ml) was treated at r.t. with aqueous tetrafluoro
boric acid (0.338 ml, 50%). After stirring for 20 min the
reaction mixture was diluted with abs. diethyl ether (20
ml) and the final product started to precipitate as a
brownish muddy solid. The solvents were removed by
tube filtration and the precipitate was washed several
times with diethyl ether (3×10 ml). The solid product
was dried under reduced pressure and was recrystallized
from dichloromethane/tetrahydrofuran. Yield: 1.27 g
(47%) red solid 16; 31P-NMR (CDCl3): l=131.15 (dd,
J:32.4, J:178.2), 9.95 (dd, J:32.4, J:137.7).
3.1.19. Ph2P(BH3)-(CH2)4-OTs (18)
To a solution of Ph2P(CH2)4OH (8.5 g, 32.9 mmol)
(17) [16] in THF (30 ml) was added a solution of BH3
(35 ml, 1 M) in THF at 0°C. The solvent was evaporated
and the resulting solid was dissolved in CH2Cl2 (30 ml)
and pyridin (9 ml). After addition of TsCl (5.7 g, 30
mmol) at 0°C in portions the resulting solution was
stirred for 1 h at 0°C and stood at 5°C over night. After
stirring for 30 min at r.t. the solution was neutralized
(H2SO4, 5%) and washed with a solution of NaHCO3
and with water. The aqueous solutions were extracted
with CH2Cl2 and the combined organic fractions were
dried and evaporated to give the crude product as a clear
oil. Yield: 13 g (93%). Recrystallization from ethanol
(200 ml) afforded 18 as a white solid (5.8 g, 41%);
1H-NMR (CDCl3): 1.54 (2H, m), 1.73 (2H, m), 2.15 (2H,
m), 2.42 (3H, s), 3.99 (2H, t, J=6.3 Hz), 7.30 (2H, d,
J=7.9 Hz), 7.46 (6H, m), 7.64 (4H, m), 7.73 (2H, d,
J=8.4 Hz); 13C-NMR (CDCl3): 19.3, 21.6, 25.0 (d,
J=37.2 Hz), 29.9 (d, J=13.4), 69.5, 127.8, 128.9 (d,
J=9.5), 129.1 (d, J=53.4 Hz), 129.9, 131.3 (d, J=2.9
Hz), 132.1 (d, J=9.5), 132.8, 144.9; 31P-NMR (CDCl3):
16.2 (d, J=63.2 Hz).
3.1.15. [3,5-(CF3)2C6H3]2P(CH2)3OPPh2 (13)
Chloro-diphenylphosphine (0.71 ml, 3.85 mmol) was
added dropwise to a stirred and ice cooled solution of
phosphine 12 (1.99 g, 3.85 mmol) and pyridine (0.405 ml)
in tetrahydrofuran (15 ml). The reaction mixture was
stirred for one hour at 0°C. After stirring for further 4
h at r.t. the precipitated pyridinium hydrochloride was
removed by filtration. The salt was washed with abs.
tetrahydrofuran (5 ml) and the combined filtrates were
dried under reduced pressure. The residue was finally
dissolved in diethyl ether (15 ml), filtered and evaporated
to dryness under reduced pressure. Yield: 2.65 g (98%)
13.
3.1.16. [Rh(COD){{3,5-(CF3)2C6H3}2P(CH2)3-
OPPh2}]BF4 (14)
A stirred solution of propane 13 (2.58 g, 3.68 mmol)
and Rh(COD)acac (1.142 g) in tetrahydrofuran (10 ml)
was treated at r.t. with aqueous tetrafluoroboric acid
(0.459 ml, 50%). After stirring for 20 min the reaction
mixture was diluted with abs. diethyl ether (30 ml) and
stored at 0°C for 12 h. The solid product obtained was
filtered and recrystallized from tetrahydrofuran.
3.1.20. Ph2P(BH3)–(CH2)4–P(BH3)R2 (19b, 19c and
19d)
3.1.17. Ph2P(CH2)3OP[3,5-(CF3)2C6H3]2 (15)
A solution of BuLi (8.8 ml, 1.9 M, 16.8 mmol) in THF
was added at 0°C to HPR2 (16.8 mmol) in THF (40 ml).
