Study of the structure and photochemical decomposition of azidoadamantanes entrapped in α- And β-cyclodextrin

Article abstract of DOI:10.1002/ejoc.201001525

Photolysis of 1-azidoadamantane (1), either in its neat state or in alkane solution, yields the dimeric product 4. In contrast, amino alcohol 3 is formed as the sole product in high yield when 1 is confined within cyclodextrins (CyDs). To understand the discrepancy in product distribution caused by supramolecular encapsulation, CyD inclusion complexes (ICs) of azidoadamantanes were fully characterized. Indeed, intermolecular selectivity was influenced by reactant orientation and mobility. Both, 1- (1) and 2-azidoadamantane (5) yield 1:1 ICs with β-CyD and 1:2 ICs with α-CyD. As inferred from 2-D ROESY spectra in D₂O, 1 is accommodated at the wider rim of β-CyD with the azido group pointing into the cavity. However, two principal orientations of 5 inside the cavity of β-CyD were found. Single crystal X-ray analysis of solid 5 also demonstrates a bimodal orientation within β-CyD. In addition, the first induced circular dichroism (ICD) study of an alkyl azide entrapped within CyD cavities is reported. From these data, it was concluded that azide 1 is bound more strongly within β-CyD in H ₂O/EtOH = 8:2 at 293 K (K_a = 20240 ± 1000 M ^-1) than is 2-azidoadamantane (5) (K_a = 7450 ± 400 M^-1).

Full text of DOI:10.1002/ejoc.201001525

FULL PAPER
DOI: 10.1002/ejoc.201001525
Study of the Structure and Photochemical Decomposition of
Azidoadamantanes Entrapped in α- and β-Cyclodextrin
[a]
[a]
[a]
[b]
Udo H. Brinker,* Peter Walla, Daniel Krois, and Vladimir B. Arion
Keywords: Supramolecular chemistry / Azides / Imines / Cyclodextrins / Circular dichroism
Photolysis of 1-azidoadamantane (1), either in its neat state
or in alkane solution, yields the dimeric product 4. In con-
trast, amino alcohol 3 is formed as the sole product in high
yield when 1 is confined within cyclodextrins (CyDs). To
understand the discrepancy in product distribution caused by
supramolecular encapsulation, CyD inclusion complexes
wider rim of β-CyD with the azido group pointing into the
cavity. However, two principal orientations of 5 inside the
cavity of β-CyD were found. Single crystal X-ray analysis of
solid 5 also demonstrates a bimodal orientation within β-
CyD. In addition, the first induced circular dichroism (ICD)
study of an alkyl azide entrapped within CyD cavities is re-
ported. From these data, it was concluded that azide 1 is
(ICs) of azidoadamantanes were fully characterized. Indeed,
intermolecular selectivity was influenced by reactant orienta-
tion and mobility. Both, 1- (1) and 2-azidoadamantane (5)
yield 1:1 ICs with β-CyD and 1:2 ICs with α-CyD. As inferred
bound more strongly within β-CyD in H
2
O/EtOH = 8:2 at
–
1
293 K (K
(K = 7450Ϯ400
a
= 20240Ϯ1000 M ) than is 2-azidoadamantane (5)
–
1
a
M ).
2
from 2-D ROESY spectra in D O, 1 is accommodated at the
Introduction
ment of these species by CyDs does indeed change their
reactivity. We also investigated whether photoaffinity label-
ing occurred, by innermolecular reaction between guest and
host, leading to modified CyDs. To further our knowledge
about these supramolecular aggregates, correlations of the
geometry inferred from 2-D ROESY measurements with in-
duced circular dichroism (ICD) spectra are described. Fi-
Azides[1] have served as nitrene[2] precursors for quite
some time. The reactive intermediates are generated after
elimination of molecular nitrogen by either thermal or pho-
tochemical methods. These electron-deficient species can re-
act immediately with surrounding molecules, thus making
them useful photoaffinity labels.[
3,4]
nally, the association constant (K ) values for 1 and 5 with
a
Cyclodextrins (CyDs) are cyclic oligosaccharides made
through the glycosidic 1Ǟ4 linkage of α-d-glucopyranose
monomers. The truncated cone-shaped structures possess a
hydrophobic interior comprising fugacious water molecules
that readily escape when substituted by less polar guest mo-
β-CyDs were determined by ICD.
