Octakis(3-azidopropyl)octasilsesquioxane: A versatile nanobuilding block for the efficient preparation of highly functionalized cube-octameric polyhedral oligosilsesquioxane frameworks through click assembly

Article abstract of DOI:10.1002/chem.200902422

A one-step synthesis of octa-kis(3-azidopropyl)octasilsesquioxane from commercially available octakis(3-aminopropyl)octasilsesquioxane has been developed through a highly effi-cient diazo-transfer reaction under very mild conditions. Nonaflyl azide is sho

Full text of DOI:10.1002/chem.200902422

FULL PAPER
DOI: 10.1002/chem.200902422
Octakis(3-azidopropyl)octasilsesquioxane: A Versatile Nanobuilding Block
for the Efficient Preparation of Highly Functionalized Cube-Octameric
Polyhedral Oligosilsesquioxane Frameworks Through Click Assembly
Beatriz Trastoy,[a] M. Eugenia Pꢀrez-Ojeda,[b] Roberto Sastre,[b] and Jose Luis Chiara*[a]
This work is dedicated to the memory of Professor Antonio Gꢀmez-Sꢁnchez
Abstract: A one-step synthesis of octa-
kis(3-azidopropyl)octasilsesquioxane
from commercially available octakis(3-
used diazo-transfer reagent triflyl
azide. Octakis(3-azidopropyl)octasilses-
quioxane is an excellent nanobuilding
block that can be readily octafunction-
alized with a range of terminal alkynes
by
copper(I)-catalyzed
1,3-dipolar
azide–alkyne cycloaddition to provide
new functional nanocages, maintaining
a perfect 3D cubic symmetry. The mild-
ness, simplicity, and efficiency of this
approach have been demonstrated in
the preparation of a glyco-polyhedral
oligosilsesquioxane (POSS) conjugate
aminopropyl)octasilsesquioxane
has
been developed through a highly effi-
cient diazo-transfer reaction under very
mild conditions. Nonaflyl azide is
shown to be a safer, cheaper, and more
efficient reagent for this transformation
than the better known and generally
Keywords: azides · carbohydrates ·
click chemistry · dyes/pigments ·
silsesquioxanes
and
a
BODIPY–POSS
cluster
(BODIPY=boron dipyrromethene).
Introduction
gies for the synthetic manipulation of their pendant organic
groups (see below), and the recent commercial availability
of a wide range of simple monomers on a multigram scale[6]
have contributed to the fast development of POSS chemistry
in the last decades. Applications in areas as diverse as poly-
mers, composite materials, dendrimers, optical materials,
liquid crystals, drug carriers, metal catalysts, and cosmetics
have been described over the past several years, especially
in the patent literature.[7] The most promising POSS mono-
mers are the highly symmetrical and topologically ideal
cube-octameric frameworks (T8), of general formula type
(RSiO1.5)8. Among these, octahydridooctasilsesquioxane
(1),[8–10] the simplest T8 compound, together with octaviny-
loctasilsesquioxane (2),[5,11,12] octaphenyloctasilsesquioxane
(3),[3,5,13] octakis(3-chloropropyl)octasilsesquioxane (4),[14–18]
and octakis(3-aminopropyl)octasilsesquioxane (5)[19–22] have
been the most useful precursors to a variety of T8 products.
Key to all potential uses of these POSS basic monomers is
the ease with which their pendant organic functionality can
be altered in a controlled and highly efficient way to pro-
duce new molecules suitable for further functionalization.
Since these T8 molecules contain eight points for functionali-
zation and partial transformation produces complex mix-
tures of products that are generally difficult to separate, it is
critical that the reaction chosen for this task proceeds in a
very efficient way. A relatively wide range of derivatization
Fully condensed polyhedral oligosilsesquioxanes (POSS) are
unique nanometer-sized hybrid inorganic–organic materials
of chemical composition (RSiO1.5)n, which can be readily
synthesized by hydrolytic condensation of trifunctional orga-
nosilicon monomers RSiX3 (R=organic group; X=halogen
or alkoxide group).[1] Due to their rigid inorganic core,
POSS are endowed with considerable chemical and thermal
stability. Although this family of compounds has been
known for more than 60 years,[2] until the past decade, the
majority of commonly available POSS derivatives lacked
sufficient functionality for most chemical applications. The
discovery of new spontaneous self-assembly reactions[3–5]
that provide ready access to a variety of novel POSS frame-
works, the development of general and efficient methodolo-
[a] B. Trastoy, Dr. J. L. Chiara
Instituto de Quꢀmica Orgꢁnica General, CSIC
Juan de La Cierva, 3, 28006 Madrid (Spain)
Fax : (+34)91-564-4853
E-mail: jl.chiara@iqog.csic.es
[b] M. E. Pꢂrez-Ojeda, Prof. Dr. R. Sastre
Instituto de Ciencia y Tecnologꢀa de Polꢀmeros
CSIC, Juan de La Cierva, 3, 28006 Madrid (Spain)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.200902422.
Chem. Eur. J. 2010, 16, 3833 – 3841
ꢃ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
3833

reactions are suited for this purpose, although care must be
taken to avoid strongly acidic, basic, or oxidizing environ-
ments that can compromise the stability of the POSS cage.
Transition metal-catalyzed reactions such as hydrosilyla-
tion,[14,–19–29] olefin cross-metathesis,[28,30–32] and Heck,[28,33–37]
Suzuki,[28,36] or Sonogashira[28,36] couplings; acylation[21,38–41]
and Michael addition[21,42] reactions of amines; electrophilic
aromatic substitution reactions;[36,43–47] nucleophilic substitu-
tion of halogen;[14,17,48–50] and radical addition of thiols[51,52]
or R2PH[53–55] to olefins, have been used for this purpose
with great success. Surprisingly, the copper(I)-catalyzed 1,3-
dipolar Huisgen cycloaddition of azides to alkynes
(CuAAC),[56–58] a paradigmatic example of a “click reac-
tion”,[59] which is a robust and reliable method for the effi-
cient functionalization of a wide variety of molecules under
mild conditions, has been scarcely used in POSS chemistry
because of the lack of appropriately functionalized POSS
derivatives.[60]
agents for the synthesis of 6: trifluoromethanesulfonyl
(triflyl) azide, which has often been used for the preparation
of organic azides from the corresponding primary amines,
mostly in carbohydrate chemistry;[69–71] and nonafluorobu-
AHCTUNGTRENNUNG
tanesulfonyl (nonaflyl) azide,[72,73] which at the onset of our
work had never been used before for the synthesis of organ-
ic azides.[74] Triflyl azide is potentially explosive, it has a rel-
atively poor shelf life and it must be prepared just before
use from triflic anhydride and sodium azide as a solution in
dichloromethane[69,75] or toluene.[76] In contrast, nonaflyl
azide is stable at room temperature, can be safely distilled
and kept as a neat reagent at 48C for later use without de-
composition, and is easily obtained from the much cheaper
and readily available nonaflyl fluoride.[72,73] In an initial
screening of reaction conditions (Table 1), we identified two
Table 1. Synthesis of 6 from 5·8HCl by diazo-transfer reaction.[a]
Entry
RF
Solvent (v/v ratio)
Yield[b] [%]
1[c]
2
3
4
5
CF3
CF3
CF3
CF3
CF3
toluene/MeOH/H2O (7.8:11:0.2)
toluene/MeOH/H2O (7.8:11:0.2)
toluene/EtOH/H2O (7.8:11:0.2)
toluene/iPrOH/H2O (7.8:11:0.2)
toluene/tBuOH/H2O (7.8:11:0.2)
Et2O/EtOH/H2O (1:3:1)
17–20
28–30
50–54
55
42
60–73
6
CF3A
G
[a] Reaction conditions: 5·8HCl (1 mol equiv), RFSO2N3 (RF =CF3, ca.
