5-Hydroxy substituted naphthofurans and naphthothiazoles as precursors of photochromic benzochromenes

Article abstract of DOI:10.1016/j.tet.2014.10.043

3-Benzoylnaphtho[1,2-b]furan-5-ol forms a photochromic benzochromene upon reaction with a 1,1-diarylprop-2-yn-1-ol affording a red coloured photomerocyanine, with a half-life of 2.3 min, upon UV-irradiation. Retention of the initial 1,4-oxygenation pattern of the naphthalene moiety through replacement of the furan unit with a methoxy group led to a benzochromene, which developed a similar red colour upon UV-irradiation but was more persistent with a half-life of over 42 min. Treatment of the 3-benzoylnaphtho[1,2-b]furan-5-ol with a 1,1,3-triarylprop-2-yn-1-ol similarly afforded a benzochromene, which did not display any photochromism at ambient temperature as a consequence of steric interactions in the photomerocyanines. The synthesis of N-(5-hydroxynaphtho[1,2-d]thiazol-2-yl)acetamide, as a precursor to a photochromic hetero-fused benzochromene, by the mild selective deprotection of the O-acetyl group of 2-acetamidonaphtho[1,2-d]thiazol-5-yl acetate was complicated by a facile, competitive, oxidative dimerisation to afford a novel [2,2′-binaphthothiazole]-1,1′-diol.

Full text of DOI:10.1016/j.tet.2014.10.043

Tetrahedron 70 (2014) 9352e9358
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
5-Hydroxy substituted naphthofurans and naphthothiazoles as
precursors of photochromic benzochromenes
*
Stuart Aiken, Ben Allsopp, Kathryn Booth, Christopher D. Gabbutt, B. Mark Heron ,
Craig R. Rice
Department of Chemical Sciences, School of Applied Science, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 July 2014
Received in revised form 7 October 2014
Accepted 17 October 2014
Available online 23 October 2014
3-Benzoylnaphtho[1,2-b]furan-5-ol forms a photochromic benzochromene upon reaction with a 1,1-
diarylprop-2-yn-1-ol affording a red coloured photomerocyanine, with a half-life of 2.3 min, upon UV-
irradiation. Retention of the initial 1,4-oxygenation pattern of the naphthalene moiety through re-
placement of the furan unit with a methoxy group led to a benzochromene, which developed a similar
red colour upon UV-irradiation but was more persistent with a half-life of over 42 min. Treatment of the
3-benzoylnaphtho[1,2-b]furan-5-ol with a 1,1,3-triarylprop-2-yn-1-ol similarly afforded a benzochro-
mene, which did not display any photochromism at ambient temperature as a consequence of steric
interactions in the photomerocyanines. The synthesis of N-(5-hydroxynaphtho[1,2-d]thiazol-2-yl)acet-
amide, as a precursor to a photochromic hetero-fused benzochromene, by the mild selective de-
protection of the O-acetyl group of 2-acetamidonaphtho[1,2-d]thiazol-5-yl acetate was complicated by
a facile, competitive, oxidative dimerisation to afford a novel [2,20-binaphthothiazole]-1,10-diol.
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Photochromism
Synthesis
Benzochromene
Oxidative dimerisation
Quinone
1. Introduction
The photochromic response of the isomeric angular benzo-
chromenes (naphthopyrans) 1 and 2 (Fig. 1) has been widely
exploited in commercial photochromic ophthalmic sun-lenses,1e7
and has been studied by several academic research groups.8e10
Interest in the application of the 2H-naphtho[1,2-b]pyran system
2 increased following the disclosure that the rate of fade of the
coloured merocyanine dye could be controlled by the placement of
substituents at the 5- and/or 5- and 6-positions.11 A great number
of studies followed describing the synthesis and properties of 2H-
naphtho[1,2-b]pyrans with either a 5,6-fused carbocyclic or 5,6-
fused heterocyclic ring.8,9,12e17
One synthetic strategy to access 2H-naphtho[1,2-b]pyrans with
a 5,6-fused heterocyclic ring commences from 1,4-naphthoquinone,
which is elaborated into a hetero-fused 1-naphthol and sub-
sequently transformed into the naphthopyran by the established
acid-catalysed reaction with
a
1,1-diarylprop-2-yn-1-ol.18 The
foregoing strategy may be exemplified by the condensation of
1,4-naphthoquinone with, for example, 3-methoxyphenol,19 1,3-
dihydroxynaphthalene20 or 3-aminocrotonates21 to afford hetero-
Fig. 1. Isomeric naphthopyrans 1 and 2 (Ar¼aryl).
fused 1-naphthols, which upon subsequent reaction with 1,1-
bis(4-methoxyphenyl)prop-2-yn-1-ol afford the red-colouring
hetero-fused naphthopyrans 3, 4 and 5, respectively (Fig. 2).
