Synthesis, Coordination, and Catalytic Use of 1′-(Diphenylphosphino)ferrocene-1-sulfonate Anion

Article abstract of DOI:10.1021/acs.organomet.8b00178

Sulfonation of (diphenylphosphinothioyl)ferrocene (1) with chlorosulfonic acid in acetic anhydride affords the crude sulfonic acid Ph₂P(S)fcSO₃H (2; fc = ferrocene-1,1′-diyl), which can be efficiently purified and isolated after conversion to Ph₂P(S)fcSO₃(HNEt₃) (3). Methyl triflate/P(NMe₂)₃ can be used to convert compound 3 to the stable sulfonate salt Ph₂PfcSO₃(HNEt₃) (4) and Ph₂P(Me)fcSO₃ (5) as a minor, zwitterionic byproduct. Alternatively, compound 4 can be prepared by lithiation of 1′-(diphenylphosphino)-1-bromoferrocene (6; Ph₂PfcBr) and trapping of the lithiated intermediate with SO₃·NMe₃. Reactions of [(L^NC)PdX]₂ and [(L^SC)PdX]₂, where X = Cl, AcO, L^NC = 2-[(dimethylamino-κN)methyl]phenyl-κC¹, and L^SC = 2-[(methylthio-κS)methyl]phenyl-κC¹, with 4 uniformly produced the bis-chelate complexes [(L^NC)Pd(Ph₂PfcSO₃-κ²O,P)] (7) and [(L^SC)Pd(Ph₂PfcSO₃-κ²O,P)] (8), respectively. The reaction of [PdCl₂(MeCN)₂] with 4 afforded the bis(phosphine) complex trans-(Et₃NH)₂[PdCl₂(Ph₂PfcSO₃-κP)₂] (9). Complexes 7-9 were used as defined catalyst precursors for the Suzuki-Miyaura cross-coupling of boronic acids with acyl chlorides to give ketones. Reactions of aromatic substrates in the presence of Na₃PO₄ and 9, the base and Pd source that showed the best performance, in a toluene/water biphasic system provided the coupling products in good yields; however, aliphatic substrates typically resulted in poor conversions. Extensive tests of the reaction scope revealed that the transposition of the substituents between the reaction partners can have a substantial effect on the yield of the coupling product in otherwise complementary reactions, which highlights the importance of the judicious choice of starting materials for this particular reaction.

Full text of DOI:10.1021/acs.organomet.8b00178

Article
Cite This: Organometallics XXXX, XXX, XXX−XXX
Synthesis, Coordination, and Catalytic Use of 1′-
(
Diphenylphosphino)ferrocene-1-sulfonate Anion
̌
́
́ ̌ ́ ̌ ̌
Martin Zabransky, Ivana Císarova, and Petr Stepnicka*
Department of Inorganic Chemistry, Faculty of Science, Charles University, Hlavova 2030, 128 40 Prague, Czech Republic
*
S Supporting Information
ABSTRACT: Sulfonation of (diphenylphosphinothioyl)-
ferrocene (1) with chlorosulfonic acid in acetic anhydride
affords the crude sulfonic acid Ph P(S)fcSO H (2; fc =
2
3
ferrocene-1,1′-diyl), which can be efficiently purified and
isolated after conversion to Ph P(S)fcSO (HNEt ) (3).
2
3
3
Methyl triflate/P(NMe ) can be used to convert compound
2
3
3
to the stable sulfonate salt Ph PfcSO (HNEt ) (4) and
2
2 3 3
Ph P(Me)fcSO3 (5) as a minor, zwitterionic byproduct.
Alternatively, compound 4 can be prepared by lithiation of
1
′-(diphenylphosphino)-1-bromoferrocene (6; Ph PfcBr) and trapping of the lithiated intermediate with SO ·NMe . Reactions
2
3
3
NC SC NC 1 SC
of [(L )PdX] and [(L )PdX] , where X = Cl, AcO, L = 2-[(dimethylamino-κN)methyl]phenyl-κC , and L = 2-
2
2
1
NC
2
[
(methylthio-κS)methyl]phenyl-κC , with 4 uniformly produced the bis-chelate complexes [(L )Pd(Ph PfcSO -κ O,P)] (7)
2 3
SC
2
and [(L )Pd(Ph PfcSO -κ O,P)] (8), respectively. The reaction of [PdCl (MeCN) ] with 4 afforded the bis(phosphine)
2
3
2
2
complex trans-(Et NH) [PdCl (Ph PfcSO -κP) ] (9). Complexes 7−9 were used as defined catalyst precursors for the Suzuki−
3
2
2
2
3
2
Miyaura cross-coupling of boronic acids with acyl chlorides to give ketones. Reactions of aromatic substrates in the presence of
Na PO and 9, the base and Pd source that showed the best performance, in a toluene/water biphasic system provided the
3
4
coupling products in good yields; however, aliphatic substrates typically resulted in poor conversions. Extensive tests of the
reaction scope revealed that the transposition of the substituents between the reaction partners can have a substantial effect on
the yield of the coupling product in otherwise complementary reactions, which highlights the importance of the judicious choice
of starting materials for this particular reaction.
INTRODUCTION
Chart 1. Relevant Examples of Phosphinosulfonate Ligands
■
Sulfonated phosphines, such as the iconic 3,3′,3″-
phosphinidynetris(benzenesulfonic acid) trisodium salt
1
(
TPPTS), are recognized as efficient supporting ligands for a
range of transition-metal-catalyzed reactions and, specifically,
2
for reactions conducted in aqueous reaction media. However,
their advantages have not been adequately reflected in the3
chemistry of otherwise widely utilized ferrocene phosphines.
Although the synthesis of ferrocenesulfonic acid, FcSO H (Fc =
3
ferrocenyl) by the direct sulfonation of ferrocene was described
4
,5
already in 1955, the chemistry of sulfonated phosphinoferro-
cene ligands remained unexplored for decades, likely due to
synthetic complications resulting from the facile oxidation of
6
,7
the ferrocene unit during the sulfonation.
To avoid the synthetic challenges associated with the use of
aggressive sulfonating agents, we initially prepared phosphino-
ferrocene sulfonates indirectly by the assembly of suitable
viously for the synthesis of 2-phosphinobenzenesulfonates IV
13,14
from the corresponding sulfonic acids.
Similar to the
studies conducted on IV-type ligands, Pd(II) and Ni(II)
8
complexes with these ferrocene ligands were employed as
functional building blocks. The resulting compounds Ia-d and
1
1,15
9
catalysts for various (co)polymerization reactions.
II (Chart 1), in which the phosphinoferrocene and sulfonate
16
10
Given our longstanding interest in the chemistry of
functional, hybrid phosphinoferrocene donors formally
resulting through the replacement of one phosphine substituent
moieties are connected by an amide linkage, not only were
1
7
8
,9
highly hydrophilic but also showed favorable catalytic activity.
In contrast, Erker et al. synthesized a series of 2-
11,12
phosphinoferrocene-1-sulfonic acids III,
which are indeed
closer to the archetypal phosphinosulfonate donors, by utilizing
an ortho-lithiation/functionalization approach developed pre-
Received: March 26, 2018
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00178
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Organometallics
Article
1
8
in 1,1′-bis(diphenylphosphino)ferrocene (dppf) with another
functional group, we decided to synthesize 1′-
Subsequent deprotection of the phosphine group was
performed by reacting salt 3 successively with methyl triflate
and tris(dimethylamino)phosphine. Unlike treatment of 3 with
(
diphenylphosphino)ferrocene-1-sulfonic acid (V), which
22
represents a hitherto unknown isomer of compound III (R =
Ph) and could complement the analogous, previously studied
phosphinocarboxylic ligand 1′-(diphenylphosphino)ferrocene-
only P(NMe ) , this deprotection, consisting of sequential S-
2 3
23
methylation and desulfurization, could advantageously be
performed at relatively lower temperatures, which prevents
thermal decomposition, and also in a more polar, halogenated
solvent that can better dissolve the sulfonate salt. However, the
use of MeOTf somewhat complicated the subsequent
19
1-carboxylic acid (Hdpf).
This contribution describes the synthesis of triethylammo-
nium 1′-(diphenylphosphino)ferrocene-1-sulfonate, a stable salt
24
of the target acid V, the coordination of the 1′-
purification due to partial alkylation of the regenerated
phosphine moiety upon the formation of the zwitterionic side
product Ph P(Me)fcSO (5) and, more importantly, due to the
(
diphenylphosphino)ferrocene-1-sulfonate anion toward Pd(II)
ions bearing different supporting ligands, and the activity of the
prepared complexes in Pd-catalyzed Suzuki−Miyaura-type
cross-coupling of acyl chlorides with boronic acids to give
ketones.
2
3
+
formation of other counterions (such as (Me N) PSMe and
2
3
+
25
+
Et NMe ) that had to be replaced with HNEt3 to ensure
3
sample homogeneity.
Under the optimized conditions, the crude product obtained
after sequential treatment of 3 with MeOTf and P(NMe2)3
26
RESULTS AND DISCUSSION
■
Synthesis of the Target Phosphinoferrocene Sulfo-
nate. Two synthetic routes were designed for the preparation
of 1′-(diphenylphosphino)ferrocene-1-sulfonic acid. In the first
route (Scheme 1), 1′-(diphenylphosphinothioyl)ferrocene,
was passed through a cation exchanger (to produce free acid
27
V ). The obtained crude material was purified by chromatog-
raphy over silica gel using a NEt -containing mobile phase. This
3
procedure was repeated twice, and ultimately, salt 4 was
crystallized from dichloromethane/ethyl acetate to produce
analytically pure product in 39% yield. Compound 4 thus
isolated is an air-stable, rusty orange crystalline solid that is
soluble in water, methanol, dichloromethane, and chloroform
but is practically insoluble in diethyl ether and hexane. In
addition, the combined fractions predominantly containing
zwitterion 5 were rechromatographed and crystallized to
provide 5 in 8% yield.
Scheme 1. Synthesis of 4 by Sulfonation of 1
The alternative synthesis of 4 was based on a lithiation/
functionalization approach commonly used to prepare function-
28
alized ferrocene phosphines (Scheme 2). In the first step, 1′-
Scheme 2. Preparation of 4 by Lithiation/Functionalization
of 6
FcP(S)Ph (1; Fc = ferrocenyl), serving as a P-protected
2
starting material, was sulfonated with chlorosulfonic acid in
acetic anhydride as previously described for the sulfonation of
2
0
ferrocene itself. Following hydrolysis and concentration, the
formed 1′-(diphenylphosphinothioyl)ferrocene-1-sulfonic acid
21
(
2) was isolated by chromatography. Screening experiments
showed that the outcome of the reaction is strongly dependent
on the reaction time and that free acid 2 is relatively unstable.
