Modular approach to new chiral monodentate diamidophosphite ligands. Application in palladium-catalyzed asymmetric hydrovinylation of styrene

Article abstract of DOI:10.1021/om100946a

A new group of chiral monodentate diamidophosphite ligands (2 P-N/1 P-O bond) based on diazaphospholidine backbones derived from N,N′- dibenzylcyclohexane-1,2-diamine (7) and N,N′-dimethylcyclohexane-1,2- diamine (8), and diazaphosphepine backbones derive

Full text of DOI:10.1021/om100946a

Organometallics 2011, 30, 115–128 115
DOI: 10.1021/om100946a
Modular Approach to New Chiral Monodentate Diamidophosphite
Ligands. Application in Palladium-Catalyzed Asymmetric
Hydrovinylation of Styrene
ꢀ
Isabel Ayora, Rosa M. Ceder, Mauricio Espinel, Guillermo Muller, Merce Rocamora,* and
Marta Serrano
´ ꢀ ´ ꢀ
Departament de Quımica Inorganica, Universitat de Barcelona, Martı i Franques 1-11,
E-08028 Barcelona, Spain
Received September 30, 2010
A new group of chiral monodentate diamidophosphite ligands (2 P-N/1 P-O bond) based on
diazaphospholidine backbones derived from N,N0-dibenzylcyclohexane-1,2-diamine (7) and N,
N0-dimethylcyclohexane-1,2-diamine (8), and diazaphosphepine backbones derived from N,
N0-dimethyl-[1,10-binaphthyl]-2,20-diamine (9) and various chiral alkoxy groups (coming from phenyl-
ethanol a, borneol b, methyllactate c, allylic alcohol d, and methanol e) were prepared. The ligands
have a highly modular structure, which is well suited to the synthesis of a small library. Preparation
was readily accomplished by the successive addition of pure enantiomeric substituted diamine and
pure enantiomeric alcohol to phosphorus trichloride. The corresponding diamidophosphite selenides
Se(7-9) were prepared and the JPSe was calculated in order to evaluate the σ-donor ability of the new
ligands. The reaction of [Pd(μ-Cl)(η3-2-CH3C3H4)]2 with the new diamidophosphite ligands (7-9)
led to the monomeric allylic neutral complexes 11-13. Two isomers appeared in solution due to the
R- or S-geometry around the palladium atom. The molecular structure determined by X-ray diffrac-
tion of the neutral complex [PdCl(η3-2-CH3C3H4)(7a)] (11a-(S,S,Sal)) showed a nonsymmetric coordina-
tion of the allyl moiety due to the greater trans influence of the phosphorus atom. The asymmetric
hydrovinylation reaction between styrene and ethylene was tested using filtered CH2Cl2 solutions
of [PdCl(η3-2-CH3C3H4)L] complexes and AgBF4 as catalytic precursors. The reaction performed at
15 °C and 15 bar of ethylene starting pressure led to good selectivities and moderate to good activities
of 3-phenyl-1-butene. The best results were obtained when the cationic catalytic precursor contained
the 9b-(R,Sal) diamidophosphite with a binaphthyl backbone and bornyloxy as the third substituent.
With this system the TOF reached 595 h-1 of 3-phenyl-1-butene, whereas the ee was 90% toward the
R-isomer.
Introduction
both monophosphane and diphosphane ligands have been
synthesized, with the latter being the best represented and
most successful of the ligands used in asymmetric catalysis.5
In recent years, however, monophosphorus chiral ligands
have received renewed interest, particularly those structures
that possess one or more P-heteroatom bonds. The vast major-
ity of them contain a cyclic structure in which the phosphorus
atom is a component of the heterocyclic ring, and this feature
is responsible for an increase in ligand stability. Particularly
interesting are chiral phosphonites, phosphites, and phos-
phoramidites, all based on the BINOL backbone, and these
have been successfully applied in several metal-catalyzed
asymmetric transformations.6-9
Transition-metal-catalyzed asymmetric transformations
play an important role in the synthesis of organic molecules
and in the industrial production of fine chemicals.1 In
general, a chiral ligand is used both to influence the reactivity
of the metal and to direct the stereochemical course of the
catalyzed reaction. Chiral phosphorus ligands are the most
widely used and have played a major role since the pioneer-
ing work of Knowles,2 Kagan,3 and Noyori.4 In particular,
*Corresponding author. E-mail: merce.rocamora@qi.ub.es.
(1) (a) Transition Metals for Organic Chemistry; Beller, M.; Bolm, C.,
Eds.; Wiley-VCH: Weinheim, 1998. (b) Catalytic Asymmetric Synthesis;
Ojima, I., Ed.; Wiley-VCH: New York, 2000.
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Commun. 1972, 10. (b) Vineyard, V. D.; Knowles, W. S.; Sabacky, M. J.;
Bachman, G. L.; Weinkauff, O. J. J. Chem. Soc. 1977, 99, 5946. (c) Knowles,
W. S. Acc. Chem. Res. 1983, 16, 106.
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H. B.; Dang, T. P. J. Am. Chem. Soc. 1972, 94, 6429. (c) Kagan, H. B.; Langlois,
N.; Dang, T. P. J. Organomet. Chem. 1975, 90, 353.
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Wiley-VCH: Weinheim, 2008.
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r
2010 American Chemical Society
Published on Web 12/08/2010
pubs.acs.org/Organometallics

116 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
Less research has been reported on the synthesis and
application of chiral diamidophosphite ligands with two
P-N bonds and one P-O bond. It is presumed that these
compounds have different properties from phosphorami-
dites or phosphites when applied as ligands in asymmetric
catalysis. For example, nitrogen substituents create more
steric bulk around the phosphorus than oxygen, since nitro-
gen substitution may be greater. Furthermore, diamidopho-
sphites are assumed to have more electron-rich phosphorus
than phosphoramidites or phosphites.
Figure 1. General structure of diamidophosphite ligands I.
sites of diversity and their synthesis can be readily accom-
plished through two modular synthetic paths.
The synthesis and characterization of some diamidopho-
sphites with different heterocyclic backbones have been
reported by Pfaltz,10 Tsarev,11 Buono,12 and Reetz13 as well
as some ligands that are structurally related, such as the
diamidophosphines reported by Spilling,14 Wills,15 and
Piarulli,16 and the triamidophosphites reported by Piarulli16
and Leitner.17 All of these new ligands have been applied to
different asymmetric processes, such as palladium-catalyzed
allylic alkylation,10-12,13b,14,15 rhodium hydroformylation and
hydrogenation,13 iridium hydrogenation,10 and enantio-
selective copper-catalyzed conjugate addition of diethylzinc
to cyclohexenone.12,17 Alexakis18 and co-workers developed
the synthesis of diamidophosphites in order to determine the
enantiomeric excess of chiral alcohols, amines, thiols, and
carboxylic acids. Very few examples of the coordination chem-
istry of these kinds of ligands are reported in the literature;
only Tsarev11a and Buono12 synthesized allylic palladium com-
plexes with diamidophosphite ligands, and Spilling14 pre-
pared some platinum coordination compounds with a dia-
midophosphine ligand.
These new modular chiral ligands I can be tested in several
asymmetric catalytic processes, but their monodentate char-
acter prompted us to study their behavior in the asymmetric
hydrovinylation of styrene, since this would serve as a proto-
typical test case. We carried out the preparation and char-
acterization of the neutral allylic palladium(II) compounds
to be used as catalytic precursors in the reaction.
The catalytic asymmetric hydrovinylation reaction is a
heterodimerization between ethylene and an activated olefin,
usually conjugated dienes (styrene and other vinylarenes) or
strained olefins (norbornene), catalyzed by a transition metal
complex.19 The codimerization product contains a stereo-
genic carbon atom, so the reaction is amenable to enantio-
control. The process is of much interest in enantioselective
synthesis because it provides a short route to 2-arylpropionic
acids, the most important family of nonsteroidal antiinflam-
matory drugs, including naproxen or ibuprofen.20 More
recently it has also been employed in the stereoselective con-
struction of benzylic all-carbon quaternary stereocenters,21 a
structural motif present in pharmacologically important com-
pounds, and in the short synthesis of natural products.22 In
spite of its enormous potential, hydrovinylation is still an
underused reaction even in the synthesis of fine chemicals.
This is due to the presence of some side reactions, dimeriza-
tion and isomerization, which require a subtle fine-tuning of
the catalyst to obtain good selectivity. This process is cata-
lyzed by a variety of transition metal compounds, nickel and
palladium being the most frequently used, and the catalytic
cycle proposed for these metal systems shows that the active
catalyst is most probably an unsaturated metal hydride
stabilized by one monodentate phosphine.19c,23a It must be
noted, however, that the presence of the nickel hydride inter-
mediate has been recently questioned by a theoretical study
of RajanBabu and co-workers,23b who suggest a direct β-H
transfer instead of a β-elimination. Excellent regioselectiv-
ities are obtained with vinylarenes such as styrene or vinyl-
naphthalene due to the allylic nature of the intermediate
proposed. Very good enantioselectivities were initially ob-
tained by Wilke,24 and more recently by the groups of Vogt
Here, we report the synthesis and characterization of chiral
diamidophosphite ligands of general formula I (Figure 1),
with binaphthyl or cyclohexyl R1 backbones and with var-
ious substituents R2 and R3, since they display several potential
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Article
Organometallics, Vol. 30, No. 1, 2011 117
and Cavell,25 Gibson,26 Rajanbabu,20b,21c,27 Leitner,28 and
Zhou,29 using phosphines, planar chromium phosphines,
phosphinites, or phosphoramidites as stabilizing ligands
with nickel and palladium systems. Our research group stud-
ied the model reaction using nickel and palladium precursors.
The initial study provided evidence of the blocking effect of
inert bidentate ligands.30a Further research with allylic pal-
ladium precursors containing P-stereogenic phosphines30b-e
and chiral aminophosphines30f enabled the enantioselective
version of the process to be studied.
Results and Discussion
Diamidophosphite Preparation. The structure of the chiral
diamidophosphite ligands allows easy adjustment of steric
and electronic properties, through modification of the nature
and chirality of the C2 diamine backbone (R1), the nature of
the amine substituent (R2), and the nature and chirality of
the alkoxy group (R3) (Chart 1).
Chiral diamidophosphite ligands were prepared as re-
ported in the literature,10a,11a,13a,18d via a two-step reac-
tion (Scheme 1).
The reaction of phosphorus trichloride with the enantio-
merically pure chiral disubstituted diamine in the presence of
excess triethylamine led to the preparation of the hetero-
cyclic chloride derivative. The formation of 4, 5, and 6 was
monitored by phosphorus NMR spectroscopy (4, 5: δ =
174.5 ppm and 6: δ = 204.9 ppm). When the PCl3 signal
disappeared, the stoichiometric amount of the correspond-
ing chiral alcohol (R3H) was added until completion of the
reaction. The last step produced the diamidophosphites 7a-d,
8b, and 8e with a diazaphospholidine backbone and 9b with a
diazaphosphepine backbone.
Chart 1. Building Blocks for the Synthesis of Diamidophosphite
Ligands
The four diastereomers of ligands 7a (7a-(R,R,Ral), 7a-
(R,R,Sal), 7a-(S,S,Sal), 7a-(S,S,Ral)) and two diastereoisomers
of ligands 7b (7b-(R,Ral), 7b-(R,Sal)) and 9b (9b-(R,Ral), 9b-
(R,Sal)) were prepared in order to study the match/mismatch
effects of the two chiral units in the catalytic asymmetric
process. The racemic 7a-(rac,racal) and 7a-(rac,Sal) ligands
were prepared in order to study the separation of the corre-
sponding diastereomeric allyl palladium complexes by frac-
tional crystallization. Ligands 7c and 7d were prepared to
test the potential hemilability coming from a second donat-
ing group, the double bond and oxygen atom, respectively.
Compounds 7a-d, 8b, 8e, and 9b were obtained as sensi-
tive pure oils, stored under nitrogen atmosphere, and used in
the synthesis of palladium(II) complexes without further
treatment. The new ligands have been characterized by mass
Scheme 1

