Synthesis and asymmetric catalytic application of chiral imidazolium-phosphines derived from (1R,2R)-trans-diaminocyclohexane

Article abstract of DOI:10.1016/j.jorganchem.2005.07.110

Reaction between a chiral imidazole-amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P¹Cl (where P¹ = PPh₂, P(1,3,5-Me₃C₆H₃)₂, P(2,2′-O,O′-(1,1′-biphenyl), P((R)

Full text of DOI:10.1016/j.jorganchem.2005.07.110

Journal of Organometallic Chemistry 690 (2005) 5822–5831
www.elsevier.com/locate/jorganchem
Synthesis and asymmetric catalytic application of chiral
imidazolium–phosphines derived from
(1R,2R)-trans-diaminocyclohexane
*
Richard Hodgson, Richard E. Douthwaite
Department of Chemistry, University of York, Heslington, York, YO10 5DD, UK
Received 14 June 2005; accepted 15 July 2005
Available online 19 September 2005
Abstract
Reaction between a chiral imidazole–amine precursor derived from (1R,2R)-trans-diaminocyclohexane and P1Cl (where P1 = PPh2,
P(1,3,5-Me3C6H3)2, P(2,20-O,O0-(1,10-biphenyl), P((R)-(2,20-O,O0-(1,10-binaphthyl))) and P((S)-(2,20-O,O0-(1,10-binaphthyl)))) followed
by RX (where R = nPr, iPr, CHPh2, X = Br; R = iPr, X = I), respectively, gives a selection of chiral imidazolium–phosphine compounds.
Deprotonation of the imidazolium salt gives the corresponding NHC–P ligands that can be used in metal-mediated asymmetric catalytic
applications. Catalytic reactions show that NHC–P ligands give a significantly greater rate of reaction for a palladium catalysed allylic
substitution reaction in comparison to analogous di-NHC or NHC–imine ligands and that NHC–P hybrids are also effective for iridium
catalysed transfer hydrogenation.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Imidazolium salts; N-Heterocyclic carbenes; Catalysis; Allylic substitution; Transfer hydrogenation
1. Introduction
[6,7], however, the development and use of chiral NHC’s
still remains largely underdeveloped.
The application of N-heterocyclic carbene (NHC) li-
gands represents one of the most important developments
in the field of metal-mediated catalysis over recent years
and valuable contributions have been made to a diversity
of reactions [1]. Commonly, NHC’s have been described
as alternatives to tertiary phosphines because of their sim-
ilar electronic properties as ligands, although differences
are apparent, particularly with respect to the much poorer
p-acidity of NHC ligands [2–5]. Furthermore, the distinct
structural differences of NHC compared to phosphines of-
fer the possibility of modified or new reactivity, and the
opportunity of novel structural motifs for asymmetric
chemistry. The potential of chiral NHC for asymmetric
catalytic applications has recently begun to be realised
We have been interested in developing chiral hybrid
NHC ligands principally derived from (1R,2R)-trans-
diaminocyclohexane (Fig. 1) and have prepared new classes
of chiral NHC based ligands, structurally characterised
their metal complexes, and investigated applications to
asymmetric catalysis. However, we have found that the li-
gand classes shown in Fig. 1 generally give slow rates for
reactions that require a formal change in the oxidation
state of the metal [8,9]. As many useful reactions encom-
pass oxidative addition/reductive elimination steps we
wished to prepare new ligands that would increase the rate
of reaction. We assumed that one reason for the slow reac-
tion rates is charge build-up during reductive elimination
that cannot be relieved by the weakly p-acidic NHC or
imine ligand moieties. We therefore instigated a short study
to investigate the synthesis and application of NHC–
phosphine hybrid ligands where it was anticipated that
the phosphine moiety would provide some p-acidity
*
Corresponding author.
E-mail address: red4@york.ac.uk (R.E. Douthwaite).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.07.110

R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
5823
Fig. 1. Chiral diNHC and NHC–imine ligands.
consequently increasing the rate of reaction, and poten-
tially, give a further structural modification inducing good
enantioselectivity.
To date the number of reported NHC–phosphine hy-
brids is limited [10–17], however, chiral derivatives have
been prepared and in two cases excellent eeÕs have been ob-
tained for rhodium [11] and iridium [10] asymmetric hydro-
genation reactions.
2. Results and discussion
2.1. Ligand synthesis
We wished to prepare a small library of chiral imi-
dazolium–phosphine compounds that could serve as pre-
cursors to chelating NHC–P ligands. In previous work,
we described the synthesis of the imidazolium salts 1
and 2 (Scheme 1) that we envisaged would be useful
building blocks to a range of hybrid chiral ligands via
functionalisation of the amine moiety [8,9]. Initial inves-
tigation focused on reactions between 1 or 2 and 1 equiv.
of chlorodiarylphosphines and NEt3; a strategy that has
previously been used with success for the synthesis of
analogous bisphosphines derived from trans-1,2-diamino-
cyclohexane [18,19]. However, we found that reaction
was very solvent dependent and as judged by 31P{1H}
NMR spectroscopy several phosphine containing species
resulted. Unambiguous identification of the target prod-
uct was not possible and separation using recrystallisa-
tion or column chromatography was unsuccessful. We
assumed that the presence or proximity of the imidazo-
lium salt was detrimental to the target reaction and
therefore decided to attempt an alternative strategy
where the phosphine moiety is introduced prior to imi-
dazolium salt formation. Compound 3 shown in Scheme
1 has been described previously [9] and hydrolysis gives
the imidazole–amine 4. Reaction between 4 and 1 equiv.
of Ar2PCl (where Ar = Ph and 1,3,5-Me3C6H3(Mes)) and
NEt3 gives the imidazole–aminophosphines 5 and 6 in
good yield. Characterising data is consistent with the
proposed formulations including a single signal in the
31P{1H} NMR spectrum at d 34.7 and 20.2 ppm for 5
and 6, respectively, that is similar to those observed for
reported Ar2PNR compounds [18].
Scheme 1. (i) ClPAr2, Et3N, C6H6, 25 ꢁC; (ii) HCl(aq); (iii) ClPAr2, Et3N,
C6H6, 25 ꢁC; (iv) RBr, MeCN, 50 ꢁC.
(Scheme 1). In comparison to 5 and 6 the chemical shift
of the 31P{1H} NMR spectra for 7–11 are not significantly
different and in addition to signals attributable to the
1
hydrocarbyl fragment in the H NMR spectrum a signal
at ca. 10 ppm is observed that is characteristic of an
NC(H)N imidazolium proton.
Compounds 7–11 are hygroscopic yellow powders that
in air decompose within minutes as judged by several
new signals in the 31P{1H} NMR spectrum generally con-
sistent with oxidation.