Results and Discussion
[
5]
Photolysis of 1-azidoadamantane (1) initiates the expul-
lecules. The ability to include organic molecules within
CyDs has long been exploited by commercial industries,
thereby ensuring a bright future for these useful inclusion
sion of N and results in the temporary formation of 4-
2
azatricyclo[4.3.1.13 ]undec-3-ene (2) (Scheme 1). This oc-
curs either in one step or in two steps involving the interme-
diate 1-adamantanylnitrene. Further reaction of unstable
bridgehead imine 2 depends on its surroundings. Addition
by an adventitious water molecule leads to the formation
,8
[
6]
compounds.
It has already been shown that CyDs can dramatically
alter the reaction pathways of carbene intermediates en-
trapped within them.[7] One therefore wonders whether the
of 4-azatricyclo[4.3.1.13 ]undecan-3-ol (3). Under anhy-
,8
[8]
selectivity of the reactions of azidoadamantanes 1 and 5 or
their corresponding nitrene intermediates will be altered as
well. Herein, we demonstrate that supramolecular confine-
drous conditions, dimerization yields 9,18-diaza-
2,6:4,9:12,16,14,18-tetramethanodispiro[7.7.1.1]octadecane
(
4), which features a 1,3-diazetidine core indicative of a
[
9]
head-to-tail cycloaddition. Hence, the photolysis of 1
either in the solid state or in an alkane solution afforded
dimer 4 only (Table 1, entries 1, 2).
[
a] Lehrstuhl für Physikalisch-Organische Chemie und
Strukturchemie, Institut für Organische Chemie, Universität
Wien,
Währinger Straße 38, 1090 Wien, Austria
Fax: +43-1-4277-52140
In stark contrast, however, photolysis of solid 1@β-CyD
E-mail: udo.brinker@univie.ac.at
and 1@(α-CyD)
2
ICs afforded 3 exclusively (Table 1, entries
[
b] Institut für Anorganische Chemie, Universität Wien,
Währinger Straße 42, 1090 Wien, Austria
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201001525.
3, 4). Clearly, using CyDs significantly altered the reaction
pathway of the intermediate generated from 1 inside the
host cavity. A confined, reactive intermediate lacks the time
Eur. J. Org. Chem. 2011, 1249–1255
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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U. H. Brinker, P. Walla, D. Krois, V. B. Arion
FULL PAPER
Scheme 1. Photolyses products of 1.
Table 1. Photolyses products of azidoadamantanes 1 and 5.
Entry
Yield [%][a]
3
4
6
8
1
2
3
4
5
6
7
8
1 (solid state)
–
–
84
88
–
–
–
–
–
–
–
–
15
5
1 (alkane solution)
94[
91
–
b]
1@(α-CyD)
1@β-CyD
2
traces
–
5 (solid state)
–
–
–
–
84
87
81
77
5 (alkane solution)
–
–
–
5@(α-CyD)
5@β-CyD
2
10
23
Scheme 2. Photolyses products of 5.
[
a] Yields were determined by quantitative analytical GC-FID. [b]
conducted with the aziadamantane@α-CyD IC, for which
Traces of 1-adamantanamine and 1-adamantanol were detected by
GC-MS.
a chemospecific insertion of adamantanylidene into the
[
10,12]
CyD’s 3-OH and 2-OH bonds takes place.
Physical methods, such as X-ray diffraction, two-dimen-
and ability to interact with other intermediates or their pre- sional rotating-frame Overhauser effect spectroscopy (2-D
cursors. So, intermediate 2 cannot dimerize to give 4 due to ROESY), and induced circular dichroism (ICD) were em-
its incarceration. This behavior differs from aziadamant- ployed to help understand the relationship between struc-
anes, which form very strong ICs with β-CyD but are never- ture and reactivity. The assemblies of the ICs of ada-
theless positioned within the crystal lattice to form az- mantane azides 1 and 5 with β-CyD could be inferred from
ines.[ For the 1:2 complexes with α-CyD any kind of di- 2-D ROESY experiments, which were conducted in D O at
10]
2
merization becomes impossible for aziadamantanes as well 300 K (Figures 1 and 2). The spectra for 1 and 5 showed
as for 1 and 5. Without recourse, imine 2 is forced to react cross-peaks with the inner β-CyD protons H3 and H5,
with fortuitous water molecules co-entrapped in CyD to af- which are indicative of true inclusion. Thus, a straightfor-
ford 3 as the sole product in high yield. It should be noted
that in aqueous alcohol, a protic solvent, photolysis of 1
[
9]
also yields 3.
