Synthesis, metal ion binding, and photochromic properties of benzo- and naphthopyrans annelated by crown ether moieties

Article abstract of DOI:10.1016/j.tet.2012.07.029

Combining a photochromic chromene with a crown ether moiety results in systems in which photochromism and ionophoric properties could significantly influence each other. In this paper, we report the synthesis of several chromenes annelated by 15(18)-crown

Full text of DOI:10.1016/j.tet.2012.07.029

Tetrahedron 68 (2012) 7873e7883
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis, metal ion binding, and photochromic properties of benzo- and
naphthopyrans annelated by crown ether moieties
,
b
c
c
Sergey V. Paramonov a , Vladimir Lokshin , Artem B. Smolentsev , Evgeni M. Glebov ,
*
Valeri V. Korolev c, Stepan S. Basok d, Konstantin A. Lysenko a , Stephanie Delbaere , Olga A. Fedorova
a A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilova St., 119991 Moscow, Russian Federation
,
y
e
a,
y
ꢀ
b
ꢀ
Centre Interdisciplinaire de Nanoscience de Marseille (CINaM, CNRS UMR 7325), Aix-Marseille Universite, 163 Av. de Luminy, 13288 Marseille, France
c Institute of Chemical Kinetics and Combustion, Siberian Branch of Russian Academy of Sciences, 3 Institutskaya St., 630090 Novosibirsk, Russian Federation
d A.V. Bogatsky Physico-Chemical Institute, National Academy of Science of Ukraine, 86 Lustdorfskaya doroga, 650080 Odessa, Ukraine
e
ꢀ
Universite Lille Nord de France, CNRS UMR 8516, UDSL 3 rue du Professeur Laguesse BP83, 59006 Lille, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Combining a photochromic chromene with a crown ether moiety results in systems in which photo-
chromism and ionophoric properties could significantly influence each other. In this paper, we report the
synthesis of several chromenes annelated by 15(18)-crown-5(6) ethers. The approach involves the
building of the photochromic fragment upon the initial crown ether via phenols. The two main routes for
chromene preparation are discussed. The complex formation of the synthesized photochromic crown-
containing naphthopyran with magnesium(II) and barium(II) cations was studied. The kinetic behavior
of the colored form of the compound is affected by complex formation.
Received 28 February 2012
Received in revised form 17 June 2012
Accepted 10 July 2012
Available online 20 July 2012
Keywords:
Chromenes
Crown ether
Ó 2012 Elsevier Ltd. All rights reserved.
Synthesis
BaeyereVilliger oxidation
Hosteguest complexes
Binding constants determination
Photochromism
1. Introduction
assemblies,4 and biological photoswitching systems5 have also
been realized.
Photochromic systems have the ability to undergo a reversible
transformation between two states giving rise to different ab-
sorption spectra, induced, at least in one direction, by electro-
magnetic radiation.1 If one of the states absorbs in the visible region
under appropriate conditions, a noticeable, reversible change of
color occurs as a consequence of the transformation. Photo-
transformations of this type open a wide field of potential appli-
cations in modern technologies, such as optical switches,
memories, and molecular electronics.2 In recent research, the
photochemically-reversible construction of nanoarchitectures,3 the
introduction of photochromic molecules into supramolecular
Attaching a crown ether moiety to a photochromic molecule
leads to substantial extension of the possible practical usage of
such systems.6 Different chromenes linked to a macrocyclic
fragment have already been reported.7 However, there is a lack of
information concerning the synthesis of photochromes annelated
by a crown ether moiety. Meanwhile, we believe that annelation
of the ionophoric moiety should lead to a more considerable
mutual influence of the two processes that occur in the
molecule, namely complex formation and the photoinduced
transformation.
Recently, we reported for the first time the synthesis of angular
chromenes annelated by 15(18)-crown-5(6) ethers 1a,b.8 In the
present paper, we extend the series and describe new linear
chromenes 2 and naphthopyran 3. The presented synthesis in-
volves general routes to photochromic systems annelated by
a crown ether fragment. For naphthopyran 3, we have also studied
photochromic properties and complex formation with magnesiu-
m(II) and barium(II) cations.
* Corresponding author. Tel.: þ7 499 135 80 98; fax: þ7 499 135 50 85; e-mail
addresses: paramonov@ineos.ac.ru (S.V. Paramonov), fedorova@ineos.ac.ru (O.A.
Fedorova).
y
Tel.: þ7 499 135 80 98; fax: þ7 499 135 50 85.
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.07.029

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S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
2. Results and discussion
2.1. Synthesis
The reaction of naphtho-15-crown-5 or benzo-18-crown-6 with
Eaton’s reagent afforded crystalline ketone 9b (90%) or 10 (90%)
[83% and 80% for 9a and 9b, respectively, in lit.9]. Oxidation by
organic peracids10 converted 9, 10 to carboxylic esters 11, 12 (the
BaeyereVilliger oxidation). For this kind of reaction, peracetic acid is
generally used as oxidizing agent, esters 11 being prepared with
good yields (11a, 82% and 11b, 65%).9 In our case, however, m-
chloroperbenzoic acid (m-CPBA) turned out to be the better choice
due to its greater stability at room temperature, leading to mod-
erate yields (11b, 70% and 12, 40%). In most cases, the yields of the
reaction are affected by (i) unstable oxidizing agent, (ii) multiple
oxidizing side reactions, and (iii) very close Rf values of the starting
compound and the product that makes it difficult to isolate the
Phenols or naphthols are known to be suitable precursors for
chromene synthesis.1 However, only a small number of crowned
phenols are commercially available. In most cases, the corre-
sponding benzo- or naphthocrown ether is transformed into the
hydroxy-substituted derivative. In addition, certain substitution
requires the application of specific synthetic approaches involving
crown ether constructing upon the phenol system, e.g., phenols
4.8
latter from the reaction mixture by column chromatography.