Using similar methodology for 5–11 the imidazole–
phosphoramidates 12–14 were prepared in good yield,
which can then be converted to imidazolium salt deriva-
tives 15–17 as shown in Scheme 2. Phosphoramidates
have been the focus of much attention and used very
successfully in several metal-mediated catalytic reactions
[20–25]. The three phosphite precursors shown in Scheme
2 were chosen partly to investigate the relative influence
of chiral moieties in addition to those derived from 1,2-
trans-diaminocyclohexane. R and S-binaphthol derived
phosphoramidates have been shown to be very effective
ligands for a range of asymmetric catalytic reactions
and coupled with use of an achiral biphenyl derivative,
Imidazolium salt formation is compatible with the phos-
phine functionality and reaction between 5 or 6 and hydro-
n
carbylbromides, RBr (where R = iPr, CHPh2, Pr) gives
the corresponding imidazolium–aminophosphines 7–11

5824
R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
ð1Þ
2.2. Catalysis
We have previously investigated the palladium catalysed
allylic substitution reaction between (E)-1,3-diphenylprop-
3-en-1-yl acetate and dimethylmalonate using chiral di-
NHC and NHC–imine ligands and although in some cases
an excellent enantiomeric excess (ee) could be obtained for
the NHC–imine derivatives (up to 92% ee), the rate of reac-
tion was somewhat disappointing [9]. Typically reactions
required 15 h at 50 ꢁC and the use of NaH as a base. Table
1 shows results of an analogous reaction using ligands 7–11
and 15–17. The data in Table 1 shows that in this unopti-
mised study, using the NHC–phosphine ligands, the rate
of reaction is significantly increased, even at 0 ꢁC (entries
2 and 5), and that a weaker base can be used. The yield
is more sensitive to variation of the phosphine moiety than
the imidazolium N-substituent. Within 5 h yields of A are
essentially quantitative for the ligands 7, 9 and 11 (entries
2, 5 and 7) that contain a PPh2 moiety whereas for ligands
8 and 10 (entries 3 and 6) containing a P(Mes)2 moiety,
reaction is incomplete. Furthermore, comparing entries 2
and 11 at 0 ꢁC, the aminophosphine gives a greater rate
Scheme 2. (i) ClPO2L, Et3N, C6H6, 25 ꢁC, (ii) CH(CH3)2I, 1,4-dioxane,
60 ꢁC.
collectively some insight may be provided into the geo-
metric elements of our ligands that affect catalysis. Fur-
thermore, phosphoramidates are far less prone to
oxidation that aminophosphines and can be handled in
air.
Table 1
Asymmetric allylic substitution between (E)-1,3-diphenylprop-3-en-1-yl
acetate and dimethylmalonatea
Comparison between the NMR data of diastereoisomers
13 and 14 or 16 and 17 indicates that the phosphoramidate
is independent of the imidazole and imidazolium moieties,
respectively. For example the 31P{1H} NMR signals of 13,
14, 16 and 17 are observed at d 149.5, 149.3, 150.0 and
1
150.4 ppm, respectively, and the H NMR signals attrib-
uted to the imidazolium moieties of 16 and 17 are essen-
tially identical.
Entry
Ligand
Temp (ꢁC)
Yield (%)b
ee (%)c
1
2
3
4
5
6
7
8
9
7
7
25
0
25
25
0
25
25
25
25
25
0
98
98
70
98
98
64
98
97
95
86
0
38 (S)
45 (S)
17 (S)
12 (S)
22 (S)
8 (S)
24 (S)
17 (S)
11 (R)
42 (S)
For purposes of catalytic screening we wished to gener-
ate NHC–P ligands in situ and therefore investigated the
deprotonation of representative imidazolium salts 7 and
15 on an NMR tube scale. Reaction between 7 or 15 and
1 equiv. of Na[N(SiMe3)2] in THF-d8 (Eq. (1)) gave quan-
titatively the corresponding NHC compounds 18 and 19,
8
9
9
10
11
15
16
17
17
1
respectively, as judged by H, 13C and 31P NMR spectros-
10
11
a
copy. Characteristic signals attributed to carbene NCN
carbons in the 13C{1H} NMR spectra are observed at d
212.7 and 216.2 ppm and imidazolium NC(H)N proton sig-
2.5 mol% [Pd(n3-C3H5)Cl]2, 5 mol% ligand, (E)-1,3-diphenylprop-3-en-
1-yl acetate, 3.0 equiv. of dimethylmalonate, 2.9 equiv. of BSA, 0.02 equiv.
of KOAc, CH2Cl2, 5 h.
1
nals are absent in H NMR spectra. In the absence of air
b
compounds 18 and 19 are stable indefinitely at room
temperature.
Determined from isolation of pure product by flash chromatography.
Measured by 1H NMR (270 MHz) with (+)-Eu(hfc)3.
c

R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
5825
than a corresponding phosphoramidate 17, although phos-
phoramidates 15 and 16 (entries 8 and 9) give near quanti-
tative yield for A at 25 ꢁC.
presence of the phosphorus atom appears not to be advan-
tageous. Furthermore, it can be seen that in contrast to the
allylic substitution reaction the phosphoramidates give a
greater rate of reaction than the aminophosphines (e.g., en-
try 1 vs. 11). However, in common with the allylic substitu-
tion reaction the P(Mes)2 derivatives 8 and 10 (entries 3
and 7) give poorer yields that the PPh2 derivatives 7, 9
and 11 after the same length of time (entries 1, 5 and 9).
The ee values are again not impressive and in general are
similar to those obtained for the only other study on asym-
metric transfer hydrogenation using NHC ligands [13].
Reactions were analysed after 1 and 5 h to determine if
the ee is dependent on the reaction time as a consequence
of potential racemisation of the product alcohol. Compar-
ison of the 1 and 5 h samples does not indicate that there is
any significant change in the ee as a function of time. In all
reactions R-B is the predominant enantiomer except for li-
gand 16 (entries 13 and 14) that contains a phosphorami-
date moiety derived from R-binaphthol, which favours
S-B. In comparison ligand 17 that incorporates a S-binaph-
thyl moiety does slightly enhance the proportion of R-B
(entries 15 and 16) in comparison to the related achiral
biphenylphosphoramidate 15 (entries 11 and 12), however
overall the enantiomeric ratio is considered quite insensi-
tive to the imidazolium-N and phosphine substituents,
respectively.
However, with respect to the ee values, the ligands in
this study give disappointing results, the highest being ca.
42% S-A for ligands 7 and 17 (entries 2 and 10). The data
corroborate the trend observed in previous work using
NHC–imines where it was found that increasing steric bulk
of the imine substituents significantly reduced the propor-
tion of the S enantiomer. [9] Entry 9 shows that using a
(R)-binaphthol derived phosphoramidate causes a switch
in the preferred stereochemistry of the product from S to
R, however using the analogous (S)-binaphthylphosph-
oramidate does not proportionally increase the quantity
of S product.
Notwithstanding the disappointing eeÕs obtained for the
allylic substitution reaction the significantly improved rates
indicated that investigation into an alternative reaction was
warranted. NHC ligands have previously been investigated
for catalytic hydrogenation using both dihydrogen [26–28]
and transfer hydrogenation methods [29–32], however,
asymmetric examples are rare. Excellent enantioselectivities
have been observed for direct hydrogenation [10,11,33,34]
but transfer hydrogenation has received far less attention,
the only reported example giving a max ee of 53% for
reduction of acetophenone derivatives [13].
Table 2 contains data from iridium catalysed transfer
hydrogenation of acetophenone using ligands 7–11 and
15–17. The rates of reaction are similar to those reported
for other iridium–NHC catalysts and in this context the
3. Conclusions
We have shown that NHC–P ligands are effective as ancil-
lary ligands for an allylic substitution and a transfer hydro-
genation reaction. Comparison with previous work
indicates that the presence of the phosphine moiety increases
the rate of the allylic substitution reaction with respect to re-
lated di-NHC and NHC–imine ligands. A possible reason
for the increase in rate is the potential for the phosphine do-
nor to act as a p-acid relieving charge build-up at the palla-
dium atom. Other mechanisms to relieve charge build-up,
such as widening of the CNHC–Pd–P angle or dissociation
of an ancillarly ligand donor to give a 3-coordinate complex,
are restricted by the constrained geometry of the palladacy-
cle and because the ligand is chelating. Although the eeÕs re-
ported for the two reactions investigated are to say the least
modest, successful elaboration of the imidazole–amine 4 al-
lows a wider array of ligands to be prepared than previously
available from the corresponding imidazolium–amines. It is
therefore envisaged that a more diverse library of chiral
NHC-based ancillary ligands will therefore become avail-
able for screening studies.
