Highly efficient synthesis of (Phosphinodihydrooxazole)- (1,5-cyclooctadiene) Iridium complexes

Article abstract of DOI:10.1515/znb-2009-1007

A highly efficient one-pot procedure for the synthesis of complexes of the type [Ir(COD)(Phox)]X, where Phox is a (chiral) phosphinooxazoline ligand, X = PF₆ or B[(3,5-(CF₃)₂C₆H ₃)]₄ (BARF), is developed. Former reported syntheses demanded the isolation of pure ligands by column chromatography, but the ligands tend to adsorb irreversibly on silica. Moreover, the chromatography has to be performed with careful exclusion of air. The present method avoids this difficulties. The yields of the syntheses are comparable with those starting from the pure ligands. The method is also suitable for the preparation of complexes of the type [Rh(COD)(Phox)]BARF and [Rh(Phox)₂]BARF.

Full text of DOI:10.1515/znb-2009-1007

Highly Efficient Synthesis of (Phosphinodihydrooxazole)-
(1,5-cyclooctadiene) Iridium Complexes
Volodymyr Semeniuchenkoa,b, Volodymyr Khilyab, and Ulrich Grotha
a Fachbereich Chemie und Konstanz Research School Chemical Biology, Universita¨t Konstanz,
78457 Konstanz, Germany
b Department of Chemistry, National Taras Shevchenko University, Kyiv, Ukraine
Reprint requests to Dr. Volodymyr Semeniuchenko. Fax: +497531884155.
E-mail: chem vova@mail.univ.kiev.ua
Z. Naturforsch. 2009, 64b, 1147 – 1158; received June 7, 2009
A highly efficient one-pot procedure for the synthesis of complexes of the type [Ir(COD)(Phox)]X,
where Phox is a (chiral) phosphinooxazoline ligand, X = PF6 or B[(3,5-(CF3)2C6H3)]4 (BARF), is
developed. Former reported syntheses demanded the isolation of pure ligands by column chromatog-
raphy, but the ligands tend to adsorb irreversibly on silica. Moreover, the chromatography has to be
performed with careful exclusion of air. The present method avoids this difficulties. The yields of the
syntheses are comparable with those starting from the pure ligands. The method is also suitable for
the preparation of complexes of the type [Rh(COD)(Phox)]BARF and [Rh(Phox)2]BARF.
Key words: Iridium, Rhodium, Chiral Ligand, Homogeneous Catalysis, Heterocycles
Introduction
O
N
Chiral phosphinodihydrooxazole complexes of irid-
ium are valuable catalysts which are used in homoge-
neous enantioselective hydrogenation. In a pioneering
work of A. Lightfoot, P. Schnider and A. Pfaltz, com-
plexes of type 4 (see Scheme 2) were shown to cat-
alyze enantiospecific hydrogenation of stilbenes and
styrenes [1]. Imines were also hydrogenated with high
enantioselectivity [2]. Enantioselective hydrogenation,
catalyzed by these complexes, could also be carried
out in supercritical CO2 [3, 4]. Recently, we have
found a new reaction for the homogeneous hydro-
genation of electron-deficient alkenes, catalyzed by
complexes of the type [Ir(COD)(PˆN)]BARF (COD
stands for 1,5-cyclooctadiene, BARF for tetrakis(3,5-
bis(trifluoromethyl)phenyl)borate, PˆN for a κ2-P,N-
coordinated ligand) in the presence of ethyldiiso-
propylamine [5].
M
e
t
h
o
LG
N
d
−
s
1
X
N
1. [Ir(COD)Cl]2
CH2Cl2
−
6
R
O
O
7
d
o
+
Ir
h
t
2. NaBARF
or KPF6
Ar2P
e
N
PAr2
M
R
R
PAr2
Method 1: LG = F; Ar2PLi
Method 2: LG = H; 1. s-BuLi, TMEDA; 2. Ar2PCl
Method 3: LG = OTf; Ar2PK
Method 4: LG = Br; Mg, Ar2PCl
Method 5: LG = Br; CuI, MeNHCH2CH2NHMe, Cs2CO3, Ar2PH
Method 6: LG = I; Ar2PH, NEt3, Pd(OAc)2
Method 7: NH2CHRCH2OH, ZnCl2, then bipy
Scheme 1. Methods for the synthesis of phox ligands and the
corresponding iridium complexes.
phy. Ligand 3c (Scheme 2) has been described as an
air-stable compound [8], but in our experiments this
was not the case. The chromatography must be per-
Current methods for the syntheses of these com- formed strictly under nitrogen on deoxygenated sor-
plexes comprise the syntheses of the ligands, their iso- bens using deoxygenated eluent, otherwise the phos-
lation and purification (via column chromatography), phine oxide derived from 3c is detected by 31P NMR.
followed by complexation on iridium (Scheme 1).
The main problem was the irreversible adsorption of
According to the push-pull phosphinylation mecha- the ligand on silica, neutral or basic alumina, such that
nism [6], method 1 [7] requires an excess of phosphine, it remained in the column even when triethylamine was
which prevents crystallization of the ligand, which thus added to the eluent. The irreversible adsorption low-
must be separated by column chromatography. In our ered the yield of the ligand to 20 – 30 %. Method 2 [9]
hands, method 1 was reproducible up to chromatogra- gave the desired phosphinooxazolines with a best GC
c
0932–0776 / 09 / 1000–1147 $ 06.00 ꢀ 2009 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
Scheme 2. One-pot synthesis of complexes of the type [Ir(COD)(Phox)]X. Reagents and conditions: i: 1.1 eq. nBuLi, Et2O,
5 min or MTBE, 30 min (for 1g, 1i), r. t.; ii: 1 eq., stiring in Et2O at r. t. or reflux in MTBE, 10 h (2); iii: [Ir(COD)Cl]2,
CH2Cl2, 2 – 4 h, reflux; iv: NaBARF or KPF6, CH2Cl2, 1 – 4 h.
−
yield of 20 %, and hence was not further explored. Ac- tion by ether (those with the PF6 anion). The com-
cording to ref. [10], method 3 gives impure ligand, and plexes are colored which makes monitoring of the col-
hence chromatography is necessary. Methods 4 [7], umn chromatography extremely simple, because there
5 [11], 6 [12] and 7 [13, 14] also require column chro- is no need of fraction collecting.
matography.
The identity of the synthesized complexes was con-
firmed by 1H, 13C and 31P NMR spectra and by HRMS
ESI/FT-ICR. Compounds 4c [1, 15], 4f [1, 15], 4i [15]
and 4l [15] are described in the literature, but the NMR
spectra for 4i and 4l have not been reported.
Results and Discussion
In order to obtain the required complexes we de-
veloped the following one-pot procedure (Scheme 2).
The preparation of the ligand has also been simpli-
fied compared to that in ref. [7]. Although the possi-
bility of complexation of impure ligand was indicated
in the literature, the particular procedure was either not
described [15], or the crude ligand was only filtered
through a plug of silica gel [16].
Chiral 2-(2-fluorophenyl)-4-R-4,5-dihydrooxazoles
2 are normally synthesized from aminoalcohols, the
latter being derivatives of natural and synthetic chiral
amino acids (except 2h). Although it would be possi-
ble to synthesize the complex 2b in enantiomerically
pure form from chiral alaninol, for our purposes (the
above mentioned DIPEA-activated Ir-catalyzed hydro-
genation) we needed only a racemic complex.
n-Butyllithium was used to deprotonate the diaryl-
or dialkylphosphines. Although according to ref. [17]
the use of s-BuLi is preferred, it does not result
in a better yield of complex 4. The use of THF is
avoided in the ligand preparation (except 4m). THF
is known to slowly react with lithium diphenylphos-
phide [18– 20], thus decreasing the yield of the
desired ligand. Sterically unhindered diphenylphos-
phine and hindered di-o-tolyl-, dixylyl- and dicy-
clohexylphosphine readily enter in the phosphinyla-
tion reaction, giving the corresponding ligands and
complexes, but hindered phosphines must be de-
protonated during 30 min in MTBE, and then re-
fluxed overnight with fluoroxazoline 2c (otherwise
the conversion of 2c is incomplete). Lithium di-
Compounds 4 are insensitive to oxygen and mois- tert-butylphosphide, bis(trimethylsilyl)phosphide and
ture and could be purified by column chromatography phospholan-1-ide failed to enter in this reaction, i. e.
(preferably those with BARF as anion) or precipita- ligand formation was not detected.
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
1149
ity is only possible for a cis-arrangement (3JCCCP
≈
3
2
4.4 Hz, JCNRhP ≈ 4.4 Hz, JCNRh ≈ 1.5 Hz). The
fine structure was seen only on a 100 MHz instrument
(Varian UNITYINOVA), while the 13C NMR spectrum,
acquired on a 150 MHz (Bruker Avance DRX600)
spectrometer, showed a broad singlet. The carbons
1-C, 3ꢀꢀ-CH, 1ꢀꢀ-C and 2ꢀꢀ-CH (numbering is shown in
Fig. 1, Experimental Section) of complex 6 give rise to
pseudo-triplets in the 13C NMR spectrum representing
AXXꢀZ spin systems (A = 13C, X,Xꢀ = 31P, Z = Rh).
Using this protocol, (4S)-2-(2-(diphenylarsino)-
phenyl)-4-isopropyl-4,5-dihydrooxazole (7) was syn-
thesized from the oxazoline 2c and lithium dipheny-
larsinide. The complexes [Ir(COD)(7)]BARF and
[Ir(COD)(7)]PF6 were found to be inherently unstable
at r. t. and were detected only by mass spectrometry.
The complex [Ir(COD)(7)]BARF was a weak hydro-
genation catalyst of stilbene, that is why its research
was discontinued.
Scheme 3. Synthesis of pure 4i.
The NMR spectra of complexes 4 – 6 are compli-
cated because the signals in the proton spectra are not
fully resolved (in both aromatic and aliphatic parts),
and the chirality makes the atoms of phenyl rings and
of COD magnetically nonequivalent. With the help
of 2D techniques (HMBC, HSQC, COSY, TOCSY,
ROESY and J-resolved) most assignments could be
made. Not resolved multiplets (nrm) are inherent for
Scheme 4. Preparation of the Rh complexes 5 and 6.
Complex 4i and dicyclohexylphosphine oxide are
coeluted by dichloromethane and could not be sepa-
rated even by hexane-dichloromethane gradient chro-
matography.The analytically pure complex 4i was syn-
thesized from 4l (Scheme 3). The latter was purified
by precipitation with ether from a dichloromethane
solution.
Complex 4g was obtained in impure form. All
attempts to purify it by gradient chromatography
(hexane-dichloromethane or hexane-c−hloroform) were
unsuccessful. The complex with PF6 as counter-ion
was also obtained in an impure state, and the above-
mentioned strategy with anion exchange was not appli-
cable for 4g. However, the formation of 4g was proven
by its mass spectrum.
