MOP-phosphonites: A novel ligand class for asymmetric catalysis

Article abstract of DOI:10.1039/c2dt12214f

Chiral phosphonite ligands (S,R_b)-5a, (S,S_b)-5b, (R,R_b)-6a and (R,S_b)-6b are introduced, comprising a MOP-type backbone with a binol-based binaphthyl group bound to the phosphorus. Their reaction with [Pd(η³-C₄H₇)Cl] ₂ affords η³-methallylpalladium chloride complexes 7a/b and 8a/b which have been isolated and structurally characterised. Solid-state and solution studies indicate subtle differences in their coordination behaviour, which ultimately affects their efficacy in the asymmetric hydrosilylation of styrene. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2dt12214f

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PAPER
MOP-phosphonites: A novel ligand class for asymmetric catalysis†
Arne Ficks,a Rachel M. Hiney,b Ross W. Harrington,a Declan G. Gilheanyb and Lee J. Higham*a
Received 18th November 2011, Accepted 21st December 2011
DOI: 10.1039/c2dt12214f
Chiral phosphonite ligands (S,Rb)-5a, (S,Sb)-5b, (R,Rb)-6a and (R,Sb)-6b are introduced, comprising a
MOP-type backbone with a binol-based binaphthyl group bound to the phosphorus. Their reaction with
[Pd(η3-C4H7)Cl]2 affords η3-methallylpalladium chloride complexes 7a/b and 8a/b which have been
isolated and structurally characterised. Solid-state and solution studies indicate subtle differences in their
coordination behaviour, which ultimately affects their efficacy in the asymmetric hydrosilylation of
styrene.
phosphiranes with unusually high oxidative and thermal stab-
Introduction
ility.9 We were therefore keen to establish whether we could
Chiral monophosphorus ligands have attracted considerable
attention as their transition metal complexes have been found to
be valuable catalysts in a variety of organic transformations.1
Binaphthyl-derived phosphorus ligands based on phosphine,2
phosphoramidite3 and phosphonite4 architectures (Chart 1) have
all demonstrated their effectiveness in asymmetric catalysis.
Primary phosphines have a reputation for being difficult com-
pounds to work with owing to their perceived high reactivity
towards oxygen.5 Hence, they are somewhat under-represented
as synthons in synthetic chemistry, despite the two P–H bonds
being easily functionalised. A few examples of user-friendly, air-
stable primary phosphines have however been reported,6 and we
were the first to describe enantiopure analogues;7 we sub-
sequently published a DFT-based model to help rationalise this
stability.8 We also recently described how air-stable, chiral
primary phosphines (S)-1 and (R)-2 could form novel
transform (S)-1 and (R)-2 into their dichlorophosphines, and ulti-
mately access MOP/XuPhos-type hybrids (Chart 1), or whether
their resistance to oxidation would render them unreactive to
halogen sources. This work focuses on the synthesis and charac-
terisation of a novel MOP-phosphonite ligand class. The coordi-
nation chemistry of their methallylpalladium complexes is
described and we have therefore investigated their potential as
asymmetric ligands in the catalytic hydrosilylation of styrene.
Results and discussion
Four MOP-phosphonite ligand derivatives have each been syn-
thesised in a straightforward two-step, one-pot reaction approach.
The ligands differ in the substituent on the 2′-position of the
MOP-backbone (H or OMe) and in the stereochemistry of the
affiliated hydroxyl compound ((R)- or (S)-binol). By comparing
the two pairs of diastereomeric compounds with each other, we
were able to elucidate the effect of the second stereocentre.
Following the synthetic method of Weferling,10,11 (S)-1 and
(R)-2 were treated with phosphorus pentachloride to give the
dichlorophosphines (S)-3 and (R)-4 in quantitative conversion.
Subsequent addition of (R)-binol under basic conditions afforded
the MOP-phosphonite hybrids (S,Rb)-5a and (R,Rb)-6a as white
solids (Scheme 1). Their diastereomers (S,Sb)-5b and (R,Sb)-6b
were afforded from reactions with (S)-binol, again in high yield.
The 31P NMR spectroscopic data for the phosphonites are as
expected, showing characteristic resonances (δ = 177.4 ppm for
(S,Rb)-5a; 177.8 ppm for (R,Rb)-6a; 175.7 ppm for (S,Sb)-5b;
177.9 for (R,Sb)-6b). Notably, all the ligands could conveniently
be handled in air; in common reagent grade solvents no hydroly-
sis products were found after 24 h.12 We next studied the coordi-
nation chemistry of the phosphonites; reaction of two
equivalents of the pertinent ligand with [Pd(η3-C4H7)Cl]2
resulted in the rapid, quantitative formation of 7a, 7b, 8a and 8b
(Scheme 2) as shown by NMR, HRMS and X-ray
crystallography.
Chart 1 Established classes of binaphthyl monophosphorus ligands.
aSchool of Chemistry, Bedson Building, Newcastle University, Newcastle
Upon Tyne, NE1 7RU, UK. E-mail: lee.higham@ncl.ac.uk; Tel: (+44)
191 222 5542
bSchool of Chemistry and Chemical Biology, The Centre for Synthesis
and Chemical Biology, University College Dublin, Belfield, Dublin 4,
Ireland
†Electronic supplementary information (ESI) available: Full experimen-
tal and crystallographic data. CCDC reference numbers 840097 (7a),
840098 (7b), 854373 (8a) and 840100 (8b). For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/
c2dt12214f
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and 2.328(1) Å);13 however, shortened Pd–P bond lengths are
anticipated for phosphonite complexes due to their stronger
π-acceptor character.14 Pd–C bond lengths show the dominant
trans effect of the P-ligand relative to the chloride; the bonds
trans to the phosphorus are about 0.1 Å longer compared to the
bonds in the cis position. In all complexes the position of the
palladium centre is face-to-face with the lower naphthyl moiety
of the MOP fragment of the ligand. However, the exact position
of the methallylpalladium moiety is somewhat diverse. When
the phosphonite consists of a (R)-binol fragment (7a/8a), the pal-
ladium is situated towards the back of the lower napthyl ring
(Fig. 1 and Fig. 3); in 7b/8b, as a consequence of the opposite
binol stereochemistry, the metal is instead located above the
front of this group (Fig. 2 and Fig. 4). The distance of the palla-
dium atom from the naphthyl group ranges from 3.0653(1) Å in
7a to 3.4458(1) in 8b.
Scheme 1 The synthesis of phosphonites (S,Rb)-5a and (R,Rb)-6a.
Scheme 2 The synthesis of the complexes 7a, 7b, 8a and 8b.
In all four complexes the X-ray crystal structure reveals the
methyl group on the allyl fragment points towards the binol com-
ponent of the ligand (see Fig. 1–4). The torsion angles of the
two binaphthyl fragments present are significantly different from
each other. The unstrained MOP portion preserves an almost
right angle while the torsion of the binol moiety is enforced by
the bonding of both oxygen atoms to the phosphorus, and thus
appears acutely angled. The ligands coordinate via the phos-
phorus donor atom in an expected monodentate manner to form
a pseudo-square-planar configuration around the palladium. Pd–
P bond lengths are similar in all complexes (2.2354(7) to 2.2542
(8) Å) and are found to be shorter than for the two MOP-phos-
phine allylpalladium complexes previously reported (2.3098(9)
Fig. 2 View of the molecular structure of 7b. Hydrogen atoms have
been omitted for clarity. Selected bond distances (Å) and angles (deg):
Pd–P 2.2354(7), Pd–Cl(1) 2.3730(8), Pd–C(44) 2.078(3), Pd–C(42)
2.198(3), C(42)–C(43) 1.387(4), C(43)–C(44) 1.409(4), Pd⋯C(32)
3.1412(1); P–Pd–Cl(1) 94.51(3), P–Pd–C(44) 96.49(9), Cl(1)–Pd–C(42)
101.71(9), C(42)–Pd–C(44) 67.31(13), C(21)–C(30)–C(31)–C(32)
−90.5(4), C(1)–C(10)–C(11)–C(20) 52.1(4).
Fig. 1 Molecular structure of 7a with 50% probability displacement
ellipsoids. Hydrogen atoms have been omitted for clarity. Selected bond
distances (Å) and angles (deg): Pd–P 2.2476(7), Pd–Cl(1) 2.3854(7),
Pd–C(44) 2.093(2), Pd–C(43) 2.206(2), C(41)–C(43) 1.384(4), C(41)–C
(44) 1.415(4), Pd⋯C(39) 3.0653(1); P–Pd–Cl(1) 93.67(2), P–Pd–C(44)
98.23(9), Cl(1)–Pd–C(43) 101.60(7), C(43)–Pd–C(44) 66.68(11), C
(21)–C(30)–C(31)–C(32) −101.2(3), C(1)–C(10)–C(11)–C(20) −51.2
(3).
