Water soluble phosphines Part XV. Syntheses of multiply functionalized and chiral phospine ligands by Pd-catalyzed P-C and C-C coupling reactions

Article abstract of DOI:10.1016/S0022-328X(01)01371-7

Phosphine ligands containing mono- and multiply substituted aromatic substituents (1-13, 19a and 19b) are accessible in high yields by palladium-catalyzed P-C coupling reactions between primary, secondary or disecondary phosphines and iodo- or bromoaromatic compounds. The reaction is of broad applicability and compatible with electron donor or electron acceptor substituents in ortho, meta or para position to the halogen in the aromatic ring systems. It may be performed in protic and aprotic solvents. The chiral spirocyclic boronato complex 15a is formed upon reaction of 3 with boric acid, while with benzeneboronic acid 15c with a peripheral Lewis acid group is obtained. The Pd-mediated P-C coupling reaction of primary phosphines proceeds stepwise, tailor-made chiral secondary (16) and tertiary phosphines (17) being formed in high yield. Through combination with Suzuki-type C-C coupling reactions, the scope of Pd-catalyzed P-C coupling may be extended further, novel ligands (20a, 20b, 21a, 21b) with biphenylyl substituents being accessible. The X-ray structures of the salicylic acid derivative 3 (space group P1) and of ortho-iso-propylphenyl-diphenylphosphine 6 (space group Pbca) have been determined.

Full text of DOI:10.1016/S0022-328X(01)01371-7

Journal of Organometallic Chemistry 645 (2002) 14–26
www.elsevier.com/locate/jorganchem
Water soluble phosphines
Part XV. Syntheses of multiply functionalized and chiral
phosphine ligands by Pd-catalyzed PꢀC and CꢀC coupling
reactionsꢀ
David J. Brauer a, Martin Hingst a, Konstantin W. Kottsieper a, Christian Liek a,
Thomas Nickel a, Michael Tepper a, Othmar Stelzer a,*, William S. Sheldrick b
a Fachbereich 9, Anorganische Chemie, Bergische Uni6ersita¨t, Gaußstr. 20, D-42097 Wuppertal, Germany
b Lehrstuhl fu¨r Analytische Chemie, Ruhr-Uni6ersita¨t Bochum, Uni6ersita¨tsstr. 150, D-44780 Bochum, Germany
Received 24 April 2001; accepted 25 September 2001
Abstract
Phosphine ligands containing mono- and multiply substituted aromatic substituents (1–13, 19a and 19b) are accessible in high
yields by palladium-catalyzed PꢀC coupling reactions between primary, secondary or disecondary phosphines and iodo- or
bromoaromatic compounds. The reaction is of broad applicability and compatible with electron donor or electron acceptor
substituents in ortho, meta or para position to the halogen in the aromatic ring systems. It may be performed in protic and aprotic
solvents. The chiral spirocyclic boronato complex 15a is formed upon reaction of 3 with boric acid, while with benzeneboronic
acid 15c with a peripheral Lewis acid group is obtained. The Pd-mediated PꢀC coupling reaction of primary phosphines proceeds
stepwise, tailor-made chiral secondary (16) and tertiary phosphines (17) being formed in high yields. Through combination with
Suzuki-type CꢀC coupling reactions, the scope of Pd-catalyzed PꢀC coupling may be extended further, novel ligands (20a, 20b,
(
21a, 21b) with biphenylyl substituents being accessible. The X-ray structures of the salicylic acid derivative 3 (space group P1) and
of ortho-iso-propylphenyl-diphenylphosphine 6 (space group Pbca) have been determined. © 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Phosphine ligand synthesis; Pd-catalyzed PꢀC and CꢀC coupling; Consecutive reactions; Functionalized chiral phosphines; Biphenylyl
substituents; X-ray structures
[5a,5b] and Hirao et al. [5c]. Imamoto et al. [5d,5e]
employed BH3-protected secondary phosphines for the
synthesis of mono- and bidentate ligands by Pd-assisted
PꢀC coupling reactions. The reactive intermediate of
these reactions has been identified very recently [5f].
Due to side reactions at the PꢀBH3 unit, these elegant
coupling reactions cannot, however, be applied for the
synthesis of phosphine ligands A bearing reactive func-
tional groups (OH, COOH, SO3−). As shown by us
before [6a], unprotected primary and secondary phos-
phines may be employed directly in PꢀC cross-coupling
with functional arylhalides using a range of polar and
non-polar solvents and even in aqueous two-phase sys-
tems [7].
1. Introduction
Since the early work of Heck [2,3] in the 1960s,
palladium-catalyzed coupling reactions have been de-
veloped as an important synthetic methodology for the
carbon–heteroatom bond formation. Thus, arylamines
are accessible in high yields by Pd-catalyzed CꢀN cross-
coupling between secondary amines and arylhalides [4].
Carbonꢀphosphorus bond formation between phosphi-
nates or dialkylphosphites and aromatic halides em-
ploying Pd catalysts have been reported by Xu et al.
ꢀ For Part 14 of this series see Ref. [1].
* Corresponding author. Tel.: +49-202-439-2517; fax: +49-202-
439-3053.
In order to demonstrate the broad applicability of
Pd-catalyzed PꢀC coupling reactions in ligand synthe-
E-mail address: stelzer@uni-wuppertal.de (O. Stelzer).
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01371-7

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
15
may be achieved by combining Pd-catalyzed PꢀC and
CꢀC cross-coupling reactions (e.g. Suzuki-type reac-
tions) in a reaction scheme according to Eq. 3a and 3b
(Scheme 1). Bromophenylphosphines, e.g. D [8], which
are easily accessible by Pd-catalyzed PꢀC coupling reac-
tions, may be employed as intermediate products (Eq.
3a) for the syntheses of bulky and chiral biphenyl-sub-
stituted phosphine ligands (E).
sis, we report on further examples employing polyfunc-
tional arylhalides with substituents of variable elec-
tronic properties in different positions of the aromatic
ring systems as substrates. Using primary phosphines as
starting materials, consecutive replacement of the hy-
drogen atoms by these reactions should offer an easy
access to novel chiral and multiply functionalized phos-
phines B, C (Eq. 2a and 2b). Part of this work has
appeared in a preliminary report elsewhere [6b].
Further exploitation of this synthetic methodology
2. Syntheses of poly- and heterofunctional phosphine
ligands
Among the various methods for the syntheses of
tertiary phosphine ligands bearing functionalized aro-
matic substituents, nucleophilic phosphination of
fluoroaromatic compounds and Pd-catalyzed cross-cou-
pling of primary and secondary phosphines with
iodoaromatic compounds are the most favorable proce-
dures. In both cases, no introduction of protection
groups at the functionalities and at phosphorus is nec-
essary, as reported for the syntheses using Grignard [9a]
or organozinc reagents [9b,9c]. While the nucleophilic
phosphination reaction of fluoroaromatic compounds
requires the activation of the CꢀF bond by electron-
withdrawing substituents in ortho or para position [10],
this is not a prerequisite for Pd-catalyzed PꢀC cross-
coupling, as shown by us very recently [6].
Scheme 1.
Thus, derivatives 1–3 [6b] of 2- or 4-diphenylphos-
phinophenol with COOH substituents in ortho, meta or
para position to the OH groups are accessible by this
route using Pd(OAc)2 as the catalyst (Eq. 4–6). These
cross-coupling reactions may also be employed to elec-
tron-rich substrates, as shown by the synthesis of
the known phosphines 2-diphenylphosphinophenol
[11a,11b], 2-diphenylphosphinoaniline [11c] and 2-
diphenylphosphinobenzylalcohol (4). They are formed
under almost identical conditions as 1–3 in good to
satisfying yields (Eq. 7, Scheme 2). For a further purifi-
cation of 4, it was transformed to its trimethylsilylether
by reaction with HN(SiMe3)2, which, in contrast to 4,
could be distilled in vacuo without decomposition. De-
protection of the silylether with NEt4F yields pure 4.
This ligand was obtained in a multistage synthesis by
reduction of 2-diphenylphosphinobenzoic acid or 2-
(diphenylphosphino)benzaldehyde [11d,11e].
Pd-catalyzed PꢀC cross-coupling reactions are even
compatible with peptide units, as shown by the synthe-
sis of the chiral phosphine ligand 5 ([h]2D0= +14.9°,
c=1.0, CHCl3) (Eq. 8). The starting material, 2-
iodobenzoic acid (R)-(+)-phenylethylamide (5a), was
obtained by reaction of 2-iodobenzoic acid chloride
(prepared from of 2-iodobenzoic acid and SOCl2) with
(R)-(+)-1-phenylethylamine. The Pd-mediated cou-
pling reaction is not hampered by the bulky
COꢀNHꢀCH(Me)Ph substituent. The same applies for
Scheme 2.

