Enantiomeric resolution and determination of the absolute configuration of dibenzophosphole 5-oxides

Article abstract of DOI:10.1016/S0957-4166(01)00339-1

The resolution of asymmetrically substituted dibenzophospholes via chromatographic separation of their cyclopalladium derivatives is described for the first time. The absolute configuration of the phosphorus atom was determined by X-ray crystallographic a

Full text of DOI:10.1016/S0957-4166(01)00339-1

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 12 (2001) 1987–1997
Enantiomeric resolution and determination of the absolute
configuration of dibenzophosphole 5-oxides
Ernesto Dura´n,a Esther Gordo,a Jaume Granell,b Merce` Font-Bard´ıa,c Xavier Solans,c
Dolores Velascoa and Francisco Lo´pez-Calahorraa,*
aDepartament de Qu´ımica Orga`nica, Universitat de Barcelona, Mart´ı i Franque`s, 1-11, E-08028 Barcelona, Spain
bDepartament de Qu´ımica Inorga`nica, Universitat de Barcelona, Diagonal 647, E-08028 Barcelona, Spain
cDepartament de Cristallografia i Dipo`sits Minerals, Universitat de Barcelona, Mart´ı i Franque`s s/n, E-08028 Barcelona, Spain
Received 14 June 2001; accepted 26 July 2001
Abstract—The resolution of asymmetrically substituted dibenzophospholes via chromatographic separation of their cyclopalla-
dium derivatives is described for the first time. The absolute configuration of the phosphorus atom was determined by X-ray
crystallographic analysis in one case. A general NMR criterion for the complete determination of the configuration of this group
of products is proposed. The enantiomeric excess of the resolved compounds was determined by NMR Eu(III) chemical
displacement experiments and by HPLC using a chiral stationary phase. © 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
(S,S)-1c and (R,S)-1c. The (SP) and (RP) diastereomers
could not be separated directly by physical methods, so
we had to find a new resolution method for this class of
compounds. The literature only gave a resolution
method of dibenzophospholes based on the synthesis of
diastereomeric amides from a pure enantiomeric amine
and racemic dibenzophospholes containing a carboxylic
acid function,5 and the separation was achieved by
recrystallization. However, the most attractive resolu-
tion method for our system needs to be generally
applicable for substituted dibenzophospholes and not
just to dibenzophospholes bearing a carboxylic acid
function. Therefore, we tried to find a new procedure,
of general applicability, to resolve optically active
dibenzophosphole 5-oxides.
Liquid crystals have been synthesized in recent years
mainly because successful applications of liquid crystals
have been developed, particularly in the area of electro-
optical displays.1 In this field, chiral nematic and smec-
tic liquid crystals became the most important source of
structures which have technological applications.
Our research group has worked on the synthesis of
some chiral molecules in order to generate chiral liquid
crystal macromolecular systems with ferroelectric prop-
erties (chiral smectic liquid crystals). It is known2 that
the introduction of a chiral group near the rigid core of
the mesogene is directly related to higher spontaneous
polarizability in these systems, and then with an
improvement of their ferroelectric physical properties.
As in previous studies on carbazole systems3,4 we syn-
thesized a similar structure derived from the diben-
zophosphole 1c with a stereogenic phosphorus atom in
the rigid planar core.
2. Results and discussion
Dimeric cyclopalladium compounds react readily with a
wide range of Lewis bases to afford monomeric com-
plexes of formulae [Pd(C-N)ClL] or [Pd(C-N)ClL2].
This simple reaction, using enantiomerically pure cyclo-
palladium dimers, is used for the resolution6–19 and
determination of the enantiomeric excess20–23 of Lewis
bases such as phosphines and amines. In addition,
phosphine oxides are reduced to phosphines with
trichlorosilane.24 With these facts in mind we used the
following procedure to resolve the new dibenzophosp-
hole 5-oxides: the first step was the trichlorosilane
reduction of these oxides (Scheme 1). Reaction of the
From this synthesis we obtained a 1:1 mixture of two
diastereomers, with different configuration on the phos-
phorus atom. The diastereomeric mixture of 1c showed
nematic liquid crystalline behaviour, and therefore chi-
ral mesophases could be seen for the pure diastereomers
* Corresponding author. Tel.: 0034 93 4021252; fax: 0034 93 3397878;
e-mail: flopez@qo.ub.es
0957-4166/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(01)00339-1

1988
E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
Scheme 1.
phosphines obtained with optically active cyclopalla-
dium compounds then gave a mixture of diastereomers
which were separated by column chromatography
(Scheme 2); the third step was to decoordinate the
dibenzophospholes by the reaction of the pure
diastereomers with 1,2-bis(diphenylphosphino)ethane
(dppe) and the last step of the resolution process was to
oxidize the enantiomerically pure ligands using hydro-
gen peroxide (Scheme 3).
tion of Lewis bases.6 Their efficiency has been related to
the locked asymmetric envelope conformation of the
metallacycle, due to the methyl substituent of the
stereogenic carbon adopting an axial disposition, which
avoids the unfavourable interaction with naphthylic
C(8%)H (see Scheme 2).25–30 In this study we used the
cyclopalladium derivative of (R)-(+)-1-(1-(naphthyl)-
ethylamine as the resolving agent.
The enantiomerically pure cyclopalladium binuclear
compound 3 was obtained from the optically active
amine as reported.31 Reaction of dimer 3 with the
dibenzophosphole 2a gave the mononuclear complex
Cyclopalladium complexes derived from 1-(1-naph-
thyl)ethylamine and N,N-dimethyl-1-(1-(naphthyl)-
ethylamine are the best resolving agents for the resolu-
Scheme 2. (Stereochemical descriptors refer only to the phosphorus atom.)
Scheme 3. (Stereochemical descriptors refer only to the phosphorus atom.)

E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
1989
the cis disposition of the phosphorus relative to the
metallated carbon atom. It should be noted that some
of the dibenzophosphole protons show an excellent
[PdCl(C-N)(P*)] 4a (see Scheme 2). The high-field shift
of the aromatic protons of the metallated naphthyl
group in 4a compared with the aromatic protons of the
phosphine indicates the cis disposition of the phospho-
rus atom relative to the metallated carbon atom.32 This
arrangement is usual in cyclopalladium compounds
containing phosphines: the destabilizing effect of two
soft ligands in mutual trans positions has been called
antisymbiosis,33–35 and recently the term transphobia
has been proposed to describe the difficulty of coordi-
nating mutually trans phosphine and aryl ligands in
palladium complexes.36,37
1
diastereomeric peak separation. The H NMR spectra
of (R,S)-4b and (R,R)-4b showed clear differences in
the aromatic protons C(4)H and C(6)H, the nearest to
the phosphorus atom in the dibenzophosphole ring (see
Scheme 1). In (R,S)-4b, the l values of these protons
are 8.62 and 7.58 ppm, and in (R,R)-4b are 7.89 and
8.22 ppm, respectively. That is, the proton C(4)H
appears in the diastereomer (R,S)-4b shifted to higher
fields than in diastereomer (R,R)-4b (Dl(H4)=0.73
ppm), and the opposite occurs in the case of the proton
C(6)H (Dl(H6)=−0.64 ppm). This is common in this
kind of complex, for which reason cyclopalladium com-
pounds have also been used for the determination of
the enantiomeric excess of Lewis bases.20–23
The protons of the two aromatic rings of the diben-
zophosphole appear at different l values in compound
4a in spite of the symmetry of the free phosphine. This
can only be explained by the relative orientation of the
plane determined by the naphthyl group and the phenyl
groups of the dibenzophosphole ligand (see the geome-
try of related compound (R,S)-4b in Fig. 1). As a
consequence of this arrangement, the shielding effects
of the two aromatic rings of the phosphole by the
p-system of the naphthyl group are very different, and
the two equivalent protons in the free phosphine appear
with different l values in cyclopalladium compound 4a.
