5-Nitrogenated-naphthopyrans: Toward photoinduced hydrogen-bonded complexes

Article abstract of DOI:10.1002/poc.1218

A series of 3,3-diphenyl-3H-naphtho[2,1-b]pyrans substituted on 5-position by various nitrogenated functional groups has been synthesized. The photochromic reaction between the pyranic closed form and their open forms has been studied using NMR and UV-Vis

Full text of DOI:10.1002/poc.1218

JOURNAL OF PHYSICAL ORGANIC CHEMISTRY
J. Phys. Org. Chem. 2007; 20: 872–877
Published online 27 July 2007 in Wiley InterScience
(www.interscience.wiley.com) DOI: 10.1002/poc.1218
5-Nitrogenated-naphthopyrans: toward photoinduced
hydrogen-bonded complexes
1
2
2
1
*
´
Xavier Sallenave, Stephanie Delbaere, Gaston Vermeersch and Jean-Luc Pozzo
1
´
Institut des Sciences Moleculaires, University Bordeaux1, UMR CNRS 5255, F-33405 Talence, France
2
´
Laboratoire de Physique, Faculte de Pharmacie, University Lille 2, UMR CNRS 8009, F-59006 Lille, France
Received 4 January 2007; revised 8 March 2007; accepted 16 April 2007
ABSTRACT: A series of 3,3-diphenyl-3H-naphtho[2,1-b]pyrans substituted on 5-position by various nitrogenated
functional groups has been synthesized. The photochromic reaction between the pyranic closed form and their open
forms has been studied using NMR and UV–Vis spectroscopies. The ability of the photoinduced carbonyl group to
promote the formation of hydrogen-bonded complexes has been compared within the series. Copyright # 2007 John
Wiley & Sons, Ltd.
Supplementary electronic material for this paper is available in Wiley InterScience at http://www.mrw.interscience.
wiley.com/suppmat/0894-3230/suppmat/
KEYWORDS: photochromism; H-Bond; NMR; supramolecular chemistry
INTRODUCTION
properties of 3,3-diphenylnaphtho[2,1-b]pyrans1 and this
position is also a geometrical prerequisite for promoting
host–guest interaction involving the photoinduced car-
bonyl group. Furthermore compounds incorporating a
carbonyl group like ester or ketone have been
recently reported to lead to the formation of simple
and efficient photoswitchable system based on an enhan-
ced proportion of stable TT-isomer5 which remains
unusual within 3,3-diphenylnaphtho[2,1-b]pyrans and
2,2-diphenylnaphtho[1,2-b]pyrans.6 On another hand,
ureido derivatives have also been shown to preferentially
promote supramolecular recognition event through H-
bonding under UV irradiation.7 A better understanding of
these peculiar and promising effects is expected through
a structure-property relationship. The comparison of the
spectrokinetic properties of the target molecules will also
determine the more appropriate structural prerequisite.
Naphthopyrans constitute a class of photochromic com-
pounds which have been mainly studied for applications
as pigments in the ophthalmic industry for over 20 years.1
UV-irradiation leads to the Csp3—O bond cleavage pro-
ducing colored isomers, namely photomero-forms. This
phenomenon is more often thermally reversible, although
it can also be photochemically induced, giving rise to
applications in supramolecular chemistry. This electro-
cyclization process is unique in terms of the accompaning
large changes in the structural and electronic character-
istics. Consequently, different spirobenzopyran or related
naphthopyran derivatives containing ion responsive mole-
cules such as crown ether,2 amid group,3 or calixarenes4
have been synthesized and studied to determine the in-
fluence of the irradiation upon the complexation.