* Corresponding author. Fax: þ44 (0)1484 472182; e-mail address: M.Heron@
hud.ac.uk (B.M. Heron).
http://dx.doi.org/10.1016/j.tet.2014.10.043
0040-4020/Ó 2014 Elsevier Ltd. All rights reserved.

S. Aiken et al. / Tetrahedron 70 (2014) 9352e9358
9353
Fig. 2. Hetero-fused naphtho[1,2-b]pyrans derived from 1,4-naphthoquinone.
The condensation of thiourea22 and of enaminoketones derived
from acetophenones23,24 with 1,4-naphthoquinone results in the
naphthalene unit, was examined. Reaction of 4-methoxy-1-
naphthol with 8, under identical conditions to those employed to
access 9, gave 10 in moderate yield according to our previously
published report.26
The photochromic response of 9 and 10 were next examined in
acetone solution (Scheme 3). The absorption spectra of 9, pre- and
post-UV-irradiation, are presented (Fig. 3). The solution of 9 before
UV-irradiation is essentially colourless and becomes intensely
thiazole-fused (2-aminonaphtho[1,2-d]thiazol-5-ol)
6 and the
furan-fused (3-benzoylnaphtho[1,2-b]furan-5-ol) 7 ‘1-naphthols’,
respectively (Scheme 1). To the best of our knowledge the appli-
cation of the readily available 6 and 7 for the synthesis of photo-
chromic naphthopyrans appears to have been overlooked and we
now describe our preliminary explorations in this area.
Scheme 1. Synthesis of hetero-fused naphthols 6 and 7.
2. Discussion
coloured after irradiation at 365 nm for 2 min with lmax at 496 nm
and a small shoulder at ca. 425 nm. The decay of the intensity of the
absorption at 496 nm was measured as a function of time and the
The synthesis of 3-benzoylnaphtho[1,2-b]furan-5-ol 7 was ac-
complished in 75% yield according to the general literature pro-
cedure.23,24 The fact that 7 was only moderately soluble in toluene
prompted us to adopt alternative reaction conditions to our usual
protocol (acidic alumina suspended in toluene) for the formation of
naphthopyrans.18 Thus heating a mixture of 7, propynol 8, PPTS and
trimethyl orthoformate in 1,2-dichloroethane under reflux25 gave,
upon removal of the solvent and crystallisation from EtOAc/hexane,
the pure naphthopyran 9 as pale pink microcrystals in 52% yield
(Scheme 2). Formation of 9 was confirmed by 1H NMR spectros-
copy, which displayed a characteristic doublet for the pyran ring
half-life (t ) was calculated to be 2.3 min.
½
The absorption spectrum of 10 before UV irradiation indicated
a slightly more intense absorbing inactivated state relative to that
of 9, and upon UV irradiation the formation of a deep maroon so-
lution was observed with an absorption maximum at 507 nm and
a dramatically longer half-life of 42.3 min (Fig. 3). Clearly the
presence of the benzoylfuran unit in 9 results in an appreciable
decrease in t relative to that for 10; such a feature is in accord with
½
known substituent effects on t for other photochromic 2H-naph-
½
tho[1,2-b]pyrans.8,11 Indeed, examination of the isomeric photo-
merocyanines 9a and 9b (Scheme 3) indicate areas of significant
steric interactions between the benzoylfuran unit and the allyli-
dene moiety, which favour rapid recyclisation to the pyran 9 with
proton (5-H) at
NMR spectrum exhibited a signal at
82.2 for C-6.
d
6.13 with a coupling constant of 9.9 Hz.8 The 13C
190.5 for the C]O and at
d
d
Scheme 2. Synthesis of photochromic naphthopyrans 9 and 10.
