Synthesis of Fluorescent 1,3-Diarylpropynones by Carbonylative Alkynylation Reaction Using (Phosphine) (1,2,3-triazol-5-ylidene)palladium Complexes as Catalysts

Article abstract of DOI:10.1002/ejoc.201600744

The synthesis of a variety of 1,3-diarylpropynones that contain not only substituted phenyl groups but also fluorophoric 1-pyrenyl, 3-carbazolyl, and 1-naphthyl groups was achieved in good to excellent yields by using a carbonylative alkynylation reaction in the presence of cis-(Tz)Pd(Cl)₂(PPh₃) (Tz = 1,2,3-triazol-5-ylidene) as a precatalyst under 1.0 atm of CO. Products resulting from competing Sonogashira coupling reactions, namely 1,2-diarylacetylenes, were not observed. The synthesized ynones exhibit fluorescence not only in solution but also in the solid state. The catalytically active palladium species was recovered and reused for up to three cycles by adsorbing the cis-(Tz)Pd(Cl)₂(PPh₃) precatalyst onto silica gel and carrying out the reaction under heterogeneous conditions.

Full text of DOI:10.1002/ejoc.201600744

DOI: 10.1002/ejoc.201600744
Full Paper
Carbonylative Alkynylation
Synthesis of Fluorescent 1,3-Diarylpropynones by Carbonylative
Alkynylation Reaction Using (Phosphine) (1,2,3-triazol-5-
ylidene)palladium Complexes as Catalysts
Ayan Dasgupta,[a] Venkatachalam Ramkumar,[a] and Sethuraman Sankararaman*[a]
Abstract: The synthesis of a variety of 1,3-diarylpropynones reactions, namely 1,2-diarylacetylenes, were not observed. The
that contain not only substituted phenyl groups but also fluoro- synthesized ynones exhibit fluorescence not only in solution
phoric 1-pyrenyl, 3-carbazolyl, and 1-naphthyl groups was but also in the solid state. The catalytically active palladium
achieved in good to excellent yields by using a carbonylative species was recovered and reused for up to three cycles by
alkynylation reaction in the presence of cis-(Tz)Pd(Cl)2(PPh3) adsorbing the cis-(Tz)Pd(Cl)2(PPh3) precatalyst onto silica gel
(Tz = 1,2,3-triazol-5-ylidene) as a precatalyst under 1.0 atm of and carrying out the reaction under heterogeneous conditions.
CO. Products resulting from competing Sonogashira coupling
Introduction
1,3-Diarylpropynones (ynones) are an important class of com-
pounds that are widely used in organic synthesis. They can
serve as electrophiles and Diels–Alder dienophiles[1–3] and are
crucial intermediates in the synthesis of several heterocyclic
compounds.[4] Recently, ynones that exhibit fluorescence emis-
Scheme 1. Commonly used methods for the synthesis of 1,3-diarylpropyn-
ones.
sion in the solid state have been reported as useful and impor-
tant organic materials for applications in photonics.[5,6]
Several methods have been reported for the synthesis of 1,3-
diarylpropynones.[7] Among these, stoichiometric reactions that
In view of the importance of fluorescent 1,3-diarylpropyn-
involve the treatment of aroyl chlorides with alkynylmetal com-
ones, we have investigated the synthesis of not only phenyl-
pounds (Scheme 1) have been widely used.[8] Alternatively, a
substituted derivatives but also 1-naphthyl, 1-pyrenyl, and 3-
catalytic carbonylative alkynylation reaction that involves
carbazolyl derivatives. N-Heterocyclic carbene–palladium com-
carbon monoxide as a one-carbon source is an attractive ap-
plexes have been widely used in organic synthesis as versatile
proach that has been studied as well.[9] This reaction involves
catalysts for C–C bond-forming reactions.[10] In the present
the palladium(0)-catalyzed carbonylation of aryl iodides in the
study, we employed a palladium complex that contains both
presence of carbon monoxide and terminal acetylenes
1,2,3-triazol-5-ylidene (Tz) and phosphine ligands for use in the
(Scheme 1). Despite tremendous advancements in catalytic
carbonylative alkynylation reaction. Herein we report the syn-
carbonylative alkynylation reactions for the synthesis of ynones,
thesis of fluorescent 1,3-diarylpropynones by employing a
this method has not been previously used for the synthesis of
carbonylative alkynylation reaction that is catalyzed by the cis-
(Tz)Pd(Cl)2(PPh3) (2) under 1.0 atm of CO. The solution and
fluorescent 1,3-diarylpropynones. There is one report, however,
for the synthesis of a pyrenyl-substituted ynone by using an
solid-state fluorescence of the ynones are reported, and the
electrophilic Friedel–Crafts acylation.[5] Most reports on carbon-
recovery and use of the active recycled catalyst has been dem-
ylative alkynylation reactions, however, deal with the synthesis
onstrated for up to three cycles.