Photochromic molecules as bistable compounds are sui-
table for mimicking biological signal transduction
processes, and therefore, by combining molecular reco-
gnition with photochromic chemistry, conceptually new
photoresponsive systems will be created. With that in
mind, we aim to prepare and fully characterize suitable
5-amino substituted naphthopyrans that could develop
some H-bond network upon irradiation. Electron donor or
withdrawal substituents located on the C-5 position
significantly affect the well-documented photochromic
RESULTS AND DISCUSSION
The synthesis of target molecules with various donor and
acceptor hydrogen-bond sites requires the preparation
of a common key molecule: 5-amino-3,3-diphenyl-
[3H]naphtho[2,1-b]pyran (4a) (Scheme 1). This com-
pound was synthesized in three steps from the commer-
cially available 3-amino-2-naphthol (1). The first step
consists of the protection of the amino function in
presence of trifluoroacetic anhydride8 to afford (2). This
reduces the basic character of the nitrogen atom of
naphthol (2) and allows its chromenization using acid
´
*Correspondence to: J.-L. Pozzo, Institut des Sciences Moleculaires,
University Bordeaux1, UMR CNRS 5255, F-33405 Talence, France.
E-mail: jl.pozzo@ism.u-bordeaux1.fr
Copyright # 2007 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2007; 20: 872–877

PHOTOINDUCED HYDROGEN-BONDED COMPLEXES
873
OH
OH
(i)
The target molecules are obtained in one step from (4a)
or (4b) intermediates (Scheme 2). The reaction with
the n-octyl-isocyanate leads to the formation of urea
derivatives12 (5a) and (5b). Reaction with 1-bromooctan-
2-one13 affords respectively (6a) and (6b) according
to SN2 substitution. Compounds (7a) and (7b) are obtai-
ned by reacting respectively 5-aminochromenes (4a) or
(4b) with cyanuric acid14 and diisopropylamine as base
at room temperature, these conditions allow the control
of the monosubstitution of the triazine unit. All the
described compounds 5a–7b with two hydrogen-bonding
groups gave satisfactory elemental analysis and spectro-
scopic data.
H
NH2
N
(1)
(2)
O
CF3
X
X
(ii)
O
O
(iii)
X
X
H
NH2
N
O
CF3
(4a) X = H
(4b) X = F
(3a) X = H
(3b) X = F
The photochromic behavior of target molecules and
key amino intermediates has been determined under
continuous irradiation at room temperature using toluene
as solvent (see Experimental section for details). Three
main spectrokinetic parameters: (1) absorption maxima
of the colored form (lmax OF), (2) thermal bleaching rate
(kD), and (3) absorbance at the photostationnary state
(Apss) measured upon continuous irradiation have been
quantified for all non-fluorinated compounds and are
collected in Table 1. Previous studies have shown that the
fluorine atoms located on the phenyl groups do not affect
the spectrokinetic data inducing very tiny changes.15 The
presence of nitrogenated group directly linked on the
5-position of the 3,3-diphenyl-[3H]naphtho[2,1-b]pyran
does not suppress the photochromic behavior. Indeed Apss
values indicate a good response to irradiation even if
Scheme 1. Reagents and conditions: (i) (CF3CO)2O, THF,
658C; (ii) 1,1-diphenylprop-2-yn-1-ol or 1,1-(4,40- difluorophe
nyl)prop-2-yn-1-ol, p-toluenesulfonic acid (cat), toluene, reflux;
(iii) K2CO3, MeOH, H2O, reflux
catalysis9 with 1,1-diphenylprop-2-yn-1-ol.10 The pro-
tective group is then removed by treatment with K2CO3
in refluxing methanol/water mixture11 to afford (4a).
A similar synthetic pathway is used to prepare the
difluorinated corresponding compound (4b). This latter
product was obtained in lower yield in comparison with
(4a) due to the purification process.
