Synthesis of heterocyclic chromenes via Buchwald C-N coupling and the substituent effect on their photochromic properties

Article abstract of DOI:10.1016/j.tet.2008.07.116

Synthesis of series of new heterocyclic [2]H- and [3]H-chromenes via Buchwald C-N coupling is described. Introduction of heterocyclic substituent to 6-position of benzopyrans and in 8-position of naphthopyrans led to significant bathochromic shift (up to

Full text of DOI:10.1016/j.tet.2008.07.116

Tetrahedron 64 (2008) 9977–9982
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Synthesis of heterocyclic chromenes via Buchwald C–N coupling and the
substituent effect on their photochromic properties
*
´
`
´
Ekaterina A. Shilova , Gerard Pepe, Andre Samat, Corinne Moustrou
Universite´ de la Me´diterrane´e, UMR CNRS 6114, Facult´e des Sciences de Luminy, case 901, 13288 Marseille cedex 09, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Synthesis of series of new heterocyclic [2]H- and [3]H-chromenes via Buchwald C–N coupling is de-
scribed. Introduction of heterocyclic substituent to 6-position of benzopyrans and in 8-position of
naphthopyrans led to significant bathochromic shift (up to 154 nm) in the spectra of their open forms.
Substituted benzopyrans display high colorability values along with acceptable resistance to fatigue. By
using judicious substituents, the absorption range of this type of pyrans can be tuned according to the
nature of the heterocyclic unit, and the photochromic properties of pyrans could be adjusted to desired
values.
Received 27 February 2008
Received in revised form 29 July 2008
Accepted 30 July 2008
Available online 8 August 2008
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
Chromenes are of special interest as photochromic compounds1
due to their photo-induced reversible electrocyclic opening of the
pyran ring (Scheme 1).
[2]H- and [3]H-Chromenes represent an important class of
molecules2,3 being the main subunits in numerous natural and
biologically active compounds. They are widely adopted for
fabrication of opto-electronic devices and ophthalmic lenses.4
Development of chromenes with programmed photochromic
properties is of foremost importance.
Scheme 1. Photo-induced reversible electrocyclic opening of the pyran ring.
The absorption of the merocyanine ring-opened form de-
pends strongly on the substituents.5 The incorporation of het-
erocyclic units into chromene molecules may lead to the
enhancement of its photochemical properties as well as to their
more extended application. This raises a possibility of synthesis
of chromenes with particular photochromic properties by the
introduction of various substituents. However, this approach
faces two problems. First, the dependence of the photochromic
properties of heterocyclic substituents has not been profoundly
investigated. Secondly, the repertoire of electron-donating sub-
stituents was limited due to the complexity of the synthetic
methods. This paper describes the important issue of chromene
researchdthe development of novel synthetic conditions en-
abling to introduce the electron-donating substituents to
chromenes.
2. Results and discussion
Recently, Buchwald developed powerful methodology6–9 for the
amination of aryl halides. Palladium-promoted cross-coupling
reactions have been widely applied for the functionalization of
variety of cyclic secondary amines. However, the reaction of
Buchwald has not been employed for electron-donating
substituents’ introduction to the chromene molecules. We have
previously employed this strategy for the synthesis of various
aminochromenes.10,11 Prompted by our studies dealing with the
palladium-catalyzed C–N coupling of bromopyrans we became
interested in determining whether a related process could be used
for the rapid buildup of diverse heterocyclic chromenes from
potentially simple starting materials. Starting from pyrans 1–412,13
containing the bromine-group available for modification (Scheme
2), we prepared a library of pyran-heterocyclic tandems using
morpholine, piperidine, pyrrolidine, and pyrrole.
The coupling was carried out in the presence of tris(dibenzi-
lideneacetone)dipalladium(0) (2 mol %), 2-(di-t-butylphosphino)-
biphenyl (4 mol %), aryl halide (0.9 equiv), amine (1 equiv),
* Corresponding author. Tel.: þ33 4 91 82 91 54; fax: þ33 4 91 82 93 01.
E-mail address: shilova@discoverylab.eu (E.A. Shilova).
0040-4020/$ – see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.07.116

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E.A. Shilova et al. / Tetrahedron 64 (2008) 9977–9982
sodium tertbutoxide (1.4 equiv) in refluxing toluene (1 mL/mmol)
under argon. In most cases chromene-bromides 1–4 were found
to be rather reactive under the general conditions (entries 4–6,
Table 1).