36 mol equiv; RF =(CF2)3CF3, 24 mol equiv), CuSO4·5H2O
(0.5 mol equiv), NaHCO3 (32 mol equiv), RT, 16 h. [b] Yield of pure
product after chromatography. [c] Compound 5 was added to the reaction
as a solution in MeOH (prepared by stirring a suspension of 5·8HCl in
this solvent with an excess of Amberlite IRA-400/OH at 08C).
Herein, we report the synthesis of the new octaazide-
POSS 6 with a perfect 3D cubic symmetry, and an initial
screening of reaction conditions for its octafunctionalization
with a variety of alkynes through CuAAC reaction. To ex-
amine the scope and utility of this methodology for the
preparation of new functional materials, we have undertak-
en the assembly of a multivalent POSS glycoconjugate[61]
and a POSS–fluorophore cluster.[62] Synthetic multivalent
glycoconjugates are interesting constructs for the study of
factors that were critical to obtain an optimal yield of 6. The
first is the procedure employed for the required neutraliza-
tion of 5·8HCl to the free amine, which is known to be diffi-
cult to accomplish without compromising the Si/O frame-
work.[21] In situ neutralization by incorporation of an excess
of an aqueous solution of NaHCO3 in the diazo-transfer re-
action (Table 1, entries 2–6) afforded better yields than the
previously described[21] pretreatment of 5·8HCl with Amber-
lite IRA-400/OH resin in methanol (Table 1, entry 1). The
second factor affecting the yield is the reaction solvent. Ho-
mogenous solvent mixtures containing water, a simple alco-
hol, and an apolar organic solvent were needed to solubilize
all reaction components. Toluene was used as the apolar or-
ganic solvent in the case of triflyl azide (Table 1, entries 1–
5),[76] whereas diethyl ether was required to dissolve the
nonaflyl reagent (Table 1, entry 6). Mixtures containing eth-
anol or isopropanol as the alcohol component afforded the
best yields (Table 1, entries 3, 4, and 6). In gram-scale prepa-
rations of 6, the order of addition of reagents was also of im-
portance. When NaHCO3 was added to an aqueous solution
of 5·8HCl and CuSO4·H2O, a blue precipitate appeared,
which was probably formed from a mixture of CuII com-
plexes of 5. Under these conditions, yields usually halved
due to the persistent heterogeneous nature of the reaction.
Precipitation can be largely avoided by adding NaHCO3 last
carbohydrate–protein recognition processes and have
a
number of other potential practical applications, including
the prevention of early adhesion of pathogens to host epi-
thelial cells, the neutralization of viruses and toxins, the
preparation of vaccines, and carbohydrate-guided targeted
drug delivery.[64–66] On the other hand, multimeric fluores-
cent molecules have been used as chemosensors for H+ or
metal ions, biological probes, optical brighteners, light-har-
vesting devices, or as potential compounds for organic light-
emitting diodes.[67,68]
Results and Discussion
We prepared compound 6 from the corresponding octaami-
no-POSS 5 by using an efficient diazo-transfer reaction.
Compound 5 is commercially available as its octahydro-
chloride salt[6] and can be easily obtained in multigram
quantities from an inexpensive organosilicon precur-
sor.[19,20,38] We examined two different diazo-transfer re-
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Chem. Eur. J. 2010, 16, 3833 – 3841

Polyhedral Oligosilsesquioxane Frameworks
FULL PAPER
and in small portions under very efficient stirring. Eventual-
ly, nonaflyl azide proved to be the reagent of choice for this
transformation, both for its higher efficiency and for its
much lower cost. Under the optimized conditions (Table 1,
entry 6), compound 6 was obtained in gram amounts as a
viscous liquid in 60–73% yield after chromatographic purifi-
cation, which accounts for an excellent yield per amino
group (>94%) in the diazo-transfer reaction. The structure
of 6 was unambiguously confirmed from its high-resolution
mass spectrometry and FTIR and NMR spectroscopy data
(Figure 1). Thus, a strong IR band at 2099 cmÀ1 (characteris-
and 13C NMR spectra, and a narrow singlet resonance in the
29Si NMR spectrum revealed the perfect 3D cubic symmetry
of this compound.
Very recently, Ge et al.[60c] have described a different syn-
thesis of 6 through nucleophilic substitution reaction of octa-
kis(3-chloropropyl)octasilsesquioxane (4) with NaN3. How-
ever, comparison of the reported spectral data[77] with those
measured under the same conditions for our sample of 6
(see Figure 1 and the Experimental Section), revealed some
significant differences. First, Ge et al. observed a considera-
1
ble broadening of the H NMR signals, as opposed to the
1
tic of the azide group), a single set of resonances in the H
well-resolved multiplets observed in our case (Figure 1c).
Figure 1. a) ESIMS (H2O/MeOH containing 0.1% HCO2NH4): 1106.2406 [M+NH4]+, 1061.2084 [(MÀN2)+H]+; b) FTIR (thin film); c) 1H NMR spec-
trum (CDCl3) of 6; d) 13C NMR spectrum (CDCl3) of 6; and e) 29Si NMR spectrum (CDCl3) of 6.