of 1,3-diphenylpropynones that contain a variety substituted
phenyl rings. Moreover, a majority of the carbonylative alkynyl-
ation reactions reported so far have employed CO under high
pressure.[9]
Results and Discussion
Structures of palladium complexes that have been screened as
catalysts for carbonylative alkylation reactions are shown in Fig-
ure 1. Complexes 1–3 were synthesized (Scheme 2) by using
procedures similar to those reported for their imidazolylidene
analogues.[11] The synthesis of complex 4 has been previously
[a] Department of Chemistry, Indian Institute of Technology Madras,
Chennai 600036, India
E-mail: sanka@iitm.ac.in
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/ejoc.201600744.
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reported by our group.[12] Complexes 2 and 3 were prepared by
two different routes that proceed either through intermediate
acetonitrile complex 1 or through chloro-bridged dinuclear
complex 5 (Scheme 2). The treatment of 1 with triphenylphos-
phine in CH2Cl2 selectively afforded the corresponding cis iso-
mer 2, whereas treatment with tri(o-tolyl)phosphine selectively
gave the corresponding trans isomer 3. Results identical to
those above were obtained when 5 was treated with triphenyl-
phosphine and tri(o-tolyl)phosphine, respectively, to afford 2
1
and 3. The H NMR spectra of 2 and 3 obtained by these two
methods were superimposable, which clearly indicates the se-
lective formation of triphenylphosphine complex 2 or tri(o-
tolyl)phosphine complex 3. The structures and stereochemistry
of 1–3 were unambiguously assigned by single-crystal XRD
analysis (Figure 2).
Figure 2. ORTEP representation (50 % probability) of the crystal structures of
1 (top left), 2 (top right) and 3 (bottom).
Figure 1. Structure of palladium complexes 1–4 screened as catalysts in the
carbonylative alkynylation reaction.
ature. In polar solvents such as ethanol and acetonitrile, the
reactions did not proceed to yield the desired product, and only
starting materials were recovered. In 1,4-dioxane, 1,2-dimeth-
oxyethane, and 1,2-dichloroethane (i.e., solvents of moderate
polarity), the reaction did not reach completion after 24 h, and
the isolated yield of the corresponding ynone 7 was 51, 40, and
61 %, respectively. When the reaction was carried out in tolu-
ene, it went to completion within 18 h to give 7 in an isolated
yield of 81 %. In addition to 7, 1,4-diphenylbuta-1,3-diyne,
which resulted from the oxidative coupling of phenylacetylene,
was also formed as a byproduct. The Sonogashira coupling
product, namely 4-methyltolan, was not obtained in any of
these reactions. All of the subsequent reactions were carried
out in toluene at 80 °C.
Scheme 3. Carbonylative alkynylation reaction for the screening of solvents.
Table 1. Solvent screening for the carbonylative alkynylation reaction.
Entry
Solvent
Time [h]
Yield [%] of 7
1
2
3
4
5
6
CH3CN
C2H5OH
1,4-dioxane
24
24
24
24
24
18
no reaction
no reaction
Scheme 2. Synthesis of complexes 1–3.
51
40
61
81
1,2-dimethoxyethane
1,2-dichloroethane
toluene
Initially, we investigated the effect of solvent polarity on the
carbonylative alkynylation reaction by using complex 2 as the
catalyst and p-iodotoluene and phenylacetylene as substrates
(Scheme 3 and Table 1). The reactions were carried out in vari-
The catalytic reactivity of complexes 1–4 in the carbonylative
ous solvents at 80 °C, as there was no reaction at room temper- alkynylation reaction of phenylacetylene and 4-iodoanisole in
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toluene was studied. The course of the reaction over time was
monitored by removing an aliquot from the reaction mixture at
various intervals of time (up to 10 h) and then recording its
1H NMR spectrum. The methoxy proton signal of 4-iodoanisole
appeared at δ = 3.76 ppm, and that of the carbonylative alkyn-
ylation product 11 appeared at δ = 3.89 ppm with good base-
line separation in the 400 MHz 1H NMR spectra of the crude
product. The percentage conversion into 11 was calculated at
various time intervals, and the data obtained by using com-
plexes 2–4 as the catalysts are presented in Figure 3. The
carbonylative alkynylation reaction did not proceed with com-
plex 1, as the catalyst and starting materials were recovered
after a prolonged reaction time at 80 °C. When complex 4 was
used as the catalyst, 30 % conversion was achieved after 10 h,
whereas the reaction proceeded smoothly to an extent of 86 %
when complexes 2 and 3 were used as catalysts. The catalytic
activities of complexes 2 and 3 were nearly the same.