Fig. 3 View of the molecular structure of 8a. Hydrogen atoms and
cocrystallised solvent have been omitted for clarity. Selected bond dis-
tances (Å) and angles (deg): Pd–P 2.2363(8), Pd–Cl(1) 2.3755(10), Pd–
C(42) 2.104(4), Pd–C(44) 2.185(4), C(42)–C(43) 1.415(6), C(43)–C(44)
1.381(7), Pd⋯C(32) 3.4018(1); P–Pd–Cl(1) 93.29(3), P–Pd–C(42)
98.24(12), Cl–Pd–C(44) 101.41(16), C(42)–Pd–C(44) 67.08(19), C
(21)–C(30)–C(31)–C(40) −98.0(4), C(1)–C(10)–C(11)–C(20) −52.1(4).
3516 | Dalton Trans., 2012, 41, 3515–3522
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Table 1 Selected 13C NMR data (δ in ppm) for ligands 6a and 6b and
their palladium complexes 8a, 8b, 9a and 9b (CD2Cl2, 21 °C)
Carbon 6a
8aa
9ab
6b
8b
9bb
1′
2′
3′
4′
9′
10′
118.9 118.8 104.6/n.d.c
119.0 118.2 103.4/104.5
156.6 156.4 157.2/159.0 154.9 156.2 156.6/154.8
112.8 113.1 114.9/114.5 113.0 113.5 115.3/115.9
130.8 131.0 134.6/134.6 130.7 129.7 134.9/134.3
134.5 134.2 131.5/131.4 135.0 135.5 132.7/133.7
128.2 127.0 128.4/128.4 128.3 128.2 129.3/130.0
a Major isomer. b Two isomers were observed due to allyl rotation. c No
distinctive assignment due to signal overlap and peak broadening.
and can be ruled out here.18 Note that conversely for complexes
7b and 8b, we observe only a single isomer in each case.
MOP ligands can display unexpected bonding characteristics
upon metal complexation, using their aromatic backbone to co-
ordinate to a vacant metal site, as shown by several groups who
observed binding in a chelating P,C-σ-donor or P,C-π-olefin
bidentate fashion.13b,16,19,20 When the chloride counterions of
complexes 8a and 8b were exchanged for the non-coordinating
BArF anion to give complexes 9a and 9b, the C1′ carbon shifted
by −14.3 (9a) or −15.6/−14.5 ppm (for the two isomers of 9b)
to lower frequency compared to the free ligand, indicative of
greater sp3 character. The chemical shift of the C2′ carbon
remains almost unchanged (Table 1).
In agreement with studies made by Pregosin and co-work-
ers20b we therefore propose a weak η1 binding mode of the lower
naphthyl ring via the C-1′ carbon (Fig. 5, left). The downfield
shifts of 3.8 ppm in 9a and 4.2/3.6 ppm in 9b for the C-4′
carbon also suggests it carries some of the associated positive
charge of the cation, again matching the aforementioned work.
A section of the 13C–1H HMBC spectrum of 9b showing the
indirect resonances of the C1′ and C2′ carbons is given (Fig. 5,
right).
Fig. 4 View of the molecular structure of 8b. Hydrogen atoms and
cocrystallised solvent have been omitted for clarity. Selected bond dis-
tances (Å) and angles (deg): Pd–P 2.2542(8), Pd–Cl 2.3675(7), Pd–C
(43) 2.101(3), Pd–C(42) 2.177(3), C(42)–C(44) 1.402(5), C(43)–C(44)
1.412(4), Pd⋯C(31) 3.4458(1), Pd⋯C(32) 3.4793(0); P–Pd–Cl 98.46
(3), P–Pd–C(43) 96.80(8), Cl–Pd–C(42) 97.23(9), C(42)–Pd–C(43)
67.39(12), C(21)–C(30)–C(31)–C(40) −98.9(3), C(1)–C(10)–C(11)–C
(20) 53.8(4).
The NMR spectra of complexes 7a and 8a show the presence
of two isomers in a 97/3 and 93/7 ratio, respectively, which can
be rationalised by a rotation of the allyl moiety. NOE contacts
between each pair of syn and anti protons and between the syn
allyl protons and the central methyl group, in addition to allyl
proton–phosphorus coupling, allowed for a complete NMR
assignment of the allyl signals (Table S2†). The protons trans to
the phosphorus ligand are deshielded and show coupling with
31P whereas the cis protons are observed as singlets at higher
field.15 The 13C chemical shifts for the atoms in terminal allyl
positions are consistent with those reported for similar com-
plexes:16 77–79 ppm (2JCP ≈ 46 Hz) for the allyl carbons trans
to the P-donor, and 56–59 ppm (2JCP ≈ 5 Hz) for the cis allyl
carbons. The phase-sensitive NOESY spectrum of 8a shows
exchange peaks due to interconversion of the two isomers (see
Fig. S2†). Quantitative analysis of the peak integrals yielded
The catalytic activity of the newly prepared ligands was tested
in the asymmetric hydrosilylation of styrene.21 The catalysts
were generated in situ from allylpalladium chloride dimer and
the appropriate phosphonite. We chose a ligand to palladium
ratio of 1 : 1 to form the catalyst precursors as the methallylpalla-
dium complexes 7a/b and 8a/b had been obtained in this way
(vide supra). We found that the activity of the catalyst was predo-
minantly dependent on the substituent in the 2′-position of the
exchange rate constant values of kAB ≈ 0.12 s−1 and kBA
≈
1.5 s−1 at room temperature.
The selective syn/anti exchange of the allyl protons cis to the
phosphorus is caused by the well-known η3–η1–η3 mechanism
(Scheme 3); the protons in the trans position exchange syn/syn
and anti/anti, while the cis protons exchange syn/anti due to the
selective opening of the allyl ligand.16,17 The selectivity of the
process is due to the stronger trans effect of the P-donor ligand
compared to the chloro ligand. An apparent allyl rotation mech-
anism which is often observed in N-donor ligands requires a syn/
syn and anti/anti exchange for both cis and trans allyl protons
Fig. 5 Left: Proposed binding mode in 9a/b using 13C NMR data.
Right: Section of the 13C–1H HMBC spectrum of 9b with key C1′/H3′
and C2′/H4′ data shown; two isomers of 9b (labelled A, B) are present.
Scheme 3 Syn/anti exchange mechanism in allyl palladium
complexes.
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Table 2 The palladium-catalyzed asymmetric hydrosilylation of
styrene
CH2Cl2 were dried over Na/benzophenone and CaH2 respect-
ively, and distilled prior to use. Toluene (Acros) was purchased
in an anhydrous state and stored over molecular sieves. The prep-
arations of (S)-1 and (R)-2 were carried out using literature pro-
cedures.7 All other chemicals were used as received without
further purification. Flash chromatography was performed on
silica gel from Fluorochem (silica gel, 40–63u, 60A, LC301).
Thin-layer-chromatography was performed on Merck alu-
minium-based plates with silica gel and fluorescent indicator
254 nm. For indicating, UV light or KMnO4 solution (1.0 g
KMnO4, 6.7 g K2CO3, 0.1 g NaOH, 100 mL H2O) was used.
Melting points were determined in open glass capillary tubes on
a Stuart SMP3 melting point apparatus. Optical rotation values
La
Time
Conv.b
eec
1
2
3
4
5a
5b
6a
6b
6 h
4 h
16 h
16 h
94%d
95%d
100%
100%
7% (R)
80% (R)
55% (S)
79% (R)
a The catalyst was generated in situ from the ligand (0.25 mol%) and [Pd
(allyl)Cl]2 (0.125 mol%), and reacted with styrene (10.0 mmol) and
trichlorosilane (12.0 mmol). b Determined by 1H NMR spectroscopy.
c Determined by chiral HPLC; absolute configuration assigned
by comparing the retention times to literature data.23 d Complete
conversion after additional 2 h reaction time.