X
slightly lowered with respect to parent molecule (Apss
¼
1.12).15 Comparison with unsubstitued parent chromene
also reveals a bathochromic effect on the maximum
absorption for the colored open forms, this one shifting
from 425 to 439–455 nm. More interestingly, the
photogenerated forms are more stable even at room
temperature as indicated by a significant decrease of
thermal bleaching constant rates. Some of us have
previously demonstrated that NMR spectroscopy is a
powerful technique to investigate the photochromic
behavior of chromenes.16 19F NMR is especially suitable
to distinguish between the various open form isomers and
to follow all the kinetic pathways. The evolution of
1H and 19F NMR spectra corresponding to the five
naphthopyrans difluorinated on the 4-position of phenyl
groups 3b–7b has been monitored at 243K in toluene
O
N
X
H
N
(5a) X = H
(5b) X = F
H
O
C8H17
X
(i)
O
N
X
(ii)
(4a) or (4b)
H
(6a) X = H
(6b) X = F
O
C6H13
X
(iii)
Table 1. Spectrokinetic data obtained for non-fluorinated
naphthopyransa
lmax
CF (nm)
lmax
OF (nm)
O
N
X
Compounds
Aeq
298kD (sꢀ1
)
H
(7a) X = H
(7b) X = F
3a
4a
5a
6a
7a
329
336
337
335
333
455
439
438
425
454
0.58
0.86
0.64
0.77
0.84
0.017
0.007
0.015
0.021
0.028
N
N
Cl
N
Cl
Scheme 2. Reagents and conditions: (i) n-octylisocyan-
ate, CH2Cl2, 25 8C; (ii) 1-bromooctan-2-one, THF, 25 8C;
(iii) cyanuric acid, N,N-diisopropylethylamine, THF, 25 8C
a 5 ꢁ 10ꢀ5 M solutions in toluene.
Copyright # 2007 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2007; 20: 872–877
DOI: 10.1002/poc

874
X. SALLENAVE ET AL.
Figure 1. 1H NMR spectra (a) before and (b) after irradiation
of 7b at 243 K, (c) 19F NMR spectrum after irradiation
solution. Those corresponding to compound 7b are depi-
1
cted in Fig. 1. Comparison of H NMR spectra before
Figure 2. Time evolution concentrations of 7b at 243 K
after irradiation
and just after irradiation indicates the decrease of signals
belonging to the initial closed form (7b) and the
appearance of new resonances with different peak-
intensities. These observations are more evident in the
19F NMR spectrum, where two pairs of signals are
detected after irradiation characterizing the presence of
both expected transoid photomerocyanines, TC and TT.
The more concentrated photomerocyanine is identified as
TC isomer due to the more deshielded doublet signal at
9.2 ppm, characterizing proton H-2 with a coupling
constant of 12.4 Hz.14 The thermal relaxation of irradiated
solutions has been followed by recording NMR spectra
at regular time-intervals for several hours after the
irradiation was stopped. The measurement of peak-
intensities makes it possible to plot time evolution of their
concentrations (Fig. 2). The major concentrated isomer
TC follows a mono-exponential decay while the second
isomer, TT, presents no significant thermal evolution at
243 K. Similar behaviors have been observed for each of
the five investigated molecules, and the calculated rate
constants of bleaching, 243kD TC ! CF are reported in
Table 2. In contrast, 19F NMR chemical shift changes and
broadening of one signal in TC isomer are restricted to
compound (5b) which possesses a urea group inducing a
self-association process as previously reported.7 Repla-
cement of this group by amino-b-carbonylated (6b) or
aminotriazine units (7b) totally suppress self-assembling.
This has been also observed for intermediates (3b,4b).
This opens new prospect in designing 2H-chromenes that
could act as receptor through multiple hydrogen-bond
complementarity which will be revealed only for the
colored forms. These selected side arms could promote an
ADA system (Fig. 3). The aminotriazine unit which has
extensively used in supramolecular chemistry17 appears
particularly attractive as a second substitution is easily
achieved so numerous structural variations are reachable
including systems with quadruple hydrogen-bond. Prep-
aration of such compounds and characterization of
selective association under irradiation are under progress.