Among the side-products of ketone 10 oxidation, quinoid derivative
13 was identified (consult Supplementary data for details).
In the synthesis of compounds 2 and 3, the starting phenols 5
and naphthol 6 were synthesized from the available benzo-15(18)-
crown-5(6) and naphtho-15-crown-5 ethers. A modification of the
approach firstly reported by Wada et al.9 was used. The synthesis
was based on a selective acylation of benzene (7) or naphthalene
(8) derivative, followed by the restoration of ketones 9 and 10 into
ester functions, and further base hydrolysis of esters 11, 12 to give
crown-containing phenols 5 or naphthol 6 (Scheme 1).
Scheme 1. The preparation of crown-containing phenols 5 and 6.

S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
7875
Further treatment of esters 11 and 12 with 10% aqueous NaOH
resulted in phenols 5b (50%) and 6 (60%) [93% and 82% for 5a and
5b, respectively, in lit.9]. The X-ray structure of new naphthol 6 is
presented in Fig. 1. Compound 6 crystallizes as a solvate with water
ring closure. Another approach (Procedure B) suggests condensa-
tion of phenols or naphthols with b-phenylcinnamaldehyde in the
presence of titanium(IV) ethoxide (Scheme 2).12
Procedure A was originally applied for preparation of carbocy-
clic chromenes and Procedure B was developed for heterocyclic
chromene synthesis. The latter may be successfully used for car-
bocyclic chromenes, too. However, in the case of crown containing
chromenes, Procedure B has significant advantages despite the
early reports of its lack of success.13 The main disadvantages of
Procedure A are the side-processes involving PTSA interactions
with reagents that diminish yields and make the purification of
the product difficult. In the presence of PTSA the diphenylpro-
pargylic alcohol transforms into
b-phenylcinnamaldehyde via
a MeyereShuster rearrangement mechanism (Scheme 3, pro-
cedure A), the aldehyde being isolated in this study in negligible
amount. Apparently, the acidic conditions also lead to partial hy-
drolysis of the crown ether resulting in impurities containing
different polyether substitution that significantly hinder the
product isolation (Scheme 2, procedure A). On the contrary, Pro-
cedure B does not have these disadvantages. It allows higher
yields generally due to easier separation of the reaction mixture.
However, a few products of side reactions involving the aldehy-
de and titanium(IV) ethoxide interaction probably via a Meer-
weinePonndorfeVerley reduction mechanism are suggested
(Scheme 3, procedure B), and 3,3-diphenylprop-2-en-ol has been
separated out. Nevertheless these reactions do not affect consid-
erably the main product isolation.
Fig. 1. The general view of 6 in representation of atoms by thermal ellipsoids (p¼50%).
and CH2Cl2 molecules. The bond lengths and angles in 6 are close to
those expected. The water molecule serves both as a proton donor
and acceptor participating in H-bonds with oxygen atoms of the
ꢁ
crown ether (O/O 2.817e3.052(7) A) and with the hydroxyl group
ꢁ
(O/O 2.730(6) A) resulting in the formation of the infinite helix
consisting of alternating 6 and water molecules and directed along
crystallographic axis b. The CH2Cl2 molecule disordered over three
positions is situated within the folds of the above-mentioned helix
and is likely to participate in a number of weak CeH/O and
CeH/Cl contacts.
2H-Chromene derivative preparation procedures are based on
a ‘one-pot reaction’ starting from a suitable phenol or naphthol. In
our research, two different methods were used. Procedure A in-
volves the acid-catalyzed reaction of phenols or naphthols
with propargylic alcohol.11 The reaction proceeds via Claisen
rearrangement of alkynyl aryl ethers resulting from naphthol
‘O-alkylation’, followed by [1,5]H sigmatropic shift and electrocyclic
The yields for chromene preparation are summarized in Table 1
and they are usual for chromene synthesis. The structures of the
products were confirmed by NMR spectroscopy and elemental
analysis. The X-ray investigation was performed for compound 1a
(Fig. 2). The conformation of the oxygen containing cycle can be
described as a distorted sofa with the deviation of O(1) and C(10)
ꢁ
atoms from the mean plane of the other atoms by 0.65 and 0.30 A.
According to the bond length distribution in the aromatic cycle as
well as values of lengths for C(6)eC(7) and C(5)eC(6) bonds
ꢁ
ꢁ
(1.325(2) A and 1.447(2) A, respectively) one may conclude that the
Scheme 2. The principal routes to chromenes.

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S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
metal cations.14 In our study, we chose Mg2þ and Ba2þ, which
have different ionic radii. The stoichiometry and stability constants
of the complexes were determined by two common optical
methods, namely Job’s plot and spectrophotometric titration.15
Fig. 3a demonstrates the formation of the complex between
naphthopyran 3 and Mg2þ. The isosbestic points (307 and 360 nm,
Fig. 3a) supports the assumption that only two forms containing
the chromene molecule coexist in solution. The Job’s plot method
was used to determine the stoichiometry of the complexes.15a
According to the Job’s plot the ratio of naphthopyran 3 to Mg2þ in
the complex is 1:1 (Fig. 3b). Taking into account the radius of the
14
15-crown-5-ether cavity (0.85 A) and the ionic radius of Mg2þ
ꢁ
(0.72 A),14 we suggest the formation of an inclusive 1:1 complex, in
ꢁ
which the cation is located inside the crown ether. The stability
constant of the complex was determined from the observed ab-
sorbance changes in the course of the titration (Fig. 3c, Table 2)
considering the following equilibrium:
½LMꢀ
;
L þ M%LM K11
¼
½Lꢀ½Mꢀ
where K11 corresponds to the stability constant of the 1:1 complex;
[L], [M], and [LM] denote the equilibrium concentration of the
Scheme 3. Main side reactions of the methods.