1
were determined on an Optical Activity Polaar 2001 device. H
NMR, 11B{1H} NMR, 13C{1H} NMR, 19F NMR, and 31P{1H}
NMR spectra were recorded on a JEOL Lambda 500 (1H
500.16 MHz) or JEOL ECS-400 (1H 399.78 MHz) spectrometer
at room temperature (21 °C) if not otherwise stated, using the
indicated solvent as internal reference. Two-dimensional NMR
experiments (COSY, NOESY, HSQC, HMBC) were used for the
assignment of proton and carbon resonances, the numbering
scheme is given in Fig. S1†. Full range NOESY spectra were
acquired with 512 × 1024 data points and a spectral width of
9.0 ppm; mixing times were chosen between 10 and 500 ms. For
the measurement of exchange rate constants in 8a, the proton
resonances of the methoxy group were used. Peak volumes were
determined manually from the NOESY spectrum using Mest-
ReNova 6, and the rate constants were calculated with an esti-
mated error of 10% using EXSYCalc.24 Mass spectrometry was
carried out by the EPSRC National Mass Spectrometry Service
Centre, Swansea. Analytical high performance liquid chromato-
graphy (HPLC) was performed on a Varian Pro Star HPLC
equipped with a variable wavelength detector.
ligand: H-MOP derivatives 5a/b showed a higher activity (>94%
conversion after 6 h) than their corresponding OMe-MOP
derivatives 6a/b (completed after 16 h, Table 2). In contrast, the
selectivity was mostly determined by the configuration of the
adherent binol group. Enantioselectivities of 80 and 79% were
achieved with the (S)-binol derivatives 5b and 6b, while (R)-
binol compounds 5a and 6a gave lower ee values. In previous
studies H-MOP ligands have been found to be more selective in
this transformation than their OMe-MOP counterparts,2a hence
our results for 5a (H-MOP derivative, low ee) and 6b (OMe-
MOP derivative, high ee) were somewhat surprising. Solid-state
analysis of an H-MOP allylpalladium phosphine complex,13b
found to be very selective in the same catalytic reaction,22 shows
a similar P/Pd environment to that found in the H-MOP complex
7b. In contrast, the palladium atom in 7a is located more towards
the back of the lower naphthyl ring. Thus the subtle differences
in the position of the palladium atom relative to the MOP frag-
ment in the catalytically active species could be crucial in deter-
mining the reaction enantioselectivity, again emphasising that we
are comparing pairs of diastereomers in this study; an examin-
ation of the wider implications of these results is now underway.
Synthesis of (S,Rb)-[1,1′-binaphthalene]-2,2′-diyl
[1,1′-binaphthalen]-2-ylphosphonite (5a)
PCl5 (458 mg, 2.20 mmol) was dissolved in toluene (8 mL). (S)-
1 (286 mg, 1.00 mmol) was added and the reaction mixture was
left to stir for 45 min. The volatiles were removed in vacuo to
give (S)-3 (31P{1H} NMR, CDCl3: δ = 157.1 ppm) as a yellow
oil. THF (8 mL), NEt3 (448 mg, 0.64 mL, 4.40 mmol) and (R)-
binol (286 mg, 1.00 mmol) were subsequently added and the
solution was left to stir overnight. The volatiles were removed in
vacuo and the crude product was filtered through a plug of silica
in toluene. The title product was obtained after removal of the
solvent as a white solid. Yield: 404 mg (71%). MP: 158 °C.
[α]2D0 = +238° (c = 1.0 mg mL−1, CHCl3). IR (neat): ν 3055.4,
2981.3, 1588.6, 1505.9, 1462.5, 1362.2, 1326.4, 1228.2, 1203.1,
Conclusions
In summary, we have demonstrated that the air-stable primary
phosphines (S)-1 and (R)-2 readily form their dichlorophosphine
counterparts, which react as electrophiles with enantiopure binol
to give novel chiral phosphonites. We have characterised each
ligand as its methallylpalladium complex by NMR and X-ray
crystallography, which together with detailed NMR experiments
on related cationic complexes indicate the subtly different metal
environment in each case and the P,C ligation of 9a/b. In the
hydrosilylation of styrene, enantioselectivities of 80% were
achieved in reactions that have not yet been optimised.
1154.9, 1070.0, 949.2, 869.5, 818.8, 782.0, 747.7, 629.4 cm−1
.
3
1H NMR (CD2Cl2, 500 MHz): δ (ppm) 8.06 (d, JHH = 8.3 Hz,
3
1H, H4′), 8.01 (d, JHH = 8.3 Hz, 1H, ArH), 7.95–7.91 (m, 3H,
3
3
H14/ArH), 7.88 (d, JHH = 8.2 Hz, 1H, ArH), 7.84 (dd, JHH
=
5
3
Experimental
7.0 Hz, JHP = 1.0 Hz, 1H, H2′), 7.73 (d, JHH = 8.7 Hz, 1H,
3
3
H14′), 7.69 (dd, JHH = 8.3 Hz, JHH = 7.0 Hz, 1H, H3′), 7.61
(d, 3JHH = 8.6 Hz, 1H, H4), 7.56–7.52, (m, 2H, ArH), 7.49–7.40
(m, 4H, H13/ArH), 7.38–7.31 (m, 5H, ArH), 7.30–7.24 (m, 3H,
General
All air- and/or water-sensitive reactions were performed under an
N2 atmosphere using standard Schlenk line techniques. THF and
3
H3/ArH), 6.91 (d, JHH = 8.7 Hz, 1H, H13′). 13C{1H} NMR
3518 | Dalton Trans., 2012, 41, 3515–3522
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2
(CD2Cl2, 126 MHz): δ (ppm) 150.2 (d, JCP = 2.4 Hz, C12),
(87%). MP: >270 °C. [α]2D0 = +444° (c = 1.0 mg mL−1, CHCl3).
IR (neat): ν 2981.2, 1619.8, 1590.0, 1507.0, 1461.8, 1431.0,
1327.7, 1228.2, 1149.5, 1078.1, 947.3, 866.6, 820.5, 799.5,
2
2
149.0 (d, JCP = 6.1 Hz, C12′), 145.0 (d, JCP = 37.2 Hz, C1),
1
136.2 (d, JCP = 38.9 Hz, C2), 135.0, 134.8 (d, JCP = 10.0 Hz),
133.5, 133.3 (d, JCP = 2.1 Hz), 133.0 (d, JCP = 4.7 Hz), 132.9
(d, JCP = 1.5 Hz), 132.8 (d, JCP = 1.0 Hz), 131.7, 131.2, 130.9
(d, JCP = 5.8 Hz, C2′), 130.6 (C14), 129.6 (d, JCP = 0.7 Hz,
C14′), 129.1 (C4′), 128.5, 128.4, 128.3, 128.2, 127.7, 127.1
(C4), 127.0 (d, JCP = 2.8 Hz), 126.8, 126.7, 126.6, 126.6, 126.5,
746.7, 686.7, 630.3 cm−1 1H NMR (CD2Cl2, 500 MHz): δ
.
(ppm) 8.09 (d, 3JHH = 9.1 Hz, 1H, H4′), 7.94–7.90 (m, 4H, H5′/
4
4
3
3
H14/H15′/ArH), 7.89 (d, JHH = 8.2 Hz, 1H, H5), 7.72 (d, JHH
3
= 8.8 Hz, 1H, H14′), 7.59 (d, JHH = 8.5 Hz, 1H, H4), 7.55
(ddd, JHH = 8.2 Hz, JHH = 5.7 Hz, JHH = 2.1 Hz, 1H, H6),
3
3
4
3
3
3
126.3, 126.3, 126.2, 125.0, 124.9 (C3′), 124.9, 124.7 (d, JCP
=
7.53 (d, JHH = 9.1 Hz, 1H, H3′), 7.47 (ddd, JHH = 8.2 Hz,
2
3
4
5.7 Hz, C11), 124.2 (d, JCP = 2.7 Hz, C3), 123.8 (d, JCP = 2.6
Hz, C11′), 122.2 (C13′), 121.5 (d, 3JCP = 1.4 Hz, C13). 31P{1H}
NMR (CD2Cl2, 202 MHz): δ (ppm) 177.4. HRMS (m/z, ESI+,
MeOH): found 585.1605, calcd for [M + H2O]+ 585.1614.
3JHH = 6.8 Hz, JHH = 1.2 Hz, 1H, ArH), 7.44–7.40 (m, 3H,
3
3
4
H13/ArH), 7.38 (ddd, JHH = 8.2 Hz, JHH = 6.8 Hz, JHH = 1.2
Hz, 1H, ArH), 7.36–7.24 (m, 6H, ArH), 7.23 (dd, JHH = 8.5
3
3
3
Hz, JHP = 1.4 Hz, 1H, H3), 7.02 (d, JHH = 8.5 Hz, 1H, ArH),
6.93 (d, 3JHH = 8.8 Hz, 1H, H13′), 3.99 (s, 3H, OCH3). 13C{1H}
4
NMR (CD2Cl2, 126 MHz): δ (ppm) 156.6 (d, JCP = 3.5 Hz,
C2′), 150.3 (d, JCP = 2.5 Hz, C12), 154.9 (d, JCP = 5.8 Hz,
C12′), 141.8 (d, JCP = 37.5 Hz, C1), 136.3 (d, JCP = 37.7 Hz,
C2), 135.3, 134.5 (d, JCP = 2.9 Hz, C9′), 132.9, 132.8, 132.7
2
2
Synthesis of (S,Sb)-[1,1′-binaphthalene]-2,2′-diyl
[1,1′-binaphthalen]-2-ylphosphonite (5b)
2
1
4
The same procedure was followed as for 5a, except for using
(S)-binol as the nucleophile. The title product was obtained as a
white solid after removal of the solvent. Yield: 527 mg (93%).