The resulting deep red solution was stirred for 1 h at 0°C
and 20 min without cooling. The resulting solution of
LiPR2 was added at 0°C to Ph2P(BH3)–(CH2)4–OTs
(18) (6.5 g, 15.25 mmol) in THF (40 ml) and stirring was
continued for 1 h at 0°C and the solution allowed to
stand at 5°C over night. After addition of BH3 or
Chloro - bis[3,5 - bis(trifluoromethyl) - phenyl] - phos-
phine 10a (4.32 g, 8.78 mmol) was added dropwise to a
stirred and ice cooled solution of the diphenylphosphino
substituted propanol 7 (1.95 g, 7.98 mmol) and abs.
pyridine (0.66 ml) in abs. tetrahydrofuran (15 ml). The
reaction mixture was allowed to warm up to r.t. within
18 h and the precipitated pyridinium hydrochloride was

128
V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
BH3·SMe2 (1 M or 10 M, 36.6 mmol) the main part of
the solvent was evaporated and the residue hydrolyzed
with a solution of NH4Cl and diluted with CH2Cl2. The
organic phase was washed with brine and water, dried
and evaporated to give the crude product.
3.1.21.2. Ph2P-(CH2)4-P(4-C6H4OCH3)2 (20c). Yield:
0.55 g (53%); H-NMR (CDCl3): 1.53 (br), 1.95 (br),
1
2.01 (br), 3.77, 6.85 (m), 7.28–7.34, 7.37–7.40; 13C-
NMR (CDCl3): 28.8 (d, J=37.2), 28.1 (d, J=12.4),
28.7 (d, J=9.5), 55.6, 114.5 (d, J=6.7), 128.7 (d,
J=13.4), 128.8, 133.1 (d, J=18.1), 134.4 (d, J=20.0),
139.2 (d, J=13.4), 160.5; 31P-NMR (CDCl3): −19.2,
−15.7.
3.1.20.1.
Ph2P(BH3)–(CH2)4–P(BH3)(3,5-Me2C6H3)2
(19b). Yield (crude): 6.7 g. The crude product was
boiled with ethanol (200 ml) for extraction. The filtrate
was cooled to r.t. affording the pure product 19b.
Yield: 1.4 g (12%); 1H-NMR (CDCl3): 0.5–1.4 (6H, br),
1.58 (4H, m), 2.15 (4H, m), 2.31 (12H), 7.08 (2H), 7.21
(4H, m), 7.43 (6H, m), 7.63 (4H, m); 13C-NMR
(CDCl3): 21.3, 24.7 (d, J=15.3), 25.4 (dd, J=37.2,
10.5), 128.8 (d, J=9.5), 129.1 (d, J=33.4), 129.6 (d,
J=9.5), 131.2 (d, J=2.9), 132.1 (d, J=8.6), 133.0 (d,
J=2.0), 138.4 (d, J=10.5); 31P-NMR (CDCl3): 14.9
(br), 15.8 (br).
3.1.21.3. Ph2P–(CH2)4–PCy2 (20d). Yield: 1.1 g (99%);
1H-NMR (CDCl3): 1.0–1.2, 1.27 (br), 1.36–1.50, 1.60–
1.70, 1.98 (m), 7.22–7.26, 7.31–7.36; 13C-NMR
(CDCl3): 20.0 (d, J=16.2), 25.5, 26.3, 26.3 (d, J=
17.2), 26.8 (d, J=11.4), 27.0 (dd, J=16.2, 12.4), 28.0
(d, J=7.6), 29.1 (dd, J=18.6, 11.9), 29.3 (d, J=14.3),
32.3 (d, J=12.4), 127.4 (d, J=11.4), 127.4, 131.7 (d,
J=18.1), 137.9 (d, J=13.4); 31P-NMR (CDCl3):
−15.9, −3.5.
3.1.20.2. Ph2P(BH3)–(CH2)4–P(BH3)(4-C6H4OCH3)2
(19c). Yield (crude): 6.6 g (84%). The crude product 19c
was used without purification. 31P-NMR (CDCl3): 12.9
(br), 16.1 (br).
3.1.22. [Rh(P–P%)(COD)]BF4 (21b, 21c, 21d and
[Rh(Cy2P–(CH2)4–PCy2)(COD)]BF4)
The complexes were prepared analogously to com-
pound 9 from Rh(COD)acac, the diphosphines P–P%
and HBF4 as previously reported.
3.1.20.3. Ph2P(BH3)-(CH2)4-P(BH3)Cy2 (19d). The
crude product was extracted with hot ethanol (500 ml).
