Diversified strategies for the synthesis of bifunctional dendrimeric structures

Article abstract of DOI:10.1002/ejoc.201300456

The synthesis of three new families of dendrimeric compounds possessing two different types of functions is reported. These functions are triethoxysilyl group(s), potentially suitable for grafting onto materials, in particular silica, and primary amines (in their protected form), potentially suitable for trapping CO₂. All these dendrimeric compounds are based on phosphorus dendrimers, and possess either one Si(OEt)₃ group at the core of dendrons or of off-centre dendrimers, or several Si(OEt)₃ groups precisely placed on half of the terminal groups. These compounds are characterized by ³¹P NMR spectroscopy, which affords precious information on the structure, confirmed, in one case, by the X-ray diffraction structure of a first-generation dendrimer. The synthesis of three families of new, bifunctional dendrimeric compounds is reported. The types of functional groups used here are particularly suitable for grafting these compounds onto materials, but the strategies elaborated for their syntheses are potentially useful for many different types of couples of functional groups. Copyright

Full text of DOI:10.1002/ejoc.201300456

Job/Unit: O30456
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Date: 09-07-13 16:51:25
Pages: 10
FULL PAPER
Dendrimer Synthesis
D. Riegert, A. Pla-Quintana, S. Fuchs,
R. Laurent, C.-O. Turrin, C. Duhayon,
J.-P. Majoral, A. Chaumonnot,*
A.-M. Caminade* ........................... 1–10
The synthesis of three families of new, bi-
functional dendrimeric compounds is re-
ported. The types of functional groups
used here are particularly suitable for graft
ing these compounds onto materials, but
the strategies elaborated for their syntheses
are potentially useful for many different
types of couples of functional groups.
Diversified Strategies for the Synthesis of
Bifunctional Dendrimeric Structures
Keywords: Dendrimers / Phosphorus / Pro-
tecting groups / Amines
0000, 0–0
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Job/Unit: O30456
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Date: 09-07-13 16:51:25
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A.-M. Caminade et al.
FULL PAPER
DOI: 10.1002/ejoc.201300456
Diversified Strategies for the Synthesis of Bifunctional Dendrimeric Structures
David Riegert,[a,b,c] Anna Pla-Quintana,[a,b] Sabine Fuchs,[a,b] Régis Laurent,[a,b]
Cédric-Olivier Turrin,[a,b] Carine Duhayon,[a,b] Jean-Pierre Majoral,[a,b]
Alexandra Chaumonnot,*[c] and Anne-Marie Caminade*[a,b]
Keywords: Dendrimers / Phosphorus / Protecting groups / Amines
The synthesis of three new families of dendrimeric com-
pounds possessing two different types of functions is re-
ported. These functions are triethoxysilyl group(s), poten-
tially suitable for grafting onto materials, in particular silica,
and primary amines (in their protected form), potentially suit-
able for trapping CO2. All these dendrimeric compounds are
based on phosphorus dendrimers, and possess either one Si-
(OEt)3 group at the core of dendrons or of “off-centre” den-
drimers, or several Si(OEt)3 groups precisely placed on half
of the terminal groups. These compounds are characterized
by 31P NMR spectroscopy, which affords precious information
on the structure, confirmed, in one case, by the X-ray diffrac-
tion structure of a first-generation dendrimer.
Among the different types of dendrimers, phosphorus-
containing dendrimers [poly(phosphorhydrazone) dendri-
Introduction
Dendrimers[1] are perfectly defined macromolecules con- mers][8] are perfectly suited for the elaboration of bifunc-
stituted of branching units emanating radially from a cen- tional compounds, as already demonstrated in the synthesis
tral core. Depending mainly on the nature of their terminal of dendrons,[9] of Janus dendrimers,[6] for the post-function-
groups, they have found uses in many different fields, and alization of the internal structure,[10] including new
in particular for catalysis, for the elaboration or modifica- branches,[11] or for the selective grafting of two[12] (or
tion of materials, and for various biomedical uses.[2] In most more)[13] functions on each terminal group. However, in
cases dendrimers and dendrimeric structures have numer- many cases, only one type of function is potentially suitable
ous but identical terminal groups. However, the demand on for undergoing further reactions. Furthermore, if precise
their structural complexity is increasing,[3] and there is a functions are needed for particular purposes, these strate-
real need for elaborating strategies toward bifunctional den- gies have to be adapted, improved, or totally changed.
drimers. Among dendrimeric compounds, dendrons (den-
drimeric wedges)[4] have one function at the core and several
other functions as terminal groups,[5] but either one or the
other functions are often poorly reactive. Other strategies,
often based on the association of two dendrons by their
core, lead to “Janus” dendrimers (two different functions
located on two faces),[6] but here again one of these func-
tions is often poorly or non-reactive, for instance fluores-
cent groups. Finally, two (or more) different functions can
be grafted statistically onto the surface of dendrimers,[7] but
in this case, the resulting compound is not well defined.
Our aim here was to elaborate bifunctional dendrimeric
structures potentially suitable for grafting to silica with a
view to using the resulting functionalized materials for
trapping CO2, through its reaction with amines (also per-
taining to the dendrimeric compound), to form carb-
amates.[14] Trapping and efficiently storing CO2, especially
at low concentration, is a huge challenge, with respect to
the global warming problem. Gathering several amines in a
single dendrimeric compound might be helpful for increas-
ing the trapping efficiency. Thus, suitable dendrimeric com-
pounds for such a purpose should have one (or a few) func-
tions useful for grafting to silica, most preferably the classi-
cal triethoxysilyl group, and several amines, preferably pro-
[a] Laboratoire de Chimie de Coordination du CNRS,
205 route de Narbonne, BP 44099, 31077 Toulouse Cedex 4, tected, to avoid premature trapping of CO2 during the syn-
France
thetic process and storage. To fulfill these requirements, we
E-mail: caminade@lcc-toulouse.fr
have designed, as target compounds, the structures shown
in Figure 1, a dendron (A), an “off-centre”[15] dendrimer
(B), and a multi-bifunctional dendrimer (C). In all cases we
have focused our attention on relatively small dendrimeric
compounds to retain the reactivity of the Si(OEt)3 group
that should not be screened by the bulky dendrimeric struc-
ture.
Homepage: http://www.lcc-toulouse.fr/lcc/spip.php?article26
[b] Université de Toulouse, UPS, INPT,
31077 Toulouse Cedex 4, France
[c] IFPEN, Rond point de l’échangeur de Solaize,
BP 3, 69360 Solaize, France
E-mail: alexandra.chaumonnot@ifpen.fr
Homepage: http://www.ifpenergiesnouvelles.com
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201300456.
