Photochemical intramolecular cyclization of o-alkynylaryl isocyanides with organic dichalcogenides leading to 2,4-bischalcogenated quinolines

Article abstract of DOI:10.1039/c0ob01168a

When a mixture of o-alkynylaryl isocyanides and organic dichalcogenides such as diselenides or ditellurides was irradiated with light of wavelength over 300 or 400 nm, the intramolecular cyclization of the isocyanides took place to afford the correspondin

Full text of DOI:10.1039/c0ob01168a

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PAPER
Photochemical intramolecular cyclization of o-alkynylaryl isocyanides with
organic dichalcogenides leading to 2,4-bischalcogenated quinolines†
Takenori Mitamura, Kimiyo Iwata, Akihiro Nomoto and Akiya Ogawa*
Received 13th December 2010, Accepted 22nd March 2011
DOI: 10.1039/c0ob01168a
When a mixture of o-alkynylaryl isocyanides and organic dichalcogenides such as diselenides or
ditellurides was irradiated with light of wavelength over 300 or 400 nm, the intramolecular cyclization of
the isocyanides took place to afford the corresponding 2,4-bischalcogenated quinolines selectively. The
photochemical cyclization of 2-(phenylethynyl)phenyl isocyanide could also proceed in the presence of
hydrogen transfer reagents such as tris(trimethylsilyl)silane, tributylgermyl hydride, alkanethiols, and
benzeneselenol, providing the corresponding 3-phenylquinoline as the result of 2,4-dihydrogenation.
groups. Because a lot of these radical addition reactions proceed
Introduction
under photoirradiation conditions, the development of novel pho-
N-Heterocyclic compounds such as quinoline derivatives are
tochemical synthetic procedures for chalcogenated N-heterocycles
included in numerous natural products and bioactive compounds,
can be anticipated.
and therefore, the development of new methods for the preparation
Herein, we wish to report a novel photochemical intramolecular
of N-heterocycles as a key structure is of great importance
cyclization of o-alkynylaryl isocyanides in the presence of organic
in pharmaceutical and medicinal chemistry as well as organic
dichalcogenides such as diselenides and ditellurides, leading to 2,4-
synthesis.1,2 Intramolecular cyclization involving radical species
bischalcogenated quinolines selectively (Scheme 1). In addition,
as a key intermediate is one of the efficient methods for the
the photochemical reaction in the presence of hydrogen sources,
synthesis of many heterocyclic motifs.3 Since the first example
e.g., tris(trimethylsilyl)silane, tributylgermyl hydride, alkanethiols,
of the intramolecular radical cyclization reaction of isocyanides
and benzeneselenol, can access the 2,4-dihydrogenated quinolines
bearing an unsaturated bond was reported in 1994, the synthetic
smoothly.
applications of the isocyanides to form N-heterocycles have been
developed not only by radical methods,4 but also by transition
metal-catalyzed methods5 and nucleophilic cyclization methods6
in last two decades. In particular, the intramolecular radical cy-
clization of isocyanides having an unsaturated bond was employed
for the preparation of indole or pyrrole derivatives mainly, and
examples of quinoline synthesis under radical conditions are still
limited.7
Heterocycles containing chalcogen atoms have gained roles
in the fields of pharmacology, materials science, and organic
synthesis, based on the recent clarification of the characteristic
features of chalcogen compounds.8 For example, it has been
revealed that organochalcogen compounds show antioxidant, an-
Scheme 1 Photochemical cyclization of isocyanide 1.
titumor, antimicrobial, and antiviral properties.9 In a recent study,
a series of radical addition reactions of organic chalcogenides
such as disulfides, diselenides, and ditellurides to unsaturated
bonds such as acetylenes,10 allenes,11 conjugated dienes,12 alkenes,13
Results and discussion
and isocyanides14 have been advanced by our and other research
We first examined the photochemical reaction of 2-
(phenylethynyl)phenyl isocyanide (1a) with diphenyl dichalco-
Department of Applied Chemistry, Graduate School of Engineering,
Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-
8531, Japan. E-mail: ogawa@chem.osakafu-u.ac.jp; Fax: +81-72-254-9290;
Tel: +81-72-254-9290
† This paper is dedicated to the memory of the passing Professor Athel
Beckwith, prominent free radical chemist.‡
genides, such as diphenyl disulfide (2a), diphenyl diselenide (4a),
and diphenyl ditelluride (6a) (Table 1). When isocyanide 1a was
treated with diphenyl disulfide (2a) with photoirradiation, the
desired cyclic product 3a was not obtained at all (the starting
materials were recovered unchanged) (entry 1). In contrast, the
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Table 1 Photochemical reaction of isocyanide 1a with organic
Table 2 Photochemical reaction of isocyanides 1 with organic diselenides
dichalcogenidesa
4a
Entry
Y
Product
Yield (%)b
Entry
1
R1
4
R3
Product Yield (%)b
1
2
3
4
S (2a, 2 equiv.)
3a
5a
5a
5a
7a
7a
7a
7a
0
1
2
3
4
5
6
7
8
9
1a C6H5
4a
4a
4a
4a
4a
4a
C6H5
5a
5b
5c
5d
5e
5f
5g
5h
5i
65
72
70
69
62
71
82
9
Se (4a, 1 equiv.)
Se (4a, 2 equiv.)
Se (4a, 3 equiv.)
Te (6a, 1 equiv.)
Te (6a, 2 equiv.)
Te (6a, 5 equiv.)
Te (6a, 2 equiv.)
46
65
72
34
48
68
(65)
1b 4-Me-C6H4
1c 4-MeO-C6H4
1d 4-Cl-C6H4
1e 4-F-C6H4
5c
6c
7c
8c,d
1f
nBu
1g 1-cyclohexenyl 4a
1h TMS
1a
4a
4b
a Reaction conditions: isocyanide (1a, 0.10 mmol), diphenyl dichalco-
genides, CDCl3 (0.5 mL), room temperature, 4 h, hu (>300 nm: irradiation
with a high pressure Hg lamp through Pyrex). b Isolated yield. c hu
(>400 nm: irradiation with a high pressure Hg lamp through a glass filter).
d The reaction time was 14 h. The value in parenthesis was determined by
1H NMR.