Being successful in the synthesis of the Ir com-
plexes, we checked the possibility of synthesizing the
analogous Rh complexes (Scheme 4). With 1 eq. of lig-
and for 1 eq. of Rh, complex 5 was synthesized. COD
bound to Rh is more labile than that bound to Ir, there-
fore an excess of ligand yielded complex 6.
1
the H NMR spectra of these complexes. Although
the shifts of individual peaks are indistinguishable in
1D spectra, the precise 1H NMR shifts could be estab-
lished from HSQC and HMBC experiments. 2D spec-
tra were not measured for compounds 4c and 4f, be-
cause their spectra are in agreement with the ones
found in the literature.
Complex 4e has very interesting spectral properties.
While the other compounds show a sharp 31P NMR
singlet, 4e shows two broad singlets at δ = +16.1
and +8.5 ppm in CDCl3. The conformational stabil-
ity known for tri-o-tolylphosphine [21] forced us to
examine high-temperature 31P NMR spectra of this
compound. At 140 ◦C and higher temperatures the so-
lution of 4e in 1,2,4-trichlorobenzene shows a sharp
singlet at δ = +12.5 ppm (line width 53.4 Hz),
where◦as on cooling this singlet begins to broaden, and
at 60 C two broadened singlets appear. The approxi-
mate coalescence temperature in this solvent is 80 ◦C.
Because of the strong trans-effect of the phosphorus The 1H NMR spectrum of this compound accord-
atom, the ligands in complex 6 are expected to be cis- ingly shows only broad lines.◦The complex reacts with
arranged. The iminic carbon gives rise to a triplet of DMSO when heated at 140 C. Therefore a resolved
doublets in the 13C NMR spectrum, and this multiplic- 1H NMR spectrum of this compound which is in fast
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1150
V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
conformational equilibrium cannot be obtained. How-
ever, cooling to −40 ◦C gave sharp peaks in the 1H, 13
C
and 31P NMR spectra. Based on the relative integral in-
tensity of the 31P NMR signals (recorded without pro-
ton decoupling), the relative concentration of conform-
ers at −40 ◦C is 1 : 0.75 (at δ = +16.1 and +8.5 ppm,
respectively). A full assignment of the NMR spectra
of this complex cannot be achieved, since broad peaks
in 1D NMR experiment result in low cross peaks in
HSQC and HMBC spectra.
Fig. 1. Atom numbering for compounds 4 – 6, used for the
Further proof of the identity of complexes 4 – 6 is
provided by the mass spectra (with isotopic clusters)
and the ability of the synthesized compounds to per-
form hydrogenation of stilbene under 100 bar of hydro-
gen in dichloromethane or toluene solution (except 6).
As expected, the hydrogenation of stilbene in toluene
was inhibited by ethyldiisopropylamine [15, 22, 23].
assignment of NMR spectra.
ence standards are: TMS (internal) for 1H and for 31C NMR,
85 % H3PO4 (external) for 31P NMR, Et2O · BF3 (external)
for 11B NMR, CFCl3 (internal) for 19F NMR. “Nrm” stands
for not resolved multiplet. In order to define the arrange-
ment of ligands, the 13C NMR spectrum of complex 6 was
obtained using special parameters (spectral width +175 –
−5 ppm, 256000 points, acquisition time 7.0736 sec, relax-
ation delay 1 sec) on a UNITYINOVA 400 instrument. The
numbering of atoms for compounds 4 – 6, used for assign-
ment of the NMR spectra, is shown in Fig. 1 (2ꢀ and 6ꢀ,
3ꢀ and 5ꢀ, 2ꢀꢀ and 6ꢀꢀ as well as 3ꢀꢀ and 5ꢀꢀ are inequivalent
only for complexes 4e, 4g and 4h).
Conclusion
By using an easy synthetic procedure, complexes
of the general formula [Ir(COD)(Phox)]BARF and
[Ir(COD)(Phox)]PF6 were synthesized without isola-
tion of the air-sensitive free ligands. By using this
method two complexes of rhodium (5 and 6) were also
synthesized. For compounds not fully characterized in
the literature, full assignments of the NMR spectra
were carried out. Complex 4e was found to exist as
a mixture of two stable conformers at r. t.
All complexes bearing the BARF counter-ion, have shown
the following signals in NMR spectra: 1H NMR (CDCl3,
600 MHz): δ = 7.54 (br s, 4 H, 4-HBARF), 7.74 (br s, 8 H,
1
2-HBARF). – 13C{ H} NMR (CDCl3, 150 MHz): δ = 117.50
(br s, 4-CHBARF), 124.55 (q, J = 273 Hz, CF3), 128.9 (br
q, J = 30 Hz, 3-CBARF), 134.81 (br s, 2-CHBARF), 161.72
(q 1 : 1 : 1 : 1, J = 50.5 Hz, 1-CBARF). – 19F NMR (CDCl3,
376 MHz): δ = −62.8. – 11B NMR (CDCl3, 128 MHz):
δ = −6.9.
Experimental Section
If not stated otherwise, solvents were dried and de-
gassed by distillation over Na/K alloy (or CaH2 for
dichloromethane) in nitrogen atmosphere and stored un-
der nitrogen. Diphenylphosphine was obtained from MCAT
as a gift. [Ir(COD)Cl]2 was purchased from Chempur or
obtained from Umicore as a gift. The other compounds
were purchased from Sigma-Aldrich, Fluka, Acros, ABCR,
and Fluorochem, or synthesized by known procedures:
NaBARF [24], oxazolines [7]. GC/MS was performed on an
CAUTION. All diarylphosphines, dialkylphosphines,
lithium diaryl- and dialkyphosphides, and all ligands 3 are
very toxic and pyrophoric compounds. All operations must
be carried out strictly under inert gas in a well-ventilated
fume hood or in a glovebox.
Synthesis of bis(2,6-dimethylphenyl)phosphine oxide
In 50 mL of absolute Et2O, 2,6-dimethylbromobenzene
HP GC/MS 5890/5972 instrument (EI, 70 eV) equipped with (18.506 g, 0.1 mol) and magnesium (2.674 g, 0.11 mol) were
a Phenomenex Zebron ZB-5 column (30 m × 0.25 mm × mixed in a nitrogen atmosphere. One crystal of iodine was
0.25 µm). Helium was used as carrier gas. HRMS ESI/FT- added, and the mixture was heated by a heatgun. After the
ICR spectra were recorded on a Bruker APEX II FT/ICR formation of the Grignard reagent had started, the mixture
instrument with a 7 Tesla magnet in positive polarization. was refluxed for 3 h until the magnesium was dissolved. The
Rotation angles were measured on a Perkin-Elmer 241 po- mixture was cooled to ca. −100 ◦C with liquid nitrogen, and
larimeter with 5 sec integration time. We used chloroform, diethyl phosphite (3.8 mL, 0.03 mol) was added. The mixture
stabilized with 1 % of ethanol (Acros) for measurement of was warmed to r. t. and refluxed overnight (ca. 10 h), cooled
the rotation angles. NMR spectra were recorded on Bruker and poured into 200 mL of 1N aqueous HCl. The layers were
Avance DRX600 (600 MHz), Jeol JNM-LA 400 (400 MHz), separated, the aqueous phase washed with dichloromethane
or Varian UNITYINOVA 400 (400 MHz) instruments. Refer- (5 × 100 mL), the united organic phases were dried with
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
1151
Na2SO4, filtered, and evaporated. The residue was recrystal- etate (1 g, 3.63 mmol) in 20 mL THF (under nitrogen)
lized from EtOAc to give white crystalline dixylylphosphine and cooled to −20 ◦C. The borane-dimethylsulfide com-
oxide (4.768 g, 61 %). The substance is moderately air-stable plex (94 %, Acros, 1.4 mL, 14.72 mmol) was added, and
even in solution, but should be stored in the crystalline state the mixture was heated and refluxed for 3 h, then cooled
in a nitrogen-filled glovebox. – 1H NMR (CDCl3, 400 MHz): to −20 ◦C, and 1N HCl (3.4 mL) was added under air
δ = 2.44 (s, 12 H, Me), 7.04 (s, 4 H, 3-H), 7.29 (br t, J = which resulted in refluxing. After cooling, the mixture was
7 Hz, 2 H, 4-H), 8.61 (d, J = 478 Hz, 1 H, PH). – 13C NMR poured into 2N KOH and five times extracted with CH2Cl2.
(CDCl3, 100 MHz): δ = 20.74 (d, J = 8.0 Hz), 129.32 (d, The organic extracts were dried with Na2SO4, filtered and
J = 98 Hz), 129.71 (d, J = 9.6 Hz), 131.81 (d, J = 2.4 Hz), evaporated, giving pure white rac-cis-2-amino-3,3-dimethyl-
141.77 (d, J = 10.4 Hz). – 31P NMR (CDCl3, 161 MHz): δ = 2,3-dihydro-1H-inden-1-ol. This substance is very unstable
+10.88 (d, J = 478 Hz).
and epimerizes upon storage, and should be used within
2 – 3 d. The method can be scaled up to 20 g of rac-2-
(acetoxyimino)-3,3-dimethyl-2,3-dihydro-1H-inden-1-yl ac-
etate. Although in the original article [27] the use of the
borane-THF complex is described, this leads to a mixture,
where the target compound was not detected. A communica-
tion with Atsushi Sudo (author of article [27]) revealed that
the borane-dimethylsulfide complex should be used.