In order to assess the influence of the fused benzoylfuran ring on
loss of colour; such steric interactions are absent in photo-
the photochromic response of 9, the synthesis of the comparative
example 10, which retains the 1,4-oxygenation pattern in the
merocyanines 10a and 10b leading to greater persistence of the
colour. Additional consequences of the presence of
a C-5

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S. Aiken et al. / Tetrahedron 70 (2014) 9352e9358
Scheme 3. Potential photomerocyanines resulting from 9 and 10 after UV-irradiation.
compound 9 pre-UV
compound 10 pre-UV
compound 9 post-UV
compound 10 post-UV
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
a
b
s
o
r
b
a
n
c
e
350
400
450
500
550
600
650
700
wavelength / nm
Fig. 3. Photochromic response of naphthopyrans 9 and 10.
substituent are the hypsochromic shift of lmax and the emergence
of a weak shoulder at ca. 425 nm in the post UV-irradiation spec-
trum of 9; the latter feature is absent in the spectrum of 10.
Given the marked influence of the fused benzoylfuran ring on
the photochromic response of 9 we were keen to examine an ad-
ditional steric effect induced by the incorporation of an aryl ring at
C-4 of 9 leading to compound 12. Thus heating 7 with the propynol
11, derived from the addition of 4-tolylethynyllithium to 4,40-
dimethoxybenzophenone according to our literature procedure,18
gave the naphthopyran 12 in 73% yield after 2ꢀ crystallisation
from EtOAc/hexane (Scheme 4). From the initial crystallisation li-
benzoyl group in 10 (1651 cmꢁ1) and 12 (1704 cmꢁ1) revealed
a 53 cmꢁ1 difference, which may be attributed to the non-planarity
of the C]O group in 12, thereby decreasing any conjugative effect
with the furan ring oxygen atom and phenyl ring. A crystal struc-
ture of 12 (Fig. 4) was obtained from a crystal grown by the slow
evaporation of a hexane/CH2Cl2 solution of 12 and reveals the steric
congestion between the 3-benzoyl and 4-tolyl groups.27 Further-
more, from the crystal structure of 12, it is apparent that the C]O
group is neither planar with the furan unit (torsion angle
C21eC26eC22eO4 w24ꢂ) nor the phenyl ring (torsion angle
C38eC33eC22eO4 w35ꢂ).
quors of 12 a small amount of the
a
,
b
-unsaturated ketone 13 (5.7%)
No photochromic response of 12 could be observed even upon
UV-irradiation of a solution cooled in a CO2(s)/acetone cooling bath.
Presumably the steric interactions between the benzoyl and tolyl
groups disfavour the ring-opening and isomerisation processes.
We next examined the reactivity of the thiazole-fused naphthol
6. The reaction of 6 with propynol 8 under a variety of reaction
conditions including acidic alumina in PhMe,18 4-TsOH in PhMe28
and PPTS with (MeO)3CH in 1,2-DCE resulted in very complex,
was obtained by column chromatography with EtOAc/hexane.
The structure of 12 was elucidated using 1H NMR spectroscopy,
which indicated a singlet at
respectively. The 13C NMR spectrum displayed a low field signal at
187.5, which is assigned to the C]O group. Noticeably, this signal
resonates slightly upfield of the comparable signal in 9 ( 190.5).
Comparison of the position of the IR stretching bands of the
d 7.79 and at d 5.96 for 2-H and 5-H,
d
d

S. Aiken et al. / Tetrahedron 70 (2014) 9352e9358
9355
Scheme 4. Synthesis of photochromic naphthopyran 12.
in 65% yield. Potassium carbonate in aq methanol at rt was selected
for the O-deacetylation of 14 as a mild method for the selective
cleavage of the O-Ac function.29 Two components were isolated
when 14 was deacetylated; the 2,20-binaphthalen-1,1-diol 15 (25%)
and a lesser amount of the target naphthol 16 (14%), which
appeared to darken (become more intense maroon/purple) upon
standing and was thus reacted directly with propynol 8. The 1H and
13C NMR spectra of 15 were relatively simple as a consequence of
the symmetrical nature of the molecule and are in accord with
those of other symmetrical [2,20-binaphthalene]-1,10-diols.30,31
However the absence of a signal for 4-H (naphthol 16 displayed
a singlet at
d 7.36 for 4-H) combined with mass spectrometry
(C26H18N4O4S2 found MþHþ, 515.0837) confirmed the dimeric
structure 15. To further establish the dimerisation of 14 during the
deacetylation reaction, 15 was re-acetylated (Ac2O, Et3N, 100 ꢂC),
which afforded a new tetra-acetylated compound 17 in 64% yield
(C30H22N4O6S2 found MþHþ, 599.1049) rather than regenerated 14.