4-Me-
C6H4
4-MeO-
C6H4
4-Cl-C6H4 5k
4-F-C6H4
Bn
72
10
1a
4c
5j
77
11
12
13
1a
1a
1a
4d
4e
4f
65
69
<10
51
5m
a Reaction conditions: isocyanide (1, 0.10 mmol), organic diselenide (4,
0.20 mmol), CDCl3 (0.5 mL), room temperature, 4 h, hu (>300 nm:
irradiation with a high pressure Hg lamp through Pyrex). b Isolated yield.
photochemical reaction of 1a with 1 equivalent of diphenyl
diselenide (4a) afforded the 2,4-bisselenated quinoline 5a in 46%
yield (entry 2). In the reaction mixture, the oligomer of 1a and
a small amount of unreacted 1a were obtained. The yield of 5a
successfully increased with the amount of (PhSe)2 (entries 3 and
4).15 Furthermore, diphenyl ditelluride (6a) could also be employed
for the photochemical cyclization, leading to the corresponding
2,4-bistellurated quinoline 7a in 34% yield (entry 5).16 In the case
of ditelluride 6a, increasing the amount of 6a also provided 7a
in good yields, because the excess amounts of ditelluride might
contribute to the efficiency in the abstraction of the telluro group
by the carbon radical intermediate (entries 6 and 7). Prolonging
the reaction time also increased the yield of 7a (entry 8). When
the reactions of 1a with 4a or 6a were performed in the dark,
no cyclization reaction took place. These results indicate that the
intramolecular cyclization reactions of o-alkynylaryl isocyanides
with diselenides and ditellurides require the photoirradiation.
We next examined the scope and limitations of this photo-
chemical cyclization with organic dichalcogenides using several
isocyanides 1. The results of the reaction of 1 with organic dise-
lenides 4 are summarized in Table 2. Isocyanides bearing methyl,
methoxy, chloro, and fluoro substituents on the arylethynyl groups
underwent the photochemical intramolecular cyclization success-
fully, affording the corresponding 2,4-bisselenated quinolines 5b,
5c, 5d, and 5e, respectively, in good yields (entries 2–5). Isocyanide
1f having 1-hexynyl group could also undergo the photochemical
cyclization to give 5f (entry 6). A 1-cyclohexenyl group being
conjugated with ethynyl group was tolerant of these conditions
to produce 5g in high yield (entry 7). However, isocyanide 1h
containing a TMS group gave a low yield of the cyclization
product 5h, probably because of the bulkiness of the TMS group
(entry 8). Similar conditions could be employed with several
diaryl diselenides 4b, 4c, 4d, and 4e, leading to the corresponding
quinolines 5i, 5j, 5k, and 5l in good yields (entries 9–12). When
dibenzyl diselenide (4f) was used for this photochemical reaction,
the corresponding quinoline 5m was obtained in lower yield
(entry 13). This is most probably due to the lower carbon radical
capturing ability of aliphatic diselenides compared with aromatic
ones.
Conclusive determination of the structure of the photochem-
ical cyclization product was unambiguously ascertained through
X-ray crystal analysis (Fig. 1). Thus, the formation of the quinoline
structure in the photochemical cyclization of isocyanides 1 with
organic dichalcogenides was clearly confirmed.
Fig. 1 ORTEP diagram of 5k. H atoms were omitted.
The photochemical reaction of isocyanides 1 with organic ditel-
luride 6 was also examined (Table 3).17 When isocyanides having
methyl, methoxy, and chloro substituents at the p-position were
treated with (PhTe)2 with photoirradiation, the corresponding
quinolines 7b, 7c, and 7d were obtained in moderate yields (entries
2–4).18 The photochemical reactions of 1f and 1g containing n-
butyl and 1-cyclohexenyl groups took place smoothly, forming
the corresponding 2,4-bistellurated quinolines 7f and 7g in good
yields, respectively (entries 5 and 6). Unfortunately, isocyanides 1i
and 1j having powerful electron-withdrawing groups produced 7i
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Table 3 Photochemical reaction of isocyanides 1 with organic ditellurides
6a
Entry
1
R1
R2
6
R3
7
Yield (%)b
1
2
3
4
5
6
7
8
1a C6H5
H
H
H
H
H
H
H
H
H
6a C6H5
7a
7b
7c
7d
7f
7g
7i
7j
7k
71
7m 61
7n
48
40
49
50
82
68
32
26
42
63
1b 4-Me-C6H4
1c 4-MeO-C6H4
1d 4-Cl-C6H4
6a
6a
6a
6a
6a
6a
6a
6a
1f
1g 1-cyclohexenyl
nBu
Scheme
2
Photochemical reactions of isocyanide 1a. cHexSH
=
cyclohexanethiol.
1i
1j
4-O2N-C6H4
4-NC-C6H4
9
1k Bn
ethanethiol and benzeneselenol gave 8a with excellent selectivity.22
The photochemical reaction of isocyanide 1a with benzenethiol
was also carried out; however, the reaction gave 3-phenylquinoline
(8a) and 2-phenylsulfanyl-3-phenylquinoline (9a) in 46% and
41% yields, respectively (Scheme 3). The selective syntheses of 2-
substituted quinolines by the reaction of o-alkynylaryl isocyanides
with nucleophiles were reported in ref. 6a, 6c, 6e and 6f. Thus, the
generation of 2-sulfanylquinoline may include the nucleophilic
addition of the thiolate anion to the isocyano groups due to the
higher acidity of arenethiols compared with alkanethiols. Then,
the reaction of 1a with benzenethiol in the presence of triethy-
lamine in the dark provided the corresponding 2-sulfanylquinoline
9a in 78% yield (for 2-sulfanylquinoline synthesis by this method,
see the ESI‡).23
10
11
12
1l
C6H5
Me 6a
F
H
1m C6H5
6a
1a
6b 4-MeO-
40
C6H4
13
14
1a
1a
H
H
6c 4-F-C6H4 7o
66
(23)
6d nBu
7p
a Reaction conditions: isocyanide (1, 0.10 mmol), organic ditelluride (6,
0.20 mmol), CDCl3 (0.5 mL), room temperature, 4 h, hu (>400 nm:
irradiation with a high pressure Hg lamp through a glass filter). b Isolated
yield. Value in parenthesis was determined by 1H NMR.
and 7j in low yields, due to the competing oligomerization of the
isocyanides (entries 7 and 8). In the case of 1k having a benzyl
unit, the corresponding quinoline 7k was obtained in 42% yield
(entry 9). At the same time, the formation of an oligomer of 1k
was observed. p-Substituted aromatic isocyanides 1l and 1m could
also afford the corresponding 2,4-bistellurated quinolines 7l and
7m in good yields (entries 10 and 11). Similar conditions could
be employed with several organic ditellurides 6b and 6c, forming
7n and 7o (entries 12 and 13). When isocyanide 1a was treated
with dibutyl ditelluride (6d) with photoirradiation, the formation
of 7p was observed; however, 7p could not be isolated because of
its instability (entry 14).
In this photochemical intramolecular cyclization, some reac-
tion pathways are considered. A possible pathway involves the
following: (i) the formation of chalcogen-centered radicals upon
photoirradiation; (ii) the addition of the generated radicals to
isocyano or alkynyl groups; (iii) the intramolecular cyclization
and the subsequent trapping with dichalcogenides to give the
corresponding quinolines. However, radical cyclization prefers the
5-exo cyclization to give indoles not quinolines.19 Alternatively, a
related theoretical study reported that the aza-Bergman cyclization
of the (Z)-enyne isocyanide system is possible.20 Therefore, another
possible pathway may include the photochemical aza-Bergman
cyclization of 1 to form the corresponding biradical species (see,
A in Scheme 4).