Figure 3. Comparison of the catalytic activity of complexes 2, 3, and 4 in the
carbonylative alkynylation reaction of 4-iodoanisole and phenylacetylene.
Complex 2 (5 mol-%) was used to investigate the scope of
the substrates for the carbonylative alkynylation, with specific
emphasis on the synthesis of ynones that not only are substi-
tuted phenyl derivatives but also are fluorophores such as 1-
naphthyl, 1-pyrenyl, and 3-carbazolyl derivatives. The results are
summarized in Scheme 4.
The products of the carbonylative alkynylation reaction,
namely the 1,3-diarylpropynones, were formed in good to ex-
cellent yields. In all of the reactions, the corresponding Sonoga-
shira coupling product, that is the diarylethyne, was not formed
in even trace amounts.[13] This indicates that the carbonylation
step is much faster than that of the Sonogashira coupling. Small
amounts (<10 %) of the 1,4-diarylbuta-1,3-diynes, however,
were observed, presumably from the oxidative dimerization of
Scheme 4. Synthesis of 1,3-diarylpropynones through a carbonylative alkynyl-
ation reaction catalyzed by complex 2.
After the synthesis of a variety of fluorescent ynones, we
the excess amounts of the terminal acetylenes. The carbonyl- focused our attention on recovering and recycling the catalyst.
ated products 6–28 were easily isolated by a chromatography Complex 2 was initially adsorbed onto an excess amount of
on silica gel, and the reported yields are that of the pure prod- silica gel (100–200 mesh; 0.025 mmol on 1 g of silica gel, 5 mol-
uct after chromatography. Notably, regioisomeric ynones 12 % Pd relative to the substrate), and the carbonylative alkynyl-
and 15 as well as 20 and 23 are easily accessible by this ation reaction of iodobenzene and (3-methoxyphenyl)acetylene
method. All of the compounds were thoroughly characterized was carried out in toluene at 80 °C in the presence of Et3N
by spectroscopic methods.
(Scheme 5 and Table 2). The reaction was equally efficient on
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silica gel (i.e., under heterogeneous conditions)[14] and reached in their absorption and emission spectra. Pyrene derivatives 23
completion in 18 h to give 6 in 92 % yield. These results are and 27 were emissive in the solid state as well. The emission
comparable to those of the carbonylative alkynylation reactions spectra of these derivatives as neat solids are shown in Figure 5.
that were carried out under homogeneous conditions The excimer emission band (approximately 583–590 nm) of
(Scheme 4). Upon completion of the reaction, the mixture (i.e., these derivatives was more prominent than the monomer band
toluene layer) was removed by a syringe, and the residue, which in the solid-state spectra compared with those of the solution
was presumably the active catalyst adsorbed onto the silica gel, spectra. The emission bands were bathochromically shifted by
was rinsed with toluene. The residue was reused as the catalyst approximately 0.20 eV in the solid state compared with those
in subsequent cycles of the carbonylative alkynylation reaction. of the solution spectra. The quantum yield of fluorescence (Φf)
This recovered catalyst was used for up to three cycles to give was measured for compounds 20–28 by using quinine sulfate
6 in the second and third cycle of 85 % (after 22 h) and 78 % as the reference (Supporting Information) and was found to be
(after 27 h), respectively (Table 2). We also carried out a hot in the range of 0.08–0.12 for phenylethynyl pyrene derivatives
filtration test, in which the Pd-coated silica was separated from 20–25 and in the range of 0.42–0.43 for naphthyl- and carb-
the reaction mixture, and the filtrate was further used for the azolyl-substituted pyrene derivatives 27 and 28, respectively.
reaction under reaction conditions similar to those described
above. No significant reaction progress, however, was observed
over the prolonged period of time. Pd had leached into the
toluene layer after each catalytic cycle according to inductively
coupled plasma-optical emission spectrometry (ICP-OES). The
Pd content in the toluene layer was found to be 0.98 ppm (aver-
age of three estimations), and only 0.2 wt.-% of Pd leached out
of the reaction mixture during each cycle. On the basis of the
above analysis, we concluded that precatalyst 2 and the acti-
vated catalyst, which was formed during the reaction, are
strongly adsorbed onto the surface of silica gel.