Good to excellent yields were observed for arylbromides cou-
pled with saturated heterocyclic amines (entries 1–12). Extension
of this chemistry to include pyrrole as substrate appeared to be less
successful. After a few tests, we noticed that better yields in this
case could be achieved when low temperature is applied (40 ꢀC)
(entries 13–15). Rise of reaction temperature to 80 ꢀC leads to rapid
disappearance of starting material (about 30 min) and to simulta-
neous increase in by-products formation.
The structure of one of the target compounds was determined
by X-ray crystallographic analysis14 (Fig. 1). Morpholine derivative
of 2 (entry 4) has unit cells that contain two crystallographically
independent, but virtually structurally identical molecules in
asymmetric crystal unit.
The electronic absorption spectra of the new naphthopyrans
and benzopyrans were monitored15 without and under UV irradi-
ation. Both series exhibit photochromic properties at room tem-
perature (Fig. 2).
Main absorption bands (in the region 300 nm to 700 nm) are
collected in Tables 2 and 3 (naphthopyrans) and Tables 4 and 5
(benzopyrans, demonstrated measurable levels of absorption
under given15 irradiation conditions). In each case the results
are compared to the unsubstituted parent compounds16,17
(Scheme 3).
Scheme 2. Synthesis of heterocyclic chromenes.
Table 1
Palladium-catalyzed coupling of chromenes with morpholine, piperidine and
pyrrolidine
As stated before,18 the introduction of N-containing heterocycle
at the C8 position of 3,3-diphenyl-3H-naphtho[2,1-b]pyrans led to
a global bathochromic shift in the spectra of the open forms (Table
2). As we expected, novel heterocyclic naphthopyrans exhibit an
Entry
ArBr
Amine
Yield, %
Time/h
1
2
3
4
5
6
7
8
1
1
1
2
2
2
3
3
3
4
4
4
1
2
3
Morpholine
Piperidine
Pyrrolidine
Morpholine
Piperidine
Pyrrolidine
Morpholine
Piperidine
Pyrrolidine
Morpholine
Piperidine
Pyrrolidine
Pyrrole
73
86
87
84
81
79
87
75
94
83
71
89
49a
33a
46a
24
20
40
24
4
1.5
20
24
40
20
36
64
49
2.5
4
imposing displacement of maximum-absorption wavelength (Dl2
)
at long wave region up to 120 nm (NP4) after irradiation by UV
light. An intensive band appears also in the UV region (344–
359 nm) showing a slight hypsochromic shift according to the na-
ture of the 8-substituent. It can be noticed that regarding to the
closed forms, the far UV absorption band is sensitive to this sub-
stitution, the higher shift being obtained also for NP4 (31 nm)
(Table 3).
Concerning the benzopyran series (Tables 4 and 5), it appears
that the open form of the parent compound (P1) compared to the
naphthopyran one (NP1), shows a bathochromic shift at the lmax
(482 nm instead 432 nm) but also the presence of a second band in
the near visible range (420 nm).
9
10
11
12
13
14
15
Pyrrole
Pyrrole
a
t¼40 ꢀC.
Figure 1. The molecular structure of the crystalline compound 4.

E.A. Shilova et al. / Tetrahedron 64 (2008) 9977–9982
9979
Table 4
Absorption properties of the open forms of benzopyrans
Entry
Structure
lmax, nm
Dl1
,
Dl2, nm
P1
420, 482
d, d
O
P2
P3
P4
336, 555
331, 567
336, 636
ꢁ84, 73
ꢁ89, 85
ꢁ84, 154
O
N
O
O
N
Figure 2. Absorption spectra of entry 9 under dark and irradiated conditions (aceto-
nitrile solutions, C¼0.84ꢂ10–5 M).
O
N
Table 2
Absorption properties of the open forms of naphthopyrans
Entry
Structure
lmax, nm
Dl1
(shift of lmax
, Dl2, nm
O
O
N
DMP2
DMP3
399, 527
397, 539
ꢁ21, 45
ꢁ23, 57
)
CH3
H3C
NP1
360, 432
d, d
O
O
N
CH3
H3C
O
N
N
NP2
344, 503
ꢁ16, 71
O
O
O
N
DMP4
413, 575
ꢁ7, 93
CH3
NP3
NP4
353, 524
359, 552
ꢁ7, 92
H3C
Table 5
N
Absorption properties of the closed forms of benzopyrans
ꢁ1, 120
O
Entry
lmax, nm
Dl
P1
P2
P3
P4
DMP2
DMP3
DMP4
320
344
341
318
327
330
336
d
24
21
ꢁ2
7
N
NP5
360, 462
0, 30
O
10
16
When the benzopyran ring is substituted by a nitrogenated
heterocycle in the 6-position (P2–P4), the lmax of the open form is
shifted to the red, the maximum being observed with a pyrrolidine
ring (þ154 nm). Curiously, at the same time, the UV range ab-
sorption band of this open form is shifted toward shorter wave-
lengths (about ꢁ70 nm).
unchanged. The benzopyran series seems to be very interesting
allowing higher bathochromic displacement than the naph-
thopyran one. For instance, in the pyrrolidine ring lmax is
552 nm for naphthopyran and 636 nm for benzopyran. More-
over, depending on the added substitutions, a wide covering of
the visible range (from 400 nm to 600 nm or moreover) can be
expected, which is interesting for the design of efficient photo-
chromic lenses.