Synthesis of bis(2,6-dimethylphenyl)phosphine (1g)
Compound 1g was synthesized with a yield of 69 %
from bis(2,6-dimethylphenyl)phosphine oxide by stirring
at 70 ◦C with triisobutylaluminum in toluene for 48 h, by the
known procedure [25]. White crystals. – 1H NMR (C6D6,
400 MHz): δ = 2.22 (s, 12 H, CH3), 5.26 (d, J = 231 Hz,
1 H, PH), 6.83 (dd, J = 7.4 Hz, J = 2.3 Hz, 4 H, 3-H), 6.97 (t,
Synthesis of (3aR,8bS)-2-(2-fluorophenyl)-4,4-dimethyl-
4,8b-dihydro-3aH-indeno[2,1-d]oxazole (2h)
J = 7.4 Hz, 2 H, 4-H). – 13C{ H} NMR (C6D6, 100 MHz):
1
δ = 22.93 (d, J = 10.4 Hz, CH3), 128.48 (s, 4-C), 128.63 (d,
J = 2.4 Hz, 3-C), 133.38 (d, J = 17.7 Hz, 1-C), 142.56 (d, J =
12.0 Hz, 2-C). – 31P NMR (C6D6, 161 MHz): δ = −91.60
(d, J = 231 Hz).
rac-cis-2-Amino-3,3-dimethyl-2,3-dihydro-1H-inden-1-
ol was resolved as described in the literature [27]. In abso-
lute dioxane under nitrogen (1S,2R)-2-amino-3,3-dimethyl-
2,3-dihydro-1H-inden-1-ol (1.665 g, 9.4 mmol) and NEt3
◦
(2.6 mL, 19 mmol) were dissolved. With cooling to 0 C,
Synthesis of rac-2-(acetoxyimino)-3,3-dimethyl-2,3-dihydro-
1H-inden-1-yl acetate
2-fluorobenzoyl chloride (1.2 mL, 9.9 mmol) was added,
and the mixture was stirred for 8 h at r. t. SOCl2 (13.4 mL,
184.7 mmol) was added (cooling to 0 ◦C), and the mix-
ture was stirred for 2 h, then evaporated in vacuo at
r. t. The residue was suspended in 5N NaOH and ex-
tracted five times with CH2Cl2. After drying of the ex-
tracts with Na2SO4, filtration and evaporation of the sol-
vent the residue was redissolved in absolute Et2O. Na2SO4
(3.4 g, 23.9 mmol) and NaOH dust (Aldrich, 3.4 g, 85 mmol)
were added, and the mixture was stirred for 48 h at r. t.
in a sealed flask. Water was added, and the organic layer
was separated. Adsorption on silica with subsequent col-
umn chromatography on 200 g of silica (Et2O-pentane 2 : 3)
gave crystalline off-white (3aR,8bS)-2-(2-fluorophenyl)-4,4-
dimethyl-4,8b-dihydro-3aH-indeno[2,1-d]oxazole (2h) with
a yield of 30 %. Unfortunately, the target compound is only
a by-product. The formula of the main product, which is less
polar and elutes first from the column, was not assigned. The
spectral properties of 2h correspond to those published [28].
A three-necked 1 L flask equipped with a reflux
condenser was charged with a solution of 2-(hydroxyimino)-
3,3-dimethyl-2,3-dihydro-1H-inden-1-one [26] (18.4 g,
97 mmol, recrystallized from toluene) in 4◦60 mL of
methanol (under nitrogen) and cooled to −20 C. NaBH4
(16.56 g, 438 mmol) was added, and the mixture was
stirred for 1 h with cooling (the reaction is so vigorous, that
reflux begins), then for 10 h in an ice bath. The mixture
was evaporated in vacuo and suspended in 368 mL of
pyridine (with vigorous shaking under nitrogen). Acetic
anhydride (184 mL) was added, and vigorous shaking
continued, resulting in a violet color which changed to
yellow within 30 sec. After 12 h the mixture was evaporated
in vacuo, and the residue was triturated in 800 mL of
water to give crude rac-2-(acetoxyimino)-3,3-dimethyl-2,3-
dihydro-1H-inden-1-yl acetate. It was recrystallized from a
mixture toluene/hexane (1 : 3) to give white crystals with a
yield of 70 %.
General procedure A for the synthesis of 4a – e, 4f, 4k
and 4j
Synthesis of rac-cis-2-amino-3,3-dimethyl-2,3-dihydro-1H-
inden-1-ol
Diphenylphosphine (1a) (61 mg, 0.33 mmol, for com-
A three-necked 100 mL flask equipped a with re- plexes 4a – d, 4k, 4j) or di(o-tolyl)phosphine (1e) (71 mg,
flux condenser was charged with a solution of rac-2- 0.33 mmol, for complexes 4e, 4f) was dissolved in diethyl
(acetoxyimino)-3,3-dimethyl-2,3-dihydro-1H-inden-1-yl ac- ether (4 mL), and n-BuLi (1.6 M solution in hexane, 0.21 mL,
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
0.33 mmol) was added at r. t., and the yellow mixture was and 4ꢀ-H), 8.05 (m, 1 H, 6-H), and the signals of BARF. –
1
stirred for 5 min. Oxazoline (2a – d, 2k, 0.3 mmol) was added 13C{ H} NMR (CDCl3, 150 MHz): δ = 32.13 (d, J =3.4 Hz,
to the reaction mixture, and the reaction mixture was stirred 4- and 8-CH2COD), 29.70 (3- and 7-CH2COD), 54.55 (NCH2),
overnight. At this point, gas chromatography with a mass- 64.28 (5- and 6-CHCOD), 68.39 (OCH2), 95.14 (d, J =
sensitive analyzer was performed, which showed a conver- 11.5 Hz, 1-2 and 2-CHCOD), 126.20 (d, J = 60 Hz, 1ꢀ-C),
sion of 2 of over 90 % into ligand 3. The mixture was evap- 128.68 (d, J = 8.8 Hz, 1-C), 129.36 (d, J = 9.9 Hz, 3ꢀ-CH),
orated in a stream of nitrogen. [Ir(COD)Cl]2 (100.8 mg, 129.39 (d, J = 46.1 Hz, 2-C), 132.15 (d, J = 1.6 Hz, 5-CH),
0.15 mmol) and CH2Cl2 (3 mL) were added to the residue, 132.47 (d, J = 2.4 Hz, 4ꢀ-CH), 133.23 (d, J = 9.9 Hz, 3-CH),
and the mixture was refluxed for 2 h and cooled. The an- 133.35 (d, J = 8.0 Hz, 6-CH), 133.89 (d, J = 6.9 Hz, 4-CH),
ion exchange can be carried out in air. The procedure can be 134.18 (d, J = 12.1 Hz, 2ꢀ-CH), 165.68 (d, J = 8.0 Hz,
scaled up to 400 mg of [Ir(COD)Cl]2. The complexes of this N =C), and the signals of BARF. – 31P NMR (CDCl3,
type (with various anions) are found to be unstable in toluene 161 MHz): δ = +16.1. – HRMS ESI/FT-ICR: isotope clus-
on storage (toluene being metallated).
ter 630 – 634, found (calcd.): 630.1679, 66 % (630.1671,
60 %); 631.1721, 21 % (633.1728, 31 %); 631.1856, 12 %
(631.1704, 19 %); 632.1688, 100 % (632.1694, 100 %);
633.1714, 33 % (633.1728, 31 %); 634.1739, 7 % (634.1761,
5 %).
Exchange of Cl by BARF
NaBARF (292 mg, 0.33 mmol) was added to the re-
action mixture with stirring at r. t. for 1 – 3 h. The ex-
change could be monitored by TLC on silica gel eluting
with dichloromethane (Rf of [Ir(COD)Cl(Phox)] is 0, that of
[Ir(COD)(Phox)]BARF is 0.75 – 1). Then silica gel (1 g) was
added, and the mixture was evaporated under vacuum at r. t.
This silica was placed on top of the column filled with 20 g of
silica gel, and the desired colored complex was eluted with
CH2Cl2. The eluant was evaporated in vacuo (without heat-
ing), and the complex was dried in a vacuum (10−2 mbar).
Racemic (2-(2-(diphenylphosphino)phenyl)-4-methyl-
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4b)
Yield: 80 %. Red crystals. Very stable on storage at r. t.
even in CDCl3 solution (6 month). – 1H NMR (CDCl3,
600 MHz): δ = 1.05 (d, J = 5.7 Hz, Me), 1.47 (nrm, 1 H,
a-4-HCOD), 1.65 (nrm, 1 H, a-8-HCOD), 2.03 (nrm, 1 H,
e-4-HCOD), 2.06 (nrm, 1 H, e-8-HCOD), 2.45 (nrm, 3 H,
a-7-HCOD and 3-HCOD), 2.53 (nrm, 1 H, e-7-HCOD), 3.14 (br
m, 1 H, 5-HCOD), 3.36 (br m, 1 H, 6-HCOD), 4.18 (dd, J =
9.0 Hz, J = 3.9 Hz, 1 H, OCH2), 4.27 (br s, 1 H, NCHMe),
4.46 (d, J = 9.0 Hz, 1 H, OCH2), 4.97 (br s, 2 H, 1- and
2-HCOD), 7.14 (dd, J = 11.3 Hz, J = 6.6 Hz, 2 H, 2ꢀ-H),
7.41 (nrm, 1 H, 3-H), 7.46 (nrm, 2 H, 3ꢀ-H), 7.47 (nrm, 1 H,
4ꢀ-H), 7.48 (nrm, 2 H, 3ꢀꢀ-H), 7.55 (nrm, 1 H, 4ꢀꢀ-H), 7.60
(nrm, 4 H, 4-, 5- and 2ꢀꢀ-H), 8.07 (m, 1 H, 6-H), and the sig-
Exchange of Cl by PF
6
A solution of KPF6 (184 mg, 1 mmol) in water (2 mL) was
added to the reaction mixture. The two-phase system was
vigorously stirred for 2 h, the exchange being monitored with
TLC on silica gel with CH2Cl2-MeOH (20 : 1) as eluent. The
organic layer was separated, and the aqueous residue was
extracted 5 times with CH2Cl2. Combined organic extracts
were dried over Na2SO4, filtered and evaporated at r. t. The
residue was redissolved in a minimum amount of CH2Cl2,
and the target complex was precipitated with 100 mL of
Et2O, filtered, washed off from the filter with CH2Cl2, evap-
orated at r. t. and dried in a vacuum (10−2 mbar).
1
nals of BARF. – 13C{ H} NMR (CDCl3, 150 MHz): δ =
23.16 (Me), 26.47 (8-CH2COD), 28.59 (4-CH2COD), 32.22
(3-CH2COD), 36.06 (7-CH2COD), 61.52 (NCHMe), 63.80
(6-CHCOD), 63.92 (5-CHCOD), 74.24 (OCH2), 93.54 (d, J =
13.2 Hz, 1-CHCOD), 96.49 (d, J = 12.1 Hz, 2-CHCOD), 117.5
(br s, 4-CHBARF), 121.81 (d, J = 58.3 Hz, 1ꢀ-C), 128.65 (d,
J = 29.7 Hz, 2-C), 128.98 (d, J = 11.0 Hz, 3ꢀ-CH), 129.12
(d, J = 50.6 Hz, 1ꢀꢀ-C), 129.60 (d, J = 11.0 Hz, 3ꢀꢀ-CH),
129.70 (d, J = 15.4 Hz, 1-C), 132.23(d, J = 3.3 Hz, 4ꢀ-CH),
132.25 (br s, 5-CH), 132.70 (d, J = 2.2 Hz, 4ꢀꢀ-CH), 133.11
(2-(2-(Diphenylphosphino)phenyl)-4,5-dihydrooxazole)-
4
(η -1,5-cyclooctadiene)iridium(I) tetrakis(3,5-bis(trifluoro-
methyl)phenyl)borate (4a)
Yield: 74 %. Red crystals. Unstable on storage at r. t. (d, J = 9.9 Hz, 2ꢀ-CH), 133.39 (br s, 3-CH), 133.46 (d,
even in crystalline form (should be stored at −20 ◦C). – J = 7.7 Hz, 6-CH), 133.99 (d, J = 6.6 Hz, 4-CH), 134.96
1H NMR (CDCl3, 600 MHz): δ = 1.93 (m, 2 H, a-4-HCOD (d, J = 12.1 Hz, 2ꢀꢀ-CH), 163.73 (d, J = 6.6 Hz, N =C),
and a-8-HCOD), 2.05 (m, 2 H, a-3-HCOD and a-7-HCOD), and the signals of BARF. – 31P NMR (CDCl3, 161 MHz):
2.26 (m, 4 H, e-3-HCOD, e-4-HCOD, e-7-HCOD, e-8-HCOD), δ = +17.6. – HRMS ESI/FT-ICR: isotope cluster 644 – 648,
3.16 (br s, 2 H, 5- and 6-HCOD), 4.09 (t, J = 10 Hz, 2 H, found (calcd.): 644.1833, 57 % (644.1827, 60 %); 645.1880,
NCH2), 4.48 (t, J = 10 Hz, 2 H, OCH2), 5.08 (br s, 2 H, 18 % (645.1861, 19 %); 646.1851, 100 % (646.1851, 100 %);
1- and 2-HCOD), 7.43 (dd, J = 11.4 Hz, J = 8.2 Hz, 4 H, 647.1901, 34 % (647.1884, 33 %); 648.1949, 6 % (648.1918,
2ꢀ-H), 7.49 (m, 6 H, 3-, 4- and 3ꢀ-H), 7.60 (m, 3 H, 5- 5 %).