The filtrate was cooled to 5°C giving 19d as a white
3.1.22.1. [Rh(Ph2P–(CH2)4–P(3,5-Me2C6H3)2(COD)]-
BF4 (21b). Yield: 73%; 1H-NMR (CDCl3): 1.63 (m),
2.14 (m), 2.30, 4.40 (d, J=32.7), 7.10 (br), 7.13 (br),
7.45–7.55; 13C-NMR (CDCl3): 21.9, 25.1 (d, J=16.2),
30.9 (d, J=16.2), 100.3 (dt, J=59.4, 8.3), 129.7 (d,
J=9.5), 131.2 (d, J=9.5), 131.8, 132.7 (d, J=15.3),
133.1 (d, J=16.2), 133.4, 133.5, 139.3 (d, J=9.5);
31P-NMR (CDCl3): 23.5 (dd, J=143.4, 38.9), 24.4 (dd,
144.6, 38.9).
1
solid. Yield: 1.5 g (21%); H-NMR (CDCl3): 1.22 (10H,
m), 1.48–1.82 (18H, m), 2.23 (2H, m), 7.41–7.51 (6H,
m), 7.63–7.70 (4H, m); 13C-NMR (CDCl3): 19.5 (d,
J=31.5), 25.6 (d, J=13.4), 25.7 (d, J=18.1), 26.0 (d,
4.8), 26.4, 27.1 (d, J=1.9), 27.2 (d, J=1.9), 27.3, 32.1
(d, J=32.4), 129.3 (d, J=9.5), 129.8 (d, J=55.3),
131.7 (d, J=2.9), 132.5 (d, J=8.6); 31P-NMR
(CDCl3): 16.0 (d, J=55.5), 25.0 (d, J=66.6).
3.1.22.2. [Rh(Ph2P–(CH2)4–P(4-C6H4OCH3)2)(COD)]-
BF4 (21c). Yield: 63%; 1H-NMR (CDCl3): 1.89 (d,
J=21.6), 2.10 (m), 2.45 (br), 2.62 (br), 2.73, 3.99 (m),
4.16, 4.70 (d, J=21.2), 7.31–7.36, 7.75–7.91; 13C-
NMR (CDCl3): 25.1, 26.0, 30.8, 31.8 (d, J=25.2), 32.4
(d, J=24.8), 56.0, 68.4, 100.6 (dt, J=46.7, 7.6), 115.4
(d, J=10.5), 123.4 (d, J=46.7), 129.7 (d, J=9.5),
131.8, 133.1 (d, J=42.0), 133.6 (d, J=10.5), 135.1 (d,
J=11.4), 162.3; 31P-NMR (CDCl3): 22.1 (dd, J=
142.9, 40.2), 25.1 (dd, J=145.0, 39.5).
3.1.21. Ph2P–(CH2)4–PR2 (20b, 20c and 20d)
To a cool solution (−10°C) of the phosphinoborane
Ph2P(BH3)-(CH2)4-P(BH3)R2 (19) (2.15 mmol) in
CH2Cl2 (25 ml) was added HBF4·OEt2 (3 ml, 7.2 M,
21.5 mmol). The resulting solution was stirred over
night at r.t. Then ether was added until the solution
became turbid. The mixture was washed twice with a
solution of NaHCO3. The aqueous solutions were ex-
tracted with ether and the combined organic fractions
were washed with water and brine. The etheric solution
was dried and evaporated to give a slightly yellow oil,
which crystallized after a long time.
3.1.22.3. [Rh(Ph2P–(CH2)4–PCy2)(COD)]BF4 (21d).
Yield: 56%; 1H-NMR (CDCl3): 1.33 (br), 1.48 (br), 1.78
(m), 1.70–1.90, 2.01 (br), 2.27 (br), 2.24 (br), 2.50 (br),
3.67 (m), 3.95 (br), 5.03 (br), 7.5 (m), 7.6 (m); 13C-
NMR (CDCl3): 13.9 (d, J=25.7), 14.3, 21.5 (dd, J=
7.6, 2.9), 23.6, 24.6, 25.2, 25.9 (d, J=8.6), 26.4 (d,
J=12.4), 26.6 (d, J=24.8), 27.9 (d, J=2.9), 29.1, 30.2
(d, J=21.0), 36.3 (d, J=21.0), 64.8, 67.0, 96.0 (dt,
J=137.3, 8.1), 128.2 (d, J=9.5), 130.3 (d, J=1.9),
130.6 (d, J=42.0), 131.9 (d, J=10.5); 31P-NMR
3.1.21.1. Ph2P–(CH2)4–P(3,5-Me2C6H3)2 (20b). Yield:
1
1.0 g (96%); H-NMR (CDCl3): 1.47 (4H, m), 1.93 (4H,
m), 2.20 (12H), 6.86 (2H, m), 6.92 (2H, m), 6.94 (2H,
m), 7.23 (6H, m), 7.30 (4H, m); 13C-NMR (CDCl3):
20.4, 26.6 (m), 127.3 (d, J=13.4), 127.4, 129.2, 129.4
(d, J=13.4), 131.7 (d, J=18.1), 136.7 (d, J=6.7),
137.8 (d, J=13.4); 31P-NMR (CDCl3): −16.0, −15.8.