The formation of the binaphthol 15 by an oxidative CeC cou-
pling may be rationalised by initial methanoloysis of the OAc group
of 14 to afford the ‘naphthoxide’ 20 followed by air oxidation to the
extended quinoneimine intermediate 21. Subsequently generated
20 may either oxidise to form further 21 or may add to 21 to afford
the diketone 22, which tautomerises to afford 15 (Scheme 6). To
support the proposed air oxidation process the methanolysis of 14
was repeated under an atmosphere of nitrogen, which again
resulted in the formation of a mixture of 15 (11%) and 16 (35%),
though in this instance 16 was now the major product.
Fig. 4. Crystal structure of 12 (thermal ellipsoids shown at 50% probability).
deeply coloured, reaction products. It was suspected that the free
amine group at 2-C may interfere with the expected reactivity, and
thus the protection of the NH2 function of 6 with an acetyl group
was explored (Scheme 5). Treatment of 6 with Ac2O in the presence
of Et3N gave the diacetylated product 14 (dAc 2.25 and 2.49; d4-H 7.9)
Scheme 5. Transformation of 2-aminonaphtho[1,2-d]thiazol-5-ol 6.

9356
S. Aiken et al. / Tetrahedron 70 (2014) 9352e9358
Scheme 6. Proposed oxidative dimerisation process for the formation of 15.
Unfortunately attempts to obtain the pyran 18 by reaction of 16
2-aminium chloride in 94% yield, mp>300 ꢂC (lit. Mp>320 ꢂC22),
nmax 3445, 3338, 327, 3062, 1582, 1522, 1401, 1317, 1246, 1071, 892,
with 8 resulted in a complex mixture from which a pure compound
could not be obtained. However, the 1H NMR spectrum of the
‘cleanest’ fraction from extensive flash column chromatography
was suggestive of an equilibrium mixture of pyran 18 (d5-H 6.27, d,
752, 674 cmꢁ1
, dH (DMSO-d6) 7.27 (1H, s, 4-H), 7.49e7.53 (1H, m, 7-
H or 8-H), 7.59e7.62 (1H, m, 7-H or 8-H), 8.18 (1H, d, J 8.3 Hz, 9-H),
8.31 (1H, d, J 8.2 Hz, 6-H), 8.33 (2H, br s, 2-NH2 [D2O exchanges]),
10.33 (1H, br s, OH [D2O exchanges]).
0
J¼9.8 Hz) and dienone 19 (d2 -H 7.94, d, J¼13.0 Hz).
3. Conclusion
4.3. 3-Benzoylnaphtho[1,2-b]furan-5-ol, 7
3-Benzoylnaphtho[1,2-b]furan-5-ol readily forms benzochro-
menes in good yield upon acid-catalysed reaction with di-8 and tri-
11 aryl substituted propynols. Whilst the benzochromene 12 de-
rived from 11 exhibited no photochromic response even at low
temperature as a consequence of steric interactions, the benzo-
chromene 9 displayed photochromism with the development of
a red colour with a fade rate comparable with those of several
commercial photochromic compounds. The benzoylfuran unit of 9
was demonstrated to be responsible for the relatively short half-life
of the photogenerated colour viz. benzochromene 10 for which the
photogenerated colour was particularly persistent. Attempts to
3-Benzoylnaphtho[1,2-b]furan-5-ol, 7, was prepared according
to the literature protocol12 in 75% yield, mp 275e277 ꢂC (lit. Mp
272e274 ꢂC23), nmax 3212 (br), 1611, 1589, 1344, 1250, 1145, 1076,
881, 768, 720, 701, 692, 680, 646 cmꢁ1
, dH (DMSO-d6) 7.57e7.63 (4H,
m, AreH, 4-H), 7.69e7.73 (2H, m, AreH), 7.93e7.96 (2H, m, AreH),
8.22 (1H, d, J 8.1 Hz, 6-H or 9-H), 8.28 (1H, d, J 8.3 Hz, 6-H or 9-H),
8.72 (1H, s, 2-H), 10.31 (1H, s, OH [D2O exchanges]); dC (DMSO-d6)
100.60, 119.80, 121.22, 121.41, 121.70, 123.80, 123.97, 125.55, 127.94,
129.25, 129.28, 133.10, 139.21, 145.01, 151.38, 153.38, 190.36 (Found
MþHþ, 289.0860; C19H12O3 requires MþHþ, 289.0859).