Figure 4. Absorption (left) and fluorescence spectra (λex = 370 nm) of regio-
isomeric ynones 20 and 23 along with ynones 27 and 28 in acetonitrile
(10–5
M).
Scheme 5. Carbonylative alkynylation reaction used to demonstrate the re-
covery and recycling of the catalyst.
Table 2. Recovery and recycling of catalyst by using silica gel support.
Cycle
Time [h]
Yield [%] 6
1
2
3
18
22
27
92
85
78
The electronic absorption and fluorescence emission spectra
of carbazolyl ynones 17 and 19 along with the nine pyrenyl
ynones 20–28 were recorded in CH3CN (10–5
M; Figure 4; Sup-
porting Information). In a comparison of pyrene, carbazole, and
naphthalene, all of which absorb and emit in the UV region,[15]
the absorption and fluorescence emission bands of the pyrenyl
ynones were bathochromically shifted by 1.1–1.3 eV as a result
of the extended conjugation. The absorption bands in the re-
gion of 350–450 nm are essentially from the pyrene chromo-
Figure 5. Emission spectra of 23 and 27 in the solid state (λex = 372 nm).
phore.[16] At a concentration of 10–5
M, the emission band in the
region of 450–550 nm is largely the result of pyrene monomer
emission[15] with a weak shoulder beyond 550 nm, which could
be from the excimer emission.[16] Notably, the emission from
Conclusions
some of these multichromophoric ynones (i.e., 27 and 28) es- The synthesis of several 1,3-diarylpropynones has been accom-
sentially covers most of the visible region (450–650 nm). Regio- plished by a carbonylative alkynylation reaction using a (phos-
isomeric ynones 20 and 23 did not exhibit any large difference phine)(1,2,3-triazol-5-ylidene)palladium complex as a catalyst
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1424, 1363, 1327, 1281, 1227, 1192, 1152, 1124, 1042, 1010 cm–1
.
under 1.0 atm of CO. The products were obtained in good to
excellent yields. Several fluorescent ynones that contain 1-
naphthyl, 1-pyrenyl, and 3-carbazolyl chromophores have been
synthesized for the first time by using this catalytic carbonyl-
ation method. The reactions were very clean, as the usual by-
products that could arise from a competing Sonogashira cou-
pling reaction were not observed. This indicates that the carb-
onylation reaction proceeded much faster than the Sonogashira
HRMS (ESI): calcd. for C23H16INO2 [M + H]+ 466.0304; found
466.0300.
1-(9-Methyl-9H-carbazol-3-yl)-3-(naphthalen-1-yl)prop-2-yn-1-
one (19): The carbonylative alkynylation reaction between 3-iodo-
9-methyl-9H-carbazole (100 mg, 0.33 mmol) and 1-ethynylnaphth-
alene (70 μL, 0.49 mmol) in the presence of triethylamine (0.13 mL,
0.98 mmol) and complex 2 (11 mg, 0.02 mmol) gave 19 (98 mg,
coupling under these reaction conditions. The feasibility of the 84 %) as a yellow-orange solid; m.p. 95 °C. 1H NMR (500 MHz,
CDCl3): δ = 9.10 (d, J = 1 Hz, 1 H), 8.54 (d, J = 9 Hz, 1 H), 8.46 (dd,
J = 9, 2 Hz, 1 H), 8.18 (d, J = 8 Hz, 1 H), 8.02–7.98 (m, 2 H), 7.93 (d,
J = 9 Hz, 1 H), 7.71–7.68 (m, 1 H), 7.62–7.59 (m, 1 H), 7.57–7.53 (m,
2 H), 7.47 (t, J = 9 Hz, 2 H), 7.34 (dt, J = 8, 1 Hz, 1 H), 3.91 (s, 3 H)
ppm. 13C NMR (125 MHz, CDCl3): δ = 177.7, 144.6, 141.9, 133.9,
133.3, 133.0, 131.2, 129.2, 128.7, 127.85, 127.82, 127.7, 127.0, 126.9,
126.1, 125.4, 123.7, 123.2, 123.0, 120.8, 120.5, 118.4, 109.3, 108.4,
recovery and recycling of the catalyst was demonstrated by us-
ing silica gel as a solid support to anchor the catalyst precursor.
