Regiocontrolled synthesis of 2,4,6-triarylpyridines from methyl ketones, electron-deficient acetylenes and ammonium acetate

Article abstract of DOI:10.1039/d1ob00193k

A novel one-pot two-step approach for the synthesis of 2,4,6-triarylpyridinesvia t-BuOK/DMSO-promotedC-vinylation of a variety of methyl ketones with electron-deficient acetylenes (alkynones) followed by a cyclization of thein situgenerated unsaturated 1,5-dicarbonyl species with ammonium acetate has been developed. This approach possesses competitive advantages such as high regioselectivity, available starting materials and the absence of transition-metal catalysts, oxidants and undesirable byproducts. A wide synthetic utility of the developed approach was demonstrated by the synthesis of trisubstituted, tetrasubstituted and fused pyridines.

Full text of DOI:10.1039/d1ob00193k

Organic &
Biomolecular Chemistry
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Regiocontrolled synthesis of 2,4,6-triarylpyridines
from methyl ketones, electron-deficient
acetylenes and ammonium acetate†
Cite this: Org. Biomol. Chem., 2021,
19, 2703
Dmitrii A. Shabalin, * Marina Yu. Dvorko, Elena Yu. Schmidt and
Boris A. Trofimov
*
A novel one-pot two-step approach for the synthesis of 2,4,6-triarylpyridines via t-BuOK/DMSO-pro-
moted C-vinylation of a variety of methyl ketones with electron-deficient acetylenes (alkynones) followed
by a cyclization of the in situ generated unsaturated 1,5-dicarbonyl species with ammonium acetate has
been developed. This approach possesses competitive advantages such as high regioselectivity, available
starting materials and the absence of transition-metal catalysts, oxidants and undesirable byproducts.
A wide synthetic utility of the developed approach was demonstrated by the synthesis of trisubstituted,
tetrasubstituted and fused pyridines.
Received 1st February 2021,
Accepted 1st March 2021
DOI: 10.1039/d1ob00193k
rsc.li/obc
three carbon substrates with 1-arylethylamines (Scheme 1B),13
ethyl nitroacetate/boronic acids (Scheme 1C),14 enaminones
Introduction
2,4,6-Triarylpyridines (TAPs, Kröhnke pyridines) and their (Scheme 1D),15 cyclic sulfamidate imines (Scheme 1E)16 etc.
bench-stable salts (Katritzky salts) are valuable building blocks
The recent trends of organic synthesis, raised by green
in synthetic1 and supramolecular2 chemistry as well as in the chemistry and pot-atom-step-economy (PASE)17 paradigms,
design of advanced devices. In particular, they are exploited as have encouraged synthetic community to modify existing and
components of OLEDs,3 hole-transporting materials for solar to find new methods for the assembly of well-known molecular
cells,4 and optical sensors.5 Recently, TAPs-based metal– architectures in order to mitigate negative environmental
organic frameworks have been synthesized and used for highly impacts. In this context, there is a perfect field for researches
selective detection of ions6 and small molecules7 and for sep- on the regiocontrolled synthesis of TAPs with a special focus
aration of gas mixtures.8 Moreover, TAPs demonstrate a great on minimizing the formation of undesirable byproducts and
potential for the treatment of cancer acting as topoisomerase excluding the use of transition-metal catalysts, oxidants and
inhibitors9 or G-quadruplex binding ligands.10
hardly-accessible starting materials.
Many synthetic approaches to the 2,4,6-triarylpyridine core
Acetylenes having highly reactive carbon–carbon triple
have been established to date.11 However, the development of bond represent an ideal structural unit for atom-economic and
convenient regiocontrolled syntheses of unsymmetrical TAPs energy-saving processes via diverse addition and cycloaddition
(R1 ≠ R2 ≠ R3, Scheme 1) still remains a challenge. The most reactions.18 As a part of our long-standing research interest in
frequently employed in applied sciences approach to unsym- the chemistry of acetylenes, we have recently reported the first
metrical 2,4,6-triarylpyridines is known to be the Kröhnke pyri- example of direct C-vinylation of weakly nucleophilic ketones
dine synthesis3a,11c,12 comprising the nucleophilic addition of with terminal alkyl- and arylacetylenes19 to afford
pyridinium ylide to an α,β-enone (Scheme 1A). In this case, the β,γ-unsaturated ketones, which further have been successfully
formation of aromatic pyridine ring occurs through the elimin- applied as a platform for diverse cascade assemblies of valu-
ation of a pyridinium salt. Other, much less common, able carbo- and heterocyclic compounds.18d Building on our
methods are based on the reactions of diverse unsaturated experience, in the present work we propose a novel synthetic
approach toward 2,4,6-triarylpyridines, which relies on the
in situ generation of unsaturated 1,5-dicarbonyl intermediates
A.E. Favorsky Irkutsk Institute of Chemistry SB RAS, 1 Favorsky St, Irkutsk, 664033,
through base-promoted C-vinylation of methyl ketones with
Russian Federation. E-mail: shabalin.chemistry@gmail.com,
electron-deficient acetylenes (alkynones) (Scheme 2A). The pro-
boris_trofimov@irioch.irk.ru
posed method has a number of obvious benefits in compari-
†Electronic supplementary information (ESI) available. See DOI: 10.1039/
son with previously reported synthetic protocols toward
d1ob00193k
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Scheme 1 Selected examples of regiocontrolled syntheses of TAPs.
Scheme 2 One-pot two-step regiocontrolled synthesis of TAPs from methyl ketones, electron-deficient acetylenes and ammonium acetate.
unsymmetrical TAPs (cf. Scheme 1), being only partly related to
Results and discussion
the Bohlmann–Rahtz pyridine synthesis (Scheme 2B)11c,20
from substrate point of view and to the Chichibabin reaction The conventional way to convert methyl ketones to C-anionic
(Scheme 2C)11c,21 from mechanistic point of view.
nucleophilic species comprises their treatment with strong
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bases such as lithium diisopropylamide, alkali metals hydrox- Finally, the desired unsaturated 1,5-diketone 3a was obtained
ides and alkoxides etc. At the same time, it is well known that in 83% isolated yield, when acetophenone (1a), 1,3-diphenyl-
alkynones as highly reactive compounds22 are susceptible to prop-2-yn-1-one (2a), and t-BuOK in a molar ratio of 1 : 2 : 2
hydrolytic cleavage and anionic polymerization under similar were reacted in DMSO (0.125 M per 1a) at room temperature
conditions.23 We have assumed that one possibility to solve for 0.5 h.