16
D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
In summary, these results indicate that Pd-catalyzed
cross-coupling reactions as developed by us are of
broad applicability, the electronic nature, number and
position of the substituents in the iodoaromatic sub-
strates being of no significant influence on the yields
and reaction rates by which the multiply functionalized
phosphine ligands are formed (Plate 1).
Plate 1.
The scope of this reaction may be further extended to
dialkylphosphines, as shown by Hillhouse [13a] for
some reactions of diisobutylphosphine with non-func-
tionalized aromatic compounds, such as 4-bromoben-
zene, 4-bromotoluene and 1-bromonaphthalene.
Primary alkylphosphines, like i-butylphosphine, may
selectively be arylated with iodobenzene to yield the
chiral secondary phosphine 14 (Eq. 17). Due to the
presence of two centers of chirality (a-C, P), 14 is
obtained as a mixture of two diastereoisomers (ery-
thro–threo). 14 has been obtained alternatively by alky-
lation of PhPH2 with 2-bromo-butane in the superbasic
medium DMSO–KOH, H2O [13b].
Ligands 1–14 have been identified by their 31P{1H}-,
1H- and 13C{1H}-NMR spectra. The assignment of the
signals of the aromatic carbon atoms in the 13C{1H}-
NMR spectra was achieved by comparison with the
corresponding data of Ph3P [14] and its derivatives
bearing functional groups [6a,8,10]. Further support
was gained from intensity arguments, DEPT-13C-NMR
spectra and the relative magnitude of the coupling
n
constants J(PꢀC). The indication of the carbon atoms
used for 1–14 is shown in Scheme 2.
Scheme 3.
3. Boric acid and benzeneboronic acid derivatives of 3
the bulky iso-propyl group in the ortho position to the
halogen of the aromatic ring system in 6a during the
synthesis of 6 (Eq. 9). Achiral phosphine amide ligands
related to 5 have been obtained by Hedden and Round-
hill [12] in moderate yield using ortho-(diphenylphos-
phino)benzoic acid as the starting material.
While Pd-assisted coupling of ortho-, meta- and
para-bromoiodobenzene with Ph2PH gave selectively
the corresponding bromophenylphosphines (see Eq. 22
below and Ref. [8]), with 1,4-diiodobenzene only a
mixture of 4-iodophenyl-diphenylphosphine (7) and
1,4-bis(diphenylphosphino)benzene (7a) [11f] was ob-
tained (Scheme 2, Eq. 10). As a reactive derivative of
Ph3P, the iodophenylphosphine 7 is of potential interest
in ligand synthesis.
Ligands of type 1 in which the OH group is replaced
by a Me substituent (e.g. 8) may be obtained by the
procedure reported here as well (Eq. 11). This method
is also applicable for the high yield synthesis of phos-
phine ligands (9, 10 [6b], 11–13) containing aromatic
groups with two or three substituents of identical or
different electronic properties (OH, COOH, SO3H) (Eq.
12–16).
Like 2-diphenylphosphinophenol [11a], phosphines 1,
2, 4, 11–13 are of interest as hemilabile P, O-chelating
ligands [15a,15b]. Phosphine ligand 3 combines the
donor properties of a Ph2P group with the chelating
potential of the salicylic acid moiety [15c]. It reacts with
boric acid in the presence of tetraethylammonium hy-
droxide to give the boric acid disalicylate complex 15a
(Eq. 18a, Scheme 3). Complex formation between sali-
cylic acid and boric acid has been studied by Meulenhoff
in the 1920s [16a,16b] and later by others in detail
[16c,16d]. The complexes formed contain tetrahedral-co-
ordinated boron in a spiro-type structure and they are
stable towards dissociation. Due to the presence of a
chiral boron atom [17] in 15a, the phenyl groups of the
Ph2P units are diastereotopic, two sets of resonances
being observed in the 13C{1H}-NMR spectrum for
C7ꢀC10 (for an indication of the carbon atoms see
Scheme 3). Compounds of type 15a represent a novel
type of bidentate phosphine ligands with the donor
groups kept in fixed distance by a rigid chiral spacer unit.
With [RhCl(NBD)]2 (NBD=bicyclo[2.2.1]hepta-2,5-di-
ene) [18], 15a forms a bimetallic complex 15b (Eq. 18b)

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
17
Like the C2 symmetric boron analog of DIOP (F)
reported by Kagan et al. [19a] and Jacobsen et al. [19b],
complexes of ligands of type 15c may serve as possible
templates for directing catalytic reactions by precoordi-
nation of donor-functionalized substrates. The regiose-
lective hydroformylation of allylacetate by zwitterionic
Rh complexes of 1,4-bis(diphenylphosphino)butane
containing the bis[2-hydroxybenzoato(2−)ꢀO1O2]-
borate (−1) anion (G) yields the linear aldehyde in a
93:7 selectivity [20]. Phosphine ligands (H) containing
the 1,3,2-dioxaborinane skeleton have been recently
reported by Balueva et al. [21].
showing a doublet at l=32.0 due to RhꢀP coupling
(JRhꢀP=171.1 Hz) in the 31P{1H}-NMR spectrum. As
in the free ligand, the Ph groups of the Ph2P moieties
are diastereotopic, two resonances being observed in
the 13C{1H}-NMR spectrum for C7ꢀC10.
On reaction of benzeneboronic acid with the phos-
phine ligand 3 containing a salicylic acid moiety in
dichloromethane, the cyclic boronic ester 15c is formed
(Eq. 18c). The mass spectrum of 15c shows two peaks
for the molecular ion at m/e 408 (11B) and 407 (10B)
with the expected intensity ratio.
4. X-ray structure of 3 and 6
By recrystallization of 3 from CH2Cl2 crystals of
composition C19H15O3P suitable for X-ray structural
analysis could be obtained. The results are shown in
Fig. 1, selected bond lengths and bond angles are given
in the caption to Fig. 1.
In the solid state, the molecules of 3 are arranged in
columns that are interconnected by hydrogen bridging
between the COOH substituents. As in salicylic acid
[22a], the OH groups of 3 are engaged in intramolecular
hydrogen bonds building a very common motive of
intramolecular hydrogen bridging [22c].
,
Fig. 1. Molecular structure of 3. Selected interatomic distances (A)
and angles (°): PꢀC(11) 1.836(2), PꢀC(21) 1.832(2), PꢀC(31) 1.834(2),
C(1)ꢀO(1) 1.234(2), C(1)ꢀO(2) 1.309(2), C(14)ꢀO(3) 1.352(3),
C(1)ꢀC(13) 1.459(3), C(11)ꢀC(12) 1.379(3), C(12)ꢀC(13) 1.397(3),
C(13)ꢀC(14) 1.401(3), C(14)ꢀC(15) 1.381(3), C(15)ꢀC(16) 1.372(3),
C(16)ꢀC(11) 1.399(3), C(11)ꢀPꢀC(21) 102.44(10), C(11)ꢀPꢀC(31)
100.78(9), C(21)ꢀPꢀC(31) 101.16(10), O(1)ꢀC(1)ꢀO(2) 121.98(18),
O(2)ꢀC(1)ꢀC(13) 114.88(18), O(1)ꢀC(1)ꢀC(13) 123.13(18).
The hydrogen bridging motive found in the solid
state of 3 is typical for carboxylic acids [22b,22d], and
different CꢀO bond lengths are observed (e.g. 1.25 and
,
1.36 A in HCOOH dimers) [23]. In 3, the car-
,
bonꢀoxygen distances are C(1)ꢀO(1)=1.234(2) A and
,
C(1)ꢀO(2)=1.309(2) A, the O(1)ꢀC(1)ꢀO(2) bond angle
being 121.98(18)°. The PꢀC bond lengths and CꢀPꢀC
bond angles do not differ significantly from the corre-
sponding values found for Ph3P [24], the phenyl groups
are orientated in a propeller-type arrangement (dihedral
angles C(11)ꢀPꢀC(31)ꢀC(36)= −94.86(19)°, C(31)ꢀPꢀ
C(21)ꢀC(26)= −77.08(19)°, C(21)ꢀPꢀC(11)ꢀC(16)=
−97.76(19)°). The oxygen atoms O(1) and O(2) of the
COOH substituent are almost coplanar with the aro-
matic ring system C(11)ꢀC(16). As a consequence of the
interaction between O(3) and O(1), the bond length
,
C(14)ꢀO(3) is 1.352(3)
A and the bond angles
C(13)ꢀC(1)ꢀO(1) and C(13)ꢀC(14)ꢀO(3) are widened up
to 123.13(18) or 122.75(20)°, respectively.
Crystals of 6 suitable for X-ray structural analysis
could be obtained by recrystallization from ethanol.
The results are shown in Fig. 2 with selected bond
lengths and bond angles given in the caption. As in 3,
the PꢀC bond lengths and PꢀCꢀP bond angles may be
compared well with the corresponding values found for
Ph3P [24]. The i-Pr substituent in the ortho position
does not significantly influence the geometry of the PC3
skeleton. The planes defined by the aromatic carbon
atoms of each aryl ring are rotated in the same sense
,
Fig. 2. Molecular structure of 6. Selected interatomic distances (A)
and angles (°): PꢀC(11) 1.836(2), PꢀC(21) 1.832(2), PꢀC(31) 1.834(2),
C(1)ꢀO(1) 1.234(2), C(1)ꢀO(2)1.309(2), C(14)ꢀO(3) 1.352(3),
C(1)ꢀC(13) 1.459(3), C(11)ꢀC(12) 1.379(3), C(12)ꢀC(13) 1.397(3),
C(13)ꢀC(14) 1.401(3), C(14)ꢀC(15) 1.381(3), C(15)ꢀC(16) 1.372(3),
C(16)ꢀC(11) 1.399(3), C(11)ꢀPꢀC(21) 102.44(10), C(11)ꢀPꢀC(31)
100.78(9), C(21)ꢀPꢀC(31) 101.16(10), O(1)ꢀC(1)ꢀO(2) 121.98(18),
O(2)ꢀC(1)ꢀC(13) 114.88(18), O(1)ꢀC(1)ꢀC(13) 123.13(18).