The fluorescent ynones exhibit emission not only in the solution
state but also in the solid state, which make them potential
candidates for application as organic photonic materials.
92.3, 90.5, 29.5 ppm. IR (KBr): ν = 3058, 2926, 2851, 2194, 1617,
˜
1588, 1499, 1472, 1395, 1363, 1321, 1249, 1195 cm–1. HRMS (EI):
calcd. for C26H17NO 359.1310; found 359.1312.
Experimental Section
General Procedure for the Carbonylative Alkynylation Reaction:
Complex 2 (5 mol-%) was added to an oven-dried Schlenk flask
under nitrogen. Dry toluene (5 mL) was added to the flask followed
by triethylamine (3 equiv.) and then the aryl iodide (1 equiv.). Fi-
nally, arylacetylene (1.5 equiv.) was added to the reaction mixture,
and the reaction flask was flushed with a balloon filled with CO
(2 ×). The reaction mixture was stirred under CO (balloon) at 80 °C
for 18–24 h. The crude reaction mixture was extracted with ethyl
acetate. The organic layer was washed with brine solution, dried
with sodium sulfate, and concentrated under vacuum. The crude
reaction mixture was purified by column chromatography (hexane
and ethyl acetate). CCDC 1476176 (for 1), 1415599 (for 2), and
1415600 (for 3) contain the supplementary crystallographic data for
this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre.
3-Phenyl-1-(pyren-1-yl)prop-2-yn-1-one (20):[5] The carbonylative
alkynylation reaction between iodopyrene (100 mg, 0.30 mmol) and
phenylacetylene (50 μL, 0.46 mmol) in the presence of triethylamine
(0.12 mL, 0.91 mmol) and complex 2 (10 mg, 0.01 mmol) gave 20
(73 mg, 72 %) as a yellow solid; m.p. 110 °C. 1H NMR (400 MHz,
CDCl3): δ = 9.53 (d, J = 9 Hz, 1 H), 9.00 (dd, J = 8, 1 Hz, 1 H), 8.29–
8.17 (m, 5 H), 8.08–8.04 (m, 2 H), 7.75 (d, J = 7 Hz, 2 H), 7.52–7.43
(m, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 180.0, 135.3, 133.1,
131.5, 130.9, 130.7, 130.7, 130.6, 130.5, 128.8, 127.2, 127.0, 126.7,
126.5, 124.9, 124.1, 120.6, 92.4, 89.3 ppm. IR (KBr): ν = 3050, 2918,
˜
2847, 2194, 1755, 1630, 1613, 1591, 1499, 1484, 1438, 1380, 1317,
1273, 1202, 1117, 1067 cm–1. HRMS (EI): calcd. for C25H14O 330.1045;
found 330.1040.
1-(Pyren-1-yl)-3-[3-(trifluoromethyl)phenyl]prop-2-yn-1-one
(21): The carbonylative alkynylation reaction between iodopyrene
(100 mg, 0.30 mmol) and 1-ethynyl-3-(trifluoromethyl)benzene
(66 μL, 0.46 mmol) in the presence of triethylamine (0.12 mL,
0.91 mmol) and complex 2 (10 mg, 0.02 mmol) gave 21 (69 mg,
57 %) as a yellow-orange solid; m.p. 128 °C. 1H NMR (400 MHz,
CDCl3): δ = 9.57 (d, J = 9 Hz, 1 H), 9.03 (d, J = 8 Hz, 1 H), 8.36–8.25
(m, 5 H), 8.14–8.09 (m, 2 H), 8.00 (s, 1 H), 7.92 (d, J = 8 Hz, 1 H),
7.75 (d, J = 8 Hz, 1 H), 7.60 (t, J = 8 Hz, 1 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 179.6, 136.0, 135.7, 131.7, 131.2, 131.1, 131.1, 131.0,
129.7, 129.7, 129.4, 129.0, 127.32, 127.30, 127.1, 127.1, 127.0, 126.7,
3-(3-Methoxyphenyl)-1-(9-methyl-9H-carbazol-3-yl)prop-2-yn-
1-one (17): The carbonylative alkynylation reaction between 3-