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3835

J. L. Chiara et al.
Second, the 13C and 29Si NMR signals of the Si-CH2 moiety
(the most sensitive to cage structure modifications) for our
sample of 6 were observed at d=9.0 and À67.0 ppm, respec-
tively. Ge et al reported that for their product, these signals
were shifted approximately 1 ppm downfield (13C NMR sig-
nals) and 2 ppm upfield (29Si NMR signals) compared with
our data. Moreover, since the authors did not report any
mass spectral data for 6, the identity of their compound
could not be unambiguously ascertained. Most likely, these
substantial spectral differences are a consequence of a struc-
tural divergence between the products prepared by the two
routes. Given the known propensity of POSS cages to suffer
cleavage and rearrangement upon attack by a nucleophile,[78]
it is probable that the azide anion has caused cage expan-
sion (to T10 and T12) or even degradation to a mixture of
oligomers under the harsh thermal conditions (DMF, 1208C,
2 d) employed by the authors in the substitution reaction. In
fact, in an interesting study of cage rearrangements of silses-
quioxanes that included 4, Marsmann and Rikowski[78] ob-
served that the rearrangement of T8 to T10 results in an up-
field shift (approximately 2 ppm) of the 29Si NMR reso-
nance, which is precisely the same shift that was observed
between the sample of 6 prepared by diazo-transfer reaction
(this work) and the data reported by Ge et al. for the prod-
uct obtained through nucleophilic substitution.[79]
Scheme 1. Synthesis of octatriazolyl-POSS compounds 8 by CuAAC reac-
tion of 6 with terminal alkynes.
Since azides are potentially explosive,[80] we evaluated the
safety profile of 6 by differential scanning calorimetry
(DSC) and thermogravimetric analysis (TGA).[81] This study
showed that a slow thermal decomposition of compound 6
started at 2378C, which is well above the temperature re-
quired to perform the thermal cycloadditions (see below),
and no characteristics of explosive behavior were observed.
A weight loss of only about 27% occurred, in approximately
the same temperature range as the DSC exotherm. Thus,
gram quantities of 6 can be safely prepared and stored for
later use without any special precautions.
using phenyl acetylene (7a) as a model, different copper
catalysts and solvent systems were assayed for the synthesis
of the corresponding product 8a (Table 2, entries 1–4). Al-
though all reaction conditions examined afforded excellent
yields of 8a with complete regioselectivity by using a 5%
molar copper catalyst with respect to alkyne, reaction times
varied widely. Slow reactions were observed when the cyclo-
addition was performed at room temperature under homo-
geneous conditions in toluene using the soluble catalysts
(EtO)3P·CuI[82] or the recently described [CuCl
(IPr=N,N’-bis(2,6-diisopropylphenyl)imidazol-2-ylidene)
and [Cu
(C186tren)]Br[85,86] (C186tren=tris(2-dioctadecylami-
noethyl)amine) in the presence of base (Table 2, entries 1–
(IPr)][83,84]
ACHTUNGTRENNUNG
With an optimized procedure for the efficient gram-scale
preparation of 6 in hand, we next studied its octafunctionali-
zation with simple alkynes through CuAAC (Scheme 1). By
AHCTUNGTRENNUNG
Table 2. Synthesis of 8a–h from 6 by CuAAC reaction.
Entry
Alkyne
Catalyst
(EtO)3P·CuI
[CuCl(IPr)]
[Cu(C186tren)]Br
CuSO4·5H2O/sodium ascorbate
CuSO4·5H2O/sodium ascorbate
Base
Solvent (v/v ratio)
T[a] [8C]
t [h]
Product
Yield [%]
1
2
3
4
5
6
7
8
7a
7a
7a
7a
7b
7b
7c
7c
7d
7d
7e
7 f
7 f
7 f
7h
N
iPr2NEt
iPr2NEt
iPr2NEt
none
toluene
toluene
toluene
CH2Cl2/H2O (1:1)
CH2Cl2/H2O (1:1)
toluene
toluene
THF/H2O (2:1)
toluene
THF/H2O (2:1)
toluene
toluene
toluene
CH2Cl2/H2O (1:1)
CH2Cl2/H2O (1:1)
25
25
25
25
70
48
20
1
18
3
3
24
3
24
3
9
3
2
8a
8a
8a
8a
8b
8b
8c
8c
8d
8d
8e
8 f
8 f
8 f
8h
90
90
92
96
61
89
67
77
71
80
88
63
78
85
70
E
R
G
none
25
[Cu
[Cu
[Cu
[Cu
[Cu
[Cu
N
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
iPr2NEt
none
80 (MW)
80 (MW)
25
80 (MW)
25
80 (MW)
80 (MW)
80 (MW)
25
9
10
11
12
13
14
15
T
T
CuSO4·5H2O/sodium ascorbate
CuSO4·5H2O/sodium ascorbate
none
25
4.5
[a] MW indicates that the reaction was conducted by microwave heating.
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Polyhedral Oligosilsesquioxane Frameworks
FULL PAPER
3), with reaction times diminishing in this same order. How-
ever, the fastest reaction and the highest yield (96% isolated
yield, which represents >99% per azide group) was ob-
tained with the CuSO4·H2O/sodium ascorbate precatalyst
system[58] by using a biphasic CH2Cl2/water solvent mix-
ture[87] at room temperature (Table 2, entry 4). The study
was extended to other simple alkynes 7b–e and the process
was found to tolerate a broad range of functional groups
and reaction conditions, affording the corresponding octa-
triazolyl-POSS products 8b--e regioselectively and in good
yield (the lowest yield was 61%, which represents 94% per
azide group). In those cases for which the optimal room
temperature conditions using the CuSO4·H2O/sodium ascor-
bate system resulted in sluggish reactions (Table 2, entry 5),
the soluble copper(I) catalysts performed very efficiently
under microwave heating in homogenous conditions, with
greatly reduced reaction times (Table 2, entries 6, 7, 9, 11–
ly prepared glyco-POSS compounds with model lectins and
the photophysical properties of fluorophore cluster 8h are
currently being evaluated in collaboration with other groups
and will be reported in due course.
