Improved one-pot synthesis of C3-symmetric clickphos and related ligands: Structures of unique triazole-zinc complexes

Article abstract of DOI:10.1002/ejoc.201001505

A number of ClickPhos-type ligands have been prepared by using an improved one-pot procedure. Several [tris(triazolyl)phosphane]zinc complexes have been synthesized and characterized by X-ray structure analyses. An improved one-pot synthesis leads to vari

Full text of DOI:10.1002/ejoc.201001505

SHORT COMMUNICATION
DOI: 10.1002/ejoc.201001505
Improved One-Pot Synthesis of C3-Symmetric ClickPhos and Related Ligands:
Structures of Unique Triazole–Zinc Complexes
Daniel M. Zink,[a,b] Thomas Baumann,*[b] Martin Nieger,[c] and Stefan Bräse*[a]
Keywords: ClickPhos / Triazole / Click chemistry / Zinc / Helical structures
A number of ClickPhos-type ligands have been prepared by
using an improved one-pot procedure. Several [tris(triazolyl)-
phosphane]zinc complexes have been synthesized and char-
acterized by X-ray structure analyses.
the ClickPhos ligand, but also extends the reaction se-
quence to a total of 4 steps, while in our case the one-pot
synthesis allows for a simple preparation and modulation
of the corresponding ClickPhos ligands. In addition, by use
of our protocol, we can also introduce an additional sub-
stituent in position 5 of the triazole ring, which is not ac-
cessible by means of classic click chemistry.
Crystal structures of metal complexes with mono-, bis-
or tris(triazolyl)phosphanes are very rare in the literature.
Except for the work by Lammertsma et al. in which phos-
phor and nitrogen coordination was combined to give ac-
cess to a dimetallic Mo/W complex, there are, to the best
of our knowledge, no other complexes with tris(triazolyl)-
phosphanes as ligands. Although, some very few complexes
with triazolylphosphanyl- or triazolylphosphanothioyl as
bidentate ligands coordinating through the nitrogen atom
and the oxygen or rather the sulfur atom instead of the
phosphorus atom, e.g. with Co, Rh, Ni,[7] and Pd,[8] are
known, metal complexes with mono- or bis(triazolyl)phos-
phanes with a bidentate phosphorus/nitrogen complexation
behavior have not yet been reported.
Introduction
The synthesis of novel modular ligand systems has
gained considerable attention due to their pivotal role in
metal catalysis. Consequently, the need for efficient routes
to such compounds is of increasing interest. In the field of
cross-coupling reactions mono- and bidentate ligands based
on the triazole scaffold 4[1] have been successfully employed
as potent catalysts[2] in several processes, for example Su-
zuki reactions or the amination of aryl chlorides.[3] In ad-
dition, chiral variants have been used for hydrogenation re-
actions, allylic substitution reactions or reductive aldol re-
actions.[4]
Most of such ligands can be synthesized according to
Sharpless by a two-step procedure.[5] Even though Zhang et
al. reported a one-pot synthesis to furnish various members
of the ClickPhos family, they preferred the two-step pro-
cedure by Sharpless, because of an easier purification of the
products.[2] Nevertheless, we used and improved the above
described one-pot synthesis by Zhang et al. to provide an
easy access not only to members of the ClickPhos family,
but also to bis- and tris(triazolyl)phosphanes. These kinds
of bi- and tridentate ligands have only been described in the
literature by Lammertsma et al.,[6] but for their synthesis,
which makes use of “classic” click conditions, they state
that the phosphorus center has to be protected in order to
prevent a Staudinger reduction to occur. This protection
not only requires a final deprotection procedure to furnish
Results and Discussion
As described in the original paper,[5] by starting from an
azide, the reaction with an alkynylmagnesium salt leads to a
metallated triazole intermediate 3-MgBr. Aqueous workup,
metallation with LDA and treatment with chlorophos-
phanes gives rise to the ClickPhos family.[2] Herein we re-
port a simplified and optimized procedure,[9] which allows
for the synthesis of a number of new members of this
family. For the first step, we used the procedure as described
by Sharpless et al. employing the Grignard reagents to form
the corresponding magnesium salt 1 starting with an alkyne
at low temperature. Subsequent addition of aryl or alkyl
azides 2 (1.10 equiv.)[10] at slightly elevated temperature
forms the triazolylmagnesium salt 3-MgBr (Scheme 1).