iodo-9-methyl-9H-carbazole (100 mg, 0.33 mmol) and 1-ethynyl-3-
methoxybenzene (62 μL, 0.49 mmol) in the presence of triethyl-
amine (0.13 mL, 0.98 mmol) and complex 2 (11 mg, 0.02 mmol)
gave 17 (97 mg, 88 %) as a yellow solid; m.p. 121 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.94 (m, 1 H), 8.34 (dd, J = 8, 2 Hz, 1 H), 8.12
(dd, J = 8, 1 Hz, 1 H), 7.53–7.49 (m, 1 H), 7.42–7.39 (m, 2 H), 7.33–
7.28 (m, 3 H), 7.23–7.22 (m, 1 H), 7.03–7.00 (m, 1 H), 3.86 (s, 3 H),
3.84 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 177.6, 159.6, 144.6,
141.9, 129.9, 129.0, 127.9, 126.8, 125.5, 123.4, 123.2, 122.9, 121.7,
120.8, 120.5, 117.7, 117.3, 109.2, 108.3, 92.1, 87.3, 55.5, 29.5 ppm. IR
125.0, 124.9, 124.2, 124.1, 121.7, 89.97, 89.94 ppm. IR (KBr): ν = 2954,
˜
2918, 2855, 2358, 2198, 1737, 1630, 1591, 1502, 1430, 1331, 1263,
1120, 1073, 1002 cm–1. HRMS (EI): calcd. for C26H13F3O 398.0918;
found 398.0915.
(KBr): ν = 3061, 3004, 2933, 2832, 2194, 1766, 1619, 1588, 1481,
˜
1430, 1363, 1327, 1252, 1220, 1128, 1042, 1021 cm–1. HRMS (EI):
calcd. for C23H17NO2 339.1259; found 339.1252.
1-(6-Iodo-9-methyl-9H-carbazol-3-yl)-3-(3-methoxyphenyl)- 3-(3-Methoxyphenyl)-1-(pyren-1-yl)prop-2-yn-1-one (22): The
prop-2-yn-1-one (18): The carbonylative alkynylation reaction be-
tween 3,6-diiodo-9-methyl-9H-carbazole (100 mg, 0.23 mmol) and
1-ethynyl-3-methoxybenzene (44 μL, 0.35 mmol) in the presence of
triethylamine (96 μL, 0.70 mmol) and complex 2 (8 mg, 0.01 mmol)
gave 18 (63 mg, 59 %) as a yellow solid; m.p. 106 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.86 (d, J = 1 Hz, 1 H), 8.43 (d, J = 6 Hz, 1 H),
8.35 (dd, J = 8, 2 Hz, 1 H), 7.76 (dd, J = 9 Hz, 1 H), 7.42–7.34 (m, 3
H), 7.25–7.19 (m, 2 H), 7.06–7.04 (m, 1 H), 3.87 (s, 3 H), 3.83 (s, 3 H)
ppm. 13C NMR (100 MHz, CDCl3): δ = 177.4, 159.6, 144.4, 141.0,
135.1, 129.9, 129.6, 129.4, 128.2, 125.6, 123.8, 121.61, 121.5, 117.6,
117.6, 117.4, 111.2, 108.6, 92.4, 90.1, 83.2, 55.6, 29.6 ppm. IR (KBr):
carbonylative alkynylation reaction between 1-iodopyrene (100 mg,
0.30 mmol) and 1-ethynyl-3-methoxybenzene (58 μL, 0.46 mmol) in
the presence of triethylamine (0.12 mL, 0.91 mmol) and complex 2
(10 mg, 0.02 mmol) gave 22 (99 mg, 90 %) as a yellow solid; m.p.
1
112 °C. H NMR (500 MHz, CDCl3): δ = 8.64 (d, J = 9 Hz, 1 H), 8.51
(d, J = 8 Hz, 1 H), 8.31–8.23 (m, 4 H), 8.16 (t, J = 9 Hz, 2 H), 8.08–
8.05 (m, 2 H), 7.52 (t, J = 7 Hz, 1 H), 7.45 (t, J = 7 Hz, 1 H), 7.34 (d,
J = 7 Hz, 1 H), 2.76 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
180.0, 140.6, 136.2, 133.8, 133.2, 133.1, 133.0, 132.4, 131.2, 131.1,
131.0, 129.67, 129.61, 127.3, 126.7, 126.6, 126.4, 126.1, 125.2, 124.7,
124.4, 114.3, 94.2, 91.7, 22.1 ppm. IR (KBr): ν = 2958, 2926, 2832,
˜
ν = 3058, 2958, 2922, 2854, 2194, 1712, 1616, 1580, 1481, 1445,
˜
2190, 1634, 1613, 1591, 1499, 1484, 1459, 1363, 1313, 1260, 1117,
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1046, 1010 cm–1. HRMS (EI): calcd. for C26H16O2 360.1150; found
360.1148.