For instance, when the sulfonation was performed at room
temperature overnight, the yield of 2 was only 19% with the
corresponding phosphine oxide being formed as a side product
(diphenylphosphino)-1-bromoferrocene (6) was lithiated with
butyllithium in THF at −78 °C, and the formed lithium salt
29
(
approximately 16%). When the reaction time was decreased to
h, the yield of 2 increased to 68%, whereas reaction times of 1
h and 30 min resulted in 77% and 64% isolated yields of crude
, respectively. Notably, attempts to sulfonate FcPPh and
was (without isolation) reacted with SO ·NMe . Chromato-
3 3
3
graphic purification afforded (diphenylphosphino)ferrocene, a
major side product resulting from protonolysis of the lithiated
30
2
intermediate (33% yield), and crude salt Ph PfcSO Li, which
2
2 3
FcPPh ·BH by a similar procedure were unsuccessful and
was directly converted to the free acid over a cation exchanger
2
3
resulted in the formation of phosphine oxide FcP(O)Ph (see
and neutralized with NEt . Subsequent chromatographic
2
3
ref 6).
purification followed by crystallization produced salt 4 in 30%
yield. Compound 5, which was detected in only minor amounts
in this case, was not isolated.
As free acid 2 proved to be prone to decomposition
(
especially in solution), in subsequent experiments, it was
converted to the corresponding triethylammonium salt 3. This
salt is stable enough to be purified by chromatography and can
even be crystallized. The optimized procedure described below
Both synthetic routes provide the target salt 4 in similar
overall yields (approximately 30%). However, the lithiation
route is shorter and operationally simpler (especially during the
isolation of the product), whereas the sulfonation route uses an
easily accessible starting material but requires a more tedious
(see the Experimental Section) reproducibly afforded salt 3 in
yields of approximately 75%.
B
DOI: 10.1021/acs.organomet.8b00178
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Organometallics
Article
a
isolation procedure. It is also worth mentioning that, although
the sulfonation route does not involve any alkylation step, it
still produces zwitterion 5 as a side product (albeit in tiny
amounts). Additional experiments revealed that compound 5 is
indeed formed during chromatography over a cation exchanger,
presumably by acid-catalyzed alkylation of 4 (or free acid V)
Table 1. Selected Distances (Å) and Angles (deg) for 3−5
param
3
4
5
Y
S1P
void
C23
C1−S1
S−O1
S−O2
S−O3
C6−P
P−Y
1.760(2)
1.470(1)
1.436(2)
1.452(2)
1.787(2)
1.9614(7)
1.3(1)
1.755(2)
1.466(2)
1.445(2)
1.442(2)
1.812(2)
n.a.
1.775(2)
1.461(2)
1.450(2)
1.454(2)
1.756(2)
1.790(2)
1.8(1)
3
1
with methanol.
1
13
The H and C NMR spectra of 3−5 showed signals typical
for a disubstituted ferrocene unit, an attached PPh moiety, and
2
HNEt cation (if present). The signals of the P-Me group in 5
3
3
1
2
∠Cp1,Cp2
τ
2.2(1)
appear as P-coupled doublets at δ 3.08 ( J = 14.5 Hz) and
δ 6.67 ( J = 59 Hz). The derivatization of the phosphorus
substituent is clearly reflected in the P NMR spectra, which
H
PH
1
32
157.4(1)
86.3(1)
87.8(1)
C
PC
a
3
1
Definitions: Cp1 and Cp2 are the C(1−5) and C(6−10) cyclo-
pentadienyl rings, respectively. Cg1 and Cg2 are their respective
centroids. τ is the torsion angle of C1−Cg1−Cg2−C6. n.a. = not
applicable.
show distinct singlets at δ 42.0, −16.5 and 24.5 for 3−5,
P
1
3
respectively. In addition to the downfield shift of the C NMR
signal of the ferrocene C-SO carbon (δ ∼94 for 3 and 4, δ
99 for 5), the presence of the sulfonate moiety was further
3
C
C
∼
confirmed by IR spectra showing bands due to the ν (SO )
as
3
−1
upon introduction of the electronegative sulfur atom or
quaternization. Additionally, the presence of the fourth
substituent on the phosphorus atom in 3 and 5 increases the
C−P−C(Ph) angles. In contrast, the geometry of the sulfonate
moiety is similar in all three compounds and is comparable to
that determined for (NH ) [fc(SO ) ] and the salts obtained
from FcSO H and various nitrogen bases. In the structures of
and ν (SO ) vibrations (ν ∼1150−1250 cm , ν ∼1040
s
3
as
s
−
1
8
cm ).
The crystal structures of compounds 4 and 5 are displayed in
Figure 1 (a structural diagram for compound 3 is available in
the Supporting Information). Selected geometric parameters
are presented in Table 1.
34
4 2
3 2
35
3
3
and 4, the sulfonate groups become involved in charge+-
assisted hydrogen bonding interactions with the HNEt3
cations (N1−H1N···O1−S) at identical N1···O1 distances
(
2.758(2) and 2.759(2) Å, respectively).
Preparation of the Pd(II) Complexes. The coordination
properties of the phosphinoferrocene sulfonate anion
−
Ph PfcSO3 were assessed through reactions of the salt 4
2
with Pd(II) precursors possessing different supporting ligands.
The aim was to prepare a series of compounds in which the
anion coordinates in diverse modes, particularly as a P,O-
chelating and a P-monodentate ligand. First, we studied the
YC
reactions of 4 with acetate-bridged dimers [(L )Pd(OAc)]
2
YC
YC
containing ortho-palladated auxiliary ligands L (L = 2-
1
[
(dimethylamino-κN)methyl]phenyl-κC and 2-[(methylthio-
κS)methyl]phenyl-κC ). These reactions proceeded with
1
cleavage of the dimeric Pd(II) precursors and elimination of
(
7
Et NH)OAc to produce the structurally analogous complexes
and 8, which feature the phosphinoferrocene sulfonate anion
3
as an O,P-chelating donor (Scheme 3).
Scheme 3. Synthesis of Pd(II) Complexes with Ortho-
Palladated Auxiliary Ligands
Figure 1. Molecular structures of compounds 4 and 5. The NH···O
hydrogen bond is indicated by a dotted line.
The central ferrocene moieties in the structures of 3−5 show
1
8a
almost negligible tilting but different conformations. In the
case of 4 and 5, the phosphorus and sulfonate substituents
assume positions halfway between synclinal eclipsed and
anticlinal staggered conformations, whereas in 3, the sub-
stituents are rotated to more distant positions (cf. the τ angles
in Table 1). The P−C distances vary noticeably across the
33
series, increasing from 5 via 3 to 4. This increase can be
attributed to the increasing P−C bond orders resulting from
the shift of the electron density toward the phosphorus atom
C
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Article
Identical products were isolated from the reactions of 4 with
YC
[
(L )PdCl] (after crystallization). Indeed, NMR monitoring
2
NC
of the reaction between 4 and [(L )PdCl] (in CDCl )
indicated the formation of two compounds with P NMR
2
3
3
1
signals at δ 28.4 and 32.8, which correspond to 7 and the
P
NC
plausible bridge cleavage product (Et NH)[(L )PdCl-
Ph PfcSO -κP)] (see Scheme 3), respectively. However,
3
3
6
(
2 3
the latter complex, which is the major component in this
mixture, is converted to chelate complex 7 during crystallization
through the elimination of (Et NH)Cl.
3
The signals of the coordinated NMe and SMe fragments in
2
1
13
the H and C NMR spectra of 7 and 8 appear as characteristic
P-coupled doublets that suggest a trans-P,Y arrangement,
3
1
while the coordination of the phosphine moiety is indicated by
31
the shift of the P NMR signals to a lower field (δ 28.4 and
P
26.2 for 7 and 8, respectively). The formulation of 7 and 8 was
further supported by the ESI MS spectra showing the respective
pseudomolecular ions.
Compound 7 crystallized as an ethyl acetate solvate with the
solvent molecules disordered in the structural voids and with
two structurally independent but similar molecules per the
asymmetric unit (the molecules differ mainly in the
conformation of the peripheral substituents; see the overlap
in the Supporting Information). Views of molecule 1 of this
37
complex and the structure of compound 8 are shown in
Figure 2. Selected geometric parameters are given in Table 2.
The molecules of both complexes include two metallocycles
sharing the central Pd atom and have the anticipated trans-P,Y
geometry. The Pd−donor distances fall into the ranges
YC
II
reported for analogous (L )Pd complexes with phosphino-
16h,i
ferrocene carboxylate ligands,
and the coordination environ-
ments of the Pd(II) ions are characteristically angularly
distorted. In both structures, the most acute cis-interligand
angle is associated with the small and rigid ring constituted by
YC
YC
Figure 2. Molecular structures of (L )Pd(II) complexes 7 (molecule
) and 8.
the chelating L ligand, whereas the largest interligand angle is
1
the P−Pd−C23 angle in the adjacent position. The P−Pd−O
angles associated with the chelating phosphinosulfonate ligand
in 7 and 8 (∼90°) fall between the values reported for cis-
Table 2. Selected Distances (Å) and Angles (deg) for 7 and
a
8
2
38
[
Pd(2-Ph PC H SO -κ O,P) ] (∼85°)
and [PdMe(2-
2
6
4
3
2
2
39
Ph PC H SO -κ O,P)(C H N-κN)] (∼94−95°). This sug-
gests that the chelate coordination of the Ph PfcSO anion is
complex 6 (Y = N)
2
6
4
3
5
5
−
2
3
param
Pd−P
Pd−O
Pd−Y
Pd−C
P−Pd−O
Y−Pd−C
S−O1
S−O2
S−O3
∠Cp1,Cp2
τ
molecule 1
molecule 2
7 (Y = S)
not compromised by the size and spatial properties of the
ferrocene scaffold.