[a] Institute for Organic Chemistry, Karlsruhe Institute of
Technology (KIT),
Fritz-Haber-Weg 6, 76131 Karlsruhe, Germany
Fax: +49-721-608-8581
E-mail: braese@kit.edu
[b] Cynora GmbH,
Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-
Leopoldshafen, Germany
[c] Laboratory of Inorganic Chemistry, Department of Chemistry,
University of Helsinki,
P. O. Box 55 (A.I. Virtasen aukio 1), 00014 University of
Helsinki, Finland
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001505.
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C3-Symmetric ClickPhos and Related Ligands
Scheme 1. Conventional and improved synthesis of ClickPhos
members.[9]
Direct treatment of these salts with various diarylchlo-
rophosphanes (1.20 equiv.) furnished the triazoles 4a–d in
moderate to good yields. This method can be carried out
on a gram scale, while the yields are comparable with the
two-step procedure described by Zhang et al.[2] The only
by-products are the protonated triazoles 3-H (7–27%),
which can be removed easily by flash chromatography.
This new method was extended to dichloro(phenyl)phos-
phanes, which results in the formation of novel bis(triazol-
yl)phosphanes 4e,f. In addition, the use of phosphorus tri-
chloride[11] allowed for the synthesis of new tris(triazolyl)-
phosphanes 4g,h in good yields. The latter ligands are re-
lated to the well-known scorpionate ligands (Scheme 2).[12]
In order to proof their complex formation ability, we syn-
thesized several zinc complexes by reaction of the triazol
ligands with the corresponding zinc halide in dichlorometh-
ane, with the complexation being completed after a few
hours. The purification of the complexes was achieved by
precipitation of the filtered reaction mixture in cyclohexane.
The synthesized complexes are summarized in Table 1, and
the three-dimensional structure of the tris(triazolyl)phos-
phane ligand 4g and two corresponding zinc complexes of
4h (6) and 4g (7) were determined by X-ray structure analy-
sis.
Scheme 2. Synthesis of new ClickPhos members. For details, see
the Exp. Sect.
Table 1. Synthesized zinc complexes.
Compound Ligand Metal salt Stoichiometry[a] Yield [%]
5
6
7
4g
4h
4g
ZnBr2
ZnBr2
ZnI2
[L2Zn][Zn2Br6]
[L2Zn][Zn2Br6]
LZnI2
11
30
85
As seen in Figure 1, the tris(1,5-diphenyl-1H-1,2,3-tri-
azol-4-yl)phosphane (4g) has a helical structure and C3 sym-
metry. The phosphorus atom is coordinated by three carbon
atoms, which form, together with the free electron pair of
the central phosphorus atom the corners of a tetrahedron.
This geometry can therefore undergo several different coor-
dination modes such as a tripodal complexation involving
[a] Based on mass spectrometry and X-ray crystallography.
three nitrogen atoms, one from each triazol ring, thereby two tris(triazolyl)phosphane ligands together with a zinc
behaving like the related tris(pyrazolyl)phosphane oxide ion, and the anionic part being composed of two zinc and
that complexes to CuI,[13a] ZnCl2,[13a] TlI,[13b] and Mo- four bromide ions. In the twofold positively charged cat-
[13c]
(CO)3
(Figure 1). Another possibility to coordinate to ionic part, the zinc ion is octahedrally coordinated by six
a metal atom is provided by the lone electron pair of the nitrogen atoms of two tris(1,5-diphenyl-1H-1,2,3-triazol-4-
phosphorus atom. In addition, both coordination modes yl)phosphane ligands. The coordination to the metal core
can occur within the same complex. All of these different occurs solely by the nitrogen atom in 3-position of the tri-
coordination modes have been shown by Lammertsma et azole ring, which results in very similar zinc–nitrogen bond
al.[6] in several carbonyl[tris(triazolyl)phosphane]rhodium, lengths in the range of 2.103–2.196 Å. This cationic part of
-tungsten, or -molybdenum complexes.
the complex exhibits an inversion centre on the zinc ion and
The crystal structure analysis of compound 6 revealed a twofold screw axis. The counter anion of the complex,
the a charged complex, with the cationic part consisting of which is formed by two zinc and six bromide ions, has the
Eur. J. Org. Chem. 2011, 1432–1437
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D. M. Zink, T. Baumann, M. Nieger, S. Bräse
SHORT COMMUNICATION
Figure 3. X-ray structure of complex 7.