2
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Synthesis of Bifunctional Dendrimeric Structures
having a vinyl group at the core, and P(S)Cl2 terminal func-
tions (two for first-generation 1-G1, four for second-genera-
tion 1-G2). The full synthetic pathway was tested with the
a first-generation compound. The first step is to graft the
protected amino terminal groups onto dendron 1-G1. We
used Boc-protected tyramine in which the phenol reacts
with the P(S)Cl2 functions under basic conditions to afford
dendron 2-G1. The completion of the reaction is shown by
31P NMR spectroscopy, which displays first the appearance
of a new singlet at δ ≈ 69 ppm corresponding to the mono-
substitution [P(S)Cl(OAr)], then the disappearance of this
intermediate signal with appearance of a new singlet at δ =
62.8 ppm corresponding to disubstitution [P(S)(OAr)2]. The
second step is the addition of aminopropyltriethoxysilane
to the vinyl group at the core of the dendron, activated by
the presence of the P=N–P=S linkage,[17] to afford com-
pound 3-G1 (Scheme 1). The completion of this reaction is
Figure 1. The type of bifunctional dendrimeric compounds tar-
geted.
We report here the synthesis of the three types of den-
drimeric molecules shown in Figure 1, based on phosphor-
hydrazones as building blocks for the internal structure. We
also report some structural features detected by 31P NMR
spectroscopy and confirmed by X-ray diffraction analysis
of a first-generation dendrimer.
Results and Discussion
1
easily detected both by H and 31P NMR spectroscopy. In
1H NMR spectrum, the ABC system corresponding to the
vinyl group disappears. In 31P NMR spectrum, the chemical
shift of the doublet corresponding to the P=N group of the
P=N–P=S linkage is shifted, from δ = 11.2 ppm for 2-G1 to
δ = 17.4 ppm for 3-G1.
The same type of experiment was then carried out for
the second-generation, under the same conditions, affording
dendrons 2-G2 then 3-G2 (Figure 2). Larger compounds
could be synthesized, but the accessibility to the core would
be more difficult to ascertain. Dendrons 3-Gn (n = 1, 2)
possess one triethoxysilyl group and 4, or 8 protected
amines. These are the first type of dendrimeric molecules
potentially suitable for grafting onto silica (Figure 1, A).
Dendrimers having a single triethoxysilyl function at the
The phosphorhydrazone dendrimers and dendrons that
we synthesize have either aldehydes or P(S)Cl2 terminal
groups; both react readily with amines, thus it is impossible
to graft directly primary amines as terminal groups for
these dendrimeric compounds. Furthermore, to avoid the
unwanted trapping of CO2 during synthesis, we chose tert-
butyloxycarbonyl (Boc)-protected tyramine or Boc-mono-
protected ethylenediamine, with the aim of using either the
phenol or the remaining free amine for grafting to the P(S)-
Cl2 terminal groups. We choose the propyltriethoxysilyl
group for grafting to silica, with the propyl group being
functionalized either by a NH2 or a N=C=O group, for
grafting to the dendrimeric structure.
In the case of the dendrons (Figure 1, type A), we applied
a strategy already reported, but with a different type of ter- core (Figure 1, “off-centre” type B) are synthesized by using
minal function.[16] The starting compound is dendron 1-Gn the known possibility to react only one Cl of N3P3Cl6.[18]
Scheme 1. Synthesis of bifunctional dendron 3-G1.
Figure 2. Second generation bifunctional dendron 3-G2.
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Such reaction leads to AB5 derivatives, in which one func- despite the presence of several phosphoric esters (N=P-OAr
tion is different from the other five functions, used later on and S=P-OAr) and of the Boc protected amines, only the
for the growing of the dendrimeric branches. Some of us carboxylic ester is cleaved under these harsh conditions.
have previously applied this methodology to obtain “Janus” The final step is addition of the benzyl alcohol to isocyan-
dendrimers,[19,20] or for obtaining analogues[21] of a biolo- ate OCN-(CH2)3-Si(OEt)3 in the presence of a stannyl cata-
gically active dendrimer.[22] Here, we first reacted one equiv- lyst[24] to afford dendrimer 7-G1 (Scheme 2). This com-
1
alent of methyl 4-hydroxybenzoate with N3P3Cl6 under ba- pound is mainly characterized by H NMR spectroscopy,
sic conditions, to afford AB5 compound 4-G0, which was which displays a shift in the signal corresponding to the
characterized by 31P NMR spectroscopy, with the presence CH2 group of the core from δ = 4.52 ppm for the alcohol
of one doublet at δ = 26 ppm and one apparent triplet at δ derivative 6-G1 to δ = 5.32 ppm for 7-G1. Dendrimer 7-G1,
2
= 15.4 ppm having a coupling constant JPP = 62 Hz.[23] possessing one triethoxysilyl group and 10 protected
Single crystals suitable for X-ray diffraction were grown amines, is the second type of bifunctional dendrimeric mo-
from ether. The structure of compound 4-G0 is shown in lecule potentially suitable for grafting to silica.
Figure 3.
The unsymmetrical nature of the cyclotriphosphazene
core in compounds 4-G1–7-G1 induces some particular
features in the 31P NMR spectrum. Five of the substituents
bear a phosphorus atom. These five P atoms (noted P1)
are chemically equivalent, but depending on the nature of
substituents R1 and R2, the interactions they undergo
through space (particularly with the sixth substituent of the
core) might be non-equivalent, inducing several signals in
the 31P NMR spectra (Figure 4).
When substituent R1 is a methoxy ester and R2 is Cl
(dendrimer 4-G1), two signals are observed in a 2:3 ratio
for P1 (from left to right in Figure 4). Two signals are also
observed but in a 3:2 ratio when R2 is Boc-protected tyra-
mine, and R1 is either methoxy ester (5-G1) or a triethoxy-
silyl group (7-G1). The largest differences are observed with
Figure 3. X-ray diffraction structure of compound 4-G0.
The next step is growth of the dendrimeric branches by the benzyl alcohol derivative linked to the core (dendrimer
using our classical method,[8] first by reaction with 4- 6-G1). In that case, three signals are observed in a 2:2:1
hydroxybenzaldehyde under basic conditions to afford com- ratio. These 31P NMR spectroscopic data, and especially
pound 4-GЈ0, then by condensation of the aldehydes with the 2:3 or 3:2 ratios, strongly suggest that in solution three
phosphorhydrazide H2NNMe-P(S)Cl2, affording dendrimer arms are oriented above the triphosphazene ring, and two
4-G1 (Scheme 2). Functionalization of the terminal groups below, with one arm up and one arm down on each phos-
is achieved with Boc-protected tyramine (as previously phorus atom of the triphosphazene ring. To confirm this
shown for 2-Gn), affording dendrimer 5-G1. To graft the assumption, we tried to crystallize these dendrimers, but
triethoxysilyl group at the core, the ester of the core of 5-G1 without success. However, we succeeded in obtaining single
has to be deprotected, to afford a benzyl alcohol function. crystals of an analogue of dendrimer 4-G1 bearing six P(S)-
Deprotection/reduction is carried out with LiAlH4, which Cl2 terminal groups instead of five. This analogue is first-
affords alcohol-cored dendrimer 6-G1. 1H NMR spec- generation dendrimer 8-G1,[25] which has been recrystallized
troscopy displays the disappearance of the signal corre- from ethyl ether to afford single crystals. The X-ray diffrac-
sponding to the MeCO2 group. It is important to note that tion structure of dendrimer 8-G1 demonstrates that each
Scheme 2. Synthesis of non-symmetrical bifunctional dendrimer 7-G1.