Photodecomposition of 2-azidoadamantane (5) affords
3
,8
the imine
6
(4-azatricyclo[4.3.1.1 ]undec-4-ene, see
Scheme 2), which neither reacts with water nor does it di-
merize. Due to the presence of an α-H atom, however, 5
also forms the exocyclic imine 2-iminoadamantane (7) to a
minor extent. This hydride migration occurs either in one
step or in two steps involving the intermediate 2-adamant-
anylnitrene. Imine 7 is readily hydrolyzed during aqueous
work-up to give adamantanone (8).[
11]
In contrast to that of 1@CyD, the photolysis of 5@CyD
essentially led to the same product distribution of 6 and 8
(Table 1, entries 7, 8) as that of the classical solution chem-
istry (Table 1, entry 6). Thus, neither α- nor β-CyDs alter
the reaction’s outcome.
ESI MS and HPLC analyses of the CyD fraction from
the photodecomposition of 1@CyD and 5@CyD ICs
clearly revealed the absence of modified CyDs. Conse-
quently, there is no interaction between the reactant and
2
Figure 1. 250 MHz 2-D ROESY spectrum of 1@β-CyD in D O.
its host molecule. This is truly unlike the decomposition Mixing time 600 ms.
1250
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 1249–1255

Photochemical Decomposition of Azidoadamantanes
ward proposal for the geometry of 1@β-CyD could be 2-D ROESY spectrum (Figure 4). Further analysis using
made (Figure 3). In contrast, interpretation of the 2-D single-crystal X-ray diffraction techniques was warranted.
ROESY spectrum of 5@β-CyD did not suggest a single ge-
Colorless prismatic crystals of 5@β-CyD were obtained
ometry of this IC. Two possible orientations of the guest after cooling a hot aqueous:ethanolic solution of 5 and
molecule could account for the observed cross-signals in the β-CyD. They were of the composition 2β-CyD·
0
.75C H N ·21.5H O and could be assigned to the tri-
10 15 3 2
Figure 5. Single-crystal X-ray structure of 5@β-CyD. Hydrogen
and water molecules were removed for clarity. Two crystallographi-
cally independent β-CyD molecules B and D are present in the unit
[
13]
cell. The guest molecule C is disordered over two positions.
2
Figure 2. 600 MHz 2-D ROESY spectrum of 5@β-CyD in D O.
Mixing time 300 ms.
2
Figure 3. Proposed geometry of 1@β-CyD in D O based on 2-D
ROESY measurements.
Figure 6. (a) B3LYP/6-31G(d)-optimized geometry of 1, (b)
HOMO, and (c) LUMO. Frontier orbitals involved in the TD/
B3LYP/6-31G(d)-calculated transition at 283 nm based on B3LYP/
6-31G(d)-optimized geometry (isosurface value 0.07).
Figure 7. B3LYP/6-31G(d)-optimized geometries of 5: (a) and (b)
ground state geometric conformers, and (c) C symmetric transition
state between the two enantiomeric conformers of (a).
Figure 4. Proposed geometries of 5@β-CyD in D
ROESY measurements.
2
O based on 2-D
s
Eur. J. Org. Chem. 2011, 1249–1255
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1251

U. H. Brinker, P. Walla, D. Krois, V. B. Arion
FULL PAPER
clinic non-centrosymmetric space group P1 (Figure 5). The its C -symmetric geometry (Figure 7, c), because this is the
s
unit cell consists of two crystallographically independent time-averaged geometry experienced in solution. This
molecules of β-CyD (Figure 5, B and D). The first one ac- means that the molecule is rendered achiral due to the
commodates a molecule of 5 with ca. 25% occupancy (Fig- flipping of the azido group between the two enantiomeric
ure 5, A), and the second, a molecule of 5, which is disor- conformers depicted in Figure 7 (a).