(13 mg, 0.02 mmol) gave 27 (132 mg, 0.35 mmol, 88 %) as a yellow-
orange solid; m.p. 141 °C. 1H NMR (400 MHz, CDCl3): δ = 9.31 (d,
J = 8 Hz, 1 H), 8.82 (dd, J = 7, 1 Hz, 1 H), 8.62 (d, J = 9 Hz, 1 H),
8.31–8.03 (m, 9 H), 7.94 (d, J = 8 Hz, 1 H), 7.74–7.59 (m, 3 H) ppm.
13C NMR (100 MHz, CDCl3): δ = 179.9, 135.1, 134.3, 134.1, 133.8,
133.6, 133.1, 131.1, 130.9, 129.6, 129.5, 129.0, 128.7, 127.2, 126.9,
126.6, 126.5, 126.4, 126.2, 125.1, 124.7, 124.6, 124.4, 124.0, 114.2,
1-Phenyl-3-(pyren-1-yl)prop-2-yn-1-one (23): The carbonylative
alkynylation reaction between iodobenzene (100 mg, 0.49 mmol)
and 1-ethynylpyrene (167 mg, 0.76 mmol) in the presence of trieth-
ylamine (0.20 mL, 1.47 mmol) and complex 2 (17 mg, 0.02 mmol)
gave 23 (147 mg, 91 %) as a yellow solid; m.p. 170 °C. 1H NMR
(500 MHz, CDCl3): δ = 8.66 (d, J = 9 Hz, 1 H), 8.38 (d, J = 7 Hz, 2 H),
8.33 (d, J = 8 Hz, 1 H), 8.29–8.25 (m, 3 H), 8.17 (t, J = 8 Hz, 2 H),
8.08–8.05 (m, 2 H), 7.68 (t, J = 7 Hz, 1 H), 7.59 (t, J = 7 Hz, 2 H) ppm.
13C NMR (125 MHz, CDCl3): δ = 178.2, 137.4, 134.2, 133.8, 133.3,
131.3, 131.2, 130.9, 129.8, 129.7, 128.8, 127.2, 126.7, 126.6, 126.5,
94.3, 91.7 ppm. IR (KBr): ν = 2958, 2918, 2847, 2190, 1634, 1509,
˜
1430, 1327, 1281, 1249, 1216, 1174, 1131, 1103, 1070 cm–1. HRMS
(EI): calcd. for C29H16O 380.1201; found 380.1205.
1-(9-Methyl-9H-carbazol-3-yl)-3-(pyren-1-yl)prop-2-yn-1-one
(28): The carbonylative alkynylation reaction between 3-iodo-9-
methyl-9H-carbazole (100 mg, 0.33 mmol) and 1-ethynylpyrene
(110 mg, 0.49 mmol) in the presence of triethylamine (0.13 mL,
0.98 mmol) and complex 2 (11 mg, 0.02 mmol) gave 28 (117 mg,
0.27 mmol, 83 %) as a yellow-orange solid; m.p. 189 °C. 1H NMR
(500 MHz, CDCl3): δ = 9.15 (d, J = 1 Hz, 1 H), 8.77 (d, J = 9 Hz, 1 H),
8.51 (dd, J = 8, 1 Hz, 1 H), 8.37 (d, J = 8 Hz, 1 H), 8.30–8.24 (m, 3
H), 8.21–8.16 (m, 3 H), 8.09–8.07 (m, 2 H), 7.56 (t, J = 8 Hz, 1 H),
7.50–7.45 (m, 2 H), 7.35 (t, J = 8 Hz, 1 H), 3.91 (s, 3 H) ppm. 13C
NMR (125 MHz, CDCl3): δ = 177.7, 144.5, 141.9, 133.7, 133.0, 131.2,
131.2, 131.0, 129.5, 129.3, 127.9, 127.3, 126.9, 126.7, 126.5, 126.4,
125.3, 124.7, 124.5, 124.2, 123.6, 123.2, 123.0, 120.8, 120.5, 114.7,
125.1, 124.7, 124.4, 124.1, 114.1, 92.9, 92.7 ppm. IR (KBr): ν = 3058,
˜
2922, 2855, 2194, 1613, 1588, 1495, 1474, 1438, 1395, 1359, 1321,
1256, 1202, 1141, 1120 cm–1. HRMS (EI): calcd. for C25H14O 330.1045;
found 330.1040.