For example, of the two C(4)H protons (see Scheme 1)
one is seen at 8.22 ppm, and the other is seen in the
complex signal between 7.62 and 7.12 ppm, showing a
difference in l values of >0.6 ppm. The C(1)H protons
give signals at 7.94 and 7.91 ppm, as two independent
doublets. The 13C NMR spectra can be easily assigned
using 13C–31P coupling constants, and therefore HSQC
Diastereomeric mixture 4b (428 mg) was eluted at room
temperature on a SiO2 column with hexane–AcOEt
(1:1) as eluent. The fractions eluted were checked by
TLC. The first diastereomer eluted (R,S)-4b was
obtained in 85% yield (182 mg), with a diastereomeric
excess of >95%, and the second diastereomer (R,R)-4b
was obtained with only 85% d.e.
In order to establish the absolute configuration of the
phosphine, the crystal structure of (R,S)-4b was deter-
mined by X-ray diffraction (see Fig. 2). The crystal
structure consists of discrete molecules separated by
van der Waals distances. The structure, bond distances
and angles are similar to those reported for related
metallacycles38,39 (see Table 1). The palladium atom is
in a square-planar environment, coordinated to carbon,
chlorine, nitrogen and phosphorus atoms. The phos-
phorus and nitrogen atoms adopt a trans arrangement.
The methyl group of the stereogenic carbon atom occu-
pies an axial position and the metallacycle adopts a d
conformation. The absolute configuration of the phos-
phorus atom in (R,S)-4b is (S).
1
bidimensional H–13C heterocorrelation allows the total
1
assignation of the H NMR spectra (see Section 3).
The reaction of dimer 3 with the dibenzophosphole 2b
afforded the mononuclear complex [PdCl(C-N)(P*)] 4b
(see Scheme 2) as a 1:1 mixture of diastereomers,
1
(R,S)-4b and (R,R)-4b. H NMR analysis also shows
Reaction of dimer 3 with the dibenzophosphole 2c
afforded the mononuclear complex [PdCl(C-N)(P*)] 4c
(see Scheme 2) as a 1:1 mixture of diastereomers,
Figure 1. Relative positions of the naphthyl group and the
dibenzophosphole ligand in the cyclopalladium derivative,
(R,S)-4b.
Figure 2. ORTEP plot of the structure of (R,S)-4b.

1990
E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
,
Table 1. Selected bond lengths (A) and angles (°) for
(R,S)-4b
ture, from a SiO2 column with CHCl3–acetone (100/3)
as eluent. The first diastereomer eluted (R,S,S)-4c was
obtained in 77% yield (400 mg), with a d.e. of >95%,
and the second diastereomer (R,R,S)-4c was obtained
in 44% yield with d.e. of 91%
Atoms
Distance
Atoms
Distance
Pd(1)ꢀC(1)
Pd(1)ꢀN(1)
Pd(1)ꢀP(1)
Pd(1)ꢀCl(1)
2.032(7)
2.114(16)
2.234(4)
2.393(2)
P(1)ꢀC(24)
P(1)ꢀC(13)
P(1)ꢀC(26)
1.729(19)
1.807(9)
1.899(15)
Unfortunately neither of the two diastereomers of 4c
afforded crystals suitable for the determination of their
structure by X-ray diffraction. Nevertheless we can
propose the absolute configuration of both diastereo-
Atoms
Angle
Atoms
Angle
1
mers on the basis of H NMR data.
C(1)ꢀPd(1)ꢀN(1)
C(1)ꢀPd(1)ꢀP(1)
N(1)ꢀPd(1)ꢀP(1)
C(1)ꢀPd(1)ꢀCl(1)
N(1)ꢀPd(1)ꢀCl(1)
P(1)ꢀPd(1)ꢀCl(1)
C(24)ꢀP(1)ꢀPd(1)
C(13)ꢀP(1)ꢀPd(1)
81.1(5)
97.2(4)
177.7(3)
170.9(4)
89.9(3)
C(26)ꢀP(1)ꢀPd(1)
C(24)ꢀP(1)ꢀC(13)
123.4(10)
91.4(6)
NOE techniques40–45 or NMR chemical shift regu-
larities46,47 can be used to determine the absolute
configuration of coordinated chiral diphosphines. Dun-
ina et al.48 have recently extended these studies to the
monodentate P-stereogenic ligand, tert-butylphenyl(4-
bromophenyl)phosphine. They show that the absolute
configuration of this phosphine can be assigned
through NMR techniques by using the homochiral
palladacycle as a reference point. The difference in l
values of the aromatic protons of the dibenzophosp-
hole, C(4)H and C(6)H, in compounds 4 is almost
independent of the substituents of the aromatic ring
and is great enough to preclude possible mistakes in the
assignment of the absolute configuration of the phos-
phine (see Figs. 3 and 4). This difference can be
explained by the relative disposition of the planes deter-
mined by the naphthyl group and by the phenyl groups
of the dibenzophosphole ligand (see Fig. 1). In all cases
the proton located near the naphthyl group appears at
lower fields than the proton located on the other side.
As a consequence, l values of C(4)H and C(6)H can be
used to assign the absolute configuration of the phos-
phine in the cyclopalladium derivatives.
C(11)ꢀN(1)ꢀPd(1) 105.0(10)
C(2)ꢀC(1)ꢀPd(1) 126.1(8)
C(12)ꢀC(11)ꢀC(10) 113.9(14)
91.75(11) C(12)ꢀC(11)ꢀN(1) 110.5(10)
122.6(4)
115.1(5)
C(10)ꢀC(11)ꢀN(1) 107.2(9)
Atoms
Angle
C(1)ꢀPd(1)ꢀP(1)ꢀC(13)
C(1)ꢀPd(1)ꢀP(1)ꢀC(24)
C(1)ꢀPd(1)ꢀP(1)ꢀC(26)
C(1)ꢀPd(1)ꢀN(1)ꢀC(11)
Pd(1)ꢀN(1)ꢀC(11)ꢀC(10)
Pd(1)ꢀN(1)ꢀC(11)ꢀC(12)
77.5(4)
−31.8(6)
−157.6(7)
34.6(6)
−40.0(11)
84.6(15)
1
(R,S,S)-4c and (R,R,S)-4c. H NMR data also showed
the cis disposition of the phosphorus relative to the
metallated carbon atom and significant differences in
the l values of both diastereomers: the l values of
C(4)H and C(6)H are 7.88 and 8.23 ppm in (R,S,S)-4c
and 7.07 and 9.02 ppm in (R,R,S)-4c (Dl(H4)=0.88
ppm and Dl(H6)=−0.79 ppm), which shows that such
criteria can be used for the determination of the absolute
configuration of the phosphorus atom in our complexes.
The action of dppe on the enantiomerically pure cyclo-
palladium diastereomers 4c led to the enantiopure free
dibenzophospholes 2c. The displacement proceeds with
Compound 4c (1061 mg) was eluted at room tempera-
Figure 3. C(6)H in compound (R,S)-4b, and C(4)H in (R,R)-4b appear at lower fields than that in the other diastereomer due to
its proximity to the naphthyl group, and can be used to assign the absolute configuration of the phosphine in the cyclopalladium
derivative (stereochemical descriptors refer only to the phosphorus atom).