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Synthesis of Bifunctional Dendrimeric Structures
Figure 4. 31P NMR spectra of phosphorus atoms of the first-generation dendrimer, depending on the nature of the R1 and R2 groups
(signals for N3P3 not shown).
phosphorus atom of the triphosphazene ring has one sub- powders. Furthermore, the presence of disordered solvent
stituent above the ring and one below (Figure 5). It is worth molecules is frequently observed, decreasing the quality of
noting that this is one of the largest dendrimeric structures the data (as observed for 8-G1).
characterized by X-ray diffraction to date (the distance be-
The X-ray data for dendrimer 8-G1 in the solid state con-
tween S2 and S2i is ≈ 23 Å). Indeed, dendrimers are gen- firms the assumptions deduced from the 31P NMR spectro-
erally impossible to crystallize because they are amorphous scopic data in solution for unsymmetrical dendrimers 4-G1–
7-G1. Thus, NMR spectroscopy,[26] and more precisely 31P
NMR spectroscopy [27] is a very precious and highly reliable
tool for the characterization of sophisticated dendritic
structures.[28] On the contrary, mass spectrometry (electro-
spray and MALDI-TOF) is unsuitable to evaluate the pu-
rity of these compounds, owing to important cleavages and
rearrangements during analysis at the level of the hydrazone
linkages.[29]
The last type of dendritic molecule that possesses two
different functions is type C (Figure 1, multi-bifunctional
type C). It differs from both previous types of compounds
described in this paper by two main characteristics: (i) it
possesses several triethoxysilyl groups instead of one, and
(ii) these groups are not located at the core but over the
surface of the dendrimer. The starting material is first-gen-
eration dendrimer 8-G1. The ability to react cleanly only
one Cl of each P(S)Cl2 group when using primary amines
has already been reported.[13,30] This specific reaction works
easily and cleanly with amines, and less cleanly with phen-
ols. Thus the Boc-protected tyramine used for the previous
dendrimeric structures was discarded. We choose Boc-mon-
oprotected ethylene diamine as the amino part, and 3-(tri-
ethoxysilyl)propylamine as the silyl part. Each of these
compounds were tested as the first reagent, and the comple-
mentary one as the second reagent to afford the same final
dendrimer 11-G1 (Scheme 3, Ways a and b). Following Way
a, the first step is reaction with 3-triethoxysilylpropylamine
affording dendrimer 9-G1. Characterization of this com-
pound by 31P NMR spectroscopy displays a single signal
Figure 5. X-ray diffraction structure of first-generation dendrimer
8-G1.
for the terminal groups at δ = 72.8 ppm. Following Way b,
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Scheme 3. Synthesis of symmetrical bifunctional dendrimers 11-G1 and 12-G1.
the first step is reaction with Boc-monoprotected ethylene spite the presence of a large number of free ammoniums,
diamine affording dendrimer 10-G1, characterized in 31P this compound is sufficiently soluble to be fully charac-
NMR spectroscopy by a singlet at δ = 73.8 ppm for the terized, including by 13C NMR spectroscopy, which dis-
1
terminal groups. Dendrimer 11-G1 is obtained in the second plays, as with H NMR spectroscopy, the total disappear-
step, either by reaction of 9-G1 with Boc-monoprotected ance of the signals corresponding to Boc protection.
ethylene diamine (Way a) or by reaction of 10-G1 with 3-
triethoxysilylpropylamine (Way b; Scheme 3). Dendrimer
11-G1 is characterized in particular by 31P NMR spec-
troscopy, which displays a single signal for the terminal
groups at δ = 68.3 ppm. Compound 11-G1 possesses six tri-
ethoxysilyl groups and six protected amines; it is the third
type of dendritic compound potentially suitable to graft to
silica.
For the final aim of our work, trapping of CO2, it is
necessary to have free amines. We tested the possibility of
grafting directly an amine in the last synthetic step, by using
a diamine such as 1,3-diaminopropane. This diamine can-
not be used directly with dendrimer 8-G1, because it gives
Scheme 4. Synthesis of fully Boc-protected dendrimer 13-G1 and
a diazaphosphorinane (six-membered ring)[31] by reaction
its deprotection.
with both Cl atoms of P(S)Cl2. However, 1,3 diamino-
propane reacts cleanly with compound 9-G1, affording den-
drimer 12-G1 (Scheme 3). The completion of the reaction is
monitored by 31P NMR spectroscopy by the disappearance
of the singlet at δ = 72.8 ppm for 9-G1 and the appearance
of a singlet at δ = 67.9 ppm for 12-G1. However, when evap-
Conclusions
orated to dryness, this compound becomes poorly soluble,
We have synthesized three new families of bifunctional
presumably owing to hydrogen bonding or to hydrolysis of dendritic objects, with potential to be used for the elabora-
the SiOEt functions, and no 13C NMR spectrum could be tion of materials suitable for trapping CO2. We have also
recorded.
determined the scope and limits of the deprotection process
In another attempt to have NH2 functions together with to afford free amines linked to the dendritic structures. This
the triethoxysilyl group, we tried to deprotect dendron 3-G1 process elaborated in the homogeneous state (in solution) is
by using trifluoroacetic acid (TFA) in CH2Cl2. After evapo- efficient and specific (no cleavage of the dendritic structure
ration of the solvent, the resulting product was insoluble, observed), and should be usable in the heterogeneous state,
even after adding a solution of triethylamine in tetra- when the dendrimeric molecules will be linked to the solid.
hydrofuran (THF), in an attempt to obtain the neutral com- We intend to use the compounds described in this paper for
pound. To know if the problems of solubility were due to trapping CO2, but the potential of bifunctional dendrimers
the simultaneous presence of free amines and triethoxysilyl is great. Indeed, the synthetic strategies presented here for
groups, we synthesized a dendrimer with Boc-protected obtaining bifunctional dendrimeric compounds are not lim-
tyramine, but without any triethoxysilyl groups. Thus, Boc- ited to this particular case, but could be used for many dif-
protected tyramine was treated with first-generation den- ferent couples of functions. Besides materials, bifunctional
drimer 8-G1, to afford easily dendrimer 13-G1 (Scheme 4). dendrimeric compounds may have potential in the fields of
Deprotection was carried out with TFA, which afforded catalysis (two catalytic entities) or biology (two different
dendrimer 14-G1 with 12 primary ammonium groups. De- drugs or one drug and one targeting function).
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Synthesis of Bifunctional Dendrimeric Structures
CH2N, NCH3), 4.66 (br. s, 8 H, NH), 6.0–7.1 (m, 3 H, H2C=CH),
7.1–7.8 (m, 72 H, CH arom, CH=N) ppm.