Otherwise, however, the palladium center and its four
2.2944(6)
2.152(2)
2.142(2)
2.004(2)
89.43(5)
81.92(9)
1.484(2)
1.437(2)
1.445(2)
2.2(2)
2.2626(6)
2.170(2)
2.155(2)
1.979(3)
90.93(4)
81.72(9)
1.487(1)
1.444(2)
1.443(2)
3.3(2)
2.3298(5)
2.153(2)
2.3166(5)
2.015(2)
89.64(4)
82.67(6)
1.485(2)
1.449(2)
1.443(2)
3.8(1)
ligating atoms remain nearly coplanar (within ca. 0.1 Å with
YC
respect to the mean plane). The (L )Pd fragments adopt
approximate envelope conformations with the donor atoms Y
at the tip position. For both complexes, the coordinated S−O
bonds are significantly longer than the remaining, formally S
O bonds. Finally, the ferrocene cylopentadienyl rings in 7 and 8
are tilted by less than 4° and rotated so that their substituents
which are involved in chelate coordination assume positions
roughly halfway between staggered and eclipsed synclinal (cf.
the ideal values: 36 and 72°).
−49.9(2)
40.5(2)
−54.8(2)
a
The parameters are defined as they were for 4 (see footnote to Table
1).
In addition to the neutral complexes with the LYC chelating
ligands, we also prepared the anionic bis(phosphine) complex
trans-(Et NH) [PdCl (Ph PfcSO -κP) ] (9), by reacting com-
prolonged storage under ambient conditions) to produce
defined, solvent-free 9.
Unlike complexes 7 and 8, compound 9 contains a pair of
3
2
2
2
3
2
pound 4 (2 equiv) with [PdCl (MeCN) ] (Scheme 4). This
2
2
complex was conveniently purified by crystallization from
methanol/diethyl ether to afford the red, air-stable stoichio-
metric solvate 9·2MeOH. This compound, however, readily
loses the solvent of crystallization (under vacuum or even upon
equivalent phosphinoferrocene sulfonate anions coordinating as
+
monodentate phosphine ligands and two Et NH counterions.
3
The formation of a bis(phosphine) complex is indicated by the
31
characteristic downfield shift of the P NMR signal (δ 15.6 in
P
D
DOI: 10.1021/acs.organomet.8b00178
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Organometallics
Article
Scheme 4. Synthesis of Complex 9
the NH and OH protons of the proximal counter cations and
the solvent molecules (see Figure 3; N···O1 2.759(2) Å, O1S···
O2 2.791(2) Å).
Catalytic Tests. Considering the hydrophilic nature of
phosphinoferrocene sulfonate 4, we examined this polar ligand
in a Pd-catalyzed Suzuki−Miyaura-type cross-coupling of acyl
43
chlorides with boronic acids to give ketones. Although this
reaction may not seem economical in terms of the cost of the
starting materials or atom efficiency, it offers a valuable
alternative to the conventional acylation reactions because of its
selectivity, functional group tolerance and the fact that both
acyl chlorides and boronic acids are now readily (often
commercially) available. As such, this reaction appears
particularly suitable for the selective, small-scale synthesis of
specifically substituted functional ketones. In addition, the
reaction can be performed under aqueous conditions, which
ensures the solubility of both the organic and inorganic
components, making them available for the coupling reaction.
For initial screening of the factors that might affect the
course of the catalytic reaction, we chose the model coupling
reaction of benzoyl chloride (10a, used in 20 mol % excess)
with 4-methoxyphenylboronic acid (11f), which can be easily
4
0
CDCl ) and by the appearance of typical apparent triplets for
3
3
1
13
the P-coupled1 C NMR signals resulting from virtual
2
31
31
13
41
coupling in the C− P−Pd− P− C AA′X spin system.
In the crystal structure of 9·2MeOH (Figure 3), the
individual components are distributed around the crystallo-
1
monitored by H NMR spectroscopy (Scheme 5). The results
Scheme 5. Coupling Reaction Used for the Initial Screening
Experiments
a
Table 3. Summary of the Screening Experiments
entry
catalyst
base
solvent
NMR yield (%)
1
2
3
4
5
6
9
Na CO3
H O
15
23
40
43
2
2
9/Q*
9
Na CO3
2
H O
2
Na CO3
2
C D
6
6
9/Q*
9
Na CO3
2
C D
6
6
b
Na CO3
2
C D /H O
90 (75)
6
6
2
9/Q*
9
Na CO3
2
C D /H O
89
52
50
48
52
72
79
69
34
16
96
5
6
6
2
c
7
Na CO3
2
C D /H O
6 6 2
c
8
9/Q*
7
Na CO3
2
C D /H O
6 6 2
9
Na CO3
2
C D /H O
6 6 2
1
1
1
1
1
1
1
1
0
1
2
3
4
5
6
7
7/Q*
8
Na CO3
2
C D /H O
6 6 2
Na CO3
2
C D /H O
6 6 2
8/Q*
9
Na CO3
2
C D /H O
6 6 2
Figure 3. View of the structure of 9·2MeOH. Hydrogen bonds are
indicated by dashed lines. Selected distances (Å) and angles (deg):
Pd−Cl 2.3015(5), Pd−P 2.3416(4), Cl−Pd−P 89.30(2), S−O1
K CO3
2
C D /H O
6 6 2
9
NaHCO3
NaOH
C D /H O
6 6 2
9
C D /H O
6 6 2
1
.459(1), S−O2 1.458(1), S−O3 1.448(2), ∠Cp1,Cp2 3.1(1).
9
Na PO4
3
C D /H O
6 6 2
9
NaOAc
C D /H O
6
6
2
graphic inversion centers that coincide with the Pd atoms, as is
18
none
Na
2
CO
3
C
6
D
/H
6
O
2
0
42
common for complexes of this kind. The coordination
geometry of the Pd(II) ion in 9·2MeOH does not significantly
depart from an ideal square-planar geometry because the
imposed symmetry renders the coordination sphere ideally
planar, the Pd−Cl and Pd−P distances are of rather similar
lengths, and finally, the interligand angles differ only negligibly
from the ideal 90° (by ±0.7°). The sulfonate moieties, which
remain uncoordinated, are rotated away from the ligated metal
center (τ = 139.5(1)°) and act as hydrogen bond acceptors for
a
Unless specified otherwise, 4-methoxyphenylboronic acid (11f; 1.0
mmol) and benzoyl chloride (10a; 1.2 mmol) were reacted in the
presence of the specified catalyst (1.0 μmol, 0.1 mol %) and base (1.0
mmol) in 3 mL of the indicated solvent (water or a C D /H O (1/1)
mixture) at 50 °C for 3 h. Some reactions were performed in the
presence of hexadecyltrimethylammonium bromide (Q*) as a phase
transfer reagent (1.0 μmol). The yields are an average of two or three
6
6
2
b
independent runs. Reaction with 0.05 mol % of the catalyst.
c
Reaction performed at 25 °C.
E
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
outlined in Table 3 indicate that considerably better yields of
coupling product 12f (at 0.1 mol % Pd loading and 50 °C)
were obtained in the organic solvent−water mixture than in
either pure organic solvent or water and that the reaction is not
substantially affected by the presence of hexadecyltrimethy-
lammonium bromide as a phase transfer reagent (Table 3,
entries 1−6). Both decreasing the catalyst amount to 0.05 mol
Next, we turned our attention to evaluating the reaction
45
scope. In view of our previous studies, we compared the
efficacy of complementary routes leading to the same
monosubstituted products but from starting materials with
inverted substitution patterns (routes A and B in Scheme 6)
Scheme 6. Reaction Scope Tests Using Complementary
Routes to Ketones 12
%
and lowering the reaction temperature to 25 °C had
detrimental effects on the reaction outcome (note: the coupling
reaction did not proceed in the absence of a Pd catalyst).
Complex 9 performed the best among the Pd(II) complexes
evaluated in this study (Table 3, entries 5, 6, and 9−12) and
was therefore selected for further experiments. The superiority
of this catalyst is difficult to explain. However, tentatively it may
be ascribed to a better stabilization of the catalytic metal center
(
two soft phosphine ligands) and/or its better solubility (or the
active catalyst formed thereof) in the aqueous reaction system
due to the presence of two sulfonate groups per metal center.
In contrast, the presence of more easily leaving L ligands in
YC
complexes 7 and 8 can result in a faster catalytic activation
4
4
under rather stringent conditions (0.1 mol % Pd, 3 h reaction
time). The results summarized in Table 5 indicate that only in
but, simultaneously, also to a faster decomposition. In
addition, these complexes can be expected to be less
hydrophilic than 9.
a
Table 5. Reaction Scope Tests
Of the tested conventional bases, only Na PO afforded a
3
4
better yield of the coupling product than Na CO , which was
yield of 12 (%)
2
3
the base initially chosen (Table 3, entries 13−17). Hence,
entry
R
route A
route B
Na PO was used along with 9 in all following experiments.
3
4
1
2
3
4
5
6
7
8
9
H (a)
36
72
90
87
66
80
61
95
5
Having performed the screening tests in a C D /water
6
6
2-Me (b)
3-Me (c)
4-Me (d)
4-tBu (e)
4-MeO (f)
4-F (g)
10
57
69
47
8
mixture, we turned our attention to identifying a more practical
solvent mixture (Table 4). Surprisingly, replacing C D with its
6
6
a
Table 4. Additional Screening Experiments
entry
catalyst
solvent
yield of 12f (%)
68
>95
87
27
4-Cl (h)
1
2
3
9
9
9
9
9
C D /H O
95
80
80
80
68
15
22
6
6
2
4-NO (i)
2
C H /H O
6
6
2
1
0
4-CN (j)
<5
toluene/H O
2
a
b
4
toluene/H O
The respective boronic acid (11; 1.0 mmol) and benzoyl chloride
10; 1.2 mmol) were reacted in the presence of 9 (1.0 μmol, 0.1 mol
) and Na PO (1.0 mmol) in 3 mL of toluene/water (1/1) at 50 °C
for 3 h. Isolated yields are an average of two independent runs.
Reaction products obtained in low yields were typically contaminated
by unreacted benzoyl chloride, which is not included in the tabulated
yield.