dered over two positions with site occupation factors
.5:0.5, with ca. 50% occupancy (Figure 5, C). The CyD electronic transition above λ = 220 nm was found by TD
molecules form channels with the dimers arranged in a and CIS methods with maxima at λ ≈ 280 nm, independent
For the two azidoadamantanes investigated, only one
0
[
13]
head-to-head type fashion (Figure 5, for details see ref. ). of the extent of configuration interaction (other transitions
Guest molecule A is entrapped between the wider apertures are not shown, Tables 2 and 3). As illustrated in the case of
of CyDs D and B, which are mutually oriented in a head- 1 (Figure 6, b, c), the frontier orbitals involved in the 283-
to-head fashion. The azido group of A penetrates deeply nm transition (Table 2, TD method) are π –π * in nature.
z
y
into the cavity of B. On the other hand, the disordered guest The TD calculation corroborates the former finding of a
C is not really confined, but only intercalated between B “perpendicular“ π –π * transition in alkyl azides and azo-
y
x
and D, which, in this case, are tail-to-tail oriented, e.g., the imide.[18] As inferred from the transition dipole moment
adamantane framework of C is located at the narrower ap- components shown in Tables 2 and 3, the transitions
erture of CyD D.
around 280 nm are z-polarized (perpendicularly to the C–
Computations were performed to complement the X-ray N–N plane, where the azido group is positioned) for the
structure (Figure 5). The gas-phase geometries of 1 (Fig- investigated geometries of 1 and 5. Both methods, CIS and
ure 6) and 5 (Figure 7) were optimized with density func- TD, afforded similar results in terms of transition dipole
tional theory (DFT), using Becke’s[ three-parameter hy- moment vectors and energies of the π –π * transition.
14]
z
y
brid method and the exchange functional of Lee, Yang, and
The strengths of azidoadamantane (1 and 5):(α- and β-)
[
15]
Parr (B3LYP)
for a 6-31G(d) basic set. According to CyD ICs were investigated using ICD in aqueous:ethanolic
DFT, azide 5 can settle into two geometric minima (Fig- solutions at 293 K. Complexation of both 1 and 5 by β-
ure 7, a, b) with 5a being 3 kcalmol–1 more stable than 5b. CyD[19] produced negative signs of the ICD Cotton effect
In crystalline 5@β-CyD, the guest adopts the more stable with a minimum at 285 nm (Figures 8 and 9). It should be
conformation of 5a only.
noted that, due to the bimodal inclusion mode of 5@β-
Single-point calculations provided the UV/Vis electronic CyD, interpretation of the negative ICD bands of 5@β-
[
20]
transition dipole moment vectors necessary for ICD spectra CyD is complicated (vide infra).
The observed concen-
interpretation (vide infra). These single-electron vertical tration dependencies were used to elucidate the types of ICs
[
21]
transitions of 1 and 5 were computed by two methods, i.e., formed. The linear Scatchard plots
for both azidoada-
and mantane@β-CyD ICs support 1:1 stoichiometries (Fig-
time-dependent DFT (TD)[ (Tables 2 and 3). The single- ures 10 and 11). Evaluation of the data also led to the deter-
[16]
single-excitation configuration interaction (CIS)
17]
[
22,23]
point calculations of 5 (Table 3) were performed based on mination of association constant (K ) values.
The
a
Table 2. CIS(FC)/6-31G(d) and TD/B3LYP/6-31G(d) vertical transitions for 1 at the B3LYP/Ͼ6-31G(d) ground-state optimized geometry
Figure 6). Only the highest wavelength transition is shown.
(
Method
Transition energy
Orbitals involved Orbital coefficient Oscillatory strength Transition dipole moment components
λ [nm]
f
x
y
z
CIS
281
28 Ǟ 49
–0.10531
0.10877
–0.13772
0.64961
0.11208
0.68405
0.0001
–0.0002
0.0004
–0.0249
4
4
4
4
0 Ǟ 49
6 Ǟ 49
8 Ǟ 49
8 Ǟ 51
TD
283
48 Ǟ 49
0.0000
–0.0005
0.0001
–0.0205
Table 3. CIS(FC)/6-31G(d) and TD/B3LYP/6-31G(d) vertical transitions for 5 at the B3LYP/6-31G(d) transition-state optimized geometry
Figure 7, C). Only the highest wavelength transition is shown.