Figure 1. X-ray structure of tris(1,5-diphenyl-1H-1,2,3-triazol-4-
yl)phosphane (4g).
Since both complexes 6 and 7 feature an almost identical
ligand system, a rational explanation for the different geo-
metrical structures might account for the different zinc ha-
lides. On the one hand, the structure of tetrahedrally coor-
dinated zinc complexes is well known in the literature, and
therefore, it appears that complex 7 represents the expected
structural motif for this kind of complexes. On the other
hand, zinc complexes with an octahedrally coordinated zinc
ion are also widely established in the literature. In the case
of complex 6, the formation of the unusual counterion
[Zn2Br6]2– to compensate for the positive charge could facil-
itate the octrahedral coordination of the central zinc ion by
two triazole ligands. Even though an equivalent structural
motif for [Zn2I6]2– exists in the literature (although in con-
trast to [Zn2Cl6]2–, a structurally well-characterized spe-
cies), only a few examples of [Zn2Br6]2– and [Zn2I6]2– are
known.[15] Therefore, there is no obvious reason, why in the
case of complex 6 dismutation into a fully nitrogen-coordi-
nated cation and a fully halide-coordinated anion has oc-
curred. The formation of the tetrahedral complex 7 might
result from the lower donor strength of the triazole nitrogen
atom, which cannot compete against the two iodide ligands
for coordination to the zinc atom. Eventually, the size of the
halide atoms is also important for the formation of either
complex 6 or complex 7.
structure of two edge-sharing tetrahedrons (Figure 2). It
possesses therefore three mirror planes, an inversion centre
and three twofold screw axes.[14]
Figure 2. X-ray structure of complex 6.
Another explanation might consider the formation of a
second coordination sphere out of two complexes as some
kind of loose dimer with distorted trigonal-bipyramidal ge-
Although several characterization techniques such as ometry, in which the two nitrogen atoms and I2 adopt the
mass spectrometry suggest an identical coordination mode equatorial positions and I1 and I2(#1) the axial positions.
and geometry to that of complex 6, we have not been able In each moiety, one of the iodine atoms acts as a bridging
to obtain any suitable crystals of complex 5 for X-ray analy- ligand to the zinc ion of the other moiety, whereas the other
sis yet.
iodide ion is a terminal ligand (Figure 4). Such pentacoor-
In contrast, complex 7 adopts an “open” structure by dinate zinc complexes represent a well-known structural
coordination of only two nitrogen atoms of one tris(1,5- motif,[16] but so far only a few examples with a pentacoordi-
diphenyl-1H-1,2,3-triazol-4-yl)phosphane (4g), and two nate zinc ion including two iodide ions and no example for
iodide ions in a distorted tetrahedral coordination. The a pentacoordinate complex including three iodide ions have
third triazole ring is rotated away from any complexation been reported. The Zn(1)–I(1) distance with 2.54 Å is in the
ability and therefore prevents a third nitrogen coordination range of comparable complexes with covalent Zn–I
of the zinc ion (Figure 3).
bonds;[16e] however, the Zn(1)–I(2)#1 distance with 4.28 Å
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Eur. J. Org. Chem. 2011, 1432–1437

C3-Symmetric ClickPhos and Related Ligands
lies in the range of literature-known ionic interactions be- Zhang et al. for ClickPhos ligands. By modifying this syn-
tween Zn and I.[17] According to these values, a second co- thetic route, we developed a possibility to synthesize bis-
ordination sphere in the crystal structure of complex 7, and tris(triazolyl)phosphane ligands. Several novel [tris(tri-
which is formed through ionic interactions between two azolyl)phosphane]zinc complexes have been prepared for
zinc and two iodide ions, might be taken into account the first time, and X-ray structure analyses revealed two
(Table 2).
different kinds of structures. We will explore these new li-
gands and complexes for their properties in catalysis, for
example copper- and/or palladium-catalyzed cross coupling
methodologies, such as Suzuki, Negishi or Sonogashira re-
actions.
Experimental Section
General: All reactions were performed in oven-dried glassware un-
der argon. Solvents and chemicals used were purchased from com-
mercial suppliers. Solvents were dried by standard conditions. All
materials were used without further purification. Thin-layer
chromatography (TLC) was carried out on silica gel plates (Kiesel-
gel 60, F254, Merck) with detection by UV spectroscopy. Purifica-
tion was performed by preparative chromatography on normal-
1
phase silica gel (Silica gel 60, 230–400 mesh, Merck). H, 13C and
31P NMR spectra were recorded with a Bruker AM 400 or a Bruker
DRX 250 spectrometer. Chemical shifts are reported as δ values
(ppm). The signal abbreviations include: Ar-H = aromatic proton.