Table 2
Asymmetric transfer hydrogenation of benzophenone in isopropanola
Entry
Ligand
Time (h)
Conversion (%)b
ee (%)b
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
a
7
7
1
5
1
5
1
5
1
5
1
5
1
5
1
5
1
5
70
93
46
74
68
89
44
68
72
90
84
95
87
94
86
96
18 (R)
15 (R)
15 (R)
13 (R)
34 (R)
31 (R)
21 (R)
21 (R)
16 (R)
11 (R)
15 (R)
12 (R)
26 (S)
20 (S)
37 (R)
34 (R)
8
8
9
9
10
10
11
11
15
15
16
16
17
17
4. Experimental
4.1. General procedures
0.25 mol% [Ir(COD)Cl]2, 0.5 mol% ligand, 2.5 mol% KOH, acetoph-
All manipulations were performed under argon using
standard Schlenk techniques unless stated otherwise. All
enone, (CH3)2CHOH, 80 ꢁC.
b
Determined by GC.

5826
R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
solvents were distilled under dinitrogen from a drying
agent prior to use: calcium hydride (dichloromethane and
acetonitrile), sodium benzophenone ketyl (diether ether,
petroleum ether (40–60 ꢁC) and tetrahydrofuran), or so-
dium (benzene). Reagents were purchased from Aldrich,
Acros or Lancaster and used as supplied, except triethyl-
moval of the volatiles under reduced pressure gave 4 as a
yellow solid. Yield: 0.33 g, 92%. MS (CI+): m/z 242
(100%) [M + H]+. MS (HRCI+): Calc. for C15H20N3:
242.1657. Found: 242.1662. 1H NMR (chloroform-d1,
270 MHz) 1.02–1.88 (8H, m, c-hexCH2), 2.02 (2H, m,
NH2), 3.04 (1H, m, c-hexCHNamine), 3.69 (1H, m, c-hexCH-
N
), 7.06 (1H, s, imidNCHC), 7.42 (5H, m, PhCH), 7.69
imid
amine,
chlorodiphenylphosphine,
1-bromopropane,
2-bromopropane, 2-iodopropane and bromodiphenyl-
methane. Triethylamine was dried over calcium hydride
and distilled under argon. Chlorodiphenylphosphine was
distilled under reduced pressure. 1-Bromopropane,
2-bromopropane and 2-iodopropane were dried over MgSO4
and fractionally distilled under argon. Bromodiphenylphos-
phine was sublimed under reduced pressure. Compounds
1–3 [9], chlorodimesitylphosphine, chlorobiphenylphosphite,
and (R) and (S)-chlorobinaphthylphosphite, were prepared
using literature procedures [35,36] NMR spectra were re-
(1H, s, imidNCHN). 13C{1H} NMR (chloroform-d1,
67.9 MHz) 24.6, 25.4, 34.1, 34.6 (c-hexCH2), 55.9 (c-hexCH-
amine
N
), 61.9 (c-hexCHNimid), 127.6 (NCHC), 128.0, 128.7,
129.4 (PhCH), 130.0 (imidC(Ph)N), 133.9 (PhCipso), 134.7
(NCHN).
4.3. Synthesis of C(H)N(H)PPh2 (5)
To a stirred solution of 4 (72 mg, 0.30 mmol) in benzene
(3 mL) at 25 ꢁC was added triethylamine (42 lL, 0.30
mmol) and chlorodiphenylphosphine (54 lL, 0.30 mmol).
The resulting solution was stirred for 2 h to give a white
precipitate. The mixture was filtered and the volatiles re-
moved from the filtrate under reduced pressure to give 5
as a pale yellow solid. Yield: 109 mg, 85%. MS (FAB+):
m/z 426 (61%) [M + H]+, 442 (100%) [M + H + O]+. MS
(HRFAB+): Calc. for C27H29N3P: 426.2099. Found:
426.2102. 1H NMR (benzene-d6, 270 MHz) d 0.82 (3H,
m, c-hexCH2), 1.30 (3H, m, c-hexCH2), 1.62 (1H, m, NH),
1.83 (2H, m, c-hexCH2), 3.06 (1H, m, c-hexCHNphos), 3.69
(1H, m, c-hexCHNimid), 6.95–7.32 (15H, m, PhCH), 7.36
(1H, s, imidNCHC), 7.76 (1H, s, imidNCHN). 13C{1H}
NMR (benzene-d6, 67.9 MHz) d 25.1, 25.4, 35.1 (c-hexCH2),
corded at probe temperature on a Bruker AMX-300 (1H,
¨
300 MHz; 13C, 75.5 MHz; 31P, 121.5 MHz), Bruker AV-
¨
500 (1H, 500 MHz; 13C, 125 MHz; 31P, 202.4 MHz), Jeol
EX 270 (1H, 270 MHz; 13C, 67.9 MHz; 31P, 109.4 MHz),
or a Jeol ECX 400 (1H, 400 MHz; 13C, 100.5 MHz; 31P,
161.8 MHz), respectively. Chemical shifts are described in
parts per million downfield shift from SiMe4 and are re-
ported consecutively as position (dH, dC or dP), relative
integral, multiplicity (s = singlet, d = doublet, t = triplet,
q = quartet, sext = sextet, sep = septet, m = multiplet,
dd = doublet of doublet, br = broad, v = virtual), coupling
constant (J/Hz) and assignment. Proton NMR spectra
were referenced to the chemical shift of residual proton sig-
nals (CHCl3 d 7.27, C6D5H d 7.16, CDHCl2 d 5.3, C4D7HO
d 3.58 and CD2HCN d 1.94). Carbon spectra were refer-
enced to a 13C resonance of the solvent (CDCl3 d77.16,
C6D6 d 128.06, CD2Cl2 d 54.0, C4D8O d 67.6 and CD3CN
d 118.26). 13C HSQC, PENDANT and Gradient HMBC
3
3
36.8 (d, JP–C = 4.8, c-hexCH2), 60.8 (d, JP–C = 4.8,
c-hexCHNimid), 61.8 (d, JP–C = 27.7,
CHNphos), 127.4
2
c-hex
(NCHC), 127.9, 128.1, 128.4, 128.6, 128.9 (PhCH), 128.8
2
(
imidC(Ph)N), 129.8 (PhCH), 131.0 (d, JP–C = 20.8,
PPhCH), 131.5 (PhCH), 131.6 (d, JP–C = 20.8, PPhCH),
2
1
experiments were performed using standard Bruker pulse
¨
133.7 (PhCipso), 135.9 (br, NCHN), 143.3 (d, JP–C = 57.5,
PPh
1
PPh
sequences. Chemical ionisation (CI+), and Fast Atom
Bombardmant (FAB+) mass spectra were recorded on a
Micromass Autospec spectrometer, using 3-nitrobenzyl
alcohol as the matrix. Electrospray (ES) mass spectra were
recorded on a Micromass LCT using dichloromethane as
the mobile phase. Major fragments were given as percent-
ages of the base peak intensity (100%). Elemental Analyses
were performed at the University of Manchester.
C
ipso
), 143.9 (d, JP–C = 63.1,
C
). 31P{1H} NMR
ipso
(benzene-d6, 109.4 MHz) d 34.7 (s, NPPh2).