18
D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
against the phosphorus substituent plane defined by the
atoms C(1), C(10) and C(16). Furthermore, the angle
formed by the isopropyl substituted ring (48.9(2)°) lies
between the values found for the two phenyl groups
(44.6(1) and 51.6(1)°). The isopropyl group is located
on the phosphorus side of its above-mentioned sub-
stituent plane. This orientation directs the bulky sub-
stituent away from the pseudo-threefold axis of the
molecule and thus reduces the steric congestion between
the groups bonded to the phosphorus atom. This seems
to be the preferred conformation of the C6H4ꢀ2-i-Pr
group with respect to the PꢀC(1) rotational axis also in
solution as indicated by the large coupling constant
2J(PꢀC) (23.4 Hz) observed for ortho-carbon atom bear-
ing an isopropyl substituent (C(2)) in the 13C{1H}-
A mixture of tris(dibenzylideneacetone) dipalladium
chloroform adducts and 1,3-bis(phenylphosphino)-
propane in a 1:1 molar ratio was used as the catalyst. In
their synthesis of secondary phosphines, Beletskaya et
al. [5g] used the elusive silylphosphines RP(H)SiMe3 in
a Stille-type coupling reaction. This method suffers
from the reactivity of the PꢀSi bond towards polar
substituents such as OH, NH2, COOH in the substrate
molecules. By standard methods, these multifunctional
ligands are accessible only in low yield multistage syn-
theses using protective groups. Functionalized sec-
ondary phosphines are valuable starting materials for
the syntheses of chiral tertiary phosphine ligands as
exemplified by the successful preparation of 17 by
consecutive Pd-catalyzed PꢀC coupling reactions. Lig-
ands of type 16 and 17 are of great potential in parallel
syntheses [28a] and combinatorial catalysis [28b].
Ligand tailoring by Pd-catalyzed PꢀC coupling reac-
tions can also be achieved using disecondary phosphi-
nes as starting materials. Thus, the P2N2 hybrid ligand
18 [29] with ortho-aminophenyl substituents was ob-
tained in high yield by coupling 1,2-diphenylphos-
phinopropane (accessible by standard techniques) with
ortho-iodoaniline using Pd(OAc)2 as the catalyst (Eq.
21). The bidentate ligands (18 and 18a) obviously do
not deactivate the catalyst system by formation of
stable Pd(0) chelate complexes in this reaction. 18 was
obtained as a 1:1 mixture of two diastereoisomers I
(l= −34.2) and II (l= −34.3). On recrystallization
from methanol, an enrichment of diastereoisomer I in a
8:3 ratio was achieved. In the 13C{1H}-NMR spectrum,
the two diastereoisomers show first-order triplets for
the center carbon atom of the CH2ꢀCH2ꢀCH2 bridge,
while overlapping higher-order pattern (X part of a
ABX spectra; X=13C; A, B=31P) are observed for all
other carbon atoms with exeption of those in para-posi-
tion to phosphorus within the aromatic ring systems for
which only singlets are obtained.
2
NMR spectrum of 6. In general, J(PꢀC) is large when
the lone pair is close to the C atom, and it is small
when remote [25–27]. The latter applies for the unsub-
stituted ortho-carbon atom C(6), for which no PꢀC
coupling fine structure was observed in the 13C{1H}-
NMR spectrum.
5. Syntheses of functionalized chiral secondary and
tertiary phosphine ligands by consecutive Pd-catalyzed
PꢀC coupling reactions
Pd-catalyzed PꢀC coupling reactions of primary
phosphines, e.g. PhPH2, with arylhalides in a 1:2 stoi-
chiometry afford highly functionalized tertiary phosphi-
nes, secondary phosphines being formed in
a
consecutive reaction as intermediates [6,7]. If, however,
equimolar amounts of the reactants are employed,
functionalized chiral secondary phosphine ligands, e.g.
16, may selectively be obtained in high yields (Eq. 19).
The P2N2 hybrid ligand I related to 18 has been
synthesized very recently by us using nucleophilic phos-
phination reaction using 2-phenylphosphino benzyl-
amine as starting material (Scheme 4) [1].
6. Synthesis of phosphine ligands by combination of
Pd-catalyzed PꢀC and CꢀC coupling reactions
As shown for the chiral ligand 17 in this paper (Eq.
19 and 20) and for the phosphonato phosphines J [8]
reported earlier by us, consecutive Pd-catalyzed PꢀC
coupling reactions may be used for a systematic tailor-
ing of phosphine ligands. Combination of PꢀC and
CꢀC cross-coupling reactions should extend the scope
of metal-mediated ligand synthesis considerable.
Since the work reported here was also directed to-
wards the syntheses of aromatic phosphines bearing
Scheme 4.