this dilemma is the use of non-nucleophilic superbasic
Next, 2,4,6-triphenylpyridine (4a) was easily synthesized in
systems capable of ensuring the high concentration of anionic 76% isolated yield via a one-pot two-step approach consisting
species even at room temperature.24 As a matter of fact, the of t-BuOK/DMSO-promoted addition of acetophenone (1a) to
model reaction between equimolar amounts of acetophenone 1,3-diphenylprop-2-yn-1-one (2a, Table 1, entry 17) followed by
(1a) and 1,3-diphenylprop-2-yn-1-one (2a) in the presence of the treatment of resulting reaction mixture with ammonium
superbasic system potassium tert-butoxide/dimethylsulfoxide acetate (5.0 equiv. per 1a) at 60 °C for 5 h. Further, the sub-
at room temperature for 0.5 h afforded the desired unsaturated strate scope of the novel synthetic approach to 2,4,6-triarylpyri-
1,5-diketone 3a exclusively as E-isomer in 68% yield (Table 1, dines was studied.
entry 1). Although the studied range of the reaction time and
As follows from Scheme 3 and Table S1 (see ESI†), aceto-
temperature had no remarkable effect on the reaction outcome phenones bearing trifluoromethyl, bromo and chloro substitu-
(entries 2–4) the addition of t-BuOK to the mixture of reactants ents at the para-position of the benzene ring smoothly reacted
in DMSO was found to be slightly exothermic that should be with 1,3-diphenylprop-2-yn-1-one (2a) under the same con-
taken into account for gram-scale syntheses. The decrease in ditions to afford the pyridines 4c–e in good yields (82–87%).
the amount of t-BuOK to 0.5 equiv. per 1a resulted in the for- The presence of electron-donating groups as exemplified by
mation of diketone 3a in a low yield (12%, entry 5) probably the reactivity of 4-methyl and 4-methoxyacetophenones
because of deactivation of the base through the side reactions required somewhat harsher reaction conditions on the second
with CH-acidic 3a and reactive acetylene 2a. Among the bases stage (a longer reaction time and
a greater excess of
tested, only t-BuOK and t-BuONa showed a good catalytic ammonium acetate) to provide a full conversion of the inter-
activity (entries 1 and 6–8). The choice of the solvent (in this mediate 1,5-dicarbonyl compounds to pyridines 4b and 4f (in
case, a ligand toward alkali metal cation) was pivotal; DMF, 69% and 61% yields, respectively). Interestingly, the best yields
NMP, MeCN, and toluene were tested and gave the signifi- of pyridines 4h and 4i (65% and 54%, respectively, Scheme 3)
cantly lower yields of diketone 3a (entries 9–12). Next, the ratio were achieved when the first stage, the reaction of 2-acetyl-
and concentration of the reactants were varied (entries 13–17). furan or 2-acetylthiophene with 1,3-diphenylprop-2-yn-1-one
Table 1 Optimization of the C-vinylation of acetophenone (1a) with 1,3-diphenylprop-2-yn-1-one (2a)a
Entry
Base
Solvent
Conditions
Conversion of 1a,b [%]
Yield of 3a,b [%]
1
2
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (0.5 equiv.)
t-BuONa (1.0 equiv.)
KOH·0.5H2O (1.0 equiv.)
DBU (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.0 equiv.)
t-BuOK (1.5 equiv.)
t-BuOK (1.5 equiv.)
t-BuOK (1.5 equiv.)
t-BuOK (2.0 equiv.)
DMSO (0.25 M)
DMSO (0.25 M)
DMSO (0.25 M)
DMSO/THF (0.25 M)
DMSO (0.25 M)
DMSO (0.25 M)
DMSO (0.25 M)
DMSO (0.25 M)
DMF (0.25 M)
rt, 0.5 h
rt, 0.25 h
40 °C, 0.5 h
15 °C, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
rt, 0.5 h
93
90
90
83
67
95
55
50
55
62
35
83
68
56
50
68
12
54
8
6
23
35
4
25
3
4c
5
6
7
8
9
10
11
12
13d
14d
15d
16d
17f
NMP (0.25 M)
MeCN (0.25 M)
toluene (0.25 M)
DMSO (0.25 M)
DMSO (0.25 M)
DMSO (0.5 M)
DMSO (0.125 M)
DMSO (0.125 M)
85
45
100
100
100
100
77
77 (73)e
80
88 (83)g
a Reaction conditions: 1a (0.25 mmol), 2a (0.25 mmol), the amount of base and solvent was calculated per 1a in accordance with the equivalent
ratios and molarities given in the Table 1. b Yields determined by 1H NMR using durene as an internal standard. c The mixture of DMSO/THF
(10 : 1 v/v ratio) was used. d Molar ratio of 1a : 2a = 1 : 1.5. e In parentheses isolated yield is given for reaction on 10.0 mmol scale. f Molar ratio of
1a : 2a = 1 : 2, unreacted 2a was registered by IR spectroscopy in a crude after reaction completion. g In parentheses isolated yield is given for reac-
tion on 0.5 mmol scale.
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Scheme 3 The methyl ketones scope of the one-pot two-step regiocontrolled approach to TAPs. Reaction conditions: ketone 1 (0.375 mmol), 1,3-
diphenylprop-2-yn-1-one 2a (0.75 mmol), t-BuOK (0.75 mmol), DMSO (3 mL). Pyridine 4j was synthesized on 2.5 mmol scale. Isolated yields are
given.
(2a), was conducted at elevated temperature (60 °C). To test the corresponding dipyridine 4g, ferrocenylpyridine 4k and tert-
scalability of the one-pot two-step protocol we performed the butylpyridine 4l, respectively (Scheme 3).
reaction of 2-acetylpyridine with 1,3-diphenylprop-2-yn-1-one
(2a) in 2.5 mmol scale and obtained 2,2′-bipyridine 4j in excel- using acetophenone (1a) as
Next, a set of alkynones was subjected to a similar reaction
model methyl ketone
a
lent 95% isolated yield. Moreover, several more exotic methyl (Scheme 4). The corresponding pyridines were synthesized in
ketones, namely 1,4-diacetylbenzene, acetylferrocene and 3,3- good yields (60–89%) from alkynones having aryl and hetaryl
dimethylbutan-2-one were successfully transformed into the substituents both at the carbon–carbon triple bond and the
Scheme 4 The alkynones scope of the one-pot two-step regiocontrolled approach to TAPs. Reaction conditions: ketone 1 (0.375 mmol), alkynone
2 (0.75 mmol), t-BuOK (0.75 mmol), DMSO (3 mL). Isolated yields are given.