4.4. Synthesis of C(H)N(H)PMes2 (6)
To a stirred solution of 4 (72 mg, 0.30 mmol) in benzene
(3 mL) at 25 ꢁC was added triethylamine (42 lL, 0.30
mmol) and chlorodimesitylphosphine (91 mg, 0.30 mmol).
The resulting solution was stirred for 5 h to give a
white precipitate. Workup as for 5 gives 6 as a pale
yellow solid. Yield: 136 mg, 89%. MS (FAB+): m/z 510
(76%) [M + H]+, 526 (100%) [M + H + O]+. MS
(HRFAB+): Calc. for C33H41N3P: 510.3038. Found:
510.3048. 1H NMR (benzene-d6, 270 MHz) d 0.61–2.62
(8H, m, c-hexCH2), 1.26 (1H, m, NH), 2.07 (3H, s,
p-MesCH3), 2.10 (3H, s, o-MesH3), 2.27 (6H, s, o-MesCH3),
2.30 (6H, s, o-MesCH3), 3.07 (1H, m, c-hexCHNphos), 3.70
(1H, m, c-hexCHNimid), 6.52–6.72 (4H, m, m-MesCH), 7.00–
7.14 (5H, m, PhCH), 7.24 (1H, s, imidNCHC), 7.50 (1H, s,
4.2. Synthesis of 1R-amino-2R-(5-phenylimidazolyl)-
cyclohexane (C(H)NH2) (4)
A mixture of 1R-(benzylidene-amino)-2R-(5-phenylimi-
dazolyl)-cyclohexane, 3 (0.5 g, 1.5 mmol) and hydrochloric
acid (10 mL, 1 M) was stirred at 25 ꢁC for 2 h, filtered and
the filtrate washed with CH2Cl2 (2 · 10 mL). The aqueous
solution was cooled to 5 ꢁC and an aqueous solution of so-
dium hydroxide (12 mL, 1 M) added drop wise to pH 9–11.
The resulting cloudy precipitate was extracted with diethyl
ether (2 · 10 mL) and the combined ether layers washed
with water (10 mL), dried over MgSO4 and filtered. Re-
imidNCHN). 13C{1H} NMR (benzene-d6, 67.9 MHz) d
3
22.3
(
MesCH3), 22.5 (d, JP–C = 4.1, MesCH3), 22.8

R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
5827
3
(
(
MesCH3), 23.1 (d, JP–C = 4.1, MesCH3), 24.6, 25.5
13C{1H} NMR (acetonitrile-d3, 75.5 MHz) d 21.9, 22.5
c-hexCH2), 33.8 (d, JP–C = 5.5, c-hexCH2), 34.4 (c-hexCH2),
(
MesCH3), 22.8 (d, JP–C = 4.4, MesCH3), 23.1 (d,
3
3
60.6 (d, 2JP–C = 25.9, c-hexCHNphos), 61.1 (br, c-hexCHNimid),
127.8 (NCHC), 128.7, 129.8, 130.1, 130.4, 130.6
3JP–C = 4.4, MesCH3), 23.2, 23.4 (c-hexCH2), 25.9, 26.0
3
(CH3), 35.2 (d, JP–C = 5.27, c-hexCH2), 36.1 (c-hexCH2),
(
aromaticCH), 131.0 (imidC(Ph)N), 133.8 (PhCipso), 135.2 (br,
55.0 (CH(CH3)2), 62.0 (d, 2JP–C = 28.2, c-hexCHNphos), 65.6
Mes
3
NCHN), 136.6
(
C
), 136.7 (d, 2JP–C = 24.9,
(d, JP–C = 5.9, c-hexCHNimid), 120.2 (NCHC), 126.4
ipso
Mes
2
Mes
C
), 137.6 (d, JP–C = 23.8,
C
), 136.9 (MesCipso),
(
imidC(Ph)N), 129.3, 129.7, 129.8, 130.1, 131.3 (aromaticCH),
ipso
ipso
1
PMes
1
2
140.4 (d, JP–C = 43.5,
C
ipso
), 140.7 (d, JP–C = 44.6,
134.5 (br, NCHN), 135.1 (PhCipso), 137.0 (d, JP–C = 23.6,
PMes
Mes
2
Mes
C
ipso
). 31P{1H} NMR (benzene-d6, 121.50 MHz) d
C
C
), 137.3 (d, JP–C = 23.8,
C
), 137.7, 138.0
ipso
ipso
PMes
Mes
1
20.2 (s, NPMes2).
(
), 141.8.0 (d, JP–C = 48.7,
C
ipso
), 142.5 (d,
ipso
1JP–C = 50.0,
C
). 31P{1H} NMR (acetonitrile-d3,
PMes
ipso
4.5. Synthesis of [iPrC(H)N(H)PPh2][Br] (7)
121.5 MHz) d 23.4 (s, NPMes2). Anal. Calc. for
C36H47N3BrP: C, 68.34; H, 7.49; N, 6.64. Found: C, 68.53;
H, 7.61; N, 6.47%.
In an ampoule sealed with a Teflon stopcock an acetoni-
trile solution (3 mL) of 5 (85 mg, 0.20 mmol) and 2-bromo-
propane (20 lL, 0.21 mmol) was stirred at 50 ꢁC for 72 h.
The solution was reduced in volume to ca. 0.5 mL under
reduced pressure and added dropwise to benzene (10 mL)
to give an off white precipitate that was filtered, washed with
benzene (2 · 5 mL) and dried under reduced pressure to give
7 as a pale yellow solid. Yield: 90 mg, 82%. MS (FAB+): m/z
468 (100%) [M ꢀ Br]+. MS (HRFAB+): Calc. for
C30H35N3P: 468.2569. Found: 468.2580. 1H NMR (acetoni-
trile-d3, 300 MHz) d 1.12–2.21 (8H, m, c-hexCH2), 1.53 (3H,
4.7. Synthesis of [CH(Ph)2C(H)N(H)PPh2][Br] (9)
In an ampoule sealed with a Teflon stopcock an acetoni-
trile solution (3 mL) of 5 (85 mg, 0.20 mmol) and bro-
modiphenylmethane (52 mg, 0.21 mmol) was stirred at
50 ꢁC for 72 h. Workup as for 7 gives 9 as a yellow solid.
Yield: 106 mg, 79%. MS (FAB+): m/z 592 (100%)
[M ꢀ Br]+. MS (HRFAB+): Calc. for C40H39N3P:
592.2882. Found: 592.2874. 1H NMR (acetonitrile-d3,
300 MHz) d 0.95–2.28 (8H, m, c-hexCH2), 3.37 (1H, m,
NH), 3.59 (1H, m, c-hexCHNphos), 4.14 (1H, m, c-hexCHNi-
mid), 6.72–7.87 (25H, m, PhCH), 6.97 (1H, s, CH(C6H5)2),
7.64 (1H, s, imidNCHC), 9.97 (1H, s, imidNCHN).