118 Organometallics, Vol. 30, No. 1, 2011
Table 1. Selected NMR Dataa (δ in ppm, in CDCl3) for Ligands 7-9
Ayora et al.
δ 1H (diamine backbone)
δ 1H (R3)
O-C*H
0
0
ligand
δ 31
P
H1, H1 , H2, H2
H3, H4
7a-(R,R,Ral)
7a-(S,S,Sal)
þ135.2 (s)
þ140.7 (s)
4.17-4.04 (om, 2H)
2.91 (m)
2.44 (m)
4.95 (dq; JHH = 8.8, JHP = 6.4)
3.96 (dd; JHH = 15.6, JHP = 12, 1H)
3.48 (dd; JHH = 15.2, JHP = 9.6, 1H)
4.23 (pt, JHH = JHP = 13.5, 1H)
4.17 (pt, JHH = JHP = 13.5, 1H)
3.82 (pt; JHH = JHP = 14.8, 1H)
3.52 (dd; JHH = 15.2, JHP = 10.4, 1H)
4.28 (dd; JHH = 15.3, JHP = 11.7; 1H)
4.20 (t, JHH = JHP = 14.1; 2H)
3.73 (dd; JHH = 15.3, JHP = 8.4; 1H)
4.34 (dd; JHH = 16, JHP = 13.6; 1H)
4.11 (dd; JHH = 15, JHP = 12; 2H)
3.76 (dd; JHH = 15.2, JHP = 10.8; 1H)
4.40-4.15 (om; 2H)
7a-(R,R,Sal)
7a-(S,S,Ral)
2.99 (m)
2.46 (m)
4.86 (m)
7b-(R,R,Ral)
7b-(R,R,Sal)
þ135.9 (s)
þ142.4 (s)
2.92 (m)
2.46 (m)
4.09 (m)
2.95 (m)
2.47 (m)
3.98 (m)
7c-(R,R,Sal)
7d-(R,R)b
þ140.4 (s)
þ137.1 (s)
þ144.0 (s)
3.07 (m)
2.51 (m)
3.00 (m)
2.50 (m)
2.63 (m)
2.29 (m)
4.40-4.15 (om)
4.00-3.80 (om; 2H)
4.35-3.82 (om; 4H)
O-CH2
4.35-3.82 (om, 2H)
O-C*H
4.02 (m)
8b-(R,R,Sal)
Me1, Me2
2.60 (d; JHP = 13.2; 3H)
2.42 (d; JHP = 14; 3H)
2.61 (d; JHP = 14; 3H)
2.48 (d; JHP = 14; 3H)
2.88 (d; JHP = 12; 3H)
2.81 (d; JHP = 8; 3H)
2.91 (d; JHP = 13.6; 3H)
2.89 (d; JHP = 9.6; 3H)
8e-(R,R)
þ136.0 (s)
þ178.6 (s)
þ177.6 (s)
2.65 (m)
2.24 (m)
O-CH3
3.36 (d; 9.6; 3H)
O-C*H
4.32 (m)
9b-(R,Ral)
9b-(R,Sal)
4.27 (m)
a 1H NMR: 298 K, 400 MHz. 31P NMR: 298 K, 101,2 MHz. Multiplicity: s, singlet; d, doublet; t, triplet; q, quartet; p, pseudo; m, multiplet; om,
overlapped multiplets. Coupling constants are given in Hz and are shown in parentheses after the multiplicity. See figure below for atom numbering.
b Broad signals for 1H spectrum
1
spectrometry and 13C, H, and 31P NMR spectroscopy.
showed loss of the C2 symmetry of the starting substituted
diamines. Thus, for ligands 7 the four benzylic protons were
unique and exhibited coupling with the geminal proton and
the phosphorus atom. Protons bonded to the cyclohexyl
chiral carbon always appeared as two multiplets in contrast
to one multiplet in the free parent amine. For diazapho-
spholidines 8 and diazaphosphepine 9 the methyl amino
substituents appeared as two different doublets, showing cou-
pling with the phosphorus atom.
Selected NMR data are shown in Table 1.
The 31P chemical shift values were in the range reported for
diamidophosphites5 and appeared to be mostly influenced
by the nature of the amine scaffold. It is worth noting the
different chemical shift found for the diastereoisomers of the
same ligand (7a-(R,R,Ral) and 7a-(R,R,Sal), 7a-(S,S,Sal) and
7a-(S,S,Ral), 7b-(R,Ral) and 7b-(R,Sal), 9b-(R,Ral) and 9b-
(R,Sal)), showing that the different spatial orientation of the
substituents on the chiral alkoxy group influenced the 31P
chemical shift value.18d,e To assign 1H NMR spectra unequi-
vocally, it was necessary to record the two-dimensional
experiment HSQC. All the diamidophosphites synthesized
Selenide Derivatives. A simple means of evaluating the
σ-donor ability of the diamidophosphites is to measure the
magnitude of 1JSeP in the 77Se isotopomer of the correspond-
ing diamidophosphite selenide. It has been reported that
1
poorly donating phosphine will exhibit values of JSeP that
are larger than those for electron-rich phosphines.31
We prepared the corresponding selenides of the new
diamidophosphites Se(7-9) and of the structurally related
ligands 7f14 and 9e13a reported in the literature, by simply
reacting the phosphorus compounds with elemental selenium
in dichloromethane at room temperature (Scheme 2).
The selenide compounds were characterized in situ by 31P
NMR spectroscopy. In each case a single new resonance that
exhibited coupling to 77Se, at higher fields than free diami-
dophosphites, was observed (Table 2).
€
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From the magnitude of JSeP it is possible to draw some
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~
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Article
Organometallics, Vol. 30, No. 1, 2011 119
Scheme 2
Table 2. Selected 31P NMR Dataa for Selenide Derivatives
Se(7-9)
Scheme 3
SeL
δ31P SeL
JSeP SeL
Se7a-(R,R,Sal)
Se7a-(S,S,Ral)
Se7a-(S,S,Sal)
Se7a-(R,R,Ral)
Se7b-(R,R,Sal)
Se7b-(R,R,Ral)
Se7c-(R,R,Sal)
Se7d-(R,R)
87.3
86.6
884
881
88.8
85.8
87.4
88.3
87.7
85.3
87.6
89.5
91.9
93.2
49.5
858
870
874
888
817
863
872
866
883
891
727
Se7f-(R,R)
Se8b-(R,R,Sal)
Se8e-(R,R)
Se9b-(R,Sal)
Se9b-(R,Ral)
Se9e-(R)
JHP =6.4; 4.40 ppm, dt, JHH =16, JHP =6; 4.08 ppm, dt,
JHH=16.4, JHP = 2.4).
SeBinepine-(S)b
a 31P {1H} NMR: 298 K, 101.2 MHz, CH2Cl2. δ in ppm. Coupling
Preparation of Allylic Palladium(II) Complexes [PdCl(η3-2-
CH3C3H4)L)] (11-14). Neutral allylic palladium complexes
have been prepared with the new diamodiphosphite 7a-d,
8b, 8e, and 9b ligands and also with the following structur-
ally related ligands reported by other authors, diamido-
phosphine 7f-(R,R),14 diamidophosphite 9e-(R),13 and phos-
phine Binepine-(S),32a with the aim of studying the coordi-
nation chemistry and dynamic behavior in solution of the
new neutral π-allylic complexes. The neutral compounds were
used to prepare the corresponding cationic allylic catalytic
precursors and to study how the nature of the different sub-
stituents in the phosphorus ligands affected activity and
selectivity in the hydrovinylation reaction. Very few exam-
ples of allylic palladium(II) complexes with diamidopho-
sphite ligands have been reported in the literature.11a,12
The allylic complexes 11a-d, 11f, 12b, 12e, 13b, 13e, and
14 were prepared by reaction at low temperature of the well-
known bridged chloride complex [Pd(μ-Cl)(η3-2-CH3C3H4)]2
with the appropriate stoichiometric amount of the ligand
as reported in the literature30d,f for similar compounds
(Scheme 4).
constants in Hz. b Reported value.32
substituted diamino backbone and different R3 group, the
lowest 1JSeP value was observed when the more sterically de-
manding bornyloxy group was bonded to the phosphorus
atom. The presence of bulky substituents at phosphorus
resulted in a decrease in the s character of the lone pair as a
result of the widening of intervalence angles.31a Comparing
ligands with different backbones (8b vs 9b), a slightly better
σ-donor character was seen for those with a cyclohexyl rather
than a binaphthyl backbone. The 1JSeP also had interesting
stereochemical dependencies; thus, different diastereoisomers
1
showed different values for JSeP (see: Se 7b-(R,R,Sal) vs
Se7b-(S,S,Ral); Se9b-(R,Sal) vs Se9b-(S,Ral)). Higher cou-
pling constant values were registered for diamidophosphite
(two P-N bonds and one P-O bond) compared to diami-
dophosphine ligands 7f (two P-N bonds and one P-C bond)
and Binepine phosphine ligand (three P-C bonds), indicat-
ing that the more electronegative substituents bonded to
the phosphorus atom, the lower the σ-donor ability of the
ligand.
The new compounds were characterized, in the solid state,
by elemental analysis, and mass spectroscopy where neces-
Palladium Complexes. Preparation of [PdCl2L2)] (10). To
examine the complexing capacity of the diazaphospholidine
ligands and to obtain further structural information, one
coordination palladium(II) complex was prepared. The re-
action of diazaphospholidine 7b-(R,R,Sal) with [PdCl2(cod)]
in CH2Cl2 gave the palladium complex 10 (Scheme 3).
No crystals suitable for X-ray determination were ob-
tained, but we studied the structure of complex 10 in solu-
tion. The 31P NMR spectrum showed only one signal (δ =
91.84 ppm), suggesting the presence of a unique complex,
and this was assigned as trans on the basis of the 1H NMR
spectrum: benzylic hydrogen atoms appeared as four doub-
lets of triplets due to coupling with geminal nonequivalent
protons and the two phosphorus atoms in trans position
(4.96 ppm, dt, JHH=16, JHP= 6.8; 4.85 ppm, dt, JHH=16,
1
sary. H and 31P NMR spectroscopy allowed us to charac-
terize these complexes in solution. Some relevant NMR spec-
tral data are summarized in Tables S1 and S2. 31P NMR
spectra showed two sharp signals, with approximately the
same ratio, arising from the two well-known33 isomers
formed due to the different disposition of the chiral ligand
and the allylic group around the metal center. For complexes
(32) (a) Gladiali, S.; Dore, A.; Fabbri, D.; de Lucchi, O.; Manassero,
M. Tetrahedron: Asymmetry 1994, 4, 511. (b) Erre, G.; Enthaler, S.; Junge,
K.; Gladiali, S.; Beler, M. J. Mol. Catal. A: Chem. 2008, 280, 148.
(33) (a) Pregosin, P. S.; Salzmannn, R. Coord. Chem. Rev. 1996, 155,
35. (b) Faller, J. W.; Stokes-Huby, H. L.; Albrizzio, M. A. Helv. Chim. Acta
2001, 84, 3031.