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Scheme 5 Tentative reaction mechanism of the one-pot two-step regiocontrolled synthesis of unsymmetrical TAPs. Reaction conditions: ketone 1
(0.375 mmol), alkynone 2 (0.75 mmol), t-BuOK (0.75 mmol), DMSO (3 mL). Isolated yields are given.
carbonyl function (Scheme 4). However, the alkynones having regiocontrol), although arylpropynals (R3 = H) are known to
at least one alkyl substituent were less effective in the studied give aldol type products E under similar basic conditions.25
reaction. Thus, 3-cyclohexyl-1-phenylprop-2-yn-1-one was con-
Once the main goal of our study had been reached, we pro-
verted to 4-cyclohexyl-2,6-diphenylpyridine 4r in only 32% posed that the developed synthetic approach has a greater
yield, while the reactions of acetophenone (1a) with 3-phenyl- scope and may be extended to the design of more substituted
1-alkylprop-2-yn-1-ones (examples of alkyl groups were methyl, pyridines (Scheme 6). Thus, when propiophenone and butyro-
propyl and cyclohexyl) failed to yield pyridines and led to the phenone as acetophenone homologues were employed in the
complex reaction mixtures apparently due to side reactions reaction with 1,3-diphenylprop-2-yn-1-one (2a), the corres-
initiated by competing deprotonation of alkyl moieties on the ponding 3-methyl-(6a) and 3-ethyl-(6b) 2,4,6-triphenylpyridines
first stage.
were formed in 93% and 62% yields, respectively. The use of
To examine the regioselectivity, the synthesis of unsymme- cyclohexanone and α-tetralone delivered the fused pyridines,
trical TAPs has been explored as well (Scheme 5A). As outlined namely tetrahydroquinoline 6c and dihydrobenzo[h]quinoline
in Scheme 5A, three representatives of unsymmetrical TAPs 6d, in 60% and 50% yields, respectively. Obviously, the above
were obtained in good yields (77–81%) with total regiocontrol, mentioned transformations are just an illustration of a much
confirming that this approach could be used for the synthesis
of unsymmetrical TAPs from available methyl ketones and
electron-deficient acetylenes (alkynones).
Summarizing the results obtained, the following tentative
mechanism can be suggested (Scheme 5B). The reaction starts
from the formation of potassium enolate A from methyl
ketone 1 and t-BuOK, which further attacks the carbon–carbon
triple bond of alkynone 2 to afford potassium salt of unsatu-
rated 1,5-diketone B. The addition of ammonium acetate on
the second stage leads to neutralization of salt B with simul-
taneous nucleophilic addition of ammonia to the carbonyl
function. Intramolecular cyclization of the obtained amine C
followed by water molecule elimination from dihydropyridine
D completes the assembly of TAP. It is worth noting that no
Scheme 6 The extension of the one-pot two-step approach to the
synthesis of tetrasubstituted and fused pyridines. Reaction conditions:
product of competing addition of potassium enolate to the
ketone 5 (0.375 mmol), 1,3-diphenylprop-2-yn-1-one 2a (0.75 mmol),
carbon–oxygen double bond of alkynone 2 was detected (total t-BuOK (0.75 mmol), DMSO (3 mL). Isolated yields are given.
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broader range of potential manipulations to construct the over silica gel using hexane-diethyl ether (gradient from 1/0 to
desired pyridine derivatives.
0/1, v/v) as an eluent to afford the desired diketone 3a.
(E)-1,3,5-Triphenylpent-2-ene-1,5-dione (3a)
A cream solid (136 mg, 83% yield), mp 99–101 °C (lit.27
97–99 °C), Rf = 0.36 (hexane-diethyl ether, 3/1, v/v). 1H NMR
(400.1 MHz, CDCl3): δ = 8.08 (d, J = 7.4 Hz, 2H, Ph), 7.99 (d, J =
7.4 Hz, 2H, Ph), 7.61–7.53 (m, 4H, Ph), 7.51–7.44 (m, 4H, Ph,
1H, vCH), 7.43–7.40 (m, 3H, Ph), 4.87 (s, 2H, CH2). 13C{1H}
NMR (100.6 MHz, CDCl3): δ = 196.2, 191.0, 152.9, 142.2, 139.2,
137.2, 133.2, 132.8, 129.5, 128.9, 128.8, 128.7, 128.4, 128.4,
127.0, 123.8, 43.1. HRMS (ESI-TOF) calcd for [C23H18O2 + H]+
327.1385, found 327.1383.
Conclusions
In summary, we have disclosed a novel one-pot two-step regio-
controlled synthetic approach toward 2,4,6-triarylpyridines
based on the C-vinylation of methyl ketones with electron-
deficient acetylenes (alkynones) followed by cyclization of
in situ generated unsaturated 1,5-dicarbonyl intermediates
under treatment with ammonium acetate. The amenability of
the proposed reaction sequence to diversely decorated methyl
ketones and alkynones was evaluated, making it possible to
synthesize a number of 2,4,6-triarylpyridines in good-to-excel-
lent yields. Furthermore, tetrasubstituted and fused pyridines
were shown to be accessible through our method using methyl
ketones homologues.
General procedure for the synthesis of pyridines 4 and 6
A 10 mL round-bottom flask with stir bar was sequentially
charged with ketone (0.375 mmol), alkynone (0.75 mmol) and
DMSO (3 mL). Then t-BuOK (84 mg, 0.75 mmol) was added,
the reaction flask was capped with a glass stopper, and the
reaction mixture was stirred at room temperature (20–24 °C) or
at 60 °C for 0.5 h. Then NH4OAc (144 mg, 1.875 mmol, 5
equiv.) was added to the flask, a glass stopper was replaced by
a reflux condenser, and the reaction mixture was stirred at
60 °C or 80 °C for 5–8 h. In some cases the addition of
NH4OAc (144 mg, 1.875 mmol, 5 equiv.) was repeated after the
first 4 h (see Table S1† for detailed reaction conditions). The
reaction mixture was then quenched with water (20 mL) and
extracted with diethyl ether (3 × 10 mL). The combined
organic extracts were washed with water (2 × 5 mL) and dried
(MgSO4). After removal of the solvent, the residue was purified
by column chromatography over silica gel using hexane-diethyl
ether (gradient from 1/0 to 0/1, v/v) as an eluent to afford the
desired pyridine 4 and 6.