Unauthenticated
Download Date | 6/13/16 6:22 PM

V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
1153
((4S)-2-(2-(Diphenylphosphino)phenyl)-4-isopropyl-
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4c)
s, 1 H) 2.04 (br m, 2 H, CHMe2 and e-3-HCOD), 2.31 (br
s, 1 H), 2.35 (s, 6 H, 2ꢀ-Me and 2ꢀꢀ-Me), 2.42 (br m, 2 H,
e-8-CHCOD), 3.30 (br s, 2 H, 5- and 6-HCOD), 4.15 (br s,
1 H, OCH2), 4.32 (t, J = 9.54 Hz, 1 H, OCH2), 4.43 (br s,
1 H, NCH), 4.68 (br q, J = 6.7 Hz, NOE with 2.05 ppm,
1 H, 1-CHCOD), 4.98 (br s, 1 H, 2-CHCOD), 7.21 (br s, 2 H,
6ꢀ-H), 7.37 (br s, 2 H, 3ꢀ-H), 7.43 (br s, 2 H, 4ꢀ-H), 7.58
(br s, 3 H, 3-, 4- and 5-H), 8.09 (br m, 1 H, 6-H), and the
4
Yield: 81 % (best yield found in literature is 91 % [3]).
Red crystals. Very stable on storage at r. t. even in CDCl3
solution (6 month).
((4S)-2-(2-(-Diphenylphosphino)phenyl)-4-tert-butyl-
1
signals of BARF. – 13C{ H} NMR (CDCl3, 150 MHz, r. t.,
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
assignment is not possible): δ = 12.31, 13.26, 18.71, 24.0,
27.90, 29.71, 31.17, 32.41, 21.97, 35.30, 36.16, 68.18, 70.32,
68.9, 94.6, 127.08 (d, J = 8 Hz), 129.51, 132.11, 132.46 (d,
J = 8 Hz), 132.62, 133.66, 133.71, 133.81 (d, J = 8 Hz),
135.3, 163.88, and the signals of BARF. – 31P NMR (CDCl3,
161 MHz, r. t.): 8.54 (br s, 0.9 P), 16.14 (br s, 1 P). – 1H NMR
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4d)
Yield: 79.7 %. Red crystals. Very stable on storage at r. t.
even in CDCl3 solution (6 month). – [α]2D1 = −155 (c = 0.105,
1
CHCl3). – H NMR (CDCl3, 600 MHz): δ = 0.63 (s, 9 H,
Me), 1.43(nrm, 1 H, a-4-HCOD) 1.6 (nrm, 1 H, a-8-HCOD),
2.0 (nrm, 2 H, e-4- and e-8-HCOD), 2.47 (nrm, 2 H, a-3-
and a-7-HCOD), 2.40 (nrm, 1 H, e-3-HCOD), 2.55 (nrm, 1 H,
e-7-HCOD), 3.04 (br s, 1 H, NOE with 7.11 ppm, 5-HCOD),
3.5 (br s, 1 H, NOE with 7.46 ppm, 6-HCOD), 3.94 (dd, J =
9.4 Hz, J = 2.6 Hz, NCHtBu) 4.32 (t, J = 9.4 Hz, 1 H,
OCH2), 4.58 (dd, J = 9.4 Hz, J = 2.6 Hz, 1 H, OCH2),
4.95 (br m, 2 H, 1- and 2-HCOD), 7.11 (br m, 2 H, 2ꢀ-H),
7.32 (nrm, 1 H, 3-H), 7.43 (nrm, 2 H, 3ꢀ-H), 7.46 (nrm,
2 H, 2ꢀꢀ-H), 7.49 (nrm, 1 H, 4ꢀ-H), 7.50 (nrm, 2 H, 3ꢀꢀ-H),
7.55 (nrm, 1 H, 4ꢀꢀ-H), 7.62 (nrm, 2 H, 4- and 5-H), 8.20
◦
(CDCl3, 400 MHz, −40 C): δ = −0.09 (d, J = 6.64 Hz,
1 H), 0.12 (d, J = 6.6 Hz, 1.6 H), 0.84 (d, J = 7 Hz, 1.3 H),
0.92 (d, J = 6.6 Hz, 1.8 H), 1.37 (br s, 1.2 H), 1.55 (br s,
1.3 H), 1.85 – 2.04 (br m, 4.9 H), 2.22 – 2.57 (br m, 8.6 H),
2.82 (br s, 0.4 H), 3.15 (br s, 0.4 H), 3.28 – 3.39 (br m,
1.65 H), 4.1 – 4.2 (br m, 0.9 H), 4.32 – 4.44 (br m, 1.3 H),
4.50 (br d, J = 7 Hz, 0.6 H), 4.67 (br s, 1 H), 4.93 – 5.08
(br m, 0.9 H), 6.63 (m , 0.8 H), 6.91 (m, 0.7 H), 7.07 (m,
0.7 H), 7.18 – 7.26 (m, 1.7 H), 7.34 – 7.70 (m, 12 H), 8.07
(br m, 1 H), 9.07 (m, 0.5 H), and the signals of BARF. –
1
(m, 1 H, 6-H), and the signals of BARF. – 13C{ H} NMR
1
13C{ H} NMR (CDCl3, 150 MHz, −40 ◦C): δ = 11.94,
(CDCl3, 150 MHz): δ = 25.09 (Me), 25.51 (8-CH2COD),
28.16 (4-CH2COD), 32.70 (3-CH2COD), 34.42 (CMe3), 36.8
(7-CH2COD), 62.74 (5-CHCOD), 63.37 (6-CHCOD), 69.82
(OCH2), 74.47 (NCHtBu), 93.28 (d, J = 13.8 Hz, 1-CHCOD),
97.57 (d, J = 10.3 Hz, 2-CHCOD), 122.31 (d, J = 57.4 Hz,
1ꢀ-C), 127.61 (d, J = 48.2 Hz, 2-C), 128.83 (d, J = 10.3 Hz,
3ꢀ-CH), 129.12 (d, J = 13.8 Hz, 1-C), 129.60 (d, J = 51.6 Hz,
1ꢀꢀ-C), 129.70 (d, J = 11.5 Hz, 3ꢀꢀ-CH), 132.09 (4ꢀ-CH),
132.58 (d, J = 1.6 Hz, 5-CH), 132.62 (4ꢀꢀ-CH), 133.19 (d,
J = 10.3 Hz, 2ꢀ-CH), 133.98 (d, J = 8.0 Hz, 6-CH), 134.20
(d, J = 14.9 Hz, 2ꢀꢀ-CH), 134.23 (d, J = 6.9 Hz, 4-CH),
134.93 (d, J = 2.4 Hz, 3-CH), 164.03 (d, J = 4.6 Hz, N =C),
and the signals of BARF. – 31P NMR (CDCl3, 161 MHz):
δ = +17.5. – HRMS ESI/FT-ICR: isotope cluster 686 – 690,
found (calcd.): 686.2380, 53 % (686.2297, 60 %); 687.2416,
13 % (687.2330, 21 %); 688.2323, 100 % (688.2320, 100 %);
689.2315, 44 % (689.2354, 36 %); 690.2344, 5 % (690.2387,
6 %).
13.26, 18.69, 23.45 (br s), 23.79 (d, J = 8 Hz), 24.67 (d,
J = 5.7 Hz), 25.32, 26.77 (d, J = 8 Hz), 27.36, 27.67, 29.70
(br s), 32.12, 32.24, 32.27, 33.06, 35.38 (br s), 36.23 (br
s), 64.07, 65.04, 66.42, 67.51, 67.81, 68.05, 69.66, 69.88,
88.31 (d, J = 12.6 Hz), 89.20 (br d, J = 13.8 Hz), 94.03
(d, J = 10.3 Hz), 94.76 (br d, J = 9.2 Hz), 117.51 (d, J =
57.0 Hz), 117.67, 120.39 (d, J = 53.9 Hz), 125.99, 126.31
(d, J = 4.6 Hz), 126.43, 126.77, 126.84 (d, J = 4.6 Hz),
126.99 (d, J = 6.9 Hz), 127.07 (d, J = 8.0 Hz), 127.70 (d,
J = 12.6 Hz), 127.68, 128.29 (d, J = 19.5 Hz), 129.17, 131.7 –
132.4 (m), 133.2 – 133.7 (m), 133.89, 134.38, 135.83, 140.57
(d, J = 9.2 Hz), 141.51 (d, J = 9.2 Hz), 142.60, 142.70,
140.80, 143.45, 163.16 (d, J = 4.6 Hz), 163.76 (d, J =
8.0 Hz), and the signals of BARF. – 31P NMR (CDCl3,
161 MHz, −40 ◦C): δ = 8.21 (s, 0.75 P), 15.75 (s,
1 P). – HRMS ESI/FT-ICR: isotope cluster 644 – 648,
found (calcd.): 700.2441, 51 % (700,2453, 60 %); 701.2434,
17 % (701,2487, 22 %); 702.2472, 100 % (702,2477, 100 %);
703.2477, 34 % (703,2510, 37 %); 704.2539, 6 % (703,2510,
7 %).