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
19
aryl substituents in ortho-position to phosphorus, we
have chosen the bromophenylphosphines 19a [30] and
19b as starting materials (Scheme 5). They are easily
accessible in high yields by Pd-catalyzed PꢀC coupling
between ortho-bromoiodobenzene with phenyl- or
diphenylphosphine. Pd(Ph3P)4 was employed as the cat-
alyst in this reaction (Eq. 22 and 24). Introduction of
the aryl substituents was achieved by Suzuki-type reac-
tions [31] with ortho- or para-tolylboronic acid (Eq. 23
and 25). The ligands 20a, 20b and 21a, 21b containing
2-biphenylyl substituents are formed in low to satisfy-
ing yields. While 20a, 20b (l= −11.7, −12.3) and 21b
(l= −18.8) show only one signal in the 31P{1H}-NMR
spectrum, three resonances are observed for 21a (l=
−17.1, −20.1, −20.2), indicating the presence of
three diastereoisomers (one racemate and two meso-
forms) for 21a with two axially chiral biphenylyl sub-
stituents as shown schematically in Fig. 3. This
interpretation is supported by the observation of four
13C{1H}-NMR resonances for the ortho-methyl groups
of the tolyl substituents. Two of them may be assigned
to the meso-forms I and II with equivalent ortho-
methyl groups. In case of the racemate the ortho-methyl
groups or the ipso-carbon atoms are inequivalent. A
similar situation is met with the disecondary butylphos-
phine (secBu)2PH with two centers of asymmetry at the
a-carbon atoms. As in the case of 21a three resonances
are observed in the 31P{1H}-NMR spectrum [32].
The mass spectrum of 21a shows the M+ peak at m/e
at 442 (63%), the basis peak corresponding to the
fragment ion M+ꢀCH3ꢀH (m/e=426).
Due to the presence of an element of axial chirality
the two phenyl groups of the PPh2 substituent in 20a
are chemically non-equivalent. As a result of partial
overlap of the 20 signals to be expected for the aro-
matic carbon atoms, only 19 are observed in the
13C{1H}-NMR spectrum of 20a. In the para-isomer
20b, however, the Ph groups of the PPh2 substituent are
enantiotopic. Therefore, only a total of 14 resonances
appears in the 13C{1H}-NMR spectrum for the aro-
matic carbon atoms.
Phosphines of type 21a with two axially chiral sub-
stituents have to the best of our knowledge not been
reported in the literature before. They are of interest as
starting materials for the syntheses of chiral bulky
water-soluble phosphines by direct sulfonation with
oleum [33].
7. Experimental
For experimental details, see part 14 of this series [1].
Phenylphosphine, diphenylphosphine [34a,34b], 1,3-
bis(phenylphosphino)propane [34c,34d] and Pd(Ph3P)4
[34e] were synthesized by known methods. The iodo
compounds 3a, 4a, 6a and 8a were purchased from
Aldrich GmbH, Fluka and Lancaster Syntheses, while
1a, 2a, 9a and 13a have been obtained in a Sandmeyer-
type reaction using the corresponding commercially
available anilines as starting materials [35]. 5-Amino-3-
sulfobenzoic acid and 3-amino-2-hydroxy-5-sulfoben-
zoic acid for the syntheses of 9a and 13a have been
donated by the Bayer AG. 2-Butylphosphine was a gift
of Clariant GmbH. Bromohemimellitic acid 10a was
prepared according to the literature procedure [36]. 11a
and 12a were synthesized by direct iodination of 4-hy-
droxyisophthalic acid or 2-hydroxy-5-methyl benzoic
acid, respectively, with iodine/silver sulfate [37]. Tris-
(dibenzylideneacetone) dipalladium chloroform adduct,
benzene boronic acid, ortho- and para-toluene boronic
acid have been purchased from Aldrich GmbH. The
Scheme 5.
1
starting materials were characterized by H-, 13C{1H}-
and 31P{1H}-NMR spectroscopy and mass spectrome-
try. 1H-, 13C{1H}- and 31P{1H}-NMR spectra were
recorded on a Bruker AC 400 or AM 250 and a JEOL
FX90 Q Fourier transform spectrometer, mass spectra
were obtained on a Varian MAT 311A.
Fig. 3. Diastereoisomers of 21a.

20
D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
Table 1
Synthesis of 1–3, 8, 11, 12
Iodo
Ph2PH (g
NEt3 (g
(mmol))
CH3CN (ml)
Pd(OAc)2 (mg Reaction
KOH ((1n) ml) Yield (g (%))
compounds (g (mmol))
(mmol))
(mmol))
conditions
1
2
3
8
1.32 (5) 1a
13.2 (50) 2a
2.08 (7.9) 3a
9.85 (37.6) 8a
0.93 (5)
1.02 (10)
10.2 (100)
1.6 (16)
8.1 (80)
12.1 (120)
20.2 (200)
10
100
30
90
90
1.1 (5)
5.6 (25)
2.0 (9)
8.5 (38)
8.5 (38)
22.5 (100)
48 h, 90 °C
18 h, 100 °C
12 h, 85 °C
18 h, 90 °C
40 h, 85 °C
48 h, 90 °C
10
100
16
80
120
120
0.8 (49)
10.6 (66)
1.7 (67)
7.3 (61)
9.4 (68)
22.2 (66)
9.31 (50)
1.47 (7.9)
7.0 (37.6)
7.0 (37.7)
11 11.6 (37.7) 11a
12 27.8 (100) 12a 18.6 (100)
250
7.1. General procedure for the syntheses of 1–3, 8, 11,
12
H); 13C{1H}-NMR (d6-DMSO, l): (C1ꢀC10) 126.6
(10.1), 136.6 (24.3), 118.6 (6.1), 162.6, 114.4 (9.1), 141.0
(19.2), 137.5 (11.1), 133.6 (19.2), 129.3 (6.1), 129.5,
172.0 (COOH); 31P{1H}-NMR (d6-DMSO, l): −6.6.
8, Anal. Found: C, 74.63; H, 5.50. C20H17O2P
(320.3). Calc.: C, 74.99; H, 5.35%. MS: m/e 320 [M+].
1H-NMR (d6-DMSO, l): 11.6 (COOH), 2.3 (CH3),
7.1–8.0 (arom. H); 13C{1H}-NMR (d6-DMSO, l):
(C1ꢀC10) 136.4 (14.1), 146.6 (25.3), 129.8, 133.0, 128.7,
130.5 (4.1), 135.0 (10.2), 133.6 (19.9), 129.0 (7.1), 129.3,
167.0 (COOH), 20.9 (20.4, CH3); 31P{1H}-NMR (d6-
DMSO, l): −11.1.
11, Anal. Found: C, 65.81; H, 4.27. C20H15O5P·
(366.3). Calc.: C, 65.58; H, 4.13%. MS: m/e 366 [M+].
1H-NMR (d6-DMSO, l): 7.1–8.5 (arom. H); 13C{1H}-
NMR (d6-DMSO, l): (C1ꢀC10) 126.4 (7.2), 166.5
(16.7), 112.6, 133.6, 122.5, 140.1, 135.7 (11.1), 134.0
(20.2), 129.1 (7.1), 129.4, 166.6 (COOH), 172.4
(COOH); 31P{1H}-NMR (d6-DMSO, l): −15.8.
12, Anal. Found: C, 69.73; H, 5.33. C20H17O3P·
0.5H2O (345.3). Calc.: C, 69.57; H, 5.24%. MS: m/e
336.6 [M+]. 1H-NMR (d6-DMSO, l): 10.2 (COOH),
2.2 (CH3), 6.8–7.9 (arom. H); 13C{1H}-NMR (d6-
DMSO, l): (C1ꢀC10) 126.0 (15.2), 161. 5 (16.2), 110.5
(2.8), 131.5, 141.6, 136.6 (9.1), 133.8 (20.2), 128.5 (7.1),
128.9, 174.9 (1.5, COOH), 20.4 (CH3); 31P{1H}-NMR
(d6-DMSO, l): −15.6.
The iodoaromatic compounds, diphenylphosphine,
triethylamine and the corresponding amounts of the
catalyst Pd(OAc)2 were dissolved in acetonitrile. The
amounts of the reactants are collected in Table 1.
Traces of oxygen dissolved in the solutions were re-
moved by three freeze–thaw cycles using purified nitro-
gen as inert gas. The reaction mixtures were then
heated to 85–100 °C for several hours. Completion of
the reactions was checked by 31P{1H}-NMR spec-
troscopy. After cooling, the reaction mixtures to ambi-
ent temperature all volatiles were removed in vacuo
(30 °C, 1 mbar). The residues were dissolved in 1 N
KOH and the solutions were washed with two aliquots
of diethylether and petrolether (40/60). The aqueous
solution was cooled to 5 °C, and 2 N HCl was added
until a pH value of 2 was reached. The precipitate
formed was filtered off, dissolved in diethylether and
the solution was dried over magnesium sulfate. The
residue obtained after evaporation of the solvent in
vacuo (30 °C, 1 mbar) was recrystallized from CH2Cl2
or ethanol–water mixtures. Yields are given in Table 1.
1, Anal. Found: C, 69.34; H, 4.84. C19H15O3P·
0.5H2O (331.3). Calc.: C, 68.88; H, 4.87%. MS: m/e 322
[M+]. 1H-NMR (d6-DMSO, l): 12.4 (COOH), 10.6
(OH), 7.6–7.2 (arom. H); 13C{1H}-NMR (d6-DMSO,
l): (C1ꢀC10) 123.2 (14.2), 163.2 (16.2), 114.6, 132.2,
121.9, 135.0, 136.1 (12.1), 133.4 (20.2), 128.6 (7.1),
128.8, 166.9 (COOH); 31P{1H}-NMR (d6-DMSO, l):
−15.5.
7.2. Synthesis of 4
5.34 g (28.7 mmol) of diphenylphosphine and 6.72 g
(28.7 mmol) of 2-iodobenzyl alcohol were dissolved in
40 ml of N,N-dimethylacetamide. To this solution, 2.94
g (30.0 mmol) of KOAc and 2.9 ml of a Pd(OAc)2 stock
2, Anal. Found: C, 68.68; H, 4.96. C19H15O3P·
0.5H2O (331.3). Calc.: C, 68.88; H, 4.87%. MS: m/e 322
[M+]. 1H-NMR (d6-DMSO, d): 10.2 (COOH), 4.0
(OH), 7.6–7.2 (arom. H); 13C{1H}-NMR (d6-DMSO,
l): (C1ꢀC10) 129.5 (15.1), 159.6 (15.2), 115.6 (6.1),
133.2, 120.8, 133.3, 136.5 (11.1), 134.1 (20.2), 129.2
(7.1), 129.5, 167.8 (COOH); 31P{1H}-NMR (d6-DMSO,
l): −14.9.
solution in N,N-dimethylacetamide (10 mmol ml−1
)
were added. The reaction mixture was heated to 130 °C
for 12 h. Thereafter, it was poured onto an ice–water
mixture and extracted with three aliquots of 10 ml of
CH2Cl2. The organic phase was separated, washed with
two portions of 20 ml of water and dried over Na2SO4.
After removal of the solvent in vacuo, 4 was obtained
as a yellow solid. The solid obtained above was treated
with excess HN(SiMe3)2 (2.4 g, 14.9 mmol) and a small
3, Anal. Found: C, 70.91; H, 4.89. C19H15O3P
(322.3). Calc.: C, 70.81; H 4.69%. MS: m/e 322 [M+].
1H-NMR (CD2Cl2, l): 10.6 (COOH), 8.1–7.0 (arom.