MP: 197 °C. [α]D20 = −264° (c = 1.0 mg mL−1, CHCl3). IR
(neat): ν 3060.6, 2981.3, 1588.6, 1506.5, 1466.0, 1366.0,
1330.0, 1262.7, 1232.0, 1204.0, 1141.6, 1141.6, 1072.2, 951.6,
(d, JCP = 1.0 Hz), 131.6 (d, JCP = 0.9 Hz), 131.4, 131.2, 130.8
(C4′), 130.5 (C5′), 129.5 (C14′), 128.7, 128.5, 128.5, 128.3
(C5), 128.2 (C10′), 128.1, 127.7, 127.1, 126.8, 126.7 (C4),
126.6, 126.5, 126.4 (d, JCP = 2.6 Hz), 126.2, 126.1, 125.2,
2
124.9, 124.8, 124.5 (d, JCP = 2.0 Hz, C3), 123.8, 122.7 (C13),
3
121.6 (C13′), 118.9 (d, JCP = 10.2 Hz, C1′), 112.8 (C3′), 56.2
869.5, 822.7, 789.4, 753.7, 684.6, 630.2 cm−1
(CD2Cl2, 500 MHz): δ (ppm) 8.04 (d, JHH = 8.2 Hz, 1H, H4′),
.
1H NMR
(s, OCH3). 31P{1H} NMR (CD2Cl2, 202 MHz): δ (ppm) 177.8.
HRMS (m/z, ESI+, CH2Cl2): found 599.1767, calcd for
[M + H]+ 599.1771.
3
3
7.99–7.89 (m, 4H, H14′/ArH), 7.88 (d, JHH = 8.2 Hz, 1H, H5),
7.78 (d, 3JHH = 8.7 Hz, 1H, H14), 7.68 (dd, 3JHH = 8.2 Hz, 3JHH
= 7.0 Hz, 1H, H3′), 7.63 (dd, 3JHH = 7.0 Hz, 5JHP = 1.2 Hz, 1H,
H2′), 7.61 (d, 3JHH = 8.6 Hz, 1H, H4), 7.55 (ddd, 3JHH = 8.2 Hz,
3JHH = 5.5 Hz, JHH = 2.5 Hz, 1H, H6), 7.53–7.36 (m, 7H,
4
Synthesis of (R,Sb)-[1,1′-binaphthalene]-2,2′-diyl
(2′-methoxy-[1,1′-binaphthalen]-2-yl)phosphonite (6b)
H13′/ArH), 7.35–7.28 (m, 3H, H7/H8/ArH), 7.23–7.21 (m, 3H,
H3/ArH), 6.90 (d, JHH = 8.7 Hz, 1H, H13). 13C{1H} NMR
3
The same procedure was followed as for 6a, except for using
(S)-binol as the nucleophile. The title product was obtained as a
white solid after removal of the solvent. Yield: 430 mg (72%).
2
(CD2Cl2, 126 MHz): δ (ppm) 150.1 (d, JCP = 1.9 Hz, C12′),
2
2
148.9 (d, JCP = 5.7 Hz, C12), 145.4 (d, JCP = 37.0 Hz, C1),
136.5 (d, 1JCP = 40.4 Hz, C2), 135.0 (d, JCP = 7.9 Hz), 134.1 (d,
JCP = 2.9 Hz), 133.5, 133.0 (d, JCP = 4.3 Hz), 132.9, 132.8,
131.6, 131.4, 131.2, 130.6 (C14′), 129.6 (C14), 129.4 (C2′),
128.7 (C4′), 128.5, 128.4, 128.4, 128.1 (C5), 127.8, 127.4 (d,
JCP = 2.6 Hz), 127.1 (C4), 127.0, 126.9, 126.8, 126.6, 126.5,
126.4, 126.2, 126.1, 125.9, 125.1 (C3′), 124.9, 124.8 (C11′),
MP: 231 °C (decomposition). [α]2D0 = −310° (c = 1.0 mg mL−1
,
CHCl3). IR (neat): ν 2980.8, 1620.1, 1590.2, 1506.3, 1462.7,
1431.5, 1329.8, 1230.2, 1203.4, 1146.0, 1070.1, 949.5, 867.8,
820.8, 789.7, 747.2, 684.7, 628.8 cm−1
.
1H NMR (CD2Cl2,
3
500 MHz): δ (ppm) 8.09 (d, JHH = 9.1 Hz, 1H, H4′), 7.97 (d,
3JHH = 8.8 Hz, 1H, H14′), 7.93–7.90 (m, 3H, H15/H5′/H15′),
2
124.3 (d, JCP = 2.6 Hz, C3), 123.6 (C11), 122.5 (C13), 121.4
3
3
7.88 (d, JHH = 8.2 Hz, 1H, H5), 7.76 (d, JHH = 8.7 Hz, 1H,
(C13′). 31P{1H} NMR (CD2Cl2, 202 MHz): δ (ppm) 175.7.
HRMS (m/z, EI+): found: = 567.1514, calcd for [M − H]+
567.1508.
H14), 7.60 (d, 3JHH = 8.6 Hz, 1H, H4), 7.54 (dd, 3JHH = 8.0 Hz,
3/4
3
J
HH
= 4.0 Hz, 1H, H6′), 7.52 (d, JHH = 8.8 Hz, 1H, H13′),
3
3
7.51 (d, JHH = 9.1 Hz, 1H, H3′), 7.46 (ddd, JHH = 8.0 Hz,
3JHH = 6.8 Hz, JHH = 1.0 Hz, 1H, H16), 7.42–7.35 (m, 4H,
4
3
H18/ArH), 7.32 (d, JHH = 4.0 Hz, 2H, H7′/H8′), 7.30 (ddd,
Synthesis of (R,Rb)-[1,1′-binaphthalene]-2,2′-diyl
(2′-methoxy-[1,1′-binaphthalen]-2-yl)phosphonite (6a)
3JHH = 8.4 Hz, JHH = 6.8 Hz, JHH = 1.3 Hz, 1H, H17),
3
4
3
7.23–7.18 (m, 4H, H3/ArH), 6.87 (d, JHH = 8.7 Hz, 1H, H13),
PCl5 (458 mg, 2.20 mmol) was dissolved in toluene (8 mL). (R)-
2 (316 mg, 1.00 mmol) was added and the reaction mixture was
left to stir for 45 min. The volatiles were removed in vacuo to
give (R)-4 (31P{1H} NMR, CDCl3: δ = 159.1 ppm) as a yellow
solid. THF (8 mL), NEt3 (448 mg, 0.64 mL, 4.40 mmol) and
(R)-binol (286 mg, 1.00 mmol) were added subsequently and the
solution was left to stir overnight. The volatiles were removed
in vacuo and the crude product was dissolved in toluene and
filtered through a plug of silica. The title product was obtained
after removal of the solvent as a white solid. Yield: 523 mg,
3.89 (s, 3H, OCH3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ
4
2
(ppm) 154.9 (d, JCP = 2.9 Hz, C2′), 150.2 (d, JCP = 2.3 Hz,
C12′), 149.0 (d, JCP = 5.9 Hz, C12), 141.9 (d, JCP = 39.2 Hz,
C1), 136.4 (d, JCP = 38.3 Hz, C2), 135.3, 135.0 (C9′), 132.8,
2
2
1
132.7, 132.7, 131.6, 131.1, 130.7 (C4′), 130.5 (C14′), 129.5
(C14), 128.8, 128.4 (C15), 128.4 (C15′), 128.3 (C5′), 128.3
(C10′), 128.2 (C5), 127.7, 126.9 (C4), 126.8, 126.7, 126.6,
126.5, 126.4 (d, JCP = 2.1 Hz), 126.2, 126.1, 125.5, 124.9,
124.8 (C16), 124.6 (d, JCP = 2.5 Hz), 123.7, 123.6 (d, JCP = 2.5
3
Hz), 122.5 (C13), 121.5 (C13′), 119.0 (d, JCP = 10.3 Hz, C1′),
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 3515–3522 | 3519

View Article Online
3
4
113.0 (C3′), 56.4 (s, OCH3). 31P{1H} NMR (CD2Cl2,
202 MHz): δ (ppm) 177.9. HRMS (m/z, ESI+, CH2Cl2): found
599.1766, calcd for [M + H]+ 599.1771.