Table 1
The chromenes preparation yields
1a n¼1
1b n¼2
2a n¼1
2b n¼2
3
Procedure A
Procedure B
<1%
30%
<1%
30%
4%
20%
19%
25%
16%
29%
C(6)eC(7) double bond practically does not participate in conju-
gation with the aromatic system. The analysis of intermolecular
contacts revealed that all of them correspond to weak van-der-
Waals type contacts.
metal cations, naphthopyran (ligand), and their 1:1 complex, re-
spectively. The data was analyzed by numerical methods described
elsewhere16 (consult Supplementary data for details).
In the case of barium cations, the UVevis spectra during titra-
tion showed no isobestic points indicating the existence of more
than one complex in the solution (Fig. 4a). Analysis of the experi-
mental data (Fig. 4b) revealed the presence of two types of com-
plex, namely with ligand to metal (L/M) composition equal to 1:1
and 2:1. The stability constants were determined considering the
following equilibria (Fig. 4b, Table 2):
2.2. Complex formation
The crown ether fragment in the molecule of naphthopyran 3
gives it the ability to form stable complexes with alkaline-earth
½LMꢀ
;
L þ M%LM K11
¼
½Lꢀ½Mꢀ
½L2Mꢀ
LM þ L%L2M K21
¼
;
½LMꢀ½Lꢀ
where K11 and K21 correspond to the stability constants of the 1:1
and 2:1 complexes; [L], [M], [LM], [L2M] denote the equilibrium
concentration of the metal cations, naphthopyran (ligand), and
their 1:1 and 2:1 complexes, respectively. The ionic radius of Ba2þ is
14
ꢁ
1.36 A, which is larger than the crown ether cavity radius.
Therefore, we suggest the formation of an exclusive 1:1 complex, in
which the cation is located outside the crown ether fragment, and
a sandwich 2:1 complex (Scheme 4), which is stabilized by the
stacking interaction of the two chromene molecules.17,18
The magnesium 1:1 complexes are generally more stable than
the corresponding barium complexes due to the higher charge
density of the cation and its size that fits well the crown ether
Fig. 2. The general view of 1a in representation of atoms by thermal ellipsoids
(p¼50%).

S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
7877
Fig. 4. Complex formation of naphthopyran 3 with barium(II) cations in acetonitrile:
(a) spectrophotometric titration of
3 with solution of Ba(ClO4)2, cuvette 1 cm,
C3¼9ꢃ10ꢁ5 M, curves 1e5 correspond to 0, 1.5ꢃ10ꢁ5, 9ꢃ10ꢁ5, 5ꢃ10ꢁ4, and 1.5ꢃ10ꢁ3
M
of Ba(ClO4)2; (b) determination of stability constant: dots represent experimental data,
solid lines correspond to calculated dependencies of absorbance on metal cation
concentration (consult Supplementary data for details).
cavity.14 This finding as well as the formation of the sandwich
complexes with Ba2þ are consistent with our previous results with
other ligands.19
To support the UVevis studies, we performed a series of NMR
investigations of ligand 3 and its complexes with Mg2þ and Ba2þ
.
Addition of the cations led to significant changes of the spectra
evidencing complex formation. Thus, in the presence of magnesium
cations, all the signals were shifted downfield as a result of the
electron-withdrawing effect of the cation bound by the crown ether
(Fig. 5).
In the case of barium cations, the spectral changes were more
complex. At ambient temperature, the addition of the cation to
a solution of the ligand led to a significant broadening of the NMR
signals caused by fast chemical exchange of the corresponding
nuclei and cation-induced paramagnetic relaxation.20 Lowering the
temperature to ꢁ40 ꢂC allowed us to enhance the resolution and
perform the analysis. Two solutions with different ligand-to-cation
ratios were studied assuming the complexation scheme de-
termined from the UVevis experiments (Fig. 6).
Fig. 3. Complex formation of naphthopyran 3 with magnesium(II) cations in aceto-
nitrile: (a) spectrophotometric titration of 3 with solution of Mg(ClO4)2, cuvette 1 cm,
C3¼6ꢃ10ꢁ5 M, curves 1e9 correspond to 0, 6ꢃ10ꢁ6, 1.2ꢃ10ꢁ5, 1.8ꢃ10ꢁ5, 2.4ꢃ10ꢁ5
,
3ꢃ10ꢁ5, 4.8ꢃ10ꢁ5, 6ꢃ10ꢁ5, and 1.2ꢃ10ꢁ4 M of Mg(ClO4)2, respectively; (b) Job’s plot for
complex formation between 3 and Mg2þ, the sum of 3 and Mg2þ concentrations being
constant and equal to 1.2ꢃ10ꢁ4 M; (c) determination of the stability constant: dots
represent experimental data, solid lines correspond to calculated dependencies of
absorbance on metal cations concentration (consult Supplementary data for details).