To get insight into the reaction pathway for this cyclization,
we examined the photochemical reaction of isocyanide 1a in the
presence of efficient hydrogen transfer reagents (Scheme 2). Upon
photoirradiation of isocyanide 1a in the presence of cyclohex-
anethiol, intramolecular cyclization via hydrogen abstraction took
place, affording 3-phenylquinoline (8a) in 82% yield.21 Similarly,
photochemical reaction in the presence of phenylmethanethiol,
Scheme 3 The reaction of isocyanide 1a with benzenethiol.
In addition, tributylgermyl hydride and tris(trimethylsilyl)silane
could also provide 8a in 61% and 53% yields, respectively.24,25
If the photochemical cyclization using hydrogen transfer
reagents involves the radical cyclization process via the addition
of heteroatom-centered radicals to an unsaturated bond, 2- or 4-
heteroatom substituted quinolines should be formed. In addition,
the UV-visible spectrum of 1 indicates that its absorption reaches
500 nm (see the ESI‡). Therefore, these results strongly suggest
that a photochemical aza-Bergman cyclization takes place to form
the corresponding biradical species, which abstract hydrogen from
E-H species.
A plausible reaction pathway for the photochemical intramolec-
ular cyclization of isocyanides 1 in the presence of organic
dichalcogenides or hydrogen sources is shown in Scheme 4. Upon
photoirradiation with light of wavelength over 300 nm (or 400 nm),
aza-Bergman cyclization of 1 proceeds, forming 2,4-biradical
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1b (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
1
and recycle GPC (CHCl3). Pale yellow oil; H NMR (300 MHz,
CDCl3, ppm) d 2.44 (s, 3H), 7.00–7.12 (m, 5H), 7.16 (d, J =
8.3 Hz, 2H), 7.24 (d, J = 8.3 Hz, 2H), 7.33–7.42 (m, 4H), 7.54
(m, 1H), 7.64–7.74 (m, 3H), 8.27 (d, J = 8.4 Hz, 1H); 13C NMR
(100 MHz, CDCl3, ppm) d 21.6, 126.4, 126.4, 127.9, 128.3, 128.8,
129.0, 129.0, 129.1, 129.1, 129.4, 129.6, 130.6, 132.3, 135.9, 136.3,
138.5, 138.5, 141.0, 141.3, 148.3, 158.5; IR (NaCl, cm-1) 3057,
3030, 2999, 2833, 1576, 1545, 1508, 1474, 1456, 1437, 1373, 1339,
1313, 1286, 1136, 1090, 1072, 1020, 814, 760, 735, 723, 689;
HRMS (FAB) calcd for C28H22NSe2 [M+H]+ 532.0083, found
532.0088.
Scheme 4 A plausible reaction pathway for the photochemical cyclization
of isocyanide 1.
3-(4-Methoxyphenyl)-2,4-bis(phenylselanyl)quinoline
(5c).
Quinoline 5c (38.1 mg, 0.070 mmol, 70%) was obtained from
1c (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
species A. The following abstraction of organic chalcogen groups26
or hydrogen produces the corresponding quinolines 5, 7, and 8.
1
and recycle GPC (CHCl3). Pale yellow oil; H NMR (400 MHz,
Conclusions
CDCl3, ppm) d 3.87 (s, 3H), 6.93 (d, J = 8.7 Hz, 2H), 7.00–7.10
(m, 5H), 7.17 (d, J = 8.7 Hz, 2H), 7.34–7.40 (m, 4H), 7.53 (ddd,
J = 1.4, 6.8, 8.7 Hz, 1H), 7.65–7.72 (m, 3H), 8.27 (dd, J = 0.9,
8.7 Hz, 1H); 13C NMR (75 MHz, CDCl3, ppm) d 55.2, 113.7,
126.4, 126.5, 128.1, 128.3, 128.8, 129.0, 129.0, 129.1, 129.2, 129.4,
130.7, 131.1, 136.3, 139.0, 144.5, 144.7, 147.0, 148.3, 157.1, 159.8;
IR (NaCl, cm-1) 3057, 3000, 2958, 2928, 2833, 1608, 1576, 1547,
1508, 1475, 1437, 1375, 1339, 1313, 1285, 1248, 1175, 1136, 1092,
1034, 1022, 999, 885, 829, 760, 737, 689; HRMS (FAB) calcd for
C28H22NOSe2 [M+H]+ 548.0032, found 548.0026.
In summary, we have described a novel photochemical cyclization
of o-alkynylaryl isocyanides 1 in the presence of organic
dichalcogenides. The reaction can access the corresponding
2,4-dichalcogenated quinolines selectively. This photochemical
cyclization can be applied to the synthesis of 3-substituted
quinolines by the reaction of isocyanides 1 with hydrogen transfer
reagents such as hydrosilane, germyl hydride, thiols, and selenol.
Further studies on the synthetic application of this system are
now in progress.
3-(4-Chlorophenyl)-2,4-bis(phenylselanyl)quinoline
(5d).
Experiment
Quinoline 5d (37.8 mg, 0.069 mmol, 69%) was obtained from
1d (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Slightly yellow oil; 1H NMR (400
MHz, CDCl3, ppm) d 6.97–7.02 (m, 2H), 7.03–7.16 (m, 5H),
7.31–7.45 (m, 6H), 7.57 (ddd, J = 1.4, 6.8, 8.2 Hz, 1H), 7.62–7.66
(m, 2H), 7.72 (d, J = 8.2 Hz, 1H), 8.33 (d, J = 8.2 Hz, 1H);
13C NMR (75 MHz, CDCl3, ppm) d 126.6, 126.7, 128.1, 128.4,
128.5, 128.8, 128.9, 129.1, 129.2, 129.8, 131.0, 131.3, 131.9, 134.6,
136.3, 137.1, 139.2, 139.7, 148.4, 157.9; IR (NaCl, cm-1) 3058,
3029, 1541, 1506, 1489, 1474, 1437, 1373, 1338, 1313, 1286, 1136,
1094, 1072, 1016, 883, 826, 760, 735, 689; HRMS (FAB) calcd for
C27H19ClNSe2 [M+H]+ 551.9536, found 551.9533.
General procedure for the photochemical intramolecular cycliza-
tion of o-alkynylaryl isocyanide with organic diselenide
In a NMR tube (f = 5 mm, length = 180 mm) were placed 2-
(phenylethynyl)phenyl isocyanide (1a, 20 mg, 0.10 mmol) and
diphenyl diselenide (4a, 62 mg, 0.20 mmol) in CDCl3 (0.5 mL)
under ambient atmosphere, and the mixture was irradiated with a
high pressure Hg lamp through Pyrex (hn > 300 nm) for 4 h. After
the photoirradiation, the resulting mixture was concentrated in
vacuo, and the purification by preparative TLC (PTLC) on silica
gel (hexane (Hex) : AcOEt = 9 : 1) and recycle GPC (CHCl3) gave 3-
phenyl-2,4-bis(phenylselanyl)quinoline (5a, 33.4 mg, 0.065 mmol,
65%) as a slightly yellow solid (mp 129–130 ◦C).