(
Method Transition energy
Orbitals involved Orbital coefficient Oscillatory strength
Transition dipole moment components
λ [nm]
f
x
y
z
CIS
280
27 Ǟ 49
–0.10677
0.13669
–0.15303
0.63976
0.12317
0.68331
0.0001
0.0000
0.0000
–0.0229
4
4
4
4
0 Ǟ 49
5 Ǟ 49
8 Ǟ 49
8 Ǟ 51
TD
283
48 Ǟ 49
0.0000
0.0000
0.0000
–0.0194
1252
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 1249–1255

Photochemical Decomposition of Azidoadamantanes
higher value of K (1@β-CyD) = 20240Ϯ1000 m–1 reveals
a
that 1 is accommodated more tightly within the host cavity
–
1
than is 5, cf., K (5@β-CyD) = 7450Ϯ400 m .
a
Figure 11. Scatchard plot for determination of K
O/EtOH 80:20 (v/v) at 293 K.
a
of 5@β-CyD in
(5@β-CyD) =
H
2
=
K
a
–
1
7450Ϯ400 m .
ICs of both 1 and 5 with α-CyD ICs were determined by
NMR and microanalysis, which confirm 1:2 stoichiometries
Figure 8. Concentration dependency for ICDs of 1@β-CyD in
H O/EtOH = 80:20 (v/v) at 293 K.
2
(see Table S1 of Supporting Information). A determination
of K values in these cases is very difficult and can generally
a
only be conducted by making certain restricting assump-
[
22a,23]
tions.
Figure 9. Concentration dependency for ICDs of 5@β-CyD in
O/EtOH = 80:20 (v/v) at 293 K.
H
2
Figure 12. Concentration dependency for ICDs of 1@(α-CyD)
2
2
in
H
O/EtOH = 90:10 (v/v) at 293 K.
Figure 10. Scatchard plot for the determination of K
a
of the 1@β-
CyD IC in H O/EtOH = 80:20 (v/v) at 293 K. K (1@β-CyD) =
2
a
–1
2
0240Ϯ1000 m .
The ICD spectrum for the IC of 1 and α-CyD produced
Figure 13. Concentration dependency for ICDs of 5@(α-CyD)
2
2
in
two bands – a positive band with a maximum at 283 nm
and a negative one with a minimum at 317 nm (Figure 12).
Yet, that of 5 and α-CyD exhibited only one negative band
H O/EtOH = 90:10 (v/v) at 293 K.
According to 2-D ROESY measurements the ada-
with a minimum at 285 nm (Figure 13). Treatment of the mantane framework in 1@β-CyD is located above the host
ICD data of Figure 12 and Figure 13 by Scatchard plots led cavity while the azido group deeply penetrates into the β-
to a nonlinear phenotype (not shown), indicating an uneven CyD cavity. Harata’s rule predicts a negative ICD when the
stoichiometry. Indeed, the empirical compositions of the transition dipole moment of the guest chromophore is
Eur. J. Org. Chem. 2011, 1249–1255
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1253

U. H. Brinker, P. Walla, D. Krois, V. B. Arion
FULL PAPER
aligned perpendicular to the principal axis of the CyD cav- the organic azide and to protect against formation of clumps. The
ity.[24] The development of this rule was based on aromatic
π–π* transitions and later was validated for the d-d transi-
beaker was wrapped in aluminium foil to protect the starting mate-
rial from light. The white suspension was filtered using a sintered
funnel (porosity #4). The complex was dried at room temperature
[
25]
tions of ferrocenes
and n–π* transition of the diazirine
in a desiccator over CaCl
stoichiometry was inferred from integrals of H NMR spectra of
complexes recorded in [D
2
for 1 d at P = 0.5 Torr. The approximate
[
23]
[26]
chromophore,
azoalkanes,
and π–π* transitions of the azo group in azo
Here, the rule is being applied to the azide π –π *
conjugated
alkyl
1
[
27]
ketones,
dyes.
[29]
6
]DMSO.
The exact stoichiometries
[
28]
z
y
were determined by microanalysis based on nitrogen content and
are summarized in Table 1 (see Supporting Information).