Experimental Section
General: All reactions were carried out in the absence of air by
using standard Schlenk techniques and vacuum-line manipulations
when carried out in organic solvents. Commercial samples were
used as received. All solvents were dried and distilled according
to routine procedures before use. Preparative chromatography was
performed with Merck Kieselgel. 1H, 13C, and 31P NMR spec-
troscopy, and HMQC and HMBC measurements were performed
with a Bruker AC200, AM250, AV300 and AMX400. Chemical
shifts are reported relative to TMS for 1H and 13C NMR spec-
troscopy. Chemical shifts for 31P NMR spectra are calculated rela-
tive to phosphoric acid as an external reference (Bruker AM250
operating at 101.2 MHz) or with phosphoric acid as an internal
reference (Bruker AV300 operating at 121.5 MHz). The first-order
peak patterns are indicated as s (singlet), d (doublet), t (triplet), q
(quadruplet), and qn (quintuplet). Complex non-first-order signals
are indicated as m (multiplet). 13C NMR signals were assigned by
using HMQC and HMBC sequences when required. The following
compounds have been prepared according to published procedures:
compounds 1-G1 and 1-G2,[16] 4-G0,[23] 8-G1.[25]
Dendron 3-G1: To a solution of dendron 2-G1 (0.500 g, 0.35 mmol)
dissolved in THF (10 mL) at room temperature was added drop-
wise by syringe a large excess of 3-triethoxysilylpropylamine
(4.1 mL, 17.5 mmol). After stirring overnight, the solvent was evap-
orated under reduced pressure. The light yellow oil obtained was
washed with THF/pentane (1:8; ϫ3). Dendron 3-G1 was isolated
as a pale beige powder in 87% yield (0.502 g, 0.30 mmol). 31P{1H}
2
NMR (101 MHz, CDCl3): δ = 17.5 (d, JPP = 33.9 Hz, PЈ0), 52.3
2
(d, JPP = 33.9 Hz, P0), 62.5 (s, P1) ppm. 1H NMR (300 MHz,
3
CDCl3): δ = 0.53–0.58 (m, 2 H, CH2Si), 1.18 (t, JHH = 6.9 Hz, 9
H, CH3CH2O), 1.44 (s, 36 H, C(CH3)3), 1.46–1.51 (m, 2 H,
3
CH2CH2Si), 2.50 (t, JHH = 6.9 Hz, 2 H, CH2CH2CH2Si), 2.76 (t,
3JHH = 6.9 Hz, 8 H, CH2Ar), 2.92 (m, 4 H, CH2CH2PЈ0), 3.32 (m,
3
3
8 H, CH2N), 3.34 (d, JHP = 10.5 Hz, 6 H, NCH3), 3.8 (q, JHH
=
6.9 Hz, 6 H, CH3CH2O), 4.6 (br. s, 5 H, NH), 7.1–7.3 (m, 20 H,
CH arom), 7.42–7.48 (m, 4 H, CH arom), 7.50–7.53 (m, 2 H, CH
arom), 7.6–7.7 (m, 10 H, CH arom, CH=N) ppm. 13C{1H} NMR
(75 MHz, CDCl3): δ = 7.9 (s, CH2Si), 18.3 (s, CH3CH2O), 23.3 (s,
1
CH2CH2Si), 28.0 (d, JCP = 64 Hz, CH2PЈ0), 28.4 (s, C(CH3)3),
CCDC-929488 (for 4-G0), and -929489 (for 8-G1) 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.
2
32.9 (d, JCP = 13 Hz, P1-N-CH3), 35.6 (s, CH2Ar), 41.7 (s,
CH2NCO), 42.5 (s, CH2CH2PЈ0), 52.3 (s, CH2CH2CH2Si), 58.3 (s,
3
2
CH3CH2O), 79.3 (s, C(CH3)3), 121.5 (d, JCP = 4.6 Hz, C1 ), 121.9
2
3
1
3
(d, 3JCP = 5.1 Hz, C0 ), 127.9 (s, C0 ), 128.3 (dd, JCP = 99.7, JCP
= 5.7 Hz, i-C6H5), 128.8 (d, JCP = 12.7 Hz, m-C6H5), 129.8 (s,
3
Dendron 2-G1: To a solution of dendron 1-G1 (1.00 g, 1.17 mmol) in
dry THF (5 mL) were successively added cesium carbonate (3.36 g,
10.3 mmol) and a solution of Boc protected tyramine (1.22 g,
5.16 mmol) dissolved in THF (5 mL). The progress of the reaction
was monitored by 31P NMR spectroscopy. After 44 h of stirring at
room temperature, the suspension was centrifuged. The colorless
solution was then evaporated to dryness and washed (ϫ3) with
THF/pentane (1:6). Dendron 2-G1 was isolated as a pale beige
powder in 92% yield (1.54 g, 1.08 mmol). 31P{1H} NMR
3
4
2
C1 ), 131.0 (s, C0 ), 131.3 (d, JCP = 10.4 Hz, o-C6H5), 132.5 (d,
4
3
4JCP = 2.7 Hz, p-C6H5), 136.1 (s, C1 ), 139.0 (d, JCP = 13.6 Hz,
CH=N), 149.2 (d, 2JCP = 7.1 Hz, C1 ), 153.0 (d, 2JCP = 9 Hz, C0 ),
1
1
155.8 (s, C=O) ppm.
Dendron 3-G2: To a solution of dendron 2-G2 (3.37 g, 0.977 mmol)
in THF (25 mL) was added aminopropyltriethoxysilane (12.6 mL,
54.3 mmol) at room temperature. The solution was stirred over-
night, then evaporated to dryness, and washed (ϫ3) with THF/
pentane (1:10). Dendron 3-G2 was isolated as a white powder in
84% yield (3.00 g, 0.817 mmol). 31P{1H} NMR (121 MHz,
2
2
(101 MHz, CDCl3): δ = 11.3 (d, JPP = 30.3 Hz, PЈ0), 52.6 (d, JPP
1
= 30.3 Hz, P0), 62.8 (s, P1) ppm. H NMR (300 MHz, CDCl3): δ =
1.43 (s, 36 H, C(CH3)3), 2.75 (t, 3JHH = 6.9 Hz, 8 H, CH2Ar), 3.31
2
2
2
CDCl3): δ = 17.7 (d, JPP = 33.8 Hz, PЈ0), 52.3 (d, JPP = 33.8 Hz,
(m, 8 H, CH2N), 3.33 (d, JHP = 10.5 Hz, 6 H, NCH3), 4.63 (br.,
1
3
3
2
P0), 62.7 (s, P1), 62.8 (s, P2) ppm. H NMR (300 MHz, CDCl3): δ
= 0.53–0.58 (m, 2 H, CH2Si), 1.17 (t, JHH = 7.0 Hz, 9 H,
s, 4 H, NH), 6.1 (ddd, JHP = 24.0, JHHa = 18.3, JHH = 1.0 Hz,
3
1 H, Hc), 6.3 (ddd, 3JHP = 45.9, 3JHHa = 12.3, JHH = 1.0 Hz, 1 H,
2
2
3
3
4
CH3CH2O), 1.41 (s, 72 H, C(CH3)3), 1.50 (m, 2 H, CH2CH2Si),