Experimental
All chemicals and solvents were purchased from commercial
sources. Starting alkynones were synthesized according to the
published method.26 Thin layer chromatography was carried
out on Merck silica gel 60 F254 pre-coated aluminium foil
sheets and were visualized using UV light (254 nm). Column
chromatography was carried out using slurry packed Sigma
Aldrich silica gel (SiO2), 70–230 mesh, pore size 60 Å. NMR
spectra were recorded from solutions in CDCl3 on Bruker
DPX-400 and AV-400 spectrometers (400.1 MHz for 1H and
100.6 MHz for 13C). Chemical shifts (δ) are quoted in parts per
million (ppm). The residual solvent peak, δH 7.26 and δC
77.10, was used as a reference. Coupling constants (J) are
reported in Hertz (Hz). The multiplicity abbreviations used
are: s singlet, d doublet, dd doublet of doublet, t triplet, m
multiplet, br broad signal. High-resolution mass spectra were
recorded from acetonitrile solution with 0.1% HFBA on HPLC
Agilent 1200/Agilent 6210 TOF instrument equipped with elec-
trospray ionization (ESI) source. Melting points (uncorrected)
2,4,6-Triphenylpyridine (4a)
Following the general procedure, 4a was prepared from aceto-
phenone (45 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
one (155 mg, 0.75 mmol), isolated as a light yellow solid
(88 mg, 76% yield), mp 135–137 °C (lit.13 140–141 °C), Rf =
0.64 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz,
CDCl3): δ = 8.22 (d, J = 7.4 Hz, 4H), 7.90 (s, 2H), 7.76 (d, J = 7.4
Hz, 2H), 7.54–7.44 (m, 9H). 13C{1H} NMR (100.6 MHz, CDCl3):
δ = 157.6, 150.6, 139.7, 139.2, 129.2, 129.1, 129.1, 128.8, 127.3,
127.3, 117.2. HRMS (ESI-TOF) calcd for [C23H17N + H]+
308.1439, found 308.1437.
were measured on
Electrothermal IA 9200.
a digital melting point apparatus
Procedure for the synthesis of diketone 3a
A 10 mL round-bottom flask with stir bar was sequentially
charged with acetophenone (1a, 60 mg, 0.5 mmol), 1,3-diphe-
2,4-Diphenyl-6-(p-tolyl)pyridine (4b)
nylprop-2-yn-1-one (2a, 206 mg, 1.0 mmol) and DMSO (4 mL). Following the general procedure, 4b was prepared from 4′-
Then t-BuOK (112 mg, 1.0 mmol) was added, the reaction flask methylacetophenone (50 mg, 0.375 mmol) and 1,3-diphenyl-
was capped with a glass stopper, and the reaction mixture was prop-2-yn-1-one (155 mg, 0.75 mmol) and isolated as a light
stirred at room temperature (20–24 °C) for 0.5 h. The reaction yellow solid (83 mg, 69% yield) OR 4b was prepared from aceto-
mixture was then quenched with water (20 mL), neutralized phenone (45 mg, 0.375 mmol) and 3-phenyl-1-(p-tolyl)prop-2-
with 10% HCl(aq), and extracted with diethyl ether (3 × yn-1-one (165 mg, 0.75 mmol) and isolated as a light yellow
10 mL). The combined organic extracts were washed with solid (75 mg, 62% yield), mp 120–121 °C (lit.13 119–120 °C),
1
water (2 × 5 mL) and dried (MgSO4). After removal of the Rf = 0.73 (hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz,
solvent, the residue was purified by column chromatography CDCl3): δ = 8.21 (d, J = 7.3 Hz, 2H), 8.12 (d, J = 8.1 Hz, 2H),
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7.87 (s, 2H), 7.75 (d, J = 7.0 Hz, 2H), 7.55–7.43 (m, 6H), 7.33 (d, yellow solid (77 mg, 61% yield) OR 4f was prepared from aceto-
J = 8.1 Hz, 2H), 2.44 (s, 3H). 13C{1H} NMR (100.6 MHz, CDCl3): phenone (45 mg, 0.375 mmol) and 1-(4-methoxyphenyl)-3-phe-
δ = 157.6, 157.5, 150.2, 139.8, 139.3, 139.1, 136.9, 129.5, 129.2, nylprop-2-yn-1-one (177 mg, 0.75 mmol) and isolated as a light
129.1, 129.0, 128.8, 127.3, 127.3, 127.1, 116.9, 116.9, 21.4. yellow solid (92 mg, 73% yield), mp 99–101 °C (lit.13
1
HRMS (ESI-TOF) calcd for [C24H19N + H]+ 322.1596, found 106–108 °C), Rf = 0.57 (hexane-diethyl ether, 3/1, v/v). H NMR
322.1593.
(400.1 MHz, CDCl3): δ = 8.22 (d, J = 7.8 Hz, 2H), 8.20 (d, J = 8.8
Hz, 2H), 7.85 (s, 1H), 7.85 (s, 1H), 7.76 (d, J = 7.2 Hz, 2H),
7.56–7.44 (m, 6H), 7.06 (d, J = 8.8 Hz, 2H), 3.90 (s, 3H). 13C{1H}
2,4-Diphenyl-6-(4-(trifluoromethyl)phenyl)pyridine (4c)
Following the general procedure, 4c was prepared from 4′-(tri- NMR (100.6 MHz, CDCl3): δ = 160.7, 157.5, 157.2, 150.2, 139.8,
fluoromethyl)acetophenone (71 mg, 0.375 mmol) and 1,3- 139.3, 132.4, 129.2, 129.1, 129.0, 128.8, 128.5, 127.3, 127.2,
diphenylprop-2-yn-1-one (155 mg, 0.75 mmol), isolated as a 116.6, 116.4, 114.2, 55.5. HRMS (ESI-TOF) calcd for [C24H19NO
light yellow solid (116 mg, 82% yield), mp 136–137 °C (lit.28 + H]+ 338.1544, found 338.1544.
1
135–137 °C), Rf = 0.65 (hexane-diethyl ether, 3/1, v/v). H NMR
(400.1 MHz, CDCl3): δ = 8.32 (d, J = 8.3 Hz, 2H), 8.21 (d, J = 7.0
1,4-Bis(4,6-diphenylpyridin-2-yl)benzene (4g)
Hz, 2H), 7.95 (s, 1H), 7.92 (s, 1H), 7.79–7.75 (m, 4H), 7.58–7.46 Following the general procedure, 4g was prepared from 1,4-di-
(m, 6H). 13C{1H} NMR (100.6 MHz, CDCl3): δ = 157.8, 155.9, acetylbenzene (61 mg, 0.375 mmol), 1,3-diphenylprop-2-yn-1-
150.5, 143.0, 139.3, 138.8, 130.9 (q, J = 32.3), 129.4, 129.3, one (310 mg, 1.5 mmol), potassium tert-butoxide (168 mg,
129.3, 128.9, 127.5, 127.3, 127.2, 125.7 (q, J = 3.8 Hz), 124.4 (q, 1.5 mmol) and ammonium acetate (288 mg, 3.75 mmol) in
J = 272.0 Hz), 117.9, 117.4. HRMS (ESI-TOF) calcd for DMSO (3 mL) OR 4g was prepared from acetophenone (90 mg,
[C24H16F3N + H]+ 376.1313, found 376.1313.