CONCLUSION
We have demonstrated that simple 5-aminosusbtituted
3,3-diphenyl-naphtho[2,1-b]pyrans are excellent photo-
chromic compounds. Conveniently substituted 5-nitro-
genated naphthopyrans appear to be promising building
blocks for supramolecular purpose through the use of
their photoinduced carbonyl group as hydrogen-bonding
acceptor group as self-assembly through hydrogen-bond
of their corresponding open forms is restricted to ureido
derivatives. This approach constitutes a new route toward
nanosized architecture which could be reversibly influ-
enced upon irradiation.
EXPERIMENTAL
Photochromic measurements (UV–Vis) were performed
in toluene solution (5 ꢁ 10ꢀ5 M) of spectrometric grade
(Aldrich) at 20 8C. The analysis cell (optical pathlength
1 cm) was placed in a thermostated copper block
with magnetic stirring inside the sample chamber of a
Copyright # 2007 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2007; 20: 872–877
DOI: 10.1002/poc

PHOTOINDUCED HYDROGEN-BONDED COMPLEXES
875
Table 2. Rate constants of bleaching and ratio obtained
after 10 min of UV irradiation determined by NMR spec-
troscopy
(1H, d, J 7.6 Hz, H-8), 7.85 (1H, t, J 7.6 Hz, H-5), 8.13
(1H, s, H-4), 10.5–10.72 (2H, br, NH and OH); dC
(62.5 MHz, DMSO-d6): 150.7, 140.9, 134.1, 128.8, 128.3,
127.6, 127.0, 125.7, 125.2, 124.8, 119.5, 110.9.
Compounds
243kD (sꢀ1
)
TC/TT/CF
ꢀ5
ꢀ5
ꢀ5
ꢀ5
4b
5b
6b
7b
3.22 ꢁ 10
3.46 ꢁ 10
1.16 ꢁ 10
18.0 ꢁ 10
74/21/5
79/13/8
73/13/14
80/6/14
5-trifluoroacetamido-3,3-diphenylnaphto[2,1-
b]pyrane (3a). A mixture of 1,1,1-N-2(30-hydroxynaphtyl)
ethanamide (2) (820mg, 3.21mmol), 1,1-diphenylpropyn-
1-ol (672 mg, 3.24 mmol), and APTS (80 mg, 0.42 mmol)
is dissolved in toluene (40 mL) and refluxed for 10 h. The
solvent removed, the crude product was purified by
flash column chromatography using CH2Cl2/petroleum
Ph
Ph
Ph
Ph
´
ether (1:1) as eluent [comme eluant un melange ether de
petrole/CH2Cl2 (1:1)]. The solid is then washed with
´
´
O
hν
O
´
H
N
pentane to afford 3 as a white solid. Yield 830 mg (58%);
mp 207–208 8C; dH (250 MHz, DMSO-d6): 6.27 (1H, d,
J 10 Hz, H-2), 7.31–7.55 (13H, H-8,9,1,20,30,40), 7.78
(1H, d, J 8.6 Hz, H-7), 7.94 (1H, d, J 8.6 Hz, H-10), 8.69
(1H, s, H-6), 8.87 (1H, s, NH); dC (62.5 MHz, DMSO-d6):
129.2, 128.9, 128.6, 128.5, 127.2, 127.0, 125.4, 121.5,
119.6, 118.8; MS (FAB) m/z 446 (MHþ), 368 (M-C6H5).
H
X
N
X
Closed Form (CF)
Open Form (OF)
Figure 3. Photochromic process. This figure is available in
colour online at www.interscience.wiley.com/journal/poc
Beckman-DU-7500-diode-array spectrometer. An Oriel
150 W high pressure Xe lamp was used for irradiation.
For NMR investigations, samples (2 ꢁ 10ꢀ3 M in
toluene-d8) were irradiated directly in the NMR tube
(5 mm), thermoregulated, using a 1000 W Xe–Hg HP
filtered short-arc lamp (Oriel) equipped with filter for UV
irradiation (Schott 011FG09, 259<l<388 nm). After
irradiation, the sample was transferred into the thermo-
regulated probe of a Bruker Avance-DPX or AC-300P
NMR spectrometer (1H, 300 MHz, 19F, 282 MHz).