E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
1991
Figure 4. C(6)H in compound (R,S,S)-4c, and C(4)H in (R,R,S)-4c appear at lower fields than that in the other diastereomer due
to its proximity to the naphthyl group, and can be used to assign the absolute configuration of the phosphine in the
cyclopalladium derivative (stereochemical descriptors refer only to the phosphorus atom).
retention of the configuration at phosphorus as verified
by the quantitative regeneration of the starting material
4c from the free ligand and the binuclear cyclopalla-
dium derivative 3.
configuration.49 The enantiomeric excess of (S,S)-1c
1
was determined by H NMR and adding 0.6 equiv. of
europium(III) tris{3-(heptafluoropropylhydroxymethyl-
ene)-(+)-camphorate} as resolving agent. The aromatic
signals for C(23)H and C(24)H showed different l
values for each diastereomer (see Fig. 5) and can be
used to confirm that hydrogen peroxide oxidizes with
The oxidation of free dibenzophospholes 2c afforded
the corresponding oxides 1c with complete retention of
Figure 5. C(23)H shows different l values for each diastereomer by addition of europium(III) tris{3-(heptafluoropropylhydroxy-
methylene)-(+)-camphorate} to a mixture of (R,S)-1c and (S,S)-1c in CDCl3 (stereochemical descriptors refer only to the
phosphorus atom).

1992
E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
complete retention of configuration. (R,S)-1c
diastereomer was not detected after the oxidation of
enantiomerically pure (R,S)-2c. Also HPLC with a
CSP-150 chiral stationary phase derived from N-[N-
(3,5-dinitrobenzoyl)-(S)-phenylalanyl]-(3-triethoxysilyl)
propylamide was used to determine the enantiomeric
excess of (R,S)-1c. Very good resolution was achieved
(RS=1.41) using 1 mL/min flow of heptane–iso-
propanol (9:1), and enantiomeric excess of 98% was
measured for (S)-1c.
Masas de la Facultad de Qu´ımica (University of
Co´rdoba).
3.2. Materials and synthesis
All the reactions involving free phosphines were carried
out using Schlenk techniques under an argon atmo-
sphere. All solvents were dried and degassed by stan-
dard methods. Tetrahydrofuran and toluene were
distilled from sodium benzophenone, under nitrogen,
before use. Dimethylformamide was distilled and stored
,
This work provides a general application procedure to
resolve racemic and diastereomeric mixtures of diben-
zophosphole 5-oxides using enantiomerically pure
cyclopalladates derived from (R)-1-(1-naphthyl)-
ethylamine, to assign the absolute configuration of
over 4 A molecular sieves. All chemicals were of com-
mercial grade and used as received. Compounds 1a and
1c were prepared according to procedures described
elsewhere.52
1
phosphorus atom using H NMR chemical shift regu-
3.3. Synthesis of 3-cyano-5-methyl-5H-dibenzophos-
phole 5-oxide 1b
larities, and to determine the enantiomeric excess of
dibenzophosphole 5-oxides using europium shift
1
reagents in H NMR and HPLC with a chiral station-
3-Bromo-5-methyl-5H-dibenzophosphole 5-oxide (750
mg, 2.56 mmol), prepared according to the procedure
described elsewhere,52 was dissolved in anhydrous N,N-
dimethylformamide (20 mL). Potassium cyanide (300
mg, 4.61 mmol), palladium(II) acetate (98 mg, 0.44
mmol), triphenylphosphine (235 mg, 0.90 mmol) and
calcium hydroxide (32 mg, 0.44 mmol) were added and
the resulting mixture was heated to 100°C for 1 h under
an inert atmosphere. Solvent was removed by vacuum
distillation at rt (2 mmHg) and 3-cyano-5-methyl-5H-
dibenzophosphole 5-oxide (540 mg, 88%) was isolated
as a white solid by column chromatography, eluting
with CH2Cl2–CH3OH 24:1; mp 185°C decomp. (from
CH2Cl2); TLC (SiO2, CH2Cl2–CH3OH 96:4): Rf=0.31;
IR (film): w=3056 (arCꢀH s), 2908 (CꢀH s), 2229 (CꢁN
ary phase.
3. Experimental
3.1. General
Melting points were determined in a Ko¨fler apparatus
provided with a Reichert Thermovar microscope and
are uncorrected. TLC was carried out on SiO2 (Alu-
gram SIL G/UV254 Macherey–Nagel 0.25 mm) and
spots were located with UV light. Flash chromatogra-
phy was carried out on SiO2 (Silica Gel 60 A CC,
Merck). Organic extracts were dried over anhydrous
MgSO4, and solutions were evaporated under reduced
pressure using a rotary evaporator. IR spectra were
recorded on a Nicolet 510 FT-IR spectrometer. NMR
spectra were measured with Varian Gemini-200 (200
MHz), Varian Unity-300 (300 MHz) and Varian VXR-
500 (500 MHz) spectrometers; data are given in l/ppm,
1
s), 1188 (PꢂO s) cm−1; H NMR (300 MHz, CDCl3,
25°C, TMS): l=8.04 (ddd, 3J(H,P)=9.3 Hz,
5
4J(H2,H4)=1.7 Hz, J(H1,H4)=0.8 Hz, 1 H, H4), 7.87–
7.76 (complex signal, 4 H, H1+H2+H6+H9), 7.59 (dddd,
3J(H8,H9)=7.5 Hz, 3J(H7,H8)=7.5 Hz, 5J(H,P)=1.5
Hz, 4J(H6,H8)=1.2 Hz,
1
H, H8), 7.48 (dddd,
1
referenced to TMS for H NMR, to CDCl3 (77.0 ppm)
3J(H6,H7)=7.5 Hz, 3J(H7,H8)=7.5 Hz, 4J(H,P)=3.6
4 2
for 13C NMR and to P(OMe)3 (140.18 ppm) for 31P
NMR, and J values are given in Hz. HPLC experi-
ments were carried out on an Hewlett–Packard HP
1090 liquid chromatograph equipped with a Philips
PU4020 UV detector. The chiral stationary phase was
packed into a stainless-steel tube (100×4.6 mm I.D.) by
the slurry method according to Coq et al.51 The volume
of sample injected was 5 mL (1 mg/mL), the flow-rate of
the pump was 1 mL/min and the detection wavelength
was 254 nm. Optical rotations (c g/100 mL) were
determined at 20°C using a Perkin–Elmer 241-MC
polarimeter at 589 nm. Mass spectra were measured in
chemical-impact (CI, NH3) mode with an Hewlett–
Packard 5988A spectrometer, or with a Fisons VG-
Quattro spectrometer. Then the samples were
introduced into a matrix of 2-nitrobenzyl alcohol for
FAB analysis and subjected to bombardment with cae-
sium atoms. High-resolution mass spectra were per-
formed on an Autospec/VG in chemical-impact (CI,
NH3) mode by the Departament de Qu´ımica Orga`nica
Biolo`gica (CSIC), Barcelona and in chemical-impact
(CI, CH4) mode by the Servicio de Espectrometr´ıa de
Hz, J(H7,H9)=0.9 Hz, 1 H, H7), 1.84 (d, J(H,P)=
13.8 Hz, 3 H, H14) ppm; 13C NMR (75 MHz, CDCl3,
2
25°C): l=144.47 (d, J(C,P)=21.2 Hz, C10), 138.62 (d,
2J(C,P)=20.3 Hz, C11), 136.86 (d, 4J(C,P)=1.8 Hz,
1
C2H), 134.01 (d, J(C,P)=101.3 Hz, C12), 133.69 (d,
4J(C,P)=2.1 Hz, C8H), 133.19 (d, J(C,P)=104.0 Hz,
1
C13), 132.49 (d, 2J(C,P)=10.6 Hz, C4H), 130.84 (d,
2J(C,P)=10.9 Hz, C6H), 129.20 (d, J(C,P)=10.0 Hz,
3
C7H), 122.35 (d, 3J(C,P)=9.7 Hz, C9H), 121.92 (d,
3J(C,P)=9.4 Hz, C1H), 117.83 (d, 4J(C,P)=1.8 Hz,
CꢁN), 112.66 (d, 3J(C,P)=12.5 Hz, C3), 16.11 (d,
1J(C,P)=71.9 Hz, C14H3) ppm; 31P NMR (121 MHz,
CDCl3, 25°C, P(OMe)3): l=35.99 (s) ppm; MS (70 eV,
CI, NH3): m/z (%): 240 (15) [M+1]+, 257 (100) [M+18]+,
274 (15) [M+35]+; HRMS (70 eV, EI): m/z: 239.0505
[M]+, C14H10NOP requires 239.0500.