Hz, 1H, H13), 4.16 (dd, JHP = 10.2 Hz, JHH = 2.8 Hz, 1H,
3
allyl-Htsyn), 2.56 (d, JHP = 14.8 Hz, 1H, allyl-Htanti), 2.31 (s,
1H, allyl-Hcsyn), 0.93 (s, 3H, allyl-CH3), 0.50 (s, 1H, allyl-
Hcanti). 13C{1H} NMR (CD2Cl2, 126 MHz): δ (ppm) 149.1 (d,
2JCP = 5.3 Hz, C12′), 148.4 (d, JCP = 13.1 Hz, C12), 145.1 (d,
2
Synthesis of [Pd(5a)(η3-C4H7)Cl] (7a)
2JCP = 29.7 Hz, C1), 135.5, 134.5 (d, 1JCP = 9.4 Hz, C2), 134.3,
133.6 (d, JCP = 4.7 Hz), 133.5 d, JCP = 4.4 Hz), 133.3, 132.6 (d,
JCP = 1.4 Hz), 132.1, 131.8 (d, JCP = 0.9 Hz), 131.6, 131.5 (d,
4JCP = 1.0 Hz, C2′), 130.8 (d, JCP = 28.5 Hz, allyl-C), 130.7
[Pd(η3-C4H7)Cl]2 (7 mg, 18 μmol) and 5a (20 mg, 35 μmol)
were dissolved in CH2Cl2 (1 mL) and stirred for 10 min. The
intended complex was formed quantitatively. Slow diffusion of
diethyl ether into the reaction mixture yielded colorless crystals
overnight, which were suitable for X-ray diffraction analysis.
Yield: 25 mg (92%). MP: >270 °C. IR (neat): ν 3052.0, 1587.6,
1505.8, 1460.0, 1432.9, 1360.3, 1322.4, 1220.7, 1067.8, 977.3,
942.2, 871.8, 838.4, 810.2, 759.4, 706.9, 677.2, 634.3,
4
(C14′), 130.2 (d, JCP = 1.4 Hz, C14), 128.6, 128.5, 128.5,
128.3, 128.1, 128.1 (C4′), 127.6 (d, JCP = 4.9 Hz, C4), 127.3,
127.2, 127.1, 127.0, 126.6, 126.6, 126.5, 126.3, 126.3, 126.2
(C3′), 125.5, 125.4, 124.5 (C3), 124.1 (d, JCP = 4.2 Hz, C11′),
3
3
3
3
123.5 (d, JCP = 2.6 Hz, C11), 122.5 (d, JCP = 2.3 Hz, C13′),
121.1 (d, 3JCP = 0.8 Hz, C13), 77.8 (d, 2JCP = 46.5 Hz, allyl-Ct),
1
596.8 cm−1. H NMR (CD2Cl2, 500 MHz): δ (ppm) isomer A
57.6 (d, JCP = 5.3 Hz, allyl-Cc), 22.5 (allyl-CH3). 31P{1H}
2
3
(97%), 7.97 (d, JHH = 8.1 Hz, 1H, H4′), 7.94–7.90 (m, 4H,
NMR (CD2Cl2, 202 MHz): δ (ppm) 172.1. HRMS (m/z, ESI+,
MeOH): found 725.1177, calcd for [M − Cl]+ 725.1176.
H14/H5/H15/H15′), 7.89–7.85 (m, 2H, H2–/H5′), 7.84–7.80 (m,
3
2H, H13/H4), 7.78 (d, 3JHH = 8.9 Hz, 1H, H14′), 7.72 (dd, JHH
= 8.6 Hz, 3JHP = 5.5 Hz, 1H, H3), 7.69 (dd, 3JHH = 8.1 Hz, 3JHH
= 7.2 Hz, 1H, H3′), 7.58–7.55 (m, 1H, ArH), 7.53–7.43 (m, 5H,
H6′/ArH), 7.39–7.27 (m, 5H, ArH), 7.18–7.13 (m, 2H, H13′/
Synthesis of [Pd(6a)(η3-C4H7)Cl] (8a)
3
4
ArH), 3.75 (dd, JHP = 9.9 Hz, JHH = 2.5 Hz, 1H, allyl-Htsyn),
The same procedure was followed as for 7a. Yield: 26 mg
(91%). MP: >270 °C. IR (neat): ν 3065.2, 1620.2, 1589.0,
1507.6, 1463.0, 1431.3, 1327.7, 1247.8, 1223.0, 1194.2, 1151.8,
1068.9, 1021.8, 943.5, 873.9, 839.0, 807.0, 743.7, 677.2, 637.2,
3
2.56 (s, 1H, allyl-Hcsyn), 1.57 (d, JHP = 14.1 Hz, 1H, allyl-
Htanti), 1.00 (s, 3H, allyl-CH3), 0.83 (s, 1H, allyl-Hcanti); isomer
B (3%), 8.00–6.99 (m, 23H, ArH), 6.92 (m, 1H, ArH), 6.87 (m,
3
1H, ArH), 3.96 (d, JHP = 6.8 Hz, 1H, allyl-Htsyn), 2.96 (m, 1H,
597.2, 597.8, 560.2 cm−1
.
1H NMR (CD2Cl2, 500 MHz): δ
3
allyl-Hcsyn), 2.64 (d, JHP = 12.3 Hz, 1H, allyl-Htanti), 1.53 (m,
3
(ppm) isomer A (93%), 7.98 (d, JHH = 9.1 Hz, 1H, H4′), 7.93
1H, allyl-Hcanti), 1.42 (s, 3H, allyl-CH3). 13C{1H} NMR
(dd, 3JHH = 8.9 Hz, 4JHP = 0.9 Hz, 1H, H13), 7.91–7.86 (m, 4H,
2
(CD2Cl2, 126 MHz): δ (ppm) isomer A (97%), 149.1 (d, JCP
=
=
H14/H5/H15/H15′), 7.78–7.73 (m, 2H, H5′/H4), 7.72 (d, 3JHH
=
2
2
5.3 Hz, C12), 148.6 (d, JCP = 13.2 Hz, C12′), 144.7 (d, JCP
3
3
8.9 Hz, 1H, H14′), 7.63 (dd, JHH = 8.6 Hz, JHP = 5.4 Hz, 1H,
27.2 Hz, C1), 135.2, 134.7 (d, 1JCP = 9.3 Hz, C2), 133.5, 133.4,
133.3, 133.1, 132.6 (d, JCP = 1.4 Hz), 132.2 (d, JCP = 1.9 Hz),
131.9 (d, JCP = 1.3 Hz), 131.5 (d, JCP = 1.3 Hz), 131.1 (C2′),
131.0 (d, JCP = 28.6 Hz, allyl-C), 130.7 (d, 4JCP = 1.1 Hz, C14),
130.2 (d, 4JCP = 1.4 Hz, C14′), 129.7, 129.2 (C4′), 128.6, 128.5,
3
3
4
H3), 7.55 (ddd, JHH = 8.1 Hz, JHH = 6.8 Hz, JHH = 1.1 Hz,
1H, ArH), 7.50 (d, 3JHH = 9.1 Hz, 1H, H3′), 7.47–7.24 (m, 10H,
3
4
ArH/H6′), 7.19 (d, JHH = 8.9 Hz, JHP = 1.0 Hz, 1H, H13′),
7.14 (d, 3JHH = 8.4 Hz, 1H, ArH), 3.97 (s, 3H, OCH3), 3.73 (dd,
3JHP = 10.0 Hz, JHH = 3.0 Hz, 1H, allyl-Htsyn), 2.60 (m, 1H,
4
3
128.3, 128.2, 128.2, 127.7 (d, JCP = 5.2 Hz, C4), 127.3, 127.1,
3
allyl-Hcsyn), 1.63 (d, JHP = 14.1 Hz, 1H, allyl-Htanti), 0.92 (s,
3H, allyl-CH3), 0.85 (m, 1H, allyl-Hcanti); isomer B (7%), 8.05
(d, JHH = 9.1 Hz, 1H, H4′), 7.99–7.10 (m, 20H, ArH),
7.07–7.02 (m, 1H, ArH), 6.97 (d, JHH = 8.9 Hz, 1H, H13′),
6.74 (d, JHH = 8.5 Hz, 1H, ArH), 4.12 (s, 3H, OCH3), 3.87 (m,
1H, allyl-Htsyn), 3.18 (m, 1H, allyl-Hcsyn), 1.94 (d, JHP = 13.0
127.1, 127.0 (d, JCP = 2.3 Hz), 126.9, 126.8, 126.7, 126.6,
2
126.4, 125.5, 125.4, 125.2 (C3′), 124.9 (d, JCP = 2.8 Hz, C3),
3
3
3
124.2 (d, JCP = 3.8 Hz, C11), 123.7 (d, JCP = 2.9 Hz, C11′),
122.4 (d, 3JCP = 2.4 Hz, C13), 120.4 (C13′), 76.8 (d, 2JCP = 45.3
Hz, allyl-Ct), 56.1 (d, 2JCP = 5.8 Hz, allyl-Cc), 22.4 (allyl-CH3);
signals of isomer B could not be observed. 31P{1H} NMR
(CD2Cl2, 202 MHz): δ (ppm) isomer A (97%), 173.4; isomer B
(3%), 175.7. HRMS (m/z, ESI+, MeOH): found 727.1178, calcd
for [M − Cl]+ 727.1176.