3-(4-Fluorophenyl)-2,4-bis(phenylselanyl)quinoline
(5e).
3-Phenyl-2,4-bis(phenylselanyl)quinoline (5a). Slightly yellow
Quinoline 5e (32.8 mg, 0.062 mmol, 62%) was obtained from
1e (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
◦
1
solid; mp 129–130 C (crystalized from acetone); H NMR (400
MHz, CDCl3, ppm) d 6.99–7.12 (m, 5H), 7.22–7.27 (m, 2H), 7.34–
7.48 (m, 7H), 7.55 (ddd, J = 1.4, 6.8, 8.4 Hz, 1H), 7.64–7.69 (m,
2H), 7.71 (dd, J = 1.4, 8.4 Hz, 1H), 8.30 (dd, J = 1.4, 8.4 Hz, 1H);
13C NMR (100 MHz, CDCl3, ppm) d 126.5, 126.5, 128.0, 128.3,
128.3, 128.6, 128.8, 129.0, 129.1, 129.1, 129.5, 129.9, 130.7, 132.2,
136.3, 138.7, 138.8, 141.1, 141.1, 148.3, 158.2; IR (NaCl, cm-1)
3055, 3030, 1576, 1541, 1506, 1489, 1474, 1456, 1437, 1372, 1339,
1313, 1286, 1136, 1092, 1072, 1020, 881, 762, 737, 689; HRMS
(FAB) calcd for C27H20NSe2 [M+H]+ 517.9926, found 517.9932.
◦
and recycle GPC (CHCl3). Slightly yellow solid; mp 140–141 C
(crystalized from acetone); 1H NMR (300 MHz, CDCl3, ppm) d
6.97–7.13 (m, 7H), 7.14–7.21 (m, 2H), 7.34–7.45 (m, 4H), 7.57
(ddd, J = 1.4, 7.0, 8.3 Hz, 1H), 7.62–7.68 (m, 2H), 7.72 (dd, J =
1.4, 8.3 Hz, 1H), 8.34 (dd, J = 1.4, 8.3 Hz, 1H); 13C NMR (100
MHz, CDCl3, ppm) d 115.3 (d, JC-F = 21.0 Hz), 126.6, 126.7,
128.1, 128.4, 128.8, 128.9, 128.9, 129.1, 129.1, 129.7, 130.9, 131.7
(d, JC-F = 8.6 Hz), 131.9, 134.6 (d, JC-F = 3.8 Hz), 136.2, 139.3,
139.9, 148.3, 158.3, 162.8 (d, JC-F = 246.9 Hz); IR (NaCl, cm-1)
3072, 3030, 1541, 1506, 1489, 1474, 1456, 1437, 1371, 1339, 1313,
3-(4-Methylphenyl)-2,4-bis(phenylselanyl)quinoline
(5b).
Quinoline 5b (38.1 mg, 0.072 mmol, 72%) was obtained from
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1221, 1158, 1136, 1092, 1013, 881, 772, 737, 689; HRMS (FAB)
calcd for C27H19FNSe2 [M+H]+ 535.9832, found 535.9838.
1H), 8.36 (d, J = 7.8 Hz, 1H); 13C NMR (75 MHz, CDCl3, ppm)
d 55.2, 55.3, 114.6, 114.9, 119.6, 122.0, 126.2, 128.1, 128.2, 128.5,
128.9, 129.1, 129.3, 130.1, 133.4, 138.0, 138.9, 139.5, 140.4, 148.4,
158.8, 158.9, 160.0; IR (NaCl, cm-1) 3059, 3002, 2930, 2902,
2835, 1589, 1574, 1549, 1489, 1475, 1460, 1441, 1373, 1339, 1286,
1246, 1173, 1136, 1092, 1074, 1030, 1005, 881, 822, 760, 721, 698;
HRMS (FAB) calcd for C29H24NO2Se2 [M+H]+ 578.0137, found
578.0142.
3-n-Butyl-2,4-bis(phenylselanyl)quinoline (5f). Quinoline 5f
(35.0 mg, 0.071 mmol, 71%) was obtained from 1f (0.10 mmol)
according to the general procedure. The crude mixture was purified
by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle GPC
1
(CHCl3). Pale yellow oil; H NMR (400 MHz, CDCl3, ppm) d
0.98 (t, J = 7.3 Hz, 3H), 1.51 (sextet, J = 7.3 Hz, 2H), 1.59–1.70
(m, 2H), 3.23 (t, J = 8.2 Hz, 2H), 7.12 (s, 5H), 7.35 (t, J = 7.6 Hz,
1H), 7.38–7.43 (m, 2H), 7.48 (t, J = 7.6 Hz, 1H), 7.65 (d, J = 8.2 Hz,
1H), 7.70–7.76 (m, 2H), 8.26 (d, J = 8.2 Hz, 1H); 13C NMR (100
MHz, CDCl3, ppm) d 13.8, 23.1, 32.6, 35.8, 126.3, 126.5, 128.4,
128.4, 128.7, 128.8, 128.8, 128.9, 129.3, 129.6, 132.2, 136.2, 137.8,
141.0, 141.0, 147.5, 158.0; IR (NaCl, cm-1) 3057, 3028, 2955, 2928,
2858, 1578, 1543, 1522, 1508, 1476, 1458, 1437, 1373, 1354, 1296,
1275, 1180, 1140, 1067, 1032, 1020, 999, 907, 760, 735, 689; HRMS
(FAB) calcd for C25H24NSe2 [M+H]+ 498.0239, found 498.0231.
3-Phenyl-2,4-bis(4-chlorophenylselanyl)quinoline (5k). Quino-
line 5k (37.8 mg, 0.065 mmol, 65%) was obtained from 1a
(0.10 mmol) according to the general procedure. The crude mixture
was purified by PTLC on silica gel (Hex : AcOEt = 9◦: 1) and recycle
GPC (CHCl3). Slightly yellow solid; mp 145–146 C (crystalized
from acetone); 1H NMR (400 MHz, CDCl3, ppm) d 6.92 (d, J =
8.2 Hz, 2H), 7.02 (d, J = 8.2 Hz, 2H), 7.19–7.23 (m, 2H), 7.34 (d,
J = 8.7 Hz, 2H), 7.39–7.51 (m, 4H), 7.55–7.62 (m, 3H), 7.74 (d,
J = 8.2 Hz, 1H), 8.27 (d, J = 8.2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) d 126.7, 127.0, 127.8, 128.3, 128.7, 129.0, 129.1,
129.2, 129.3, 129.7, 130.1, 132.1, 132.7, 133.2, 134.7, 137.6, 138.3,
138.5, 140.7, 148.2, 157.8; IR (NaCl, cm-1) 3058, 3029, 1543, 1508,
1489, 1474, 1458, 1387, 1375, 1339, 1313, 1286, 1219, 1136, 1088,
1070, 1030, 1011, 881, 810, 760, 729, 698; HRMS (FAB) calcd for
C27H18Cl2NSe2 [M+H]+ 585.9147, found 585.9137.