2
c
(
%
5
toluene/H O
2
6
7
[PdCl (MeCN) ]
toluene/H O
3
4
2
2
2
13
toluene/H O
2
a
Unless specified otherwise, 4-methoxyphenylboronic acid (11f; 1.0
mmol) and benzoyl chloride (10a; 1.2 mmol) were reacted in the
presence of the specified catalyst (1.0 μmol Pd, 0.1 mol %) and
Na PO (1.0 mmol) in 3 mL of the indicated solvent (1/1 mixture) at
3
4
some cases did the two routes perform equally well (entries 7
and 8), while more often, one of the routes provided a
considerably better yield than the complementary one. For
substrates bearing 3-Me, 4-Me, and 4-t-Bu groups, the yields
achieved using route A were ∼20−30% higher (in absolute
terms) than those achieved using route B. Even more
pronounced differences between the two routes were observed
for substrates with a 2-Me substituent (where steric effects can
play a role) and especially with a 4-MeO substituent. In
5
0 °C for 3 h. Isolated yields are an average of two independent runs.
b
c
Reaction with 0.2 mol % of catalyst. Reaction performed in air.
nondeuterated counterpart or toluene resulted in reproducibly
lower yields of 12f, which did not increase even when the
catalyst loading was increased to 0.2 mol % (cf. entries 1−4).
Performing the coupling reaction without an inert atmosphere
had a similar negative effect and further decreased the yield of
the coupling product (entry 5).
contrast, benzophenones with 4-NO and 4-CN substituents
2
Further tests nonetheless confirmed the beneficial influence
of the hydrophilic sulfonate groups in 9 for the coupling
reaction in the biphasic system. The model reactions conducted
under the optimized conditions but with [PdCl (MeCN) ] or
could be accessed in better yields using route B, in which the
substituent comes from the acyl chloride coupling partner.
The same trends were noted also for the reactions leading to
the 4,4′-disubstituted products (Table 6; note that the
substrates were chosen to include both easily reacting and
unreactive compounds and those with minimal steric influence
from the substituents). Among the symmetrically disubstituted
products, only 4,4′-dichlorobenzophenone (12hh) and 4,4′-
dimethylbenzophenone (12dd) were obtained in good yields,
2
2
trans-[PdCl (FcPPh ) ] (13), which is an analogue of complex
2
2 2
9
that lacks the sulfonate groups (the synthesis and crystal
structure of this compound in a solvated form are described in
the Supporting Information), both resulted in significantly
lower yields of 12f.
F
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
7
Table 6. Results of the Coupling Reactions Providing 4,4′-
nature (solubility) and possible hemilabile coordination of
the supporting phosphinoferrocene sulfonate ligand rather than
from its peculiar stereoelectronic properties. The Tolman cone
a
Disubstituted Benzophenones 12
X in 4-
4-YC H C(O)Cl (10)
46
47
48
6
4
angle (θ) and the solid angle (Ω) calculated for the anion
XC H B(OH)
6
4
2
−
(
11)
Y = Me (d) Y = MeO (f) Y = Cl (h) Y = NO (i)
Ph PfcSO3 from the structural data determined for 9·2MeOH
2
2
were 182 and 147°, respectively. While the former value (θ) is
Me (d)
MeO (f)
Cl (h)
76
70
86
<5
5
<5
8
94
91
85
83
94
<5
46
identical with that determined for P(t-Bu)3, it is significantly
smaller than the cone angle estimated for phosphinoferrocene
>95
5
49
amide Ph PfcCONHMe (∼200°). In contrast, the value of
NO (i)
0
2
2
a
the solid angle Ω, which represents the minimum steric
The experiments were performed as described for the substrate scope
47
demands, is similar to that of triphenylphosphine (∼145°)
tests (see footnote a to Table 4).
and compares well to the value calculated for the mentioned
49
amide Ph PfcCONHMe (∼150°).
whereas those bearing a pair of methoxy and nitro groups
2
−
The stereoelectronic properties of the anion Ph PfcSO
(12ff,ii) were formed in only trace amounts (<5%). Of the six
2
3
77
31
were further assessed through the Se− P coupling constant
unsymmetrical derivatives, only 4′-methyl-4-chlorobenzophe-
none (12dh) could be obtained in good yields by both routes.
In reactions leading to 4-methoxy-substituted benzophenones,
the reactions involving 4-methoxyphenylboronic acid consis-
tently produced substantially better yields than those using 4-
methoxybenzoyl chloride. The opposite trend holds true for the
coupling reactions providing 4-chloro- and 4-nitro-substituted
compounds. Especially in the case of reactions involving 4-
nitrophenylboronic acid, the yields were consistently very low
1
(
JSeP), which is known to reflect both phosphine basicity and
46,50
1
steric properties (the latter via C−P−C angles).
The J
SeP
value determined for phosphine selenide 14, obtained by
conventional selenylation of 4 with elemental selenium
Scheme 8), was 732 Hz. This value is very similar to that
(
Scheme 8. Synthesis of Phosphine Selenide 14
(
Table 5, the bottom row).
The differences in the yields of the complementary reactions,
which were sometimes quite significant, can be partially
attributed to the different reactivities of the substrates.
However, other factors, such as side reactions (in particular
hydrolysis of the acyl chlorides, which proceed at different rates
for different substrates) and, more importantly, solubility issues
5
0b
(
4-nitrophenylboronic acid is poorly soluble in the solvent
determined for FcP(Se)Ph (731 Hz), suggesting that the
2
mixture used), can also play an important role. From a wider
perspective, the combined results clearly indicate that both
complementary routes should always be considered to obtain
the coupling products in the highest possible yield.
introduced sulfonate moiety does not affect much the donor
ability of the phosphinoferrocene moiety.
CONCLUSION
■
As further exemplified by the results presented in Scheme 7,
the coupling reaction is not suitable for aliphatic substrates,
This report describes the synthesis of a new polar, anionic
phosphinoferrocene sulfonate ligand, which extends the family
of functional ligands structurally related to 1,1′-bis-
(diphenylphosphino)ferrocene (dppf), the archetypal ferrocene
phosphine donor. Two reliable synthetic approaches for the
preparation of this anionic species, which can be conveniently
isolated, stored, and further utilized in the form of the stable
ammonium salt 4, are described and discussed. In addition,
preliminary experiments focused on the coordination behavior
of this hybrid anionic ligand toward Pd(II) ions were carried
out, and as a result, two types of complexes featuring the title
phosphinoferrocene sulfonate anion as either a monodentate P-
donor or an O,P-chelating ligand with the sulfonate moiety also
involved in coordination as a secondary donor group were
prepared. Catalytic tests with the isolated complexes in the Pd-
catalyzed cross-coupling of acyl chlorides with boronic acids in
water/organic solvent biphasic systems to form ketones showed
that bis(phosphine) complex 9 gives rise to the most active
catalyst. Further catalytic experiments aimed at exploring the
scope of this catalytic reaction revealed that the coupling of
aromatic substrates to generate selectively substituted benzo-
phenones is controlled by the substituents on both reaction
partners, which suggests that the careful selection of starting
materials (mainly in terms of possible transposition of the
substituents on the aromatic rings) is essential for obtaining
good yields of the coupling products. The coupling of aliphatic
Scheme 7. Coupling Reactions Involving Aliphatic
Substrates
which generally fail to afford satisfactory yields of the coupling
products (albeit under rather strict conditions). A notable
exception is the reaction of styrylboronic acid (11l) with
benzoyl chloride, which furnished trans-chalcone (12l) in a
good yield (75% isolated).
The catalytic performance of complex 9 and the trends in
reactivity are comparable to those noticed in reactions
mediated by catalysts based on other phosphinoferrocene
4
5
3
donors. Hence, the favorable catalytic properties of the
reagents, especially those where sp carbons are supposed to
particular Pd(II) complex 9 may well arise from the polar
couple, proceeds much less willingly.
G
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
NMR (101 MHz, CDCl ): δ 8.65 (s, CH of HNEt ), 46.09 (s, CH of
EXPERIMENTAL SECTION
3
3
3
2
■
2
HNEt ), 68.96 (s, CH of fc), 71.61 (s, CH of fc), 74.21 (d, J = 13
3
PC
General Considerations. The syntheses were performed under an
1
3
Hz, CH of fc), 75.69 (d, J = 98 Hz, C−P of fc), 75.87 (d, J = 10
PC
PC
argon atmosphere using standard Schlenk techniques and oven-dried
Hz, CH of fc), 94.49 (s, C−SO of fc), 128.20 (d, J = 13 Hz, CH of
51
52
NC
53
SC
54
3
PC
glassware. Compounds 1, 6, [Pd(OAc)(L )]2, [PdCl(L )] ,
4
2
PPh ), 131.19 (d, J = 3 Hz, CH of PPh ), 131.59 (d, J = 11 Hz,
SC
55
2
PC
para
2
PC
and [Pd(OAc)(L )]2 were prepared according to previously
published procedures. Anhydrous dichloromethane, methanol, and
tetrahydrofuran were obtained from an in-house PureSolv MD5
solvent purification system (Innovative Technology, MA, USA).
CHCl3 was dried over CaH2 and distilled under argon. Acetic
anhydride was distilled under argon. Other chemicals (Sigma-Aldrich
and Alfa-Aesar) and solvents (Lach-Ner, Czech Republic) employed
for crystallizations and chromatography were of reagent grade and
were used without further purification. Cation exchange resin (Dowex
1
CH of PPh ), 134.48 (d, J = 87 Hz, Cipso of PPh ). IR (Nujol):
2
PC
2
−1
νmax/cm 3052 (m), 2630 (br m), 2503 (m), 1671 (br w), 1414 (m),
401 (m), 1309 (w), 1246 (vs), 1178 (m), 1170 (m), 1161 (s), 1151
s), 1105 (m) 1072 (m), 1057 (m), 1037 (vs), 1021 (m), 1009 (m),
1
(
9
8
97 (m), 946 (vw), 922 (vw), 901 (w), 891 (w), 827 (m), 817 (m),
07 (m), 794 (w), 767 (m), 716 (s), 703 (m), 697 (m), 653 (vs), 629
(
m), 614 (m), 563 (m), 544 (m), 534 (w), 500 (s), 487 (s), 471 (m),
+
+
4
6
56 (m), 427 (m). ESI+ MS: m/z 102 ([HNEt ] ), 584 ([M + H] ),
3
+
−
85 ([M + HNEt ] ); ESI− MS: m/z 481 ([Ph P(S)fcSO ] ). Anal.
3
2
3
5
0WX4, Sigma-Aldrich) in its protonated form was washed with a
large volume of methanol prior to use. This cation exchanger was used
for all experiments.
Analytical measurements aimed at confirming the identity and
purity of the prepared compounds were performed for bulk samples
isolated as described below. The NMR spectra were recorded at 25 °C
on a Varian UNITY Inova 400 spectrometer. Chemical shifts (δ in
Calcd for C H FeNO PS (583.5): C, 57.63; H, 5.87; N, 2.40.
28
34
3
2
Found: C, 57.56; H, 5.80; N, 2.34.