3
3
3
Hz, 1H, allyl-Htanti), 1.70 (s, 3H, allyl-CH3), 1.35 (m, 1H, allyl-
Hcanti). 13C {1H} NMR (CD2Cl2, 126 MHz): δ (ppm) isomer A
2
(93%), 156.4 (C2′), 149.3 (d, JCP = 5.3 Hz, C12), 149.1 (d,
2JCP = 12.9 Hz, C12′), 141.5 (d, JCP = 27.0 Hz, C1), 135.5 (d,
2
1JCP = 1.4 Hz, C2), 134.2 (C9′), 133.2 (d, JCP = 7.1 Hz), 133.2
(d, JCP = 8.1 Hz), 132.4 (d, JCP = 1.3 Hz), 132.1 (d, JCP = 1.4
Hz), 131.8 (d, JCP = 8.1 Hz), 131.6 (d, JCP = 1.1 Hz), 131.3 (d,
Synthesis of [Pd(5b)(η3-C4H7)Cl] (7b)
4
The same procedure was followed as for 7a. Yield: 23 mg
(83%). MP: >270 °C. IR (neat): ν 3047.7, 1585.8, 1505.6,
1461.1, 1434.2, 1360.9, 1322.9, 1269.3, 1222.1, 1161.0, 1121.5,
1068.7, 1027.5, 977.3, 943.4, 877.1, 839.5, 803.3, 757.5, 729.6,
687.3, 634.8, 598.0, 557.6 cm−1. 1H NMR (CD2Cl2, 500 MHz):
2JCP = 28.8 Hz, allyl-C), 131.0 (C4′), 130.5 (d, JCP = 1.1 Hz,
4
C14), 130.1 (d, JCP = 1.3 Hz, C14′), 128.6, 128.5, 128.4,
128.4, 128.3, 128.2 (C6), 128.0, 127.5 (d, JCP = 5.3 Hz, C4),
127.0 (C10′), 127.0, 126.9 (C5′), 126.7, 126.4, 126.3 (d, JCP
2.3 Hz), 126.2 (C8), 125.4, 125.3, 125.0 (d, JCP = 2.7 Hz, C3),
3
=
2
3
3
3
δ (ppm) 8.13 (d, JHH = 7.0 Hz, 1H, H2′), 7.98–7.86 (m, 7H,
124.5 (C6′), 124.4 (d, JCP = 3.8 Hz, C11), 123.7 (d, JCP = 3.0
Hz, C11′), 122.9 (d, 3JCP = 2.4 Hz, C13), 121.5 (C13′), 118.8 (d,
3
H4′/H15/H5′/H14′/H5/H15′/H13′), 7.83 (d, JHH = 8.8 Hz, 1H,
H14), 7.74 (d, 3JHH = 8.7 Hz, 1H, H4), 7.69 (dd, 3JHH = 8.7 Hz,
3JHH = 7.0 Hz, 1H, H3′), 7.60–7.57 (m, 1H, ArH), 7.53–7.40
3JCP = 9.5 Hz, C1′), 113.1 (C3′), 77.3 (d, JCP = 44.9 Hz, allyl-
2
2
Ct), 56.2 (OCH3), 56.1 (d, JCP = 5.3 Hz, allyl-Cc), 22.5 (allyl-
3
(m, 7H, H3/ArH), 7.36–7.23 (m, 5H, ArH), 7.00 (d, JHH = 8.7
CH3); signals of isomer B could not be observed. 31P{1H} NMR
3520 | Dalton Trans., 2012, 41, 3515–3522
This journal is © The Royal Society of Chemistry 2012

View Article Online
(CD2Cl2, 202 MHz): δ (ppm) isomer A (93%), 173.6; isomer B
(7%) 175.6. HRMS (m/z, ESI+, MeOH): found 755.1301, calcd
for [M − Cl]+ 755.1296.
Hz, 2H, H8), 4.06 (s, OCH3B), 4.00 (s, OCH3A), 3.16 (br d, 3JHP
= 10.7 Hz, allyl-HtantiB), 3.03 (s, allyl-HcsynB), 2.99 (s, allyl-
3
3
HcsynA), 2.90 (d, JHP = 13.2 Hz, allyl-HtantiA), 2.43 (br d, JHP
= 8.2 Hz, allyl-HtsynA), 2.39 (s, allyl-HcantiA), 2.34 (br s, allyl-
HtsynB), 2.22 (s, allyl-HcantiB), 1.58 (s, allyl-CH3A), 1.30 (s,
allyl-CH3B); A : B ratio from integration of CH3 signals: 52 : 48.
11B NMR (CD2Cl2, 160 MHz): δ (ppm) −7.6. 13C{1H} NMR
Synthesis of [Pd(6b)(η3-C4H7)Cl] (8b)
The same procedure was followed as for 7a. Yield: 23 mg
(80%). MP: >270 °C. IR (neat): ν 3066.0, 1619.1, 1587.6,
1506.6, 1463.6, 1429.5, 1323.0, 1276.0, 1226.1, 1199.8, 1155.9,
1117.7, 1070.1, 1028.0, 946.1, 867.4, 833.3, 814.2, 751.9,
(CD2Cl2, 101 MHz): δ (ppm) isomer A,B, 161.8 (q, 1JCB = 40.8
3
Hz, ipso-BArF), 159.0 (C2′B), 157.2 (C2′A), 148.1 (d, JCP
=
10.1 Hz, C11′B), 148.0 (d, JCP = 11.0 Hz, C11′A), 147.1 (d,
3
3JCP = 7.7 Hz, C11), 142.1 (d, JCP = 41.7 Hz, C1B), 141.9 (d,
2
706.2, 686.6, 634.8, 606.6, 560.1 cm−1 1H NMR (CD2Cl2,
.
2JCP = 41.7 Hz, C1A), 137.9 (d, JCP = 9.5 Hz, allyl-CA), 137.0
2
500 MHz): δ (ppm) 8.02 (d, 3JHH = 9.1 Hz, 1H, H4′), 8.00–7.97
(C2), 134.8 (o-BArF), 134.6 (C4′), 132.8, 132.5, 132.1, 132.0,
131.7, 131.6 (C14), 131.5 (C9′A), 131.4 (C9′B), 131.4 (C14′),
130.9, 130.8, 130.4, 130.3 (C4), 130.1 (C5′), 130.0, 129.8,
3
(m, 2H, H15/H13′), 7.94 (d, JHH = 8.9 Hz, 1H, H14′), 7.91 (d,
3JHH = 8.1 Hz, 1H, H5), 7.89 (d, 3JHH = 8.2 Hz, 1H, H15′), 7.86
3
3
(d, JHH = 8.7 Hz, 1H, H14), 7.83 (d, JHH = 8.2 Hz, 1H, H5′),
2
4
129.4, 128.9 (qq, JCF = 31.2 Hz, JCF = 2.8 Hz, m-BArF),
128.8, 128.4 (C10′), 127.5, 127.4, 127.3, 127.1, 127.0, 126.9,
7.65 (d, 3JHH = 8.7 Hz, 1H, H4), 7.59 (ddd, 3JHH = 8.1 Hz, 3JHH
4
= 6.6 Hz, JHH = 1.0 Hz, 1H, H6), 7.54–7.51 (m, 1H, H16),
1
126.5, 126.4, 126.3, 126.0, 125.0, 124.8, 124.7 (q, JCF = 273.2
7.49 (d, 3JHH = 9.1 Hz, 1H, H3′), 7.46–7.39 (m, 3H, ArH/H16′),
7.37–7.27 (m, 7H, ArH/H17/H7′/H6′/H3/H7/H18′), 7.25–7.22
Hz, CF3), 124.1, 124.0 (d, JCP = 3.4 Hz), 123.8, 123.7, 123.3,
122.5, 122.3, 120.7 (C3), 120.6 (C13′), 120.3 (C13), 120.1,
(m, 1H, H17′), 7.00 (d, JHH = 8.7 Hz, 1H, H13), 4.07 (dd, 3JHP
3
3
117.5 (septet, JCF = 4.0 Hz, p-BArF), 114.9 (C3′A), 114.5
4
= 9.9 Hz, JHH = 3.8 Hz, 1H, allyl-Htsyn), 3.87 (s, 3H, OCH3),
2
(C3′B), 104.6 (C1′A), 99.6 (d, JCP = 40.1 Hz, allyl-CtA), 57.5
3
2.35 (s, 1H, allyl-Hcsyn), 2.24 (d, JHP = 13.6 Hz, 1H, allyl-
(OCH3B), 57.4 (OCH3A), 53.2 (allyl-CcA), 22.4 (allyl-CH3A),
21.6 (allyl-CH3B); not all signals could be observed due to peak
broadening and overlap. 19F NMR (CD2Cl2, 471 MHz): δ (ppm)
−62.7. 31P{1H} NMR (CD2Cl2, 202 MHz): δ (ppm) isomer A,
177.5; isomer B, 178.0. HRMS (m/z, ESI+, MeCN): found
757.1287, calcd for [M]+ 757.1281.