0.75 mmol), 1,1′-(1,4-phenylene)bis(3-phenylprop-2-yn-1-one)
(125 mg, 0.375 mmol), potassium tert-butoxide (112 mg,
0.75 mmol) and ammonium acetate (288 mg, 3.75 mmol) in
2-(4-Chlorophenyl)-4,6-diphenylpyridine (4d)
Following the general procedure, 4d was prepared from 4′- DMSO (3 mL). The reaction mixture after cooling to room
chloroacetophenone (58 mg, 0.375 mmol) and 1,3-diphenyl- temperature was diluted with water (15 mL), and extracted
prop-2-yn-1-one (155 mg, 0.75 mmol) and isolated as a light with DCM (3 × 10 mL). The combined organic extracts were
yellow solid (109 mg, 85% yield), OR 4d was prepared from washed with water (2 × 5 mL) and dried (CaCl2). After removal
acetophenone (45 mg, 0.375 mmol) and 1-(4-chlorophenyl)-3- of the solvent, the residue was treated with diethyl ether and
phenylprop-2-yn-1-one (181 mg, 0.75 mmol) and isolated as a 4g was isolated as a brown solid (143 mg, 71% yield OR
light yellow solid (114 mg, 89% yield), mp 133–134 °C (lit.13 122 mg, 61% yield), mp 292–294 °C (lit.29 302–304 °C). 1H
1
120–122 °C), Rf = 0.70 (hexane-diethyl ether, 3/1, v/v). H NMR NMR (400.1 MHz, CDCl3): δ = 8.38 (s, 4H), 8.25 (d, J = 7.6 Hz,
(400.1 MHz, CDCl3): δ = 8.20 (d, J = 7.3 Hz, 2H), 8.16 (d, J = 8.5 4H), 7.99 (s, 2H), 7.93 (s, 2H), 7.79 (d, J = 7.3 Hz, 4H),
Hz, 2H), 7.90 (s, 1H), 7.86 (s, 1H), 7.75 (d, J = 7.1 Hz, 2H), 7.58–7.46 (m, 12H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
7.56–7.45 (m, 8H). 13C{1H} NMR (100.6 MHz, CDCl3): δ = 157.8, 157.2, 150.5, 140.3, 139.8, 139.3, 129.3, 129.3, 129.2,
157.6, 156.2, 150.4, 139.4, 138.9, 138.0, 135.2, 129.2, 129.2, 128.9, 127.6, 127.4, 127.3, 117.5, 117.4. HRMS (ESI-TOF) calcd
129.1, 128.9, 128.8, 128.5, 127.2, 127.2, 117.4, 116.8. HRMS for [C40H28N2 + H]+ 537.2331, found 537.2334.
(ESI-TOF) calcd for [C23H16ClN
342.1048.
+
H]+ 342.1050, found
2-(Furan-2-yl)-4,6-diphenylpyridine (4h)
Following the general procedure, 4h was prepared from
2-acetylfuran (41 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-
2-(4-Bromophenyl)-4,6-diphenylpyridine (4e)
Following the general procedure, 4e was prepared from 4′-bro- 1-one (155 mg, 0.75 mmol) and isolated as a light yellow solid
moacetophenone (75 mg, 0.375 mmol) and 1,3-diphenylprop- (72 mg, 65% yield) OR 4h was prepared from acetophenone
2-yn-1-one (155 mg, 0.75 mmol), isolated as a light yellow solid (45 mg, 0.375 mmol) and 1-(furan-2-yl)-3-phenylprop-2-yn-1-
(126 mg, 87% yield), mp 153–155 °C (lit.28 151–153 °C), Rf = one (147 mg, 0.75 mmol) and isolated as a light yellow solid
0.68 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz, (70 mg, 63% yield), mp 87–88 °C (lit.28 90–92 °C), Rf = 0.68
CDCl3): δ = 8.19 (d, J = 7.1 Hz, 2H), 8.10 (d, J = 8.6 Hz, 2H), (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz, CDCl3):
7.91 (s, 1H), 7.86 (s, 1H), 7.74 (d, J = 6.9 Hz, 2H), 7.64 (d, J = δ = 8.17 (d, J = 7.2 Hz, 2H), 7.90 (s, 1H), 7.83 (s, 1H), 7.77 (d, J =
8.6 Hz, 2H), 7.56–7.44 (m, 6H). 13C{1H} NMR (100.6 MHz, 7.0 Hz, 2H), 7.59–7.44 (m, 7H), 7.27 (d, J = 3.3 Hz, 1H), 6.59
CDCl3): δ = 157.7, 156.3, 150.4, 139.5, 138.9, 138.5, 131.9, (dd, J = 1.5 Hz, J = 3.3 Hz, 1H). 13C{1H} NMR (100.6 MHz,
129.3, 129.2, 129.2, 128.8, 128.8, 127.3, 127.2, 123.6, 117.5, CDCl3): δ = 157.8, 154.3, 150.1, 149.9, 143.3, 139.5, 138.9,
116.8. HRMS (ESI-TOF) calcd for [C23H16BrN + H]+ 386.0544, 129.2, 129.2, 128.8, 127.3, 127.2, 117.0, 115.2, 112.2, 109.2.
found 386.0546.
HRMS (ESI-TOF) calcd for [C21H15NO + H]+ 298.1232, found
298.1230.