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
21
amount of CF3COOH (0.1 g). This mixture was heated
to 150 °C for 10 min. All volatiles were removed in
vacuo. Short path distillation of the residue in vacuo
(200–250 °C, 0.001 mbar) yielded the O-trimethylsi-
lylether 4b of 4 as a colorless off-white solid. Yield: 9.5
5, Anal. Found: C, 79.09; H, 5.92; N, 3.39.
C27H24NOP (409.5). Calc.: C, 79.20; H, 5.91; N, 3.42%.
1H-NMR (CDCl3, l): 1.38 (6.9, CH3), 5.17 (CH), 6.46
(6.9), 6.9–7.7 (arom. H); 13C{1H}-NMR (CDCl3, d):
(C1ꢀC10) 135.0 (19.6), 141.3 (26.0), 128.0 (5.1), 130.0,
128.8, 133.9, 136.7 (10.3), 136.4 (10.2), 133.8 (18.7),
133.6 (20.0), 128.6 (8.2), 128.4 (7.9), 128.7, 167.9 (0.8,
CO), 49.4 (CH), 21.3 (CH3) 142.6 (Ph), 128.4 (Ph),
126.1 (Ph), 127.0 (Ph); 31P{1H}-NMR (CDCl3, l):
−9.4.
1
g (91%). It was identified by H-, 31P{1H}-, 13C{1H}-
and 29Si-NMR spectroscopy. For deprotection, 4b was
dissolved in 30 ml of THF and treated with 4.47 g (30.0
mmol) of NEt4F at ambient temperature for 30 min.
After reducing the volume of the reaction mixture in
vacuo to ca. 10 ml, 100 ml of water was added. The
precipitate formed was extracted with three aliquots of
20 ml of CH2Cl2. The organic extracts were washed
with water and dried over Na2SO4. After evaporation
of the solvent, the remaining residue was dried in vacuo
(50 °C, 0.01 mbar). 4 was obtained as a viscous color-
less oil. Yield: 8.3 g (99%).
1
5a, H-NMR (CDCl3, d): 1.61 (6.9, CH3), 5.29 (CH),
6.21 (6.9, NH), 6.9–7.9 (arom. H); 13C{1H}-NMR
(CDCl3, l): (C1ꢀC10) 92.4, 142.1, 128.3, 127.5, 131.0,
139.7, 142.5, 126.4, 128.6, 128.1, 168.4 (CO), 49.4 (CH),
21.4 (CH3).
7.4. Synthesis of 6
4, Anal. Found: C, 77.74; H, 5.94. C19H17OP (292.3).
1
Calc.: C, 78.07; H, 5.86%. H-NMR (CDCl3, l): 4.86
10.0 g (41.0 mmol) of 2-iodo-isopropylbenzene, 7.63
g (41.0 mmol) of Ph2PH, 4.55 g (45.0 mmol) of NEt3
and 0.47 g (1 mol%) of Pd(Ph3P)4 were dissolved in 60
ml of toluene. The reaction mixture was heated for 24
h at 80 °C, during this time the color of the reaction
mixture changed from yellow to violet. The residue
obtained after evaporation of the solvent was dissolved
in 100 ml of dichloromethane and washed with two
aliquots of a 1 M aqueous KCN solution. The organic
phase was dried over MgSO4 and the solvent was
evaporated. The remaining solid was recrystallized from
an ethanol–water mixture. Yield: 9.95 g (80%).
6, Anal. Found: C, 82.60; H, 6.93. C21H21P (304.4).
Calc.: C, 82.86; H, 6.97%. MS: m/e 304 [M+]. 1H-
NMR (CDCl3, l): 1.9 (6.6, CH3), 3.8 (CH), 6.9–7.4
(arom. H); 13C{1H}-NMR (CDCl3, l): (C1ꢀC10) 134.3
(9.2), 153.4 (23.4), 126.0, 129.3, 125.5 (5.1), 133.4, 137.1
(10.2), 134.0 (19.3), 128.5 (7.1), 128.6, 31.3 (25.4, CH),
23.9 (CH3); 31P{1H}-NMR (CDCl3, l): −13.9.
(1.3, CH2), 2.81 (OH), 6.9–7.8 (arom. H); 13C{1H}-
NMR (CDCl3, l): (C1ꢀC10) 134.6 (14.0), 144.8 (23.0),
127.7 (5.9), 129.1, 127.6 (1.2), 133.2, 135.9 (9.0), 133.8
(19.6), 128.5 (7.1), 128.6, 63.4 (23.1, CH2); 31P{1H}-
NMR (CDCl3, l): −15.0.
1
4b, C22H25OPSi (364.5): H-NMR (CDCl3, l): 0.11
(CH3), 4.93 (CH2), 6.9–7.7 (arom. H); 13C{1H}-NMR
(CDCl3, l): (C1ꢀC10) 133.8, 145.1 (22.2), 126.5 (5.7),
128.9, 127.1 (0.9), 133.0, 136.3 (9.6), 133.8 (19.7), 128.5
1
(7.0), 128.7, 62.8 (26.8, CH2), −0.6 (58.8, J(CꢀSi)
,
SiMe3); 31P{1H}-NMR (CDCl3, l): −15.1; 29Si{1H}-
NMR (CDCl3, l): 19.6.
7.3. Synthesis of 5
2-Iodobenzoyl chloride was prepared by reaction of
12.4 g (50 mmol) of 2-iodobenzoic acid with 60 ml of
SOCl2. It was dissolved in 30 ml of CH2Cl2 and this
solution was treated with 6.1 g (50 mmol) of (R)-(+)-
1-phenylethylamine. Thereafter all volatiles were evapo-
rated in vacuo leaving 5a as a white solid. Yield: 16.2 g
7.5. Synthesis of 7 and 7a
13.2 g (71.0 mmol) of diphenylphosphine and 7.64 g
(78.0 mmol) of KOAc were added to a solution of 23.4
g (71.0 mmol) of 1,4-diodobenzene in 120 ml of
dimethylacetamide. After addition of 7.1 ml of a stock
solution of Pd(OAc)2 (10 mmol ml−1) the reaction
mixture was heated to 70–80 °C. Thereafter 150 ml of
water was added and the solution was extracted with
150 ml of dichloromethane. The organic phase was
dried over MgSO4. All volatiles were removed in vacuo
leaving a colorless solid containing 7 and 7a in about
equal amounts. They were separated by fractional crys-
tallization from ethanol–water. Yields: 12.4 g (45%) 7;
11.8 g (45%) 7a.
(92%). 5a was identified by its H- and 13C{1H}-NMR
1
spectrum; [h]2D0= +29°, c=10, ethanol. A solution of
5.54 g (28.7 mmol) of Ph2PH in 80 ml of N,N-dimethyl-
acetamide was charged with 10.08 g (28.7 mmol) of 5a
and 2.9 ml of Pd(OAc)2 stock solution in N,N-
dimethylacetamide (10 mmol ml−1). After heating the
reaction mixture to 100 °C for 12 h it was poured into
500 ml of water and the solid formed was extracted
with 60 ml of CH2Cl2. For the removal of traces of the
Pd catalyst, the organic phase was extracted with three
aliquots of 5 ml of conc. aqueous solution of KCN.
After washing with water the organic phase was dried
over Na2SO4. The residue remained after removal of
the solvent in vacuo was recrystallized from methanol.
5 was obtained as colorless needles. Yield: 10.5 g (89%).
7, Anal. Calc. for C18H14IP (388.2): C, 55.70; H, 3.64.
Found: C, 56.02; H, 3.69%. MS: m/z (%) 388 [M+].
1H-NMR (C6D6, l): 6.88–7.44 (arom. H); 13C{1H}-