3.4. Synthesis of 5-methyl-5H-dibenzophosphole 2a
Distilled triethylamine (0.74 mL, 537 mg, 7.33 mmol)
was added to a solution of 5-methyl-5H-dibenzophos-
phole 5-oxide 1a (783 mg, 3.66 mmol) in anhydrous

E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
1993
toluene (20 mL) under an inert atmosphere at rt.
Trichlorosilane (1.1 mL, 1.48 g, 7.90 mmol) was added
and the mixture was heated under reflux for 2 h. 30%
aqueous NaOH solution (20 mL) was deoxygenated
and then added to the reaction mixture previously
cooled to 0°C. After vigorous stirring for 0.5 h the
organic layer was extracted under nitrogen, dried and
the solvent removed. 5-Methyl-5H-dibenzophosphole
(672 mg, 93%) was isolated as a colourless oil which
was checked only by NMR spectroscopy due to its
rapid oxidation in contact with air. Previously
described53,54 13C NMR spectroscopy assignation for
this compound is not consistent with our COSY and
HSQC spectra; 1H NMR (500 MHz, CDCl3, 25°C,
for 0.5 h the organic layer was extracted under nitro-
gen, dried and the solvent removed. (SC)-5-Ethyl-3-(2-
methylbutoxy)-7-(4-undec-10-enoxyphenoxycarbonyl)-
5H-dibenzophosphole was isolated as a colourless oil
which was rapidly converted into cyclopalladate 3c due
to its rapid oxidation in contact with air.
3.7. Synthesis of bis[(R)-1-(1-aminoethyl)-
naphthyl-C2,N]di-m-chlorodipalladium(II) 3
Palladium(II) acetate (1.9 g, 8.62 mmol) was dissolved
in acetic acid (100 mL). R-(+)-1-(1-Naphthyl)-
ethylamine (1.5 g, 8.91 mmol) was added and the
solution was stirred under an argon atmosphere at 60°C
for 5 h. The solvent was removed and the resulting
residue was dissolved in dichloromethane and filtered
with Celite. The green solid obtained after
dichloromethane evaporation was dissolved in acetone
(120 mL) and lithium chloride (752 mg, 17.7 mmol) was
added. The solution was stirred at rt for 30 min. Water
(300 mL) was added, the pale brown solution was
stirred for 0.5 h and a green precipitate was obtained.
After filtering and drying in a low-pressure oven,
bis[(R)-1-(1-aminoethyl)naphthyl-C2,N]di-m-chlorodi-
palladium(II) (2.7 g, 100%) was isolated as a pale green
solid, which was found to be identical by 1H NMR
spectroscopy to the previously described compound.31
3
4
TMS): l=7.93 (ddd, J(H1,H2)=7.8 Hz, J(H1,H3)=
1.2 Hz, 5J(H1,H4)=0.9 Hz, 2 H, H1), 7.73 (dddd,
3J(H3,H4)=7.5 Hz, 3J(H,P)=5.0 Hz, 4J(H2,H4)=1.2
Hz, 5J(H1,H4)=0.9 Hz,
2
H, H4), 7.46 (ddd,
3
4
3J(H1,H2)=7.8 Hz, J(H2,H3)=7.5 Hz, J(H2,H4)=1.2
Hz,
2
H, H2), 7.35 (dddd, 3J(H3,H4)=7.5 Hz,
3J(H2,H3)=7.5 Hz, 4J(H,P)=2.7 Hz, 4J(H1,H3)=1.2
2
Hz, 2 H, H3), 1.43 (d, J(H,P)=1.8 Hz, 3 H, H14) ppm;
13C NMR (75 MHz, CDCl3, 25°C): l=145.08 (d,
2J(C,P)=4.0 Hz, C10), 143.30 (d, 2J(C,P)=1.8 Hz, C12),
129.58 (d, 2J(C,P)=21.5 Hz, C4H), 128.36 (s, C2H),
127.24 (d, 3J(C,P)=7.7 Hz, C3H), 121.47 (s, C1H),
14.06 (d, 1J(C,P)=20.3 Hz, C14H3) ppm; 31P NMR
(121 MHz, CDCl3, P(OMe)3): l=−27.52 (s) ppm.
3.8. Synthesis of (R)-[1-(1-aminoethyl)-naphthyl-
C2,N][chloro][5-methyl-5H-dibenzophosphole-
P]palladium(II) 4a
3.5. Synthesis of 3-cyano-5-methyl-5H-dibenzophos-
phole 2b
3-Cyano-5-methyl-5H-dibenzophosphole 5-oxide 1b
(178 mg, 0.80 mmol), a mixture of 50% (RP) and 50%
(SP) product, was dissolved in anhydrous toluene (10
mL) under an inert atmosphere at rt. Distilled triethy-
lamine (0.30 mL, 218 mg, 2.16 mmol) and then
trichlorosilane (0.20 mL, 269 mg, 1.99 mmol) were
added and the resulting solution was heated under
reflux for 2 h. 30% NaOH aqueous solution (10 mL)
was deoxygenated and then added to the reaction mix-
ture previously cooled to 0°C. After vigorous stirring
for 0.5 h the organic layer was extracted under nitro-
gen, dried and the solvent removed. Reduced 3-cyano-
5-methyl-5H-dibenzophosphole was isolated as an
orange oil which was rapidly converted into cyclopalla-
date 3b due to its rapid oxidation in contact with air.
5-Methyl-5H-dibenzophosphole 2a (159 mg, 0.80
mmol) was dissolved in anhydrous tetrahydrofuran (10
mL).
Bis[(R)-1-(1-aminoethyl)naphthyl-C2,N]di-m-
chlorodipalladium(II) 3 (250 mg, 0.40 mmol) was added
and the resulting solution was stirred under nitrogen at
rt for 15 min. The solvent was removed and (R)-[1-(1-
aminoethyl)naphthyl-C2,N][chloro][5-methyl-5H-diben-
zophosphole-P]palladium(II) (339 mg, 83%) was
isolated as a yellow solid after column chromatography
eluting with CHCl3–CH3OH 100:3; mp 220°C decomp.