Deprotection of 3 and Synthesis of 4. Methyl triflate (2.4 mL,
2 mmol) was added to a solution of compound 3 (5.829 g, 10 mmol)
2
in dichloromethane (100 mL), causing the reaction mixture to warm
slightly and change in color from orange to red. After the mixture was
stirred at room temperature for 3 h, the solvent was evaporated under
vacuum at 35 °C. The oily residue was redissolved in dichloromethane
(100 mL) and treated with neat P(NMe ) (2.5 mL, 14 mmol),
1
13
ppm) are given relative to internal tetramethylsilane ( H and C) and
3
1
to external 85% H PO ( P). In addition to the standard notation for
3
4
2
3
5
6
the signal multiplicity, vt and vq are used to distinguish virtual
whereupon the color reverted from red to deep orange. After it was
stirred for 3 h, the mixture was concentrated under vacuum (at 35 °C),
and the residue was dissolved in methanol (50 mL) and transferred to
multiplets arising from the AA′BB′ and AA′BB′X spin systems of the
ferrocene protons at the sulfonate- and PPh -substituted cyclo-
2
pentadienyl rings, respectively (fc = ferrocene-1,1′-diyl). Infrared
a column containing a cation exchange resin (ca. 100 mL of Dowex
spectra were recorded on a Nicolet 6700 FTIR spectrometer over the
+
5
0WX4 in H cycle) in methanol. After it was equilibrated for 30 min,
−1
4
00−4000 cm range. Low-resolution electrospray ionization (ESI)
the column was washed with methanol, and the orange eluate was
concentrated under reduced pressure at 40 °C.
The residue was dried over NaOH overnight before being dissolved
mass spectra were measured with an Esquire 3000 (Bruker)
spectrometer using samples dissolved in HPLC-grade methanol. The
assignment of the observed ions was confirmed by comparison of the
theoretical and experimentally determined isotopic patterns. Elemental
analyses were conducted with a PerkinElmer PE 2400 CHN analyzer.
Synthesis of 4 by Sulfonation of 1. Neat chlorosulfonic acid
in a dichloromethane/methanol/NEt mixture (20/1/1; ca. 5 mL; at 0
3
°
C) and purified by silica gel chromatography with the same mobile
phase as eluent. Three orange bands were collected and concentrated.
The residues were evaporated three times with chloroform and dried
over H SO . The band that eluted first (2.78 g) contained the crude
(
0.73 mL, 11 mmol) was added dropwise to a suspension of
2
4
phosphine sulfide 1 (4.024 g, 10 mmol) in acetic anhydride (50 mL)
with stirring and cooling in a water bath. After the addition was
complete (ca. 5 min), the mixture was stirred at ambient temperature
for 1 h, during which time all of the starting material dissolved to give a
deep green solution. The reaction mixture was then poured onto
crushed ice (100 g) and stirred for another 1 h. The obtained cloudy
triethyl(methyl)ammonium salt of acid V, the second band (5.93 g)
contained salt 4 contaminated by another triethylammonium salt
(presumably (Et NH)Cl), and the third band contained crude
3
compound 5 (1.18 g). The first and second fractions were combined
and chromatographed again through a cation exchange resin and silica
gel as described above to afford crude salt 4 (4.93 g) as the first
fraction and compound 5 as the second fraction (0.95 g). The crude 4
̈
orange mixture was filtered through a Buchner funnel (which was
washed with water and acetic acid), and the filtrate was evaporated
under vacuum at 40 °C. The orange solid residue was evaporated three
times with dichloromethane (100 mL) and then stored over NaOH in
a desiccator overnight to remove residual acetic acid and acetic
anhydride.
containing (Et NH)Cl was dissolved in hot dichloromethane (7 mL;
3
with sonication), and the solution was diluted with hot ethyl acetate
(70 mL). Slow cooling to 4 °C furnished orange crystals of the pure
salt, which were isolated by suction filtration, washed with ethyl
acetate, and dried under vacuum. Yield of 4: 2.167 g (39%), rusty
orange, crystalline solid.
Fractions containing mostly zwitterionic compound 5 were
combined and rechromatographed over silica gel with a dichloro-
The crude product was mixed with chloroform (100 mL), and the
stirred mixture was treated with triethylamine (15 mL) while being
cooled in an ice bath (30 min). Crude salt 3 obtained after evaporation
of the solvent was twice dissolved in chloroform, evaporated, and then
purified by silica gel chromatography using a dichloromethane/
methane/methanol/NEt mixture (20/1/1). The main band from the
3
product was collected and concentrated. The solid residue was
methanol/NEt mixture (20/1/1) as the eluent. The main orange
evaporated three times with chloroform, dried over H SO , and finally
3
2
4
band (without the yellow forerun and the red tail) was collected and
evaporated. The solid product was evaporated three times with
chloroform and dried over H SO overnight. Then, it was dissolved in
crystallized by dissolving in dichloromethane (30 mL), adding hot
ethyl acetate (30 mL), and slowly cooling to 4 °C. The crystalline
product was isolated using the procedure described for 4, which
2
4
dichloromethane (50 mL), and the solution was diluted with hot ethyl
acetate (50 mL), treated with charcoal, filtered, and evaporated. Next,
the residue was dissolved in hot dichloromethane (5 mL), and the
solution was diluted with hot ethyl acetate (50 mL). The product,
which crystallized upon slow cooling to 4 °C, was isolated by filtration,
washed with ethyl acetate, and dried under vacuum to give analytically
pure salt 3. Yield: 4.463 g (76%), orange crystalline solid.
yielded compound 5 as a rusty brown, crystalline solid (0.364 g, 8%).
1
Analytical Data for 4. Mp: 157 °C (CH
Cl
/AcOEt). H NMR
2
2
3
(400 MHz, CDCl
): δ 1.34 (t, JHH = 7.3 Hz, 9 H, CH
of HNEt
), 4.05 (vt, J′ =
1.9 Hz, 2 H, fc), 4.24 (vq, J′ = 1.9 Hz, 2 H, fc), 4.51 (vt, J′ = 1.9 Hz, 2
H, fc), 4.68 (vt, J′ = 1.7 Hz, 2 H, fc), 7.28−7.38 (m, 10 H, PPh ),
): δ −16.5
of HNEt ),
), 68.32 (s, CH of fc), 70.33 (s, CH of fc),
),
3
3
3
3
4
3.12 (dq, JHH = 7.3, JHH = 4.8 Hz, 6 H, CH of HNEt
2 3
2
31
1
10.52 (br s, 1 H, HNEt
). P{ H} NMR (162 MHz, CDCl
(s). C{ H} NMR (101 MHz, CDCl ): δ 8.63 (s, CH
46.03 (s, CH of HNEt
74.35 (d, JPC = 15 Hz, CH of fc), 74.54 (d, JPC = 4 Hz, CH of fc),
3
3
1
3
13
1
H NMR (400 MHz, CDCl ): δ 1.34 (t, J = 7.3 Hz, 9 H, CH of
3
3
3
3
HH
3
3
4
HNEt ), 3.11 (br dq, J = 7.3 Hz, J = 2.6 Hz, 6 H, CH of
2
3
3
HH
HH
2
2
3
HNEt ), 4.27 (vt, J′ = 1.9 Hz, 2 H, fc), 4.50 (vt, J′ = 1.9 Hz, 2 H, fc),
3
1
4
7
.58 (vq, J′ = 2.0 Hz, 2 H, fc), 4.81 (vq, J′ = 1.8 Hz, 2 H, fc), 7.39−
76.70 (d, JPC = 6 Hz, C−P of fc), 94.01 (s, C−SO
3
of fc), 128.10 (d,
3
.49 (m, 6 H, PPh ), 7.67−7.74 (m, 4 H, PPh ), 10.38 (br s, 1 H,
J
PC = 7 Hz, CHmeta of PPh
2
), 128.43 (s, CHpara of PPh ), 133.45 (d,
2
2
2
31
1
13
1
2J = 20 Hz, CHortho of PPh ), 138.99 (d, J = 10 Hz, Cipso of PPh2).
1
HNEt ). P{ H} NMR (162 MHz, CDCl ): δ 42.0 (s). C{ H}
3
3
PC 2 PC
H
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
IR (Nujol): νmax/cm− 3065 (m), 2676 (br m), 2506 (m), 1672 (br
1
produced rusty orange crystals, which were isolated by suction
filtration, washed with diethyl ether, and dried under vacuum. Yield of
7: 44.7 mg (65%).
w), 1397 (m), 1340 (w), 1308 (m), 1242 (vs), 1189 (m), 1163 (vs),
155 (s), 1089 (m), 1058 (m), 1039 (vs), 1010 (m), 922 (w), 898
w), 882 (vw), 854 (w), 827 (m), 811 (m), 754 (m), 748 (m), 701
m), 653 (vs), 563 (m), 534 (w), 524 (m), 494 (s), 458 (m), 442 (m),
1
1
4
(
(
4
5
H NMR (400 MHz, CDCl ): δ 2.96 (d, J = 2.9 Hz, 6 H, NMe2),
3 PH
4
4.06 (br d, J = 2.0 Hz, 2 H, NCH ), 4.07 (vt, J′ = 2.0 Hz, 2 H, fc),
PH
2
+
+
32 (w). ESI+ MS: m/z 102 ([HNEt ] ), 451 ([M − NEt + H] ),
4.41 (vt, J′ = 2.0 Hz, 2 H, fc), 4.70 (dvt, J = 1.9, 0.8 Hz, 2 H, fc), 4.86
(dvt, J′ = 2.9, 1.9 Hz, 2 H, fc), 5.86 (ddd, J = 7.9, 6.5, 1.2 Hz, 1 H,
C H ), 6.23 (br td, J = 7.7, 1.6 Hz, 1 H, C H ), 6.72 (td, J = 7.3, 1.1
3
3
+
−
52 ([M + H] ); ESI− MS: m/z 449 ([Ph PfcSO ] ). Anal. Calcd for
2
3
C H FeNO PS (551.4): C, 60.98; H, 6.21; N, 2.54. Found: C, 60.89;
2
8
34
3
6
4
6
4
H, 6.11; N, 2.45.
Hz, 1 H, C H ), 6.88 (br dd, J = 7.4, 1.6 Hz, 1 H, C H ), 7.27−7.33
6
4
6
4
1
Analytical Data for 5. H NMR (400 MHz, dmso-d ): δ 3.08 (d,
(m, 4 H, PPh ), 7.36−7.41 (m, 2 H, PPh ), 7.52−7.58 (m, 4 H, PPh ).