The NMR spectrum of a solution with excess of Ba2þ (1:9 ratio)
reflected one dominating component, which was attributed to the
1:1 complex. All the signals were shifted downfield in the same way
we observed with magnesium cations. The spectra of the solution
with 2:1 ratio were more complex and contained two distin-
guishable families of peaks. Performing a series of 2D NMR
Table 2
Stability constants of the complexes of naphthopyran 3 with metal cations in CH3CN
Cation
log K11
log K21
Mg2þ
Ba2þ
6.0ꢄ0.3
4.2ꢄ0.4
d
4.9ꢄ0.3

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S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
opposite molecule. On the other hand, in the asymmetric complex,
such an effect should be experienced by only H-5, 6, 7, and 10, while
H-1 and H-2 should have different effects. The observed changes
(for the both components) in chemical shifts correlate better with
the asymmetric model. Protons H-6, 7, and 10 are strongly shielded,
proton H-5 is less affected (probably, due to mutually exclusive
deshielding and shielding effects). Protons H-1 and H-2 should
experience deshielding effect from the cation. Indeed, H-1 is shifted
downfield. The observed position of proton H-2 is possibly due to
specific position of the phenyl groups, which may have changed
their position in the sandwich complex so that one of the phenyls is
located close to H-2. According to this hypothesis, the two com-
ponents in the spectra correspond to different conformations of the
complex with more or less extent of rotation of the ligands rela-
tively each other.
2.3. Photochromic properties
Generally, upon irradiation with UV light, naphthopyran 3
should convert into so-called open forms (TC and TT), which ab-
sorb in visible region (Scheme 5).21 Upon cessation of irradiation,
the colored forms transform back into the initial closed form, the
process being biexponential in general. Irradiation of the solution
of 3 in acetonitrile with 313 nm (filtered light) leads to evolution of
the broad adsorption band with lmax¼425 and a shoulder at ca.
500 nm (Fig. 7a). In our case at ambient temperature, the bleaching
was characterized by a monoexponential curve (Fig. 7b), the ob-
served bleaching rate constant being 0.15ꢄ0.02 sꢁ1, which corre-
sponds to half-life time of ca.
5 s. The monoexponential
Scheme 4. Possible structures of the sandwich complexes of 3 with Ba2þ cations with
symmetric (up) and asymmetric (bottom) arrangement of the ligand molecules.
dependence could virtually indicate the formation of only one
open isomer (presumably, TC) and is most probably due to rela-
tively short irradiation time (20 s) insufficient to reach the pho-
tostationary state. Indeed, parallel NMR investigations at ꢁ40 ꢂC,
when the bleaching is significantly retarded and hence the TC
concentration becomes sufficient to trigger the TT formation,
revealed the formation of the TT form only after 30 min of irradi-
ation (Fig. 8).
The addition of metal cations to the solutions did not change the
position of the absorption maximum of the open form, yet it altered
the persistence of the colored forms. The bleaching rate constant
was increasing along with the increasing concentrations of the
experiments allowed us to assign the signals (see Supplementary
data). Similarly to the 1:1 complex, the aliphatic protons were
shifted downfield evidencing for the cation located in the crown
ether cavity. However, most of the aromatic protons were strongly
shifted upfield. Noteworthy, the shifts were essentially the same for
the both components in the spectra.
Taking into account the two possible complex structures, we
propose the following analysis of the observed data. The structure
of the symmetric complex suggests that all aromatic protons
should experience shielding effect from the aromatic system of the
metal (Fig. 9). However, after
a certain concentration, the
Fig. 5. 1H NMR spectra of 3 and its mixture with Mg2þ (C3/CMg¼1:1.5) at 20 ꢂC (CD3CN, C3¼0.001 M).

S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
7879
Fig. 6. 1H NMR spectra of 3 and its mixtures with Ba2þ (C3/CBa¼2:1 and 1:9) at ꢁ40 ꢂC (CD3CN, C3¼0.0056 M and 0.001 M, respectively).
Scheme 5. The photochromic transformation of naphthopyran 3.
dependencies evolved into plateaus, the limiting values being 0.55
and 0.37 sꢁ1 for Mg2þ and Ba2þ, respectively. Thus, complex for-
mation with metal cations leads to partial destabilization of the
open form of the naphthopyran. These results are consistent with
our previous findings for chromene 2a.18
well developed in comparison with the one which involves the
acid-catalyzed reaction of phenols with propargylic alcohol (Pro-
cedure A). However, in the case of these crown containing chro-
menes, Procedure B appeared to be more appropriate, the yields
being not high but rather good for chromene synthesis.
Unfortunately, instability of the open forms in the presence of
cations even at low temperature hindered the NMR investigations.
Still the observed characteristic peaks of the TC form were shifted
downfield evidencing for the transformation of the complexed CF
forms into the TC isomers (Fig. 10).
The complex formation and the photochromic behavior of
naphthopyran 3 were also demonstrated. The compound forms the
1:1 complexes with both magnesium(II) and barium(II) cations and
also the 2:1 sandwich complexes with barium(II) cations. The
presence of metal cations in the solution leads to partial de-
stabilization of the photoinduced form of 3 and consequently de-
creases its lifetime. Nevertheless, complexation does not shift the
maxima of absorption of the merocyanine form. This phenomenon
may be employed for creation of new photochromic sensors on
metal ions.
3. Conclusions
Here, we described the multistep synthesis of new naphtho- and
benzopyrans annelated by crown ether fragments. The main pre-
cursors are crown-containing phenols and naphthols. They could
be considered as promising for preparation of wide choice of de-
rivatives. Improved conditions of the BaeyereVilliger rearrange-
ment were found for their preparation. Another important
achievement of the synthetic approach is employing phenol or
4. Experimental section
4.1. Experimental procedures and characterization data
naphthol condensation with
b-phenylcinnamaldehyde in the
Column chromatography was performed using chromatogra-
presence of titanium(IV) ethoxide (Procedure B). This method is not
phy silica (40e63
mm particle size distribution). Melting points

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S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
Angularchromenes containing15(18)-crown-5(6)ethermoieties
1 and the synthesis of the corresponding crowned phenols 4 were
earlier reported.8 Compounds 5a,b, 9a,b, 11a,b were first described
by Wada et al.9 Benzo-crown ethers 7 are commercially available.