(from CH2Cl2); TLC (SiO2, CHCl3–CH3OH 100:3):
Rf=0.63; IR (film): w=3210 (NH2 s), 3040 (arCꢀH s),
2950 (CꢀH s), 1570 (NH2 l) cm−1; 1H NMR (300 MHz,
CDCl3, 25°C, TMS): l=8.22 (dd, 3J(H,P)=8.4 Hz,
3J(H3,H4)=8.4 Hz,
3J(H1,H2)=8.7 Hz,
1
1
H, [H4a, H4b]), 7.94 (d,
H, [H1a, H1b]), 7.91 (d,
3.6. Synthesis of (SC)-5-ethyl-3-(2-methylbutoxy)-7-(4-
3J(H1,H2)=8.7 Hz, 1 H, [H1a, H1b]), 7.62–7.17 (com-
plex signal, 9 H, H2+H3+[H4a, H4b]+H5%+H6%+H7%+H8%),
6.71 (d, 3J(H3%,H4%)=8.5 Hz, 1 H, H4%), 5.93 (dd,
undec-10-enoxyphenoxycarbonyl)-5H-dibenzophosphole
2c
3J(H3%,H4%)=8.5 Hz, J(H,P)=7.2 Hz, 1 H, H3%), 5.06
4
(SC)-5-Ethyl-3-(2-methylbutoxy)-7-(4-undec-10-
(q, 3J(H11%,H12%)=6.3 Hz, 1 H, H11%), 4.31 (complex
signal, 1 H, H13%a), 3.54 (complex signal, 1 H, H13%b),
1.93 (d, 2J(H,P)=10.8 Hz, 3 H, H14), 1.90 (d,
3J(H11%,H12%)=6.3 Hz, 3 H, H12%) ppm; 13C NMR (75
MHz, CDCl3, 25°C): l=[151.32 (s), 147.33 (s)] [C1%, C2%,
C9%, C10%], [143.13 (d, 2J(C,P)=8.2 Hz), 142.58 (d,
enoxyphenoxycarbonyl)-5H-dibenzophosphole 5-oxide
1c (699 mg, 1.16 mmol), a mixture of 50% (RP) and
50% (SP) product, was dissolved in anhydrous toluene
(20 mL) under an inert atmosphere at rt. Distilled
triethylamine (0.23 mL, 167 mg, 1.65 mmol) and then
trichlorosilane (0.35 mL, 470 mg, 3.47 mmol) were
added and the resulting solution was heated under
reflux for 2 h. 30% NaOH aqueous solution (20 mL)
was deoxygenated and then added to the reaction mix-
ture previously cooled to 0°C. After vigorous stirring
2J(C,P)=8.6 Hz)] [C10a, C10b], [136.38 (d, J(C,P)=52.5
1
1
Hz), 135.87 (d, J(C,P)=48.9 Hz)] [C12a, C12b], 134.64
3
2
(d, J(C,P)=12.8 Hz, C3%H), 131.74 (d, J(C,P)=14.3
Hz) [C4aH, C4bH], [131.28 (s), 131.05 (s)] [C2aH, C2bH],
2
130.86 (d, J(C,P)=14.0 Hz) [C4aH, C4bH], [128.81 (d,

1994
E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
3J(C,P)=10.6 Hz), 128.51 (d, 3J(C,P)=11.0 Hz)]
[C3aH, C3bH], 128.23 (s, C5%H), 125.53 (s, C7%H), 124.94
(d, JCꢀP 5.5, C4%H), 123.98 (s, C6%H), 123.32 (s, C8%H),
[121.50 (d, J(C,P)=5.8 Hz), 121.32 (d, J(C,P)=5.8
Hz)] [C1aH, C1bH], 57.06 (s, C11%H), 25.65 (s, C12%H3),
16.08 (d, 1J(C,P)=29.8 Hz, C14H3) ppm; 31P NMR
(121 MHz, CDCl3, P(OMe)3): l=16.92 (s) ppm; MS
(10 kV, positive FAB, Cs, NBA): m/z: 474 [M−Cl]+.
7.5 Hz, 3J(H8,H9)=7.5 Hz, 4J(H6,H8)=1.0 Hz,
5J(H,P)=1.0 Hz, 1 H, H8), 7.47 (complex signal, 3 H,
H7+H5%+H7%),
7.27
(ddd,
3J(H6%,H7%)=7.0
Hz,
3J(H5%,H6%)=7.0 Hz, 4J(H6%,H8%)=1.0 Hz, 1 H, H6%), 7.23
3 4
3
3
(dd, J(H7%,H8%)=8.0 Hz, J(H6%,H8%)=1.0 Hz, 1 H, H8%),
6.74 (d, 3J(H3%,H4%)=8.5 Hz, 1 H, H4%), 5.87 (dd,
3J(H3%,H4%)=8.5 Hz, J(H,P)=7.0 Hz, 1 H, H3%), 5.06
4
(q, 3J(H11%,H12%)=6.5 Hz, 1 H, H11%), 4.44 (complex
signal, 1 H, H13%a), 3.57 (complex signal, 1 H, H13%b),
1.92 (d, 2J(H,P)=11.0 Hz, 3 H, H14), 1.90 (d,
3J(H11%,H12%)=6.5 Hz, 3 H, H12%); 13C NMR (75 MHz,
CDCl3, 25°C): l=151.68 (s) [C1%, C2%, C9%, C10%], 146.84
3.9. Synthesis of 4b and separation of (R,S)-4b and
(R,R)-4b
Bis[(R)-1-(1-aminoethyl)naphthyl-C2,N]di-m-chlorodi-
palladium(II) 3 (250 mg, 0.40 mmol) was added to a
solution of 2b previously obtained in anhydrous tetra-
hydrofuran (50 mL) and the resulting solution was
stirred under nitrogen at rt for 15 min. The solvent was
removed and the yellow solid obtained was purified by
column chromatography eluting with hexane–AcOEt
1:1. Firstly, (RC,SP)-[1-(1-aminoethyl)naphthyl-C2,N]-
[chloro][3 - cyano - 5 - methyl - 5H - dibenzophosphole-P]-
palladium(II) (R,S)-4b (182 mg, 85%) was isolated as
(d, J(C,P)=7.9 Hz) [C10, C11], 146.67 (s) [C1%, C2%, C9%,
2
2
C10%], 140.75 (d, J(C,P)=7.6 Hz) [C10, C11], 138.24 (d,
1J(C,P)=49.7 Hz) [C12, C13], 136.77 (d, J(C,P)=47.3
1
Hz) [C12, C13], 134.71 (s, C2H), 134.39 (d, 2J(C,P)=15.5
Hz, C4H), 134.02 (d, J(C,P)=12.5 Hz, C3%H), 131.94
3
(d, J(C,P)=14.3 Hz, C6H), 131.70 (s, C8H), 130.99 (s)
2
[C1%, C2%, C9%, C10%], 130.37 (d, J(C,P)=10.7 Hz, C5%H),
6
128.30 (s, C7%H), 125.85 (s, C6%H), 125.14 (d, J(C,P)=
4
5.5 Hz, C4%H), 124.29 (s, C8%H), 123.39 (s, C7H), 122.64
3
3
(d, J(C,P)=5.4 Hz) [C1H, C9H], 121.86 (d, J(C,P)=
5.5 Hz) [C1H, C9H], 118.08 (s, CꢁN), 111.81 (d,
3J(C,P)=12.2 Hz, C3), 57.39 (s, C11%H), 25.66 (s,
C12%H3), 15.77 (d, 1J(C,P)=29.5 Hz, C14H) ppm; 31P
NMR (121 MHz, CDCl3, P(OMe)3): l=18.77 (s) ppm.
a
yellow solid. Finally (RC,RP)-[1-(1-aminoethyl)-
naphthyl-C2,N][chloro][3-cyano-5-methyl-5H-dibenzo-
phosphole-P]palladium(II) (R,R)-4b was obtained with
a small amount of the (R,S)-4b product.
3.9.1. (R,S)-4b. TLC (SiO2, hexane–AcOEt 6:4): Rf=
0.40; [h]2D0=+99.8 (c 1.02, CHCl3); 1H NMR (500 MHz,
3.10. Synthesis of 4c and separation of (R,S,S)-4c and
(R,R,S)-4c
3
CDCl3, 25°C, TMS): l=8.62 (d, J(H,P)=8.5 Hz, 1 H,
H4), 7.98 (complex signal, 2 H, H1+H9), 7.81 (d,
3J(H1,H2)=8.5 Hz, 1 H, H2), 7.58 (complex signal, 2 H,
Bis[(R)-1-(1-aminoethyl)naphthyl-C2,N]di-m-chlorodi-
palladium(II) 3 (362 mg, 0.58 mmol) was added to a
solution of the 2c compound previously obtained into
anhydrous tetrahydrofuran (50 mL). The resulting solu-
tion was stirred under nitrogen at rt for 15 min. The
solvent was removed and the oil obtained was purified
by SiO2 column chromatography (200 g), eluting with
CHCl3–acetone 49:1. Firstly, (RC11%,SP,SC17)-[1-(1-
aminoethyl)naphthyl-C2,N][chloro][5-ethyl-3-(2-methyl-
butoxy)-7-(4-undec-10-enoxyphenoxycarbonyl)-5H-di-
benzophosphole-P]palladium(II) (R,S,S)-4c (400 mg,
77%), and then (RC11%,RP,SC17) - [1 - (1 - aminoethyl)-
naphthyl-C2,N][chloro][5-ethyl-3-(2-methylbutoxy)-7-
(4-undec-10-enoxyphenoxycarbonyl)-5H-dibenzophos-
phole-P]palladium(II) (R,R,S)-4c (227 mg, 44%) were
isolated as yellow solids.