120 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
Scheme 4
11f, 13b-(R,Ral) and 13b-(R,Sal), the ratio of isomers ob-
tained from the 31P NMR spectra was 1:1.5, 1:1.4, and 1:1.7,
respectively. Probably, the Ph substituent of the phosphorus
ligand in 11f and the bulky b group (bornyloxy) in 13b led to
some discrimination between the two isomers. The phos-
phorus chemical shifts of complexes with diamidophosphite
ligands lay upfield compared to those of the free ligand, but
complexes with diamidophosphine, 11f, and phosphine,
14-(S), lay downfield. Gavrilov11a found the same relation of
chemical shifts in complexes with diamidophosphite chiral
ligands.
the P atom appeared as a doublet because of phosphorus
coupling.
To elucidate the solution structure of these complexes
and their dynamic behavior, 2D NOESY experiments were
carried out for complexes 11a-(R,R,Ral), 11a-(R,R,Sal),
11b-(R,R,Sal), 11f-(R,R), 12b-(R,R,Sal), 13b-(R,Ral), 13b-
(R,Sal), 13e-(R), and14-(S). Only NOE contacts between allylic
protons and the diamidophosphite ligand were observed for
complexes 13b. Nevertheless, interesting exchange signals
between allylic protons were observed. Exchange between
syn/anti allylic protons was observed with the pair in cis
position to the phosphorus atom for all the complexes
studied. The pair that is in trans position exchanges only
between syn/syn and anti/anti protons, in accordance with a
selective opening of the palladium carbon bond trans to the
phosphorus atom. This can be observed in analogous com-
pounds30d,f,34b and suggests the well-known η3-η1-η3 iso-
merization process. Cross-peaks that can be assigned to the
whole apparent rotation were observed only for complexes
13b-(R,Ral), 13b-(R,Sal), and 13e-(R), with ligands contain-
ing the binaphthyldiamino backbone, and 14-(S), with the
Binepine phosphine ligand. Exchange signals between benzylic
hydrogens of different isomers in complexes 11a-(R,R,Ral),
11a-(R,R,Sal), 11b-(R,R,Sal), 11f (R,R), and 14-(S), as well as
between methylamino hydrogens in 13b-(R,Ral), were also
detected. For 13b-(R,Sal) the methylamino signals were too
close to clearly detect exchange cross-peaks.
We tested the separation of the stereoisomers of 11a-(rac,
racal) species by fractional crystallization. Reaction of [Pd(μ-
Cl)(η3-2-CH3C3H4)]2 with the racemic diazaphospholidine
7a-(rac,racal) led to a solution where a mixture of isomers
(11a-(R,R,Sal), 11a-(R,R,Ral), 11a-(S,S,Ral), 11a-(S,S,Sal))
was present, confirmed by 31P NMR spectroscopy (signals at
130.7, 129.9, 126.9, 126.4 ppm with a similar ratio). After
precipitation with ether, a solid that presented signals at
130.7 and 129.9 ppm was obtained; a second precipitation
with pentane enabled the crystallization of a solid with
signals at 126.9 and 126.3 ppm, the first of which could be
Bidimensional NMR heterocorrelation 1H-13CandNOESY
experiments were important for assigning the different sig-
nals of the 1H spectra; nevertheless a complete correlation of
all the protons of one isomer was not possible in any of the
complexes. Relative to the coordinated phosphorus ligand, it
is worth noting that all the proton signals of the diamino
backbone shifted to lower fields than those of the free ligand.
Complexes 11a-d,f, with a dibenzylcyclohexyldiamino back-
bone, showed eight signals for the benzylic protons usually
overlapped, both with each other and also with the trans-
syn allylic hydrogen atoms. The same trend was observed
for complex 14-(S) with a Binepine ligand. Complexes 12b,
12e, and 13b showed two signals assigned to methyl sub-
stituents in the diamino backbone, but for 13e four well-
defined doublets were detected. Related to the allylic group,
1H NMR spectra showed two sets of signals for each syn and
anti proton and two singlets for the methyl substituent,
confirming the presence of the two isomers. Allylic terminal
hydrogen atoms located on the carbon atom trans to the
phosphorus atom appeared at lower field than those in the cis
position, as has generally been observed for similar com-
pounds.30d,f,34 Terminal anti protons in trans position to
(34) (a) Akermark, B.; Krakenberg, B.; Hanson, S.; Vitagliano, A.
Organometallics 1987, 6, 620. (b) Boele, M. D. K.; Kamer, P. C. J.; Lutz, M.;
Spek, A. L.; de Vries, J. G.; van Leeuwen, P. W. N. M.; van Strijdonck, G. P. F.
Chem. Eur. J. 2004, 10, 6232.

Article
Organometallics, Vol. 30, No. 1, 2011 121
Figure 2. ORTEP drawing of the molecular structure of the compound 11a-(S,S,Sal) shown at 50% probability. Hydrogen atoms are
omitted for clarity.
˚
Table 3. Selected Bond Lengths (A) and Angles (deg) for Complex
11a-(S,S,Sal)
assigned to the pair of enantiomers 11a-(R,R,Sal) and 11a-(S,
S,Ral), and the second to the 11a-(R,R,Ral) and 11a-(S,S,Sal)
pair. We tested the preparation of pure diatereoisomers by
reaction of the palladium dimer with the diazaphospholidine
7a-(rac,Sal) under the same conditions, but the separation by
fractional crystallization was not possible, and only a mix-
ture of both diastereoisomers was obtained.
Crystals of sufficient quality for X-ray diffraction mea-
surements were obtained from a mixture of dichloromethane
and ether solution of complex 11a-(S,S,Sal). Figure 2 shows
an ORTEP view, and Table 3 gives a list of selected bond
lengths and bond angles.
The palladium atom showed a distorted square-planar
coordination, bonded to one phosphorus, one chloro, and
two terminal allylic carbon atoms. The distances and angles
between the atoms of the coordination sphere were in the
range expected for this type of allylic complex.34b,35 The
longer Pd-C length trans to the phosphorus atom is in
agreement with the stronger trans influence of the diamido-
phosphite ligand relative to the chloro ligand. The source
of the different environment of the two nitrogen atoms with
R-configuration in the molecular structure is in the confor-
mation adopted by the phenyl group of the 2-phenylethoxy
moiety. This phenyl group is placed over the C8 atom in the
base of the N7 pyramid, obliging the two angles with P1 and
C1 to reach 120°.
Pd-P1
2.2550(6)
2.3728(6)
2.219(3)
2.182(2)
2.089(2)
95.02(2)
109.80(6)
113.70(7)
121.53(7)
112.02(14)
120.58(15)
120.06(18)
352.66
P1-O23
1.6132(16)
1.6681(19)
1.688(2)
1.392(3)
1.427(3)
111.28(9)
105.73(9)
93.70(9)
110.27(14)
116.91(16)
116.08(18)
343.26
Pd-Cl1
P1-N7
Pd-C32
P1-N15
Pd-C33
C32-C33
Pd-C34
C33-C34
Cl1-Pd-P1
O23-P1-Pd
N7-P1-Pd
N15-P1-Pd
P1-N7-C1
P1-N7-C8
O23-P1-N7
O23-P1-N15
N7-P1-N15
P1-N15-C2
P1-N15-C16
C2-N15-C16
P
C1-N7-C8
angles Ν15
P
angles Ν7
It was possible to compare molecules with POON35-38
(phophoramidites), PNNO13,18d,39,40 (diamidophosphites), or
PNNN17b (phosphorus triamides) bonds, free ligands,17b,36,38
ligands coordinated to a transition metal,35,39,40 and ligands
bonded to borane,13b,38b selenium,37 or sulfur18d atoms. It was
observed that the P-O and P-N bond lengths were very
similar, but the bond length was not always shorter with the
more electronegative atom. With POON ligands, coordination
reduces bond length, significantly more so in borane or
selenium derivatives than in metal complexes. From the
limited number of structures containing the PNNO skeleton
we conclude that BH3 or metal coordination led to similar
bond lengths. The degree of sp2 character of the N bonds
is a matter for discussion. Free ligands37,38a with a POON
skeleton show a pronounced planarity of the CCNP plane,
but coordination always led to an increase of the pyramida-
lization around the nitrogen atom. Thus, the nitrogen atom
seems to increase the sp3 contribution of the N-C and N-P
bonds on coordination.
(35) (a) Filipuzzi, S.; Pregosin, S. P.; Albinati, A.; Rizzato, S.
Organometallics 2006, 25, 5995. (b) Shintani, R.; Park, S.; Shirozu, F.;
Murakami, M.; Hayashi, T. J. Am. Chem. Soc. 2008, 130, 16174.
(36) Holscher, M.; Francio, G.; Leitner, W. Organometallics 2004, 23,
5606.
(37) Murai, T.; Inaji, S.; Morishita, K.; Tokunaga, M.; Obora, Y.;
Tsuji, Y. Chem. Lett. 2006, 35, 1424.
(38) (a) Spek, A. L. Private communication, 2001. Cambridge Crystal-
lographic Data Centre code CSD OCULED. (b) Spek, A. L. Private com-
munication, 2001. Cambridge Crystallographic Data Centre code CSD
OCULAZ.
Hydrovinylation Reaction. Allylic complexes stabilized
with one monodentate phosphine have proved to be very
(39) Kawamura, K.; Nakazawa, H.; Miyoshi, K. Organometallics
1999, 18, 4785.
(40) Nakazawa, H.; Kawasaki, T.; Miyoshi, K.; Suresh, C. H.; Koga,
N. Organometallics 2004, 23, 117.