Naphtho-15-crown-5 ether 8 was synthesized according to lit.22
4.2. 1-(2,3,5,6,8,9,11,12-Octahydronaphtho[2,3-b][1,4,7,10,13]
pentaoxacyclopentadecine-16-yl)ethanone (10)
A modification of the previously reported procedure23 was used.
Commercially available Eaton’s reagent (ca. 8 ml that corresponds
to 6.28 mmol of phosphorus(V) oxide) and acetic acid (0.20 ml,
3.45 mmol) were mixed at room temperature. Then naphtho-15-
crown-5 ether (1 g, 3.14 mmol) was added. The reaction mixture
was stirred at room temperature for ca. 6 h and then poured into
water. The suspension was extracted with dichloromethane and the
combined organic phases were washed with water. Removal of the
dried (MgSO4) solvent gave a dark brown oil, which upon repeated
extractions with hot heptane, afforded the product as an off-white
solid (1.02 g, 90%), mp 126e129 ꢂC. 1H NMR (250 MHz, CDCl3):
d
2.69 (s, 3H, CH3), 3.78e3.76 (m, 8H, 50-CH2, 60-CH2, 80-CH2, 90-
CH2), 3.96e4.06 (m, 4H, 30-CH2, 110-CH2), 4.22e4.32 (m, 4H, 20-CH2,
120-CH2), 7.11 (s, 1H, 190-H), 7.20 (s, 1H, 140-H), 7.70 (d, J¼8.6 Hz, 1H,
180-H), 7.89 (dd, J¼8.6 and 1.5 Hz, 1H, 170-H), 8.31 (s, 1H, 150-H). 13C
NMR (250 MHz, CDCl3):
d 26.67, 68.50, 68.60, 69.32, 69.39, 70.37,
70.40, 71.41, 107.40, 109.15, 122.79, 126.72, 128.41, 128.60, 132.27,
133.14, 149.95, 151.48, 198.16. Anal. Calcd for C20H24O6: C, 66.65; H,
6.71. Found: C, 66.37; H, 6.68.
4.3. Typical procedure for BayereVilliger oxidation
An adaptation of the previously reported procedures9,10a was
used. m-Chloroperbenzoic acid (70%, 3 mmol) was added to
a stirred solution of ketone 10 (1.5 mmol), TsOH (1 mmol) in
dichloromethane (10 ml) in a single portion. The mixture was
stirred at room temperature overnight under argon atmosphere,
then filtered and the precipitate formed was washed with
dichloromethane. The organic phase was washed with 10% aque-
ous sodium bisulfite solution (2ꢃ20 ml), a saturated aqueous
NaHCO3 solution (3ꢃ20 ml), brine (2ꢃ20 ml) then dried (MgSO4)
and evaporated.
Fig. 7. Thermal bleaching of naphthopyran 3 in acetonitrile solution (C3¼1.2ꢃ10ꢁ4 M,
cuvette 1 cm): (a) changes in the UV spectra, curve 1 corresponds to a spectrum after
20 s irradiation at 313 nm, curves 2e6 correspond to 1, 3, 5, 8, and 15 s after cessation
of irradiation, curve 7 corresponds to the chromene’s spectrum prior to irradiation; (b)
kinetic curve of the thermal relaxation monitored at 425 nm.
were determined in capillary tubes and are uncorrected. NMR
spectra were recorded on a Bruker Avance 250 MHz instrument
4.3.1. 2,3,5,6,8,9,11,12-Octahydronaphtho[2,3-b][1,4,7,10,13]pentaox-
acyclopentadecine-16-yl acetate (12). From ketone 10 (0.54 g,
1.5 mmol) as viscous oil sufficiently pure for subsequent use (ca.
0.23 g, 40%), analytical sample was recrystallized from MeOH as
colorless crystals, mp 133e134 ꢂC. 1H NMR (250 MHz, CDCl3):
for solutions in CDCl3 unless otherwise stated;
d values are given
in parts per million, coupling constants are quoted in hertz.
Melting points were not corrected. All chemicals were purchased
from Aldrich, Acros or AlfaAesar and used without additional
purification.
d
2.33 (s, 3H, CH3), 3.76e3.80 (m, 8H, 50-CH2, 60-CH2, 80-CH2,
90-CH2), 3.94e4.00 (m, 4H, 30-CH2, 110-CH2), 4.20e4.25 (m, 4H,
1
Fig. 8. H NMR spectra of 3 irradiated at 313 nm (ꢁ40 ꢂC, CD3CN, C3¼0.001 M).

S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
7881
4.4. 2,3,5,6,8,9,11,12-Octahydronaphtho[2,3-b][1,4,7,10,13]pen-
taoxacyclopentadecine-16-ol (6)
Ester 12 (0.23 g, 0.6 mmol) was suspended in water (40 ml) and
a solution of NaOH in water (30%, 20 ml) was added. The mixture
was stirred at ca. 50 ꢂC for 3 h and then cooled to room temperature.