Adding of two methyl groups in 7 and 8-positions seems to
minimize these effects, the higher shift of the lmax is þ93 nm
for DMP4, while the absorption in the UV range is quasi
Table 3
Absorption properties of the closed forms of naphthopyrans
Entry
lmax, nm
Dl
NP1
NP2
NP3
NP4
369
372
381
400
d
3
12
31
Scheme 3. Unsubstituted parent compounds.

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E.A. Shilova et al. / Tetrahedron 64 (2008) 9977–9982
4. Experimental
4.1. General
Glassware used in the reactions described below was dried for
a minimum of 12 h in an oven at 120 ꢀC. 1H NMR and 13C NMR
spectra were recorded on Bruker AC-250 at 250 MHz and 62.5 MHz,
respectively. Chemical shifts are reported in parts per million (d)
relative to the nondeuterated solvent peak. Coupling constants (J
values) are expressed in hertz (Hz), and spin multiplicities are in-
dicated by the following symbols: s (singlet), d (doublet), t (triplet),
q (quadruplet), m (multiplet). Silica TLC was conducted on pre-
coated aluminum sheets (60 F254) with a 0.2 mm thickness (Aldrich
Chemical Co.). Solvents and starting compounds were obtained
from commercial sources (Acros, Sigma and Aldrich). Photochem-
ical measurements were performed in acetonitrile solutions
(C¼0.84ꢂ10ꢁ5 M) of spectrometric grade at 20E. The analysis cell
was placed in sample chamber in Cary 50 Scan spectrophotometer.
Solutions were stirred continuously during experiments. An Oriel-
150-W-high-pressure Xe lamp was used for irradiation, 134 mW/
cm2. Mass spectrometry analyses were carried out on a 3200
QTRAP (Applied Biosystems SCIEX).
Figure 3. Absorption spectra of P1-P4 under irradiated conditions (toluene, 20 ꢀC,
C¼5ꢂ10–4 M).
Table 6
Resistance to fatigue (tA0/2) for benzopyrans P1–P4 (5ꢂ10ꢁ4 M in toluene, 20 ꢀC)
a
Entry
(tA0/2) min
f(tA0/2)
4.1.1. General procedure for the amination reactions
P1
P2
P3
P4
123.0
160.1
140.4
35.6
d
A Schlenk flask was charged with aryl halide (0.9 mmol), amine
(1 mmol), sodium tertbutoxide (1.4 mmol), tris(dibenzilideneace-
tone)dipalladium(0) (2 mol %), 2-(di-t-butylphosphino)biphenyl
(4 mol %) in toluene (1 mL/mmol) under argon. The flask was im-
mersed in an 80 EC oil bath with stirring until the starting material
had been completely consumed as judged by GC analysis. The so-
lution was allowed then to cool to room temperature, taken up in
ether and filtered. The solution was concentrated to dryness under
reduced pressure. The crude material was purified by column
chromatography with cyclohexane–acetone (90:10).
1.3
1.41
0.28
a
f(tA0/2)¼ratio pertaining to the resistance to fatigue with respect to the parent
compound P1.
The open forms of compounds P2–P4 show the high
corresponding colorability values (Fig. 3) comparing to parent
benzopyran P1. It is possible to conclude that the heterocyclic
constituent at 6-position of benzopyrans stabilizes the
photogenerated open forms.
The resistance to fatigue (photodegradation) of benzopyrans
P1–P4 under continuous UV irradiation was also evaluated (Table
6). We found that the values for the time required to reach 50% of
the initial value (tA0/2) for P2 and P3 is higher than one of the
parent compound P1. Unfortunately pyrrolidine substituted ben-
zopyran P4 displayed the decrease of its fatigue resistance (f(tA0/2
<1).
Compounds P2 and P3 show a good compromise between col-
orability and photodegradation, they could be useful in applications
relating to photochromic lenses.