3-(1-Cyclohexenyl)-2,4-bis(phenylselanyl)quinoline
(5g).
Quinoline 5g (42.6 mg, 0.082 mmol, 82%) was obtained from
1g (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 1.71–1.80 (m, 2H), 1.81–1.92 (m, 2H), 2.11–2.24
(m, 2H), 2.42–2.52 (m, 2H), 5.63 (s, 1H), 7.09–7.21 (m, 5H),
7.31 (t, J = 7.5 Hz, 1H), 7.37–7.43 (m, 2H), 7.48 (t, J = 7.5 Hz,
1H), 7.66 (d, J = 7.9 Hz, 1H), 7.71–7.78 (m, 2H), 8.16 (d, J =
8.3 Hz, 1H); 13C NMR (100 MHz, CDCl3, ppm) d 21.7, 23.0,
25.5, 28.5, 126.1, 126.3, 127.8, 128.2, 128.4, 128.8, 128.9, 129.1,
129.2, 129.5, 130.0, 130.2, 131.6, 133.0, 136.1, 136.6, 142.9, 148.1,
158.0; IR (NaCl, cm-1) 3057, 3028, 2930, 2855, 2829, 1578, 1541,
1521, 1508, 1475, 1437, 1375, 1339, 1304, 1285, 1136, 1070, 1043,
1020, 999, 881, 760, 735, 689; HRMS (FAB) calcd for C27H24NSe2
[M+H]+ 522.0239, found 522.0248.
3-Phenyl-2,4-bis(4-fluorophenylselanyl)quinoline (5l). Quino-
line 5l (37.8 mg, 0.069 mmol, 69%) was obtained from 1a
(0.10 mmol) according to the general procedure. The crude mixture
was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle
GPC (CHCl3). Pale yellow solid; mp 112–113 ◦C (crystalized from
acetone); 1H NMR (400 MHz, CDCl3, ppm) d 6.76 (t, J = 8.7 Hz,
2H), 6.99 (dd, J = 5.5, 8.7 Hz, 2H), 7.07 (t, J = 8.7 Hz, 2H),
7.18–7.23 (m, 2H), 7.38–7.48 (m, 4H), 7.54–7.64 (m, 3H), 7.70 (d,
J = 8.2 Hz, 1H), 8.32 (d, J = 8.2 Hz, 1H); 13C NMR (100 MHz,
CDCl3, ppm) d 116.1 (d, JC-F = 21.9 Hz), 116.3 (d, JC-F = 21.9 Hz),
123.6, 126.2 (d, JC-F = 3.8 Hz), 126.5, 126.8 (d, JC-F = 3.8 Hz),
128.3, 128.7, 128.7, 129.1, 129.7, 129.9, 133.3 (d, JC-F = 8.6 Hz),
138.4 (d, JC-F = 8.6 Hz), 139.1, 140.2, 140.4, 148.2, 158.1, 161.9 (d,
JC-F = 246.9 Hz), 163.1 (d, JC-F = 246.9 Hz); IR (NaCl, cm-1) 3058,
3030, 1583, 1549, 1485, 1373, 1339, 1313, 1286, 1227, 1157, 1136,
1090, 1069, 1013, 881, 824, 760, 721, 698; HRMS (FAB) calcd for
C27H18F2NSe2 [M+H]+ 553.9738, found 553.9732.
3-Phenyl-2,4-bis(4-methylphenylselanyl)quinoline (5i). Quino-
line 5i (39.1 mg, 0.072 mmol, 72%) was obtained from 1a
(0.10 mmol) according to the general procedure. The crude mixture
was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle
GPC (CHCl3). Pale yellow solid; mp 124–126 ◦C (crystalized from
acetone); 1H NMR (400 MHz, CDCl3, ppm) d 2.23 (s, 3H), 2.40
(s, 3H), 6.87 (d, J = 8.2 Hz, 2H), 6.92 (d, J = 8.2 Hz, 2H), 7.18 (d,
J = 7.8 Hz, 2H), 7.35–7.46 (m, 5H), 7.51–7.57 (m, 3H), 7.66–7.70
(m, 1H), 7.72 (dd, J = 0.9, 8.7 Hz, 1H), 8.30 (dd, J = 0.9, 8.7 Hz,
1H); 13C NMR (100 MHz, CDCl3, ppm) d 21.0, 21.4, 125.1, 125.4,
126.3, 128.2, 128.4, 128.5, 129.0, 129.1, 129.3, 129.7, 129.9, 130.9,
131.8, 132.5, 136.2, 138.3, 138.8, 138.9, 140.8, 148.3, 158.4; IR
(NaCl, cm-1) 3055, 3020, 2919, 2862, 1541, 1506, 1489, 1474,
1443, 1373, 1339, 1313, 1286, 1136, 1092, 1070, 1015, 800, 756,
721, 698; HRMS (FAB) calcd for C29H24NSe2 [M+H]+ 546.0239,
found 546.0236.
General procedure for the photochemical intramolecular cycliza-
tion of o-alkynylaryl isocyanide with organic ditelluride
In a NMR tube (f = 5 mm, length = 180 mm) were placed 2-
(phenylethynyl)phenyl isocyanide (1a, 20 mg, 0.10 mmol) and
diphenyl ditelluride (6a, 82 mg, 0.20 mmol) in CDCl3 (0.5 mL)
under ambient atmosphere, and the mixture was irradiated with
a high pressure Hg lamp through a glass filter (hn > 400 nm)
for 4 h. After the photoirradiation, the resulting mixture was
concentrated in vacuo, and the purification by PTLC on silica
gel (Hex : AcOEt = 9 : 1) and recycle GPC (CHCl3) gave 3-phenyl-
2,4-bis(phenyltellanyl)phenylquinoline (7a, 29.3 mg, 0.048 mmol,
48%) as a yellow oil.
3-Phenyl-2,4-bis(4-methoxyphenylselanyl)quinoline
(5j).