Flash column chromatography was performed on silica
gel (Merck 40–63 mm). Melting point was determined by
a melting point apparatus from Electrothermal Eng. Ltd
5-trifluoroacetamido-3,3-di-(4(-fluorophenyl)na-
phto[2,1-b]pyrane (3b). A mixture of 1,1,1-N-2(30-
hydroxynaphtyl)ethanamide (2) (350 mg, 1.37 mmol),
1,1-di-40fluorophenylpropyn-1-ol (325 mg, 1.37 mmol),
and APTS (60 mg, 0.315 mmol) is dissolved in toluene
(20 mL) and refluxed for 14 h. The solvent removed, the
crude product was purified by flash column chromatog-
raphy using CH2Cl2/hexane (1:3) as eluent. Yield 315 mg
(48%); mp 203 8C; dH (250 MHz, DMSO-d6): 6.27 (1H, d,
J 10 Hz, H-2), 7.31–7.55 (13H, H-8,9,1,20,30,40), 7.78
(1H, d, J 8.6 Hz, H-7), 7.94 (1H, d, J 8.6 Hz, H-10), 8.69
(1H, s, H-6), 8.87 (1H, s, NH); dC (62.5 MHz, DMSO-d6):
164.6, 160.7, 145.8, 141.7, 129.9, 129.6, 129.4, 129.3,
128.7, 127.8, 126.1, 124.8, 123.1, 121.1, 116.6, 116.4,
116.2, 82.8; dF (toluene-d8): -112.9; MS (FAB) m/z 482
(MHþ), 385 (M-C6H4F).
1
and was uncorrected. H and 13C NMR spectra were
determined on a Bruker AC 250 NMR spectrometer with
CDCl3 or DMSO-d6 as solvent and TMS as internal
standard (d ¼ 0 ppm). 19F NMR spectra were obtained on
a Bruker (DPX 300 or AC 300) NMR spectrometer with
toluene-d8 as solvent. Mass spectra were recorded on a
VG AutoSpec apparatus using electronic impact at 70 eV.
Microanalyses were carried out in the microanalytical
Laboratory at the CNRS, Vernaison.
5-amino-3,3-diphenylnaphto[2,1-b]pyrane
(4a). A mixture of 5-trifluoroacetamido-3,3-diphenyl-
naphto[2,1-b]pyrane (3a) (307 mg, 0.69 mmol) and
potassium carbonate (600 mg, 4.34 mmol) is dissolved
in a mixture of methanol (25 mL) and water (1.6 mL). The
reaction mixture is then refluxed for 2 h. The solvent
removed, the crude product was purified by flash
column chromatography using CH2Cl2/petroleum ether
(1:1) as eluent. The solid is then washed with pentane to
afford 3 as a white solid. Yield 830 mg (58%); mp 187 8C;
dH (250 MHz, DMSO-d6): 5.50 (2H, s, NH2), 6.57 (1H, d,
J 9.9 Hz, H-2), 6.85 (1H, s, H-6), 7.03–7.34 (8H, m, H-
8,9,30,40), 7.37 (1H, d, J 8.5 Hz, H-1), 7.41 (1H, d, J
7.6 Hz, H-7), 7.56 (4H, m, H-20), 7.82 (1H, d, J 7.8 Hz, H-
10); dC (62.5 MHz, DMSO-d6): 138.8, 131.4, 129.2,
128.7, 127.4, 125.2, 123.2, 122.5, 121.3, 109.4; MS
(FAB) m/z 350 (MHþ), 272 (M-C6H5).