4.1.1.1. 4-(3,3-Diphenyl-3H-benzo[f]chromen-8-yl)morpholine (1). 1H
NMR (250.13 MHz, CDCl3):
d
¼3.17 (t, J¼4.74 Hz, 4H), 3.86–3.90 (m,
4H), 6.24 (d, J¼9.96 Hz, 1H), 7.01 (d, J¼2.37 Hz, 1H), 7.13 (d,
J¼9.00 Hz, 1H), 7.16–7.21 (m, 3H), 7.26–7.32 (m, 5H), 7.44–7.52 (m,
5H), 7.85 (d, J¼9.16 Hz, 1H). 13C NMR (62.90 MHz, CDCl3):
¼50.12
d
(2ꢂCH2), 66.96 (2ꢂCH2), 82.32 (OC), 111.36 (CH]), 114.15 (C), 118.73
(CH]), 119.66 (CH]), 119.82 (CH]), 122.42 (CH]), 124.86 (C),
127.02 (4ꢂCH]), 127.48 (2ꢂCH]), 127.99 (CH]), 128.07 (4ꢂCH]),
128.62 (CH]), 130.25 (C), 144.90 (2ꢂC), 147.54 (C), 149.05 (C). HRMS
calcd for C29H25NO2 419.1885, found 419.1876. ESI-MS: m/z¼420
[MþH]þ.
)
4.1.1.2. 1-(3,3-Diphenyl-3H-benzo[f]chromen-8-yl)piperidine (2). 1H
NMR (250.13 MHz, CDCl3):
d
¼1.42–1.48 (m, 2H), 1.57–1.66 (m, 4H),
3. Conclusions
2.89–2.93 (m, 4H), 6.17 (d, J¼10.11 Hz, 1H), 6.62 (s, 1H), 6.75 (d,
J¼10.11 Hz, 1H), 7.11–7.24 (m, 6H), 7.35–7.36 (m, 4H). 13C NMR
Synthesis of new heterocyclic naphthopyrans and benzopyrans
by Buchwald palladium-catalyzed C–N coupling was efficiently
accomplished. Both series reveal photochromic properties at room
temperature in solution. Introduction of heterocyclic constituent to
6-position of benzopyrans and in 8-position of naphthopyrans
leads to global bathochromic shift in the spectra of their open
forms. Some of the substituted benzopyrans display high colo-
rability values along with good resistance to fatigue. These results
show that by using judicious substituents the absorption range of
this type of pyrans can be tuned according to the nature of the
heterocyclic constituent on the benzopyran subunit, and the pho-
tochromic properties could be adjusted to desired values. The
properties of this series of new chromenes open the new prospects
for their applications, they would be a good basis for elaboration of
opto-electronic devices and ophthalmic lenses.
(62.90 MHz, CDCl3):
d
¼24.24 (CH2), 25.85 (2ꢂCH2), 51.40 (2ꢂCH2),
82.20 (OC), 111.78 (CH]), 114.09 (C), 118.40 (CH]), 119.74 (CH]),
121.14 (CH]), 122.04 (CH]), 124.49 (C), 126.98 (4ꢂCH]), 127.39
(2ꢂCH]), 127.79 (C), 128.01 (4ꢂCH]), 128.52 (CH]), 130.35
(CH]),136.45 (C),144.93 (2ꢂC),148.78 (C). Mp¼178–179 ꢀC; HRMS
calcd for C30H27NO 417.2093, found 417.2081. ESI-MS: m/z¼418
[MþH]þ.
4.1.1.3. 1-(3,3-Diphenyl-3H-benzo[f]chromen-8-yl)pyrrolidine (3). 1H
NMR (250.13 MHz, CDCl3):
d
¼1.94–1.99 (m, 4H), 3.28 (br s, 4H),
6.17 (d, J¼9.95 Hz, 1H), 6.61 (s, 1H), 6.93 (d, J¼8.56 Hz, 1H), 7.03 (d,
J¼8.78 Hz, 1H), 7.12–7.25 (m, 7H), 7.39–7.43 (m, 5H), 7.75 (d, J¼9.14
Hz, 1H). 13C NMR (62.90 MHz, CDCl3):
d
¼25.43 (2ꢂCH2), 47.92
(2ꢂCH2), 82.10 (OC), 114.15 (CH]), 116.34 (CH]), 118.57 (CH]),
119.46 (C), 119.97 (CH]), 122.24 (CH]), 126.99 (CH]), 127.05

E.A. Shilova et al. / Tetrahedron 64 (2008) 9977–9982
9981
(4ꢂCH]), 127.37 (2ꢂCH]), 127.67 (CH]), 128.02 (4ꢂCH]),
128.16 (C), 131.03 (C), 144.60 (C), 145.12 (2ꢂC), 147.40 (C). HRMS
calcd for C29H25NO 403.1936, found 403.1927. ESI-MS: m/z¼404
[MþH]þ.