13C{1H} NMR (acetonitrile-d3, 75.5 MHz) d 23.0, 23.3,
3
3
d, JH–H = 6.7, CH(CH3)2), 1.54 (3H, d, JH–H = 6.7,
CH3), 3.31 (1H, m, NH), 3.80 (1H, m, c-hexCHNphos), 4.10
3
(1H, m, c-hexCHNimid), 4.65 (1H, vsep, JH–H = 6.7,
CH(CH3)2), 7.09–7.58 (15H, m, PhCH), 7.46 (1H, s,
imidNCHC), 10.06 (1H, s, imidNCHN). 13C{1H} NMR (ace-
tonitrile-d3, 75.5 MHz) d 22.9, 23.1 (c-hexCH2), 25.5, 25.6
(CH3), 34.7 (c-hexCH2), 36.9 (d, 3JP–C = 4.1, c-hexCH2), 54.2
3
34.9 (c-hexCH2), 37.1 (d, JP–C = 4.1, c-hexCH2), 61.7
2
(CHPh2), 63.1 (d, JP–C = 28.5, c-hexCHNphos), 65.2 (d,
(CH(CH3)2), 61.5 (d, JP–C = 29.8, c-hexCHNphos), 64.9 (d,
3JP–C = 6.0, c-hexCHNimid), 117.3 (NCHC), 125.9
2
3JP–C = 6.2, c-hexCHNimid), 118.7 (NCHC), 126.6
(
imidC(Ph)N), 127.6, 127.7, 128.6, 128.9, 129.0, 129.1,
(
imidC(Ph)N), 129.0, 129.1, 129.3, 129.5, 129.9, 130.0 (PhCH),
129.3, 129.5, 130.1, 130.5, 130.7, 130.8, 131.0 (PhCH),
2
2
2
130.9 (d, JP–C = 24.9, PhCH), 131.0 (PhCH), 131.2 (d,
2JP–C = 24.2, PhCH), 135.7 (br, NCHN), 136.4 (PhCipso),
131.2 (d, JP–C = 24.8, PhCH), 131.4 (d, JP–C = 24.5,
PhCH), 135.6 (PhCipso), 135.9 (br, NCHN), 136.3, 136.9
1
PPh
1
1
PPh
1
144.0 (d, JP–C = 64.5,
C
ipso
), 144.2 (d, JP–C = 71.4,
(PhCipso), 144.4 (d, JP–C = 59.8,
C
), 144.6 (d, JP–C
ipso
PPh
PPh
C
). 31P{1H} NMR (acetonitrile-d3, 121.5 MHz) d
=68.4,
C
ipso
). 31P{1H} NMR (acetonitrile-d3,
d 37.9 (s, NPPh2). Anal. Calc. for
ipso
37.7 (s, NPPh2). Anal. Calc. for; C30H35N3BrP; C, 65.69;
121.5 MHz)
H, 6.43; N, 7.66. Found: C, 65.41; H, 6.30; N, 7.56%.
C40H39N3BrP: C, 71.42; H, 5.84; N, 6.25. Found: C,
71.63; H, 5.79; N, 6.37%.
4.6. Synthesis of [iPrC(H)N(H)PMes2][Br] (8)
4.8. Synthesis of [CH(Ph)2C(H)N(H)PMes2] [Br] (10)
In an ampoule sealed with a Teflon stopcock a mixture of
acetonitrile (3 mL), 6 (102 mg, 0.20 mmol) and 2-bromopro-
pane (20 lL, 0.21 mmol) was stirred at 50 ꢁC for 72 h. Work-
up as for 7 gives 8 as a pale yellow solid. Yield: 95 mg, 75%.
MS (FAB+): m/z 552 (100%) [M ꢀ Br]+. MS (HRFAB+):
Calc. for C36H47N3P: 552.3508. Found: 552.3519. 1H
NMR (acetonitrile-d3, 300 MHz) d 0.98–2.58 (8H, m,
c-hexCH2), 1.57 (3 H, d, 3JH–H = 6.6, CH(CH3)2), 1.58 (3 H,
In an ampoule sealed with a Teflon stopcock a mixture of
acetonitrile (3 mL),
6 (85 mg, 0.20 mmol) and bro-
modiphenylmethane (52 mg, 0.21 mmol) was stirred at
50 ꢁC for 72 h. Workup as for 7 gives 10 as a yellow solid.
Yield: 109 mg, 72%. MS (FAB+): m/z 676 (100%)
[M ꢀ Br]+. MS (HRFAB+): Calc. for C46H51N3P:
676.3821. Found: 676.3824. 1H NMR (acetonitrile-d3,
300 MHz) d 0.92–2.63 (8H, m, c-hexCH2), 2.20 (3H, s,
o-MesH3), 2.23 (3H, s, o-MesH3), 2.46 (6H, s, o-MesCH3), 2.48
(6H, s, o-MesCH3), 3.10 (1H, m, NH), 3.67 (1H, m, c-hexCHNphos),
4.05 (1H, m, c-hexCHNimid), 6.68–7.78 (19H, m, PhCH), 6.91
(1H, s, CH(C6H5)2), 7.35 (1H, s, imidNCHC), 10.09 (1H, s,
imidNCHN). 13C{1H} NMR (acetonitrile-d3, 75.5 MHz) d
3
d, JH–H = 6.6, CH3), 2.13 (3 H, s, o-MesH3), 2.15 (3H, s,
o-MesH3), 2.32 (6H, s, o-MesCH3), 2.35 (6H, s, o-MesCH3),
3.36 (1H, m, NH), 3.76 (1H, m, c-hexCHNphos), 4.09 (1H,
m, c-hexCHNimid), 4.68 (1H, vsep, 3JH–H = 6.6, CH(CH3)2),
6.56–6.82 (4H, m, m-MesCH), 7.11–7.30 (5H, m, PhCH),
7.39 (1H, s, imidNCHC), 10.14 (1H, s, imidNCHN).

5828
R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
21.1, 21.6 (MesCH3), 22.0 (d, 3JP–C = 4.3, MesCH3), 22.5 (d,
3JP–C = 4.2, MesCH3), 22.9, 23.1 (c-hexCH2), 34.9 (d,
3JP–C = 4.9, c-hexCH2), 35.7 (c-hexCH2), 61.3 (CHPh2), 63.8
13C{1H} NMR (benzene-d6, 67.9 MHz) d 25.0, 25.2, 34.5
3
2
(
c-hexCH2), 36.1 (d, JP–C = 4.1, c-hexCH2), 55.4 (d, JP–C
=
25.9, c-hexCHNphos), 60.7 (br, c-hexCHNimid), 122.6, 122.8,
124.7, 125.0 (BiPhCH), 127.9 (NCHC), 128.6, 128.8, 129.0,
2
3
(d, JP–C = 26.1, c-hexCHNphos), 66.0 (d, JP–C = 5.0,
c-hexCHNimid), 119.5 (NCHC), 125.1 (imidC(Ph)N), 128.7,
128.9, 129.0, 129.3, 129.4, 129.7, 129.8, 130.1, 131.3, 131.4,
131.6 (aromaticCH), 134.5 (br, NCHN), 135.8, 136.5
129.5.1, 129.7, 129.9, 130.1
(
aromaticCH), 131.7
3
BiPh
(
imidC(Ph)N), 132.1 (d, JP–C = 3.12,
C
), 132.2 (d,
ipso
BiPh
3JP–C = 3.24,
C
), 133.9 (PhCipso), 135.9 (NCHN),
ipso
aromatic
2
aromatic
2
O2BiPh
2
(
C
), 137.1 (d, JP–C = 24.67,
C
), 137.5
150.4 (d, JP–C = 5.1,
C
), 150.9 (d, JP–C = 4.1,
ipso
ipso
ipso
(d, 2JP–C = 24.3, aromaticCipso), 137.7 (aromaticCipso), 141.8 (d,
C
ipso
). 31P{1H} NMR (benzene-d6, 109.4 MHz) d
O2BiPh
1JP–C = 45.5,
C
), 142.5 (d, JP–C = 48.3,
ipso
C
ipso
).
148.9 (s, NPO2BiPh).