122 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
useful as catalytic precursors in the hydrovinylation reaction
since the metal phosphine ratio is 1:1 and the cleavage of the
allyl substituent leads to the actual catalyst that initiates
heterodimerization. The model reaction involves codimer-
ization between styrene and ethylene, forming 3-phenyl-1-
butene. In addition, variable amounts of dimerization of
either styrene or ethylene can be found. The isomerization of
the 3-phenyl-1-butene to the more stable 2-phenyl-2-butene
could appear as a consecutive process when the active
catalyst is a palladium hydride species (Scheme 5).
The excellent regioselectivities obtained were a conse-
quence of the allylic nature of the intermediate. Since only
one monodentate ligand may be coordinated to the metal,
the factors determining the discrimination capacity of the
catalyst remain poorly defined. A concerted effort was
made in the preparation of hemilabile ligands to stabilize
the active species, thus contributing to improved diatereose-
lective discrimination and enhancing the selectivity of the
process.21b,23b,25a,28,41
evaluating the results obtained in the catalytic process. It has
been reported30f,34a that similar solutions of cationic allylic
palladium(II) complexes with different phosphine and ami-
nophosphine ligands undergo symmetrization, leading to
mixtures of three different species. The relative amount of
each one seems to be related mainly to steric over electronic
parameters of the ligands.
Using 31P NMR spectroscopy, we monitored the solutions
of some selected cationic complexes of type [Pd(η3-2-
CH3C3H4)LS]BF4, with the new diamidophosphite ligands
prepared in this study. Thus, a CH2Cl2 solution of the
neutral complex was reacted with a stoichiometric amount of
AgBF4 in the presence of a 10-fold excess of styrene or
acetonitrile, as shown in Scheme 6.
Testing the symmetrization reaction with acetonitrile or
styrene as the labile ligand for complex 11f (L=7f-(R,R)),
the same results were obtained, showing only the formation
of the mixed [Pd(η3-2-CH3C3H4)LS]BF4 species. Therefore,
we used styrene or acetonirile depending on convenience.
Solutions of cationic complexes with 7a-(R,R,Ral), 7b-(R,R,
Sal), 7d-(R,R), and 7f-(R,R) ligands showed only two singlets
in a 1:1 ratio, corresponding to the two isomers of the mixed
complex. However, the solution with complex [Pd(η3-2-
CH3C3H4)LS]BF4, L = 8b-(R,R,Sal), showed two separate
singlets belonging to the isomers of the mixed cationic
complex, and two doublets according to the presence of the
bisdiamidophosphite cationic complex [Pd(η3-2-CH3C3H4)-
L2]BF4. The ratio of the mixed/bisligand cationic complexes
was 5:1. These results suggest that cationic complexes con-
taining the diamidophoshite 8b-(R,R,Sal), with the smallest
amino substituent (methyl vs benzyl), are the only ones that
undergo symmetrization. From these results, we conclude
that only cationic complexes with 8b and 8e ligands, contain-
ing the dimethylcyclohexyl fragment, are prone to present
the symmetrization reaction to a significant extent.
Solutions of cationic mixed complexes [Pd(η3-2-CH3C3H4)-
LS]BF4 obtained “in situ”, in CH2Cl2, from neutral com-
plexes 11-14 and AgBF4 in the presence of styrene were used
as catalytic precursors in the hydrovinylation reaction. The
study of the species present in these solutions is important for
Scheme 5
The hydrovinylation reaction was carried out using a [Pd]/
styrene ratio of 1:1000, CH2Cl2 as solvent, 15 bar of starting
ethylene pressure, and at 15 °C. The products of the catalytic
process were analyzed after 60 or 360 min reaction. The
results obtained with the different precursors are shown in
Table 4.
Good reproducibility and excellent selectivity toward
codimer A at low conversions were obtained in accordance
Scheme 6

Article
Organometallics, Vol. 30, No. 1, 2011 123
Table 4. Hydrovinylation of Styrene Catalyzed by [Pd(η3-CH3C3H4)LS]BF4 Precursorsa
entry
L
time (min)
dimer (%)
codimerb (%)
selectivityc (%)
TOFd
ee (%)
1
2
3
4
5
6
7
8
7a-(R,R,Ral)
7a-(R,R,Ral)
7a-(R,R,Sal)
7a-(R,R,Sal)
7a-(S,S,Sal)
7a-(S,S,Sal)
7a-(S,S,Ral)
7a-(S,S,Ral)
7b-(R,R,Ral)
7b-(R,R,Ral)
7b-(R,R,Sal)
7b-(R,R,Sal)
7b-(R,R,Sal)
7c-(R,R,Sal)
7c-(R,R,Sal)
7c-(R,R,Sal)
7d-(R,R)
60
360
60
360
60
360
60
360
60
360
60
180
360
60
360
360
60
360
60
360
60
360
60
360
60
360
60
120
360
60
360
60
2.6
3.1
0.5
1.8
0.5
1.8
0.6
1.2
0.4
1.1
0.7
0.9
1.1
0.5
0.6
0.9
0.1
0.2
5.6
5.7
0.5
1.4
0.2
1.5
2.0
1.1
3.0
2.4
1.6
1.1
3.3
7.8
11.3
7.2
50.5
7.4
36.0
5.2
94.9
77.9
98.0
89.0
98.8
79.0
98.5
87.2
97.7
74.1
96,4
87.7
67.0
97.8
93.7
90.7
72
84
74
60
52
90
75
70
109
124
156
130
114
40
6 (R)
11 (R)
2 (S)
5 (S)
12 (S)
2 (S)
54.1
7.5
41.8
11.6
77.0
15.3
44.5
81.9
4.3
0
9
28 (S)
32 (S)
25 (R)
23 (R)
19 (R)
10
11
12
13
14
15
16e
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
12.0
20.2
19
29
4 (R)
2 (R)
7d-(R,R)
7f-(R,R)
7f-(R,R)
8b-(R,R,Sal)
8b-(R,R,Sal)
8e-(R,R)
0.5
14.9
33.2
2.2
15.2
0.5
100
0.8
149
55
19
22
96.4
80.1
100
94.7
100
91.3
95.8
88.1
92.9
84.3
76.0
98.9
80.4
96.3
79.7
7 (S)
6 (S)
23 (S)
5
6
8e-(R,R)
6.7
7 (S)
80 (R)
80 (R)
90 (R)
90 (R)
90 (R)
25 (R)
25 (R)
25 (S)
23 (S)
9b-(R,Ral)
9b-(R,Ral)
9b-(R,Sal)
9b-(R,Sal)
9b-(R,Sal)
9e-(R)
9e-(R)
Binepine-(S)
Binepine-(S)
45.0
75.4
62.7
84.8
91.5
9.4
67.7
11.3
48.7
428
122
595
378
149
90
114
119
80
360
a Reaction carried out at 15 °C, 15 bar of initial pressure of ethylene in 10 mL of CH2Cl2, ratio styrene/Pd = 1000:1. b Codimer: Total amount of
codimers (A þ B þ C): see Scheme 5. c Selectivity: % of 3-phenyl-1-butene with respect to the codimers. d TOF = (mol codimer)(mol neutral complex)-1
(h)-1 e 30 bar of initial pressure of ethylene.
.
with previous research.29,30b-30d Dimerization of styrene is
low and does not increase with reaction time, suggesting that
the dimer is produced in the preparation of the precursor. To
confirm the origin of the styrene dimer, we reproduced a
hydrovinylation experiment but without the pressuriza-
tion of ethylene using precursors containing the ligands 7a-
(R,R,Sal) and 7f-(R,R). Monitoring the reaction by GC
showed that dimerization increases with time and that the
initial value of the dimer obtained at 30 min reaction was
similar to that obtained in the hydrovinylation reaction
(3.8% for 7f-(R,R) and 0.9% for 7a-(R,R,Sal)).
at 60 min reaction). As has been reported, for Ni22b,43 and
Pd21b systems the use of a monophosphine that carries a
hemilabile group might have an advantage, since such a
group could stabilize the putative cationic intermediate by
internal coordination, yielding better activities and selectiv-
ities of the process. However, the double bond of the allyloxy
substituent in 7c and the oxygen atoms of the oxylactate
group in 7d ligands presumably compete strongly with the
substrates for the vacant coordination site in the active
species, thus blocking the catalytic process, as described by
Rajanbabu.42
Data in Table 4 show a decrease for all the precursors of
the selectivity toward 3-phenyl-1-butene (A) with reaction
time. The coordination of the hydrovinylation product A
to the active species allows the isomerization with subse-
quent increase of the 2-phenyl-2-butene isomers (B and C).
The consecutive isomerization reaction may take place
with a kinetic resolution modifying the ee value as already
reported.29
In Table 4, the activity of the catalysts is expressed in terms
of TOF values, which also allow an evaluation of the stability
of the active species, whereby a decrease in TOF values over a
long reaction time (60 vs 360 min) indicates the decomposi-
tion of the active species. All the precursors with actual
monodentate ligands were active to a different extent, but
those with ligands (7c, 7d) that can act as hemilabile present
very low activity (entry 14, TOF=40 and entry 17, TOF=0
The cationic precursors with a dimethylcyclohexyldiami-
no backbone, 8b and 8e, yielded low activity (entries 21-24).
These complexes undergo the symmetrization process men-
tioned above, lowering the concentration of the active
species and leading to low TOF values. Moreover, the
bisphosphorous-donor cationic complexes formed are not
active in the hydrovinylation reaction, as reported.30f
Table 4 shows that precursors containing ligands with a
dimethylbinaphthyldiamino backbone (9b, 9e) are more
active and selective toward 3-phenyl-1-butene (A) than those
with a dibenzylcyclohexyldiamino one (7a, 7b) (entries 1-13
vs 25-30), and the best activities were always achieved when
the third substituent was bornyloxy (b).
Related to enantioselectivity, once again, very good results
were obtained with diazaphosphepine ligands 9b-(R,Sal)
(ee=90% (R)) and 9b-(R,Ral) (ee=80% (R)), and as the ee
(41) Jolly, P. W. In Applied Homogeneous Catalysis with Organome-
tallics Compounds, Vol. 3; Cornils, B., Herrrmann, W. A., Eds.; VCH:
New York, 2002; p 1164.
(42) Nandi, M.; Jin, J.; Rajanbabu, T. V. J. Am. Chem. Soc. 1999,
122, 9899.
(43) Pregosin, P. S. Chem. Commun. 2008, 4875.