Quinoline 5j (44.3 mg, 0.077 mmol, 77%) was obtained from
1a (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
1
1
and recycle GPC (CHCl3). Pale yellow oil; H NMR (400 MHz,
3-Phenyl-2,4-bis(phenyltellanyl)quinoline (7a). Yellow oil; H
CDCl3, ppm) d 3.71 (s, 3H), 3.85 (s, 3H), 6.61 (d, J = 8.7 Hz, 2H),
6.91 (d, J = 8.7 Hz, 2H), 6.98 (d, J = 8.7 Hz, 2H), 7.20–7.27 (m,
2H), 7.35–7.46 (m, 4H), 7.50–7.58 (m, 3H), 7.70 (d, J = 7.8 Hz,
NMR (300 MHz, CDCl3, ppm) d 7.03 (t, J = 7.2 Hz, 2H), 7.13–
7.18 (m, 3H), 7.29–7.56 (m, 10 H), 7.70 (d, J = 8.4 Hz, 1H), 7.90
(d, J = 6.6 Hz, 2H), 8.22 (d, J = 8.4 Hz, 1H); 13C NMR (75 MHz,
3772 | Org. Biomol. Chem., 2011, 9, 3768–3775
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CDCl3, ppm) d 116.0, 118.0, 126.6, 127.5, 128.3, 128.5, 129.0,
129.2, 129.4, 129.5, 129.7, 133.4, 134.9, 135.1, 136.7, 139.8, 143.3,
147.2, 148.8, 149.0; IR (NaCl, cm-1) 3053, 1651, 1574, 1537, 1472,
1435, 1367, 1333, 1312, 1279, 1132, 1080, 1063, 1016, 997, 756,
733, 689; HRMS (EI) calcd for C27H19NTe2 [M]+ 616.9642, found
616.9635.
J = 6.6 Hz, 2H), 8.29 (d, J = 8.4 Hz, 1H); 13C NMR (75 MHz,
CDCl3, ppm) d 13.8, 23.1, 33.6, 43.7, 115.3, 116.0, 126.8, 127.4,
128.4, 128.5, 129.1, 129.3, 129.6, 129.8, 130.5, 133.8, 135.6, 140.0,
145.7, 148.0, 148.3; IR (NaCl, cm-1) 3053, 2955, 2923, 2870, 2855,
1651, 1574, 1529, 1474, 1435, 1366, 1342, 1288, 1271, 1178, 1136,
1076, 1063, 1016, 997, 901, 758, 729, 689; HRMS (FAB) calcd for
C25H24NTe2 [M+H]+ 598.0033, found 598.0034.
3-(4-Methylphenyl)-2,4-bis(phenyltellanyl)quinoline
(7b).
Quinoline 7b (25.2 mg, 0.040 mmol, 40%) was obtained from
1b (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 2.47 (s, 3H), 7.04 (t, J = 7.5 Hz, 2H), 7.13–7.25
(m, 4H), 7.31–7.42 (m, 7H), 7.53 (t, J = 7.5 Hz, 1H), 7.71 (d, J =
3-(1-Cyclohexenyl)-2,4-bis(phenyltellanyl)quinoline
(7g).
Quinoline 7g (41.9 mg, 0.068 mmol, 68%) was obtained from
1g (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 1.67–2.00 (m, 4H), 2.05–2.35 (m, 2H), 2.48–2.76
(m, 2H), 5.64 (m, 1H), 7.02–7.20 (m, 3H), 7.22–7.53 (m, 7H),
7.67 (d, J = 9.0 Hz, 1H), 7.97 (dd, J = 3.0, 9.0 Hz, 2H), 8.12 (d,
J = 9.0 Hz, 1H); 13C NMR (75 MHz, CDCl3, ppm) d 21.5, 23.1,
25.3, 28.4, 116.2, 117.8, 126.4, 126.7, 127.4, 128.2, 128.8, 129.0,
129.3, 129.4, 129.6, 132.7, 132.9, 136.1, 139.5, 139.6, 142.0, 148.7,
148.9, 148.9; IR (NaCl, cm-1) 3053, 2930, 2855, 1645, 1574, 1531,
1474, 1433, 1369, 1327, 1302, 1281, 1132, 1065, 1042, 1016, 997,
977, 920, 908, 758, 731, 691; HRMS (FAB) calcd for C27H24NTe2
[M+H]+ 622.0033, found 622.0034.
8.4 Hz, 1H), 7.91 (d, J = 6.6 Hz, 2H), 8.20 (d, J = 8.4 Hz, 1H); 13
C
NMR (75 MHz, CDCl3, ppm) d 21.6, 116.1, 118.1, 126.5, 127.4,
128.3, 128.8, 129.0, 129.1, 129.3, 129.4, 129.6, 129.8, 133.4, 136.7,
139.1, 139.8, 140.5, 146.9, 148.8, 149.3; IR (NaCl, cm-1) 3051,
3024, 2918, 2853, 1647, 1574, 1535, 1508, 1473, 1433, 1367, 1333,
1313, 1281, 1132, 1080, 1065, 1016, 997, 968, 908, 878, 816, 758,
731, 689; HRMS (FAB) calcd for C28H22NTe2 [M+H]+ 631.9877,
found 631.9885.
3-(4-Methoxyphenyl)-2,4-bis(phenyltellanyl)quinoline
(7c).
Quinoline 7c (31.4 mg, 0.049 mmol, 49%) was obtained from
1c (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 3.90 (s, 3H), 6.93 (d, J = 8.7 Hz, 2H), 7.04 (t, J =
7.2 Hz, 2H), 7.01–7.17 (m, 3H), 7.26–7.40 (m, 6H), 7.53 (t, J =
6.9 Hz, 1H), 7.70 (d, J = 8.4 Hz, 1H), 7.91 (d, J = 8.1 Hz, 2H),
8.19 (d, J = 7.8 Hz, 1H); 13C NMR (75 MHz, CDCl3, ppm) d 55.3,
113.9, 116.1, 118.5, 126.5, 127.5, 128.3, 129.0, 129.1, 129.4, 129.8,
131.1, 132.3, 133.3, 135.8, 136.7, 136.9, 139.8, 146.9, 148.7, 149.9,
160.1; IR (NaCl, cm-1) 3055, 2926, 2837, 1645, 1607, 1574, 1510,
1474, 1435, 1331, 1292, 1250, 1177, 1032, 833, 737, 689; HRMS
(FAB) calcd for C28H22NOTe2 [M+H]+ 647.9826, found 647.9820.
3-(4-Nitorophenyl)-2,4-bis(phenyltellanyl)quinoline
(7i).
Quinoline 7i (21.2 mg, 0.032 mmol, 32%) was obtained
from 1i (0.10 mmol) according to the general procedure. The
crude mixture was purified by PTLC on silica gel (Hex : AcOEt =
9 : 1) and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 7.03 (t, J = 7.5 Hz, 2H), 7.18–7.24 (m, 3H),
7.28–7.35 (m, 4H), 7.40 (d, J = 7.5 Hz, 1H), 7.48 (t, J = 7.8 Hz,
1H), 7.63 (t, J = 7.8 Hz, 1H), 7.75 (d, J = 8.7 Hz, 1H), 7.85 (d, J =
8.1 Hz, 2H), 8.15 (d, J = 8.4 Hz, 2H), 8.32 (d, J = 8.1 Hz, 1H);
13C NMR (75 MHz, CDCl3, ppm) d 115.4, 117.2, 123.5, 127.2,
128.0, 128.6, 129.2, 129.5, 129.6, 129.7, 129.9, 130.0, 131.1, 133.2,
137.1, 139.9, 144.9, 145.3, 147.8, 148.8, 149.1; IR (NaCl, cm-1)
3055, 1597, 1520, 1474, 1435, 1345, 1312, 1277, 1080, 1016, 851,
758, 730, 691; HRMS (FAB) calcd for C27H19N2O2Te2 [M+H]+
662.9571, found 662.9579.