Hb), 6.7 (dddd, JHP = 25.4, JHHc = 18.3, JHHb = 12.3, JHP
=
3
2.47 (t, JHH = 7.0 Hz, 2 H, CH2CH2CH2Si), 2.73 (br. t, 16 H,
1.0 Hz, 1 H, Ha), 7.11–7.28 (m, 20 H, CH arom), 7.42–7.48 (m, 4
H, CH arom), 7.52–7.55 (m, 2 H, CH arom), 7.62–7.69 (m, 10 H,
CH arom, CH=N) ppm. 13C{1H} NMR (75.5 MHz, CDCl3): δ =
CH2Ar), 2.87 (m, 4 H, CH2CH2PЈ0), 3.3–3.5 (m, 34 H, CH2N,
3
NCH3), 3.75 (q, JHH = 7.0 Hz, 6 H, CH3CH2O), 4.6 (br., s, 9 H,
NH), 6.7–7.8 (m, 72 H, CH arom, CH=N) ppm. 13C{1H} NMR
2
28.4 (s, C(CH3)3), 33.0 (d, JCP = 13 Hz, P1-N-CH3), 35.6 (s,
CH2Ar), 41.7 (s, CH2N), 79.2 (s, C(CH3)3), 121.5 (d, 3JCP = 4.6 Hz,
(75 MHz, CDCl3): δ = 6.5 (s, CH2Si), 17.3 (s, CH3CH2O), 22.2 (s,
2
2
2
4
C1 ), 121.9 (d, 3JCP = 5.1 Hz, C0 ), 127.04 (s, C1 ), 127.07 (dd, 1JCP
CH2CH2Si), 27.4 (s, C(CH3)3), 32.0 (br. d, JCP = 13 Hz, P-N-
3
3
3
CH3), 34.6 (s, CH2Ar), 40.8 (br. s, CH2NCO), 41.5 (s, CH2CH2PЈ0),
51.3 (s, CH2CH2CH2Si), 57.3 (s, CH3CH2O), 79.0 (s, C(CH3)3),
= 97.6, JCP = 4.6 Hz, i-C6H5), 127.9 (s, C0 ), 128.7 (d, JCP
=
=
3
4
2
13 Hz, m-C6H5), 129.8 (s, C1 ), 131.0 (s, C0 ), 132.1 (d, JCP
120.4 (d, 3JCP = 5 Hz, C2 ), 121.0 (d, JCP = 5 Hz, C0 , C1 ), 127.2
2
3
2
2
4
4
10.9 Hz, o-C6H5), 132.7 (d, JCP = 2.8 Hz, p-C6H5), 136.1 (s, C1 ),
3
1
3
3
2
(s, C0 ), 128.0 (d, JCP = 110 Hz, i-C6H5), 127.7 (d, JCP = 12 Hz,
136.8 (s, CH2=), 139.0 (d, JCP = 13.6 Hz, CH=N), 149.2 (d, JCP
3
3
4
2
1
2
1
m-C6H5), 128.8 (s, C1 , C2 ), 130.1 (s, C0 ), 130.5 (d, JCP = 10 Hz,
= 7.2 Hz, C1 ), 153.0 (d, JCP = 9 Hz, C0 ), 155.9 (s, C=O) ppm.
4
4
4
o-C6H5), 131.5 (d, JCP = 3 Hz, p-C6H5), 131.1 (s, C1 , C2 ), 138.0
(br. d, CH=N), 148.1 (s, C2 ), 151.7 (s, C1 ), 152.4 (s, C0 ), 154.8
(s, C=O) ppm.
Dendron 2-G2: To a solution of dendron 1-G2 (2.00 g, 1.086 mmol)
in dry THF (50 mL) were successively added cesium carbonate
(3.11 g, 9.55 mmol) and a solution of Boc protected tyramine
1
1
1
(2.27 g, 9.55 mmol). After 18 h of stirring at room temperature, the Dendrimer 4-GЈ0: Cesium carbonate (5.40 g, 16.5 mmol) and 4-
suspension was centrifuged. The colorless solution was then evapo-
rated to dryness and washed (ϫ3) with THF/pentane (1:10). Den-
dron 2-G2 was isolated as a white powder in 90% yield (3.37 g,
hydroxybenzaldehyde (1.01 g, 8.25 mmol) were added successively
to a solution of compound 4-G0 (0.70 g, 1.51 mmol) in THF
(100 mL). The reaction mixture was stirred vigorously overnight
before being centrifuged. The supernatant was collected and the
2
0.977 mmol). 31P{1H} NMR (121 MHz, CDCl3): δ = 11.0 (d, JPP
2
= 30.2 Hz, PЈ0), 52.7 (d, JPP = 30.2 Hz, P0), 62.2 (s, P1), 62.5 (s, solvent evaporated under reduced pressure. The resulting residue
P2) ppm. 1H NMR (300 MHz, CDCl3): δ = 1.51 (s, 72 H,
was purified by flash chromatography (AcOEt/hexane, 1:1) to give
desired product 4-GЈ0, which was isolated as a white powder in
3
C(CH3)3), 2.81 (t, JHH = 6 Hz, 16 H, CH2Ar), 3.3–3.5 (m, 34 H,
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
7

Job/Unit: O30456
/KAP1
Date: 09-07-13 16:51:25
Pages: 10
A.-M. Caminade et al.
G1 isolated as a white powder in 99% yield (0.40 g, 0.11 mmol).
FULL PAPER
82% yield (1.10 g, 1.24 mmol). 31P{1H} NMR (101 MHz, CDCl3):
1
δ = 7.2 (m, P0) ppm. H NMR (200 MHz, CDCl3): δ = 3.92 (s, 3 31P{1H} NMR (202 MHz, CDCl3): δ = 8.7 (s, P0), 62.9 (s, P1), 63.0
H, CH3), 7.01 (d, JHH = 8.6 Hz, 2 H, CЈ0 H), 7.13 (m, 10 H, CH (s, P1), 63.1 (s, P1), ppm. 1H NMR (500 MHz, CDCl3): δ = 1.42 (s,
3
2
3
3
arom), 7.36 (m, 10 H, CH arom), 7.82 (d, JHH = 8.6 Hz, 2 H,
90 H, C(CH3)3), 2.72 (m, 20 H, CH2Ar), 3.24 (d, JHP = 10 Hz, 3
3
3
CЈ0 H) ppm. 13C{1H} NMR (75 MHz, CDCl3): δ = 52.4 (s, OCH3), H, P1-NCH3), 3.26–3.31 (m, 20 H, CH2N), 3.29 (d, JHP = 10 Hz,
2
2
3
3
120.5 (s, CЈ0 ), 121.2 (s, C0 ), 127.6 (s, CЈ0 ), 131.4 (s, C0 ), 131.9 12 H, P1-NCH3), 4.52 (m, 2 H, CH2OH), 4.62–4.77 (br. s, 10 H,
4
4
1
1
(s, CЈ0 ), 133.7 (s, C0 ), 153.4 (s, CЈ0 ), 154.5 (s, C0 ), 165.9 (s,
C=O), 190.5 (s, CHO) ppm. MS (DCI/NH3): m/z = 892 [M +
H]+.
NH), 6.9–7.2 (m, 54 H, CH arom), 7.60–7.66 (m, 15 H, CH arom,
CH=N) ppm. 13C{1H} NMR (125 MHz, CDCl3): δ = 28.4 (s,
2
C(CH3)3), 33.0 (d, JCP = 11.3 Hz, P1-N-CH3), 35.5 (s, CH2Ar),
2
41.7 (s, CH2N), 63.9 (s, CH2OH), 79.3 (s, C(CH3)3), 120.9 (s, CЈ0 ),
Dendrimer 4-G1: Compound 4-GЈ0 (3.568 g, 4.00 mmol) was dis-
solved in THF and the solution was cooled to 0 °C with an ice
bath. To this solution was added H2NNMeP(S)Cl2 (excess of
0.2 equiv. per aldehyde function). The progress of the reaction was
monitored by 31P NMR spectroscopy. After stirring overnight, the
solution was transferred by cannula in dry pentane (6ϫ the volume
of the previous solution). The suspension was filtered by cannula.