Conclusion
We have developed a one-step synthesis of 6 from commer-
cially available 5 by a highly efficient diazo-transfer reaction
under very mild conditions. We have found that nonaflyl
azide is a safer, cheaper, and more efficient diazo-transfer
reagent than the more well known and commonly used trifl-
yl azide. Compound 6, with eight azide groups, is an excel-
lent nanobuilding block that can be efficiently and regiose-
lectively octafunctionalized with a diversity of simple and
complex terminal alkynes through CuAAC reaction under
very mild conditions to provide new functional nanocages 8
in high yield, maintaining a perfect 3D cubic symmetry. A
screening of different CuAAC reaction conditions revealed
that both the CuSO4·5H2O/sodium ascorbate precatalyst
system in aqueous solvents at room temperature and the re-
13). The hexane-soluble [CuACTHNUTRGNE(NUG C186tren)]Br catalyst is particu-
larly attractive in the case of hydrophilic alkynes (Table 2,
entries 7–10), allowing a straightforward workup of the
crude reaction mixture by a simple hexane/MeOH liquid–
liquid extraction, which completely removed the copper cat-
alyst in the hexane fraction, affording the pure product in
the MeOH fraction, free from copper impurities. Moreover,
this was the most efficient of the three soluble copper(I) cat-
alysts tested. As already observed for their precursor 6, all
new octatriazolyl-POSS products 8 prepared in this work
cently described [CuACTHNUTRGNEUNG(C186tren)]Br catalyst in organic sol-
vents under microwave irradiation provided the best yields
and shortest reaction times. The mildness, simplicity, effi-
ciency, and versatility of this approach have been demon-
strated in the preparation of a glyco-POSS conjugate and a
BODIPY–POSS cluster. We believe that this methodology
opens ample possibilities for the efficient and controlled as-
sembly of new hybrid organic/inorganic nanomaterials with
a high degree of symmetry and with carefully tailored func-
tional properties.
1
showed a single set of signals in H and 13C NMR spectra,
and one singlet in the 29Si NMR spectrum,[88] as expected for
a perfect 3D cubic molecular symmetry. The narrow range
of chemical shifts observed for the 29Si NMR signal (d=
À66.6 to À67.4 ppm), which is known to be very sensitive to
cage rearrangements,[78] provided additional proof of the
conserved cubic cage structure of all these new POSS deriv-
atives.
Experimental Section
Armed with the required methodology for the synthesis
of 6 and its efficient derivatization with simple alkynes by
CuAAC reaction, we proceeded to apply it to the prepara-
tion of more complex functional nanoplatforms. The assem-
bly of a multivalent POSS glycoconjugate[61] (8g) and a
POSS-fluorophore cluster[62] (8h) were selected for this
study. Glyco-POSS 8 f was readily assembled from 6 by
CuAAC reaction with acetal-protected propargyl a-d-man-
nopyranoside 7 f[89] under homogenous or biphasic condi-
tions (Table 2, entries 12–14). As observed with the simple
alkynes, the best yield was obtained with CuSO4·5H2O/
sodium ascorbate in a CH2Cl2/H2O mixture at room temper-
ature (Table 2, entry 14). Deprotection of 8 f under mildly
acidic conditions by treatment with trifluoroacetic acid in
THF/H2O (4:1) at room temperature proceeded without af-
fecting the stability of the POSS cage, to afford 8g in 90%
isolated yield. Likewise, reaction of 6 with the ethynylphen-
yl-functionalized boron dipyrromethene (BODIPY) fluores-
cent dye 7h,[90,91] using CuSO4·5H2O/sodium ascorbate in
CH2Cl2/H2O, provided the fluorophore cluster 8h in very
good yield (Table 2, entry 15). The kinetics and thermody-
namics of the complexation reaction of 8g and other similar-
General: All melting points were measured with a Reicher Jung Thermo-
var micro-melting apparatus. Infrared (FTIR) spectra were measured as
KBr pellets or oils between KBr plates by using a Perkin–Elmer Spec-
trum One spectrophotometer and data are reported in cmÀ1 1H and
.
13C NMR spectra were recorded on a BRUKER AMX-300 (300 and
75 MHz, respectively), a Varian INOVA 300 (300 and 75 MHz, respec-
tively), a Varian INOVA 400 (400 and 100 MHz, respectively), or a
Varian UNITY 500 (500 and 125 MHz, respectively) spectrometer.
29Si NMR spectra were measured on a Varian INOVA 400 spectrometer
(79.5 MHz). Chemical shifts are expressed in parts per million (d scale)
downfield from tetramethylsilane and are referenced to residual peaks of
the deuterated solvent used, or to internal tetramethylsilane. Data are
presented as follows: chemical shift, multiplicity (s=singlet, d=doublet,
t=triplet, m=multiplet and/or multiple resonances, br=broad), integra-
tion, coupling constants in hertz (Hz), and assignment. 1H and 13C NMR
assignments are based on DQ-COSY, HSQC, and HMBC correlation ex-
periments. TLC was performed with Merck Silica Gel 60 F254 plates.
Chromatograms were visualized by using UV light and/or treatment with
a solution of ammonium molybdate (50 g) and cerium(IV) sulfate (1 g) in
5% aqueous H2SO4 (1 L), followed by charring on a hot plate. For detec-
tion of azides, the chromatograms were first dipped in a 1% (w/v) solu-
tion of Ph3P in EtOAc, dried at RT, then dipped in a 1% or 5% (w/v) so-
lution of ninhydrin in 95% aqueous EtOH, and finally charred on a hot
plate.[92] Column chromatography was performed with Merck silica gel,
grade 60, 230–400 mesh. Mass spectra were recorded on a MALDI Voy-
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3837

J. L. Chiara et al.
ager-DE PRO time-of-flight (TOF) spectrometer (Applied Biosystems),
using a 2,5-dihydroxybenzoic acid matrix, or in an Agilent/HP 1100 LC/
MSD spectrometer using ESI or APCI sources. High-resolution mass
spectra were recorded on an Agilent 6520 Q-TOF instrument with a ESI
source. Elemental analyses were determined by using a Heraus CHN-O
analyser. Anhydrous solvents were prepared according to standard meth-
ods by distillation over drying agents or elution through a Pure Solv
column drying system,[93] obtained from Innovative Technology, Inc. All
other solvents were of HPLC grade and were used as provided. All reac-
tions were carried out with magnetic stirring and, if air or moisture sensi-
tive, in oven-dried glassware under argon. Microwave irradiation experi-
ments were performed with a single-mode Discover System from CEM
Corporation, using standard Pyrex tubes (10 or 35 mL capacity) sealed
(SiCH2CH2CH2N3); 29Si NMR (79.5 MHz, CDCl3): d=À67.0 ppm; MS
(API-ESI): m/z (%): 1112 [M+Na+]; HRMS (ESI): m/z calcd for
C24H52N25O12Si8: 1106.2381 [M+NH4+]; found: 1106.2396.
Octakis[3-(4’-phenyl-1’H-1’,2’,3’-triazol-1’-yl)propyl]octasilsesquioxane
(8a)
Method A: (EtO)3P·CuI (3 mg, 0.008 mmol) and iPr2NEt (66 mL,
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and phe-
nylacetylene (20 mL, 0.182 mmol) in toluene (1 mL) under argon. After
stirring for 70 h at RT, the solvent was removed under reduced pressure,
the crude product was dissolved in CH2Cl2, and the product was precipi-
tated with Et2O to afford 8a (30 mg, 90%) as a white powder.