22
D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
NMR (C6D6, l): (C1ꢀC8) 137.7, 135.4 (19.3), 137.6
(7.1), 95.3, 136.9 (11.2), 133.8 (20.4), 128.7 (6.1), 128.9;
31P{1H}-NMR (C6D6, l): −4.8.
(11.1), 133.5 (20.2), 129.1 (7.1), 129.6, 168.6 (1.1,
COOH), 166.7 (COOH); 31P{1H}-NMR (d6-DMSO, d):
−5.6.
7.6. Synthesis of 9
7.8. Synthesis of 13
7.00 g (37.6 mmol) of diphenylphosphine and 12.34 g
(37.6 mmol) of 9a were dissolved in a mixture of 100 ml
of acetonitrile and 10 ml of N,N-dimethylacetamide.
After addition of 12.14 g (120.0 mmol) of triethylamine
and 1.0 g (5.4 mmol) of tributylamine 8.4 mg (37.6
mmol) of palladium(II) acetate was added. Traces of
oxygen dissolved in the solutions were removed by
three freeze–thaw cycles using purified nitrogen as inert
gas. The reaction mixture was heated for 36 h to 95 °C.
Thereafter all volatiles were removed in vacuo (80 °C,
0.1 mbar) and the remaining residue was dissolved in
120 ml of 1 N sodium hydroxide. The solution obtained
was washed with five aliquots of 30 ml of diethylether
and 30 ml of n-hexane. After addition of 10 ml of 2 N
HCl, the solution was heated to 100 °C. On cooling to
ambient temperature, 9 was precipitated from the solu-
tion as white needles which were dried in vacuo
(100 °C, 0.1 mbar). Yield: 11.1 g (76%).
To a solution of 9.26 g (26.9 mmol) of 13a and 14.96
g (80.7 mmol) of nBu3N in 45 ml of N,N-dimethylac-
etamide 5.0 g (26.9 mmol) of Ph2PH and 6.0 mg (27
mmol) of palladium(II) acetate were added. Traces of
oxygen dissolved in the solution were removed by three
freeze–thaw cycles using purified nitrogen as inert gas.
The mixture was heated to 135 °C for 16 h. Thereafter,
all volatiles were removed in vacuo (100 °C, 0.1 mbar).
To the remaining residue 50 ml of a 1.6 N NaOH was
added. The upper organic phase of the two-phase sys-
tem was discarded, the aqueous phase was evaporated
to dryness in vacuo (30 °C, 0.1 mbar). The residue
obtained was extracted with three aliquots of boiling
acetone and two aliquots of 25 ml of ethanol and then
dissolved in 30 ml of water. On acidification of the
aqueous solution, 13 was precipitated as a faint yellow
solid. Yield: 5.88 g (54%).
13, Anal. Found: C, 55.84; H, 4.18. C19H15O6PS·
0.5H2O (411.4). Calc.: C, 55.48; H 3.92%. 1H-NMR
(D2O, l): 7.0–8.0 (arom. H); 13C{1H}-NMR (D2O, l):
(C1ꢀC10) 125.2 (14.2), 163.6 (15.2), 111.5 (3.0), 128.8
(3.0), 135.7, 135.8, 134.0 (6.1), 133.3 (20.2), 128.5 (7.1),
129.2, 171.3 (COOH); 31P{1H}-NMR (D2O, l): −12.3.
9, Anal. Found: C, 58.73; H, 4.22. C19H15O5PS
1
(386.3). Calc.: C, 59.07; H 3.91%. H-NMR (CD2Cl2,
l): 7.1–7.7 (arom. H); 13C{1H}-NMR (d6-DMSO, l):
(C1ꢀC10) 137.7 (15.2), 134.0 (22.2), 131.0 (6.1), 127.2,
148.7 (6.1), 133.6 (20.2), 135.8 (11.2), 133.4 (20.2), 129.0
(7.1), 129.4, 166.6 (COOH); 31P{1H}-NMR (d6-DMSO,
l): −4.8.
7.9. Synthesis of 14
7.7. Synthesis of 10
3.96 g (44.2 mmol) of 2-butylphosphine, 9.01 g (44.2
mmol) of iodobenzene and 5.06 g (50.0 mmol) of
triethylamine were dissolved in 30 ml of dimethylac-
etamide. After addition of 0.414 g of trans-di(m-
acetato)-bis[ortho-(di-2-tolylphosphino)benzyl]dipalla-
dium(II) [38] the reaction mixture was heated for 12 h
to 100 °C. After cooling down to ambient temperature
100 ml of water were added and the reaction mixture
was extracted with 50 ml of n-pentane. The organic
phase was separated and washed with three aliquots of
10 ml of water and dried with Na2SO4. Thereafter, the
solvent was removed in vacuo and the remaining
product was condensed at 60 °C, 0.001 mbar into a
flask chilled with dry ice. Yield: 5.4 g (74%). The
colorless malodorous product was identified by NMR
spectroscopy.
To a solution of 5.78 g (20.0 mmol) of 10a and 3.72
g (20.0 mmol) of Ph2PH in 45 ml of N,N-dimethylac-
etamide 15.76 g (85.0 mmol) of nBu3N and 9.0 mg (40
mmol) of Pd(OAc)2 were added under a blanket of
nitrogen. The reaction mixture was heated to 130–
140 °C for 48 h. Thereafter, the volume of the reaction
mixture was reduced to about 25 ml by evaporation in
vacuo (100 °C, 0.1 mbar). After cooling to room tem-
perature, a solution of 3.20 g (80.0 mmol) of NaOH in
60 ml of water was added, a two-phase system being
formed. The upper phase was discarded, the lower
phase was extracted with three aliquots of 25 ml of
n-hexane. On addition of 120 ml of a 0.6 N HCl, a
precipitate was formed which redissolved on heating
the mixture to 100 °C. Cooling down again to ambient
temperature 10 was precipitated as colorless white
needles. Yield: 6.23 g (79%).
1
14, H-NMR (CDCl3, l): 0.85 (7.4, CH3), 0.86 (7.4,
CH3), 0.95 (14.8, 6.9, CH3), 1.01 (11.4, 7.1, CH3), ca.
1.24 (m, CH2), ca. 1.48 (m, CH2), ca. 1.70 (m, CH), ca.
1.78 (m, CH), 3.94 (205.5, 6.4, PH), 4.10 (205.5, 5.3,
PH), 7.0–7.5 (arom. H); 13C{1H}-NMR (d6-DMSO, l):
(C1, C1%–C8, C8%) 134.3 (13.2), 133.9 (13.2), 134.2
(15.5), 133.8 (15.1), 127.9 (5.4), 127.9 (5.9), 127.9, 127.8,
30.8 (10.0), 30.3 (9.1), 18.8 (5.9), 17.7 (15.5), 28.0 (9.9),
10, Anal. Found: C, 63.49; H 4.24. C21H15O6P
(394.3). Calc.: C, 63.97; H 3.83%. MS: m/e 376 [M+
ꢀH2O]. 1H-NMR (d6-DMSO, l): 13.3 (COOH), 7.2–7.9
(arom. H); 13C{1H}-NMR (d6-DMSO, l): (C1ꢀC8)
139.1 (16.2), 136.7 (19.2), 130.2 (5.1), 136.6, 135.1