[
17]
transition. Thus, based on the geometry depicted in Fig-
ure 3, the azido chromophore should produce a negative
ICD band, since the transition dipole moment vector of its
Photolyses of Solid Cyclodextrin Complexes: 100–300 mg of the so-
lid complexes was weighed into a 250-mL round-bottom flask and
dispersed over the entire inner surface. Using a manifold, the flask
was evacuated and argon was allowed to replace the air (3ϫ). The
flask was closed quickly with a septum pierced with two cannulas
285-nm band is perpendicularly oriented to the C–N–N
bond of the azido group (Table 2). Since negative ICD
bands with a minimum at 285 nm were actually observed
(Figure 8), the geometry proposed based on the 2-D (one being the inlet for argon and the other one the outlet). After
ROESY technique correlates well with the ICD spectra.
a short flow of argon, the needles were removed and the septa
wrapped with parafilm, then aluminum foil, and parafilm again to
protect the septa against destruction by UV light. The rotating
flask was immersed into an ultrasonic bath with circulating water
Conclusions
(
16–24 °C). The photolyses of the complexes were conducted by
placing a medium-pressure mercury lamp (TQ718-Z4, 700 W,
doped with FeI , glass jacket) beside the flask at a distance of 10–
0 cm. The photolyses took 1–2 d depending on the amount of
The product distributions from the photolyses of azi-
doadamantanes 1 and 5 included within CyD cavities were
investigated in order to gain insight into the influence of
supramolecular encapsulation. Upon photolysis of 1@β-
2
2
complex used. Occasionally, during the photolysis, a short sonic-
ation was applied to redistribute the solid complex over the walls
of the flask, thereby exposing a fresh surface of complex towards
the UV light. The low-molecular weight adamantane derivatives
CyD as well as 1@(α-CyD) , only amino alcohol 3 was
2
formed. The lack of dimer 4 may be ascribed to classical
solution chemistry, which entails hydrolysis of the interme- within the cyclodextrins were recovered by dissolving the product
diary bridgehead imine 2 embedded within the CyD cavity. residue in water (100 mL) and dichloromethane (50 mL) and sub-
Since azide 5 does not lead to a reactive imine, its incarcera- jecting the mixture to continuous extraction with an apparatus for
extracting liquids of higher density. After 24 h, the dichlorometh-
ane was replaced by a new portion to afford the first fraction and
tion did not alter its usual chemistry.
Investigation of the 5@β-CyD supramolecular structure
after 48 h a second dichloromethane extract was collected. In this
by 2-D ROESY NMR and single-crystal X-ray analysis re-
way, the evaporation of potentially volatile products could be ascer-
vealed that 5 experiences a bimodal disposition within the
tained. The dichloromethane solutions were analyzed by GC–MS
cavity of β-CyD. ICD was used to determine the K values
of the ICs and to correlate their dispositions with 2-D
a
and the yields of the components were quantified by a GC-FID
calibrated with (+)-camphor as an internal standard. Table 2 (see
Supporting Information) summarizes the GC-FID data. After con-
ROESY NMR studies. In H O/EtOH = 8:2, 1-azidoada-
2
mantane (1) is bound more strongly to β-CyD than is 2- tinuous extraction, water from the aqueous phase was evaporated
azidoadamantane (5). Azide 1 is nearly three times more in vacuo and analyzed for the presence of possible insertion or
strongly bound than azide 5 and is accommodated more modification products formed by the reaction of CyD with ada-
mantyl nitrene. All of the obtained CyD fractions, exhibited iden-
tightly within the cavity. This correlates also with the non-
tical ESI-MS spectra and proved to be pure α- (see Figure S1 in
the Supporting Information) or β-CyD (Figure S2).
homogeneous orientations of 5 within β-CyD. The orienta-
tion of the transition dipole moment vector of the π –π *
z
y
transition of the azido group was derived from DFT calcu- The CyD fraction from the photolysis of azidoadamantane@α-
CyD complexes were analyzed by RP-HPLC and LC-MS. No sig-
lations. Subsequently, Harata’s rule was applied to the ge-
nals corresponding to the sum of adamantyl nitrene and α-CyD
ometry of 1@β-CyD proposed by the 2-D ROESY tech-
masses or related masses were found using the latter analysis. Ac-
nique and a close match was found between the experimen-
cording to the RP-HPLC-RI analysis, the CyD fractions from the
photolysis of the azidoadamantane:β-CyD complexes were found
to be unaltered β-CyD.
tal and predicted ICD signs. A generalization of this sym-
metry rule applicability on the transitions of the azido
group would, however, require further elaborative and ex-
tensive analyses.