V. Fehring et al. / Journal of Organometallic Chemistry 621 (2001) 120–129
129
(b) R. Selke, Enantiomer 2 (1997) 415. (c) R. Selke, J. Holz, A.
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[3] (a) I. Grassert, V. Vill, G. Oehme, J. Mol. Catal. A: Chem. 116
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[4] T.V. RajanBabu, T.A. Ayers, A.L. Casalnuovo, J. Am. Chem.
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[5] (a) R. Selke, J. Prakt. Chem. 329 (1987) 717. (b) R. Selke, J.
Organomet. Chem. 370 (1989) 249.
(CDCl3): 12.5 (dd, J=145.8, 34.8), 39.9 (dd, J=139.3,
34.0).
3.1.23. [Rh(Cy2P–(CH2)4–PCy2)(COD)]BF4
1
Yield: 73%; H-NMR (CDCl3): 1.2–1.4, 1.68–1.88,
2.11 (br), 2.29 (br), 3.67 (m), 4.81; 13C-NMR (CDCl3):
17.8 (t, J=11.0), 24.3, 26.0, 26.6, 27.5 (t, J=4.3), 28.1
(t, J=5.7), 29.5, 31.3, 32.0, 38.3 (t, J=10.0), 68.4, 93.2
(m); 31P-NMR (CDCl3): 24.5 (d, J=140.1).
[6] (a) U. Berens, C. Fischer, R. Selke, Tetrahedron:Asymmetry 6
(1995) 1105. (b) U. Berens, R. Selke, Tetrahedron:Asymmetry 7
(1996) 2055.
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(1987) 123.
[8] R. Selke, J. Organomet. Chem. 370 (1989) 241.
[9] T.E. Hogen-Esch, Adv. Phys. Org. Chem. 15 (1977) 154.
[10] J.M. Buriak, J.A. Osborn, Organometallics 15 (1996) 3161.
[11] M. Ludwig, R. Kadyrov, H. Fiedler, K. Haage, R. Selke, Chem.
Eur. J. (in press).
[12] (a) W. von Rybinski, K. Hill, Angew. Chem. 110 (1998) 1394.
(b) K. Hill, W. von Rybinski, G. Stoll, Alkyl Polyglycosides,
VCH Verlagsgesellschaft mbH, Weinheim, 1997.
[13] S. Masamune, W. Choy, J.S. Petersen, L.R. Sita, Angew. Chem.
97 (1985) 1; Angew. Chem. Int. Ed. Engl. 24 (1985) 1.
[14] L. Maier, Helv. Chim. Acta 51 (1968) 406.
[15] L. Poppe, W.E. Hull, J. Retey, Helv. Chim. Acta 76 (1993) 2367.
[16] W.R. Purdum, K.D. Berlin, J. Org. Chem. 40 (1975) 2801.
[17] A.L. Casalnuovo, T.V. RajanBabu, T.A. Ayers, T.H. Warren, J.
Am. Chem. Soc. 116 (1994) 9869.
[18] A.I. Breikss, P.M. Burke, J.M. Garner, W. Tam, US Patent (E.I.
Du Pont De Nemours and Co.) US 5710344, 1998, 9 pp.
[19] K. Sasse, Organische Phosphorverbindungen in Houben-Weyl
12/1 (1963) 197.
Acknowledgements
We would like to thank Professor A. Bo¨rner and
Professor G. Oehme for scientific advice and H. Bur-
neleit, K. Kortus as well as H. Fiedler for experimental
help. We are grateful to the BMBF (Fo¨rderkennzeichen
03D0053C5), the Max-Planck-Gesellschaft and the
Fonds der Chemischen Industrie for financial support.
For the gift of alkyl polyglycosides we are indebted to
Dr. W. von Rybinski and the Henkel KGaA.
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