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
23
27.6 (15.3), 11.9 (8.1), 11.8 (11.3); 31P{1H}-NMR (d6-
7.13. Synthesis of 16 and 17
DMSO, l): −20.5, −24.8 (1J(PꢀH)=205.5).
5.51 g (50.0 mmol) of phenylphosphine, 13.1 g (50.0
mmol) of 3-iodo-4-methylbenzoic acid and 10.12 g
(100.0 mmol) of NEt3 were dissolved in 170 ml of
acetonitrile. After addition of a solution of 51.8 mg (50
mmol) of tris(dibenzylideneacetone) dipalladium chloro-
form adduct and 41.3 mg (100 mmol) of 1,3-
bis(phenylphosphino)propane in 15 ml of acetonitrile
the solution was heated to 90 °C for 48 h. Thereafter,
all volatiles were removed in vacuo (30 °C, 1 mbar).
The residue was dissolved in 200 ml of 0.5 N NaOH.
After extraction with diethylether (160 ml) and n-hex-
ane (50 ml), the solution was acidified with HCl until a
pH value of ca. 2 was reached. The precipitate formed
was separated by filtration, washed with 150 ml of
water and dried in vacuo. For further purification,
colorless 16 was recrystallized from CH2Cl2. Yield: 9.4
g (77%).
16, Anal. Found: C, 68.45; H, 5.48. C14H13O2P
(244.2). Calc.: C, 68.85; H, 5.36%. MS: m/e 244 [M+].
1H-NMR (CDCl3, l): 2.5 (CH3), 5.3 (223, PH), 7.1–8.0
(arom. H); 13C{1H}-NMR (CDCl3, l): (C1ꢀC10) 136.4
(8.1), 147.9 (17.1), 130.3 (3.0), 130.6, 127.2 (3.0), 132.5
(10.1), 135.1 (12.1), 134.3 (17.2), 128.6 (7.1), 128.9,
172.0 (CO), 21.8 (14.2, CH3); 31P{1H}-NMR (CDCl3,
l): −46.5 (223.0).
7.10. Synthesis of 15a
0.31 g (5.0 mmol) of boric acid dissolved in 5 ml of
water were added to a solution of 3.22 g (10.0 mmol) of
3 in 20 ml of ethanol. After addition of 2.10 g (15.0
mmol) of a 35% aqueous solution of NEt4OH the
reaction mixture was heated to 80 °C for 1 h. The
residue obtained after removal of all volatiles in vacuo
(30 °C, 1 mbar) was recrystallized from a 2-propanol–
N,N-dimethylacetamide 50:20-mixture. Yield: 2.56 g
(66%).
15a, Anal. Found: C, 70.21; H, 6.32; N, 1.77.
C46H46BNO6P2 (781.6). Calc.: C, 70.69; H, 5.93; N
1.79%. 1H-NMR (CDCl3, l): 3.1 (CH2), 1.11 (7.2,
CH3), 6.8–8.2 (arom. H); 13C{1H}-NMR (CDCl3, l):
(C1ꢀC10) 125.5 (9.1), 135.0 (22.2), 118.9 (8.1), 159.8,
115.5 (8.1), 139.8 (21.2), 137.59 (12.1), 137.61 (12.1),
133.18 (19.2), 133.22 (19.2), 128.39 (7.1), 128.41 (7.1)
128.49, 128.51, 163.0 (CO), 52.2 (CH2), 7.1 (CH3);
31P{1H}-NMR (CDCl3, l): −6.5.
7.11. Synthesis of 15b
0.39 g (0.5 mmol) of 15a dissolved in 10 ml of
CH2Cl2 were added to a solution of 0.23 g (0.5 mmol)
of [Rh(norbornadiene)Cl]2 in 10 ml of CH2Cl2. The
reaction mixture was stirred at ambient temperature for
2 days. After evaporation of the solvent in vacuo
(20 °C, 0.1 mbar) 15b was left as brown solid. Yield:
0.62 g (100%).
15b, Anal.. Found: C, 57.49; H, 5.24.
C60H62BCl2NO6P2Rh2 (1242.6). Calc.: C, 57.99, H,
5.03%. 1H-NMR (CDCl3, l): 7.6–7.2 (arom. H);
31P{1H}-NMR (CDCl3, l):=32.0 (J(RhꢀP)=171.1 Hz).
The tertiary phosphine 17 was obtained in a proce-
dure analogous to that above using 2.44 g (10.0 mmol)
of 16, 2.48 g (10.0 mmol) of 3-iodobenzoic acid, 4.05 g
(40 mmol) of NEt3 and 30 ml of acetonitrile. The
catalyst used was of palladium(II)acetate (2.2 mg, 10
mmol). 17 was obtained using the same work up proce-
dure as above as an off-white powder. Yield: 2.93 g
(81%).
17, Anal. Found: C, 68.97; H, 4.91. C21H17O4P
(364.3). Calc.: C, 69.23; H, 4.70%. MS: m/e 264 [M+].
1H-NMR (d6-DMSO, l): 1.5 (CH3), 6.3–7.3 (arom. H);
13C{1H}-NMR (d6-DMSO, l): (C1ꢀC10) 135.8 (13.1),
147.1 (25.3), 128.3, 133.5, 128.1, 128.8, 134.4 (9.1),
133.5 (20.2), 129.8 (8.1), 129.8; C6H4ꢀ3-COOH: 136.1
(11.2), 134.7 (24.3), 130.8 (8.1), 128.3, 128.2, 137.4
(16.2), 166.3 (COOH), 166.2 (COOH), 20.6 (20.2, CH3);
31P{1H}-NMR (d6-DMSO; l): −12.9.
7.12. Synthesis of 15c
To a solution of 3.22 g (10.0 mmol) of 3 in 40 ml of
CH2Cl2 1.22 g (10.0 mmol) of benzeneboronic acid,
dissolved in 60 ml of CH2Cl2, was added. The solution
was heated to reflux for 0.5 h. After removal of the
solvent in vacuo (30 °C, 1 mbar) 15c was obtained as a
colorless solid. Yield: 4.0 g (99%).
7.14. Synthesis of 18
2.27
g
(8.72 mmol) of bis-1,3-phenylphos-
15c, Anal. Found: C, 73.04; 4.63. C25H18BO3P
(408.2). Calc.: C, 73.56; H, 4.44%. MS: m/e 408, 407
phinopropane and 1.96 g (20.0 mmol) of KOAc were
dissolved in 50 ml of N,N-dimethylacetamide. After
addition of 0.9 ml of Pd(OAc)2 solution in N,N-
dimethylacetamide (10 mmol ml−1) the mixture was
heated to 130 °C for 48 h. The reaction mixture was
poured into 300 ml of water and the precipitate formed
was extracted with three aliquots of 20 ml of CH2Cl2.
1
(11B, 10B) [M+]. H-NMR (CD2Cl2, l): 6.0–7.2 (arom.
H); 13C{1H}-NMR (d6-DMSO, l): (C1ꢀC10) 118.2
(10.1), 128.1 (26.3), 104.6 (9.1), 154.3, 109.2 (7.1), 132.2
(18.2), 128.9 (10.1), 124.7 (22.2), 119.9 (7.1), 120.1,
124.9 (Ph), 118.9 (Ph), 121.2 (Ph), 163.4 (CO); 31P{1H}-
NMR (d6-DMSO, l):−6.4.