124 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
values show, a mismatch effect was observed depending on
the chirality of the third bornyloxy group substituent. The
enantioselectivity of the process is determined by the amine
backbone chirality in diazaphosphepine ligands (entries 25-31),
while the third alkoxy substituent chirality determines the
configuration of the major enantiomer when the ligand
contains the cyclohexyl backbone. For the 7b-(R,R,Sal)
ligand, ee = 25% (R), whereas for 7b-(R,R,Ral) ee = 28%
(S) (entries 9 vs 12). A decrease in the selectivity toward
codimer A was observed because of the secondary isomer-
ization process when the reaction time was 360 min, but with
only diazaphospholidine ligands a kinetic resolution con-
trolled by the backbone chirality was observed (entries 9-13
with 7b ligands). Moreover, less isomerization was observed
with 9 ligands, presumably because the bulky dimethylbi-
naphthyldiamino fragment hinders the coordination of the
3-phenyl-1-butene product. In order to compare the activity
of precursors containing similar backbones but with differ-
ent phosphorus substituent groups, we ran a hydrovinylation
reaction with a cationic complex containing the Binepine
ligand (three P-C bonds). Moderate activities and enantios-
electivities were achieved, suggesting that the best catalytic
precursors are obtained when the ligand contains P-O/P-N
bonds (entries 32 and 33).
The results obtained with the palladium(II) precursor
containing the 9b-(R,Sal) diamidophosphite ligand, with a
dimethylbinaphthyldiamino backbone and chiral bornyloxy
as a third substituent, are the best that have been reported
to date in the literature for the asymmetric codimerization
of styrene and ethylene at moderate conditions (15 °C and
15 bar ethylene pressure). It can be argued that the good
enantioselectivity comes from a secondary interaction be-
tween the metal center and the arene electrons from the
atropisomeric chiral auxiliary, as reported by Pregosin.43
This interaction might lead to an active species with better
discrimination in the coordination step of the prochiral
faces of the styrene, improving the enantiosectivity of the
reaction.
evaluate a possible symmetrization process. The cationic
compounds were used as catalyst precursors in the hydro-
vinylation of styrene. Those without hemilabile ligands were
active and selective toward the codimerization of styrene and
ethylene. Very good activity (TOF=595) and enantioselec-
tivity (ee = 90%) were obtained with the precursor that contained
the 9b-(R,Sal) ligand, with the dimethylbinaphthyldiamino
backbone and the bornyloxy group as a third substituent in
the phosphorus atom. Thus, as stated by Leitner,28a it seems
that an efficient ligand for asymmetric hydrovinylation should
possess a P-N bond and contain more than one element
of chirality, one of them preferably being an atropoiso-
meric unit.
Experimental Section
General Data. All compounds were prepared under a pur-
ified nitrogen atmosphere using standard Schlenk and vacuum-
line techniques. The solvents were purified by standard pro-
cedures and distilled under nitrogen; the reagents were ob-
tained from commercial sources and used without further
purification. The diamines (R,R)-1,2-diaminocyclohexane,
N,N0-dimethyl-1,2-diaminocyclohexane (2-(R,R)), and (R)-
N,N0-dimethyl-1,10-binaphthyl-2,20-diamine (3-(R)) were used
as supplied from Aldrich. N,N0-Dibenzyl-1,2-diaminocyclo-
hexane (1-(S,S), 1-(R,R)),44 the diamidophosphites 7f-(RR)14a
and 9e-(R),13 and the dimeric palladium complex [Pd(η3-2-
45
CH3C3H4)(μ-Cl)]2 were prepared as previously described.
The 1H, 13C (1H, 13C, standard SiMe4), and 31P (31P, standard
H3PO4) NMR spectra were recorded on either a Bruker DRX
250 (31P, 101 MHz), Varian Mercury400 MHz (13C,100MHz), or
Varian Mercury 500 MHz (13C, 125 MHz) spectrometer in
CDCl3 unless otherwise stated. Chemical shifts in ppm were
reported downfield from standards. The two-dimensional
experiments were carried out in a Varian Mercury 400 MHz
or a Varian Mercury 500 MHz instrument at 298 K with
mixing time of 500 ms for NOESY experiments. FAB mass
chromatograms were obtained on a LC7MSD-TOF (Agilent
Technologies) instrument. The GC analyses were performed
on an Agilent Technologies 6890N gas chromatograph (30 m
HP-5 column) with a FID detector. Enantiomeric excesses
were determined by GC on a Hewlett-Packard 5890 Series II
gas chromatograph (30 m Chiraldex DM column) with a FID
detector. Elemental analyses were carried out by the Serveis
Conclusions
We have developed a new family (12 members) of chiral
phosphorus ligands of general structure I (Figure 1) for use in
enantioselective catalysis. The new diamidophosphite li-
gands with substituted diaminobinaphthyl and diaminocy-
clohexyl backbones possess a highly modular structure that
is well suited to the synthesis of a library. The preparation
of the selenide derivatives and examination of the JPSe
coupling constants provide a simple technique for a rough
estimation of the σ-donor ability of these ligands.
ꢀ
Cientificotecnics of the Universitat Rovira i Virgili in an Eager
1108 microanalyzer. Optical rotations were measured on a
Perkin-Elmer 241 MC spectropolarimeter at 25 °C.
Synthesis of Diamidophospite Ligands. 7a-(R,R,Ral), 7a-(S,S,Sal),
7a-(R,R,Sal), and 7a-(S,S,Ral) were prepared following the
method described in the literature for similar ligands14a with
some modifications. (R,R)-N,N0-Dibenzyl-1,2-diaminecyclohexane
or (S,S)-N,N0-dibenzyl-1,2-diaminecyclohexane (1.17 g, 3.98 mmol)
and NEt3 (1.66 mL, 11.95 mmol) were dissolved in 8 mL of
toluene. PCl3 (0.35 mL, 3.98 mmol) dissolved in 5 mL of
toluene was added dropwise at 0 °C. The mixture was stirred
for 3 h at 0 °C, and (S)-1-phenylethanol or (R)-1-phenyletha-
nol (1.01 mL, 3.98 mmol) was added at the same temperature.
After 2 h stirring hexane (5 mL) was added and the white
precipitate of triethylamine hydrochloride was filtered off. The
solvent was removed under vacuum, and a colorless oil was
obtained and used without purification. MS/ESI (þ) (m/z):
445.2403 [(MH)]þ. 7a-(R,R,Ral): yield 1.35 g (76%); [R]298
(c 1.04, CH2Cl2)=-18.98. 7a-(S,S,Sal): yield: 1.05 g (60%);
[R]298 (c 1.0, CH2Cl2)=þ4.11. 7a-(R,R,Ral) and 7a-(S,S,Sal):
31P NMR (toluene, 101 MHz) [δ/ppm] 135.2 (s); 1H NMR
(CDCl3, 400 MHz) [δ/ppm] 7.30-7.09 (om, 15H, Ar), 4.95 (dq,
1
We have prepared neutral allyl palladium complexes of
general formula [PdCl(η3-2-CH3C4H4)L]. Through NMR
spectroscopy of their solutions we have detected the presence
of two isomers, while with 2D NOESY experiments we have
observed their dynamic behavior; complexes with a cyclo-
hexyl scaffold showed the π-σ-π exchange, but those with
the binaphthyl backbone showed the two well-known move-
ments, namely, apparent π-allyl rotation and π-σ-π ex-
change, under the same conditions. The determination of the
X-ray structure of one complex, 11a-(S,S,Sal), confirmed the
expected configuration for all the stereogenic carbon atoms
of the ligand after the synthesis.
The cationic derivatives [Pd(η3-2-CH3C4H4)LS]BF4 were
prepared and monitored by NMR spectroscopy, in order to
(44) Tye, H.; Elred, C.; Wills, M. Tetrahedron Lett. 2002, 43, 155.
(45) Dent, W. T.; Long, R.; Wilkinson, A. J. J. Chem. Soc. 1964, 1585.