Preparation of compounds
1,3,3-trifluoro-N-2-(3(hydroxynaphthyl)ethana-
mide (2). A mixture of 3-amino-2-naphtol (1 g,
6.28 mmol) and trifluoroacetic anhydride (1.35 g,
6.66 mmol) is dissolved in THF (40 mL) and stirred for
1 h at 65 8C. The solvent removed, the crude product was
washed with water and dried. Recrystallization in ethanol
affords title compound 2. Yield 870 mg (54%); mp
243 8C; dH (250 MHz, DMSO-d6): 7.3 (1H, s, H-1), 7.35
(1H, t, J 7.6 Hz, H-6), 7.48 (1H, t, J 7.6 Hz, H-7), 7.72
Copyright # 2007 John Wiley & Sons, Ltd.
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DOI: 10.1002/poc

876
X. SALLENAVE ET AL.
5-amino-3,3-di-4(fluorophenylnaphto[2,1-b]pyr-
ane (4b). A mixture of 3b (300 mg, 0.62 mmol) and
potassium carbonate (520 mg, 3.76 mmol) is dissolved in
a mixture of methanol (25 mL) and water (1.6 mL). The
reaction mixture is then refluxed for 2 h. The solvent
removed, the crude product was purified by flash column
chromatography using CH2Cl2/petroleum ether (1:3) as
eluent. The solid is then washed with pentane to afford 3
as a white solid. Yield 195 mg (81%); mp 74 8C; dH
(250 MHz, DMSO-d6): 5.50 (2H, s, NH2), 6.58 (1H, d, J
10 Hz, H-2), 6.89 (1H, s, H-6), 7.08–7.24 (6H, m, H-
8,9,20), 7.38–7.49 (2H, m, H-1,7), 7.63 (4H, m, H-30),
7.86 (1H, d, J 8.2 Hz, H-10); dC (62.5 MHz, DMSO-d6):
164.6, 160.7, 142.2, 138.8, 131.5, 129.6, 128.9, 126.7,
125.3, 123.7, 123.2, 122.6, 121.6, 116.4, 115.9, 115.1,
109.4, 82.2; dF (toluene-d8): -113.3; MS (FAB) m/z 386
(MHþ), 289 (M-C6H4F).
in THF (10 mL) was stirred at room temperature for 24 h.
The solvent removed, the crude product was purified by
flash column chromatography using CH2Cl2/petroleum
ether (1:2) as eluent. Yield 0.100 g (43%); mp 146–
147 8C; dH (250 MHz, CDCl3): 0.88 (3H, t,
J
6.2 Hz, CH3), 1.31 (6H, m, C—CH2—C), 1.66 (2H,
qu, J 7.0 Hz, CO—C—CH2), 2.54 (2H, t, J 7.1 Hz,
CO—CH2), 4.09 (2H, d, J 6.3 Hz, N—CH2—CO), 5.58
(1H, t, J 6.5 Hz, NH), 6.27 (1H, d, J 10 Hz, H-2), 6.62 (1H,
s, H-6), 7.15–7.40 (10H, m, H-1,7,8,9, 30,40), 7.47 (4H, m,
H-20), 7.84 (1H, d, J 8.3 Hz, H-10); dC (62.5 MHz,
CDCl3): 155.1, 148.2, 145.1, 136.2, 129.3, 128.8, 128.1,
127.9, 127.2, 126.3, 124, 121.9, 120.1, 119.6, 105.4, 53.2,
41, 32.1, 28.8, 24.1, 23; MS (FAB) m/z 476 (MHþ), 398
(M-C6H5), 362 (ArNHCH2); Anal calc for C33H33NO2:
C, 83.33; H, 6.99; found: C, 83.48, H, 7.04.