The powder obtained was taken up in THF and washed (ϫ2) with
pentane. The powder was dried under vacuum for 2 h at 40 °C.
Dendrimer 4-G1 was isolated as a white powder in 98% yield
2
2
3
3
4
121.4 (C0 , C1 ), 128.0 (s, C0 ), 129.9 (s, C1 ), 132.0 (s, C0 ), 132.2
4
4
1
(s, C0 ), 136.3 (s, C1 ), 138.4 (br. s, CH=N), 149.1 (s, C1 ), 151.2
(d, JCP = 10 Hz, C0 ), 155.9 (s, C=O) ppm.
2
1
Dendrimer 7-G1: Isocyanate propyltriethoxysilane (NCO-PTEOS)
(0.05 mL, 0.19 mmol) and di-n-butyltindilaurate (10 μL, catalyst)
were successively added to a solution of compound 6-G1 (88 mg,
0.024 mmol) dissolved in THF (3 mL). The mixture was then
heated to reflux for 48 h and the solvent was evaporated in vacuo.
The resulting product was washed with THF/pentane (1:8) until the
(6.65 g, 3.92 mmol). 31P{1H} NMR (101 MHz, CDCl3): δ = 8.1 (m, excess NCO-PTEOS was eliminated (3 to 4 washes). Compound 7-
P0), 62.4 (s, P1 major), 62.7 (s, P1 minor) ppm. 1H NMR (250 MHz,
G1 was isolated as a white powder in 97% yield (91 mg,
3
3
CDCl3): δ = 3.51 (d, JHP = 14 Hz, 9 H, P1-NCH3), 3.53 (d, JHP
0.023 mmol). 31P{1H} NMR (121 MHz, CDCl3): δ = 8.7 (s, P0),
3
= 14 Hz, 6 H, P1-NCH3), 3.91 (s, 3 H, OCH3), 7.0 (d, JHH
=
62.4 (s, P1), 62.5 (s, P1) ppm. 1H NMR (300 MHz, CDCl3): δ =
2
3
8.4 Hz, 2 H, CЈ0 H), 7.04 (m, 10 H, CH arom), 7.61 (m, 15 H, CH 0.55–0.57 (m, 2 H, CH2Si), 1.21 (t, JHH = 6.9 Hz, 9 H,
3
3
arom, N=CH), 7.84 (d, JHH = 8.4 Hz, 2 H, CЈ0 H) ppm. 13C{1H} CH3CH2O), 1.42 (s, 90 H, C(CH3)3), 1.59 (m, 2 H, CH2CH2Si),
NMR (62.9 MHz, CDCl3): δ = 31.9 (d, 2JCP = 12.5 Hz, P1-NCH3),
2.72 (m, 20 H, CH2Ar), 3.15 (m, 2 H, CH2CH2CH2Si), 3.2–3.4 (m,
2
2
3
32.0 (d, JCP = 12.6 Hz, P1-NCH3), 52.3 (s, OCH3), 120.5 (s, CЈ0 ), 25 H, CH2N, P1-NCH3), 3.79 (q, JHH = 6.9 Hz, 6 H, CH3CH2O),
2
3
3
4
121.4 (s, C0 ), 126.9 (s, CЈ0 ), 128.3 (s, C0 ), 131.5 (s, C0 ), 132.0 (s,
4.65 (br. s, 10 H, NH), 4.93 (br. s, 2 H, CH2O), 6.9–7.2 (m, 54 H,
CЈ0 ), 140.5 (d, JCP = 19.0 Hz, CH=N), 140.6 (d, JCP = 18.9 Hz, CH arom), 7.55–7.70 (m, 15 H, CH arom, CH=N) ppm. 13C{1H}
4
3
3
2
1
2
CH=N), 151.6 (d, JCP = 8.7 Hz, C0 ), 153.8 (d, JCP = 4.0 Hz,
NMR (125 MHz, CDCl3): δ = 7.6 (s, CH2Si), 18.3 (s, CH3CH2O),
1
2
CЈ0 ), 166.2 (s, C=O), 190.5 (s, CHO) ppm.
23.3 (s, CH2CH2Si), 28.3 (s, C(CH3)3), 33.0 (d, JCP = 11.3 Hz, P1-
N-CH3), 35.6 (s, CH2Ar), 41.7 (s, CH2N), 43.6 (s, CH2CH2CH2Si),
58.4 (s, CH3CH2O), 65.5 (s, CH2O), 79.2 (s, C(CH3)3), 120.9 (s,
C0 ), 121.33 (s, C0 ), 121.39 (s, C1 ), 128.2 (s, C0 ), 129.3 (s, C0 ),
Dendrimer 5-G1: Cesium carbonate (0.42 g, 1.30 mmol) and Boc
protected tyramine (0.31 g, 1.30 mmol) were successively added to
a solution of compound 4-G1 (0.41 g, 0.24 mmol) in THF (15 mL).
The progress of the reaction was monitored by 31P NMR spec-
troscopy. After 48 h of stirring at room temperature, the suspension
was centrifuged. The colorless solution was removed and the sol-
vent evaporated under reduced pressure. The resulting residue was
purified by flash chromatography (dioxane/CH2Cl2, 1:1) to give de-
sired product 5-G1 isolated as a white powder in 94% yield (0.83 g,
2
2
2
3
3
3
4
4
4
129.9 (s, C1 ), 132.15 (s, C0 ), 132.21 (s, C0 ), 133.9 (s, C0 ), 136.3
4
1
(s, C1 ), 138.59 (br. s, CH=N), 138.63 (br. s, CH=N), 149.1 (s, C1 ),
1
1
1
150.0 (s, C0 ), 151.21 (s, C0 ), 151.24 (s, C0 ), 155.9 (s, C=O Boc),
156.2 (s, C=O) ppm.
Dendrimer
9-G1:
3-Triethoxysilylpropylamine
(0.31 mL,
1.31 mmol) dissolved in THF (20 mL) and triethylamine (0.18 mL,
0.23 mmol). 31P{1H} NMR (121 MHz, CDCl3): δ = 8.6 (m, P0), 1.31 mmol) were slowly added dropwise over 30 min to a solution
62.5 (s, P1), 62.6 (s, P1) ppm. 1H NMR (250 MHz, CDCl3): δ = of dendrimer 8-G1 (0.400 g, 0.22 mmol) in THF (30 mL) at 0 °C.