2-(4-Methoxyphenyl)-4,6-diphenylpyridine (4f)
2,4-Diphenyl-6-(thiophen-2-yl)pyridine (4i)
Following the general procedure, 4f was prepared from 4′-
methoxyacetophenone (56 mg, 0.375 mmol) and 1,3-diphenyl- Following the general procedure, 4i was prepared from 2-acetyl-
prop-2-yn-1-one (155 mg, 0.75 mmol) and isolated as a light thiophene (47 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
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one (155 mg, 0.75 mmol) and isolated as a light yellow solid 4,6-Diphenyl-2,3′-bipyridine (4m)
(63 mg, 54% yield) OR 4i was prepared from acetophenone
Following the general procedure, 4m was prepared from aceto-
(45 mg, 0.375 mmol) and 3-phenyl-1-(thiophen-2-yl)prop-2-yn-
1-one (159 mg, 0.75 mmol) and isolated as a light yellow solid
(70 mg, 60% yield), mp 105–106 °C (lit.28 112–114 °C), Rf =
0.66 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz,
CDCl3): δ = 8.20 (d, J = 7.1 Hz, 2H), 7.82 (s, 1H), 7.80 (s, 1H),
7.75–7.74 (m, 3H), 7.56–7.44 (m, 7H), 7.17–7.15 (m, 1H). 13C
{1H} NMR (100.6 MHz, CDCl3): δ = 157.5, 152.9, 150.3, 145.6,
139.2, 139.0, 129.3, 129.3, 129.2, 128.9, 128.1, 127.8, 127.3,
127.2, 124.8, 116.9, 115.5. HRMS (ESI-TOF) calcd for
[C21H15NS + H]+ 314.1003, found 314.1002.
phenone (45 mg, 0.375 mmol) and 3-phenyl-1-(pyridin-3-yl)
prop-2-yn-1-one (155 mg, 0.75 mmol), isolated as a white solid
(79 mg, 68% yield), mp 153–155 °C (lit.31 161 °C), Rf = 0.60
1
(diethyl ether). H NMR (400.1 MHz, CDCl3): δ = 9.40 (s, 1H),
8.69 (d, J = 3.7 Hz, 1H), 8.51 (d, J = 7.9 Hz, 1H), 8.20 (d, J = 7.2
Hz, 2H), 7.93 (s, 1H), 7.88 (s, 1H), 7.74 (d, J = 6.9 Hz, 2H),
7.56–7.42 (m, 7H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
158.0, 155.0, 150.6, 150.1, 148.6, 139.2, 138.7, 135.1, 134.6,
129.4, 129.3, 128.9, 127.2, 127.2, 123.6, 117.8, 117.1. HRMS
(ESI-TOF) calcd for [C22H16N2 + H]+ 309.1392, found 309.1390.
4,6-Diphenyl-2,2′-bipyridine (4j)
2,6-Diphenyl-4-(p-tolyl)pyridine (4n)
Following the general procedure, 4j was prepared from 2-acetyl-
pyridine (303 mg, 2.5 mmol), 1,3-diphenylprop-2-yn-1-one
(1030 mg, 5.0 mmol), potassium tert-butoxide (560 mg,
2.5 mmol) and ammonium acetate (963 mg, 12.5 mmol) in
DMSO (10 mL, 0.25 M) and isolated as a white solid (732 mg,
95% yield), mp 156–158 °C (lit.30 157–158 °C), Rf = 0.24
Following the general procedure, 4n was prepared from aceto-
phenone (45 mg, 0.375 mmol) and 1-phenyl-3-(p-tolyl)prop-2-
yn-1-one (165 mg, 0.75 mmol), isolated as a light yellow solid
(95 mg, 79% yield), mp 117–118 °C (lit.13 118–120 °C), Rf =
0.71 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz,
CDCl3): δ = 8.27 (d, J = 7.5 Hz, 4H), 7.92 (s, 2H), 7.69 (d, J = 7.7
Hz, 2H), 7.59–7.56 (m, 4H), 7.52–7.48 (m, 2H), 7.37 (d, J = 7.7
Hz, 2H), 2.48 (s, 3H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
157.5, 150.1, 139.8, 139.1, 136.2, 129.9, 129.1, 128.8, 127.2,
127.1, 117.0, 21.3. HRMS (ESI-TOF) calcd for [C24H19N + H]+
322.1596, found 322.1593.
1
(hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ
= 8.74–8.70 (m, 2H), 8.68 (s, 1H), 8.23 (d, J = 7.3 Hz, 2H), 8.00
(s, 1H), 7.89–7.83 (m, 3H), 7.57–7.51 (m, 4H), 7.49–7.46 (m,
2H), 7.35–7.33 (m, 1H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
157.3, 156.5, 156.4, 150.4, 149.2, 139.6, 138.9, 137.0, 129.2,
129.1, 129.1, 128.9, 127.4, 127.2, 123.9, 121.6, 118.6, 117.7.
HRMS (ESI-TOF) calcd for [C22H16N2 + H]+ 309.1392, found
309.1393.
4-(3-Fluorophenyl)-2,6-diphenylpyridine (4o)
Following the general procedure, 4o was prepared from aceto-
phenone (45 mg, 0.375 mmol) and 3-(3-fluorophenyl)-1-phe-
nylprop-2-yn-1-one (168 mg, 0.75 mmol), isolated as a light
yellow solid (98 mg, 80% yield), mp 128–130 °C (lit.13
2-Ferrocenyl-4,6-diphenylpyridine (4k)
Following the general procedure, 4k was prepared from acetyl-
ferrocene (86 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
one (155 mg, 0.75 mmol), isolated as an orange oil (80 mg,
1
138–139 °C), Rf = 0.65 (hexane-diethyl ether, 3/1, v/v). H NMR
(400.1 MHz, CDCl3): δ = 8.22 (d, J = 7.4 Hz, 4H), 7.87 (s, 2H),
7.56–7.45 (m, 9H), 7.20–7.17 (m, 1H). 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 163.4 (d, J = 246.9 Hz), 157.8, 149.0 (d,
J = 2.0 Hz), 141.5 (d, J = 7.8 Hz), 139.5, 130.8 (d, J = 8.3 Hz),
129.3, 128.9, 127.3, 123.0 (d, J = 2.8 Hz), 117.0, 116.0 (d, J =
21.1 Hz), 114.3 (d, J = 22.4 Hz). HRMS (ESI-TOF) calcd for
[C23H16FN + H]+ 326.1345, found 326.1343.
1
51% yield), Rf = 0.66 (hexane-diethyl ether, 3/1, v/v). H NMR
(400.1 MHz, CDCl3): δ = 8.22 (d, J = 7.1 Hz, 2H), 7.77–7.75 (m,
3H), 7.58–7.45 (m, 7H), 5.12–5.11 (m, 2H), 4.46–4.45 (m, 2H),
4.12 (s, 5H). 13C{1H} NMR (100.6 MHz, CDCl3): δ = 160.0,
157.1, 149.3, 139.9, 139.4, 129.2, 129.0, 129.0, 128.8, 127.3,
127.2, 116.7, 115.7, 84.5, 70.0, 69.8, 67.8. HRMS (ESI-TOF)
calcd for [C27H21FeN + H]+ 416.1102, found 416.1101.