The cooled solution was extracted with dichloromethane before
acidifying the aqueous layer to pH w2 using concd HCl followed by
repeated extraction with dichloromethane. The combined organic
phases were washed with water to pH w7, dried (MgSO4), and
evaporated. The residue was treated with pentane to give 6 as pale
brown solid (0.12 g, 60%). An analytical sample was recrystallized
from dichloromethane as colorless crystals, mp 157e158 ꢂC.1H NMR
(250 MHz, CDCl3): d 3.70e4.20 (m, 16H, crown-CH2), 6.74 (s, 1H, 15-
H), 6.90 (dd, J¼8.7 and 2.3 Hz,1H,17-H), 6.94e7.00 (m, 2H,14-H,19-
H), 7.39 (d, J¼8.7 Hz, 1H, 18-H). 13C NMR (250 MHz, CDCl3):
d 68.01,
68.41, 69.37, 69.50, 70.32, 70.36, 71.03,106.61,108.41,108.88,115.76,
123.99, 127.89, 130.60, 147.17, 149.66, 152.87. Anal. Calcd for
C18H22O6: C, 64.66; H, 6.63. Found: C, 63.65; H, 6.55.
Fig. 9. Effect of metal cations on the bleaching rate constant (k) of naphthopyran 3 in
acetonitrile at 299 K (C3¼6.7ꢃ10ꢁ5 M, cuvette 1 cm,
¼425 nm).
l
4.5. Typical procedures for chromene preparation
Procedure A. A modification of the previously reported pro-
cedure11 was used. The crowned phenol (or naphthol) (1 equiv),1,1-
diphenylprop-2-yn-1-ol (1 equiv), and TsOH (0.01 equiv) were
dissolved in toluene (10 ml) and stirred at ca. 70e80 ꢂC for 3e4 h.
On completion of the stirring the solvent was evaporated and the
product was eluted from silica (the eluents noted below allowed
Rf¼0.3e0.5).
20-CH2, 120-CH2), 7.02e7.10 (m, 3H, 140-H, 180-H, 190-H), 7.36 (s, 1H,
150-H), 7.65 (d, 1H, J¼8.8 Hz, 170-H). 13C NMR (250 MHz, CDCl3):
d
21.30, 68.40, 68.48, 69.33, 69.37, 70.33, 71.29, 107.59, 107.91,
117.33, 118.98, 127.34, 127.72, 129.73, 147.27, 149.15, 149.92, 169.93.
Anal. Calcd for C20H24O7$H2O: C, 60.90; H, 6.64. Found: C, 60.96;
H, 6.20.
Procedure B. An adaptation of the previously reported proce-
dure12c was used. A solution of titanium(IV) ethoxide (1.5 equiv) in
toluene (2 ml) was added to a stirred solution of the crowned
4.3.2. 14,19-Dioxo-2,3,5,6,8,9,11,12,14,19-decahydronaphtho[2,3-b]
[1,4,7,10,13]pentaoxacyclopentadecin-16-yl acetate (13). From ke-
tone 10 (0.84 g, 2.3 mmol) after eluting with 50% ethyl acetate/
cyclohexane as deep yellow solid (0.03 g, 3%), mp 122e125 ꢂC.
phenol (or naphthol) (1 equiv) and
b-phenylcinnamaldehyde
(1 equiv) in toluene (8 ml). The mixture was stirred at 100 ꢂC for
6 h under argon atmosphere and then cooled to ca. 40 ꢂC before
adding toluene (10 ml), water (1 ml), and silica (0.5 g). The mix-
ture was heated at 80 ꢂC for a further 30 min. The resulting
mixture was cooled to room temperature, then filtered and the
precipitate formed was washed with toluene. The organic layer
was separated, dried (MgSO4), and evaporated. The product was
eluted from silica.
1H NMR (250 MHz, CDCl3):
d 2.34 (s, 3H, CH3), 3.62e3.74 (m,
8H, 50-CH2, 60-CH2, 80-CH2, 90-CH2), 3.82e3.91 (m, 4H, 30-CH2,
110-CH2), 4.54e4.66 (m, 4H, 20-CH2, 120-CH2), 7.40 (dd, 1H, J¼8.4
and 2.3 Hz, 170-H), 7.74 (d, 1H, J¼2.3 Hz, 150-H), 8.07 (d, 1H,
J¼8.4 Hz, 180-H). 13C NMR (250 MHz, CDCl3):
d 21.16, 70.48,
70.52, 70.75, 70.77, 70.90, 70.96, 73.34, 73.37, 119.43, 126.84,
128.17, 128.43, 132.62, 147.22, 147.42, 155.00, 168.68, 181.19,
181.77. Anal. Calcd for C20H24
C, 57.01; H, 5.77.
O10$H2O: C, 56.60; H, 5.70. Found:
4.5.1. 18,18-Diphenyl-2,3,5,6,8,9,11,12-octahydro-18H-[1,4,7,10,13]
pentaoxacyclopentadeca[2,3-h]chromene (1a). Procedure A: From
Fig. 10. 1H NMR spectra of a solution of 3 alone and with Mg2þ at 1:1.5 ratio upon irradiation at 313 nm (ꢁ40 ꢂC, CD3CN, C3¼0.001 M).

7882
S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
Table 3
142.80, 144.83, 147.33, 150.14. Anal. Calcd for C31H34O7$2H2O: C,
67.13; H, 6.91. Found: C, 67.68; H, 6.96.