3
1.40 (s, 90 H, C(CH3)3), 2.69 (br. t, JHH = 6.9 Hz, 20 H, CH2Ar), After stirring for 1 h at 0 °C, the mixture was filtered by cannula
3.22 (m, 35 H, CH2N, P1-NCH3), 3.79 (s, 3 H, OCH3), 4.63 (br. s,
and the solvent was evaporated under reduced pressure to yield a
10 H, NH), 6.9–7.2 (m, 52 H, CH arom), 7.5–7.7 (m, 15 H, CH powder that was then washed (ϫ2) with THF/pentane (1:8). Prod-
3
3
arom, CH=N), 7.83 (d, JHH = 8.7 Hz, 2 H, CЈ0 H) ppm. 13C{1H} uct 9-G1 was obtained as a white powder in 98% yield (0.63 g,
2
NMR (62.9 MHz, CDCl3): δ = 28.4 (s, C(CH3)3), 33.0 (d, JCP
=
0.21 mmol). 31P{1H} NMR (101 MHz, C6D6): δ = 8.4 (s, P0), 73.5
11.8 Hz, P1-N-CH3), 35.6 (s, CH2Ar), 41.7 (s, CH2N), 52.2 (s, (s, P1) ppm. 1H NMR (300 MHz, C6D6): δ = 0.76 (t, 3JHH = 7.9 Hz,
2
2
3
OCH3), 79.2 (s, C(CH3)3), 120.7 (s, CЈ0 ), 121.31 (C0 ), 121.37 12 H, CH2Si), 1.24 (t, JHH = 7.2 Hz, 54 H, CH3CH2O), 1.82 (m,
(C1 ), 126.9 (s, CЈ0 ), 128.3 (s, C1 ), 129.8 (s, C1 ), 131.2 (s, C0 ),
132.3 (s, CЈ0 ), 136.2 (s, C1 ), 138.5 (d, JCP = 18.7 Hz, CH=N),
149.1 (d, JCP = 5.9 Hz, C1 ), 151.1 (s, C0 ), 153.6 (s, CЈ0 ), 155.8 CH3CH2O), 4.8 (br. s, 6 H, NH), 7.2–7.6 (m, 30 H, CH arom,
12 H, CH2CH2Si), 3.10 (d, 3JHP = 13.2 Hz, 18 H, P1-NCH3), 3.35–
3.46 (m, 12 H, CH2CH2CH2Si), 3.87 (q, JHH = 7.2 Hz, 36 H,
2
3
3
3
4
4
4
3
3
2
1
1
1
(s, NC=O), 166.1 (s, OC=O) ppm.
CH=N) ppm. 13C{1H} NMR (75 MHz, C6D6): δ = 7.7 (s, CH2Si),
4
18.4 (s, CH3CH2O), 24.6 (d, JCP = 8.1 Hz, CH2CH2Si), 30.8 (d,
Dendrimer 6-G1: Compound 5-G1 (0.41 g, 0.11 mmol) dissolved in
ether (3 mL) was added dropwise by syringe over 2 min to a suspen-
sion of LiAlH4 in ether (5 mL) (13.0 mg, 0.32 mmol) at 0 °C. The
reaction was monitored by TLC and after 3 h of stirring the reac-
tion mixture was hydrolyzed with water (5 mL) and extracted with
dichloromethane (3ϫ 10 mL). The organic phases were combined,
dried with sodium sulfate, filtered and evaporated under reduced
pressure. The white residue obtained was purified by flash
chromatography (AcOEt/hexane, 15:5) to yield desired product 6-
2JCP = 10.6 Hz, P1-N-CH3), 44.7 (s, CH2CH2CH2Si), 58.4 (s,
2
3
4
CH3CH2O), 121.4 (s, C0 ), 128.3 (s, C0 ), 132.4 (s, C0 ), 138.6 (d,
3JCP = 15.6 Hz, CH=N), 151.6 (d, JCP = 2.5 Hz, C0 ) ppm.
2
1
Dendrimer 10-G1: Monoprotected ethylenediamine (0.420 g,
2.62 mmol) dissolved in THF (10 mL) and triethylamine
(0.364 mL, 2.62 mmol) were added at room temperature success-
ively over 10 min to a solution of dendrimer 8-G1 (0.800 g,
0.438 mmol) in THF (50 mL). The mixture was stirred for 3 h, fil-
8
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Eur. J. Org. Chem. 0000, 0–0

Job/Unit: O30456
/KAP1
Date: 09-07-13 16:51:25
Pages: 10
Synthesis of Bifunctional Dendrimeric Structures
tered by cannula and the solvent was evaporated under reduced
pressure. The resulting powder was then washed (ϫ2) with THF/
pentane (1:8). Dendrimer 11-G1 was isolated as a white powder in
a solution of dendrimer 8-G1 (1.00 g, 0.547 mmol) in THF (10 mL).
The progress of the reaction was monitored by 31P NMR spec-
troscopy. After stirring for 20 h at room temperature, the suspen-
98% yield (1.097 g, 0.429 mmol). 31P{1H} NMR (101 MHz, sion was centrifuged. The resulting colorless solution was then
CDCl3): δ = 8.4 (s, P0), 73.8 (s, P1) ppm. 1H NMR (250 MHz, washed (ϫ3) with THF/pentane (1:5). The product 13-G1 was iso-
CDCl3):
CH2CH2NHBoc), 3.32 (d, JHP = 13.3 Hz, 18 H, P1-NCH3), 3.36 NMR (121 MHz, CDCl3): δ = 8.5 (s, P0), 62.8 (s, P1) ppm. 1H
(m, 12 H, CH2NHBoc), 5.05 (br. s, 6 H, NH), 5.20 (br. s, 6 H, NMR (300 MHz, CDCl3): δ = 1.41 (s, 108 H, C(CH3)3), 2.69 (t,
δ
=
1.42 (s, 54 H, C(CH3)3), 3.12 (m, 12 H,
lated as a white powder in 94% yield (2.10 g, 0.514 mmol). 31P{1H}
3
NH), 7.02 (m, 12 H, CH arom), 7.58 (m, 12 H, CH arom), 7.59 (s, 3JHH = 6.9 Hz, 24 H, CH2Ar), 3.22 (d, JHP = 10.2 Hz, 18 H, P1-
3
6 H, CH=N) ppm. 13C{1H} NMR (63 MHz, CDCl3): δ = 28.4 (s,
NCH3), 3.26–3.31 (m, 24 H, CH2N), 4.69 (br. s, 12 H, NH), 6.97–
2
C(CH3)3), 31.2 (d, JCP
= 10.4 Hz, P1-N-CH3), 41.5 (s, 7.12 (m, 48 H, CH arom), 7.61–7.64 (m, 18 H, CH arom,
CH2CH2NHBoc), 43.0 (s, CH2CH2NHBoc), 79.3 (s, C(CH3)3), CH=N) ppm. 13C{1H} NMR (75 MHz, CDCl3): δ = 28.4 (s,
121.3 (s, C0 ), 128.4 (s, C0 ), 131.6 (s, C0 ), 139.4 (d, JCP = 13 Hz, C(CH3)3), 32.9 (d, JCP = 11.9 Hz, P1-N-CH3), 35.6 (s, CH2Ar),
CH=N), 151.2 (s, C0 ), 156.4 (s, C=O) ppm.