Article
Organometallics, Vol. 30, No. 1, 2011 125
JHP =8.8, JHH =6.4, 1H, OCH), 4.17-4.04 (om, 2H, CH2),
3.96 (dd, JHH =15.6, JHP =12, 1H, CH2), 3.48 (dd, JHH =
CH2Cl2) = -46.14; 31P NMR (toluene, 101 MHz) [δ/ppm]
137.1 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 7.30-7.18 (om,
10H, Ar), 5.80 (m, 1H, CH), 5.17 (d, Jtrans = 17.9, 1H, CH2),
5.04 (d, Jcis = 10.4, 1H, CH2), 4.35-3.82 (om, 6H, 4CH2,
2OCH2), 3.07 (m, CH), 2.51 (m, CH), 1.78-1.54 (om, 4H, CH2),
1.14-0.84 (om, 4H, CH2). No 13C NMR data because of fast
oxidation.
15.2, JHP = 9.6, 1H, CH2), 2.91 (m, CH), 2.44 (m, CH),
1.77-1.50 (om, 4H, CH2), 1.36 (d, JHH = 6.4, 3H, CH3),
1.21-0.91 (om, 4H, CH2); 13C NMR (CDCl3, 100 MHz)
[δ/ppm] 128.74-125.48 (Ar), 71.74 (OCH), 67.33 (CH), 66.44
(CH), 50.23 (CH2), 48.27 (CH2), 30.45 (CH2), 30.22 (CH2),
26.61 (CH2), 26.06 (CH2), 24.29 (CH3). 7a-(R,R,Sal): yield 0.95 g
(60%); [R]298 (c 1.0, CH2Cl2)=-36.7. 7a-(S,S,Ral): yield 1.43 g
(81%); [R]298 (c 1.29, CH2Cl2) = þ21.88. 7a-(R,R,Sal) and
7a-(S,S,Ral): 31P NMR (toluene, 101 MHz) [δ/ppm] 140.7
(s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 7.31-7.09 (om,
15H, Ar), 4.86 (m, 1H, OCH), 4.23 (pt, JHH = JHP= 13.5,
8b-(R,R,Sal) was synthesized in a similar way to that described
for the preparation of 7a. Starting materials: diamine 2-(R,R)
(1 g, 7.0 mmol), NEt3 (7.82 mL, 56.3 mmol), PCl3 (0.61 mL,
7.0 mmol), (S)-1-borneol (1.08 g, 7.0 mmol). Yield: 1.78 g
(78%); MS/ESI (þ) (m/z) 325.2407 [(MH)]þ; [R]298 (c 1.0,
CH2Cl2) = -141.45; 31P NMR (toluene, 101 MHz) [δ/ppm]
1
1H, CH2), 4.17 (pt, JHH=JHP=13.5, 1H, CH2), 3.82 (pt, JHH
=
144.0 (s); H NMR (CDCl3, 400 MHz) [δ/ppm] 4.02 (m, 1H,
JHP = 14.8, 1H, CH2), 3.52 (dd, JHH = 15.2, JHP = 10.4, 1H,
CH2), 2.99 (m, CH), 2.46 (m, CH), 1.31 (d, JHH = 6.4, 3H, CH3),
1.77-0.81 (om, 8H, CH2); 13C NMR (CDCl3, 100 MHz) [δ/ppm]
129.15-125.31 (15H Ar), 72.55 (OCH), 67.55 (CH), 66.23 (CH),
50.37 (CH2), 48.25 (CH2), 30.45 (CH2), 30.29 (CH2), 26.19(CH3),
24.60 (CH2), 24.38 (CH2).
OCH), 2.63 (m, 1H, CH), 2.60 (d, JHP = 13.2, 3H, NCH3), 2.42
(d, JHP = 14, 3H, NCH3), 2.29 (m, 1H, CH), 2.11 (m, 1H, CH2),
2.01-1.85 (om, 3H, CH2), 1.75-1.70 (om, 2H, CH2), 1.60 (m,
1H, CH2), 1.50 (t, JHH = 4.8, 1H, CH), 1.2-0.95 (om, 6H, 4CH2
(Cy), 2CH2), 0.89 (dd, JHH = 13.2, JHP = 3.2, 1H, CH2), 0.78
(bs, 3H, CH3) 0.77 (bs, 3H, CH3), 0.74 (bs, 3H, CH3); 13C NMR
(CDCl3, 100 MHz) [δ/ppm] 79.86 (OCH), 69.55 (CH), 66.83
(CH), 45.07 (CH), 38.85 (CH2), 33.29 (NCH3), 30.45 (NCH3),
29.88 (CH2), 29.25 (CH2), 28.19 (CH2), 29.25 (CH2), 24.28
(2CH2), 20.28 (CH3), 19.95 (CH3), 13.61 (CH3).
7b-(R,R,Ral) and 7b-(R,R,Sal) were synthesized in a similar
way to that described for the preparation of 7a. Starting materials:
diamine 1-(R,R) (2.5 g, 8.5 mmol), NEt3 (3.54 mL, 25.5 mmol),
PCl3 (0.73 mL, 8.5 mmol), (R)-1-borneol or (S)-1-borneol
(1.31 mmol, 8.5 mmol). MS/ESI (m/z): 477.3025 [(MH)]þ.
7b-(R,R,Ral): yield 2.85 g (70%); [R]298 (c 1.0, CH2Cl2) =
8e-(R,R) was synthesized in a similar way to that described for
the preparation of 7a. Starting materials: diamine 2-(R,R) (1 g,
7.0 mmol), NEt3 (7.83 mL, 56.3 mmol), PCl3 (0.61 mL, 7 mmol),
methanol (0.37 mL, 9.2 mmol). Yield: 0.73 g (52%); MS/ESI (þ)
1
-30.45; 31P NMR (toluene, 101 MHz) [δ/ppm] 135.9 (s); H
NMR (CDCl3, 400 MHz) [δ/ppm] 7.41-7.08 (om, 10H, Ar),
(m/z) 203.0882 [(MH)]þ; [R]298 (c 1.00, CH2Cl2)=-126.70; 31
P
4.28 (dd, JHH =15.3, JHP =11.7, 1H, CH2), 4.20 (t, JHH
J
=
=
NMR (toluene, 101 MHz) [δ/ppm] 136.0 (s); 1H NMR (CDCl3,
400 MHz) δ 3.36 (d, JHP = 9.6, 3H, OCH3), 2.65 (m, 1H, CH),
2.61 (d, JHP=14, 3H, NCH3), 2.48 (d, JHP=14, 3H, NCH3),
2.24 (m, 1H, CH), 2.00-1.82 (om, 2H, CH2), 1.80-1.64
(om, 2H, CH2), 1.22-0.5 (om, 4H, CH2); 13C NMR (CDCl3,
100 MHz) [δ/ppm] 68.65 (CH), 65.58 (CH), 50.75 (OCH3), 32.55
(NCH3), 29.55 (NCH3), 28.56 (2CH2), 23.53 (2CH2).
HP =14.1, 2H, CH2), 4.09 (m, 1H, OCH), 3.73 (dd, JHH
15.3, JHP =8.4, 1H, CH2), 2.92 (m, 1H, CH), 2.46 (m, CH),
2.07-1.90 (m, 2H, CH2), 1.75-1.50 (om, 6H, 5 CH2, 1 CH),
1.24-0.92 (om, 6H, CH2), 0.83-0.73 (om, 10H, 1 CH2, 9
CH3); 13C NMR (CDCl3, 100 MHz) [δ/ppm] 128.72-126.87
(Ar), 77.60 (OCH), 67.22 (CH), 66.56 (CH), 50.05 (CH2), 48.77
(CH2), 45.25 (CH), 38.24 (CH2), 30.67 (CH2), 30.29 (CH2),
30.25 (CH2), 28.36 (CH2), 26.78 (CH2), 24.47 (CH2), 20.17
(CH3), 19.00 (CH3), 13.82 (CH3). 7b-(R,R,Sal): yield 3.36 g
(83%); [R]298 (c 1.0, CH2Cl2) = -22.29; 31P NMR (toluene,
101 MHz) [δ/ppm] 142.4 (s); 1H NMR (CDCl3, 400 MHz)
9b-(R,Sal). (R)-N,N0-Dimethyl-1,10-binaphthyl-2,20-diamine
(3-(R)) (0.5 g, 1.6 mmol) and freshly dried and distilled NEt3
(1.78 mL, 12.8 mmol) were dissolved in 20 mL of toluene. PCl3
(0.14 mL, 1.6 mmol) dissolved in 10 mL of toluene was added
dropwise at 0 °C and stirred for 2 h. (S)-1-Borneol (0.25 g,
1.6 mmol) was added and stirred for 10 h at 0 °C. The white
precipitate of triethylamine hydrochloride was filtered off after
hexane addition (5 mL). The solvent was removed under re-
duced pressure, and a yellow solid was obtained. Yield: 0.65 g
(83%); MS/ESI (þ) (m/z) 495.2558 [(MH)]þ; [R]298 (c 1.0,
CH2Cl2) = -51.5; 31P NMR (toluene, 101 MHz) [δ/ppm]
177.6 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 7.86-6.68
(om, 12H, Ar), 4.27 (m, 1H, HCO), 2.91 (d, JHP = 13.6, 3H,
NCH3), 2.89 (d, JHP = 9.6, 3H, NCH3), 2.21 (m, 1H, CH2), 1.82
(m, 1H, CH2), 1.71-1.54 (om, 2H, 1CH2, 1CH), 1.22-1.12 (om,
2H, CH2), 0.81-0.77 (om, 10H, 1CH2, 9CH3); 13C NMR,
no data because of fast oxidation.
9b-(R,Ral). (R)-N,N0-Dimethyl-1,10-binaphthyl-2,20-diamine
(3-(R)) (0.5 g, 1.6 mmol) and freshly dried and distilled NEt3
(1.78 mL, 12.8 mmol) were dissolved in 10 mL of toluene. PCl3
(0.28 mL, 3.2 mmol) dissolved in 5 mL of toluene was added
dropwise at 0 °C and stirred for 2 h. The mixture was allowed to
warm to room temperature and stirred overnight. After eva-
poration to dryness the solid was dissolved in 10 mL of toluene,
and NEt3 (24 mmol) and (R)-1-borneol (1.6 mmol) were added.
The mixture was stirred for 2 h at 0 °C and 20 h at room
temperature. After 20 min at 4 °C the formation of a white
precipitate was observed and filtered off. The evaporation of the
solvent under reduced pressure led to the formation of a yellow
solid. Yield: 0.65 g (83%); MS/ESI (þ) (m/z) 495.2554 [(MH)]þ;
[R]298 (c 1.0, CH2Cl2)=-37.37; 31P NMR (toluene, 101 MHz)
[δ/ppm] 178.6 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm]
[δ/ppm] 7.36-7.13 (m, 10H, Ar), 4.34 (dd, JHH = 16, JHP
=
13.6, 1H, CH2), 4.11 (dd, JHH=15, JHP=12, 2H, CH2), 3.98
(m, 1H, OCH), 3.76 (dd, JHH=15.2, JHP=10.8, 1H, CH2), 2.95
(m, 1H, CH), 2.47 (m, 1H, CH), 2.1 (m, 1H, CH2), 2.0 (m, 1H,
CH2), 1.72-1.48 (om, 6H, 5CH2, 1CH), 1.24-0.77 (om, 7H,
CH2), 0.75 (s, 3H, CH3), 0.72 (s, 3H, CH3), 0.65 (s, 3H, CH3);
13C NMR (CDCl3, 100 MHz) [δ/ppm] 128,5-125.0 (Ar), 79.0
(OCH), 67.72 (CH), 66.62 (CH), 50.82 (CH2), 48.75 (CH2),
45.0 (CH), 38.87 (CH2), 30.92 (CH2), 30.24 (CH2), 28.44
(CH2), 26.77 (CH2), 24.42 (2 CH2), 20.14 (CH3), 18.90
(CH3), 13.63 (CH3).
7c-(R,R,Sal) was synthesized in a similar way to that described
for the preparation of 7a. Starting materials: diamine 1-(R,R)
(1 g, 3.4 mmol), NEt3 (2.42 mL, 10.2 mmol), PCl3 (0.20 mL, 3.4
mmol), methyl-(S)-lactate (0.32 mL, 3.4 mmol). Yield: 1.02 g
(70%). MS/ESI (þ) (m/z): 427.2151 [(MH)]þ; [R]298 (c 1.0,
CH2Cl2) = -46.55; 31P NMR (toluene, 101 MHz) [δ/ppm]
140.4 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 7.38-7.18 (om,
10H, Ar), 4.40-4.15 (om, 3H, 2CH2, 1CH), 4.0-3.80 (om, 2H,
CH2), 3.72 (s, 3H, CH3), 3.07 (m, 1H, CH), 2.51 (m, 1H, CH),
1.90-1.54 (om, 4H, CH2), 1.30 (d, JHH = 7.2, 3H, CH3),
1.22-0.85 (om, 4H, CH2); 13C NMR (CDCl3, 100 MHz)
[δ/ppm] 129.03-126.77 (Ar), 68.80 (CH), 66.88 (CH), 66.17
(CH), 52.59 (CH3), 49.91 (CH2), 47.97 (CH2), 29.88 (CH2),
29.18 (CH2), 24.38 (CH2), 24.20 (CH2), 20.45 (CH3).
7d-(R,R) was synthesized in a similar way to that described
for the preparation of 7a. Starting materials: diamine 1-(R,R)
(1.2 g, 4.15 mmol), NEt3 (1.73 mL, 12.46 mmol), PCl3 (0.36 mL,
4.15 mmol), allylic alcohol (0.35 mL, 4.15 mmol). Yield: 1.11 g
(78%); MS/ESI (þ) (m/z) 381.2098 [(MH)]þ; [R]298 (c 1.0,
7.84-6.99 (om, 12H, Ar), 4.32 (m, 1H, HCO), 2.88 (d, JHP =
12, 3H, NCH3), 2.81 (d, JHP = 8, 3H, NCH3), 2.17 (m, 1H,