4-(3-Methoxyphenyl)-2,6-diphenylpyridine (4p)
2-(tert-Butyl)-4,6-diphenylpyridine (4l)
Following the general procedure, 4p was prepared from aceto-
Following the general procedure, 4l was prepared from 3,3-di- phenone (45 mg, 0.375 mmol) and 3-(3-methoxyphenyl)-1-phe-
methylbutan-2-one (38 mg, 0.375 mmol) and 1,3-diphenyl- nylprop-2-yn-1-one (177 mg, 0.75 mmol), isolated as a light
prop-2-yn-1-one (155 mg, 0.75 mmol), isolated as a light pink beige solid (85 mg, 67% yield), mp 122–124 °C (lit.32
1
solid (64 mg, 59% yield), mp 88–90 °C (lit.28 87–89 °C), Rf = 121–122 °C), Rf = 0.57 (hexane-diethyl ether, 3/1, v/v). H NMR
0.83 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz, (400.1 MHz, CDCl3): δ = 8.21 (d, J = 7.4 Hz, 4H), 7.89 (s, 2H),
CDCl3): δ = 8.23 (d, J = 7.2 Hz, 2H), 7.82 (s, 1H), 7.74 (d, J = 7.1 7.54–7.51 (m, 4H), 7.47–7.44 (m, 3H), 7.34 (d, J = 7.6 Hz, 1H),
Hz, 2H), 7.57–7.44 (m, 7H), 1.56 (s, 9H). 13C{1H} NMR 7.27–7.26 (m, 1H), 7.02 (d, J = 8.1 Hz, 1H), 3.91 (s, 3H). 13C{1H}
(100.6 MHz, CDCl3): δ = 169.7, 156.2, 149.6, 140.1, 139.9, NMR (100.6 MHz, CDCl3): δ = 160.3, 157.6, 150.1, 140.6, 139.7,
129.1, 128.9, 128.7, 128.7, 127.4, 127.1, 115.9, 115.6, 38.0, 30.5. 130.3, 129.1, 128.8, 127.2, 119.7, 117.2, 114.3, 113.1, 55.5.
HRMS (ESI-TOF) calcd for [C21H21N + H]+ 288.1752, found HRMS (ESI-TOF) calcd for [C24H19NO + H]+ 338.1545, found
288.1752.
338.1545.
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2,6-Diphenyl-4-(thiophen-3-yl)pyridine (4q)
6-(Furan-2-yl)-4-phenyl-2,2′-bipyridine (4v)
Following the general procedure, 4q was prepared from aceto- Following the general procedure, 4v was prepared from 2-acetyl-
phenone (45 mg, 0.375 mmol) and 1-phenyl-3-(thiophen-3-yl) pyridine (45 mg, 0.375 mmol) and 1-(furan-2-yl)-3-phenyl-
prop-2-yn-1-one (159 mg, 0.75 mmol), isolated as a light yellow prop-2-yn-1-one (147 mg, 0.75 mmol), isolated as a light yellow
solid (87 mg, 74% yield), mp 143–145 °C, Rf = 0.66 (hexane- solid (89 mg, 80% yield), mp 145–147 °C, Rf = 0.16 (hexane-
1
1
diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ = 8.23 diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ = 8.72
(d, J = 7.2 Hz, 4H), 7.89 (s, 2H), 7.77 (s, 1H), 7.58–7.47 (m, 8H). (d, J = 4.0 Hz, 1H), 8.61–8.59 (m, 2H), 7.97–7.96 (m, 1H),
13C{1H} NMR (100.6 MHz, CDCl3): δ = 157.7, 144.5, 140.4, 7.87–7.82 (m, 3H), 7.58 (s, 1H), 7.53–7.44 (m, 3H), 7.32 (dd, J =
139.7, 129.2, 128.8, 127.2, 127.1, 126.1, 123.1, 116.3. HRMS 5.0 Hz, J = 6.5 Hz, 1H), 7.26 (d, J = 3.3 Hz, 1H), 6.59 (dd, J = 1.7
(ESI-TOF) calcd for [C21H15NS + H]+ 314.1003, found 314.1001.
Hz, J = 3.3 Hz, 1H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
156.4, 156.1, 154.2, 150.1, 149.4, 149.1, 143.3, 138.5, 136.9,
129.1, 129.0, 127.2, 123.9, 121.5, 117.3, 116.4, 112.2, 109.0.
HRMS (ESI-TOF) calcd for [C20H14N2O + H]+ 299.1184, found
299.1186.
4-Cyclohexyl-2,6-diphenylpyridine (4r)
Following the general procedure, 4r was prepared from aceto-
phenone (45 mg, 0.375 mmol) and 3-cyclohexyl-1-phenylprop-
2-yn-1-one (159 mg, 0.75 mmol), isolated as a white solid
(38 mg, 32% yield), mp 102–104 °C (lit.33 97–99 °C), Rf = 0.77
3-Methyl-2,4,6-triphenylpyridine (6a)
1
Following the general procedure, 6a was prepared from propio-
phenone (50 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
one (155 mg, 0.75 mmol), isolated as a light yellow solid
(112 mg, 93% yield), mp 135–137 °C (lit.28 141–143 °C), Rf =
0.53 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz,
CDCl3): δ = 8.13 (d, J = 7.6 Hz, 2H), 7.73–7.71 (m, 2H), 7.66 (s,
1H), 7.54–7.40 (m, 11H), 2.29 (s, 3H). 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 159.6, 154.2, 151.7, 141.6, 140.4,
139.5, 129.6, 128.9, 128.7, 128.7, 128.6, 128.2, 128.0, 128.0,
127.1, 127.0, 120.1, 18.1. HRMS (ESI-TOF) calcd for [C24H19N +
H]+ 322.1596, found 322.1594.
(hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ
= 8.18 (d, J = 7.2 Hz, 4H), 7.57 (s, 2H), 7.54–7.51 (m, 4H),
7.46–7.43 (m, 2H), 2.70–2.63 (m, 1H), 2.02–1.99 (m, 2H),
1.95–1.92 (m, 2H), 1.85–1.82 (m, 1H), 1.62–1.42 (m, 4H),
1.39–1.29 (m, 1H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
158.1, 157.1, 140.0, 128.9, 128.7, 127.2, 117.8, 44.5, 33.8, 26.8,
26.1. HRMS (ESI-TOF) calcd for [C23H23N + H]+ 314.1909,
found 314.1910.