2
3
4
3
2
1
2
2
41.7 (s, CH2N), 79.2 (s, C(CH3)3), 121.33 (s, C0 ), 121.39 (s, C1 ),
3
3
4
4
128.2 (s, C0 ), 129.8 (s, C1 ), 132.2 (s, C0 ), 136.3 (s, C1 ), 138.5 (d,
Dendrimer 11-G1. Way a: Monoprotected ethylenediamine (0.210 g,
1.31 mmol) dissolved in THF (20 mL) and triethylamine (0.18 mL,
1.31 mmol) were added at room temperature successively over
10 min to a solution of compound 9-G1 (0.646 g, 0.220 mmol) in
THF (40 mL). After stirring overnight at room temperature, the
mixture was filtered by cannula and the solvent was evaporated
under reduced pressure. The resulting powder was then washed
(ϫ2) with THF/pentane (1:8). Dendrimer 11-G1 was isolated as a
white powder in 94% yield (0.76 g, 0.207 mmol).
3JCP = 13.9 Hz, CH=N), 149.0 (d, JCP = 7.1 Hz, C1 ), 151.2 (s,
2
1
1
C0 ), 155.9 (s, C=O) ppm.
Dendrimer 14-G1: Trifluoroacetic acid (3 mL) in dichloromethane
(5% v/v) was added at room temperature to a solution of com-
pound 13-G1 (0.23 g, 0.0562 mmol) in dichloromethane (1 mL). Af-
ter 3 h of stirring, the solvent was evaporated under reduced pres-
sure. The oily residue was taken (ϫ4) in dichloromethane with
evaporation of the solvent. The compound was then checked by
1
31P and H NMR in CD3OD. The deprotection was not complete.
Way b: 3-Triethoxysilylpropylamine (0.62 mL, 2.628 mmol) and tri-
ethylamine (0.364 mL, 2.628 mmol) were added dropwise to a solu-
tion of dendrimer 10-G1 (1.12 g, 0.438 mmol) in THF (30 mL). The
mixture was stirred overnight, filtered by cannula and the solvent
was evaporated under reduced pressure. The resulting powder was
then washed (ϫ2) with THF/pentane (1:8). Dendrimer 11-G1 was
isolated as a white powder in 96% yield (1.55 g, 0.420 mmol).
31P{1H} NMR (121 MHz, CDCl3): δ = 8.1 (s, P0), 68.3 (s, P1) ppm.
1H NMR (300 MHz, CDCl3): δ = 0.63 (m, 12 H, CH2Si), 1.20 (t,
3JHH = 7.2 Hz, 54 H, CH3CH2O), 1.41 (s, 54 H, C(CH3)3), 1.63
(m, 12 H, CH2CH2Si), 2.97 (m, 12 H, CH2CH2CH2Si), 3.12–3.22
The oily residue was redissolved in trifluoroacetic acid (3 mL) in
dichloromethane (5% v/v) for 18 additional hours. The solvent was
evaporated and the product 14-G1 was taken up four times in
dichloromethane with concomitant evaporation of solvent (see
above). Dendrimer 14-G1 was isolated as a white powder in 96%
yield (0.23 g, 0.0532 mmol). 31P{1H} NMR (121 MHz, CD3OD): δ
1
= 7.5 (s, P0), 61.3 (s, P1) ppm. H NMR (300 MHz, CD3OD): δ =
2.87–2.93 (m, 24 H, CH2Ar), 3.09–3.14 (m, 24 H, CH2N), 3.14–
3
3
3.36 (d, JHP = 10.2 Hz, 18 H, P1-NCH3), 6.92 (d, JHH = 8.4 Hz,
3
12 H, CH arom), 7.14–7.23 (m, 48 H), 7.62 (d, JHH = 8.4 Hz,
12 H, CH arom), 7.78 (br. s, 6 H, CH=N) ppm. 13C{1H} NMR
(62.5 MHz, CD3OD): δ = 33.0 (d, 2JCP = 11.8 Hz, P1-N-CH3), 33.2
(s, CH2Ar), 41.1 (s, CH2N), 117.4 (q, 1JCF = 292.1 Hz, CF3COOH),
3
(m, 12 H, CH2CH2NHBoc), 3.15 (d, JHP = 9.3 Hz, 18 H, P1-
NCH3), 3.25 (m, 12 H, CH2NHBoc), 3.35 (br. s, 6 H, NH), 3.79
3
(q, JHH = 7.2 Hz, 36 H, CH3CH2O), 5.1 (br. s, 6 H, NH), 6.9–7.1
2
3
2
3
121.8 (s, C0 ), 122.2 (d, JCP = 3.5 Hz, C1 ), 128.9 (s, C0 ), 130.4
(m, 12 H, CH arom), 7.4–7.6 (m, 18 H, CH arom, CH=N) ppm.
3
4
4
(s, C1 ), 133.3 (s, C0 ), 134.7 (s, C1 ), 139.8 (d, 3JCP = 13 Hz, C=N),
13C{1H} NMR (75 MHz, CDCl3): δ = 7.7 (s, CH2Si), 18.3 (s,
2
1
1
2
150.4 (d, JCP = 15.8 Hz, C1 ), 150.42 (s, C0 ), 162.19 (q, JCF
36.1 Hz, CF3COO) ppm.
=
3
CH3CH2O), 24.8 (d, JCP = 7.2 Hz, CH2CH2Si), 28.4 (s, C(CH3)
2
3), 31.0 (d, JCP = 10.4 Hz, P1-N-CH3), 41.5 (s, CH2CH2NHBoc),
41.7 (s, CH2CH2NHBoc), 44.0 (s, CH2CH2CH2Si), 58.4 (s,
Supporting Information (see footnote on the first page of this arti-
2
3
1
cle): Copies of the 31P, H, and 13C NMR spectra of all new com-
CH3CH2O), 79.2 (s, C(CH3)3), 121.1 (s, C0 ), 127.6 (s, C0 ), 132.5
4
3
1
(s, C0 ), 136.6 (d, JCP = 12.6 Hz, CH=N), 150.7 (s, C0 ), 156.3 (s,
pounds.
C=O) ppm.
Dendrimer 12-G1:
A solution of dendrimer 9-G1 (0.350 g,
Acknowledgments
0.119 mmol) in THF (3 mL) was added dropwise to 1,3 diami-
nopropane (10 mL). The resulting mixture was stirred for 45 min
at room temperature then evaporated under reduced pressure. THF
(10 mL) was added to the residue; the resulting mixture was filtered
through cannula, and the solution was evaporated to dryness, to
afford compound 12-G1 as a white powder in 98% yield (0.37 g,
0.117 mmol). 31P{1H} NMR (101 MHz, CDCl3): δ = 8.2 (s, P0),
The authors thank for financial support by the Institut Français
du Pétrole Energies Nouvelles (IFPEN) (in particular for a grant
to D. R.), the Deutsche Forschungsgemeinschaft (DFG) (grant to
S. F.), the Fundación Ramón Areces (grant to A. P. Q.) and the
Centre National de la Recherche Scientifique (CNRS). Sonia Lad-
eira is thanked for X-ray analyses.
1
67.9 (s, P1) ppm. H NMR (200 MHz, CDCl3): δ = 0.61 (m, 12 H,
3
CH2Si), 1.25 (t, JHH = 6 Hz, 54 H, CH3CH2O), 1.45 (m, 12 H,
3
CH2CH2NH2), 1.63 (m, 12 H, CH2CH2Si), 2.76 (t, JHH = 7 Hz,
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Job/Unit: O30456
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Date: 09-07-13 16:51:25
Pages: 10
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