3-(4-Chlorophenyl)-2,4-bis(phenyltellanyl)quinoline
(7d).
Quinoline 7d (32.2 mg, 0.050 mmol, 50%) was obtained from
1d (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 7.03 (t, J = 7.8 Hz, 2H), 7.09–7.19 (m, 3H),
7.25–7.41 (m, 8H), 7.55 (t, J = 8.4 Hz, 1H), 7.70 (d, J = 8.4 Hz,
1H), 7.88 (d, J = 8.1 Hz, 2H), 8.25 (d, J = 8.4 Hz, 1H); 13C NMR
(75 MHz, CDCl3, ppm) d 115.7, 117.7, 126.8, 127.6, 128.4, 128.7,
129.1, 129.4, 129.5, 129.8, 130.0, 131.2, 133.3, 135.0, 136.9, 139.8,
141.3, 146.0, 148.7, 148.8; IR (NaCl, cm-1) 3055, 1645, 1574, 1531,
1489, 1474, 1435, 1394, 1367, 1333, 1281, 1217, 1092, 1016, 997,
878, 827, 756, 735, 689; HRMS (FAB) calcd for C27H19ClNTe2
[M+H]+ 651.9331, found 651.9338.
3-(4-Cyanophenyl)-2,4-bis(phenyltellanyl)quinoline
(7j).
Quinoline 7j (16.8 mg, 0.026 mmol, 26%) was obtained
from 1j (0.10 mmol) according to the general procedure. The
crude mixture was purified by PTLC on silica gel (Hex : AcOEt =
9 : 1) and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 7.04 (t, J = 6.0 Hz, 2H), 7.17–7.24 (m, 4H),
7.30–7.49 (m, 5H), 7.59–7.64 (m, 3H), 7.74 (d, J = 7.5 Hz, 1H),
7.85 (d, J = 6.6 Hz, 2H), 8.31 (d, J = 7.5 Hz, 1H); 13C NMR (100
MHz, CDCl3) d 109.8, 115.5, 117.3, 118.0, 127.2, 127.9, 128.2,
128.6, 129.2, 129.5, 129.6, 130.0, 130.8, 131.7, 132.1, 133.3, 137.1,
139.9, 146.0, 147.3, 149.5, 149.9; IR (NaCl, cm-1) 3053, 2228,
1647, 1474, 1435, 1016, 997, 910, 835, 758, 735, 691; HRMS
(FAB) calcd for C28H19N2Te2 [M+H]+ 642.9673, found 642.9682.
3-n-Butyl-2,4-bis(phenyltellanyl)quinoline (7f). Quinoline 7f
(48.6 mg, 0.082 mmol, 82%) was obtained from 1f (0.10 mmol)
according to the general procedure. The crude mixture was purified
by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle GPC
3-Phenylmethyl-2,4-bis(phenyltellanyl)quinoline (7k). Quino-
line 7k (26.2 mg, 0.042 mmol, 42%) was obtained from 1k
(0.10 mmol) according to the general procedure. The crude mixture
was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle
1
(CHCl3). Yellow oil; H NMR (300 MHz, CDCl3, ppm) d 0.99
1
(t, J = 7.5 Hz, 3H), 1.45–1.70 (m, 4H), 3.26 (t, J = 8.4 Hz, 2H),
7.07 (t, J = 7.5 Hz, 2H), 7.15 (t, J = 7.5 Hz, 1H), 7.32–7.42 (m,
6H), 7.48 (t, J = 6.9 Hz, 1H), 7.66 (d, J = 8.4 Hz, 1H), 7.98 (d,
GPC (CHCl3). Yellow oil; H NMR (300 MHz, CDCl3, ppm) d
4.84 (s, 2H), 7.02–7.41 (m, 14H), 7.52 (t, J = 8.3 Hz, 1H), 7.70
(d, J = 8.1 Hz, 1H), 7.91 (d, J = 8.1 Hz, 2H), 8.32 (d, J = 8.4 Hz,
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1H); 13C NMR (75 MHz, CDCl3, ppm) d 49.2, 115.1, 116.6, 126.5,
126.9, 127.5, 128.3, 128.6, 128.8, 128.9, 129.0, 129.4, 129.6, 130.4,
132.8, 134.1, 136.1, 138.5, 139.8, 143.3, 148.1, 149.8; IR (NaCl,
cm-1) 3053, 3026, 2976, 2878, 2821, 1643, 1574, 1547, 1528, 1493,
1472, 1452, 1433, 1366, 1342, 1286, 1168, 1132, 1123, 1063, 1016,
1008, 987, 943, 908, 876, 760, 729, 689; HRMS (FAB) calcd for
C28H22NTe2 [M+H]+ 631.9877, found 631.9881.
GPC (CHCl3). Pale yellow oil; 1H NMR (300 MHz, CDCl3, ppm)
d 6.74 (t, J = 8.7 Hz, 2H), 7.02 (t, J = 8.7 Hz, 2H), 7.20 (d, J =
6.9 Hz, 2H), 7.29 (dd, J = 5.6, 9.0 Hz, 2H), 7.39–7.50 (m, 4H),
7.56 (t, J = 8.4 Hz, 1H), 7.69 (d, J = 8.4 Hz, 1H), 7.83 (dd, J = 5.7,
8.7 Hz, 2H), 8.21 (d, J = 8.4 Hz, 1H); 13C NMR (75 MHz, CDCl3,
ppm) d 116.4 (d, JC-F = 21.0 Hz), 116.8 (d, JC-F = 21.0 Hz), 126.3,
126.7, 128.6, 128.7, 128.8, 128.8, 129.1, 129.4 (d, JC-F = 3.7 Hz),
129.7, 129.7 (d, JC-F = 3.7 Hz), 133.1, 139.3 (d, JC-F = 7.4 Hz),
139.6, 142.1 (d, JC-F = 7.4 Hz), 142.9, 146.9, 148.8, 148.9, 162.7 (d,
JC-F = 245.5 Hz), 163.2 (d, JC-F = 246.7 Hz); IR (NaCl, cm-1) 3059,
3026, 1651, 1582, 1537, 1485, 1443, 1389, 1367, 1333, 1312, 1294,
1281, 1227, 1161, 1134, 1086, 1028, 1015, 968, 876, 822, 754, 700,
667, 648; HRMS (FAB) calcd for C27H18F2NTe2 [M+H]+ 653,9532,
found 653.9529.
6-Methyl-3-phenyl-2,4-bis(phenyltellanyl)quinoline
(7l).