PMes
1
PMes
31P{1H} NMR (acetonitrile-d3, 121.5 MHz) d 23.6 (s,
NPMes2). Anal. Calc. for C30H33N3BrP: C, 73.00; H, 6.79;
N, 5.55. Found: C, 73.15; H, 6.91; N, 5.50%.
4.11. Synthesis of C(H)N(H)PO2Binap(R) (13)
To a stirred solution of 4 (48 mg, 0.20 mmol) in benzene
(2 mL) at 25 ꢁC was added triethylamine (28 lL,
0.20 mmol) and (R)-chlorobinaphthylphosphite (70 mg,
0.20 mmol). Workup as for 12 gives 13 as a yellow solid.
Yield: 86 mg, 77%. MS (FAB+): m/z 556 (100%)
[M + H]+. MS (HRFAB+): Calc. for C35H31N3O2P:
556.2154. Found: 556.2168. 1H NMR (benzene-d6,
270 MHz) d 0.36 (1H, m, c-hexCH2), 0.71 (1H, m, c-hexCH2),
0.89 (1H, m, c-hexCH2), 1.27 (3H, m, c-hexCH2), 1.66 (1H, m,
c-hexCH2), 1.78 (1H, m, c-hexCH2), 2.75 (1H, m, NH), 3.02
(1H, m, c-hexCHNphos), 3.40 (1H, m, c-hexCHNimid), 6.90–
7.71 (17H, m, aromaticCH), 7.33 (1H, s, imidNCHC), 7.67
4.9. Synthesis of [nPrC(H)N(H)PPh2][Br] (11)
In an ampoule sealed with a Teflon stopcock an acetoni-
trile solution (3 mL) of 5 (85 mg, 0.20 mmol) and 1-bromo-
propane (20 lL, 0.21 mmol) was stirred at 50 ꢁC for 72 h.
Workup as for 7 gives 11 as a pale yellow solid. Yield:
92 mg, 84%. MS (FAB+): m/z 468 (100%) [M ꢀ Br]+.
MS (HRFAB+): Calc. for C30H35N3P: 468.2569. Found:
468.2566. 1H NMR (acetonitrile-d3, 270 MHz) d 0.94
3
(3H, t, JH–H = 7.3, CH2CH3), 1.14–2.33 (8H, m,
3
c-hexCH2), 1.90 (2H, sex, JH–H = 7.3, CH2CH3), 3.27
(1H, m, NH), 3.67 (1H, m, c-hexCHNphos), 4.10 (1H, m,
(1H, s, imidNCHN). 13C{1H} NMR (benzene-d6,
3
3
c-hexCHNimid), 4.13 (2H, t, JH–H = 7.3, NCH2CH2),
75.5 MHz) d 25.1, 25.2, 34.4 (c-hexCH2), 35.8 (d, JP–C
=
7.11–7.68 (15H, m, PhCH), 7.38 (1H, s, imidNCHC), 9.93
(1H, s, imidNCHN). 13C{1H} NMR (acetonitrile-d3,
67.9 MHz) d 11.5 (CH2CH3), 24.5 (CH2CH3), 26.0, 26.2,
2.7, c-hexCH2), 55.8 (d, JP–C = 27.1, c-hexCHNphos), 61.0
2
(br, c-hexCHNimid), 122.5, 123.0 (aromaticCH), 124.5, 124.6
(
(
BiNapC), 124.9, 125.0, 126.4, 126.5, 127.2, 127.4
aromaticCH), 127.8 (NCHC), 127.9, 128.2, 128.5, 128.7,
3
35.4 (c-hexCH2), 37.6 (d, JP–C = 4.0, c-hexCH2), 52.6
(NCH2CH2), 62.6 (d, JP–C = 27.1, c-hexCHNphos), 65.3
128.8, 129.6, 130.2 (aromaticCH), 130.9 (imidC(Ph)N), 131.4,
131.9 (BiNapC), 133.2, 133.3 (BiNapCipso), 134.3 (PhCipso),
2
3
(d, JP–C = 5.4, c-hexCHNimid), 120.8 (NCHC), 127.2
2
O2BiNap
(
imidC(Ph)N), 129.1, 129.4, 129.5, 129.7, 130.0, 130.5,
135.6 (br, NCHN), 147.8 (d, JP–C = 3.4,
C
),
ipso
2
O2BiNap
131.3 (PhCH), 131.6 (d, JP–C = 23.4, PhCH) 131.9 (d,
2JP–C = 23.3, PhCH), 137.2 (PhCipso), 137.4 (br, NCHN),
150.1
(
C
). 31P{1H} NMR (benzene-d6,
ipso
109.4 MHz) d 149.5 (s, NPO2BiNap(R)).
1
PPh
1
143.2 (d, JP–C = 66.1,
C
ipso
), 143.5 (d, JP–C = 73.5,
PPh
C
ipso
). 31P{1H} NMR (acetonitrile-d3, 109.4 MHz) d
4.12. Synthesis of C(H)N(H)PO2Binap(S) (14)
34.3 (s, NPPh2). Anal. Calc. for C30H35N3BrP: C, 65.69;
H, 6.43; N, 7.66. Found: C, 65.39; H, 6.35; N, 7.51%.
To a stirred solution of 4 (48 mg, 0.20 mmol) in benzene
(2 mL) at 25 ꢁC was added triethylamine (28 lL,
0.20 mmol) and (S)-chlorobinaphthylphosphite (70 mg,
0.20 mmol). The resulting solution was stirred for 5 h
giving a white precipitate. Workup as for 12 gave 14 as a
yellow solid. Yield: 91 mg, 82%. MS (FAB+): m/z 556
(100%) [M + H]+. MS (HRFAB+): Calc. for
C35H31N3O2P: 556.2154. Found: 556.2171. 1H NMR (ben-
zene-d6, 300 MHz) d 0.51–1.85 (8H, m, c-hexCH2), 3.15 (2H,
m, NH + c-hexCHNphos), 3.52 (1H, m, c-hexCHNimid), 6.89–
7.71 (17H, m, aromaticCH), 7.40 (1H, s, imidNCHC), 7.66
(1H, s, imidNCHN). 13C{1H} NMR (benzene-d6, 75.5
4.10. Synthesis of C(H)N(H)PO2BiPh (12)
To a stirred solution of 4 (48 mg, 0.20 mmol) in benzene
(2 mL) at 25 ꢁC was added triethylamine (28 lL,
0.20 mmol)
and
chlorobiphenylphosphite
(50 mg,
0.20 mmol). The resulting solution was stirred for 5 h giv-
ing a white precipitate. The mixture was filtered and the
volatiles removed from the filtrate under reduced pressure
to give 12 as a yellow solid. Yield: 71 mg, 78%. MS
(FAB+): m/z 456 (100%) [M + H]+. MS (HRFAB+): Calc.