3
H6+H8), 7.54 (d, J(H7%,H8%)=8.5 Hz, 1 H, H8%), 7.49
(complex signal, 1 H, H7%), 7.28 (complex signal, 3 H,
3
H5%+H6%+H7), 6.76 (d, J(H3%,H4%)=8.5 Hz, 1 H, H4%),
3
4
5.87 (dd, J(H3%,H4%)=8.5 Hz, J(H,P)=7.0 Hz, 1 H,
H3%), 5.10 (q, 3J(H11%,H12%)=6.5 Hz, 1 H, H11%), 4.33
(complex signal, 1 H, H13%a), 3.58 (complex signal, 1 H,
H13%b), 1.96 (d, J(H,P)=11.0 Hz, 3 H, H14), 1.93 (d,
2
3J(H11%,H12%)=6.5 Hz, 3 H, H12%) ppm; 13C NMR (75
MHz, CDCl3, 25°C): l=151.49 (s) [C1%, C2%, C9%, C10%],
147.22 (s) [C1%, C2%, C9%, C10%], 146.14 (d, J(C,P)=8.2
2
Hz) [C10, C11], 141.33 (d, J(C,P)=7.3 Hz) [C10, C11],
2
137.49 (d, 1J(C,P)=46.4 Hz) [C12, C13], 136.97 (d,
1J(C,P)=50.4 Hz) [C12, C13], 135.35 (d, J(C,P)=15.2
2
Hz, C4H), 134.93 (s, C2H), 134.73 (d, 3J(C,P)=12.4 Hz,
C3%H), 131.53 (s, C8H), 131.32 (d, 2J(C,P)=14.3 Hz,
C6H), 130.95 (s) [C1%, C2%, C9%, C10%], 129.97 (d, J(C,P)=
6
10.9 Hz, C5%H), 128.28 (s, C7%H), 125.80 (s, C7H), 125.09
3.10.1. (R,S,S)-4c. TLC (SiO2, CHCl3–acetone 49:1):
Rf=0.24; [h]2D0=−139.0 (c 1.29, CH2Cl2); 1H NMR (500
(d, J(C,P)=5.5 Hz, C4%H), 124.23 (s, C6%H), 123.41 (s,
4
C8%H), 122.51 (d, J(C,P)=5.5 Hz) [C1H, C9H], 122.00
MHz, CDCl3, 25°C, TMS): l=8.29 (ddd, J(H8,H9)=
3
3
(d, 3J(C,P)=5.5 Hz) [C1H, C9H], 118.25 (s, CꢁN),
8.5 Hz, J(H6,H8)=1.5 Hz, J(H,P)=1.5 Hz, 1 H, H8),
8.23 (dd, 3J(H,P)=8.5 Hz, 4J(H6,H8)=1.5 Hz, 1 H,
H6), 7.88 (complex signal, 3 H, H1+H4+H9), 7.53 (d,
4
5
112.08 (d, 3J(C,P)=11.9 Hz, C3), 57.45 (s, C11%H), 25.64
(s, C12%H3), 15.96 (d, 1J(C,P)=29.7 Hz, C14H3) ppm; 31
P
3
NMR (121 MHz, CDCl3, P(OMe)3): l=18.99 (s) ppm.
3J(H7%,H8%)=8.0 Hz, 1 H, H8%), 7.47 (d, J(H5%,H6%)=8.0
Hz,
1
H, H5%), 7.28 (ddd, 3J(H7%,H8%)=8.0 Hz,
3.9.2. (R,R)-4b. TLC (SiO2, hexane–AcOEt 6:4): Rf=
3J(H6%,H7%)=7.0 Hz, 4J(H5%,H7%)=1.0 Hz, 1 H, H7%), 7.22
(ddd, 3J(H5%,H6%)=8.0 Hz, 3J(H6%,H7%)=7.0 Hz,
1
0.33; H NMR (500 MHz, CDCl3, 25°C, TMS): l=
8.22 (dd, 3J(H6,H7)=8.0 Hz, 3J(H,P)=8.0 Hz, 1 H,
H6), 7.98 (complex signal, 2 H, H1+H9), 7.89 (dd,
3J(H,P)=8.5 Hz, 4J(H2,H4)=1.0 Hz, 1 H, H4), 7.77
4J(H6%,H8%)=1.0 Hz, 1 H, H6%), 7.17 (ddd, J(H1,H2)=
3
4
5
9.0 Hz, J(H2,H4)=1.5 Hz, J(H,P)=1.5 Hz, 1 H, H2),
6.91 (d, 3J(H23,H24)=9.0 Hz, 2 H, H23), 6.81 (d,
3
(ddd,
3J(H1,H2)=8.0
Hz,
5J(H,P)=1.0
Hz,
3J(H23,H24)=9.0 Hz, 2 H, H24), 6.75 (d, J(H3%,H4%)=
3
4J(H2,H4)=1.0 Hz, 1 H, H2), 7.64 (dddd, J(H7,H8)=
8.5 Hz, 1 H, H4%), 6.00 (dd, 3J(H3%,H4%)=8.5 Hz,

E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
1995
4J(H,P)=6.5 Hz, 1 H, H3%), 5.80 (complex signal, 1 H,
H35), 5.12 (q, 3J(H11%,H12%)=6.5 Hz, 1 H, H11%), 4.95
(complex signal, 2 H, H36), 4.13 (complex signal, 1 H,
H13%a), 3.93 (complex signal, 2 H, H16), 3.89 (t,
3J(H26,H27)=6.5 Hz, 2 H, H26), 3.55 (complex signal, 1
1.47–1.00 (complex signal, 14 H, H18+H28–33), 0.84 (d,
3J(H17,H20)=6.5 Hz, 3 H, H20), 0.79 (complex signal, 3
3
H, H15), 0.75 (t, J(H18,H19)=7.5 Hz, 3 H, H19) ppm;
13C NMR (75 MHz, CDCl3, 25°C): l=164.90 (s, CꢂO),
160.44 (d, 3J(C,P)=13.4 Hz, C3), 156.85 (s, C25), 151.18
2
3
2
H, H13%b), 2.70 (dq, J(H,P)=15.0 Hz, J(H14a,H15)=
(s) [C1%, C2%, C9%, C10%], 148.45 (d, J(C,P)=7.3 Hz, C11),
7.5 Hz, 1 H, H14a), 2.46 (complex signal, 1 H, H14b),
147.45 (s) [C1%, C2%, C9%, C10%], 144.22 (s, C22), 139.16 (s,
C35H), 137.37 (d, 1J(C,P)=48.9 Hz, C13), 135.45 (d,
2J(C,P)=6.7 Hz, C10), 134.64 (d, 3J(C,P)=12.2 Hz,
C3%H), 133.54 (s, C8H), 133.50 (d, 1J(C,P)=47.0 Hz,
3
2.03 (complex signal, 2 H, H34), 1.96 (d, J(H11%,H12%)=
6.5 Hz, 3 H, H12%), 1.90 (complex signal, 1 H, H17), 1.74
(complex signal, 2 H, H27), 1.60 (complex signal, 1 H,
H18a), 1.45–1.24 (complex signal, 13 H, H18b+H28–33),
1.03 (d, 3J(H17,H20)=6.5 Hz, 3 H, H20), 0.96 (t,
2
C12), 133.32 (d, J(C,P)=15.2 Hz, C6H), 130.96 (s) [C1%,
C2%, C9%, C10%], 128.63 (d, 6J(C,P)=10.7 Hz, C5%H),
128.27 (d, 3J(C,P)=2.4 Hz, C7), 125.60 (s, C7%H),
125.12 (d, 4J(C,P)=5.2 Hz, C4%H), 124.03 (s, C6%H),
123.26 (s, C1H+C8%H), 122.35 (s, C23H), 120.37 (d,
3J(C,P)=5.5 Hz, C9H), 118.67 (s, C2H), 116.45 (d,
2J(C,P)=15.2 Hz, C4H), 115.03 (s, C24H), 114.07 (s,
C36H2), 73.20 (s, C16H2), 68.37 (s, C26H2), 57.31 (s,
C11%H), 34.25 (s, C17H), 33.75 (s, C34H2), [29.46, 29.37,
29.32, 29.24, 29.06, 28.88] (s, C27H2+C29–33H2), [25.99,
25.85, 25.69] (s, C12%H3+C18H2+C28H2), 23.03 (d,
1J(C,P)=27.3 Hz, C14H2), 16.31 (s, C20H3), 11.05 (s,
C19H3), 8.23 (d, 2J(C,P)=4.9 Hz, C15H3) ppm; 31P
NMR (121 MHz, CDCl3, P(OMe)3): l=29.30 (s) ppm.