prepare
a
photochromic benzochromene from either 2-
4.4. Method for the preparation of 2-acetamidonaphtho[1,2-d]
aminonaphtho[1,2-d]thiazol-5-ol or the N-acetylated derivative
16 were unsuccessful. During the preparation of 16 a facile oxida-
tive dimerisation was observed leading to a novel [2,20-binaph-
thalene]-1,10-diol derivative. The exploration of heterocyclic fused
photochromic benzochromenes from readily accessible hydroxy
substituted heterocycles is on-going.
thiazol-5-yl acetate 14
Triethylamine (3 mL, 21.5 mmol) was added in a single portion
to a suspension of 2-aminonaphtho[1,2-d]thiazol-5-ol 6 (6.0 g,
27.7 mmol) in acetic anhydride (25 mL) and the mixture was heated
to 120 ꢂC for 2 h and then cooled to room temperature. The
resulting suspension was diluted with water (150 mL) and stirred
for 2 h at room temperature. The solid was collected by vacuum
filtration, washed well with water and air dried to afford the title
compound 14 as a pale pink powder 64.7%, mp>300 ꢂC; nmax 3164,
3065, 2971,1753,1645,1588,1548,1366,1300,1211,1192,1064, 902,
4. Experimental
4.1. Equipment and reagents
Unless otherwise stated, reagentswereusedas supplied bymajor
chemical suppliers. NMR spectra were recorded on a Bruker Avance
400 MHz spectrophotometer (1H NMR 400 MHz, 13C NMR 100 MHz)
for sample solutions in either CDCl3, DMSO-d6 or d6-acetone. FTIR
spectra were recorded on a Nicolet 38 spectrophotometer system
equipped with a diamond ATR attachment (neat sample). All com-
poundswerehomogeneousbyTLC usinga rangeofeluent systemsof
differing polarity. High resolution mass spectra [Thermo (Finnigan)
LTQ OrbitrapXL] were recorded at the National EPSRC Mass Spec-
trometry Service Centre, Swansea. UV-visible spectra were recorded
in spectroscopic grade acetone solutions of the samples (10 mm
pathlength quartz cuvette, PTFE capped, concentration ranges ca.
3ꢀ10ꢁ4e10ꢁ5 mol dmꢁ3) using an Agilent Technologies Cary 60
spectrophotometer equipped with a temperature controlled (20 ꢂC)
stirred cell. Irradiation of the stirred sample solutions was accom-
plished with a Spectroline 8 Watt TLC inspection lamp at 365 nm.
845, 754, 685 cmꢁ1
; dH (DMSO-d6) 2.25 (3H, s, Ac), 2.49 (3H, s, Ac),
7.63e7.67 (1H, m, 7-H or 8-H), 7.72e7.76 (1H, m, 7-H or 8-H), 7.93
(1H, s, 4-H), 7.98 (1H, d, J 8.2 Hz, 9-H), 8.54 (1H, d, J 8.1 Hz, 6-H),
12.63 (1H, br s, NH); dC (DMSO-d6) 21.18, 23.14, 112.93, 122.52,
123.61, 125.88, 126.75, 126.82, 127.52, 127.67, 142.94, 143.01, 158.64,
169.82, 170.25 (Found MþHþ, 301.0644; C15H12N2O3S requires
MþHþ, 301.0641).
4.5. Methodfor the selective hydrolysis of2-acetamidonaphtho
[1,2-d]thiazol-5-yl acetate 14
Potassium carbonate (4.0 g, 28.9 mmol) was added in a single
portion to a stirred suspension of 2-acetamidonaphtho[1,2-d]thia-
zol-5-yl acetate 14 (5.0 g, 16.6 mmol) in methanol (50 mL) at room
temperature. The suspension was stirred for 4 h during, which time
the colour of the solution intensified (pale pink/red) and the
suspension gradually dissolved. Dilution with water (200 mL) gave
a pink precipitate, which was collected by vacuum filtration and
washed well with water. The isolated crude pink solid (3.63 g) was
boiled in methanol for 5 min and then cooled to room temperature.