1
3
for C27H27N3O2P: 456.1841. Found: 456.1826. H NMR
MHz) d 24.9, 25.1, 34.8 (c-hexCH2), 37.0 (d, JP–C = 2.7,
(benzene-d6, 270 MHz) d 0.43 (1H, m, c-hexCH2), 0.85
(2H, m, c-hexCH2), 1.31 (3H, m, c-hexCH2), 1.78 (2H, m,
c-hexCH2), 2.79 (1H, m, NH), 3.12 (1H, m, c-hexCHNphos),
3.48 (1H, m, c-hexCHNimid), 7.01–7.49 (13H, m, PhCH),
7.53 (1H, s, imidNCHC), 7.73 (1H, s, imidNCHN).
c-hexCH2), 55.1 (d, JP–C = 22.1, c-hexCHNphos), 60.6 (br,
2
c-hexCHNimid), 122.2, 123.2 (aromaticCH), 123.9, 124.5
(
BiNapC), 124.9, 125.0, 126.4, 126.5, 127.2, 127.3 (aromaticCH),
127.7 (NCHC), 128.5, 128.7, 128.8, 128.9, 129.9, 130.0,
130.7 (aromaticCH), 131.3 (BiNapC), 131.4 (imidC(Ph)N),

R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
5829
131.9 (BiNapC), 133.2, 133.3 (BiNapCipso), 133.4 (PhCipso),
(br, c-hexCHNimid), 67.5 (CH(CH3)2), 116.9 (NCHC),
121.6, 122.9 (aromaticCH), 124.0, 124.5 (BiNapC), 125.5,
125.6, 126.7, 126.9, 127.0, 127.2 (aromaticCH), 128.9
2
O2BiPh
136.4 (br, NCHN), 148.5 (d, JP–C = 4.8,
C
),
ipso
2
O2BiPh
150.1 (d, JP–C = 1.3,
C
). 31P{1H} NMR (ben-
ipso
zene-d6, 121.5 MHz) d 149.8 (br, NPO2BiNap(S)).
(
imidC(Ph)N), 129.0, 129.7, 130.2, 130.3, 130.7, 130.9,
131.0 (aromaticCH), 131.6, 131.9 (BiNapC), 133.1 (BiNapCipso),
4.13. Synthesis of [iPrC(H)N(H)PO2BiPh][I] (15)
133.2 (d, JP–C = 1.3,
C
), 136.3 (br, NCHN), 137.3
ipso
3
BiNap
(PhCipso), 146.9 (d, JP–C = 4.8,
C
ipso
), 149.3 (d,
2
O2BiNap
O2BiNap
In an ampoule sealed with a Teflon stopcock a 1,4-diox-
ane solution (2 mL) of 12 (68 mg, 0.15 mmol) and 2-iodo-
propane (20 lL, 0.20 mmol) was stirred at 60 ꢁC for 72 h,
giving a yellow precipitate. Removal of the volatiles under
reduced pressure gave an yellow solid that was dissolved in
CH2Cl2 (0.5 mL) and added drop wise to benzene (10 mL)
to give an off white precipitate that was filtered, washed
with benzene (2 · 5 mL) and dried under reduced pressure
to give 15 as an off white solid. Yield: 73 mg, 78%. MS
(FAB+): m/z 498 (100%) [M + I]+. MS (HRFAB+): Calc.
2JP–C = 2.0,
C
). 31P{1H} NMR (dichlorometh-
ipso
ane-d2, 121.5 MHz) d 150.0 (s, NPO2BiNap). Anal. Calc.
for C38H37N3O2IP: C, 62.90; H, 5.14; N, 5.79. Found: C,
62.84; H, 5.29; N, 5.65%.
4.15. Synthesis of [iPrC(H)N(H)PO2Binap(S)][I] (17)
In an ampoule sealed with a Teflon stopcock a 1,4-diox-
ane solution (2 mL) of 14 (83 mg, 0.15 mmol) and 2-iodopro-
pane (20 lL, 0.20 mmol) was stirred at 60 ꢁC for 72 h, giving
an off white precipitate. Workup as for 16 gives 17 as an off
white solid. Yield: 93 mg, 85%. MS (FAB+): m/z 598
(100%) [M + I]+. MS (HRFAB+): Calc. for C38H37N3O2P:
1
for C30H33N3O2P: 498.2310. Found: 498.2316. H NMR
(dichloromethane-d2, 400 MHz) d 1.16–2.12 (8H, m,
3
c-hexCH2), 1.66 (3H, d, JH–H = 6.7, CH(CH3)2), 1.69
3
1
(3H, d, JH–H = 6.7, CH(CH3)2), 2.18 (1H, m, NH), 3.72–
598.2623. Found: 598.2618. H NMR (dichloromethane-
4.18 (2H, m, c-hexCHNphos
+
c-hexCHNimid), 4.87 (1H, vsep,
d2, 300 MHz) d 1.08–2.79 (8H, m, c-hexCH2), 1.72 (3H, d,
3JH–H = 6.7 Hz, CH(CH3)2), 6.94 (1H, m, BiPhCH), 7.01
(1H, m, BiPhCH), 7.21–7.50 (11H, m, aromaticCH), 7.33
(1H, s, imidNCHC), 10.52 (1H, s, imidNCHN). 13C{1H}
NMR (dichloromethane-d2, 100.5 MHz) d 23.4, 23.8
(CH3), 24.9, 25.4, 32.7, 36.4 (c-hexCH2), 54.5 (CH(CH3)2),
55.4 (d, 2JP–C = 16.8, c-hexCHNphos), 65.4 (br, c-hexCHNimid),
117.6 (NCHC), 121.9, 122.5, 125.5, 126.2 (BiPhCH), 128.7,
129.6, 129.7, 129.8, 130.2, 130.7, 131.0 (aromaticCH), 131.4
3JH–H = 6.8, CH(CH3)2), 1.75 (3H, d, JH–H = 6.8,
3
CH(CH3)2), 3.26 (1H, m, NH), 3.83 (1H, m, c-hexCHNphos),
3
4.17 (1H, m, c-hexCHNimid), 5.03 (1H, vsep, JH–H = 6.8
Hz, CH(CH3)2), 7.10–8.0 (17H, m, aromaticCH), 7.46 (1H, s,
imidNCHC), 10.94 (1H, s, imidNCHN). 13C{1H} NMR
(dichloromethane-d2, 75.5 MHz) d 23.2, 23.9 (c-hexCH2),
2
24.7, 25.2 (CH3), 33.1, 36.2 (c-hexCH2), 55.3 (d, JP–C
= 29.4, c-hexCHNphos), 65.1 (br, c-hexCHNimid), 66.9
(CH(CH3)2), 117.1 (NCHC), 121.8, 122.7 (aromaticCH),
124.2, 124.8 (BiNapC) 125.4, 125.6, 126.7, 126.8, 127.0,
127.2, (aromaticCH), 128.9 (imidazoliumC(Ph)N), 129.1, 129.5,
(
imidC(Ph)N), 131.8, 131.9 (BiPhCipso), 136.1 (NCHN),
2
O2BiPh
136.7 (PhCipso), 149.4 (d, JP–C = 3.8,
C
ipso
), 150.9
O2BiPh
(br,
C
). 31P{1H} NMR (dichloromethane-d2,
ipso
161.8 MHz) d 148.7 (br, NPO2BiPh). Anal. Calc. for
C30H33N3O2IP: C, 57.61; H, 5.32; N, 6.72. Found: C,
57.83; H, 5.30; N, 6.37%.
129.8, 130.1, 130.3, 130.5, 130.9, (aromaticCH), 133.5, 133.7
BiNap
(
C
), 136.6 (NCHN), 137.7 (PhCipso), 147.9 (d, 2JP–C
ipso
O2BiNap
2
O2BiNap
= 4.3,
C
), 150.8 (d, JP–C = 2.0,
ipso
C
ipso
).
31P{1H} NMR (dichloromethane-d2, 121.5 MHz) d 150.4
(s, NPO2BiNap). Anal. Calc. for C38H37N3O2IP: C, 62.90;
H, 5.14; N, 5.79. Found: C, 62.82; H, 5.34; N, 5.70%.