The signals of the 13C NMR spectra were allocated by the DEPT
(Distortionless Enhancement by Polarisation Transfer) technology.
The signal abbreviations include: C-Ar = aromatic carbon atom, +
= primary or tertiary carbon atom, – = secondary carbon atom,
Cquat = quaternary carbon atom.
Figure 4. Second coordination sphere of complex 7.
Table 2. Selected bond lengths [Å] and angles [°] for 7.[a]
I(1)-Zn(1)
I(2)-Zn(1)
I(2)-Zn(1)#1
I(2)–I(2)#1
Zn(1)–N(1)
Zn(1)–N(18)
Zn(1)–I(2)#1
2.5434(6)
2.5436(6)
4.2836(7)
4.3055(6)
2.075(3)
2.086(3)
4.2836(7)
4,4Ј-(Phenylphosphanediyl)bis(1,5-diphenyl-1H-1,2,3-triazole) (4e):
Ethylmagnesium chloride (2.0 m in tetrahydrofuran, 5.00 mL,
10.0 mmol, 2.00 equiv.) was diluted with dry tetrahydrofuran
(10 mL). Phenylethyne (1.02 g, 10.0 mmol, 2.00 equiv.) was added
slowly through cannula. After 15 min at 50 °C, the mixture was
cooled to room temperature, and phenyl azide (1.31 g, 11.0 mmol,
2.20 equiv.) was added through cannula. The mixture was stirred
at room temperature for 40 min and at 50 °C for 1 h, after which
it was cooled to room temperature. Dichloro(phenyl)phosphane
(0.89 g, 5.00 mmol, 1.00 equiv.) in dry tetrahydrofuran (10 mL) was
added, and the mixture was stirred at room temperature for 4.5 h.
The reaction was quenched with water (50 mL), the phases were
separated, and the aqueous phase was extracted with ethyl acetate
(3ϫ50 mL). The combined organic phases were washed with brine
(60 mL) and dried with magnesium sulfate. Purification by flash
chromatography (4.5 cm, cyclohexane/ethyl acetate, 5:1 Ǟ 1:1)
yielded 1.62 g (3.00 mmol, 60%) of an orange solid. M.p. 185–
195 °C. Rf = 0.64 (cyclohexane/ethyl acetate, 1:1). 1H NMR
(400 MHz, CDCl3): δ = 6.95–6.97 (m, 2 H, Ar-H), 7.10–7.17 (m, 9
H, Ar-H), 7.20–7.27 (m, 10 H, Ar-H), 7.77–7.82 (m, 2 H, Ar-H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 124.9 (+, C-Ar), 126.8
(Cquat), 128.2 (+, C-Ar), 128.3 (+, C-Ar), 128.8 (+, C-Ar), 129.0
(+, C-Ar), 129.0 (+, C-Ar), 129.4 (+, C-Ar), 130.0 (+, C-Ar), 130.1
(+, C-Ar), 133.0 (Cquat), 134.7 (+, C-Ar), 134.9 (+, C-Ar), 136.4
Zn(1)–I(2)–Zn(1)#1
Zn(1)–I(2)–I(2)#1
Zn(1)#1-I(2)–I(2)#1
N(1)–Zn(1)–N(18)
N(1)–Zn(1)–I(1)
N(18)–Zn(1)–I(1)
N(1)–Zn(1)–I(2)
N(18)–Zn(1)–I(2)
I(1)–Zn(1)–I(2)
N(1)–Zn(1)–I(2)#1
N(18)–Zn(1)–I(2)#1
I(1)–Zn(1)–I(2)#1
I(2)–Zn(1)–I(2)#1
106.754(15)
72.302(15)
34.451(9)
91.18(11)
113.39(8)
112.41(8)
109.65(8)
112.05(8)
115.649(18)
61.33(8)
62.03(8)
171.105(15)
73.246(15)
[a] Symmetry transformations used to generate equivalent atoms:
#1: –x + 1, –y + 1, –z.
However, at this point, and based on the few examples,
no clear explanations can be given so far. Further structural
and theoretical investigations will help to better understand
the parameters that effect the different coordination geome-
tries.