Method B: [CuClACHTNUGTRNEUNG(IPr)] (3 mg, 0.009 mmol) and iPr2NEt (66 mL,
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and phe-
nylacetylene (20 mL, 0.182 mmol) in toluene (1 mL) under argon. After
stirring for 48 h at RT, the solvent was removed under reduced pressure,
the crude product was dissolved in CH2Cl2, and the product was precipi-
tated with Et2O to afford 8a (30 mg, 90%) as a white powder.
with a rubber cap. The copper(I) catalysts (EtO)3P·CuI,[94] [CuCl
(IPr=N,N’-bis(2,6-diisopropylphenyl)imidazol-2-ylidene),[95] and [Cu-
(C186tren)]Br[85] (C186tren=tris(2-dioctadecylaminoethyl)amine) were
ACHTUNGTRNE(NUNG IPr)]
ACHTUNGTRENNUNG
prepared following described procedures.
Octakis(3-azidopropyl)octasilsesquioxane (6)
Method C: [CuACHTUNTRGNEUNG(C186tren)]Br (17 mg, 0.009 mmol) and iPr2NEt (66 mL,
Method A: With triflyl azide: a) Synthesis of a solution of triflyl azide in
toluene:[76] Toluene (2.6 mL) was added to a solution of sodium azide
(1.06 g, 16.32 mmol) in water (2.6 mL), and the mixture was cooled to
08C. Triflic anhydride (1.4 mL, 8.16 mmol) was then added dropwise with
vigorous stirring (30 min addition time) and the stirring was continued
for 2 h at 108C. A saturated aqueous solution of NaHCO3 was added
dropwise until gas evolution had ceased, and the two phases were sepa-
rated. The aqueous layer was extracted with toluene (2ꢄ2.6 mL). The
combined organic layers containing trifyl azide were used in the subse-
quent diazo-transfer reaction. b) Diazo-transfer reaction: The previously
prepared stock solution of triflyl azide (7.8 mL), then iPrOH (11 mL)
were added sequentially to a solution of 5·8HCl[21] (200 mg, 0.22 mmol),
NaHCO3 (592 mg, 7.04 mmol), and CuSO4·5H2O (4 mg, 0.34 mmol) in
water (0.2 mL) at 08C. After vigorously stirring the resulting homogene-
ous mixture at RT for 12 h, the mixture was concentrated under reduced
pressure, and the crude product was partitioned between EtOAc (25 mL)
and a saturated aqueous solution of ethylenediaminetetraacetic acid
(EDTA, 15 mL). The phases were separated, the aqueous solution was
extracted with EtOAc (3ꢄ10 mL), the combined organic layers were
washed with brine, dried (Na2SO4), and the solvent was removed under
reduced pressure. The residue was purified by flash column chromatogra-
phy (hexane/EtOAc 15:1) to obtain 6 as a colorless viscous oil (130 mg,
54%). When this reaction was run with 1.0–2.0 g of starting octaamino-
POSS 5, the yield dropped to 30–32%.
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and phe-
nylacetylene (20 mL, 0.182 mmol) in toluene (1 mL) under argon. After
stirring for 20 h at RT, the solvent was removed under reduced pressure,
the crude product was dissolved in CH2Cl2, and the product was precipi-
tated with Et2O to afford 8a (31 mg, 92%) as a white powder.
Method D: A solution of CuSO4·5H2O (2.5 mg, 0.010 mmol) and sodium
ascorbate (9 mg, 0.045 mmol) in water (0.5 mL) were added to a solution
of 6 (20 mg, 0.018 mmol) and phenylacetylene (20 mL, 0.182 mmol) in
CH2Cl2 (0.5 mL). After stirring for 1 h at RT, a saturated aqueous solu-
tion of EDTA (1 mL) was added, the mixture was vigorously stirred for
30 min, the phases were separated, and the aqueous layer was extracted
with CH2Cl2 (2ꢄ5 mL). The combined organic layers were dried over
Na2SO4, the solvent was removed under reduced pressure, the crude
product was dissolved in CH2Cl2, and the product was precipitated with
Et2O to afford 8a (33 mg, 96%) as a white powder. M.p. (Et2O) 207–
2098C; 1H NMR (400 MHz, CDCl3): d=0.61–0.65 (m, 16H; SiCH2),
2.00–2.04 (m, 16H; SiCH2CH2), 4.35 (t, 16H, J=6.7 Hz;
SiCH2CH2CH2N3), 7.26–7.38 (m, 24H; Ar), 7.82 (d, 16H, J=7.4 Hz; Ar),
7.95 ppm (s, 8H; 1,2,3-triazole); 13C NMR (100 MHz, CDCl3): d=8.8
(SiCH2), 24.7 (SiCH2CH2), 52.4 (SiCH2CH2CH2N3), 120.4 (CH; 1,2,3-tria-
zole), 125.8 (2CH; Ph), 128.3 (CH; Ph), 129.0 (2CH; Ph), 130.8 (C; Ph),
148.1 ppm (C, 1,2,3-triazole); 29Si NMR (79.5 MHz, CDCl3): d=
À67.2 ppm; HRMS (ESI): m/z calcd for C88H97N22O12Si8: 1905.5872
[M+H+]; found: 1905.5816.
Method B: With nonaflyl azide: a) Synthesis of nonaflyl azide:[73] Nona-
fluorobutanesulfonyl fluoride (20 mL, 111 mmol) was added to a solution
of NaN3 (8.0 g, 123 mmol) in MeOH (220 mL). After stirring at 208C for
12 h, the mixture was poured onto ice–water. If a stable emulsion was
formed, which was broken by filtration through a layer of Na2SO4 to give
two layers. The colorless oily layer of nonafluorobutanesulfonyl azide
was separated, dried over Na2SO4, and used without further purification
for the diazo-transfer reaction (22 g, 60%). The pure reagent can be kept
at 48C for several weeks without decomposition. b) Diazo-transfer reac-
Octakis[(3-
yl)propyl)]octasilsesquioxane (8b)
Method C: [Cu(C186tren)]Br (17 mg, 0.009 mmol) and iPr2NEt (66 mL,
ACHTUNGTNER(NUNG 4’-((1’’,3’’-dioxoisoindolin-2’’-yl)methyl)-1’H-1’,2’,3’-triazol-1’-
AHCTUNGTRENNUNG
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and N-
propargylphthalimide (33 mg, 0.178 mmol) in toluene (1 mL) under
argon. After heating for 3 h at 808C under microwave irradiation, a
white precipitate was formed. The reaction mixture was dissolved in
MeOH and the product was precipitated with CHCl3 to afford 8b as a
white powder (34.2 mg, 74%).