6
2
2
2
2JPH = 14.5 Hz, 3 H, PMe), 4.01 (vt, J′ = 1.9 Hz, 2 H, fc), 4.30 (vt, J′ =
31 1 13 1
P{ H} NMR (162 MHz, CDCl ): δ 28.4 (s). C{ H} NMR (101
3
3
1
.9 Hz, 2 H, fc), 4.77 (vq, J′ = 1.9 Hz, 2 H, fc), 4.94 (vq, J′ = 1.9 Hz, 2
MHz, CDCl ): δ 50.06 (d, J = 2 Hz, NMe ), 69.79 (s, CH of fc),
3 PC 2
3
1
1
1
3
H, fc), 7.67−7.73 (m, 4 H, PPh ), 7.76−7.84 (m, 6 H, PPh ). P{ H}
NMR (162 MHz, dmso-d ): δ 24.5 (s). C{ H} NMR (101 MHz,
70.31 (s, CH of fc), 72.08 (d, JPC = 52 Hz, C−P of fc), 72.13 (d, JPC
2
2
1
3
1
3
= 3 Hz, NCH
), 73.33 (d, JPH = 8 Hz, CH of fc), 77.18 (d, partly
),
), 124.97 (d, JPC = 6
), 128.16 (d, JPC = 11 Hz, CH of PPh ), 130.56 (d,
), 132.77 (d, JPC = 53 Hz, Cipso of PPh ),
134.34 (d, JPC = 12 Hz, CH of PPh ), 136.88 (d, J = 11 Hz, CH of
6
2
1
1
dmso-d ): δ 6.67 (d, J = 59 Hz, PMe), 60.78 (d, J = 103 Hz, C−
overlapping with the solvent signal, CH of fc), 92.95 (s, C−SO
3
6
PC
PC
4
P of fc), 69.35 (d, JPC = 19 Hz, 2 CH of fc), 74.33 (d, JPC = 13 Hz, CH
of fc), 75.88 (d, J = 11 Hz, CH of fc), 98.66 (s, C−SO of fc), 122.59
122.54 (s, CH of C
Hz, CH of C
H ), 123.98 (s, CH of C H
6 4 6 4
H
PC
3
6
4
2
1
3
4
1
(
d, J = 90 Hz, C of PPh ), 129.57 (d, J = 13 Hz, CH of
J
PC = 2 Hz, CHpara of PPh
2
2
PC
ipso
2
PC
meta
2
4
3
PPh ), 132.24 (d, J = 11 Hz, CHortho of PPh ), 134.15 (d, J = 3
2
PC
2
PC
2
PC
−
1
2
3
Hz, CHpara of PPh ). IR (Nujol): νmax/cm 3091 (m), 2723 (br w),
C H ), 144.50 (d, J = 4 Hz, Cipso of C H ), 148.00 (d, J = 2 Hz,
2
6 4 PC 6 4 PC
−1
2
1
670 (br w), 1415 (w), 1405 (w), 1326 (w), 1315 (m), 1230 (vs),
195 (vs), 1184 (s), 1173 (s), 1122 (m), 1114 (m), 1077 (w), 1052
Cipso of C H ). IR (Nujol): νmax/cm 1586 (vw), 1407 (vw), 1306
6 4
(w), 1256 (vs), 1196 (m), 1181 (m), 1156 (vs), 1117 (vw), 1097 (m),
1051 (m), 1031 (s), 1003 (s), 978 (vw), 935 (w), 888 (w), 867 (w),
841 (m), 822 (m), 813 (m), 755 (vw), 744 (s), 701 (m), 694 (m), 657
(m), 642 (s), 595 (vw), 579 (w), 544 (m), 529 (m), 498 (m), 487 (s),
(
(
(
(
m), 1042 (vs), 1013 (m), 999 (w), 938 (vw), 914 (m), 893 (m), 882
m), 871 (w), 848 (m), 827 (m), 815 (w), 787 (w), 760 (m), 749
m), 720 (m), 696 (m), 649 (vs), 624 (vw), 615 (vw), 554 (w), 538
m), 500 (m), 491 (s), 473 (m), 449 (w). ESI+ MS: m/z 465 ([M +
+
472 (m), 454 (w), 438 (w). ESI+ MS: m/z 690 ([M + H] ), 712 ([M
+
+
+
+
+
H] ), 487 ([M + Na] ), 503 ([M + K] ); ESI− MS: m/z 449 ([M −
+ Na] ), 728 ([M + K] ). Anal. Calcd for C H FeNO PPdS (689.8):
31 30 3
−
H] ). Anal. Calcd for C H FeO PS·0.1CH Cl (472.8): C, 58.68; H,
C, 53.97; H, 4.38; N, 2.03. Found: C, 53.91; H, 4.39; N, 1.89.
23
21
3
2
2
SC
2
4
.52. Found: C, 58.44; H, 4.37.
Synthesis of [(L )Pd(Ph PfcSO -κ O,P)] (8). Compound 4 (55.1
2
3
SC
Synthesis of 4 by Lithiation of 6. A stirred solution of bromide 6
4.766 g, 10 mmol, purity 95%) in anhydrous THF (80 mL) was
cooled in a dry ice/ethanol bath to ca. −78 °C and treated with LiBu
4.4 mL 2.5 M in hexanes, 11 mmol). After it was stirred for 15 min,
the solution was poured onto solid Me N·SO (1.672 g, 12 mmol) in
mg, 0.10 mmol) and [Pd(OAc)(L )] (30.2 mg, 0.50 mmol) were
2
(
reacted in chloroform (3 mL) as described for complex 7. Evaporation
of the chloroform and crystallization from ethyl acetate (10 mL) and
hexane (15 mL; liquid phase diffusion) afforded orange-brown crystals,
which were isolated by filtration, washed with hexane and pentane, and
dried under vacuum to afford analytically pure 8. Yield: 54.8 mg
(79%).
(
3
3
another flask attached to the reaction vessel by a glass connecting tube.
The resulting orange suspension was stirred at −78 °C for 15 min and
then at room temperature overnight (16 h; all of the Me N·SO
dissolved during this time). The orange reaction mixture was
concentrated under vacuum, leaving a residue, which was chromato-
graphically purified (silica gel, CH Cl ). After the first band containing
Like the previous procedure, the same product (8) was also isolated
3
3
SC
from the reaction of [PdCl(L )] (27.9 mg, 0.050 mmol) with 4
2
(55.1 mg, 0.10 mmol) in CHCl (3 mL) and crystallization from
3
methanol (2 mL) and diethyl ether (8 mL). Yield of 8: 43.8 mg (63%).
2
2
1
4
FcPPh (1.210 g, 33%) was removed, the eluent was gradually changed
H NMR (400 MHz, CDCl ): δ 2.68 (d, J = 3.8 Hz, 3 H, SMe),
2
3 PH
to dichloromethane/methanol (5/1), which led to the development of
an orange band. This band was collected and concentrated. The
residue (4.77 g) was dissolved in methanol and passed through the
cation exchanger. The eluate was concentrated, and the residue was
dissolved in a minimum of a CH Cl /MeOH/NEt mixture (20/1/1,
4.11 (br vt, J′ = 1.9 Hz, 2 H, fc), very br s centered at 4.2 (2 H, SCH ),
2
4.47 (br s, 2 H, fc), 4.74 (br s, 2 H, fc), 4.91 (br s, 2 H, fc), 6.10 (br td,
J = 7.7, 1.1 Hz, 1 H, C H ), 6.18 (br td, J = 7.6, 1.6 Hz, 1 H, C H ),
6
4
6
4
6.65 (td, J = 7.3, 1.2 Hz, 1 H, C H ), 6.89 (br dd, J = 7.5, 1.7 Hz, 1 H,
6
4
C
H
), 7.27−7.33 (br m, 4 H, PPh
), 7.36−7.42 (br m, 2 H, PPh
). P{ H} NMR (162 MHz, CDCl ): δ 26.2 (s).
C{ H} NMR (101 MHz, CDCl ): δ 20.11 (d, J = 2 Hz, SMe),
),
2
2
3
6
4
2
2
31
1
ca. 5 mL) at 0 °C and then chromatographed over silica gel using the
same solvent mixture as the eluent. The main orange band was
collected and concentrated, and the residue was evaporated with
chloroform three times and dried over H SO .
7.52 (br s, 4 H, PPh
2
3
13
1
3
3
PC
3
45.55 (d, J = 1 Hz, SCH ), 69.82 (s, CH of fc), 70.24 (s, CH of fc),
71.90 (d, J = 49 Hz, C−P of fc), 73.44 (d, J = 8 Hz, CH of fc),
77.22 (d, partly overlapping with the solvent signal, CH of fc), 92.97
PC
2
1
3
2
4
PC
PH
Crude 4 containing some (Et NH)Cl was dissolved in warm
3
CH Cl (5 mL) under sonication. The solution was treated with
(s, C−SO of fc), 123.88 (s, CH of C H ), 124.45 (s, CH of C H ),
2
2
3
6
4
6
4
4
charcoal, diluted with ethyl acetate (50 mL), and cooled to room
125.49 (d, J = 6 Hz, CH of C H ), 128.23 (d, J = 11 Hz, CH of
PPh ), 130.63 (s, CH of PPh ), 132.13 (d, J = 51 Hz, C of
2 para 2 PC ipso
PC 6 4 PC
1
temperature. The colorless crystals of (Et NH)Cl that had formed
3
3
were isolated by decantation, and the mother liquor was evaporated.
The residue was crystallized from dichloromethane and ethyl acetate
PPh ), 134.26 (d, J = 11 Hz, CH of PPh ), 138.94 (d, J = 13 Hz,
2 PC 2 PC
2
3
CH of C H ), 145.69 (d, J = 1 Hz, Cipso of C H ), 150.03 (d, J =
PC
1 Hz, Cipso of C H ). IR (Nujol): νmax/cm 1735 (w), 1577 (vw),
6
4
PC
6
4
−1
(
5 + 50 mL) as described above, and pure 4 (1.663 g, 30%) was
6 4
isolated by suction filtration.