The resulting pale pink solid was collected by vacuum filtration and
4.2. 2-Aminonaphtho[1,2-d]thiazol-5-ol, 6
2-Aminonaphtho[1,2-d]thiazol-5-ol, 6, was prepared according
to the literature protocol22 from 5-hydroxynaphtho[1,2-d]thiazol-

S. Aiken et al. / Tetrahedron 70 (2014) 9352e9358
9357
washed with methanol (30 mL) to afford N,N0-(5,50-dihydroxy-
4.8. Method for the preparation of photochromic
benzochromenes
[4,40-binaphtho[1,2-d]thiazole]-2,20-diyl)diacetamide 15, 25.4%,
mp>300 ꢂC, nmax 3371, 1669, 1578, 1539, 1403, 1369, 1284, 1208,
987, 770, 678, 528 cmꢁ1
;
dH (DMSO-d6) 2.14 (6H, s, NAc), 7.62e7.66
A solution of the naphthol (1 mol equiv) and the appropriate 1,1-
bis(4-methoxyphenyl)prop-2-yn-1-ol (1 mol equiv), in the pres-
ence of pyridinium p-toluenesulfonate (PPTS) (5 mole %) and tri-
methyl orthoformate (2 mol equiv) in 1,2-dichloroethane (150 mL),
was heated under reflux for up to 4 h (the reaction time being
determined by TLC examination of the reaction mixture). The
cooled solvent was removed under vacuum to afford the crude
product, which was either purified by flash column chromatogra-
phy or by crystallisation. The following compounds were obtained
in this manner:
(2H, m, 7-H or 8-H), 7.73e7.77 (2H, m, 7-H or 8-H), 8.40 (2H, d, J
8.4 Hz, 9-H), 8.54 (2H, d, J 8.4 Hz, 6-H), 9.42 (2H, s, OH [D2O ex-
changes]), 12.40 (2H, s, NH [D2O exchanges]); dC (DMSO-d6) 23.00,
110.77, 123.20, 124.06, 125.52, 125.65, 127.53, 128.09, 130.26, 137.83,
148.07, 155.55, 169.18 (Found MþHþ, 515.0837; C26H18N4O4S2 re-
quires MþHþ, 515.0842). The combined methanol filtrate and
washings were evaporated to afford N-(5-hydroxynaphtho[1,2-d]
thiazol-2-yl)acetamide 16, as a pale pink-maroon solid, 14.0%, nmax
3186 (br), 2980, 1667, 1585, 1538, 1467, 1274, 1243, 1072, 761,
682 cmꢁ1
; dH (DMSO-d6) 2.21 (3H, s, NAc), 7.36 (1H, s, 4-H),
7.52e7.56 (1H, m, 7-H or 8-H), 7.63e7.66 (1H, m, 7-H or 8-H), 8.22
(1H, d, J 8.3 Hz, 9-H), 8.42 (1H, d, J 8.2 Hz, 6-H),10.37 (1H, s, OH [D2O
exchanges]), 12.38 (1H, s, NH [D2O exchanges]); dC (DMSO-d6)
23.08, 100.76, 123.06, 123.32, 124.57, 125.15, 127.31, 127.90, 128.35,
137.78, 150.55, 155.21, 169.23 (Found MþHþ, 259.0529;
4.8.1. 3-Benzoyl-6,6-bis(4-methoxyphenyl)-6H-benzo[h]furo[3,2-f]
chromene
9. 3-Benzoyl-6,6-bis(4-methoxyphenyl)-6H-benzo[h]
furo[3,2-f]chromene 9 from 7 and 8 as pale pink microcrystals after
crystallisation from EtOAc and hexane, 52.4%, mp 188e190 ꢂC; nmax
2831, 1651, 1606, 1506, 1351, 1236, 1173, 1028, 1017, 876, 836, 726,
C
13H10N2O2S requires MþHþ, 259.0536).