115.98 (CH]), 120.67 (C), 123.18 (CH]), 126.01 (4ꢂCH]), 126.23
(2ꢂCH]), 126.96 (4ꢂCH]), 128.70 (CH]), 142.20 (C), 142.30 (C),
144.14 (2ꢂC). HRMS calcd for C25H23NO 353.1780, found 353.1782.
ESI-MS: m/z¼354 [MþH]þ.
4.1.1.4. 4-(5,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)morpholine
4.1.1.10. 4-(7,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)morpholine
(4). 1H NMR (250.13 MHz, CDCl3):
d
¼2.24 (s, 3H), 2.26 (s, 3H), 2.75–
(10). 1H NMR (250.13 MHz, CDCl3):
d
¼2.14 (s, 3H), 2.19 (s, 3H),
2.79 (m, 4H), 3.78–3.82 (m, 4H), 6.17 (d, J¼9.96 Hz, 1H), 6.71 (s, 1H),
2.71–2.75 (m, 4H), 3.74–3.78 (m, 4H), 6.04 (d, J¼9.63 Hz, 1H), 6.53
6.82 (d, J¼10.11 Hz, 1H), 7.20–7.33 (m, 6H), 7.42–7.46 (m, 4H). 13
C
(d, J¼9.96 Hz, 1H), 6.55 (s, 1H), 7.18–7.28 (m, 6H), 7.37–7.41 (m, 4H).
NMR (62.90 MHz, CDCl3):
d
¼12.98 (CH3), 16.38 (CH3), 53.38
13C NMR (62.90 MHz, CDCl3):
d
¼12.37 (CH3), 14.24 (CH3), 52.97
(2ꢂCH2), 68.02 (2ꢂCH2), 81.76 (OC), 120.66 (C), 122.07 (CH]),
122.36 (CH]), 123.45 (C), 127.10 (C), 127.27 (4ꢂCH]), 127.73
(2ꢂCH]), 128.50 (4ꢂCH]), 129.10 (CH]), 144.91 (C), 146.00
(2ꢂC), 147.33 (C). Mp 129–130 ꢀC; HRMS calcd for C27H27NO2
397.2042, found 397.2037. ESI-MS: m/z¼398 [MþH]þ.
(2ꢂCH2), 67.54 (2ꢂCH2), 82.31 (OC), 114.81 (CH]), 118.43 (C),
124.01 (CH]), 125.24 (C), 126.85 (4ꢂCH]), 127.26 (2ꢂCH]),
127.86 (C), 128.05 (4ꢂCH]), 133.64 (CH]), 144.76 (C), 145.61
(2ꢂC), 146.58 (C). HRMS calcd for C27H27NO2 397.2042, found
397.2044. ESI-MS: m/z¼398 [MþH]þ.
4.1.1.5. 1-(5,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)piperidine
4.1.1.11. 1-(7,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)piperidine
(5). 1H NMR (250.13 MHz, CDCl3):
d
¼1.56–1.60 (m, 3ꢂCH2), 2.15 (s,
(11). 1H NMR (250.13 MHz, CDCl3):
d
¼1.47–1.55 (m, 6H), 2.04 (s,
3H), 2.18 (s, 3H), 2.61–2.62 (m, 4H), 6.17 (d, J¼10.11 Hz, 1H), 6.62 (s,
1H), 6.75 (d, J¼10.11 Hz, 1H), 7.11–7.24 (m, 6H), 7.35–7.36 (m, 4H).
3H), 2.10 (s, 3H), 2.56–2.57 (m, 4H), 5.94 (d, J¼9.64 Hz, 1H), 6.41–
6.45 (m, 2H), 7.09–7.20 (m, 6H), 7.29–7.33 (m, 4H). 13C NMR
13C NMR (62.90 MHz, CDCl3):
d
¼12.56 (CH3), 15.93 (CH3), 24.41
(62.90 MHz, CDCl3):
d
¼12.37 (CH3), 14.28 (CH3), 24.40 (CH2), 26.92
(CH2), 26.72 (2ꢂCH2), 54.08 (2ꢂCH2), 81.27 (OC), 120.07 (C), 121.82
(CH]), 121.87 (CH]), 122.62 (C), 126.55 (C), 126.85 (4ꢂCH]),
127.15 (2ꢂCH]), 128.01 (4ꢂCH]), 128.37 (CH]), 145.70 (2ꢂC),
146.15 (C), 146.31 (C). Mp 126–128 ꢀC; HRMS calcd for C28H29NO
395.2249, found 395.2253. ESI-MS: m/z¼396 [MþH]þ.