2-(4-Chlorophenyl)-4-(3-methoxyphenyl)-6-phenylpyridine (4t)
Following the general procedure, 4t was prepared from 4′-
chloroacetophenone (58 mg, 0.375 mmol) and 3-(3-methoxy- 3-Ethyl-2,4,6-triphenylpyridine (6b)
phenyl)-1-phenylprop-2-yn-1-one (177 mg, 0.75 mmol), isolated
Following the general procedure, 6b was prepared from butyro-
as a white solid (108 mg, 77% yield), mp 107–108 °C, Rf = 0.56
phenone (56 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
one (155 mg, 0.75 mmol), isolated as a light yellow solid
(78 mg, 62% yield), mp 91–93 °C (lit.34 99–100 °C), Rf = 0.61
1
(hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ
= 8.19–8.15 (m, 4H), 7.89 (s, 1H), 7.84 (s, 1H), 7.55–7.44 (m,
6H), 7.32 (d, J = 7.5 Hz, 1H), 7.27–7.26 (m, 1H, overlaped), 7.01
(d, J = 8.2 Hz, 1H), 3.91 (s, 3H). 13C{1H} NMR (100.6 MHz,
CDCl3): δ = 160.3, 157.6, 156.2, 150.2, 140.4, 139.4, 138.0,
135.2, 130.3, 129.2, 128.9, 128.8, 128.4, 127.2, 119.6, 117.4,
116.9, 114.3, 113.2, 55.5. HRMS (ESI-TOF) calcd for
[C24H18ClNO + H]+ 372.1155, found 372.1154.
1
(hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ
= 8.12 (d, J = 7.5 Hz, 2H), 7.68 (d, J = 7.5 Hz, 2H), 7.63 (s, 1H),
7.55–7.40 (m, 11H), 2.77 (q, J = 7.4 Hz, 2H), 0.84 (t, J = 7.4 Hz,
3H). 13C{1H} NMR (100.6 MHz, CDCl3): δ = 159.7, 153.8, 151.4,
141.8, 140.5, 139.3, 133.5, 129.1, 128.7, 128.6, 128.6, 128.6,
128.4, 128.1, 127.7, 127.0, 120.7, 22.2, 14.9. HRMS (ESI-TOF)
calcd for [C25H21N + H]+ 336.1752, found 336.1754.
2-(4-Bromophenyl)-6-(4-chlorophenyl)-4-phenylpyridine (4u)
2,4-Diphenyl-5,6,7,8-tetrahydroquinoline (6c)
Following the general procedure, 4u was prepared from 4′-bro-
moacetophenone (75 mg, 0.375 mmol) and 1-(4-chlorophenyl)- Following the general procedure, 6c was prepared from cyclo-
3-phenylprop-2-yn-1-one (181 mg, 0.75 mmol), isolated as a hexanone (37 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-
light yellow solid (128 mg, 81% yield), mp 188–190 °C, Rf = one (155 mg, 0.75 mmol), isolated as a light yellow solid
0.77 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz, (64 mg, 60% yield), mp 100–102 °C (lit.28 102–104 °C), Rf =
CDCl3): δ = 8.13 (d, J = 8.6 Hz, 2H), 8.07 (d, J = 8.6 Hz, 2H), 0.53 (hexane-diethyl ether, 3/1, v/v). 1H NMR (400.1 MHz,
7.86 (s, 2H), 7.73 (d, J = 6.9 Hz, 2H), 7.64 (d, J = 8.6 Hz, 2H), CDCl3): δ = 7.99 (d, J = 7.1 Hz, 2H), 7.48–7.35 (m, 9H), 3.11 (t, J
7.56–7.48 (m, 5H). 13C{1H} NMR (100.6 MHz, CDCl3): δ = = 6.5 Hz, 2H), 2.67 (t, J = 6.2 Hz, 2H), 1.99–1.93 (m, 2H),
156.6, 156.5, 150.8, 138.8, 138.4, 137.9, 135.5, 132.0, 129.4, 1.80–1.74 (m, 2H). 13C{1H} NMR (100.6 MHz, CDCl3): δ =
129.3, 129.1, 128.8, 128.5, 127.3, 123.8, 117.3, 117.2. HRMS 157.8, 154.4, 150.3, 139.9, 139.9, 128.7, 128.7, 128.7, 128.5,
(ESI-TOF) calcd for [C23H15BrClN + H]+ 422.0134, found 128.4, 127.8, 127.0, 119.2, 33.5, 27.4, 23.2, 23.2. HRMS
422.0144.
(ESI-TOF) calcd for [C21H19N + H]+ 286.1596, found 286.1593.
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2,4-Diphenyl-5,6-dihydrobenzo[h]quinoline (6d)
Reversible Molecular Switch of Acridine Red by
Triarylpyridine-Modified Cyclodextrin, Org. Lett., 2013, 15,
124–127; (d) H. Wang, C.-H. Liu, K. Wang, M. Wang, H. Yu,
S. Kandapal, R. Brzozowski, B. Xu, M. Wang, S. Lu,
X.-Q. Hao, P. Eswara, M.-P. Nieh, J. Cai and X. Li,
Assembling Pentatopic Terpyridine Ligands with Three
Following the general procedure, 6d was prepared from 1-tetra-
lone (55 mg, 0.375 mmol) and 1,3-diphenylprop-2-yn-1-one
(155 mg, 0.75 mmol), isolated as a light yellow solid (63 mg,
50% yield), mp 124–126 °C (lit.28 126–128 °C), Rf = 0.74
1
(hexane-diethyl ether, 3/1, v/v). H NMR (400.1 MHz, CDCl3): δ
Types of Coordination Moieties into
a
Giant
= 8.61 (d, J = 7.7 Hz, 1H), 8.21 (d, J = 8.3 Hz, 2H), 7.62 (s, 1H),
7.53–7.42 (m, 9H), 7.36 (t, J = 7.4 Hz, 1H), 7.25 (d, J = 8.5 Hz,
1H), 2.98–2.94 (m, 2H), 2.90–2.86 (m, 2H). 13C{1H} NMR
(100.6 MHz, CDCl3): δ = 154.6, 152.7, 149.4, 139.7, 139.5,
138.3, 135.4, 129.2, 128.9, 128.8, 128.8, 128.6, 128.1, 128.0,
127.6, 127.2, 126.9, 125.9, 120.0, 28.3, 25.4. HRMS (ESI-TOF)
calcd for [C25H19N + H]+ 334.1596, found 334.1593.
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Conflicts of interest
There are no conflicts to declare.
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Acknowledgements
The spectral data were obtained with the equipment of the
Baikal Analytical Center for collective use SB RAS. HRMS
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