tion: EtOH (90 mL),
(13.30 g, 40.9 mmol) in Et2O (30 mL),
a
solution of nonafluorobutanesulfonyl azide
solution of CuSO4·5H2O
a
Method D: A solution of CuSO4·5H2O (2.5 mg, 0.010 mmol) and sodium
(213 mg, 0.852 mmol) in water (2 mL), and a solution of NaHCO3 (4.58 g,
54.6 mmol) in water (26 mL) were added sequentially to a solution of
5·8HCl[21] (2.0 g, 1.70 mmol) in water (2 mL) at 08C. The reaction mix-
ture was vigorously stirred at 08C for 1 h, and at RT for 24 h. The mix-
ture was concentrated under reduced pressure, CH2Cl2 (150 mL) was
added, and the resultant solution was washed with a saturated aqueous
solution of NaHCO3 (4ꢄ100 mL) to remove the nonafluorobutanesulfo-
namide. The organic layer was separated, dried over Na2SO4, and concen-
trated under reduced pressure. The residue was purified by flash column
chromatography (hexane/EtOAc 15:1) to afford 6 as a colorless viscous
oil (1.250 g, 67%). Rf =0.6 (silica gel, hexane/EtOAc 5:1), IR (film): n=
ascorbate (9 mg, 0.045 mmol) in water (1 mL) were added to a solution
of
6
(20 mg, 0.018 mmol) and N-propargylphthalimide (33 mg,
0.178 mmol) in CH2Cl2 (1 mL). After stirring for 18 h at RT, a saturated
aqueous solution of EDTA (1 mL) was added, the mixture was vigorous-
ly stirred for 30 min, the phases were separated, and the aqueous layer
was extracted with CH2Cl2 (2ꢄ5 mL). The combined organic layers were
dried over Na2SO4, the solvent was removed under reduced pressure, the
crude product was dissolved in MeOH, and the product was precipitated
with CHCl3 to afford 8b as a white powder (28 mg, 61%). M.p. (CHCl3)
163–1668C; 1H NMR (400 MHz, [D6]DMSO): d=0.46–0.50 (m, 16H;
SiCH2), 1.74–1.78 (m, 16H; SiCH2CH2), 4.21 (t, 16H, J=6.7 Hz;
SiCH2CH2CH2), 7.77–7.83 (m, 32H; Ar), 8.03 ppm (s, 8H; 1,2,3-triazole);
13C NMR (100 MHz, [D6]DMSO): d=7.9 (SiCH2), 23.3 (SiCH2CH2), 32.9
(CH2N-phthalimido), 51.2 (SiCH2CH2CH2), 123.1 (CH, 1,2,3-triazole;
2CH; phthalimido), 131.5 (2C; phthalimido), 134.4 (2CH; phthalimido),
2939, 2875, 2099 (s; N3), 1304, 1278, 1243, 1188, 1111 (s), 699 cmÀ1
;
1H NMR (300 MHz, CDCl3) d=0.46–1.00 (m, 16H; SiCH2), 1.42–1.99
(m, 16H; SiCH2CH2), 3.28 ppm (t, 16H, J=6.9 Hz; SiCH2CH2CH2N3);
13C NMR (100 MHz, CDCl3): d=9.0 (SiCH2), 22.5 (SiCH2CH2), 53.4 ppm
3838
www.chemeurj.org
ꢃ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2010, 16, 3833 – 3841

Polyhedral Oligosilsesquioxane Frameworks
FULL PAPER
142.2 (C; 1,2,3-triazole), 167.2 ppm (C=O; phthalimido); 29Si NMR
(79.5 MHz, [D6]DMSO): d=À66.6 ppm; HRMS (ESI): m/z calcd for
Method C: [CuACHTUGNTERNNU(G C186tren)]Br (43 mg, 0.024 mmol) and iPr2NEt (135 mL,
0.775 mmol) were added to a solution of 6 (51 mg, 0.047 mmol) and 7 f[89]
(144 mg, 0.483 mmol) in toluene (5 mL) under argon. After stirring for
8 h at 808C under microwave irradiation, a white precipitate was formed.
The solvent was removed under reduced pressure and the residue was
purified by flash column chromatography (CH2Cl2/MeOH 10:1) to afford
8 f as a white powder (127 mg, 78%).
C
112H105N32O28Si8: 2569.5930 [M+H+]; found: 2569.5841.
Octakis[(3-ACHTUNGTRENNUNG(4’-(hydroxymethyl)-1’H-1’,2’,3’-triazol-1’-yl)propyl)]octasilses-
quioxane (8c)
Method C: [CuACHTUNGTRENNUNG(C186tren)]Br (17 mg, 0.009 mmol) and iPr2NEt (66 mL,
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and prop-
argyl alcohol (11 mL, 0.189 mmol) in toluene (1.0 mL) under argon. After
heating for 3 h at 808C under microwave irradiation, a white precipitate
was formed. The precipitate was dissolved in MeOH (2 mL), the solution
was extracted with hexane (3ꢄ3 mL), and the methanol layer was con-
centrated under reduced pressure to afford 8c as a colorless oil (18.5 mg,
67%). Using THF/H2O (2:1) instead of toluene in this procedure gave
8c in 77% yield, after stirring the reaction for 25 h at RT. 1H NMR
(400 MHz, CD3OD): d=0.59–0.63 (m, 16H; SiCH2), 1.92–1.98 (m, 16H;
SiCH2CH2), 4.39 (t, 16H, J=6.8 Hz; SiCH2CH2CH2), 4.69 (s, 16H;
CH2OH), 7.93 ppm (s, 8H; 1,2,3-triazole); 13C NMR (100 MHz, CD3OD):
d=9.5 (SiCH2), 25.2 (SiCH2CH2), 53.4 (SiCH2CH2CH2), 56.6 (CH2OH),
124.5 (CH; 1,2,3-triazole), 149.2 ppm (C; 1,2,3-triazole); HRMS (ESI):
m/z calcd for C48H81N24O20Si8: 1537.4213 [M+H+]; found: 1537.4253.