24
D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
0.01 g (0.6 mol%) of palladium(II) acetate the mixtures
were stirred at 80 °C for 3 days. Thereafter, all volatiles
were removed in vacuo. Water (100 ml) and CH2Cl2
(100 ml) were added to the remaining residue. The
organic phase was separated and washed with 50 ml of
water and three aliquots of a 1 M aqueous solution of
KCN. After drying the organic phase with MgSO4, the
solvent was evaporated. 20a and 20b were obtained as
oily residues. 20b could be recrysallized from ethanol–
water. Yield: 1.78 g (63%) 20b.
20a, Anal. Found: C, 84.85; H 6.11. C25H21P (352.4).
Calc.: C, 85.21; H, 6.00%. MS: m/e 352 [M+]. 1H-
NMR (CDCl3, l): 2.2 (CH3), 6.9–7.5 (arom. H);
13C{1H}-NMR (CDCl3, l): (C1ꢀC10) 137.2 (11.2),
147.6 (30.5), 130.3 (3.1), 128.7, 129.7 (5.1), 133.8 (20.3),
136.7 (11.2), 136.9 (10.2), 133.9 (19.3), 133.8 (20.3),
128.4 (5.1), 128.3, 128.2, 141.0 (o-tolyl), 135.7 (o-tolyl),
129.6 (o-tolyl), 127.5 (o-tolyl), 124.8 (o-tolyl), 127.3
(o-tolyl), 20.4 (4.1, CH3); 31P{1H}-NMR (CDCl3, l):
−11.7.
The organic phase was washed with 30 ml of water and
dried over Na2SO4. The residue obtained after removal
of the solvent was suspended in 10 ml of methanol, and
dilute HCl (10%) was added until a pH value of ca. 4
was reached. After filtration the solid material was
recrystallized from methanol. Thereby an enrichment of
one diastereoisomer (I) in a 8:3 ratio was achieved
(l= −34.15 (I), −34.28 (II)). Yield: 2.5 g (65%).
18, Anal. Found: C, 73.40; H, 6.51; N, 6.49.
C27H28N2P2 (442.5). Calc.: C, 73.29; H, 6.39; N, 6.33%.
1H-NMR (CDCl3, l): 1.7, 2.2 (C3H6), 3.6 (NH2), 6.6–
7.4 (arom. H); 13C{1H}-NMR (CDCl3, l): (C1ꢀC10)
119.42 (9.9), 119.44 (10.1), 150.2 (18.9), 115.3 (2.7),
130.2, 118.6 (2.5), 132.6 (3.7), 137.9 (10.2), 131.9 (17.6),
128.4 (6.5), 128.2, 28.0 (23.6, CH2), 22.39 (17.3, CH2),
22.35 (17.4, CH2); 31P{1H}-NMR (CDCl3, l): −34.3,
−34.2.
7.15. Synthesis of 19a and 19b
To a solution of 24.73 g (87.4 mmol) or 25.0 g (88.0
mmol) of 2-bromoiodobenzene and 16.27 g (87.4 mmol)
of Ph2PH or 4.85 g (44.0 mmol) of PhPH2 in 200 ml of
toluene 9.8 g (97.0 mmol) or 17.8 g (194.0 mmol) of
triethylamine was added. After addition of 0.50 g (0.4
mmol) or 1.05 g (0.9 mmol) of Pd(PPh3)4, respectively,
the mixtures were stirred at 80 °C for 12 h. The solvent
was removed in vacuo (50 °C, 0.1 mbar) and the
remaining residue was dissolved in 150 ml of CH2Cl2.
The solution was washed with two aliquots of 150 ml of
water and dried over MgSO4. The residues left after
evaporation of CH2Cl2 were purified by short path
distillation at 200–300 °C. 19a was obtained as a col-
orless solid. For a further purification 19b was recrys-
tallized from ethanol/water. Yield: 28.0 g (94%) 19a,
15.7 g (85%) 19b.
20b, Anal. Found: C, 84.02; H 5.89. C25H21P (352.4).
Calc.: C, 85.21; H, 6.00%. MS: m/e 352 [M+].1H-NMR
(CDCl3, l): 2.5 (CH3), 6.9–7.5 (arom. H); 13C{1H}-
NMR (CDCl3, l): (C1ꢀC10) 135.7 (14.3), 148.3 (29.5),
129.5, 130.1, 129.5, 134.2, 137.8 (11.2), 133.8 (20.3),
128.3 (6.1), 128.6, 138.8 (6.1, p-tolyl), 127.1 (p-tolyl),
130.1 (p-tolyl), 136.7 (p-tolyl), 21.1 (CH3); 31P{1H}-
NMR (CDCl3, l): −12.3. 20b could not be obtained in
a satisfying analytical purity.
7.17. Synthesis of 21a and 21b
These compounds have been obtained in an
analogous way as 20a and 20b. Thus 4.20 g (10.0 mmol)
of 19b, 5.67 g (41.0 mmol) of potassium carbonate, 0.02
g (1.2 mol%) of palladium(II) acetate and 3.13 g (23.0
mmol) of 2- or 4-tolueneboronic acid, respectively, in
100 ml of toluene gave 21a and 21b after recrystalliza-
tion from ethanol–water. Yield: 0.95 g (22%) 21a or
2.28 g (52%) 21b.
1
19a, C18H14BrP (341.2). H-NMR (CDCl3, l): 6.8–
7.6 (arom. H); 13C{1H}-NMR (CDCl3, l): (C1ꢀC10)
138.9 (12.2), 129.9 (30.5), 132.9 (2.0), 130.0, 127.3,
134.3, 135.8 (11.2), 133.9 (19.3), 128.5 (7.1), 128.9;
31P{1H}-NMR (CDCl3, l): −3.5.
21a, Anal. Found: C, 86.78; H, 6.24. C32H27P (442.5).
Calc.: C, 86.85; H, 6.15%. MS: m/e 442 [M+]. 1H-
NMR (CDCl3, l): 1.6 (CH3), 1.8 (CH3), 2.0 (CH3), 2.2
(CH3), 6.4–7.5; 13C{1H}-NMR (CDCl3, l): 20.5 (5.1,
CH3), 20.1 (4.1, CH3), 19.8 (3.0, CH3), 19.6 (5.1, CH3);
31P{1H}-NMR (CDCl3, l):−17.1, −20.1, −20.2.
21b, Anal. Found: C, 86.50; H, 6.12. C32H27P (442.5).
Calc.: C, 86.85; H, 6.15%. MS: m/e 442 [M+]. 1H-
NMR (CDCl3, l): 2.4 (CH3), 6.9–7.5 (arom. H);
13C{1H}-NMR (CDCl3, l): (C1ꢀC10) 136.4 (14.3),
148.0 (29.5), 129.9 (4.1), 128.1, 129.4 (3.1), 134.3, 137.6
(13.2), 134.0 (19.3), 128.2 (6.1), 128.2, 138.7 (6.1, p-
tolyl), 127.0 (p-tolyl), 128.4 (p-tolyl), 136.3 (p-tolyl),
21.1 (CH3); 31P{1H}-NMR (CDCl3, l): −18.8.
19b, Anal. Found: C, 51.61; H, 3.19. C18H13Br2P
(420.1). Calc.: C, 51.46; H, 3.12%. MS: m/e 422 (81Br,
1
81Br), 420 (79Br, 81Br), 418 (79Br, 79Br) [M+]. H-NMR
(CDCl3, l): 6.8–7.7 (arom. H); 13C{1H}-NMR (CDCl3,
l): (C1ꢀC10) 137.8 (11.2), 129.9 (33.6), 132.9 (2.0),
130.3, 127.4, 134.4, 134.5, 134.2 (21.4), 128.7 (7.1),
129.3; 31P{1H}-NMR (CDCl3, l): −2.7.
7.16. Synthesis of 20a and 20b
A suspension of 2.73 g (8.0 mmol) of 19a and 2.21 g
(16.0 mmol) of potassium carbonate in 100 ml of
toluene was charged with 1.20 g (8.8 mmol) of 2- or
4-tolueneboronic acid, respectively. After addition of

D.J. Brauer et al. / Journal of Organometallic Chemistry 645 (2002) 14–26
25
7.18. X-ray structural analyses of 3 and 6
direct methods and was refined with a SHELXTL pro-
gram package (version 5.03) with non-hydrogens an-
isotropic and hydrogens isotropic. Crystal data and
refinement details are given in Table 2.
7.18.1. Crystal structure analysis of
Ph2PꢀC6H3ꢀ3-COOHꢀ4-OH (3)
A crystal of 3 was mounted in a glass capillary. X-ray
data were collected using a Siemens P4/V diffractome-
ter equipped with a graphite monochromator and em-
ploying Mo–Ka radiation. The structure was solved
using direct methods and was refined by full matrix
least squares. Crystal data and refinement details are
given in Table 2. The program SHELXTL was used for
the refinement.
8. Supplementary material
Further details of the crystal structure investigations
on 3 and 6 are available from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2,
IET, UK (Fax: +44-1223-336033; e-mail: de-
posit@ccdc.cam.ac.uk) on quoting the depository num-
ber CCDC 147286 and CCDC 147048 for 3 and 6,
respectively.
7.19. Crystal structure analysis of Ph2PꢀC6H4ꢀ2-i-Pr
(6)
A crystal of 6 was glued to a glass fiber. X-ray data
were measured with a Siemens P3 diffractometer
equipped with a graphite monochromator and employ-
ing Mo–Ka radiation. The structure was solved by
Acknowledgements
This work was supported by the Bundesministerium
fu¨r Bildung, Wissenschaft, Forschung und Technologie
and the Fonds der Chemischen Industrie. Celanese
Chemicals Europe GmbH, Clariant GmbH and Aventis
Research and Technologies are thanked for financial
support.
Table 2
Crystal and refinement data for 3 and 6
3
6
Chemical formula
Formula weight
Temperature (K)
Crystal system
Space group
C19H15O3P
322.3
293(2)
C21H21
304.4
293(2)
Orthorhombic
Pbca
6.538(7)
12.519(5)
16.860(7)
90
90
90
P
Triclinic
References
(
P1
,
a (A)
5.716(1)
11.054(2)
13.397(3)
95.91(3)
96.31(3)
92.91(3)
835.2(3)
2
,
b (A)
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,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
3490.6(8)
8
1.158
Z
Dcalc (mg m−3
)
1.282
Absorption coefficient
(mm−1
F(000)
Crystal size (mm)
q-range (°)
0.176
0.152
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336
1296
0.58×0.46×0.32 0.20×0.24×0.32
2.28–24.99
05h56,
−135k513,
−155l515
3252
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−165l50
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1634
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Absorption correction
Max/min transmission
Parameters
826
Semiempirical
0.733–0.592
216
None
–
204
R1=0.0322,
wR2=0.0400
R1=0.0916,
wR2=0.0465
0.14/−0.14
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wR2=0.1064
0.200/−0.188
Largest difference peak
−3
,
and hole (e A
)

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