1317 (w), 1310 (w), 1293 (vw), 1250 (vs), 1195 (s), 1187 (m), 1170
(m), 1159 (m), 1148 (vs), 1111 (vw), 1097 (m), 1071 (vw), 1063
(w), 1055 (vw), 1033 (s), 1019 (m), 1002 (s), 969 (m), 940 (w), 925
(vw), 888 (vw), 859 (vw), 847 (w), 837 (m), 825 (m), 807 (w), 761
(m), 741 (s), 704 (m), 695 (m), 657 (m), 639 (s), 579 (w), 540 (m),
533 (m), 501 (m), 490 (s), 470 (m), 451 (w), 437 (w). ESI+ MS: m/z
NC
2
Synthesis of [(L )Pd(Ph PfcSO -κ O,P)] (7). A solution of salt 4
2
3
(
[
55.1 mg, 0.10 mmol) in chloroform (2 mL) was added to
NC
Pd(OAc)(L )]2 (30.0 mg, 0.050 mmol) dissolved in the same
solvent (1 mL), and the mixture was stirred for 3 h and then
evaporated under vacuum. The residue was dissolved in ethyl acetate
+
+
(
5 mL) and crystallized by adding hexane (20 mL) as a top layer.
715 ([M + Na] ), 731 ([M + K] ). Anal. Calcd for C H FeO PPdS
30 27 3 2
Crystals of 7, which formed upon mixing of the solvents during several
days, were isolated by filtration, washed with hexane and pentane, and
dried under vacuum. Yield: 57.5 mg (83%), orange, crystalline solid.
(692.9): C, 52.00; H, 3.93. Found: C, 51.73; H, 3.97.
Synthesis of (Et NH) [PdCl (Ph PfcSO -κP) ] (9). A solution of
compound 4 (275 mg, 0.50 mmol) in chloroform (2 mL) was added
3
2
2
2
3
2
Alternatively, 4 (55.1 mg, 0.10 mmol) and [PdCl(LNC)] (27.6 mg,
to [PdCl (MeCN) ] (65 mg, 0.25 mmol) dissolved in the same
2
2
2
0
.050 mmol) were reacted in CHCl (3 mL) for 3 h. Evaporation and
solvent (1 mL), and the reaction mixture was stirred for 1 day. The
product precipitated as a red solid, which was then stored at −20 °C
3
recrystallization from methanol (2 mL) and diethyl ether (8 mL)
I
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
overnight. The precipitate was isolated by filtration, washed with
temperature and terminated by the addition of saturated aqueous
CHCl (1 mL), and dissolved in methanol (3 mL). The solution was
NaHCO (9 mL). The mixture was extracted with diethyl ether (20
3
3
filtered through a PTFE syringe filter (0.25 μm pore size) and layered
with a minimum of a 1/1 methanol/diethyl ether mixture and then
with diethyl ether (20 mL). The red crystals (9·2MeOH), which
formed within several days, were isolated by filtration, washed with
diethyl ether, and dried under vacuum to afford unsolvated 9. Yield of
mL), and the organic layer was separated, washed with saturated
aqueous NaHCO3 and NaCl, dried over MgSO , and finally
4
concentrated onto chromatographic silica gel. The product (pre-
adsorbed on the silica gel) was isolated by silica gel column
chromatography using ethyl acetate/hexane as the eluent (1/5, 1/10,
or 1/20 depending on the product polarity). The yields given in the
text are an average of two independent runs (note: details of the
screening reactions are available in the Supporting Information).
X-ray Crystallography. The full-set diffraction data (±h, ±k, ±l;
9
: 244 mg (76%), brick red, crystalline powdery solid.
1
3
H NMR (400 MHz, CDCl ): δ 1.33 (t, J = 7.3 Hz, 9 H, CH of
3
HH
3
3
HNEt ), 3.11 (q, J = 7.3 Hz, 6 H, CH of HNEt ), 4.68 (br vt, J′ =
3
HH
2
3
1
7
.8 Hz, 2 H, fc), 4.72−4.75 (br m, 6 H, fc), 7.33−7.42 (m, 6 H, PPh ),
2
31 1
.59−7.64 (m, 4 H, PPh ), 10.36 (br s, 2 H, HNEt ). P{ H} NMR
θmax = 27.5°, data completeness ≥99.6%) were recorded on a Bruker
2
3
13
1
(
162 MHz, CDCl ): δ 15.6 (s). C{ H} NMR (101 MHz, CDCl ): δ
Apex II CCD diffractometer (compounds 4, 7, 8, and 9·2MeOH) or a
Bruker D8 Venture Kappa Duo diffractometer equipped with a
PHOTON 100 detector and a IμS 3.0 microfocus source (compounds
3
3
8
7
4
.67 (s, CH of HNEt ), 46.10 (s, CH of HNEt ), 69.10 (s, CH of fc),
3 3 2 3
1.71 (vt, JPC = 27 Hz, C−P of fc), 72.20 (s, CH of fc), 75.55 (vt, J
=
PC
2
Hz, CH of fc), 76.67 (vt, J = 5 Hz, CH of fc), 94.70 (s, C−SO of
3, 5, and 13·2CHCl ). All measurements were performed at 120 or
3
PC
3
fc), 127.72 (vt, JPC = 5 Hz, CH of PPh ), 130.19 (s, CH of PPh ),
150 K (Cryostream cooler, Oxford Cryosystems) using Mo Kα
radiation (λ = 0.71073 Å). The data were corrected for absorption by
the methods included in the diffractometer software.
2
para
2
1
31.25 (vt, JPC = 25 Hz, C of PPh ), 134.14 (vt, J = 6 Hz, CH of
2
ipso 2 PC
−1
PPh ). IR (Nujol): νmax/cm 3537 (br m), 3462 (br m), 2706 (br m),
57
2
530 (br w), 1629 (br vw), 1300 (w), 1220 (s), 1180 (br vs), 1097
The structures were solved by direct methods (SHELXS97 or
58
2
(
(
(
m), 1057 (m), 1043 (vs), 1013 (m), 999 (w), 893 (vw), 847 (m), 838
m), 821 (m), 750 (m), 709 (m), 698 (m), 652 (vs), 626 (m), 557
SHELXT-2014 ) and refined by full-matrix least squares based on F
59
(SHELXL-2017 ). All non-hydrogen atoms were refined with
anisotropic displacement parameters. The NH hydrogens were located
on the difference density maps and refined as riding atoms with Uiso
assigned to 1.2 times the Ueq value of their bonding atom. Hydrogen
w), 540 (m), 502 (vs), 474 (s), 464 (m), 437 (w), 425 (w). ESI+ MS:
+
m/z 1005 ([M − 2HNEt − 2Cl + H] ), 1027 ([M − 2HNEt − 2Cl
+
3
3
+
+
Na] ), 1043 ([M − 2HNEt − 2Cl + K] ), 1106 ([M − HNEt −
3
3
+
−
2
Cl] ); ESI− MS: m/z 1039 ([M − 2HNEt − Cl] ). Anal. Calcd for
atoms bonded to carbons (CH ) were included in their calculated
n
3
C H Cl Fe N O P PdS ·2MeOH (1344.3): C, 51.82; H, 5.70; N,
2
positions and refined similarly. Disordered solvating ethyl acetate
molecules in the structure of 7 were treated as diffuse scattering using
5
6
68
2
2
2
6
2
2
.08. Found: C, 51.69; H, 5.38; N, 2.08.
6
0
Synthesis of Compound 14. Compound 4 (113 mg, 0.20 mmol)
PLATON SQUEEZE. Relevant crystallographic data and structural
refinement parameters are given in the Table S1 in the Supporting
Information.
and gray selenium (17 mg, 0.22 mmol) were reacted in dichloro-
methane (10 mL) overnight. The solvent was evaporated under
vacuum, and the residue was purified by chromatography over silica gel
6
1
PLATON was used for the graphical presentation of the
structures and all geometric calculations. The numerical values are
rounded with respect to their estimated deviations (ESDs) and given
to one decimal place. The parameters related to atoms in constrained
positions are given without ESDs.
using dichloromethane/methanol/NEt (20/1/1) as the eluent. The
3
eluate was evaporated, dissolved in chloroform, and evaporated. This
procedure was repeated once again with dichloromethane and ethyl
acetate (2 mL each). Next, the crude product was dissolved in a
minimum of dichloromethane (few drops) and mixed with hot ethyl
acetate (∼2 mL). The crystalline product, which separated upon
cooling, was filtered off, washed with ethyl acetate and pentane, and
dried under vacuum. Yield of 14: 107 mg (85%), orange crystalline
solid.
ASSOCIATED CONTENT
■
*
S
Supporting Information
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00178.
1
3
H NMR (400 MHz, CDCl ): δ 1.34 (t, J = 7.3 Hz, 9 H, CH of
3
HH
3
3
4
HNEt ), 3.11 (dq, J = 7.3, J = 4.2 Hz, 6 H, CH of HNEt ),
3
HH
HH
2
3
4
=
.31 (vt, J′ = 1.9 Hz, 2 H, fc), 4.51 (vt, J′ = 1.9 Hz, 2 H, fc), 4.59 (vq, J′
Additional structural drawings including displacement
ellipsoid plots of all structurally characterized com-
pounds, summary of the crystallographic and structure
refinement parameters, synthesis and crystal structure of
1.9 Hz, 2 H, fc), 4.84 (vq, J′ = 1.9 Hz, 2 H, fc), 7.37−7.75 (m, 10 H,
31
1
PPh ), 10.40 (br s, 1 H, HNEt ). P{ H} NMR (162 MHz, CDCl ): δ
3
2
3
3
77
1
13
1
2.2 (s with Se satellites, J = 732 Hz). C{ H} NMR (101 MHz,
SeP
CDCl ): δ 8.65 (s, CH of HNEt ), 46.09 (s, CH of HNEt ), 69.00
3
3
3
2
3
2
(
s, CH of fc), 71.97 (s, CH of fc), 74.61 (d, J = 13 Hz, CH of fc),
PC
1
3
13·2CHCl
3
, characterization data for the coupling
7
9
1
4.67 (d, J = 89 Hz, C−P of fc), 76.04 (d, J = 10 Hz, CH of fc),
PC
PC
products 12, and NMR spectra (PDF)
4.51 (s, C−SO of fc), 128.21 (d, J = 13 Hz, CH of PPh2),
3
PC
4
31.24(d, J = 3 Hz, CH of PPh ), 132.03 (d, J = 11 Hz, CH of
PC
para
2
PC
Accession Codes
1
−1
PPh ), 133.37 (d, J = 79 Hz, Cipso of PPh ). IR (Nujol): νmax/cm
2
PC
2
CCDC 1832482−1832488 contain the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/data_request/cif, or by email-
ing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
2
(
1
671 (br m), 2633 (br m), 2504 (br m), 1413 (w), 1400 (w), 1307
w), 1292 (vw), 1246 (vs), 1178 (s), 1171 (s), 1162 (s), 1151 (s),
101 (m), 1072 (w), 1057 (m), 1037 (vs), 1022 (m), 1009 (m), 998
(
(
w), 891 (vw), 827 (m), 817 (w), 794 (vw), 765 (m), 706 (m), 699
m), 654 (s), 631 (w), 572 (s), 538 (m), 499 (s), 478 (s), 461 (m).