Htanti), 0.84 (s, 3H, allyl-CH3), 0.32 (s, 1H, allyl-Hcanti). 13C
{1H} NMR (CD2Cl2, 126 MHz): δ (ppm) 156.2 (C2′), 149.2 (d,
2JCP = 5.3 Hz, C12′), 148.5 (d, JCP = 12.4 Hz, C12), 142.6 (d,
2
2JCP = 29.8 Hz, C1), 135.6 (d, JCP = 1.3 Hz, C2), 135.5 (d,
1
4JCP = 0.9 Hz, C9′), 134.0 (d, JCP = 9.2 Hz), 133.1 (d, JCP = 9.8
Hz), 132.7 (d, JCP = 1.5 Hz), 132.1 (d, JCP = 1.9 Hz), 131.8 (d,
J
CP = 1.3 Hz), 131.6 (d, JCP = 1.3 Hz), 131.3 (d, 2JCP = 26.3 Hz,
allyl-C), 130.5 (d, 4JCP = 0.9 Hz, C14′), 130.1 (d, 4JCP = 1.3 Hz,
C14), 129.7 (C4′), 128.5 (C15), 128.5 (C15′), 128.5 (C6), 128.3
Synthesis of [Pd(6b)(η3-C4H7)]BArF (9b)
3
(C5), 128.2 (C10′), 128.0 (C5′), 127.3 (d, JCP = 4.7 Hz, C4),
The same procedure was followed as for 9a; the intended
product was obtained as a yellow solid. Yield: 54.0 mg (91%).
IR (neat): ν 1612.1, 1588.9, 1506.1, 1463.5, 1353.6, 1273.0,
1219.8, 1116.1, 952.9, 882.4, 836.7, 811.4, 745.5, 711.9, 669.8,
127.0, 127.0, 126.9, 126.8, 126.6, 126.6, 126.2 (C17′), 125.5
2
(C16), 125.3 (C16′), 125.3, 125.1 (d, JCP = 1.4 Hz, C3), 124.1
3
3
(d, JCP = 3.8 Hz, C11′), 123.5, 123.4 (d, JCP = 2.8 Hz, C11),
3
3
123.1 (d, JCP = 2.4 Hz, C13′), 121.4 (C13), 118.2 (d, JCP
=
638.6, 602.7 cm−1 1H NMR (CD2Cl2, 500 MHz): δ (ppm)
.
2
10.5 Hz, C1′), 113.5 (C3′), 79.3 (d, JCP = 46.1 Hz, allyl-Ct),
59.0 (d, 2JCP = 4.5 Hz, allyl-Cc), 56.0 (OCH3), 22.3 (allyl-CH3).
31P {1H} NMR (CD2Cl2, 202 MHz): δ (ppm) 174.4. HRMS
(m/z, ESI+, MeOH): found 755.1280, calcd for [M − Cl]+
755.1296.
3
3
isomer A,B, 8.22 (d, JHH = 9.2 Hz, 1H, H4′A), 8.21 (d, JHH
=
9.2 Hz, 1H, H4′B), 8.17–8.01 (m, 10H, H14/H14′/H5′/ArH),
7.99 (d, JHH = 9.2 Hz, 1H, H3′A), 7.96–7.89 (m, 5H, ArH/H4/
3
H3′B), 7.76 (br s, 16H, o-BArF), 7.64–7.51 (m, 18H, ArH/p-
BArF), 7.49–7.35 (m, 12H, ArH/H13B/H13′A/H13A), 7.30–7.22
(m, 4H, ArH/H7/H13′B), 7.20 (dd, JHH = 8.5 Hz, JHP = 6.9
3
3
Hz, 1H, H3A), 7.10 (dd, JHH = 8.5 Hz, JHP = 6.9 Hz, 1H,
3
3
Synthesis of [Pd(6a)(η3-C4H7)]BArF (9a)
H3B), 6.09 (br d, 1H, H8B), 6.00 (d, JHH = 8.6 Hz, 1H, H8A),
3
3
Sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (33.4 mg,
37.7 μmol) and 8a (30.0 mg, 37.7 μmol) were dissolved in
CH2Cl2 (2 mL) and stirred for 30 min. The reaction mixture was
filtered through a layer of celite and the solvent removed
in vacuo; the intended product was obtained as a yellow solid.
Yield: 48.9 mg (80%). IR (neat): ν 1612.4, 1588.2, 1506.9,
1464.1, 1353.8, 1273.2, 1220.7, 1116.5, 953.5, 882.6, 836.8,
3.98 (s, OCH3A), 3.89 (s, OCH3B), 3.76 (d, JHP = 13.6 Hz,
allyl-HtantiA), 3.00 (br d, allyl-HtsynB), 2.87 (s, allyl-HcsynB),
2.82 (s, allyl-HcsynA), 2.63 (d, JHP = 13.5 Hz, allyl-HtantiB),
3
2.32 (s, allyl-HcantiA), 2.20 (br s, allyl-HcantiB), 2.19 (d, allyl-
HtsynA), 1.79 (br s, allyl-CH3B), 0.96 (s, allyl-CH3A); A : B ratio
of 50 : 50 from integration of OMe resonances (signals of isomer
B broadened). 11B NMR (CD2Cl2, 128 MHz): δ (ppm) −7.6.
813.3, 746.2, 711.9, 681.4, 638.0, 599.2 cm−1
.
1H NMR
13C{1H} NMR (CD2Cl2, 126 MHz): δ (ppm) isomer A,B, 161.8
1
(CD2Cl2, 500 MHz): δ (ppm) isomer A,B, 8.27–7.23 (m, 2H,
H4′B/H4′A), 8.14–7.98 (m, 10H, H5′/H14/H15′/H15/H14′),
7.93–7.89 (m, 3H, H5′/H3′B), 7.86–7.80 (m, 3H, H3′A/H4), 7.74
(br s, 16H, o-BArF), 7.63–7.51 (m, 18H, H6′/H16/H16′/H6/
ArH/p-BArF), 7.48–7.38 (m, 10H, H13/ArH), 7.26–7.19 (m,
(q, JCB = 40.7 Hz, ipso-BArF), 156.6 (C2′A), 154.8 (d, JCP
=
=
2.4 Hz, C2′B), 148.3 (d, 3JCP = 13.5 Hz, C11A), 148.3 (d, 3JCP
13.3 Hz, C11B), 147.2 (d, JCP = 7.1 Hz, C11′A), 147.1 (d, JCP
3
3
= 7.4 Hz, C11′B), 142.4 (d, 2JCP = 43.5 Hz, C1B), 142.2 (d, 2JCP
= 41.3 Hz, C1A), 138.9 (d, JCP = 10.4 Hz, allyl-CA), 138.1 (d,
2
3
4H, H7/ArH), 7.13–7.02 (m, 4H, H13′/H3), 6.06 (d, JHH = 8.3
J = 10.0 Hz, allyl-CB), 137.1 (C2B), 137.0 (C2A), 134.9 (C4′A),
This journal is © The Royal Society of Chemistry 2012
Dalton Trans., 2012, 41, 3515–3522 | 3521

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134.9 (o-BArF), 134.3 (C4′B), 133.7 (C9′B), 132.8, 132.7 (C9′A)
(f) M. T. Reetz, Angew. Chem., Int. Ed., 2008, 47, 2556; (f) J. Ansell and
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4 Y. (A.) Xu, G. C. Clarkson, G. Docherty, C. L. North, G. Woodward and
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3
132.1, 131.8, 131.7, 131.6, 131.5, 130.7 (d, JCP = 4.7 Hz, C4),
130.0 (C10′B), 129.8, 129.8, 129.7, 129.3 (C10′A), 128.9 (qq,
4
2JCF = 31.6 Hz, JCF = 2.9 Hz, m-BArF), 128.7, 128.6, 128.0,
127.6, 127.4, 127.4, 127.0, 127.0, 126.6, 126.5, 126.4, 125.1,
1
124.8, 124.7 (q, JCF = 272.3 Hz, CF3), 124.3, 124.1, 123.7 (d,
2
2JCP = 1.4 Hz, C3B), 123.7 (d, JCP = 1.4 Hz, C3A), 123.0,
5 K. V. Katti, N. Pillarsetty and K. Raghuraman, Top. Curr. Chem., 2003,
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3
3
122.3, 122.1, 120.7 (d, JCP = 1.0 Hz, C13B), 120.6 (d, JCP
=
1.0 Hz, C13A), 120.1 (d, JCP = 2.1 Hz, C13′A), 119.8 (C13′B),
3
6 See for example: (a) M. Brynda, Coord. Chem. Rev., 2005, 249, 2013;
(b) N. Pillarsetty, K. Raghuraman, C. L. Barnes and K. V. Katti, J. Am.