Method D: A solution of CuSO4·5H2O (2.5 mg, 0.010 mmol) and sodium
ascorbate (9 mg, 0.045 mmol) in water (0.5 mL) was added to a solution
of
6
(20 mg, 0.018 mmol) and 7 f[89] (53 mg, 0.178 mmol) in CH2Cl2
(0.5 mL). After stirring for 2 h at RT, a saturated aqueous solution of
EDTA (1 mL) was added, the mixture was vigorously stirred for 30 min,
the phases were separated, and the aqueous layer was extracted with
CH2Cl2 (2ꢄ2 mL). The organic layers were combined, dried over
Na2SO4, and the solvent was removed under reduced pressure. The crude
product was purified by flash column chromatography (CH2Cl2/MeOH
10:1) to afford 8 f as a white powder (53 mg, 85%). M.p. (CH2Cl2) 118–
1228C; 1H NMR (400 MHz, CDCl3): d=0.57–0.61 (m, 16H; Si-
CH2CH2CH2), 1.25 (s, 24H; C
N
ACHTUGNTREN(UNNG CH3)2), 1.45 (s,
24H; (CH3)2), 1.47 (s, 24H;
C
N
CACHTUNGTRENNUNG
SiCH2CH2CH2), 3.51–3.60 (m, 8H; H-5’’), 3.66–3.67 (m, 8H; H-4’’), 3.70
(t, 8H, J=10.5 Hz; H-6a’’), 3.82 (dd, 8H, J=5.6, 10.5 Hz; H-6b’’), 4.05
(dd, 8H, J=5.4, 7.8 Hz; H-3’’), 4.11 (d, 8H, J=5.4 Hz; H-2’’), 4.27 (t,
16H, J=7.1 Hz; SiCH2CH2CH2), 4.60 (d, 8H, J=12.2 Hz; CH2O-C-1’’),
4.77 (d, 8H, J=12.2 Hz; CH2O-C-1’’), 5.09 (s, 1H; H-1’’), 7.72 ppm (s,
8H; CH of 1,2,3-triazole); 13C NMR (100 MHz, CDCl3): d=8.9
Octakis[3-ACHTUNGTRENNUNG(4’-(4’’-hydroxybutyl)-1’H-1’,2’,3’-triazol-1’-yl]propyl)silses-
quioxane (8d)
Method C: [CuACHTUNGTRENNUNG(C186tren)]Br (17 mg, 0.009 mmol) and iPr2NEt (66 mL,
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and 5-
hexyn-1-ol (21 mL, 0.190 mmol) in toluene (1 mL), under argon. After
heating for 3 h at 808C under microwave irradiation, a white precipitate
was formed. The precipitate was dissolved in MeOH (2 mL), the solution
was extracted with hexane (3ꢄ5 mL), and the methanol layer was con-
centrated under reduced pressure to afford 8d (24 mg, 71%) as a color-
less oil. Using THF/H2O (2:1) instead of toluene in this procedure gave
8d in 80% yield after stirring the reaction for 25 h at RT. 1H NMR
(400 MHz, [D6]DMSO): d=0.45 (brs, 16H; SiCH2), 1.39–1.47 (m, 16H;
CH2CH2CH2CH2OH), 1.53–1.63 (m, 16H; CH2CH2CH2CH2OH), 1.75
(brs, 16H; SiCH2CH2), 2.55–2.60 (m, 16H; CH2CH2CH2CH2OH), 3.37
(brs, 16H; CH2CH2CH2CH2OH), 4.22 (brs, 16H; SiCH2CH2CH2), 4.39
(brs, 16H; CH2CH2CH2CH2OH), 7.79 ppm (s, 8H; 1,2,3-triazole);
13C NMR (100 MHz, [D6]DMSO): d=9.2 (SiCH2; data obtained from the
HSQC spectrum), 24.1 (SiCH2CH2), 25.5 (CH2CH2CH2CH2OH), 26.3
(SiCH2CH2CH2), 19.0 (C
28.4 (C(CH3)2), 29.3 (C(CH3)2), 52.4 (SiCH2CH2CH2), 60.5 (CH2O-C-1’’),
61.8 (C-5’’), 62.2 (C-6’’), 72.8 (C-4’’), 75.0 (C-3’’), 76.1 (C-2’’), 97.2 (C-1’’),
CAHTUTGNRENG(UN CH3)2), 24.2 (SiCH2CH2CH2), 26.4 (CACHTUNGTRENNUNG(CH3)2),
A
ACHTUNGTRENNUNG
99.9 (CACTHNUTRGENNUG(CH3)2), 109.7 (CAHCUTNTGERN(NUGN CH3)2), 123.6 (CH of 1,2,3-triazole), 143.9 ppm
(C of 1,2,3-triazole); 29Si NMR (79.5 MHz, CDCl3): d=À67.3 ppm; MS
(MALDI-TOF; 2,5-dihydroxybenzoic acid matrix): m/z: 3496 [M+Na+];
HRMS (ESI): m/z calcd for C144H226N24O60Si8: 1737.6762 [(M+2H)2+];
found: 1737.6858.
Octakis{3-ACTHUNRTGNEUNG[4’-((a-d-mannopyranos-1’-yl)methyl)-1’H-1’,2’,3’-triazol-1’-yl]-
propyl}octasilsesquioxane (8g): Trifluoroacetic acid (25 mL, 0.324 mmol)
was added to a solution of 8 f (54 mg, 0.015 mmol) in THF/H2O (4:1)
(2 mL). After stirring for 3 h at RT, compound 8g was isolated as a white
precipitate (38 mg, 90%), m. p. (H2O) 112–1168C; 1H NMR (500 MHz,
D2O): d=0.32–0.44 (m, 16H; Si-CH2CH2CH2), 1.74–1.78 (m, 16H;
SiCH2CH2CH2), 3.47–3.78 (m, 48H; H-2’’, H-3’’, H-4’’, H-5’’, H-6a’’, and
H-6b’’), 4.14–4.30 (m, 16H; SiCH2CH2CH2), 4.61–4.68 (m, 16H;
CH2CCH), 4.80 (s, 8H; H-1’’), 7.90 ppm (brs, 8H; 1,2,3-triazole); 13C
NMR (125 MHz, [D6]DMSO): d=10.7 (SiCH2CH2CH2; data obtained
from HSQC spectrum), 25.2 (SiCH2CH2CH2), 53.46 (SiCH2CH2CH2),
61.0 (OCH2-triazole), 62.3 (C-6’’), 68.1 (C-4’’), 71.4 (C-2’’), 71.9 (C-3’’),
74.5 (C-5’’), 100.7 (C-1’’), 126.4 (CH in triazole), 145.0 ppm (C in tria-
zole); MS (MALDI-TOF, 2,5-dihydroxybenxoic acid matrix): m/z: 2855
[M+Na]+; HRMS (ESI): m/z: calcd for C97H161N23NaO60Si8: 2855.8258
[M+Na]+; found: 2855.8253.