4.14. Synthesis of [iPrC(H)N(H)PO2Binap(R)][I] (16)
In an ampoule sealed with a Teflon stopcock a 1,4-diox-
ane solution (2 mL) of 13 (83 mg, 0.15 mmol) and 2-iodo-
propane (20 lL, 0.20 mmol) was stirred at 60 ꢁC for 72 h,
giving an off white precipitate. The mixture was filtered,
and the residue washed with 1,4-dioxane (2 · 5 mL) and
dried under reduced pressure to give 16 as an off white so-
lid. Yield: 90 mg, 83%. MS (FAB+): m/z 598 (100%)
[M ꢀ I]+. MS (HRFAB+): Calc. for C38H37N3O2P:
4.16. Synthesis of iPrCN(H)PPh2 (18)
To an NMR tube sealed with a Teflon stopcock was
added 7 (60 mg, 0.11 mmol) and sodium bis(trimethylsi-
lyl)amide (20 mg, 0.11 mmol). THF-d8 (ca. 0.7 mL) was
transferred via the gas phase to the tube cooled to
ꢀ196 ꢁC. On thawing the solution was allowed to warm
to ꢀ84 ꢁC, shaken for 5 min and allowed to warm to
25 ꢁC . 1H NMR (THF-d8, 300 MHz) d 0.73–2.13 (8H,
1
598.2623. Found: 598.2625. H NMR (dichloromethane-
d2, 300 MHz) d 1.06–2.76 (8H, m, c-hexCH2), 1.70 (3H, d,
3
3
3JH–H = 6.8, CH(CH3)2), 1.73 (3H, d, JH–H = 6.8,
m, c-hexCH2), 1.41 (3H, d, JH–H = 6.8, CH(CH3)2), 1.42
CH(CH3)2), 2.84 (1H, m, NH), 3.76 (1H, m, c-hexCHNphos),
(3H, d, JH–H = 6.8, CH3), 2.76 (1H, m, NH), 3.78 (1H,
3
4.11 (1H, m, c-hexCHNimid), 5.00 (1H, vsep, JH–H = 6.8 Hz,
m, c-hexCHNphosphine), 3.93 (1H, m, c-hexCHNNHC), 4.45
3
CH(CH3)2), 7.05–7.46 (13H, m, aromaticCH), 7.38 (1H, s,
imidNCHC), 7.81–8.10 (4H, m, aromaticCH), 10.86 (1H, s,
(1H, vsep, JH–H = 6.8, CH(CH3)2), 6.91 (1H, s,
3
NHCNCHC), 6.84–7.47 (15H, m, PhCH). 13C{1H} NMR
(THF-d8, 75.5 MHz) d 24.6, 24.8 (c-hexCH2), 26.5, 26.6
imidNCHN).
13C{1H}
NMR
(dichloromethane-d2,
75.5 MHz) d 23.4, 24.0 (c-hexCH2), 24.9, 25.5 (CH3), 33.2,
(CH3), 36.7 (c-hexCH2), 36.8 (d, JP–C = 8.3, c-hexCH2),
3
36.4 (c-hexCH2), 55.7 (d, JP–C = 26.3, c-hexCHNphos), 65.4
53.3 (CH(CH3)2), 61.8 (d, JP–C = 24.9, c-hexCHNphos),
2
2

5830
R. Hodgson, R.E. Douthwaite / Journal of Organometallic Chemistry 690 (2005) 5822–5831
3
63.4 (d, JP–C = 6.9, c-hexCHNNHC), 115.6 (NCHC), 128.3
the presence of Eu(hfc)3 and comparison to the literature
values [37].
(
NHCC(Ph)N), 128.5, 128.6, 128.7, 129.2, 129.3, 129.6,
130.4 (aromaticCH), 131.6 (d, JP–C = 4.7, PPhCH), 131.0
2
(d, JP–C = 5.4, PPhCH), 135.4 (PhCipso), 145.6 (d,
4.19. General procedure for asymmetric transfer
hydrogenation
2
1JP–C = 14.5,
C
), 145.8 (d, JP–C = 18.0,
C
ipso
),
PPh
1
PPh
ipso
212.7 (NCN). 31P{1H} NMR (THF-d8, 121.5 MHz) d
33.6 (s, NPPh2).
To a THF solution (1 mL) of an imidazolium–phos-
phine (10 lmol) cooled to ꢀ84 ꢁC was added dropwise a
solution of sodium bis(trimetylsilyl)amide (2 mg, 11 lmol)
in THF (1 mL). The solution was stirred for 10 min at
ꢀ84 ꢁC and subsequently added dropwise to a solution of
[Ir(COD)Cl]2 (3.4 mg, 5 lmol) in THF (1 mL) at ꢀ84 ꢁC.
The solution was stirred for 10 min at ꢀ84 ꢁC, allowed to
warm to 25 ꢁC and stirred for a further 1 h. The volatiles
were removed under reduced pressure and the solid dis-
solved in (CH3)2CHOH (1 mL) and added to a stirred solu-
tion of acetophenone (235 lL, 2.0 mmol) and KOH
(2.8 mg, 50 lmol) in (CH3)2CHOH (4 mL) at 80 ꢁC. The
resulting solution was stirred at 80 ꢁC for the required
length of time. Intermittently aliquots were removed, di-
luted with CH2Cl2, run through a silica plug and analysed
by chiral GC. GC conditions: Chiralsil-Dex CB,
(25 m · 0.25 mm · 0.25 lm), 80 ꢁC, 1 lL split injection
(190 ꢁC), FID detection (190 ꢁC), Helium (15 psi). Abso-
lute configuration was assigned by comparison to authenti-
cated enantiomers of B.
4.17. Synthesis of iPrCN(H)PO2BiPh (19)
To an NMR tube sealed with aTeflon stopcock was added
15 (g, mmol) and sodium bistrimethylsilylamide (g, mmol).
THF-d8 (ca. 0.7 mL) was transferred via the gas phase to
the tube cooled to ꢀ196 ꢁC and the sample treated as for
18. 1H NMR (THF-d8, 300 MHz) d 0.84–1.96 (8H, m,
3
c-hexCH2), 1.59 (3H, d, JH–H = 6.7, CH(CH3)2), 1.64 (3H,
3
d, JH–H = 6.7, CH(CH3)2), 2.74 (1H, m, NH), 3.62 (1H,
m, c-hexCHNphosphine), 4.13 (1H, m, c-hexCHNNHC), 4.93
3
(1H, vsep, JH–H = 6.7, CH(CH3)2), 6.81 (1H, m, BiPhCH),
6.92 (1H, m, BiPhCH), 7.12–8.04 (11H, m, PhCH), 7.30 (1H,
s, NHCNCHC). 13C{1H} NMR (THF-d8, 75.5 MHz) d
23.2, 23.4 (CH3), 25.7, 26.0, 29.5, 35.2 (c-hexCH2), 54.7
2
(CH(CH3)2), 55.5 (d, JP–C = 16.6, c-hexCHNphosphine), 64.8
(br, c-hexCHNNHC), 114.3 (NCHC), 121.1, 121.8, 123.2,
123.6 (BiPhCH), 129.2 (NHCC(Ph)N), 126.5, 127.2, 130.1,
130.4,130.8, 131.4, 131.9(aromaticCH), 132.1, 133.1(BiPhCipso),
OBiPh
137.9 (PhCipso), 151.2, 151.5 (br,
C
), 216.2 (NCN).
ipso
31P{1H} NMR (THF-d8, 121.5 MHz)
NPO2BiPh).
d
152.4 (s,
Acknowledgements
The authors thank EPSRC and the University of York
for financial assistance.
4.18. General procedure for asymmetric allylic substitution
catalysis
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