+
ESI+ MS: m/z 102 ([HNEt ] ); ESI− MS: m/z 529 ([Ph P(Se)-
fcSO ] ). Anal. Calcd for C H FeNO PSSe (630.4): C, 53.35; H,
3
2
−
3
28 34
3
5
.44; N, 2.22. Found: C, 52.98; H, 5.28; N, 2.21.
Catalytic Experiments: Reaction Scope Tests. A Schlenk tube
AUTHOR INFORMATION
■
*
was charged successively with the appropriate boronic acid (1.0
mmol), acyl chloride (1.2 mmol), sodium phosphate (164 mg, 1.0
mmol), and a stirring bar, flushed with argon, and sealed with a rubber
septum. Toluene (1.5 mL) was introduced, and the reaction flask was
transferred to an oil bath maintained at 50 °C. Next, the catalyst (9;
Corresponding Author
̌
E-mail for P.S: petr.stepnicka@natur.cuni.cz.
ORCID
̌
̌ ̌
Petr Stepnicka: 0000-0002-5966-0578
1
.28 mg, 1.0 μmol) dissolved with sonication in degassed water (1.5
Notes
mL) was introduced, and the reaction was allowed to proceed with
continuous stirring for 3 h. The resulting mixture was cooled to room
The authors declare no competing financial interest.
J
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Same, U.S. Patent 20070049712, March 1, 2007. (b) Rezabal, E.; Asua,
J. M.; Ugalde, J. M. Organometallics 2015, 34, 373−380 and references
cited therein.
ACKNOWLEDGMENTS
■
This research was supported by the Grant Agency of Charles
University (project no. 8415) and by the Charles University
Research Center program no. UNCE/SCI/014. The authors
(15) Chen, M.; Yang, B.; Chen, C. Angew. Chem., Int. Ed. 2015, 54,
1
2
5520−15524. (b) Yang, B.; Pang, W.; Chen, M. Eur. J. Inorg. Chem.
thank Assoc. Prof. Filip Uhlık from the Department of Physical
́
017, 2017, 2510−2514.
and Marcomolecular Chemistry, Faculty of Science, Charles
University, for calculating the cone and solid angles for
(16) For recent examples, see: (a) Zab
Step
Císaro
́
ransky,
́
M.; Císaro
̌
va,
́
I.;
̌
̌
̌
nick
̌
a, P. Dalton Trans. 2015, 44, 14494−14506. (b) Skoch, K.;
−
̌
̌
Ph PfcSO .
̌
va,
́
I.; Step
̌
nicka, P. Chem. - Eur. J. 2015, 21, 15998−16004.
2
3
̌
̌
I.; Step
̌
(c) Skoch, K.; Císaro
̌
va,
́
nick
̌
a, P. Organometallics 2015, 34,
̌
̌
̌
1
942−1956. (d) Skoch, K.; Uhlík, F.; Císaro
̌
va,
́
I.; Step
nick
̌
a, P. Dalton
va, I.;
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2
4
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(
19) (a) Podlaha, J.; Ste
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(
(
(
20) Knox, G. R.; Pauson, P. L. J. Chem. Soc. 1958, 692−696.
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1
21) Analytical data for Ph P(S)fcSO H. H NMR (400 MHz, dmso-
2
3
d ): δ 3.97 (vt, J′ = 1.9 Hz, 2 H, fc), 4.18 (vt, J′ = 1.9 Hz, 2 H, fc), 4.46
6
(
6
vq, J′ = 1.9 Hz, 2 H, fc), 4.65 (vq, J′ = 1.9 Hz, 2 H, fc), 7.50−7.60 (m,
(
6) Electrochemical studies indicated that the oxidation of the
31 1
H, PPh ), 7.65−7.71 (m, 4 H, PPh ). P{ H} NMR (162 MHz,
13 1
ferrocene unit in ferrocene phosphines is followed by chemical steps
that ultimately lead to the formation of phosphine oxides or other
decomposition products. See ref 19a.
2
2
dmso-d ): δ 41.6 (s). C{ H} NMR (101 MHz, dmso-d ): δ 68.28 (s,
CH of fc), 70.00 (s, CH of fc), 73.29 (d, J = 13 Hz, CH of fc),
7
6
6
2
PC
3
1
5.46 (d, J = 10 Hz, CH of fc), 74.42 (d, J = 98 Hz, C-P of fc),
(
7) The sulfonation of triferrocenylphosphine oxide was reported to
PC PC
9
7.47 (s, C-SO of fc), 128.32 (d, J = 12 Hz, CH of PPh ), 131.00
provide trisulfonic acid OP(fcSO H) : Nesmeyanov, A. N.;
3
PC
2
3
3
4
(d, JPC = 11 Hz, CH of PPh ), 131.32 (d,
̧
JPC = 3 Hz, CH of PPh2),
Kursanov, D. N.; Vil’chevskaya, V. D.; Kochetkova, N. S.; Setkina,
V. N.; Novikov, Yu. N. Dokl. Akad. Nauk SSSR 1965, 160, 1090−1092.
2
1
1
34.08 (d, J = 86 Hz, C of PPh ). HR MS (ESI+): calcd for
PC
ipso
2
+
̌
C H FeO PS ([M + H] ), 482.9935; found, 482.9931. HR MS
(ESI−): calcd for C H FeO PS ([M − H] ), 480.9790; found,
4
(
7
2
(
3
(
(
8) (a) Schulz, J.; Císaro
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3
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̌
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(
̈
(
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(24) Methylation of the sulfonate group of acid 3 could generate yet
(
4
another alkylating agent (viz., RSO
3
Me).
can be inferred from the H NMR
spectra of the reaction mixture, which showed the following signals (in
+
1
(25) The presence of MeNEt
3
3
CDCl
NCH
): δ 1.35 (t, JHH = 7.3 Hz, 3 H, NCH
CH
).
), 3.12 (s, 1 H,
3
2
3
3
1
(
438−1449.
14) In addition to compounds with conventional phosphine
substituents, a ferrocenylated IV-type compound, 2-Fc PC H SO H,
3
), 3.45 (q, JHH = 7.3 Hz, 2 H, NCH
2
CH
3
(26) Two equivalents of MeOTf is necessary to successfully
methylate the phosphine sulfide because of the competitive alkylation
2
6
4
3
has also been reported: (a) Allen, N. T.; Goodal, B. L.; McIntosh III,
of the HNEt cation. The subsequent desulfuration can be achieved
3
L. H. Substantially Linear Polymers and Methods of Making and Using
with only 1 equiv of P(NMe ) .
2
3
K
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
(
27) Analytical data for Ph PfcSO H (V). H NMR (400 MHz,
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51−54. (b) Muller, A.; Otto, S.; Roodt, A. Dalton Trans. 2008, 650−
657.
2
3
dmso-d ): δ 3.91 (vt, J′ = 1.8 Hz, 2 H, fc), 4.10 (br d, J′ = 1.6 Hz, 2 H,
6
fc), 4.22 (vt, J′ = 1.9 Hz, 2 H, fc), 4.50 (vt, J′ = 1.7 Hz, 2 H, fc), 7.27−
31
1
7
.39 (m, 10 H, PPh ). P{ H} NMR (162 MHz, dmso-d ): δ −17.5
(51) Verschoor-Kirss, M. J.; Hendricks, O.; Verschoor, C. M.; Conry,
R.; Kirss, R. U. Inorg. Chim. Acta 2016, 450, 30−38.
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2
6
1
(
br s). 13C{ H} NMR (101 MHz, dmso-d ): δ 67.76 (s, CH of fc),
6
2
3
6
4
8.98 (s, CH of fc), 73.51 (d, J = 15 Hz, CH of fc), 73.86 (d, J
Hz, CH of fc), 75.68 (d, J = 7 Hz, C-P of fc), 96.58 (s, C-SO of
fc), 128.14 (d, JPC = 6 Hz, CH of PPh ), 128.43 (s, CH of PPh ),
=
PC
PC
1
PC
3
2
2
1
1
32.89 (d, JPC = 19 Hz, CH of PPh ), 138.66 (d, J = 11 Hz, Cipso of
2 PC
+
PPh ). HR MS (ESI+): calcd for C H FeO PS ([M + H] ),
51.0215; found, 451.0213. HR MS (ESI−): calcd for C H FeO PS
2
22 20
3
4
(55) Yu, M.; Xie, Y.; Xie, Ch.; Zhang, Y. Org. Lett. 2012, 14, 2164−
2167.
22
18
3
2
−
(
[M − H] ), 449.0069; found, 449.0073.
̌
̌ ̌
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(56) Silverstein, R. M.; Webster, F. X.; Kiemle, D. J. Spectrometric
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2
(
3
(
3
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(
29) Smith, K.; Hou, D. J. Org. Chem. 1996, 61, 1530−1532.
30) Another plausible side product is the anionic phosphine oxide
−
Ph P(O)fcSO3 in the form of salts with various cations.
31) Cation exchangers can promote self-alkylation of alcohols to
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2
(
references therein.
(
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32) Compare these data with the NMR parameters reported for
2
1
[
FcPPh Me]NTf : PMe δ 2.73 ( J = 13.8 Hz), δ 9.5 ( J = 62
2 2 H PH C PC
Hz); δ 22.6. Ku
̈
bler, P.; Sundermeyer, J. Dalton Trans. 2014, 43,
P
3
(
750−3766.
33) Compare also the P−C11/P−C17 bonds: 1.812(2)/1.811(2) Å
in 3, 1.839(2)/1.835(2) Å in 4, and 1.788(2)/1.798(2) Å in 5.
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71. (b) Step
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37) Compound 8 contains a stereogenic sulfur atom but crystallizes
9
(
as a racemate with the symmetry of the centrosymmetric space group
P2 /n.
1
(
(
38) Schultz, T.; Pfaltz, A. Synthesis 2005, 2005, 1005−1011.
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(
(
5
(
3
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L
DOI: 10.1021/acs.organomet.8b00178
Organometallics XXXX, XXX, XXX−XXX