(CH2CH2CH2CH2OH),
32.7
(CH2CH2CH2CH2OH),
51.7
(SiCH2CH2CH2), 61.1 (CH2CH2CH2CH2OH), 122.3 (CH; 1,2,3-triazole),
147.6 ppm (C; 1,2,3-triazole); HRMS (ESI): m/z calcd for
C72H129N24O20Si8: 1873.7969 [M+H+]; found: 1873.7951.
Octakis[3-
sesquioxane (8e)
Method C: [Cu(C186tren)]Br (17 mg, 0.009 mmol) and iPr2NEt (66 mL,
ACHTUNGTRENNUNG(4’-(methoxycarbonyl)-1’H-1’,2’,3’-triazol-1’-yl)propyl]octasil-
ACHTUNGTRENNUNG
0.378 mmol) were added to a solution of 6 (20 mg, 0.018 mmol) and
methyl propiolate (16 mL, 0.180 mmol) in toluene (1 mL) under argon.
After heating for 8 h at 808C under microwave irradiation, a white pre-
cipitate was formed. The reaction mixture was dissolved in MeOH and
the product was precipitated by addition of CHCl3 to afford 8e (28 mg,
88%) as a white powder. M.p. (CHCl3) 125–1278C; 1H NMR (400 MHz,
CDCl3): d=0.54–0.59 (m, 16H; SiCH2), 1.97–2.02 (m, 16H; SiCH2CH2),
3.93 (s, 24H; COOCH3), 4.42 (t, 16H, J=6.7 Hz; SiCH2CH2CH2),
8.24 ppm (s, 8H; 1,2,3-triazole); 13C NMR (100 MHz, CDCl3): d=8.3
(SiCH2), 23.7 (SiCH2CH2), 52.2 (SiCH2CH2CH2), 52.4 (COOCH3), 127.9
(CH; 1,2,3-triazole), 139.8 (C; 1,2,3-triazole), 161.1 ppm (COOCH3);
29Si NMR (79.5 MHz, CDCl3) d=À67.4 ppm; HRMS (ESI): m/z calcd
for C56H81N24O28Si8: 1761.3806 [M+H+]; found: 1761.3796.
Octakis(3-ACTHNUGTRENNUG{4’-CAHTUNGTREN[NUNG 4”-(2’’’,8’’’-diethyl-5’’’,5’’’-difluoro-1’’’,3’’’,7’’’,9’’’-tetramethyl-
dipyrrolo[1’’’,2’’’c:2’’’,1’’’f][1’’’,3’’’,2’’’]diazaborinin-4’’’-ium-5’’’-uid-10’’’-yl)-
phenyl]-1’H-1’,2’,3’-triazol-1’-yl}propyl)octasilsesquioxane (8h)
Method D: A solution of CuSO4·5H2O (2.5 mg, 0.010 mmol) and sodium
ascorbate (9 mg, 0.045 mmol) in water (0.6 mL) was added to a solution
of 6 (20 mg, 0.018 mmol) and 8h[90] (72 mg, 0,178 mmol) in CH2Cl2
(0.9 mL). After stirring for 4.5 h at RT, a saturated aqueous solution of
EDTA (1 mL) was added, the mixture was vigorously stirred for 30 min,
the phases were separated, and the aqueous layer was extracted with
CH2Cl2 (2ꢄ3 mL). The organic layers were combined, dried over
Na2SO4, and the solvent was removed under reduced pressure. The crude
product was purified by flash column chromatography (hexane/EtOAc
5:1) to afford 8h as a red powder (54 mg, 70%). M.p. (CH2Cl2) 2908C
Octakis{3-ACHTUNGTRENNUNG[4’-((2’’,3’’,4’’,6’’-di-O-isopropylidene-a-d-mannopyranos-1’’-yl)-
methyl)-1’H-1’,2’,3’-triazol-1’-yl]propyl}octasilsesquioxane (8 f)
Method A: (EtO)3P·CuI (5 mg, 0.014 mmol) and iPr2NEt (91 mL,
0.522 mmol) were added to a solution of 6 (35 mg, 0.032 mmol) and 7 f[89]
(86 mg, 0.288 mmol) in THF (1 mL) under argon. After stirring for 9 h at
808C under microwave irradiation, the solvent was removed under re-
duced pressure and the residue was purified by flash column chromatog-
raphy (CH2Cl2/MeOH 10:1) to afford 8 f as a white powder (70 mg,
63%).
1
(decomposition); H NMR (400 MHz, CDCl3): d=0.68–0.75 (m, 16H; Si-
CH2CH2CH2), 0.93 (t, 48H, J=7.4 Hz; 16ꢄ(CH3CH2), 1.30 (s, 48H; 16ꢄ
CH3-C), 2.13–2.18 (m, 16H; SiCH2CH2CH2), 2.25 (q, 32H, J=7.4 Hz;
16ꢄCH2CH3), 2.51 (s, 48H; 16ꢄCH3-C), 4.46 (t, 16H, J=6.9 Hz;
SiCH2CH2CH2), 7.32 (d, 16H, J=8.2 Hz; 2ꢄCH Ar), 8.01 (d, 16H, J=
Chem. Eur. J. 2010, 16, 3833 – 3841
ꢃ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
3839

J. L. Chiara et al.
8.2; 2ꢄCH Ar), 8.15 ppm (s, 8H; 1,2,3-triazole); 13C NMR (100 MHz,
CDCl3): d=8.7 (SiCH2CH2CH2), 11.9 (CH3), 12.5 (CH3), 14.6 (CH3-
CH2), 17.0 (CH3-CH2), 24.1 (SiCH2CH2CH2), 52.4 (SiCH2CH2CH2), 120.7
(CH in 1,2,3-triazole), 126.1 (Ph), 129.0 (Ph), 130.1, 131.2, 133.1, 135.8,
137.9, 139.2 (C in 1,2,3-triazole), 147.1, 154.0 ppm; 29Si NMR (79.5 MHz,
CDCl3) d=À67.1 ppm; MS (MALDI-TOF, 2,5-dihydroxybenzoic acid
matrix): m/z: 4304 [MÀF]+.
[23] D. Herren, H. Buergy, G. Calzaferri, Helv. Chim. Acta 1991, 74, 24–
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Chem. Eur. J. 2010, 16, 3833 – 3841

Polyhedral Oligosilsesquioxane Frameworks
FULL PAPER
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Received: September 1, 2009
Published online: February 16, 2010
Chem. Eur. J. 2010, 16, 3833 – 3841
ꢃ 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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