((4S)-2-(2-(Di(o-tolyl)phosphino)phenyl)-4-isopropyl-
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4e)
((4S)-2-(2-(Di(o-tolyl)phosphino)phenyl)-4- tert-butyl-
Yield: 85 %. Red crystals. Very stable on storage at r. t.
even in CDCl3 solution (6 month). – [α]2D0 = −97 (c = 0.13,
CHCl3). – 31P NMR (1,2,4-trichlorobenzene, 161 MHz,
140 ◦C): δ = +12.5. – 1H NMR (CDCl3, 600 MHz, r. t., full
assignment is not possible): δ = 0.05 (br s, 3 H), 0.87 (br s, Orange crystals, very stable on storage at r. t. even in CDCl3
3 H, Me), 1.41 (br s, 1 H, Me), 1.58 (br m, 1 H), 1.95 (br solution (6 month).
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4f)
Yield: 83 % (best yield found in literature is 72 % [15]).
Unauthenticated
Download Date | 6/13/16 6:22 PM

1154
V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
((4S)-2-(2-(Diphenylphosphino)phenyl)-4-isopropyl-
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
hexafluorophosphate (4j)
Yield: 78 % (best yield found in literature is 82 % [2]).
Red crystals. Unstable on storage in solution, but stable in
crystalline state, can be stored at r. t., but better at −20 ◦C.
(2-(2-(-Diphenylphosphino)phenyl)- 4,4-dimethyl-4,5-
4
dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4k)
2.01 (nrm, 1 H, e-7-HCOD), 2.12 (nrm, 1 H, e-3-HCOD),
2.42 (nrm, 1 H, a-8-HCOD), 2.49 (nrm, 1 H, a-4-HCOD),
2.52 (nrm, 1 H, e-8-HCOD), 2.63 (nrm, 1 H, e-4-HCOD),
3.03 (br s, 1 H, NOE with 7.10 ppm, 6-HCOD), 3.54 (br s,
1 H, NOE with 7.42 ppm, 5-HCOD), 4.69 (d, J = 8.5 Hz,
1 H, NCH), 5.12 (m, 1 H, NOE with 4.69 ppm, 1-HCOD),
5.16 (m, 1 H, 2-HCOD), 6.17 (d, J = 8.5 Hz, 1 H, OCH),
7.03 (d, J = 7.6 Hz, 1 H, 2ꢀꢀꢀ-H), 7.10 (dd, J = 11.5 Hz, J =
7.6 Hz, 2 H, 2ꢀꢀ-H), 7.24 (br d, J = 8.2 Hz, 1 H, 3-H), 7.28
(m, 1 H, 4ꢀꢀꢀ-H), 7.37 (t, J = 7.6 Hz, 1 H, 3ꢀꢀꢀ-H), 7.38 (nrm,
1 H, 4ꢀ-H), 7.42 (nrm, 5 H, 2ꢀ-, 6ꢀ- and 3ꢀꢀ- and 4ꢀꢀ-H), 7.47
(m, 3 H, 3ꢀ-, 5ꢀ- and 5ꢀꢀꢀ-H), 7.56 (t, J = 7.6 Hz, 1 H, 4-H),
7.61 (t, J = 7.6 Hz, 1 H, 5-H), 8.31 (ddd, J = 8.2 Hz, J =
4.1 Hz, J = 1.1 Hz, 1 H, 6-H), and the signals of BARF. –
Yield: 68 %. Red crystals. Very unstable even in crys-
talline state. Should be stored at −20 ◦C. – 1H NMR (CDCl3,
600 MHz): δ = 1.31 (s, 6 H, Me), 1.82 (nrm, 2 H, a-3- and
a-7-HCOD), 2.01 (nrm, 2 H, e-3- and e-7-HCOD), 2.22 (nrm,
4 H, 4- and 8-HCOD), 3.27 (br s, 2 H, 5- and 6-HCOD), 3.87
(s, 2 H, OCH2), 5.40 (br s, 2 H, 1- and 2-HCOD), 7.31 (br
s, 4 H, 2ꢀꢀ- and 3ꢀꢀ-H), 7.44 (nmr, 1 H, 3-H), 7.48 (nrm, 3 H,
2ꢀ- and 4ꢀꢀ-H), 7.54 (br s, 5 H, 4ꢀ-H and 4-HBARF), 7.59
(nrm, 3 H, 5- and 3ꢀ-H), 7.60 (nrm, 1 H, 4-H), 7.84 (m, 1 H,
1
6-H), and the signals of BARF. – 13C{ H} NMR (CDCl3,
150 MHz): δ = 27.81 (Me), 29.70 (br s, 4- and 8-CH2COD),
31.90 (br s, 3- and 7-CH2COD), 61.72 (5- and 6-CHCOD),
73.12 (OCH2), 82.47 (NCMe2), 93.64 (d, J = 13.2 Hz, 1-
and 2-CHCOD), 125.29 (d, J = 41.7 Hz, 2-C), 125.74 (d,
J = 60.4 Hz, 1ꢀ-C), 129.52 (4ꢀꢀ-CH), 129.28 (d, J = 11.0 Hz,
2ꢀꢀ-CH), 129.91 (d, J = 62.6 Hz, 1ꢀꢀ-C), 131.23 (d, J = 5.5 Hz,
1-C), 131.71 (br s, 3-CH), 131.90 (d, J = 7.7 Hz, 6-CH),
131.99 (5-CH), 132.53 (4ꢀ-CH), 133.39 (d, J = 6.6 Hz, 3C,
4-CH and 3ꢀ-CH), 134.07 (br s, 4C, 2ꢀ- and 3ꢀꢀ-CH), 165.49
(d, J = 7.8 Hz, N =C), and the signals of BARF. – 31P NMR
(CDCl3, 161 MHz): δ = +21.8. – HRMS ESI/FT-ICR:
isotope cluster 658 – 662, found (calcd.): 658.1974, 51 %
(658.1984, 60 %); 659.2018, 17 % (659.2017, 20 %);
660.2012, 100 % (660.2007, 100 %); 661.2029, 32 %
(661.2041, 34 %); 662.2083, 2 % (662.2074, 5 %).
1
13C{ H} NMR (CDCl3, 150 MHz): δ = 26.8 (Me), 31.2
(Me), 25.7 (d, J = 2.3 Hz, 3-CH2COD), 28.1 (7-CH2COD),
32.5 (8-CH2COD), 36.2 (4-CH2COD), 49.5 (CMe2), 62.9
(5-CHCOD), 63.9 (6-CHCOD), 79.09 (NCH), 87.8 (OCH),
91.2 (d, J = 13.7 Hz, 2-CHCOD), 96.8 (d, J = 10.0 Hz,
1-CHCOD), 123.00 (d, J = 58.5 Hz, 1ꢀꢀ-C), 123.12 (2ꢀꢀꢀ-CH),
126.30 (5ꢀꢀꢀ-CH), 127.59 (d, J = 48.2 Hz, 2-C), 128.51
(4ꢀꢀꢀ-CH), 128.77 (2ꢀ- and 6-ꢀCH), 128.99 (d, J = 51.6 Hz,
1ꢀ-C), 129.58 (d, J = 13.8 Hz, 1-C), 129.64 (d, J = 11.5 Hz,
3ꢀꢀ-CH), 131.82 (3ꢀꢀꢀ-CH), 132.10 (d, J = 2.3 Hz, 5ꢀ-CH),
132.44 (d, J = 2.3 Hz, 3ꢀ-CH), 132.52 (d, J = 2.3 Hz, 5-CH),
133.21 (d, J = 10.3 Hz, 2ꢀꢀ-CH), 133.23 (6ꢀꢀꢀ-CH), 133.94 (d,
J = 11.5 Hz, 6-CH), 133.99 (4ꢀ-CH), 134.05 (4ꢀꢀ-CH), 134.11
(d, J = 6.9 Hz, 4-CH), 135.35 (s, 3-CH), 150.87 (1ꢀꢀꢀ-CH),
163.97 (d, J = 5.7 Hz, C =N), and the signals of BARF. –
31P NMR (CDCl3, 161 MHz): δ = +16.5. – HRMS ESI/FT-
ICR: isotope cluster 746 – 750, found (calcd.): 746.2302,
54 % (746.2297, 60 %); 747.2313, 22 % (747.2330, 25 %);
748.2293, 100 % (748.2320, 100 %); 749.2287, 43 %
(749.2354, 41 %); 750.2255, 9 % (750.2387, 8 %).
((3aR,8bS)-2-(2-(Diphenylphosphino)phenyl)-4,4-
dimethyl-4,8b-dihydro-3aH-indeno[2,1-d]oxazole)-(η -1,5-
cyclooctadiene)iridium(I) tetrakis(3,5-bis(trifluoromethyl)-
4
phenyl)borate (4h)
Diphenylphosphine (61 mg, 0.33 mmol) was dissolved in
diethyl ether (1 mL), and n-BuLi (1.6 M solution in hexane,
0.21 mL, 0.33 mmol) was added in order to generate lithium
diphenylphosphide. Then 2h (84 mg, 0.3 mmol) was added.
After stirring overnight the generated ligand was allowed to
react with [Ir(COD)Cl]2 and NaBARF as described in the
general procedure A.
General procedure B for the synthesis of 4g, 4i and 4l
A two-necked 10 mL flask was charged with liquid di-
Yield: 79.6 %. Red crystals. Very stable on storage at r. t. cyclohexylphosphine (1i, 65 mg, 0.33 mmol) or solid dixy-
even in CDCl3 solution (6 month). – [α]2D1 = 0 (c = 0.105, lylphosphine (1g, 80 mg, 0.33 mmol) as described in gen-
CHCl3), [α]21 = +156 (c = 0.105, CHCl3). – 1H NMR eral procedure A. Abs. MTBE (4 mL) was added, and the
(CDCl3, 6005M46Hz, r. t.): δ = 0.76 (s, 3 H, Me), 1.41 (s, 3 H, diarylphosphine was dissolved. n-BuLi (1.6 M solution in
Me), 1.47 (nrm, 1 H, a-7-HCOD), 1.72 (nrm, 1 H, a-3-HCOD), hexane, 0.21 mL, 0.33 mmol) was added at r. t., and the
Unauthenticated
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
1155
yellow (for 1g) or colorless (for 1i) mixture was stirred 28 % (729.2800, 23 %); 730.2783, 100 % (730.2790, 100 %);
for 30 min. Liquid oxazoline 2c (62 mg, 0.3 mmol) was 731.2773, 36 % (731.2823, 39 %); 732.2912, 5 % (732.2857,
added to the reaction mixture. The mixture was refluxed 7 %).
for 12 h and cooled. At this point gas chromatography
with mass-sensitive analyzer showed a conversion of 2c of
over 80 % into the ligand 3. The mixture was evaporated in
a stream of nitrogen. [Ir(COD)Cl]2 (100.8 mg, 0.15 mmol)
and CH2Cl2 (3 mL) were added to the residue, and the mix-
ture was refluxed for 4 h. After cooling the anion exchange
(to BARF or PF6) was performed according to the general
procedure A.