Determination of Association Constants by ICD Titration: UV/Vis
and CD spectra were recorded with a Lambda 16 spectrometer and
a CD6 circular dichrograph, respectively, in thermostatted quartz
cuvettes (10 cm path length). The ICD titration was done in H
EtOH, 80:20 at 293 K by the dilution technique and subsequently,
an iterative Scatchard plot for the K determinations of 1:1 stoi-
chiometric complexes of azidoadamantanes with β-CyD was
LINEST function was used for the assessment of the
standard deviation of the linear Scatchard plot.
2
O/
Experimental Section
a
General Procedure for the Preparation of Cyclodextrin Complexes:
A saturated cyclodextrin solution (5 equiv.) was placed into a high-
walled beaker and azidoadamantane in ether was added in small
amounts. The contents of the beaker were magnetically stirred and
argon was simultaneously bubbled into the suspension through a
needle for 8 h. Furthermore, the mixture was sonicated to disperse
used.[
22,23]
Supporting Information (see footnote on the first page of this arti-
cle): ESI mass spectra, ICD titration data, and computations.
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2011, 1249–1255

Photochemical Decomposition of Azidoadamantanes
[
[
12] D. Krois, M. M. Bobek, A. Werner, H. Kählig, U. H. Brinker,
Org. Lett. 2000, 2, 315.
13] CCDC-802794 contains the supplementary 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.
Acknowledgments
This work was financially supported by the Fonds zur Förderung
der wissenschaftlichen Forschung in Österreich (project number
P12533-CHE). We thank Mr. A. Roller, Institut für Anorganische
Chemie, Universität Wien, for performing X-ray measurements.
[
[
[
14] A. D. Becke, J. Chem. Phys. 1993, 98, 5648.
15] C. Lee, W. Yang, R. G. Parr, Phys. Rev. B 1988, 37, 785.
16] J. B. Foresman, M. Head-Gordon, J. A. Pople, M. J. Frisch, J.
Phys. Chem. 1992, 96, 135.
[
1] a) Organic Azides: Syntheses and Applications (Eds.: S. Bräse,
K. Banert), John Wiley & Sons, New York, 2010; b) S. Bräse,
C. Gil, K. Knepper, V. Zimmermann, Angew. Chem. Int. Ed.
[
[
17] M. E. Casida, C. Jamorski, K. C. Casida, D. R. Salahub, J.
Chem. Phys. 1998, 108, 4439.
18] W. D. Closson, H. B. Gray, J. Am. Chem. Soc. 1963, 85, 290.
The arbitrary designation of π orbitals in terms of reference
axes as x, y, z in our system are y, z, x, respectively.
19] Handbook of Cyclodextrins and Their Complexes (Ed.: H. Dod-
ziuk), Wiley-VCH, Weinheim, Germany, 2006.
2
005, 44, 5188; c) A. Hassner, in: Azides and Nitrenes: Reactiv-
ity and Utility (Ed.: E. F. V. Scriven), Academic, New York,
984, pp. 35–76.
1
[
[
[
2] a) M. S. Platz, in: Reactive Intermediate Chemistry (Eds.: R. A.
Moss, M. S. Platz, M. Jones Jr), John Wiley & Sons, Hoboken,
NJ, 2004, pp. 501–559; b) E. F. V. Scriven, Azides and Nitrenes:
Reactivity and Utility, Academic, New York, 1984; c) C.
Wentrup, Reactive Intermediates, John Wiley & Sons, New
York, 1984; d) W. Lwowski, Nitrenes, John Wiley & Sons, New
York, 1970.
20] For calculations of ICD spectra and subsequent correlations
with ICD, see: a) G. Marconi, B. Mayer, Pure Appl. Chem.
1
997, 69, 779; b) B. Mayer, X. Zhang, W. M. Nau, G. Marconi,
J. Am. Chem. Soc. 2001, 123, 5240.
[
[
21] C. R. Cantor, P. R. Schimmel, Behavior of Biological Macro-
molecules (Ed.: W. H. Freeman), San Francisco, 1980, part III,
p. 849.
22] a) D. Krois, U. H. Brinker, J. Am. Chem. Soc. 1998, 120, 11627;
b) D. Krois, U. H. Brinker, Circular Dichroism of Cyclodextrin
Complexes, in: Handbook of Cyclodextrins and Their Complexes
(Ed.: H. Dodziuk ), Wiley-VCH, Weinheim, Germany, 2006,
pp. 289–298.
[
3] a) W. Lwowski, Ann. N. Y. Acad. Sci. 1980, 346, 491; b) E. L.
Vodovozova, Biochem. (Moscow) 2007, 72, 1.