1-(3,3-(4,4(-difluorophenyl)-[3H]naphtho[2,1-b]-
pyran-5-a-mino)-octan-2-one (6b). Starting with 4b
(0.150 g, 0.311 mmol), the same procedure as for 6a was
applied with 1-bromooctan-2-one (0.250 g, 1.20 mmol)
and stirring for 72 h. Yield 0.060 g (38%); mp 148 8C; dH
(250 MHz, DMSO-d6): 0.88 (3H, t, J 6.2 Hz, CH3), 1.42
(6H, m, C—CH2—C), 1.70 (2H, qu, J 7.3 Hz,
CO—C—CH2), 2.60 (2H, t, J 7.1 Hz, CO—CH2), 4.10
(2H, d, J 6.3 Hz, N—CH2—CO), 5.58 (1H, t, J 6.5 Hz,
NH), 6.27 (1H, d, J 10.1 Hz, H-2), 6.65 (1H, s, H-6),
6.93–7.12 (4H, m, H-20), 7.25–7.36 (3H, m, H-1,8,9),
7.39–7.55 (4H, m, H-30), 7.58 (1H, d, J 8.1 Hz, H-7), 7.88
(1H, d, J 8.2 Hz, H-10); dF (toluene-d8): -113.35; MS
(FAB) m/z 512 (MHþ), 415 (M-C6H4F), 398 (ArNHCH2);
Anal calc for C33H31F2NO2: C, 77.42; H, 6.11; found: C,
77.49, H, 6.12.
1-(3,3-diphenyl-[3H]naphtho[2,1-b]pyran)-3-oct-
ylurea (5a). To n-octylisocyanate (0.270 g, 1.74 mmol)
in CH2Cl2 (3 mL) was added dropwise a solution of 4a
(0.150 g, 0.43 mmol) in CH2Cl2 (8 mL). The mixture was
stirred at room temperature for 72 h. The solvent
removed, the crude product was purified by flash
column chromatography using CH2Cl2/petroleum ether
(1:2) as eluent. Yield 0.120 g (56%); mp 181–182 8C; dH
(250 MHz, DMSO-d6): 0.85 (3H, t, J 6 Hz, CH3), 1.38
(12H, m, C—CH2—C), 3.10 (2H, q, J 5.9 Hz, N—CH2),
6.50 (1H, d, J 9.9 Hz, H-2), 7.19–7.42 (8H, m, H-
8,9,30,40), 7.47 (1H, d, J 10.1 Hz, H-1), 7.54 (4H, m, H-20),
7.62 (1H, d, J 8.2 Hz, H-7), 7.97 (1H, d, J 8 Hz, H-10),
8.06 (1H, s, NH), 8.52 (1H, s, NH); dC (62.5 MHz,
DMSO-d6): 156.4, 145.6, 141.4, 130.4, 130.3, 130, 129.4,
128.9, 128.7, 127.9, 125.7, 125.5, 122.6, 120.8, 116.1,
115.1, 84.1, 32.6, 31, 30.1, 30, 27.8, 23.4, 15.3; MS
(FAB) m/z 505 (MHþ), 427 (M-C6H5); Anal calc
for C34H36N2O2: C, 80.92; H, 7.19; found: C, 81.02,
H, 7.21.
2,4-dichloro-6-(3,3-diphenyl-[3H]naphtho[2,1-b]-
pyran-5-a-mino)-1,3,5-triazine (7a). A solution of
cyanuric acid (0.084 g, 0.455 mmol) and THF (5 mL)
under nitrogen was stirred at 0 8C. 4a (0.150 g,
0.430 mmol) in THF (5 mL) was added dropwise
and N,N-diisopropylethylamine (0.056 g, 0.434 mmol)
was then added to the solution. The mixture was
stirred at 25 8C for 2 h. The solvent evaporated, the
crude product was purified by flash column chromatog-
raphy using CH2Cl2/petroleum ether (2:3) as eluent.