((4S)-2-(2-(Dicyclohexylphosphino)phenyl)-4-isopropyl-
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4i)
4
Yield: 70 %. This complex was catalytically active in
stilbene hydrogenation, but contaminated with dicyclo-
hexylphosphine oxide, and the contaminant could not be re-
moved even by gradient column chromatography (hexane-
dichloromethane). The synthesis of analytically pure 4i is de-
scribed below.
((4S)-2-(2-(Bis(2,6-dimethylphenyl)phosphino)phenyl)-4-
4
isopropyl-4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iri-
dium(I) tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4g)
((4S)-2-(2-(Dicyclohexylphosphino)phenyl)-4-isopropyl-
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
hexafluorophosphate (4l)
Yield: 66.9 %. This complex was catalytically active in
stilbene hydrogenation, but impure. It could not be pu-
rified even by gradient column chromatography (hexane-
dichloromethane). Yellow crystals, unstable even in crys-
4
Yield: 68 %. Red crystals. Very unstable on storage
talline state. Should be stored at −20 ◦C. – [α]D21 = −19 (c = even as◦crystals at r. t. (stable for 1 d). Should be stored
1
1
0.12, CHCl3), [α]25416 = −48 (c = 0.12, CHCl3). – H NMR at −20 C. – [α]1D9 = −136 (c = 0.11, CHCl3). – H NMR
(CDCl3, 600 MHz, r. t.): δ = 0.48 (d, J = 6.7 Hz, 3 H, (CDCl3, 600 MHz, r. t.): δ = 0.80 (d, J = 6.6 Hz, 3 H, Me),
MeiPr), 1.01 (d, J = 6.7 Hz, 3 H, MeiPr), 1.85 (s, 3 H, 1.08 (d, J = 6.9 Hz, 3 H, Me), 1.15 – 1.4 (nrm, 8 H, Cy),
6ꢀꢀ-Me), 2.00 (s, 3 H, 2ꢀꢀ-Me), 2.22 (s, 3 H, 2ꢀ-Me), 2.50 1.4 – 1.5 (nrm, 2 H, Cy), 1.70 – 1.95 (nrm, 10 H, Cy), 1.61
(m, 1 H, CHMe2), 3.19 (m, 1 H, 5-HCOD), 3.29 (m, 1 H, (nrm, 1 H, a-4-HCOD), 1.66 (nrm, 1 H, a-8-HCOD), 2.07 (nrm,
6-HCOD), 4.40 (br d, J = 8.1 Hz, 2 H, OCH2), 4.63 (br 2 H, CHMe2 and e-8-HCOD), 2.13 (nrm, 2 H, e-4-HCOD and
td, J = 8.1 Hz, J = 2.5 Hz, 1 H, NCH), 4.70 (m, NOE 1ꢀ-H), 2.29 (nrm, 1 H, a-3-HCOD), 2.49 (nrm, 4 H, e-3-HCOD
,
with 3.29 ppm, with 1.76 ppm, 1 H, 2-HCOD), 5.24 (m, 7-HCOD and 1ꢀꢀ-H), 3.69 (br s, 1 H, 5-HCOD), 4.15 (br s,
1 H, NOE with 2.5 ppm, 4.63 ppm, 1-HCOD), 6.86 (br 1 H, 6-HCOD), 4.32 (m, 1 H, NCH), 4.62 (d, J = 5.9 Hz,
s, 1 H, 4ꢀ-H), 7.05 (nrm, 2 H, 3ꢀ- and 5ꢀ-H), 7.15 (nrm, 2 H, OCH2), 4.74 (m, NOE with 2.07, 4.32 and 4.62 ppm,
2 H, 3ꢀꢀ- and 5ꢀꢀ-H), 7.37 (nrm, 1 H, 4ꢀꢀ-H), 7.55 (t, J = 1 H, 1-HCOD), 5.13 (br s, NOE with 4.32 and 4.62 ppm, 1 H,
7.5 Hz, 1 H, 5-H), 7.66 (t, J = 7.5 Hz, 1 H, 4-H), 8.05 2-HCOD), 7.67 (pseudo-t, J = 7.8 Hz, 1 H, 5-H), 7.78 (m, 2 H,
(dd, J = 10.3 Hz, J = 7.5 Hz, 1 H, 3-H), 8.27 (t, J = 3- and 4-H), 8.31 (dd, J = 7.9 Hz, J = 2.9 Hz, 1 H, 6-H). –
1
7.5 Hz, 1 H, 6-H), and the signals of BARF, CH2COD and 13C{ H} NMR (CDCl3, 150 MHz): δ = 14.84 (Me), 19.26
6ꢀ-Me are not distinguishable, since the compound is not (Me), 25.87 (Cy), 26.03 (Cy), 26.09 (8-CH2COD), 26.94 (d,
1
pure. – 13C{ H} NMR (CDCl3, 150 MHz): δ = 7.53 (6ꢀ- J = 8.0 Hz, Cy), 27.02 (d, J = 9.2 Hz, Cy), 27.13 (d, J =
Me), 13.78 (MeiPr), 19.01 (MeiPr), 22.78 (2C, 2ꢀ-Me and 11.5 Hz, Cy), 27.32 (d, J = 9.2 Hz, Cy), 28.12 (d, J = 3.4 Hz,
2ꢀꢀ-Me), 26.73 (6ꢀꢀ-Me), 29.94 (CHMe2), 44.66 (6-CHCOD), Cy), 29.11 (Cy), 29.44 (4-CH2COD), 29.98 (Cy), 30.65 (Cy),
66.90 (5-CHCOD), 67.04 (OCH2), 79.38 (d, J = 23.8 Hz, 31.65 (3-CH2COD), 32.09 (d, J = 27.5 Hz, 1ꢀꢀ-CH), 32.96
1-CHCOD), 81.75 (NCH), 103.05 (s, 2-CHCOD), 123.42 (d, (CHMe2), 36.15 (7-CH2COD), 41.95 (d, J = 26.4 Hz, 1ꢀ-CH),
J = 16.5 Hz, 3ꢀ-CH), 126.00 (d, J = 12.8 Hz, 1-C), 126.28 59.86 (5-CHCOD), 61.92 (6-CHCOD), 68.20 (OCH2), 70.19
(d, J = 56.82 Hz, 1ꢀꢀ-C), 129.76 (d, J = 47.7 Hz, 2-C), 130.32 (NCH), 89.90 (d, J = 11.5 Hz, 1-CHCOD), 95.46 (d, J =
(d, J = 7.3 Hz, 4ꢀ-CH), 130.51 (d, J = 88.0 Hz, 1ꢀ-C), 130.74 11.5 Hz, 2-CHCOD), 126.80 (d, J = 35.6 Hz, 2-C), 129.45
(d, J = 7.3 Hz, 3ꢀꢀ-CH), 130.76 (d, J = 12.8 Hz, 6ꢀ-CMe), (d, J = 9.2 Hz, 1-C), 131.74 (d, J = 2.3 Hz, 5-CH), 132.43 (d,
131.14 (d, J = 7.3 Hz, 5ꢀꢀ-CH), 131.48 (s, 4ꢀꢀ-CH), 131.68 J = 1.2 Hz, 3-CH), 133.87 (d, J = 5.7 Hz, 4-CH), 134.07 (d,
(s, 5ꢀ-CH), 131.82 (5-CH), 131.98 (d, J = 7.3 Hz, 4-CH), J = 8.0 Hz, 6-CH), 164.34 (d, J = 5.7 Hz, N =C). – 31P NMR
134.85 (d, J = 7.3 Hz, 6-CH), 135.53 (s, 3-CH), 140.35 (d, (CDCl3, 161 MHz): δ = +10.1 (ligand), −143.7 (sep, J =
J = 9.2 Hz, 2ꢀꢀ-CMe), 141.27 (d, J = 9.2 Hz, 6ꢀꢀ-CMe), 141.45 714 Hz, PF6). – 19F NMR (CDCl3, 376 MHz): δ = −73.6 (d,
(d, J = 1.6 Hz, 2ꢀ-CMe), 163.8 (d, J = 5.5 Hz, N =C), and J = 714 Hz). – HRMS ESI/FT-ICR: isotope cluster 684 – 688,
the signals of BARF, CH2COD are not distinguishable, since found (calcd.): 684.3051, 54 % (684.3079, 60 %); 685.3070,
the compound is not pure. – 31P NMR (CDCl3, 161 MHz): 17 % (685.3113, 21 %); 686.3089, 100 % (686.3103, 100 %);
δ = +20.8. – HRMS ESI/FT-ICR: isotope cluster 728 – 732, 687.3071, 33 % (687.3136, 35 %); 688.3137, 5 % (688.3170,
found (calcd.): 728.2704, 78 % (728.2766, 60 %); 729.2763, 6 %).
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1156
V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
((4S)-2-(2-(Dicyclohexylphosphino)phenyl)-4-isopropyl-
4
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)iridium(I)
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (4i) from 4l
4l (50 mg, 0.06 mmol) and NaBARF (54 mg, 0.061 mmol)
were dissolved in CH2Cl2 (5 mL). The anion exchange was
monitored by TLC on silica gel eluting with CH2Cl2. Rf of 4l
is 0, that of 4i is 0.9. Within 2 h the mixture was adsorbed on
silica gel and chromatographed on silica gel (10 g) according
to the general procedure A. Yield: 71 %. Red crystals. Stable
on storage in crystalline form at r. t. for at least 1 week. Nev-
◦
ertheless, it should be stored at −20 C. – [α]1D9 = −48 (c =
0.135, CHCl3). – 1H NMR (CDCl3, 600 MHz, r. t.): δ = 0.77 Aldrich, 0.64 mL, 0.32 mmol) was added at r. t. The mix-
(d, J = 6.4 Hz, 3 H, Me), 1.00 (d, J = 7.0 Hz, 3 H, Me), ture was stirred overnight at r. t. Degassed water (a few
1.19 – 1.35 (nrm, 8 H, Cy), 1.37 – 1.50 (nrm, 2 H, Cy), 1.66 – drops) was added, and all volatiles (including diphenylphos-
1.93 (nrm, 10 H, Cy), 1.61 (nrm, 2 H, a-4- and a-8-HCOD), phine) were removed in vacuo (10−2 mbar) with heating
2.01 (nrm, 1 H, e-8-HCOD), 2.07 (m, 1 H, CHMe2), 2.14 (60 ◦C). The residue was redissolved in abs. CH2Cl2 (5 mL).