1
1
(Cquat), 140.5 (d, JCP = 6.5 Hz, Cquat), 142.0 (d, JCP = 33.1 Hz,
Cquat
,
C-4, C-4Ј) ppm. 31P NMR (101 MHz, CDCl3): δ =
–57.5 ppm. IR (drift): ν = 3065 (m), 2928 (m), 2853 (w), 2337 (w),
˜
Conclusions
1967 (w), 1885 (w), 1815 (w), 1739 (m), 1595 (m), 1497 (m), 1448
(m), 1411 (m), 1271 (m), 1064 (m), 998 (m), 918 (m), 771 (m), 697
In order to simply access this kind of mono(triazolyl)-
phosphane ligands, we improved the one-pot syntheses of (m), 597 (m), 514 (m) cm–1. MS (70 eV, EI): m/z (%) = 548 (6)
Eur. J. Org. Chem. 2011, 1432–1437
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1435

D. M. Zink, T. Baumann, M. Nieger, S. Bräse
SHORT COMMUNICATION
[M+], 491 (6) [M+ – 2 N2], 333 (13), 300 (15), 221 (30), 193 (100),
165 (48). HR-EIMS: calcd. for C34H25N6P 548.1878; found
548.1877.
Acknowledgments
Financial support from the Deutsche Forschungs-Gemeinschaft
(DFG) funded transregional collaborative research center SFB/
TRR 88 “3MET” is acknowledged.
[{Tris(5-butyl-1-phenyl-1H-1,2,3-triazol-4-yl)phosphane}2zinc]-
[Zn2Br6] (6): Zinc bromide (104 mg, 0.47 mmol, 1.00 equiv.)
and tris(5-butyl-1-phenyl-1H-1,2,3-triazol-4-yl)phosphane (4h)
(300 mg, 0.47 mmol, 1.00 equiv.) were dissolved under nitrogen in
dry dichloromethane (8 mL). The solution was stirred at room tem-
perature for 12 h. The complex was precipitated in cyclohexane,
filtered and dried in vacuo and obtained as a white solid (270 mg,
0.14 mmol, 30%). 1H NMR (400 MHz, [D6]DMSO): δ = 0.63 (t, J
= 7.3 Hz, 9 H, CH3), 1.02–1.14 (m, 24 H, CH3CH2CH2), 2.87–2.96
[1] For example, palladium catalysis: a) E. M. Schuster, M. Boto-
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2002, 330, 38–43.
(m, 12 H, CH3CH2CH2CH2), 7.51–7.71 (m, 30 H, Ar-H) ppm. 13
C
NMR (100 MHz, [D6]DMSO): δ = 13.2 (+, CH3), 21.5 (–,
CH3CH2CH2CH2), 22.3 (–, CH3CH2), 30.0 (–, CH3CH2CH2),
125.1 (+, C-Ar), 125.4 (+, C-Ar), 129.6 (+, C-Ar), 129.6 (+, C-Ar),
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1
(d, JCP = 27.8 Hz, Cquat) ppm. IR (drift): ν = 2957 (vw), 2929
˜
[4] a) H. Oki, I. Oura, T. Nakamura, K. Ogata, S. Fukuzawa, Tet-
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(vw), 2870 (vw), 1595 (w), 1497 (w), 1458 (w), 1012 (w), 768 (w),
692 (w), 577 (w), 515 (w) cm–1. MS (FAB): m/z (%) = 1160 (Ͻ1)
[LZn2Br5], 1189 (Ͻ1) [LZn2Br4], 848 (11) [LZn2Br], 776 (67)
[LZnBr], 160 (100); L = 4h. C72H84Br6N18P2Zn3 (1939.09): calcd.
C 44.60, H 4.37, N 13.00; found C 44.40, H 4.47, N 12.61.
Crystal Structure Determination of 4g, 6 and 7: The single-crystal
X-ray diffraction study was carried out with a Bruker-Nonius
Kappa-CCD diffractometer at 123(2) K by using Mo-Kα radiation
(λ = 0.71073 Å). Direct methods (SHELXS-97[18]) were used for
structure solution, and refinement was carried out by using
SHELXL-97[18] (full-matrix least squares on F2). Non-hydrogen
atoms were refined anisotropically, hydrogen atoms were localized
by difference electron density determination and refined by using
a riding model. A semiempirical absorption correction was applied
for 6 and 7. In 7 the solvent CH2Cl2 is disordered about a centre
of symmetry. 4g: Colourless crystals, C42H30N9P, M = 691.72, crys-
tal size 0.32ϫ0.16ϫ0.08 mm, monoclinic, space group P21/c (No.