(2ꢂCH2), 54.11 (2ꢂCH2), 82.20 (OC), 114.69 (CH]), 118.20 (C),
124.19 (CH]), 124.89 (C), 126.82 (4ꢂCH]), 127.14 (2ꢂCH]), 127.49
(C), 127.96 (4ꢂCH]), 133.58 (C), 145.71 (2ꢂC), 145.99 (C), 146.40
(C). HRMS calcd for C28H29NO 395.2249, found 395.2242. ESI-MS:
m/z¼396 [MþH]þ.
4.1.1.6. 1-(5,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)pyrrolidine
4.1.1.12. 1-(7,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)pyrrolidine
(6). 1H NMR (250.13 MHz, CDCl3):
d
¼1.76–1.81 (m, 4H), 2.15 (s, 3H),
(12). 1H NMR (250.13 MHz, CDCl3):
d
¼1.76–1.81 (m, 4H), 2.09 (s,
2.18 (s, 3H), 2.84–2.88 (m, 4H), 6.10 (d, J¼9.95 Hz, 1H), 6.62 (s, 1H),
3H), 2.16 (s, 3H), 2.83–2.87 (m, 4H), 6.00 (d, J¼9.63 Hz, 1H), 6.48 (d,
J¼10.11 Hz, 1H), 6.50 (s, 1H), 7.10–7.24 (m, 6H), 7.35–7.38 (m, 4H).
6.74 (d, J¼9.95 Hz, 1H), 7.11–7.25 (m, 6H), 7.36–7.39 (m, 4H). 13C
NMR (62.90 MHz, CDCl3):
d
¼15.84 (CH3), 18.06 (CH3), 29.39
13C NMR (62.90 MHz, CDCl3):
d
¼12.38 (CH3), 15.42 (CH3), 24.25
(2ꢂCH2), 54.06 (2ꢂCH2), 83.24 (OC), 122.16 (CH]), 122.37 (C),
123.93 (CH]), 124.60 (C), 127.25 (C), 128.93 (4ꢂCH]), 129.27
(2ꢂCH]), 130.08 (4ꢂCH]), 130.67 (CH]), 144.58 (C), 147.78
(2ꢂC), 147.88 (C). HRMS calcd for C27H27NO 381.2093, found
381.2089. ESI-MS: m/z¼382 [MþH]þ.
(2ꢂCH2), 52.01 (2ꢂCH2), 82.21 (OC), 113.08 (CH]), 118.14 (C),
124.33 (CH]), 125.07 (C), 126.90 (4ꢂCH]), 127.20 (2ꢂCH]),
127.70 (CH]), 128.03 (4ꢂCH]), 132.38 (C), 142.79 (C), 145.63 (C),
145.81 (2ꢂC). HRMS calcd for C27H27NO 381.2093, found 381.2087.
ESI-MS: m/z¼382 [MþH]þ.
4.1.1.7. 4-(-2,2-Diphenyl-2H-chromen-6-yl)morpholine (7). 1H NMR
4.1.1.13. 1-(3,3-Diphenyl-3H-benzo[f]chromen-8-yl)-1H-pyrrole (13). 1H
(250.13 MHz, CDCl3):
d
¼3.03–3.07 (m, 4H), 3.86 (t, J¼4.74 Hz, 4H),
NMR (250.13 MHz, CDCl3):
d
¼6.34 (d, J¼9.95 Hz, 1H), 6.41–6.42 (m,
6.23 (d, J¼9.79 Hz,1H), 6.62 (d, J¼6.95 Hz,1H), 6.64 (s,1H), 6.76 (dd,
2H), 7.19–7.20 (m, 2H), 7.26–7.40 (m, 8H), 7.51–7.61 (m, 5H), 7.67–7.70
J¼2.84, 8.69 Hz, 1H), 6.91 (d, J¼8.69 Hz, 1H), 7.25–7.49 (m, 10H). 13
C
(m, 2H), 8.03 (d, J¼9.00 Hz, 1H). 13C NMR (62.90 MHz, CDCl3):
¼81.67
d
NMR (62.90 MHz, CDCl3):
d¼50.55 (2ꢂCH2), 66.97 (2ꢂCH2), 82.30
(OC), 109.44 (2ꢂCH]), 113.21 (C), 117.40 (CH]), 118.36 (CH]), 118.59
(2ꢂCH]), 119.92 (CH]), 121.09 (C), 122.08 (CH]), 126.05 (4ꢂCH]),
126.67 (2ꢂCH]), 126.82 (C), 127.00 (4ꢂCH]), 127.34 (CH]), 128.46
(CH]), 128.66 (CH]), 135.57 (C), 143.72 (2ꢂC), 149.42 (C). Mp 186–
190 ꢀC; HRMS calcd for C29H21NO 399.1623, found 399.1617. ESI-MS:
m/z¼400 [MþH]þ.