(nrm, 1 H, e-4-HCOD), 2.07 (nrm, 1 H, a-7-HCOD), 2.22
A
31P NMR spectrum of this solution showed one signal
(nrm, 1 H, 1ꢀ-H), 2.23 (nrm, 1 H, a-3-HCOD), 2.38 (nmr, at δ = −6 ppm (consistent with ref. [29]). [Ir(COD)Cl]2
1 H, e-3-HCOD), 2.46 (nrm, 1 H, e-7-HCOD), 2.47 (nrm, (50 mg, 0.0744 mmol) was added to this solution, which
1 H, 1ꢀꢀ-H), 3.72 (br s, 5-CHCOD), 4.16 (dt, J = 8.8 Hz, was stirred at r. t. for 2 h (refluxing leads to decomposition
J = 2.9 Hz, 1 H, NCH), 4.19 (br s, 1 H, 6-CHCOD), 4.32 of the target complex). A 31P NMR spectrum of this solu-
(t, J = 9.4 Hz, 1 H, OCH2), 4.55 (dd, J = 9.4 Hz, J = 2.9 Hz, tion showed one singlet at δ = +20 ppm. From this point
1 H, OCH2), 4.66 (m, NOE with 4.16, 2.07, 0.77 ppm, 1 H, work was continued in air. NaBARF (135 mg, 0.152 mmol)
1-HCOD), 4.86 (br s, NOE with 4.16 ppm, 1 H, 2-HCOD), was added, and the mixture was stirred for 2 h. The mix-
7.55 (m, 1 H, 5-H), 7.66 (t, J = 7.6 Hz, 1 H, 4-H), 7.74 (br ture was adsorbed on 1 g of silica gel, and column chro-
s and d, J = 8.8 Hz, 9 H, 2-HBARF and 3-H), 8.21 (dd, J = matography was performed on 20 g of silica gel according
10.6 Hz, J = 2.4 Hz, 1 H, 6-H), and the signals of BARF. – to the general procedure A with the mixture CH2Cl2-hexane
1
13C{ H} NMR (CDCl3, 150 MHz): δ = 14.53 (Me), 19.16 (2 : 1). The first spot represented some by-products, whereas
(Me), 25.76 (Cy), 26.00 (2C, Cy and 8-CH2COD), 26.91 (d, the more polar second spot represented the title compound.
J = 9.2 Hz, Cy), 26.99 (d, J = 9.2 Hz, Cy), 27.12 (d, J = Yield: 34 %. Red crystals. Very unstable even in crystalline
◦
11.5 Hz, Cy), 27.37 (d, J = 10.3 Hz, Cy), 28.23 (d, J = 2.3 Hz, state at r. t., should be stored at −20 C or below. In CDCl3
Cy), 29.18 (Cy), 29.43 (4-CH2COD), 30.18 (Cy), 30.68 (Cy), solution, decomposition begins within 1 h. – [α]2D5 = −113
31.57 (3-CH2COD), 32.20 (d, J = 28.7 Hz, 1ꢀꢀ-C), 32.87 (c = 0.11, CHCl3). – 1H NMR (CDCl3, 600 MHz, r. t.): δ =
(CHMe2), 36.04 (d, J = 3.5 Hz, 7-CH2COD), 42.18 (d, J = 1.44 (nrm, 1 H, a-4-HCOD), 1.57 (nrm, 1 H, a-8-HCOD), 2.01
27.5 Hz, 1ꢀ-C), 60.82 (5-CHCOD), 62.92 (6-CHCOD), 67.87 (nrm, 1 H, e-8-HCOD), 2.05 (nrm, 1 H, e-4-HCOD), 2.41 (nrm,
(OCH2), 70.27 (NCH), 89.43 (d, J = 13.8 Hz, 1-CHCOD), 1 H, a-7-HCOD), 2.47 (nrm, 1 H, a-3-HCOD), 2.52 (nrm, 1 H,
94.14 (d, J = 10.3 Hz, 2-CHCOD), 127.04 (d, J = 35.6 Hz, e-3-HCOD), 2.53 (nrm, 1 H, e-7-HCOD), 3.21 (s, 1 H, NOE
2-C), 129.16 (d, J = 11.5 Hz, 1-C), 131.84 (5-CH), 132.38 with 7.14 ppm, 5-HCOD), 3.38 (s, 1 H, 6-HCOD), 3.72 (m,
(s, 3-CH), 134.03 (d, J = 6.9 Hz, 6-CH), 133.94 (d, J = 2 H, OCH2), 4.13 (m, 1 H, NCH), 4.68 (br s, 1 H, 2-HCOD),
5.7 Hz, 4-CH), 164.4 (d, J = 5.8 Hz, N =C), and the 4.82 (s, 1 H, NOE with 4.13 ppm, 1-HCOD), 5.68 (d, J =
signals of BARF. – 31P NMR (CDCl3, 161 MHz): δ = 3.5 Hz, CHOH), 7.14 (br s, 2 H, 2ꢀ-H), 7.26 (s under sig-
+10.4. – HRMS ESI/FT-ICR: isotope cluster 684 – 688, nal of CHCl3, 2ꢀꢀꢀ-H), 7.44 (nrm, 1 H, 3-H), 7.46 (nrm, 1 H,
found (calcd.): 684.3045, 54 % (684.3079, 60 %); 685.3143, 4ꢀꢀꢀ-H), 7.47 (nrm, 3 H, 4ꢀ- and 3ꢀꢀꢀ-H), 7.49 (nrm, 2 H, 3ꢀ-H),
19 % (685.3113, 21 %); 686.3098, 100 % (686.3103, 100 %); 7.57 (nrm, 1 H, 4ꢀꢀ-H), 7.58 (nrm, 2 H, 3ꢀꢀ-H), 7.65 (nrm,
687.3043, 34 % (687.3136, 35 %); 688.3145, 8 % (688.3170, 2 H, 2ꢀꢀ-H), 7.66 (nrm, 1 H, 4-H), 7.70 (nrm, 1 H, 5-H), 8.31
6 %).
(m, 1 H, 6-H), and the signals of BARF, OH-exchanged. –
1
13C{ H} NMR (CDCl3, 150 MHz): δ = 26.37 (8-CH2COD),
(1S)-((4S)-2-(2-(Diphenylphosphino)phenyl)-4,5-dihydro-
oxazol-4-yl)(phenyl)methanol-(η -1,5-cyclooctadiene)-
iridium(I) tetrakis(3,5-bis(trifluoromethyl)phenyl)borate
28.52 (4-CH2COD), 32.24 (7-CH2COD), 36.15 (3-CH2COD),
64.12 (5-CHCOD), 64.42 (6-CHCOD), 64.54 (OCH2), 74.27
(NCH), 83.33 (CHOH), 93.76 (d, J = 13.8 Hz, 1-CHCOD),
97.08 (d, J = 11.5 Hz, 2-CHCOD), 121.20 (d, J = 58.5 Hz,
1ꢀ-C), 124.85 (2ꢀꢀꢀ-CH), 128.51 (d, J = 48.2 Hz, 2-C), 128.63
(d, J = 12.6 Hz, 1-C), 129.15 (d, J = 11.5 Hz, 3ꢀ-CH), 129.75
4
(4m)
2m (41.3 mg, 0.152 mmol) was dissolved in 5 mL of
abs. Et2O. To this solution KPPh2 (0.5 N solution in THF,
Unauthenticated
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
1157
(3ꢀꢀꢀ-CH), 129.82 (d, J = 53.9 Hz, 1ꢀꢀ-C), 130.04 (3ꢀꢀ-CH), cis-Bis-((4S)-2-(2-(diphenylphosphino)phenyl)-4-isopropyl-
130.18 (4ꢀꢀꢀ-CH), 130.40 (4ꢀ-CH), 132.46 (4ꢀꢀ-CH), 132.59 4,5-dihydrooxazole)rhodium(I) tetrakis(3,5-bis(trifluoro-
(5-CH), 132.99 (d, J = 14.5 Hz, 2ꢀ-CH), 133.84 (s, 3-CH), methyl)phenyl)borate (6)
133.86 (d, J = 8.0 Hz, 6-CH), 134.41 (d, J = 12.6 Hz, 3C, 4-
Synthesized from 2c (84 mg, 0.405 mmol), 1a
and 2ꢀꢀ-CH), 136.93 (1ꢀꢀꢀ-C), 164.67 (d, J = 5.7 Hz, N =C),
(84 mg, 0.451 mmol), n-BuLi (0.28 mL, 0.451 mmol),
and the signals of BARF. – 31P NMR (CDCl3, 161 MHz):
[Rh(COD)Cl]2 (40 mg, 0.081 mmol), and NaBARF (144 mg,
δ = +16.9. – HRMS ESI/FT-ICR: isotope cluster 736 – 740,
0.162 mmol) according the general procedure A. After an-
found (calcd.): 736.2111, 54 % (736.2090, 60 %); 737.2136,
ion exchange the mixture was adsorbed on silica gel and
23 % (737.2123, 23 %); 738.2131, 100 % (738.2113, 100 %);
the solvents evaporated. The column (20 g of silica gel) was
739.2160, 36 % (739.2146, 39 %), 740.2230, 5 % (740.2180,
packed with silica with the adsorbed complex placed on top.
7 %).