706, 683, 663, 646 cmꢁ1
; dH (CDCl3) 3.76 (6H, s, OMe), 6.13 (1H, d, J
9.9 Hz, 5-H), 6.82e6.85 (4H, m, AreH), 7.44e7.47 (4H, m, AreH),
7.51e7.65 (6H, m, AreH, 4-H), 7.93e7.95 (2H, m, AreH), 8.02 (1H, s,
2-H), 8.19 (1H, d, J 7.8 Hz, AreH), 8.45 (1H, d, J 8.1 Hz, AreH); dC
(CDCl3) 55.22, 82.22, 110.56, 113.38, 117.80, 119.99, 121.17, 122.83,
123.08, 123.64, 124.09, 125.90, 127.09, 127.11, 128.28, 128.62, 129.67,
132.92, 137.34, 139.29, 145.27, 147.04, 151.68, 158.84, 190.48 (Found
MþHþ, 539.1844; C36H26O5 requires MþHþ, 539.1853).
4.6. Method for the acylation of N,N0-(5,50-dihydroxy-[4,40-
binaphtho[1,2-d]thiazole]-2,20-diyl)diacetamide 15
Triethylamine (1.0 mL, 7.2 mmol) was added in a single portion
to a suspension of N,N0-(5,50-dihydroxy-[4,40-binaphtho[1,2-d]thi-
azole]-2,20-diyl)diacetamide 15 (1.0 g, 1.9 mmol) in acetic anhy-
dride (10 mL) and the mixture was heated to 100 ꢂC for 2 h and then
cooled to room temperature. The resulting suspension was diluted
with water (100 mL) and stirred for 2 h at room temperature. The
precipitated tan solid was collected by vacuum filtration, washed
well with water and air dried to afford 2,20-diacetamido-[4,40-
binaphtho[1,2-d]thiazole]-5,50-diyl diacetate 17 as a pale pink
powder after washing with hot EtOAc, 64.4%, mp>300 ꢂC (begins to
darken at 180 ꢂC), nmax 3330, 2981, 1771, 1738, 1685, 1528, 1365,
4.8.2. 3-Benzoyl-6,6-bis(4-methoxyphenyl)-4-(4-methylphenyl)-6H-
benzo[h]furo[3,2-f]chromene
12. 3-Benzoyl-6,6-bis(4-methoxy
phenyl)-4-(4-methylphenyl)-6H-benzo[h]furo[3,2-f]chromene 12
from 7 and 11 as an off white ‘fluffy’ solid after 2ꢀ crystallisation
from EtOAc/hexane 72.9%, mp 175e177 ꢂC; nmax 3131, 2982, 1704,
1608, 1508, 1380, 1248, 1214, 1173, 1096, 963, 829, 762 cmꢁ1
; dH
(CDCl3) 2.03 (3H, s, Me), 3.76 (6H, s, OMe), 5.96 (1H, s, 5-H),
6.82e6.91 (8H, m, AreH), 7.30e7.34 (2H, m, AreH), 7.52e7.55 (7H,
m, AreH), 7.61e7.69 (2H, m, AreH), 7.79 (1H, s, 2-H), 8.25 (1H, d, J
8.0 Hz, AreH), 8.56 (1H, d, J 8.0 Hz, AreH); dC (CDCl3) 20.89, 55.21,
82.56, 111.87, 113.33, 117.55, 120.16, 121.79, 123.42, 124.24, 124.87,
125.90, 126.73, 127.47, 127.79, 127.85, 128.45, 129.06, 129.81, 132.57,
135.89, 136.62, 136.70, 136.83, 137.30, 146.88, 147.07, 147.18, 158.88,
187.55 (Found MþHþ, 629.2320; C43H32O5 requires MþHþ,
629.2323) and 1,1-bis(4-methoxyphenyl)-3-(4-methylphenyl)prop-2-
enone 13 after elution of the concentrated crystallisation liquors
from chromatography silica with 50% EtOAc/hexane as yellow
micro-crystals 5.7%, mp 93e95 ꢂC; nmax 2933, 2836, 1654, 1603,
1348, 1238,1207, 1166,1157, 1021, 767, 618 cmꢁ1
; dH (DMSO-d6) 2.03
(6H, s, Ac), 2.15 (6H, s, Ac), 7.71e7.74 (2H, m, AreH), 7.81e7.86 (2H,
m, AreH), 8.03 (2H, d, J 8.3 Hz, AreH), 8.63 (2H, d, J 8.2 Hz, AreH),
12.72 (2H, br s, NH); dC (DMSO-d6) 21.24, 23.06, 119.38, 123.55,
123.79, 126.19, 127.28, 127.48, 127.60, 128.43, 140.90, 143.13, 158.85,
169.33, 169.95 (Found MþHþ, 599.1049; C30H22N4O6S2 requires
MþHþ, 599.1054).