126 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
CH2), 1.86 (m, 1H, CH2), 1.63-1.49 (om, 2H, 1CH2, 1CH),
1.20-1.00 (om, 3H, CH2), 0.91 (s, 3H, CH3), 0.82 (s, 3H, CH3),
0.80 (s, 3H, CH3); 13C NMR (CDCl3, 100 MHz) [δ/ppm]
128.24-121.54 (Ar), 81.78 (HCO), 44.91 (CH), 38.36 (NCH3),
35.20 (NCH3), 37.56 (CH2), 28.12 (CH2), 26.68 (CH2), 20.12
(CH3), 18.93 (CH3), 13.68 (CH3).
Selenides. General procedure: 0.15 mmol of ligand dissolved
in 2 mL of toluene in the presence of 1.2 mmol of selenium
powder was stirred for 2 h. Then the reaction mixture was
filtered through Celite. The compounds were characterized by
31P NMR (101 MHz) in toluene solution.
(dd, JHH = 16 JHP = 14, 1H, CH2), 4.79 (dd, JHH = 16, JHP
14, 1H, CH2), 4.70 (m, 1H, HCO) 4.60-4.30 (om, 7H, 6CH2,
1HCO), 4.04 (dd, JHH = 15.6 JHP = 10, 1H, CH2), 3.87 (dd,
JHH = 16.4, JHP = 5.6, 1H, CH2), 3.48 (bs, 1H, CH2), 3.48
(d, JHP = 14, 1H, CH2), 3.35 (bs, 1H, CH2), 3.14 (d, JHP = 14.8,
1H, CH2), 3.18-2.94 (om, 4H, CH), 2.56 (m, 1H, CH2),
2.24-2.18 (om, 3H, CH2), 1.98-1.54 (om, 21H, 2CH, 13CH2,
6CH3), 1.3-0.98 (om, 31H, 13CH2, 18CH3). Anal. Calcd for
C34H48ClN2OPPd (%): C, 60.63; H, 7.18; N, 4.16. Found:
C, 60.92; H, 7.36; N, 4.38. 11b-(R,R,Sal): 2.00 g, yield 75%;
=
1
31P NMR (toluene, 101 MHz) [δ/ppm] 133.5 (s), 131.2 (s); H
Synthesis of Palladium(II) Complexes. [PdCl2L2] (10).PdCl2(cod)
(0.29 g, 1.05 mmol) and 1 g (2.1 mmol) of ligand 7b-(R,R,Sal) were
dissolved in 20 mL of CH2Cl2 at room temperature. After 2 h
stirring, the resulting yellow solution was concentrated under
vacuum and 10 mL of ether was added. The yellow precipitate
was filtered and dried. Yield: 0.98 g (83%); 31P NMR (toluene,
101 MHz) [δ/ppm] 91.84 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm]
7.63-7.09 (om, 20H, Ar), 4.96 (dt, JHH = 16, JHP = 6.8, 2H, CH2),
4.85 (dt, JHH = 16, JHP = 6.4, 2H, CH2), 4.58-4.81 (m, 2H, OCH),
NMR (CDCl3, 400 MHz) [δ/ppm] 7.62-7.18 (m, 20H, Ar), 4.98
(m, 1H, HCO), 4.82 (m, 2H, CH2), 4.6-4.3 (om, 7H, 6CH2,
1HCO), 4.05 (dd, JHH = 16, JHP = 8.4, 1H, CH2), 3.70 (dd,
JHH = 16.4, JHP = 5.4, 1H, CH2), 3.44 (d, JHP = 14, 1H, CH2),
3.41 (bs, 1H, CH2), 3.37 (bs, 1H, CH2), 3.19 (d, JHP = 14, 1H,
CH2), 3.10 (m, 2H, CH), 2.99 (m, 2H, CH), 2.39 (bs, 1H, CH2),
2.28 (bs, 1H, CH2), 2.25-1.41 (om, 22H, 14CH2, 2CH, 6CH3),
1.38-0.90 (om, 13H, CH2), 0.91-0.82 (om, 19H, 1CH2,
18CH3). Anal. Calcd for C34H48ClN2OPPd (%): C, 60.63; H,
7.18; N, 4.16. Found: C, 59.58; H, 7.23; N, 3.89.
4.40 (dt, JHH = 16, JHP = 6, 2H, CH2), 4.08 (dt, JHH = 16.4, JHP
=
2.4, 2H, CH2), 3.20 (m, 2H, CH), 2.98 (m, 2H, CH), 2.27 (m, 1H,
CH2), 2.08 (m, 1H, CH2), 1.76-0.86 (om, 28H, 26CH2, 2CH), 0.85
(s, 6H, CH3), 0.80 (s, 6H, CH3), 0.79 (s, 6H, CH3). Anal. Calcd for
C60H82Cl2N4O2P2Pd (%): C, 63.74; H, 7.31; N, 4.96. Found: C,
63.53; H, 7.59; N, 4.95.
11c-(R,R,Sal) was synthesized in a similar way to that used
for 11b. Starting materials: 0.48 g (1.2 mmol) of [Pd(η3-2-
CH3C3H4)(μ-Cl)]2and 1.02 g (2.38 mmol) of ligand 7c-(R,R,Sal).
Yield: 1.07 g (72%); 31P NMR (toluene, 101 MHz) [δ/ppm]
134.3 (s), 133.9 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm]
7.55-7.15 (m, 20H, Ar), 5.09 (dq, JHP = 12.4 JHH = 6.4, 1H,
[PdCl(η3-2-CH3C3H4)L] (11-14). The complexes were ob-
tained by similar procedures described in the literature.30
For 11a-(R,R,Ral), 11a-(S,S,Sal), 11a-(R,R,Sal), and 11a-(S,S,
Ral), 0.22 g (0.6 mmol) of [Pd(η3-2-CH3C3H4)(μ-Cl)]2 was
dissolved in 5 mL of toluene and 0.5 g (1.1 mmol) of ligand 7a
dissolved in 5 mL of CH2Cl2 was added. The mixture was stirred
at 0 °C for 2 h, and the solvent removed under reduced pressure.
Addition of ether (10 mL) led to a brown solid. 11a-(R,R,Ral):
yield 0.48 g (67%). 11a-(S,S,Sal): yield 0.43 g (60%); 31P NMR
(toluene, 101 MHz) [δ/ppm] 126.7 (s), 126.2 (s); 1H NMR
(CDCl3, 400 MHz) [δ/ppm] 7.50-7.03 (m, 30H, Ar), 5.27
(m, 1H, OCH), 5.21 (m, 1H, OCH), 4.95 (dd, JHH = 15.2,
CH), 4.94 (dq, JHP = 12.4, JHH = 6.4, 1H, CH), 4.74 (pt, JHP
=
JHH = 16.4, 2H, CH2), 4.61-4.31 (om, 6H, CH2), 4.19
(dd, JHP = 16, JHH = 9.6, 1H, CH2), 4.04 (dd, JHP = 16.4,
J
HH = 6, 1H, CH2), 3.63 (s, 3H, CH3), 3.59 (s, 3H, CH3), 3.52
(bs, 2H, CH2), 3.44 (d, JHP = 14, 1H, CH2), 3.25 (d, JHP = 14.4,
1H, CH2), 3.11-3.03 (m, 4H, CH), 2.52 (bs, 1H, CH2), 2.31
(bs, CH2), 1.83-1.50 (om, 14H, 6CH3, 8CH2), 1.38 (d, JHH
=
6.8, 6H, CH3), 1.25-1.04 (om, 8H, CH2). Anal. Calcd for
C28H38ClN2O3PPd (%): C, 55.36; H, 6.31; N, 4.61. Found: C,
53.11; H, 6.44; N, 4.57.
11d-(R,R) was synthesized in a similar way to that used
for 11b. Starting materials: 0.42 g (1.05 mmol) of [Pd(η3-2-
CH3C3H4)(μ-Cl)]2 and 0.82 g (2.16 mmol) of ligand 7d-(R,R).
Yield: 0.27 g (44%); 31P NMR (toluene, 101 MHz) [δ/ppm]
129.0 (s), 128.6 (s); 1H NMR (CDCl3, 400 MHz) [δ/ppm]
7.48-7.13 (om, 20H, Ar), 5.13-5.05 (om, 4H, CH2), 4.81-
4.66 (om, 2H, CH2), 4.44-4.38 (om, 8H, CH2), 3.32 (m, 1H,
CH2), 3.17-3.14 (om, 3H, 2CH, 1CH2), 3.01-2.98 (om, 4H,
2CH, 2CH2), 2.18 (bs, 2H, CH2), 2.04 (bs, 2H, CH2), 1.76 (s, 3H,
CH3), 1.60 (s, 3H, CH3), 1.86-1.08 (om, 16H, CH2); MS/ESI (þ)
(m/z) 541.1601 [(M - Cl)]þ. Anal. Calcd for C27H36ClN2OPPd
(%): C, 56.16; H, 6.28; N, 4.86. Found: C, 56.35; H, 6.69;
N, 5.10.
JHP = 12, 1H, CH2), 4.83 (dd, JHH=15.2, JHP=12.4, 1H, CH2),
4.34-4.21 (om, 3H, CH2), 4.13 (pt, JHH=JHP=16, 1H, CH2),
3.80 (m, 1H, CH2), 3.54 (dd, JHH=16 JHP = 12, 1H, CH2), 3.42
(d, JHP = 14.4, 1H, CH2), 3.37 (bs, 1H, CH2), 3.25 (bs, 1H,
CH2), 3.09 (m, 2H, CH), 2.94 (d, JHP = 14.4, 1H, CH2), 2.92
(m, 1H, CH2), 2.77 (m, 2H, CH), 2.52 (dd, JHH = 16.4
JHP = 6.4, 1H, CH2), 2.43 (bs, 1H, CH2), 2.08 (bs, 1H, CH2),
1.86 (s, 3H, CH3), 1.47 (s, 3H, CH3), 1.14 (d, JHH = 6.4, 3H,
CH3), 1.01 (d, JHH = 6.4, 3H, CH3), 1.63-0.71 (om, 16H, CH2).
Anal. Calcd for C32H40ClN2OPPd (%): C, 59.91; H, 6.28; N,
4.37. Found: C, 59.63; H, 6.71; N, 4.02. 11a-(R,R,Sal): yield 0.24
g (34%). 11a-(S,S,Ral): yield 0.17 g (24%); 31P NMR (toluene,
1
101 MHz) [δ/ppm] 130.7 (s), 130.0 (s); H NMR (CDCl3, 400
11f-(R,R) was synthesized in a similar way to that used for 11b
and precipitated in ether. Starting materials: 0.41 g (1.05 mmol)
of [Pd(η3-2-CH3C3H4)(μ-Cl)]2 and 0.84 g (2.09 mmol) of ligand
7f-(R,R). Yield: 0.31 g (51%); 31P NMR (toluene, 101 MHz)
[δ/ppm] 120.0 (s), 118.2 (s); 1H NMR (CDCl3, 400 MHz)
[δ/ppm] 7.66-7.13 (om, 30H, Ar), 4.80 (pq, JHP = JHH = 15.6,
2H, CH2), 4.52-5.37 (om, 4H, CH2), 4.29 (pt, JHP = JHH = 14,
MHz) [δ/ppm] 7.44-6.96 (m, 30H, Ar), 5.64 (m, 1H, CH), 5.52
(m, 1H, CH), 4.65-4.55 (om, 2H, CH2), 4.42-4.20 (om, 6H,
CH2), 3.79 (dd, JHH = 16.0 JHP = 8, 1H, CH2), 3.70 (dd, JHH =
16.8 JHP = 5.6, 1H, CH2), 3.32 (d, JHP = 14.0, 1H, CH2), 3.32
(bs, 1H, CH2), 3.24 (bs, 1H, CH2), 3.17 (d, JHP = 14.0, 1H,
CH2), 3.08-2.94 (om, 4H, CH), 2.21 (bs, 2H, CH2), 1.72 (s, 3H,
CH3), 1.66 (s, 3H, CH3), 1.63-1.45 (om, 8H, CH2), 1.45
(d, JHH=6.4, 6H, CH3), 1.18-0.94 (om, 8H, CH2). Anal. Calcd
for C32H40ClN2OPPd (%): C, 59.91; H, 6.28; N, 4.37. Found: C,
59.63; H, 6.71; N, 4.02.
1H, CH2), 4.19 (pt, JHP = JHH = 14, 1H, CH2), 3.71 (dd, JHH
15.2 JHH = 9.6, 1H, CH2), 3.47 (m, 1H, CH2), 3.35 (d, JHP
=
=
11.6, 1H, CH2), 3.31 (d, JHP = 12, 1H, CH2), 3.19 (m, 1H, CH),
3.06 (m, 1H, CH), 2.94 (bs, 1H, CH2), 2.86 (bs, 1H, CH2), 2.81
(m, 1H, CH), 2.72 (m, 1H, CH), 2.10 (bs, 1H, CH2), 2.00 (bs, 1H,
CH2), 1.78 (bs, 6H, CH3), 1.73-1.08 (om, 16H, CH2); MS/ESI (þ)
(m/z) 561.1726 [(M - Cl)]þ. Anal. Calcd for C30H36ClN2PPd
(%): C, 60.31; H, 6.07; N, 4.69. Found: C, 57.26; H, 5.77; N,
4.12.
12b-(R,R,Sal) was synthesized in a similar way to that used
for 11b Starting materials: 0.75 g (1.9 mmol) of [Pd(η3-2-
CH3C3H4)(μ-Cl)]2 and 1.24 g (3.8 mmol) of ligand 8b-(R,R,Sal).
Yield: 1.39 g (70%); 31P NMR (toluene, 101 MHz) [δ/ppm]
For 11b-(R,R,Ral) and 11b-(R,R,Sal), 1.90 g (4.0 mmol) of
ligand 7b dissolved in toluene (5 mL) was added to a solution of
0.78 g (2.0 mmol) of [Pd(η3-2-CH3C3H4)(μ-Cl)]2 in 5 mL of
CH2Cl2. The mixture was stirred at 0 °C for 2 h, and the solution
was dried under reduced pressure. The resulting orange residue
was washed with pentane (3 ꢀ 20 mL), giving the desired pro-
duct as an orange solid. 11b-(R,R,Ral): yield 1.86 g (70%);
1
31P NMR (toluene, 101 MHz) [δ/ppm] 130.0 (s), 129.9 (s); H
NMR (CDCl3, 400 MHz) [δ/ppm] 7.73-7.13 (m, 20H, Ar), 4.87