The column was first eluted with ca. 100 mL of hexane in
order to remove cyclooctadiene, then with CH2Cl2. Yield:
((4S)-2-(2-(Diphenylphosphino)phenyl)-4-isopropyl-
4,5-dihydrooxazole)-(η -1,5-cyclooctadiene)rhodium(I)
4
81.6 %; brown crystals, unstable at r. t. even in crystalline
form, should be stored at −20 ◦C. – [α]D21 = −687 (c = 0.115,
tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (5)
CHCl3). – 1H NMR (CDCl3, 600 MHz, r. t.): δ = 0.44 (d,
According to the general procedure A, with
[Rh(COD)Cl]2. Yield: 86 %. Yellow crystals. Stable in
J = 6.8 Hz, 3 H, Me), 1.09 (d, J = 6.8 Hz, 3 H, Me), 2.09
(m, CHMe2), 3.85 (m, 1 H, NCH), 4.39 (m, 2 H, OCH2),
6.87 (br s, 4 H, 2ꢀ- and 3-ꢀH), 6.96 (br m, 1 H, 3-H), 7.12
(t, J = 7.5 Hz, 1 H, 4ꢀ-H), 7.33 (t, J = 7.5 Hz, 2 H, 3ꢀꢀ-H),
7.42 (nrm, 1 H, 4ꢀꢀ-H), 7.45 (nrm, 1 H, 4-H), 7.49 (nrm,
1 H, 5-H), 7.53 (nrm, 2 H, 2ꢀꢀ-H), 7.96 (br d, J = 7.5 Hz,
◦
CDCl3 solution at −20 C for at least 2 weeks. Should be
◦
stored at −20 C in crystalline form. – [α]2D1 = −41 (c =
0.11, CHCl3). – 1H NMR (CDCl3, 600 MHz, r. t.): δ =
−0.15 (d, J = 6.6 Hz, 3 H, Me), 0.80 (d, J = 7.0 Hz, 3 H,
Me), 1.85 (nrm, 1 H, a-4-HCOD), 1.95 (nrm, 2 H, CHMe2
and a-8-HCOD), 2.13 (nrm, 1 H, e-4-HCOD), 2.19 (nrm, 1 H,
e-8-HCOD), 2.45 (nrm, 1 H, a-3-HCOD), 2.50 (nrm, 1 H,
a-7-HCOD), 2.69 (nrm, 1 H, e-3-HCOD), 2.79 (nrm, 1 H,
e-7-HCOD), 3.51 (br s, NOE with 7.05 ppm, 1 H, 5-HCOD),
3.59 (br s, NOE with 7.05, 7.68 ppm, 1 H, 6-HCOD), 3.79 (br
d, J = 8.7 Hz, 1 H, NCH), 4.29 (t, J = 9.4 Hz, 1 H, OCH2),
4.33 (dd, J = 9.4 Hz, J = 3.5 Hz, 1 H, OCH2), 5.27 (br s,
2 H, 1- and 2-HCOD), 7.05 (nrm, 2 H, 2ꢀ-H), 7.33 (br dd, J =
9.0 Hz, J = 7.0 Hz, 1 H, 3-H), 7.41 (t, J = 7.2 Hz, 2 H, 3ꢀ-H),
7.50 (br s, 3 H, 4ꢀ- and 3ꢀꢀ-H), 7.56 (nrm, 1 H, 4ꢀꢀ-H), 7.61
(nrm, 2 H, 4- and 5-H), 7.68 (nrm, 2 H, 2ꢀꢀ-H), 8.09 (m, 1 H,
1
6-H), and the signals of BARF. – 13C{ H} NMR (CDCl3,
150 MHz): δ = 16.06 (Me), 20.69 (Me), 32.46 (CHMe2),
69.25 (OCH2), 73.47 (NCH), 127.97 (br s, 3ꢀ-CH), 128.11
(t, J = 6.9 Hz, 1-C), 128.34 (t, J = 4.6 Hz, 3ꢀꢀ-CH), 129.69
(4ꢀ-CH), 130.41 (5-CH), 130.76 (t, J = 20.7 Hz, 1ꢀꢀ-C),
131.18 (4ꢀꢀ-CH), 131.41 (br s, 6-CH), 132.52 (br s, 2ꢀ-CH),
132.71 (s, 3-CH), 132.92 (br s, 4-CH), 134.43 (dd, J =
20.7 Hz, J = 17.2 Hz, 2-C), 134.72 (t, J = 5.7 Hz, 2ꢀꢀ-CH),
163.63 (s, N =C), and the signals of BARF, 1ꢀ-C is not identi-
fied, since the broad signal at 6.87 ppm shows no cross peaks
in an HMBC spectrum. – 31P NMR (CDCl3, 161 MHz): δ =
+49.3 (d, J = 174.8 Hz). – HRMS ESI/FT-ICR: isotope clus-
ter 849 – 852, found (calcd.): 849.2263, 100 % (849.2246,
100 %); 850.2285, 49 % (850.2280, 52 %); 851.2387, 10 %
(851.2313, 13 %).
6-H), and the signals of BARF. – 13C{ H} NMR (CDCl3,
1
150 MHz): δ = 12.29 (Me), 18.79 (Me), 26.33 (8-CH2COD),
28.65 (4-CH2COD), 30.70 (3-CH2COD), 32.44 (CHMe2),
35.33 (7-CH2COD), 67.74 (OCH2), 70.90 (NCH), 77.61 (d,
J = 11.5 Hz, 6-CHCOD), 79.05 (d, J = 12.6 Hz, 5-CHCOD),
105.52 (dd, J = 11.5 Hz, J = 8.0 Hz, 1-CHCOD), 107.66 (dd,
J = 9.2 Hz, J = 6.9 Hz, 2-CHCOD), 117.45 (br s, 4ꢀꢀ-CH),
124.33 (d, J = 49.3 Hz, 1ꢀ-C), 128.52 (d, J = 40.2 Hz, 2-C),
128.54 (d, J = 14.9 Hz, 1-C), 129.03 (d, J = 10.3 Hz, 3ꢀ-CH),
129.13 (1ꢀꢀ-C), 129.80 (d, J = 10.3 Hz, 3ꢀꢀ-CH), 131.81 (d,
J = 2.3 Hz, 4ꢀ-CH), 132.20 (d, J = 2.3 Hz, 5-CH), 132.64 (d,
J = 2.3 Hz, 4-CH), 132.86 (d, J = 10.3 Hz, 2ꢀ-CH), 133.64
(d, J = 8.0 Hz, 6-CH), 133.72 (d, J = 13.8 Hz, 3-CH), 134.46
(d, J = 12.6 Hz, 2ꢀꢀ-CH), 163.81 (d, J = 8.0 Hz, N =C), and
the signals of BARF. – 31P NMR (CDCl3, 161 MHz): δ =
+30.7 (d, J = 154.1 Hz). – HRMS ESI/FT-ICR: isotope clus-
ter 584 – 586, found (calcd.): 584.1588, 100 % (584.1590,
100 %); 585.1596, 32 % (585.1623, 35 %); 586.1613, 5 %
(586.1657, 6 %).
Acknowledgements
V. S. thanks the Herbert-Quandt foundation and the Ger-
man Academic Exchange Service (DAAD) for a doctoral fel-
lowships and the partnership program between the University
of Konstanz and the NTSU Kyiv for having the opportunity
to perform his doctoral studies in Konstanz. We are grate-
ful to Anke Friemel, Ulrich Haunz, Reinhold Weber and to
Dmitry Galetskiy (University of Konstanz) for measuring of
NMR and mass spectra, and to Milena Quentin for helping
to prepare the manuscript, and to Umicore, MCAT, Bayer
AG, Merck KGaA and Wacker AG for generous gifts of
reagents.
Unauthenticated
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V. Semeniuchenko et al. · (Phosphinodihydrooxazole) (1,5-cyclooctadiene) Iridium Complexes
[1] A. Lightfoot, P. Schnider, A. Pfaltz, Angew. Chem., Int.
[16] C. Y. Legault, A. B. Charette, J. Am. Chem. Soc. 2005,
127, 8966 – 8967.
[17] E. C. Ashby, R. Gurumurthy, R. W. Ridlehuber, J. Org.
Chem. 1993, 58, 5832 – 5837.
[18] N. V. Ushakov, V. M. Vdovin, M. V. Pozdnyakova,
N. A. Pritula, Russ. Chem. Bull. 1983, 32, 1920 – 1923.
[19] A. Y. Garner, A. A. Tedeschi, J. Am. Chem. Soc. 1962,
84, 4734 – 4737.
Ed., Engl. 1998, 37, 2897 – 2899; Angew. Chem. 1998,
110, 3047 – 3050.
[2] P. Schnider, G. Koch, R. Pretot, G. Wang, F. M.
Bohnen, C. Kru¨ger, A. Pfaltz, Chem. Eur. J. 1997, 3,
887 – 892.
[3] S. Kainz, A. Brinkmann, W. Leitner, A. Pfaltz, J. Am.
Chem. Soc. 1999, 121, 6421 – 6429.
[4] M. Solinas, P. Wasserscheid, W. Leitner, A. Pfaltz,
Chem. Ing. Tech. 2003, 75, 1153.
[5] V. Semeniuchenko, V. Khilya, U. Groth, Synlett 2009,
271 – 275.
[6] A. M. Aguiar, H. J. Greenberg, K. E. Rubenstein,
J. Org. Chem. 1963, 28, 2091 – 2093.
[20] A. J. Kirby, S. G. Warren, The organic chemistry of
phosphorus, Elsevier, Amsterdam 1967.
[21] J. A. S. Howell, N. Fey, J. D. Lovatt, P. C. Yates,
P. McArdle, D. Cunningham, E. Sadeh, H. E. Gottlieb,
Z. Goldschmidt, M. B. Hursthouse, M. E. Light, Dalton
Trans. 1999, 3015 – 3028.
[7] M. Peer, J. C. De Jong, M. Kiefer, T. Langer, H. Rieck,
H. Schell, P. Sennhenn, J. Sprinz, H. Steinhagen,
B. Wiese, G. Helmchen, Tetrahedron 1996, 52, 7547 –
7583.
[22] R. H. Crabtree in The Handbook of Homogeneous Hy-
drogenation, Vol. 1 (Eds.: J. G. de Vries, C. J. Elsevier),
Wiley-VCH, Weinhein 2007, chapter 2, pp. 31 – 44.
[23] R. H. Crabtree, H. Felkin, G. E. Morris, J. Organomet.
Chem. 1977, 141, 205 – 215.
[24] D. L. Reger, C. A. Little, J. J. S. Lamba, K. J. Brown,
J. R. Krumper, R. G. Bergman, M. Irwin, J. P. Fackler,
Inorg. Synth. 2004, 34, 5 – 8.
[8] J. Sprinz, G. Helmchen, Tetrahedron Lett. 1993, 34,
1769 – 1772.
[9] R. N. Constantine, N. Kim, R. C. Bunt, Org. Lett. 2003,
5, 2279 – 2282.
[10] J. V. Allen, G. J. Dawson, C. G. Frost, J. M. J. Williams,
S. J. Coote, Tetrahedron 1994, 50, 799 – 808.
[11] K. Tani, D. C. Behenna, R. M. McFadden, B. M. Stoltz,
Org. Lett. 2007, 9, 2529 – 2531.
[12] A. Frolander, S. Lutsenko, T. Privalov, C. Moberg, J.
Org. Chem. 2005, 70, 9882 – 9891.
[25] C. A. Busacca, J. C. Lorenz, N. Grinberg, N. Haddad,
M. Hrapchak, B. Latli, H. Lee, P. Sabila, A. Saha,
M. Sarvestani, S. Shen, R. Varsolona, X. Wei, C. H.
Senanayake, Org. Lett. 2005, 7, 4277 – 4280.
[26] M. P. Cava, R. L. Litle, D. R. Napier, J. Am. Chem. Soc.
1958, 80, 2257 – 2263.
[13] G. Koch, G. C. Lloyd-Jones, O. Loiseleur, A. Pfaltz,
R. Pretot, S. Schaffner, P. Schnider, P. von Matt, Recl.
Trav. Chim. Pays-Bas 1995, 114, 206 – 210.
[14] M. Zehnder, S. Schaffner, M. Neuburger, D. A. Plat-
tner, Inorg. Chim. Acta 2002, 337, 287 – 298.
[15] D. G. Blackmond, A. Lightfoot, A. Pfaltz, T. Rosner,
P. Schnider, N. Zimmermann, Chirality 2000, 12, 442 –
449.
[27] A. Sudo, K. Saigo, Tetrahedron: Asymmetry 1996, 7,
2939 – 2956.
[28] A. Sudo, K. Saigo, J. Org. Chem. 1997, 62, 5508 –
5513.
[29] A. Frolander, S. Lutsenko, T. Privalov, C. Moberg,
J. Org. Chem. 2005, 70, 9882 – 9891.
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