4.7. Preparation of 1,1-bis(4-methoxyphenyl)-3-(4-methyl-
phenyl)prop-2-yn-1-ol 11
1506, 1461, 1289, 1244, 1172, 1112, 1029, 827, 753, 575, 549 cmꢁ1
; dH
n-BuLi (2.5 M in hexanes, 41.4 mmol, 16.6 mL) was added slowly
to a cold (0 ꢂC) stirred solution of 4-ethynyltoluene (39.4 mmol,
4.58 g) in anhydrous THF (150 mL) under nitrogen. Upon completion
of the addition, the cold solution was stirred for 30 min and then 4,4-
dimethoxybenzophenone (35.8 mmol, 8.68 g) was added in a single
portion and the mixture stirred for 2 h. The resulting mixture was
poured into water (250 mL) containing brine (30 mL), and the or-
ganic layer was separated and the aqueous layer extracted with
EtOAc (3ꢀ50 mL). The organic extracts were combined and washed
with water (2ꢀ100 mL) and dried over anhyd. Na2SO4. Removal of
the solvent afforded the title compound 11 (12.1 g, 94%) as a very
viscous pale yellow oil, nmax 3450, 2952, 2835,1606,1584,1505,1461,
(CDCl3) 2.39 (3H, s, Me), 3.80 (3H, s, OMe), 3.85 (3H, s, OMe), 6.81
(2H, d, J 8.3 Hz, AreH), 6.89 (2H, d, J 8.4 Hz, AreH), 7.01 (1H, s, 2-H),
7.13 (2H, d, J 8.3 Hz, AreH), 7.19 (2H, d, J 7.8 Hz, tolyl-H), 7.34 (2H, d, J
8.4 Hz, AreH), 7.84 (2H, d, J 7.8 Hz, tolyl-H); dC (CDCl3) 21.67, 55.20,
55.41, 113.44, 113.79, 121.63, 128.84, 129.09, 130.29, 131.43, 131.59,
134.41, 136.23, 143.21, 154.51, 159.79, 160.72, 192.09 (Found
[MþH]þ¼359.1636C24H22O3 requires [MþH]þ¼359.1642).
Acknowledgements
We thank the EPSRC for access to the National Mass Spec-
trometry Service, Swansea and Vivimed Laboratories (Europe) Ltd.,
for the provision of consumables for this project.
1301, 1243, 1168, 1031, 986, 899, 8115, 742, 587, 526 cmꢁ1
; dH (CDCl3)
2.38 (3H, s, Me), 3.29 (1H, s, OH (D2O exchangeable)), 3.80 (6H, s,
OMe), 6.87e6.93 (4H, m, AreH), 7.15 (2H, d, J 7.88 Hz, tolyl-H),
7.40e7.43 (2H, m, tolyl-H), 7.60e7.65 (4H, m, AreH); dC (CDCl3)
21.56, 55.31, 74.18, 86.95, 91.65, 113.56, 119.58, 127.47, 129.13, 131.70,
137.85, 138.74, 158.98. Found [MꢁH2OþH]þ¼341.1532C24H22O3 re-
quires [MꢁH2OþH]þ¼341.1536.
References and notes
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source and a cold stream of N2 gas. Selected crystal data for 12: C43H32O5,
ꢀ
ꢀ
ꢀ
M¼628.68, monoclinic, a¼11.7292(7) A, b¼17.0245(9) A, c¼15.9462(8) A, b¼97.
3
1836(15) , V¼3159.2(3) A , density¼1.322 g cmꢁ3, T¼150 K, space group P21/n,
ꢂ
ꢀ
Z¼4,
m
¼0.086 mmꢁ1
, 45,545 measured reflections, 9745 independent re-
flections (Rint¼0.0988). The final R1 values were 0.0707 (I>2
s(I)). The final
11. Anonymous, Research Disclosure 1994, 361, 266.
wR(F2) values were 0.1448 (I>2
s(I)). The final R1 values were 0.1778 (all data).
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The final wR(F2) values were 0.1843 (all data). The goodness of fit on F2 was 1.
ꢀꢁ3
036. Largest peak and hole 0.272 and ꢁ0.334 e A . Crystallographic data
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