[4] G. Wagner, V. B. Arion, L. Brecker, C. Krantz, J.-L. Mieusset,
U. H. Brinker, Org. Lett. 2009, 11, 3056.
[
[
[
5] K. A. Connors, Chem. Rev. 1997, 97, 1325.
6] J. Szejtli, Chem. Rev. 1998, 98, 1743.
7] a) U. H. Brinker, R. Buchkremer, M. Kolodziejczyk, R. Kupfer,
M. Rosenberg, M. D. Poliks, M. Orlando, M. L. Gross, Angew.
[23] M. M. Bobek, D. Krois, U. H. Brinker, Org. Lett. 2000, 2, 1999.
[24] K. Harata, H. Uedaira, Bull. Chem. Soc. Jpn. 1975, 48, 375.
Chem. Int. Ed. Engl. 1993, 32, 1344; b) For reviews, see: Mieus- [25] a) A. Harada, S. Takahashi, Chem. Lett. 1984, 2089; b) A.
set, J.-L.; Brinker, U. H. Encapsulation of Reactive Intermedi-
ates. in: Molecular Encapsulation: Organic Reactions in Con-
strained Systems, U. H Brinker, J.-L. Mieusset, (Eds.), Wiley:
Chichester, 2010, pp. 269–308; c) M. G. Rosenberg, U. H.
Brinker, Eur. J. Org. Chem. 2006, 5423–5440; d) M. G. Rosen-
berg, U. H Brinker, Carbenes Generated within Cyclodextrins
and Zeolites. in: Adv. Phys. Org. Chem. J. P. Richard (Eds.),
Academic: New York 2005, vol. 40, pp. 1–47.
Harada, Y. Hu, S. Yamamoto, S. Takahashi, J. Chem. Soc.,
Dalton Trans. 1988, 729; c) V. I. Sokolov, V. L. Bondareva, I. F.
Golovaneva, J. Organomet. Chem. 1988, 358, 401; d) V. I. Soko-
lov, V. L. Bondareva, I. F. Golovaneva, Metalloorganicheskaya
Khimiya 1988, 1, 716) (for the Engl. translation, see: Or-
ganomet. Chem. USSR 1988, 1, 400e) N. Kobayashi, M.
Opallo, J. Chem. Soc., Chem. Commun. 1990, 477.
[26] H. Bakirci, X. Zhang, W. M. Nau, J. Org. Chem. 2005, 70, 39,
[
[
8] Complete hydrolysis to 7-(aminomethyl)bicyclo[3.3.1]nonan-3-
one was not observed.
and references cited therein.
[27] G. M. Bonora, R. Fornasier, P. Scrimin, U. Tonellato, Car-
bohydr. Res. 1986, 147, 205.
9] a) H. Quast, P. Eckert, Justus Liebigs Ann. Chem. 1974, 1727;
b) I. R. Dunkin, C. J. Shields, H. Quast, B. Seiferling, Tetrahe-
dron Lett. 1983, 24, 3887; c) J. Michl, G. J. Radziszewski, J. W.
Downing, K. B. Wiberg, F. H. Walker, R. D. Miller, P. Kovacic,
M. Jawdosiuk, V. Bonacic-Koutecky, Pure Appl. Chem. 1983,
[28] a) M. Suzuki, M. Kajtar, J. Szejtli, M. Vikmon, E. Fenyvesi,
L. Szente, Carbohydr. Res. 1991, 214, 25; b) Y. Liu, Y.-L. Zhao,
H.-Y. Zhang, Z. Fan, G.-D. Wen, F. Ding, J. Phys. Chem. B
2004, 108, 8836.
55, 315.
[29] The inclusion complex is fully dissociated in dilute DMSO
1
[
10] a) D. Krois, L. Brecker, A. Werner, U. H. Brinker, Adv. Synth.
Catal. 2004, 346, 1367; b) W. Knoll, M. M. Bobek, G. Giester,
U. H. Brinker, Tetrahedron Lett. 2001, 42, 9161.
solutions and the H NMR spectrum may be interpreted as a
sum of proton spectra of the neat components.
Received: November 12, 2010
[
11] T. Sasaki, S. Eguchi, N. Toi, J. Org. Chem. 1979, 44, 3711.
Published Online: January 12, 2011
Eur. J. Org. Chem. 2011, 1249–1255
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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