Crystal data and structure refinement parameters for 1a and 6
Compound
1a
6
4.5.5. 3,3-Diphenyl-9,10,12,13,15,16,18,19-octahydro-3H-[1,4,7,10,13]
CCDC
763,215
C29H30O6
316.35
763,216
C19H26Cl2O7
437.3
Colorless prism
0.30ꢃ0.30ꢃ0.15
293(2)
pentaoxacyclopentadeca[20,30:4,5]benzo[1,2-f]chromene
(3). Pro-
cedure A: From naphthol 6 (0.096 g, 0.29 mmol) after eluting from
silica using 10% methanol/dichloromethane as viscous oil
Empirical formula
Formula weight
Crystal color, habit
Crystal size (mm)
Temperature (K)
Crystal system
Space group
Colorless prism
0.23ꢃ0.20ꢃ0.15
100(2) K
Orthorhombic
Pbca
9.6763(19)
17.770(4)
27.452(6)
a
(0.024 g, 16%); procedure B: from naphthol 6 (0.2 g, 0.6 mmol) after
eluting from silica using 10% methanol/dichloromethane re-
crystallization from diethyl ether as pale beige solid (0.09 g, 29%),
Monoclinic
P21/n
mp 147e148 ꢂC. 1H NMR (250 MHz, CDCl3):
d 3.74e3.78 (m, 8H, 12-
ꢁ
a (A)
9.1000(2)
8.2070(2)
28.9379(9)
90.036(1)
2161.19(10)
4(1)
920
1.334
3.37
u
ꢁ
b (A)
CH2, 13-CH2, 15-CH2, 16-CH2), 3.87e3.95 (m, 4H, 10-CH2, 18-CH2),
4.10e4.22 (m, 4H, 9-CH2, 19-CH2), 6.24 (d, J¼9.9 Hz, 1H, 2-H), 6.96
(s, 1H, 21-H), 7.04 (d, J¼8.7 Hz, 1H, 5-H), 7.14e7.34 (m, 8H, AreH, 1-
H, 7-H), 7.41e7.51 (m, 5H, AreH, 6-H). 13C NMR (250 MHz, CDCl3):
ꢁ
c (A)
b
(ꢂ)
3
ꢁ
V (A )
Z(Z0)
4720.2(16)
8(1)
2016
1.335
0.93
F(000)
d
68.46, 68.48, 69.31, 70.24, 71.09, 82.17 (s, quat-C), 102.56, 109.17,
Dcalcd (g cmꢁ1
)
113.34, 116.15, 119.69, 124.88, 125.67, 126.97, 127.43, 127.54, 128.03,
128.11, 144.90, 147.36, 149.52, 149.96. Anal. Calcd for C33H32O6: C,
75.55; H, 6.15. Found: C, 75.23; H, 6.02.
Linear absorption,
Scan type
m
(cmꢁ1
)
u
q
Range (ꢂ)
1.48e29.27
6426 [Rint¼0.0741]
4246
1.41e28.24
4994 [0.071]
2468
Independent reflections
Observed reflections [I>2
Parameters
s
(I)]
4.6. X-ray crystallography
316
293
Final R(Fhkl): R1
wR2
GOF
0.0487
0.1219
1.015
0.387, ꢁ0.241
0.0786
0.3226
1.16
0.125; ꢁ0.406
Crystals suitable for X-ray diffraction were grown by slow
evaporation of solutions in CH2Cl2. X-ray diffraction experiments
ꢁꢁ3
Drmax
,
Drmin (e A
)
were carried out with a Bruker APEX II CCD area detector, using
ꢁ
graphite monochromated Mo K
a
radiation (
l
¼0.71073 A,
u-scans).
Reflection intensities were integrated using SAINT software and
absorption correction was applied semi-empirically using SADABS
program. The structures were solved by direct method and refined
by the full-matrix least-squares against F2 in anisotropic approxi-
mation for non-hydrogen atoms. Hydrogen atoms of the water
molecule were located from the Fourier density synthesis. In the
crystal of 6, the solvate CH2Cl2 molecule is disordered over three
positions with occupancies equal to 0.75, 0.15, and 0.15. Crystal data
and structure refinement parameters for 1a and 6 are given in Table
3. All calculations were performed using the SHELXTL software.
phenol 4a (0.57 g, 2 mmol) after eluting from silica with ethyl
acetate as a viscous oil (<0.01 g, <1%). See characteristics in lit.8
4.5.2. 21,21-Diphenyl-2,3,5,6,8,9,11,12,14,15-decahydro-21H-
[1, 4, 7,10,13,16]hexaoxacyclooctadeca[2, 3-h]chromene
(1b). Procedure A: From phenol 4b (0.33 g, 1 mmol) after eluting
from silica with ethyl acetate as a viscous oil (<0.01 g, <1%). See
characteristics in lit.8
4.5.3. 16,16-Diphenyl-2,3,5,6,8,9,11,12-octahydro-16H-[1,4,7,10,13]
pentaoxacyclopentadeca[2,3-g]chromene (2a). Procedure A: From
phenol 5a (0.03 g, 0.1 mmol) after eluting from silica with
15e50% benzene/ethyl acetate as a viscous oil (0.02 g, 4%); pro-
cedure B: from phenol 5a (0.57 g, 2 mmol) after eluting with 10%
methanol/dichloromethane as a pale orange powder (0.19 g,
4.7. Spectrokinetic measurements
UV absorption spectra were recorded using an Agilent HP-8453
spectrophotometer (Agilent Technologies) with the characteristic
time of recording ca. 2 s. High pressure mercury lamp with the set
of glass filters was used as a light source for stationary photolysis.
To measure rate constants of the dark reactions with the charac-
teristic time of several seconds, samples were irradiated in the
cuvette box of the spectrophotometer. The irradiation was per-
formed till the equilibrium between closed and open forms (pho-
tostationary state) was achieved. The achievement of
photostationary conditions was controlled by the absorption of the
open form in the visible spectral region. After that the irradiation
was interrupted and the kinetic curves corresponding to the re-
covery of the system to the initial closed state were recorded.