Chem. Soc., 2005, 127, 331; (c) W. Henderson and S. R. Alley, J. Orga-
nomet. Chem., 2002, 656, 120; (d) M. Brynda, M. Geoffroy and
G. Bernardinelli, Chem. Commun., 1999, 961.
7 R. M. Hiney, L. J. Higham, H. Müller-Bunz and D. G. Gilheany, Angew.
Chem., Int. Ed., 2006, 45, 7248.
8 B. Stewart, A. Harriman and L. J. Higham, Organometallics, 2011, 30,
5338.
117.5 (septet, JCF = 4.0 Hz, p-BArF), 115.9 (C3′B), 115.3
3
(C3′A), 104.5 (C1′B), 103.4 (C1′A), 99.5 (d, JCP = 41.1 Hz,
2
allyl-CtA), 96.9 (br, allyl-CtB), 57.6 (OCH3A), 57.3 (OCH3B),
56.4 (allyl-CcB), 54.9 (allyl-CcA), 22.6 (allyl-CH3B), 21.5 (allyl-
CH3A); not all signals could be observed due to peak broadening
and overlap. 19F NMR (CD2Cl2, 471 MHz): δ (ppm) −62.7. 31P
{1H} NMR (CD2Cl2, 202 MHz): δ (ppm) isomer A, 178.9;
isomer B, 179.1. HRMS (m/z, ESI+, MeCN): found 757.1296,
calcd for [M]+ 757.1281.
9 A. Ficks, I. Martinez-Botella, B. Stewart, R. W. Harrington, W. Clegg
and L. J. Higham, Chem. Commun., 2011, 47, 8274.
10 N. Z. Weferling,, Z. Anorg. Allg. Chem., 1987, 548, 55.
11 Note that N-chlorosuccinimide, phosgene, triphosgene and chlorine were
not suitable reagents for the reaction, giving mixtures of compounds:
(a) H. Kischkel and G.-V. Röschenthaler, Chem. Ber., 1985, 118, 4842;
(b) W. A. Henderson Jr., S. A. Buckler, N. E. Day and M. Grayson,
J. Org. Chem., 1961, 26, 4770; (c) L. Dahlenburg and A. Kaunert,
Eur. J. Inorg. Chem., 1998, 885.
12 The presence of trace quantities of HCl and H2O (in unstabilised bench
d-chloroform for instance) did lead to H-phosphinate formation.
13 (a) T. Hayashi, H. Iwamura, M. Naito, Y. Matsumoto, Y. Uozumi,
M. Miki and K. Yanagi, J. Am. Chem. Soc., 1994, 116, 775;
(b) P. G. A. Kumar, P. Dotta, R. Hermatschweiler, P. S. Pregosin,
A. Albinati and S. Rizzato, Organometallics, 2005, 24, 1306.
14 M. C. Bonnet, S. Agbossou and I. Tkatchenko, Acta Cryst, 1987, C43,
445.
15 A. Grabulosa, G. Muller, J. I. Ordinas, A. Mezzetti, M. A. Maestro,
M. Font-Bardia and X. Solans, Organometallics, 2005, 24, 4961.
16 S. Filipuzzi, P. S. Pregosin, M. J. Calhorda and P. J. Costa, Organometal-
lics, 2008, 27, 2949 and references therein.
17 (a) C. Breutel, P. S. Pregosin, R. Salzmann and A. Togni, J. Am. Chem.
Soc., 1994, 116, 4067; (b) B. E. Ketz, A. P. Cole and R. M. Waymouth,
Organometallics, 2004, 23, 2835; (c) H. M. Peng, G. Song, Y. Li and
X. Li, Inorg. Chem., 2008, 47, 8031.
18 (a) A. Guerrero, F. A. Jalon, B. R. Manzano, A. Rodriguez,
R. M. Claramunt, P. Cornago, V. Milata and J. Elguero, Eur. J. Inorg.
Chem., 2004, 549; (b) A. Gogoll, H. Grennberg and A. Axén, Organome-
tallics, 1997, 16, 1167; (c) F. A. Jalón, B. R. Manzano and B. Moreno-
Lara, Eur. J. Inorg. Chem., 2005, 100; (d) V. Montoya, J. Pons, J. Garcia-
Antón, X. Solans, M. Font-Bardía and J. Ros, Organometallics, 2007,
26, 3183; (e) A. Ficks, C. Sibbald, M. John, S. Dechert and F. Meyer,
Organometallics, 2010, 29, 1117.
19 (a) P. Kočovský, Š. Vyskočil, I. Císařová, J. Sejbal, I. Tišlerová,
M. Smrčina, G. C. Lloyd-Jones, S. C. Stephen, C. P. Butts, M. Murray
and V. Langer, J. Am. Chem. Soc., 1999, 121, 7714; (b) P. Dotta,
P. G. A. Kumar, P. S. Pregosin, A. Albinati and S. Rizzato, Organometal-
lics, 2004, 23, 4247; (c) P. Dotta, P. G. A. Kumar, P. S. Pregosin,
A. Albinati and S. Rizzato, Helv. Chim. Acta, 2004, 87, 272; (d) P. Dotta,
P. G. A. Kumar, P. S. Pregosin, A. Albinati and S. Rizzato, Organometal-
lics, 2003, 22, 5345; (e) I. S. Mikhel, H. Rüegger, P. Butti,
F. Camponovo, D. Huber and A. Mezzetti, Organometallics, 2008, 27,
2937.
Asymmetric palladium-catalyzed hydrosilylation of styrene
[Pd(η3-C3H4)Cl]2 (4.6 mg, 0.0125 mmol, 0.125 mol%), ligand
(0.25 mol%) and styrene (1.2 mL, 1.0 g, 10.0 mmol) were
stirred at room temperature for 20 min. Trichlorosilane (1.2 mL,
1.6 g, 12.0 mmol) was added and the reaction was stirred at
room temperature for the appropriate time. The conversion of the
1
reaction was followed by H NMR spectroscopy. The product
was purified by Kugelrohr distillation (reduced pressure,
150 °C).
Trichloro(1-phenylethyl)silane (400 mg, 1.67 mmol) was dis-
solved in MeOH (30 mL) and THF (30 mL). K2CO3 (1.40 g,
10.1 mmol), KF (600 mg, 10.3 mmol) and 35% H2O2 (1.8 mL)
were added subsequently and left to stir overnight. The solution
was filtered, water was added and the product was extracted with
diethyl ether three times. The combined organic washings were
dried over MgSO4 and the crude product was purified by column
chromatography on silica (hexane/ethyl acetate, 4 : 1, Rf = 0.20).
The enantiomeric excess was measured by chiral HPLC
(Column Daicel Chiralcel OD; flow rate: 0.5 mL min−1; hexane/
2-propanol, 95 : 5; retention times: (R) t1 = 19.3 min, (S) t2 =
22.3 min). The absolute configuration was assigned by compar-
ing the retention times to literature data.23
Acknowledgements
We thank the EPSRC for a Career Acceleration Fellowship
(L.J.H.), Studentship (A.F.), an Equipment Grant (R.W.H) and
its National Mass Spectrometry Service Centre, Swansea, UK,
and IRCSET for a Scholarship (R.M.H.).
20 (a) P. S. Pregosin, Chem. Commun., 2008, 4875; (b) P. S. Pregosin,
Coord. Chem. Rev., 2008, 252, 2156.
21 (a) S. E. Gibson and M. Rudd, Adv. Synth. Catal., 2007, 349, 781;
(b) L. Tietze, H. Ila and H. P. Bell, Chem. Rev., 2004, 104, 3453.
22 P. Dotta, P. G. A. Kumar, P. S. Pregosin, A. Albinati and S. Rizzato,
Organometallics, 2004, 23, 2295.
23 M. Ito, Y. Endo, N. Tejima and T. Ikariya, Organometallics, 2010, 29,
2397.
Notes and references
1 Selected review articles: (a) F. Lagasse and H. B. Kagan, Chem. Pharm.
Bull., 2000, 48, 315; (b) I. V. Komarov and A. Börner, Angew. Chem.,
Int. Ed., 2001, 40, 1197; (c) T. Jerphagnon, J.-L. Renaud and C. Bruneau,
Tetrahedron: Asymmetry, 2004, 15, 2101; (d) G. Erre, S. Enthaler,
K. Junge, S. Gladiali and M. Beller, Coord. Chem. Rev., 2008, 252, 471;
24 J. C. Cobas and M. Martín-Pastor, EXSYCalc 1.0; Mestrelab Research,
Escondido, CA, 2007.
3522 | Dalton Trans., 2012, 41, 3515–3522
This journal is © The Royal Society of Chemistry 2012