14), a = 16.841(1) Å, b = 9.837(1) Å, c = 21.057(1) Å, β = 93.80(1)°,
V = 3480.7(4) Å3, Z = 4 ρ(calcd.) = 1.320 Mgm–3, F(000) = 1440,
μ = 0.125 mm–1, 66160 reflections (2θmax = 55°), 7971 unique (Rint
= 0.046), 469 parameters, R1 [IϾ2σ(I)] = 0.045, wR2 (all data) =
0.114, S = 1.04, largest diff. peak/hole 0.356/–0.302 eÅ–3. 6: Pale
yellow crystals, C72H84N18P2Zn2+ – Br6Zn22–, M = 1939.08, crystal
[5] A. Krasinski, V. V. Fokin, K. B. Sharpless, Org. Lett. 2004, 6,
1237–1240.
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Chim. Acta 2002, 330, 38–43.
[9] This has been already suggested by Zhang et al.:[2] “It is worthy
of note that the ligand synthesis could be shortened into a one-
pot operation with comparable crude yield of the desired product
by directly quenching the intermediate 5 with a chlorophosphane.
The isolation of triazole 6 prior to installation of the phosphanyl
substituents is solely because of the ease of purification of the
final phosphane ligands.” We did not observe any problems dur-
ing purification.
¯
size 0.24ϫ0.09ϫ0.03 mm, triclinic, space group P1 (No. 2), a =
12.1596(9) Å, b = 12.5221(9) Å, c = 14.8539(18) Å, α = 94.050(9)°,
β = 101.684(7)°, γ = 117.543(5)°, V = 1928.4(3) Å3, Z = 1, ρ(calcd.)
= 1.670 Mgm–3, F(000) = 972, μ = 4.130 mm–1, 22355 reflections
(2θmax = 50°), 6761 unique (Rint = 0.082), 457 parameters, R1
[IϾ2σ(I)] = 0.063, wR2 (all data) = 0.146, S = 1.06, largest diff.
peak/hole 0.950/–0.593 eÅ–3. 7: Yellow crystals, C42H30I2N9PZn –
0.5CH2Cl2, M = 1053.35, crystal size 0.24ϫ0.12ϫ0.08 mm, tri-
[10] SAFETY: Whereas ionic azides such as sodium azide are rela-
tively stable, carbon-bound or heavy-metal azides are subject
to thermal – sometimes explosive – decomposition. Some or-
ganic and other covalent azides are classified as toxic and
highly explosive, and appropriate safety measures must be
taken at all times: S. Bräse, C. Gil, K. Knepper, V. Zimmer-
mann, Angew. Chem. 2005, 117, 5320; Angew. Chem. Int. Ed.
2005, 44, 5188.
[11] Comments: Phosphorus trichloride is controlled under the
Chemical Weapons Convention. PCl3 is toxic, with a concen-
tration of 600 ppm being lethal in just a few minutes. It is clas-
sified as very toxic and corrosive under EU Directive 67/548/
EEC, and the risk phrases R14, R26/28, R35 and R48/20 are
obligatory.
¯
clinic, space group P1 (No. 2), a = 12.073(1) Å, b = 12.602(1) Å, c
= 14.906(2) Å, α = 110.38(1)°, β = 94.94(1)°, γ = 95.19(1)°, V =
2100.3(4) Å3, Z = 2, ρ(calcd.) = 1.666 Mgm–3, F(000) = 1034, μ =
2.199 mm–1, 27829 reflections (2θmax = 55°), 9602 unique (Rint
=
0.035), 514 parameters, 3 restraints, R1 [IϾ2σ(I)] = 0.037, wR2 (all
data) = 0.079, S = 1.03, largest diff. peak/hole 0.987/–1.266 eÅ–3.
CCDC-799089 (4g), -799090 (6) and -799091 (7) contain the sup-
plementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
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Supporting Information (see footnote on the first page of this arti-
cle): Analytical data for all prepared compounds (4–7).
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 1432–1437

C3-Symmetric ClickPhos and Related Ligands
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Received: November 9, 2010
Published Online: February 3, 2011
Eur. J. Org. Chem. 2011, 1432–1437
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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