Quinoline 7l (39.4 mg, 0.063 mmol, 63%) was obtained
from 1l (0.10 mmol) according to the general procedure. The
crude mixture was purified by PTLC on silica gel (Hex : AcOEt =
9 : 1) and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 2.35 (s, 3H), 7.01 (t, J = 7.4 Hz, 2H), 7.13 (t, J =
7.5 Hz, 1H), 7.20 (d, J = 6.9 Hz, 2H), 7.25–7.46 (m, 9H), 7.60 (d,
J = 8.4 Hz, 1H), 7.88 (d, J = 7.8 Hz, 2H), 7.95 (s, 1H); 13C NMR
(75 MHz, CDCl3, ppm) d 21.6, 116.1, 117.9, 127.4, 128.2, 128.5,
128.6, 128.9, 129.1, 129.3, 129.6, 129.7, 131.3, 132.3, 136.4, 136.9,
139.7, 143.3, 146.9, 147.3, 147.4; IR (NaCl, cm-1) 3053, 3024,
2990, 2918, 2856, 1645, 1574, 1531, 1489, 1474, 1435, 1373, 1340,
1308, 1273, 1177, 1140, 1086, 1028, 1016, 997, 926, 908, 824,
756, 731, 698, 691; HRMS (FAB) calcd for C28H22NTe2 [M+H]+
631.9877, found 631.9871.
General procedure for the photochemical intramolecular cycliza-
tion of o-alkynylaryl isocyanide in the presence of hydrogen source,
e.g., cyclohexanethiol
In a NMR tube (f = 5 mm, length = 180 mm) were placed 2-
(phenylethynyl)phenyl isocyanide (1a, 20 mg, 0.10 mmol) and
cyclohexanethiol (23 mg, 0.20 mmol) in CDCl3 (0.5 mL) un-
der nitrogen atmosphere, and the reaction was performed for
4 h upon irradiation with a high-pressure Hg lamp through a
Pyrex (hn > 300 nm). After the photoirradiation, the resulting
mixture was concentrated in vacuo, and the purification by
PTLC (Hex : AcOEt = 9 : 1) and recycle GPC (CHCl3) gave 3-
phenylquinoline (8a, 16.8 mg, 0.082 mmol, 82%) as a colorless
oil.
6-Fluoro-3-phenyl-2,4-bis(phenyltellanyl)quinoline
(7m).
Quinoline 7m (38.5 mg, 0.061 mmol, 61%) was obtained
from 1m (0.10 mmol) according to the general procedure. The
crude mixture was purified by PTLC on silica gel (Hex : AcOEt =
9 : 1) and recycle GPC (CHCl3). Yellow oil; 1H NMR (300 MHz,
CDCl3, ppm) d 7.06 (t, J = 7.5 Hz, 2H), 7.15–7.24 (m, 3H),
7.30–7.51 (m, 9H), 7.70 (dd, J = 5.4, 8.7 Hz, 1H), 7.88 (m, 2H),
7.92 (d, J = 2.4 Hz, 1H); 13C NMR (75 MHz, CDCl3, ppm) d
117.1 (d, JC-F = 24.7 Hz), 117.8, 119.1 (d, JC-F = 25.9 Hz), 127.8,
128.4, 128.6, 128.8 (d, JC-F = 2.5 Hz), 129.0, 129.1, 129.2, 129.6
(d, JC-F = 2.5 Hz), 131.1, 131.3, 131.9, 132.0, 136.9, 139.9, 143.2,
145.9, 158.1, 160.5 (d, JC-F = 244.2 Hz); IR (NaCl, cm-1) 3055,
1622, 1574, 1553, 1533, 1481, 1435, 1342, 1306, 1200, 1169, 1082,
1016, 943, 827, 754, 731, 698, 691; Anal. Calcd. for C27H18FNTe2:
C, 51.42; H, 2.88; N, 2.22. Found: C, 51.32; H, 2.89; N, 2.51.
3-Phenylquinoline (8a)17. Colorless oil; 1H NMR (300 MHz,
CDCl3, ppm) d 7.37–7.62 (m, 4H), 7.65–7.77 (m, 3H), 7.90 (d, J =
8.4 Hz, 1H), 8.15 (d, J = 8.4 Hz, 1H), 8.32 (s, 1H), 9.20 (s, 1H); 13
C
NMR (75 MHz, CDCl3, ppm) d 127.0, 127.4, 128.0, 128.1, 128.1,
129.1, 129.2, 129.3, 133.2, 133.8, 137.9, 147.3, 149.9; IR (NaCl,
cm-1) 3030, 1653, 1558, 1541, 1493, 1448, 1418, 1362, 1339, 1026,
953, 903, 787, 762, 696; MS (EI) m/z 205 (M+, 100).
Acknowledgements
3-Phenyl-2,4-bis(4-methoxyphenyltellanyl)quinoline
(7n).
This work was supported by Grant-in-Aid for Scientific Research
on Scientific Research (B, 19350095), from the Ministry of
Education, Culture, Sports, Science and Technology, Japan, the
Priority Strategic Support Program (Tohoku University), and
Kyoto-Advanced Nanotechnology Network. We also thank Mr
Masayuki Daitou and Mr Taichi Tamai for their experimental
support. T.M. appreciates the Japan Society for the Promotion of
Science (JSPS) for the Research Fellowship for Young Scientists.
Quinoline 7n (27.1 mg, 0.040 mmol, 40%) was obtained from
1a (0.10 mmol) according to the general procedure. The crude
mixture was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1)
1
and recycle GPC (CHCl3). Pale yellow oil; H NMR (300 MHz,
CDCl3, ppm) d 3.72 (s, 3H), 3.84 (s, 3H), 6.60 (d, J = 8.8 Hz, 2H),
6.87 (d, J = 8.8 Hz, 2H), 7.20–7.26 (m, 2H), 7.29 (d, J = 8.8 Hz,
2H), 7.32–7.56 (m, 5H), 7.68 (d, J = 7.2 Hz, 1H), 7.78 (d, J =
8.8 Hz, 2H), 8.25 (d, J = 7.5 Hz, 1H); 13C NMR (75 MHz, CDCl3,
ppm) d 55.1, 55.2, 104.8, 107.7, 115.0, 115.3, 126.4, 128.5, 129.0,
129.1, 129.5, 129.8, 129.9, 133.1, 139.4, 139.7, 141.7, 143.3, 146.7,
148.1, 148.8, 159.6, 160.0; IR (NaCl, cm-1) 3057, 3003, 2959,
2937, 2835, 1645, 1585, 1531, 1489, 1472, 1460, 1441, 1398, 1367,
1333, 1285, 1246, 1177, 1134, 1080, 1065, 1028, 1003, 910, 822,
760, 731, 700; HRMS (FAB) calcd for C29H24NO2Te2 [M+H]+
677.9932, found 677.9926.
Notes and references
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line 7o (42.9 mg, 0.066 mmol, 66%) was obtained from 1a
(0.10 mmol) according to the general procedure. The crude mixture
was purified by PTLC on silica gel (Hex : AcOEt = 9 : 1) and recycle
3774 | Org. Biomol. Chem., 2011, 9, 3768–3775
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