(OC), 114.71 (CH]), 116.89 (CH]), 117.86 (CH]), 121.44 (C), 123.66
(CH]), 126.97 (4ꢂCH]), 127.40 (2ꢂCH]), 128.04 (4ꢂCH]),
129.66 (CH]), 144.87 (2ꢂC), 145.84 (2ꢂC), 146.63 (C). Mp 155–
156 ꢀC; HRMS calcd for C25H23NO2 369.1729, found 369.1731. ESI-
MS: m/z¼370 [MþH]þ.
4.1.1.8. 1-(2,2-Diphenyl-2H-chromen-6-yl)piperidine (8). 1H NMR
4.1.1.14. 1-(5,8-Dimethyl-2,2-diphenyl-2H-chromen-6-yl)-1H-pyrrole
(250.13 MHz, CDCl3):
d
¼1.42–1.48 (m, 2H), 1.57–1.66 (m, 4H), 2.89–
(14). 1H NMR (250.13 MHz, CDCl3):
d
¼1.94 (s, 3H), 2.21 (s, 3H),
2.93 (m, 4H), 6.10 (d, J¼9.80 Hz, 1H), 6.50 (d, J¼9.80 Hz, 1H), 6.56 (d,
J¼2.52 Hz, 1H), 6.66–6.70 (m, 1H), 6.76 (d, J¼8.69 Hz, 1H), 7.12–7.26
6.15–6.17 (m, 3H), 6.59–6.60 (m, 2H), 6.76 (d, J¼10.11 Hz, 1H), 6.84
(s, 1H), 7.20–7.33 (m, 6H), 7.37–7.41 (m, 4H). 13C NMR (62.90 MHz,
(m, 6H), 7.32–7.37 (m, 4H). 13C NMR (62.90 MHz, CDCl3):
d¼24.14
CDCl3):
d
¼11.95 (CH3), 14.55 (CH3), 80.73 (OC), 107.20 (2ꢂCH]),
(CH2), 26.09 (2ꢂCH2), 52.17 (2ꢂCH2), 82.30 (OC), 115.79 (CH]),
116.73 (CH]), 118.93 (CH]), 121.31 (C), 123.90 (CH]), 127.05
(4ꢂCH]), 127.39 (2ꢂCH]), 128.06 (4CH]), 129.30 (CH]), 145.07
(2ꢂC), 146.36 (C), 147.02 (C). HRMS calcd for C26H25NO 367.1936,
found 367.1931. ESI-MS: m/z¼368 [MþH]þ.
118.65 (C), 119.91 (CH]), 121.44 (2ꢂCH]), 122.40 (C), 125.74
(4ꢂCH]), 126.44 (2ꢂCH]), 126.96 (C), 127.10 (4ꢂCH]), 127.95
(CH]), 128.04 (CH]), 130.20 (C), 144.11 (2ꢂC), 148.76 (C). HRMS
calcd for C27H23NO 377.1780, found 377.1775. ESI-MS: m/z¼378
[MþH]þ.
4.1.1.9. 1-(2,2-Diphenyl-2H-chromen-6-yl)pyrrolidine (9). 1H NMR
4.1.1.15. 1-(2,2-Diphenyl-2H-chromen-6-yl)-1H-pyrrole(15). 1H NMR
(250.13 MHz, CDCl3):
d
¼1.84–1.88 (m, 4H), 3.08–3.13 (m, 4H), 6.11
(250.13 MHz, CDCl3):
d
¼6.17 (d, J¼9.97 Hz, 1H), 6.20 (t, J¼2.21 Hz,
(d, J¼9.80 Hz, 1H), 6.17 (d, J¼2.69 Hz, 1H), 6.30 (dd, J¼2.85, 8.69 Hz,
1H), 6.41 (d, J¼9.79 Hz, 1H), 6.76 (d, J¼8.53 Hz, 1H), 7.11–7.25 (m,
2H), 6.54 (d, J¼9.79 Hz, 1H), 6.85–6.87 (m, 3H), 6.93 (d, J¼2.53 Hz,
1H), 7.04 (dd, J¼2.69, 8.53 Hz, 1H), 7.15–7.26 (m, 5H), 7.27–7.28 (m,
6H), 7.33–7.38 (m, 4H). 13C NMR (62.90 MHz, CDCl3):
d¼24.34
1H), 7.32–7.36 (m, 4H). 13C NMR (62.90 MHz, CDCl3):
d¼81.27 (OC),
(2ꢂCH2), 47.06 (2ꢂCH2), 80.92 (OC), 108.47 (CH]), 111.53 (CH]),
109.81 (2ꢂCH]), 117.24 (CH]), 119.23 (CH]), 119.64 (2ꢂCH]),

9982
E.A. Shilova et al. / Tetrahedron 64 (2008) 9977–9982
4. (a) McArdle, C. B. Applied Photochromic Systems; Blackie: London, 1992; (b)
Knowles, D.B. U.S. Patent 5,238,981, 1994.