Article
Organometallics, Vol. 30, No. 1, 2011 127
128.5(s), 127.6(s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 4.36 (m,
2H, CH2), 4.11 (m, 2H, OCH), 3.54 (bs, 1H, CH2), 3.51 (bs, 1H,
CH2), 3.49 (d, JHP = 14.8, 1H, CH2), 3.38 (d, JHP = 14.8, 1H,
CH2), 2.81-2.59 (om, 18H, 12NCH3, 4CH, 2CH2), 2.24 (m, 2H,
CH2), 2.05-1.57 (om, 20H, 12CH2, 2CH, 6CH3), 1.35-0.95
(om, 14H, CH2), 0.89-0.86 (om, 18H, CH3). Anal. Calcd for
C22H40ClN2OPPd (%): C, 50.58; H, 7.73; N, 5.37. Found: C,
50.35; H, 7.74; N, 5.18.
Table 5. Crystal Data and Structure Refinement for 11a-(S,S,Sal)
empirical formula
fw
temperature
wavelength
cryst syst
C32H40ClN2OPPd
641.48
100(2) K
0.71073 A
monoclinic
P21
space group
unit cell dimens
a = 9.9272(2) A
b = 14.8544(5) A
c = 10.7168(3) A
1528.55(7) A3
2
R = 90°
β = 104.707(2)°
γ = 90°
12e-(R,R) was synthesized in a similar way to that used
for 11b. Starting materials: 1.04 g (2.7 mmol) of [Pd(η3-2-
CH3C3H4)(μ-Cl)]2 and 1.04 g (2.7 mmol) of ligand 8e-(R,R).
The complex was obtained as an orange oil. Yield: 0.78 g (30%);
volume
Z
density (calcd)
absorp coeff
F(000)
1.394 Mg/m3
0.774 mm-1
664
1
31P NMR (toluene, 101 MHz) [δ/ppm] 131.7(s), 131.3(s); H
NMR (CDCl3, 400 MHz) [δ/ppm] 4.41 (s, 1H, CH2), 4.39 (s, 1H,
CH2), 3.51-3.43 (om, 10H, 4CH2, 6OCH3), 2.90-2.50 (om,
18H, 2CH2, 4CH, 12NCH3), 2.07-1.73 (om, 14H, 6CH3,
8CH2), 1.39-0.90 (om, 8H, CH2); MS/ESI (þ) (m/z) 363.0817
[(M - Cl)]þ.
cryst size
θ range for data
collection
0.37 ꢀ 0.17 ꢀ 0.07 mm
1.96 to 30.03°
reflns collected
indep reflns
completeness to
θ = 30.03°
absorp correction
33 806
8899 [R(int) = 0.0399]
100.0%
13b-(R,Ral) and 13b-(R,Sal) were obtained in a similar way to
that used for 11b and precipitated in toluene/hexane. Starting
materials: 0.31 g (0.8 mmol) of [Pd(η3-2-CH3C3H4)(μ-Cl)]2 and
0.79 g (1.6 mmol) of ligand 8b. 13b-(R,Ral): yield 0.72 g (65%);
semiempirical from
equivalents
1
31P NMR (toluene, 101 MHz) [δ/ppm] 151.8 (s), 150.7 (s); H
max. and min transmn
refinement method
1.0000 and 0.8487
full-matrix least-squares
on F2
NMR (CDCl3, 400 MHz) [δ/ppm] 7.96-7.11 (om, 24H, Ar),
5.22 (m, 1H, OCH), 5.13 (m, 1H, OCH), 4.54 (dd, JHH = 9.2
data/restraints/params
goodness-of-fit on F2
final R indices
[I > 2σ(I)]
R indices (all data)
8899/1/358
1.032
J
HP = 3.3, 1H, CH2), 4.45 (dd, JHH = 9.6 JHP = 3.2, 1H, CH2),
3.60 (d, JHP = 12.4, 1H, CH2), 3.59 (d, JHP = 12.4, 1H, CH2),
3.47 (bs, CH2), 3.37 (bs, CH2), 3.17 (d, JHP = 13.2, 3H, NCH3),
3.10 (d, JHP = 13.6, 3H, NCH3), 3.08 (d, JHP = 9.2, 3H, NCH3),
3.07 (d, JHP = 8.8, 3H, NCH3), 2.65 (m, 1H, CH2), 2.54 (1H,
CH2), 2.46 (bs, 1H, CH2), 2.38 (bs, 1H, CH2), 1.92 (s, 3H, CH3),
1.82 (s, 3H, CH3), 1.81-1.60 (om, 5H, 2CH, 3CH2), 1.30-1.09
(om, 7H, 7CH2), 0.98 (s, 3H, CH3), 0.97 (s, 3H, CH3), 0.93
(s, 3H, CH3), 0.91 (s, 3H, CH3), 0.86 (s, 3H, CH3), 0.85 (s, 3H,
CH3); MS/ESI (þ) (m/z) 655.2068 [(M - Cl)]þ. Anal. Calcd for
C36H42ClN2OPPd (%): C, 62.52; H, 6.12; N, 4.05. Found: C,
63.31; H, 7.23; N, 3.92. 13b-(R,Sal): yield 0.39 g (36%); 31P
NMR (toluene, 101 MHz) [δ/ppm] 152.1 (s), 151.9 (s); 1H NMR
(CDCl3, 400 MHz) [δ/ppm] 7.9-7.0 (om, 24H, Ar), 5.32 (m, 2H,
OCH), 4.45 (d, JHP = 10.8, 1H, CH2), 4.39 (d, JHP = 9.2, 1H,
CH2), 3.53 (d, JHP = 10.0, 1H, CH2), 3.51 (d, JHP = 13.2, 1H,
CH2), 3.36 (s, CH2), 3.20 (s, CH2), 3.11 (d, JHP = 13.6, 3H,
NCH3), 3.05 (d, JHP = 9.6, 3H, NCH3), 3.03 (d, JHP = 14.4, 3H,
NCH3), 3.02 (d, JHP = 8.8, 3H, NCH3), 2.39 (s, 1H, CH2), 2.31
(s, 1H, CH2), 2.34-2.30 (om, 2H, CH2), 1.85 (s, 3H, CH3), 1.75
(s, 3H, CH3), 1.74-1.55 (om, 6H, 2CH, 4CH2), 1.23-1.02 (om,
6H, CH2), 0.89-0.76 (om, 18H, CH3). Anal. Calcd for
C36H42ClN2OPPd (%): C, 62.52; H, 6.12; N, 4.05. Found: C,
62.56; H, 6.79; N, 4.15.
R1 = 0.0293,
wR2 = 0.0609
R1 = 0.0333,
wR2 = 0.0629
0.000(15)
abs struct param
largest diff peak and hole 0.731 and -0.615 e A-3
[(M - Cl þ (CH3CN)]þ. Anal. Calcd for C32H28ClPPd (%): C,
65.66; H, 4.82. Found: C, 67.32; H, 5.18.
Structural Characterization. Suitable crystals of [PdCl(η3-2-
CH3C3H4)7a-(S,S,Sal)] (11a-(S,S,Sal)) for X-ray characterization
were mounted on a Bruker X8 Kappa APEXII diffractometer.
The data were collected at 100 K using graphite-monochromated
Mo KR radiation (λ = 0.71073 A). SHELXTL software was
used for solution and refinement.46 Absortion corrections were
made with the SADABS program.47 The structure was refined
by full-matrix least-squares on F2. The crystal structure has been
deposited at the Cambridge Crystallographic Data Centre with
the deposition number CCDC 795003.
Hydrovinylation Reaction. General Procedure. Hydrovinyla-
tion reactions were performed in a stainless-steel autoclave fitted
with an external jacket connected to an isobutanol bath, and the
temperature was controlled using a thermostat to (0.5 °C.
Internal temperature was controlled with a thermocouple, and
pressure was controlled with a transductor. The catalyst pre-
cursor solution was placed in the autoclave, which had pre-
viously been purged by succesive vacuum/nitrogen cycles and
thermostated at 15 °C. Ethylene was admitted until a pressure of
15 bar was reached. After the time indicated in Table 4 for each
reaction, the autoclave was slowly depressurized and NH4Cl
10% solution (10 mL) was added. The mixture was stirred 30
min in order to quench the catalyst. The CH2Cl2 layer was
decanted off, filtered through Celite and dried with Na2SO4. The
quantitative distribution of products and their enantiomeric
excess were determined by GC analysis.
13e-(R) was synthesized in a similar way to that used for 11b.
Starting materials: 0.11 g (0.3 mmol) of [Pd(η3-2-CH3C3H4)(μ-
Cl)]2 and 0.2 g (0.6 mmol) of ligand 9e-(R). Yield: 0.09 g (31%);
31P NMR (toluene, 101 MHz) [δ/ppm] 152.6 (s), 152.2 (s); H
1
NMR (CDCl3, 400 MHz) [δ/ppm] 7.91-6.98 (om, 24H, Ar),
4.42 (m, 2H, CH2), 3.51-3.49 (om, 8H, 6OCH3, 2CH2), 3.16
(d, JHP = 13.5, 6H, NCH3), 3.07-3.02 (om, 7H, 6NCH3,
1CH2), 2.92 (s, 1H, CH2), 2.31 (s, 1H, CH2), 2.26 (s, 1H,
CH2), 1.87 (s, 3H, CH3), 1.77(s, 3H, CH3). Anal. Calcd for
C27H28ClN2OPPd (%): C, 56.96; H, 5.68; N, 4.15. Found: C,
56.22; H, 5.68; N, 4.15.
14-(S) was synthesized in a similar way to that used for 11b.
Starting materials: 0.10 g (0.25 mmol) of [Pd(η3-2-CH3C3H4)-
(μ-Cl)]2 and 0.18 g (0.5 mmol) of ligand Binepine-(S). Yield: 0.1
g (38%); 31P NMR (toluene, 101 MHz) [δ/ppm] 40.32 (s), 39.79
(s); 1H NMR (CDCl3, 400 MHz) [δ/ppm] 8.07-7.01 (om, 34H,
Ar), 4.48 (m, 2H, CH2), 3.82 (d, JHH = 12.5, 1H, CH2), 3.70
(d, JHH = 12, 1H, CH2), 3.57 (bs, 1H, CH2), 3.48 (d, JHH = 10,
1H, CH2), 3.47 (d, JHH = 10.5, 1H, CH2), 3.39-3.19 (om, 6H,
CH2), 3.32 (bs, 1H, CH2), 2.83 (s, 1H, CH2), 2.46 (s, 1H, CH2),
2.01 (s, 3H, CH3), 1.78 (s, 3H, CH3); MS/ESI (þ) (m/z) 590.1229
(46) Sheldrick, G. M. SHELXS 97: A Computer Program for Crystal
€
Structure Determination; University of Gottingen: Germany, 1997. (b) Sheldrick,
G. M. SHELXS 97: A Computer Program for Crystal Structure Refinement;
€
University of Gottingen: Germany, 1997
(47) Sheldrick, G. M. SADABS: A Program for Empirical Absortion
€
Correction of Area Detector Data; University of Gottingen: Geramny, 1996.
Based on the method of Robert Blessing: Blessing, R. H. Acta Crystallogr. 1995,
A51, 33.

128 Organometallics, Vol. 30, No. 1, 2011
Ayora et al.
Preparation of Catalyst Precursor Solutions. To 0.03 mmol
of the appropiate neutral palladium complex (11-14) dis-
solved in 10 mL of CH2Cl2 were added 3.45 mL (30 mmol) of
styrene and 35.1 mg (0.18 mmol) of AgBF4. After stirring in
the dark at room temprature for 30 min and filtering off the
AgCl formed, the resulting solution was introduced in the
reactor.
61058) and by the Generalitat de Catalunya Departament
ꢁ
d’Universitat, Recerca i Societat de la Informacio
(2005SGR00287). The authors thank Prof. S. Gladiali
ꢀ
(Universita di Sassari) for a generous gift of Binepine
phosphine.
Supporting Information Available: NMR data for complexes
11-14. CIF file of complex 11a-(S,S,Sal). This material is
available free of charge via the Internet at http://pubs.acs.org.
Acknowledgment. This work was supported by the
Spanish Ministerio de Ciencia y Tecnologıa (CTQ2007-
´