NMR spectra were recorded on a Bruker 500 spectrometer (1H,
500 MHz) equipped with TXI probe, using standard sequences.
Photoirradiation was carried out directly into the NMR tube in
a home-built apparatus with a 1000 W high-pressure HgeXe lamp
20%), mp 76e78 ꢂC. 1H NMR (300 MHz; CD3CN):
d 3.58e3.70 (m,
8H, 5-CH2, 6-CH2, 8-CH2, 9-CH2), 3.72e3.83 (m, 4H, 3-CH2, 11-
CH2), 3.96e4.02 (m, 2H, 2-CH2), 4.04e4.12 (m, 2H, 12-CH2),
6.25 (d, J¼9.8 Hz, 1H, 17-H), 6.48e6.63 (m, 2H, 18-H, 14-H), 6.69
(s, 1H, 19-H), 7.22e7.65 (m, 10H, AreH); 13C NMR (75 MHz,
CD3CN):
d 68.5, 68.8, 69.2, 69.7, 69.8, 70.1, 70.4, 70.5, 82.0 (s,
quat-C), 102.8, 112.9, 113.8, 123.3, 126.5, 126.8, 127.5, 128.2, 143.4,
145.3, 147.2, 150.4. Anal. Calcd for C29H30O6: C, 73.0; H, 6.4.
Found: C, 73.2; H, 6.3.
4.5.4. 19,19-Diphenyl-2,3,5,6,8,9,11,12,14,15-decahydro-19H-
[1,4,7,10,13,16]hexaoxacyclooctadeca[2,3-g]chromene (2b). Procedure
A: From phenol 5b (0.2 g, 0.6 mmol) after eluting from silica with
10% methanol/dichloromethane as a viscous oil (0.06 g, 19%); pro-
cedure B: from phenol 5b (0.33 g, 1 mmol) after eluting with 10%
methanol/dichloromethane as pale orange crystals (0.13 g, 25%),
equipped with a filter (Schott 11FG09: 259<
lmax¼330 nm, T¼79%) to select UV light and an interferential filter
¼313 nm).
l<388 nm with
(l
mp 72e74 ꢂC. 1H NMR (250 MHz, CDCl3):
d 3.58e3.72 (m, 12H, 5-
CH2, 6-CH2, 8-CH2, 9-CH2, 11-CH2, 12-CH2), 3.77e3.88 (m, 4H, 3-
CH2, 14-CH2), 3.96e4.08 (m, 4H, 2-CH2, 15-CH2), 5.94 (d, J¼9.7 Hz,
1H, 20-H), 6.39e6.52 (m, 3H, 17-H, 21-H, 22-H), 7.11e7.29 (m, 6H,
AreH), 7.30e7.38 (m, 4H, AreH). 13C NMR (250 MHz, CDCl3):
Acknowledgements
ꢀ
Financial support from Reseau Formation-Recherche Franco-
ꢂ
ꢀ
Russe du Ministere de l’Enseignement Superieur et de la Recherche
(MENESR), the Russian Foundation for Basic Research, Program of
Russian Academy of Sciences, and ARCUS program are greatly
d
68.56, 69.34, 69.63, 69.91, 70.53, 70.59, 70.66, 70.68, 82.43 (s,
quat-C), 102.61, 113.23, 113.38, 123.01, 126.35, 126.87, 127.34, 127.97,

S.V. Paramonov et al. / Tetrahedron 68 (2012) 7873e7883
7883
Chebun’kova, A.; Paramonov, S.; Fedorova, O.; Lokshin, V.; Samat, A. J. Phys. Org.
Chem. 2009, 22, 537e545; (c) Fedorova, O. A.; Strokach, Y. P.; Chebun’kova, A.
V.; Valova, T. M.; Gromov, S. P.; Alfimov, M. V.; Lokshin, V.; Samat, A. Russ. Chem.
Bull. 2006, 55, 287e294; (d) Ushakov, E. N.; Nazarov, V. B.; Fedorova, O. A.;
Gromov, S. P.; Chebun’kova, A. V.; Alfimov, M. V.; Barigelletti, F. J. Phys. Org.
Chem. 2003, 16, 306e309; (e) Fedorova, O. A.; Maurel, F.; Ushakov, E. N.; Naz-
arov, V. B.; Gromov, S. P.; Chebun’kova, A. V.; Feofanov, A. V.; Alaverdian, I. S.;
Alfimov, M. V.; Barigelletti, F. New J. Chem. 2003, 27, 1720e1730; (f) Kumar, A.;
Van Gemert, B.; Knowles, D. B. Mol. Cryst. Liq. Cryst. 2000, 334, 217e222.
8. Paramonov, S. V.; Fedorova, O. A.; Perevalov, V. P.; Lokshin, V.; Khodorkovsky, V.
Russ. Chem. Bull. 2008, 57, 2381e2384.
appreciated. The NMR facilities were funded by the Region Nord-
Pas de Calais (France), the Ministere de la Jeunesse de l’Education
Nationale et de la Recherche (MJENR), and the Fonds Europeens de
Developpement Regional (FEDER). Part of this collaborative work
was realized within the framework GDRI CNRS 93 ‘Phenics’ (Pho-
toswitchable Organic Molecular Systems & Devices).
Supplementary data
9. Wada, F.; Arata, R.; Goto, T.; Kikukawa, K.; Matsuda, T. Bull. Chem. Soc. Jpn. 1980,
53, 2061e2963.
10. (a) Godfrey, I. M.; Sargent, M. V.; Elix, J. A. J. Chem. Soc., Perkin Trans. 1 1974,
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1993, 36, 3015e3020.
Supplementary data related to this article can be found online at
http://dx.doi.org/10.1016/j.tet.2012.07.029.
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