5. (a) Bamfield, P. Chromic Phenomena-Technological Applications of Colour Chem-
istry; The Royal Society of Chemistry: Cambridge, 2001; p. 19; (b) Christiea, R.
M.; Hepworth, J. D.; Gabbutt, C. D.; Rae, S. Dyes Pigm. 1997, 35, 339.
6. Muci, A.; Buchwald, S. Top. Curr. Chem. 2002, 219, 131.
121.74 (C), 122.10 (CH]), 122.91 (CH]), 127.01 (4ꢂCH]), 127.68
(2ꢂCH]), 128.21 (4ꢂCH]), 130.20 (CH]), 134.89 (C), 144.55
(2ꢂC), 150.47 (C). Mp 100–102 ꢀC; HRMS calcd for C25H19NO
349.1467, found 349.1461. ESI-MS: m/z¼350 [MþH]þ.
7. Wolf, J. P.; Buchwald, S. L. J. Org. Chem. 2000, 65, 1144.
8. Yang, B. H.; Buchwald, S. L. J. Organomet. Chem. 1999, 576, 125.
9. Old, D. W.; Harris, M. C.; Buchwald, S. L. Org. Lett. 2000, 2, 1403.
10. Shilova, E. A.; Moustrou, C.; Samat, A. Tetrahedron Lett. 2005, 46, 8857.
11. Shilova, E. A.; Perevalov, V.; Samat, A.; Moustrou, C. Tetrahedron Lett. 2007, 48,
4127.
Acknowledgements
We are very much indebted to Dr. Jerome Courcambeck (Gen-
oscience, Marseille, France) for generous assistance. We thank
Spectropole (Universites Aix-Marseille I et III, Marseille, France) for
´
12. Bougdid, L.; Heynderickx, A.; Delbaere, S.; Moustrou, C. Tetrahedron 2007, 63,
8242.
mass spectrometry study.
13. Frigoli, M.; Moustrou, C.; Samat, A.; Gugliemetti, R. Eur. J. Org. Chem. 2003, 2799.
14. The following crystal structure has been deposited at the Cambridge Crystal-
lographic Data Centre and allocated the deposition number CCDC 661390.
15. Photochemial mesures were performed in acetonitrile solutions (C¼0.
84H10ꢁ5 M) of spectrometric grade at 20E. The analysis cell was placed in
sample chamber in Cary 50 Scan spectrophotometer. Solutions were stirred
continuously during experiments. An Oriel-150-W-high-pressure Xe lamp was
used for irradiation, 120 mW/cm2.
16. Coen, S.; Lehadus, N.; Moustrou, C.; Samat, A.; Gugliemetti, R. Heterocycl.
Commun. 2002, 8, 27.
17. Padwa, A.; Lee, A. G. J. Chem. Soc., Chem. Commun. 1972, 795.
18. Demadrille, R.; Moustrou, C.; Samat, A.; Guglielmetti, R. Heterocycl. Commun.
1999, 5, 123.
References and notes
1. Photochromism: Molecules and Systems; Dhrr, H., Bouas-Laurent, H., Eds.;
Elsevier: Amsterdam, 1990; p 314.
2. (a) Organic Photochromic and Thermochromic Compounds; Crano, J. C., Gu-
glielmetti, R. J., Eds.; Kluwer Academic/Plenum: New York, NY, 1999; Vol. 1; (b)
Organic Photochromic and Thermochromic Compounds; Crano, J. C., Guglielmetti,
R. J., Eds.; Kluwer Academic/Plenum: New York, NY, 1999; Vol. 2.
3. Gemert, B. V. In Organic Photochromatic and Thermochromic Compounds; Crano,
J. C., Guglielmetti, R. J., Eds.; Kluwer Academic/Plenum: New York, NY, 1998;
Vol. 1, Chapter 3.