3
3J(H18,H19)=7.5 Hz, 3 H, H19), 0.84 (dt, J(H,P)=18.5
3
Hz, J(H14,H15)=7.5 Hz, 3 H, H15) ppm; 13C NMR (75
MHz, CDCl3, 25°C): l=164.66 (s, CꢂO), 161.19 (d,
3J(C,P)=12.8 Hz, C3), 156.85 (s, C25), 151.16 (s) [C1%,
2
C2%, C9%, C10%], 149.19 (d, C11, J(C,P)=7.4 Hz), 147.44
(s) [C1%, C2%, C9%, C10%], 144.03 (s, C22), 139.19 (s, C35H),
1
2
137.06 (d, J(C,P)=46.1 Hz, C13), 134.81 (d, J(C,P)=
7.0 Hz, C10), 134.60 (d, 3J(C,P)=12.2 Hz, C3%H), 133.91
(d, J(C,P)=50.1 Hz, C12), 133.24 (s, C8H), 132.98 (d,
1
2J(C,P)=14.9 Hz, C6H), 131.05 (s) [C1%, C2%, C9%, C10%],
128.38 (s, C7), 128.01 (d, 6J(C,P)=10.7 Hz, C5%H),
125.70 (s, C7%H), 125.21 (d, 4J(C,P)=5.2 Hz, C4%H),
124.13 (s, C6%H), 123.31 (s, C1H+C8%H), 122.25 (s,
C23H), 120.26 (d, 3J(C,P)=5.1 Hz, C9H), 119.10 (s,
C2H), 116.50 (d, 2J(C,P)=15.8 Hz, C4H), 114.99 (s,
C24H), 114.12 (s, C36H2), 73.35 (s, C16H2), 68.35 (s,
C26H2), 57.38 (s, C11%H), 34.75 (s, C17H), 33.73 (s,
C34H2), [29.43, 29.34, 29.29, 29.19, 29.04, 28.86] (s,
C27H2+C29–33H2), [26.06, 25.95, 25.69] (s, C12%H3+
C18H2+C28H2), 23.08 (d, 1J(C,P)=27.3 Hz, C14H2),
3.11. Discoordination of (R,S,S)-4c and oxidation of
(R,S)-2c to obtain (SC,SP)-5-ethyl-3-(2-methylbutoxy)-
7-(4-undec-10-enoxyphenoxycarbonyl)-5H-dibenzophos-
phole 5-oxide (S,S)-1c
(RC11%,SP,SC17) - [1 - (1 - Aminoethyl)naphthyl - C2,N]-
[chloro][5-ethyl-3-(2-methylbutoxy)-7-(4-undec-10-enoxy-
phenoxycarbonyl)-5H-dibenzophosphole-P]palladium-
(II) (R,S,S)-4c (227 mg, 0.25 mmol) was dissolved in
anhydrous tetrahydrofuran (50 mL), and 1,2-bis-
(diphenylphosphino)ethane (110 mg, 0.28 mmol) was
added to the solution. The resulting mixture was stirred
at rt under an inert atmosphere for 3 h. The solution
was evaporated, the residue dissolved in benzene and
filtered through Celite. 30% H2O2 (1 mL) was added
and the solution was stirred for a further 2 h.
Dichloromethane (100 mL) and water (100 mL) were
added. The organic layer was washed, dried and the
solvent removed. The residue was purified by column
chromatography eluting with hexane–AcOEt 4:6, yield-
ing (SC,SP)-5-ethyl-3-(2-methylbutoxy)-7-(4-undec-10-
enoxyphenoxycarbonyl)-5H-dibenzophosphole 5-oxide
(142 mg, 93%) as a yellow solid; mp 44.7°C (from
benzene); TLC (SiO2, AcOEt): Rf=0.58; [h]2D0=+20.2 (c
1.03, CH2Cl2); IR (film): w=2927 (CꢀH s), 1733 (CꢂO
2
16.50 (s, C20H3), 11.32 (s, C19H3), 8.44 (d, J(C,P)=4.8
Hz, C15H3) ppm; 31P NMR (121 MHz, CDCl3,
P(OMe)3): l=29.30 (s) ppm.
3.10.2. (R,R,S)-4c. TLC (SiO2, CHCl3–acetone 49:1):
1
Rf=0.16; [h]2D0=−9.05 (c 1.05, CH2Cl2); H NMR (500
3
MHz, CDCl3, 25°C, TMS): l=9.02 (dd, J(H,P)=8.5
Hz, 4J(H6,H8)=1.5 Hz,
1
H, H6), 8.37 (ddd,
3J(H8,H9)=8.5 Hz, 4J(H6,H8)=1.5 Hz, 5J(H,P)=1.5
3
4
Hz, 1 H, H8), 7.90 (dd, J(H8,H9)=8.5 Hz, J(H,P)=
1.0 Hz, 1 H, H9), 7.87 (dd, 3J(H1,H2)=8.5 Hz,
4J(H,P)=2.0 Hz, 1 H, H1), 7.51 (d, 3J(H7%,H8%)=8.0 Hz,
3
1 H, H8%), 7.44 (d, J(H5%,H6%)=8.0 Hz, 1 H, H5%), 7.25
(ddd, 3J(H7%,H8%)=8.0 Hz, 3J(H6%,H7%)=7.5 Hz,
4J(H5%,H7%)=1.0 Hz, 1 H, H7%), 7.19 (ddd, J(H5%,H6%)=
3
3
4
8.0 Hz, J(H6%,H7%)=7.5 Hz, J(H6%,H8%)=1.0 Hz, 1 H,
H6%), 7.14 (d, 3J(H23,H24)=9.5 Hz, 2 H, H23), 7.07 (ddd,
3J(H1,H2)=8.5 Hz, 4J(H2,H4)=1.5 Hz, 5J(H,P)=1.5
3
4
1
Hz, 1 H, H2), 7.04 (dd, J(H,P)=9.5 Hz, J(H2,H4)=
s), 1262 (CꢀOꢀC as. s), 1192 (PꢂO s) cm−1; H NMR
1.5 Hz, 1 H, H4), 6.90 (d, J(H23,H24)=9.5 Hz, 2 H,
(500 MHz, CDCl3, 25°C, TMS): l=8.55 (dd,
3
3
4
H24), 6.75 (d, J(H3%,H4%)=8.5 Hz, 1 H, H4%), 6.00 (dd,
3J(H,P)=10.0 Hz, J(H6,H8)=1.5 Hz, 1 H, H6), 8.28
4
3J(H3%,H4%)=8.5 Hz, J(H,P)=6.5 Hz, 1 H, H3%), 5.80
(dd, 3J(H8,H9)=8.0 Hz, 5J(H,P)=1.0 Hz, 1 H, H8),
(complex signal, 1 H, H35), 5.09 (q, J(H11%,H12%)=6.5
7.70 (complex signal, 2 H, H1+H9), 7.33 (dd, J(H,P)=
3
3
Hz, 1 H, H11%), 4.95 (complex signal, 2 H, H36), 4.17
10.0 Hz, J(H2,H4)=2.5 Hz, 1 H, H4), 7.07 (complex
4
(complex signal, 1 H, H13%a), 3.93 (t, J(H26,H27)=6.5
signal, 3 H, H2+H23), 6.87 (d, J(H23,H24)=7.0 Hz, 2
3
3
3
Hz, 2 H, H26), 3.61 (d, J(H16,H17)=6.0 Hz, 2 H, H16),
H, H24), 5.76 (complex signal, 1 H, H35), 4.91 (complex
3.56 (complex signal, 1 H, H13%b), 2.66 (dq, J(H,P)=
signal, 2 H, H36), 3.90 (t, J(H26,H27)=7.0 Hz, 2 H,
2
3
3
15.0 Hz, J(H14a,H15)=7.5 Hz, 1 H, H14a), 2.47 (com-
H26), 3.81 (complex signal, 2 H, H16), 2.12 (dq,
plex signal, 1 H, H14b), 2.03 (complex signal, 2 H, H34),
2J(H,P)=14.5 Hz, J(H14,H15)=7.5 Hz, 2 H, H14), 1.99
3
3
1.92 (d, J(H11%,H12%)=6.5 Hz, 3 H, H12%), 1.77 (complex
(complex signal, 2 H, H34), 1.85 (complex signal, 1 H,
H17), 1.73 (complex signal, 2 H, H27), 1.52 (complex
signal, 2 H, H27), 1.61 (complex signal, 1 H, H17),

1996
E. Dura´n et al. / Tetrahedron: Asymmetry 12 (2001) 1987–1997
signal, 1 H, H18a), 1.40 (complex signal, 3 H, H18b
+
monochromatized Mo Ka radiation was used. Cell
constants were obtained from least-squares refinement
using the setting angles of 6085 reflections. The system
was determined to be monoclinic, space group C2.