Yield 0.130 g (61%); mp 250–252 8C; dH (250 MHz,
DMSO-d6): 6.62 (1H, d, J 10 Hz, H-2), 7.17–7.35 (6H, m,
H-30,40), 7.36–7.48 (5H, m, H-1,20), 7.49–7.61 (2H, m,
H-8,9), 7.86 (1H, s, H-6), 7.93 (1H, d, J 8.5 Hz, H-7), 8.14
(1H, d, J 8.5 Hz, H-10), 11.11 (1H, s, NH); MS (LSIMS)
m/z 498.4 (MHþ); Anal calc for C28H18Cl2N4O: C, 67.61;
H, 3.65; found: C, 67.75, H, 3.59.
1-(3,3-(4,4(-difluorophenyl)-[3H]naphtho[2,1-b]-
pyran)-3-octylurea (5b). Starting with 4b (0.180 g,
0.467 mmol), the same procedure as for 5a was applied
with n-octylisocyanate (0.270 g, 1.74 mmol). Yield
0.106 g (42%); mp 185 8C; dH (250 MHz, DMSO-d6):
0.85 (3H, t, J 6.2 Hz, CH3), 1.1–1.58 (12H, m,
C—CH2—C), 3.12 (2H, q, J 5.9 Hz, N—CH2), 6.47
(1H, d, J 10 Hz, H-2), 7.15–7.38 (7H, m, H-6,8,9, 20), 7.47
(1H, d, J 9.8 Hz, H-1), 7.52–7.62 (4H, m, H-30), 7.63 (1H,
d, J 8.1 Hz, H-7), 7.98 (1H, d, J 8.3 Hz, H-10), 8.07 (1H, s,
NH), 8.53 (1H, s, NH); dF (toluene-d8): -112.75; MS
(FAB) m/z 541 (MHþ), 444 (M-C6H4F). Anal calc
for C34H34F2N2O2: C, 75.53; H, 6.34; found: C, 75.41, H,
6.23.
2,4-dichloro-6-(3,3-(4,4(-difluorophenyl)-[3H]na-
phtho[2,1-b]pyran-5-amino)-1,3,5-triazine
(7b). Starting with 4b (0.100 g, 0.260 mmol), the same
procedure as for 7a was applied with cyanuric acid
(0.052 g, 0.28 mmol). Yield 0.057 g (42%); mp 182 8C; dH
1-(3,3-diphenyl-[3H]naphtho[2,1-b]pyran-5-ami-
no)-octan-2-one (6a). A solution of 4a (0.170 g,
0.487 mmol) and 1-bromooctan-2-one (0.360 g, 1.74 mmol)
Copyright # 2007 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2007; 20: 872–877
DOI: 10.1002/poc

PHOTOINDUCED HYDROGEN-BONDED COMPLEXES
877
(250 MHz, DMSO-d6): 6.62 (1H, d, J 9.8 Hz, H-2),
7.08–7.28 (4H, m, H-20), 7.38–7.68 (7H, m, H-30,1,8,9),
7.88 (1H, d, J 8.5 Hz, H-7), 7.97 (1H, s, H-6), 8.19 (1H, d,
J 8.4 Hz, H-10), 11.31 (1H, s, NH); dF (toluene-d8):
-112.7; MS (LSIMS) m/z 534.4 (MHþ); Anal calc
for C28H16Cl2F2N4O: C, 63.05; H, 3.02; found: C, 62.97,
H, 3.00.
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The 300 MHz NMR facilities were funded by the Region
`
Nord-Pas-de-Calais, the Ministere de la Jeunesse, de
l’Education Nationale et de la Recherche, and FEDER.
This collaborative work was realized within the frame-
work CNRS GDR 2466. S. D. and J-L P. acknowledge
‘Phenics’ (Photoswitchable Organic Molecular Systems
& Devices) GDRI CNRS n 93 for financial support and
G. V. is indebted to the French Embassy in Japan, for the
financial support, during Japan-French Seminar in Japan.
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Copyright # 2007 John Wiley & Sons, Ltd.
J. Phys. Org. Chem. 2007; 20: 872–877
DOI: 10.1002/poc