Lorentz-polarization correction was applied. The struc-
ture was resolved using the SHELXS software
package55 and refined by least-squares using the com-
plete matrix with the SHELXL software package.56 The
H28), 1.26 (complex signal, 10 H, H29–33), 1.03 (dt,
3
3J(H,P)=19.0 Hz, J(H14,H15)=7.5 Hz, 3 H, H15), 0.98
(complex signal, 3 H, H20), 0.91 (t, 3J(H18,H19)=7.5
Hz, 3 H, H19) ppm; 13C NMR (75 MHz, CDCl3, 25°C):
l=164.34 (d, 4J(C,P)=1.7 Hz, CꢂO), 161.18 (d,
3J(C,P)=13.3 Hz, C3), 156.83 (s, C25), 146.12 (d,
2J(C,P)=20.4 Hz, C11), 143.92 (s, C22), 139.01 (s,
1
2
2 2
C35H), 135.18 (s, C8H), 134.18 (d, J(C,P)=99.3 Hz,
refined function was ꢀꢀ(ꢁFoꢁ −ꢁFcꢁ ) , where ꢀ=[|2(I)+
C13), 131.40 (d, 1J(C,P)=117.9 Hz, C12), 130.92 (d,
(0.1206P)2]−1, P=(ꢁFoꢁ +2ꢁFcꢁ )/3. f, f % and f ¦ values
were taken from International Tables of X-ray Crystal-
lography.57 The chirality of the structure was defined
with Flack coefficient.58 After isotropic refinement a
difference map showed the presence of one ethyl acetate
and one water molecule in the structure. Atom posi-
tions were calculated and refined with a global temper-
ature factor. Crystallographic data (excluding structure
factors) for the structure in this paper have been
deposited with the Cambridge Crystallographic Data
Centre as supplementary publication number CCDC-
150264. Copies of the data can be obtained, free of
charge, on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK [fax: +44(0)-1223-336033 or
e-mail: deposit@ccdc.cam.ac.uk].
2
2
3
2J(C,P)=10.3 Hz, C6H), 128.74 (d, J(C,P)=10.9 Hz,
C7), 123.46 (d, 3J(C,P)=11.4 Hz, C1H), 122.10 (s,
C23H), 120.27 (d, 3J(C,P)=9.6 Hz, C9H), 119.92 (s,
2
C2H), 114.95 (s, C24H), 114.52 (d, J(C,P)=10.2 Hz,
C4H), 113.99 (s, C36H2), 73.30 (s, C16H2), 68.24 (s,
C26H2), 34.47 (s, C17H), 33.67 (s, C34H2), [29.36, 29.26,
29.21, 29.11, 28.95, 28.76] (s, C27H2+C29–33H2), 25.90 (s,
C18H2+C28H2), 22.98 (d, 1J(C,P)=70.4 Hz, C14H2),
2
16.32 (s, C20H3), 11.13 (s, C19H3), 6.05 (d, J(C,P)=4.2
Hz, C15H3) ppm; 31P NMR (121 MHz, CDCl3,
P(OMe)3): l=44.72 (s) ppm; MS (10 kV, positive FAB,
Cs, NBA): m/z: 603 [M]+; HRMS (70 eV, CI, CH4):
m/z: 603.3236 [M+H]+, C37H48O5P requires 603.3239;
HPLC (CSP-150 phase, heptane–iso-propanol 9:1, 1
mL/min, 40 bar, 254 nm) t1=17.119 min (R,S)-1c,
t2=19.603 min (S,S)-1c, t0=1.486 min, ꢀ1=1.611 min,
ꢀ2=1.913 min, k%=10.52, k%=12.19, h=1.16, RS=
Acknowledgements
2
1.41, 99% of (S,S)1-1c.
3.12. Discoordination of (R,R,S)-4c and oxidation of
(S,S)-2c to obtain (SC,RP)-5-ethyl-3-(2-methylbutoxy)-
7-(4-undec-10-enoxyphenoxycarbonyl)-5H-dibenzophos-
phole 5-oxide (R,S)-1c
This research was supported by the Spanish Ministerio
de Educacio´n y Cultura, grant PB96-1491, and the
Generalitat de Catalunya, grant 1996SGR 00094. Dr.
E. Dura´n thanks the Departament d’Universitats,
Recerca i Societat de la Informacio´ de la Generalitat de
Catalunya for a fellowship.
(RC11%,RP,SC17) - [1 - (1 - Aminoethyl)naphthyl - C2,N]-
[chloro][5-ethyl-3-(2-methylbutoxy)-7-(4-undec-10-enoxy-
phenoxycarbonyl)-5H-dibenzophosphole-P]palladium-
(II) (R,R,S)-4c (227 mg, 0.25 mmol) was dissolved in
anhydrous tetrahydrofuran (50 mL), and 1,2-bis-
(diphenylphosphino)ethane (110 mg, 0.28 mmol) was
added to the solution. The resulting mixture was stirred
at rt under an inert atmosphere for 3 h. The solution
was evaporated, the residue dissolved in benzene and
filtered through Celite. 30% H2O2 (1 mL) was added
and the solution was stirred for another 2 h. Then,
dichloromethane (100 mL) and water (100 mL) were
added. The organic layer was extracted, dried and the
solvent removed. The residue was purified by column
chromatography eluting with AcOEt, yielding (SC,RP)-
5-ethyl-3-(2-methylbutoxy)-7-(4-undec-10-enoxyphen-
oxycarbonyl)-5H-dibenzophosphole 5-oxide (150 mg,
99%) as a yellow solid with all spectra identical to
(S,S)-1c; HPLC (CSP-150 phase, heptane–iso-propanol
9:1, 1 mL/min, 40 bar, 254 nm) t1=17.119 min (R,S)-
1c, t2=19.603 min (S,S)-1c, t0=1.486 min, ꢀ1=1.611
min, ꢀ2=1.913 min, k%=10.52, k%=12.19, h=1.16,
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