3-(Pyren-1-yl)-1-(o-tolyl)prop-2-yn-1-one (24): The carbonylative
alkynylation reaction between o-iodotoluene (100 mg, 0.45 mmol)
and 1-ethynylpyrene (154 mg, 0.68 mmol) in the presence of trieth-
ylamine (0.19 mL, 1.36 mmol) and complex 2 (15 mg, 0.02 mmol)
gave 24 (105 mg, 0.30 mmol, 67 %) as a light yellow solid; m.p.
1
115 °C. H NMR (500 MHz, CDCl3): δ = 8.61 (d, J = 9 Hz, 1 H), 8.51
(dd, J = 8, 1 Hz, 1 H), 8.29–8.21 (m, 4 H), 8.16–8.11 (m, 2 H), 8.07–
8.04 (m, 2 H), 7.51 (dt, J = 7, 1 Hz, 1 H), 7.45 (t, J = 7 Hz, 1 H), 7.34
(d, J = 7 Hz, 1 H), 2.76 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ =
180.0, 140.6, 132.2, 133.8, 133.2, 133.1, 133.0, 132.4, 131.19, 131.15,
130.9, 129.6, 129.5, 127.2, 126.7, 126.5, 126.4, 126.1, 125.1, 124.6,
109.3, 108.4, 93.3, 91.8, 29.6 ppm. IR (KBr): ν = 2922, 2855, 2180,
˜
1613, 1588, 1470, 1430, 1359, 1321, 1267, 1117, 1002 cm–1. HRMS
(EI): calcd. for C32H19NO 433.1467; found 433.1467.
Supporting Information (see footnote on the first page of this
1
article): Characterization data, copies of H and 13C NMR spectra of
124.4, 124.1, 114.3, 94.2, 91.7, 22.1 ppm. IR (KBr): ν = 3044, 2958,
˜
all new compounds.
2918, 2847, 2173, 1627, 1594, 1566, 1487, 1455, 1430, 1306, 1270,
1206, 1124, 1010 cm–1. HRMS (EI): calcd. for C26H16O 344.1201;
found 344.1200.
Acknowledgments
1-(4-Methoxyphenyl)-3-(pyren-1-yl)prop-2-yn-1-one (25): The
carbonylative alkynylation reaction between 4-iodoanisole (100 mg,
0.43 mmol) and 1-ethynylpyrene (145 mg, 0.64 mmol) in the pres-
ence of triethylamine (0.17 mL, 1.28 mmol) and complex 2 (14 mg,
0.02 mmol) gave 25 (122 mg, 79 %) as a yellow solid; m.p. 172 °C.
1H NMR (500 MHz, CDCl3): δ = 8.67 (d, J = 9 Hz, 1 H), 8.36–8.25 (m,
6 H), 8.19–8.17 (m, 2 H), 8.10–8.06 (m, 2 H), 7.06 (d, J = 9 Hz, 2 H),
3.94 (s, 3 H) ppm. 13C NMR (125 MHz, CDCl3): δ = 176.8, 164.6, 133.7,
133.1, 132.1, 131.25, 131.21, 131.0, 130.81, 129.66, 129.62, 127.3,
126.7, 126.6, 126.4, 125.2, 124.7, 124.5, 124.1, 114.4, 114.1, 92.7, 92.0,
55.7 ppm. IR (KBr): 2962, 2922, 2851, 2194, 1613, 1588, 1502, 1481,
1323, 1252, 1224, 1117 cm–1. HRMS (EI): calcd. for C26H16O2
360.1150; found 360.1146.
A. D. thanks the Council of Scientific and Industrial Research
(CSIR) for a fellowship. S. S. thanks the Department of Science
and Technology (DST), New Delhi for the financial support (re-
search grant no. SR/S1/OC-61/2011) and the Department of
Chemistry and the Sophisticated Analytical Instrument Facility,
Indian Institute of Technology (SAIF, IIT) Madras for the infra-
structure.
Keywords: Synthetic methods · Palladium · Alkynylation ·
Carbonylation · Ynones · Fluorescence
3-(Pyren-1-yl)-1-(p-tolyl)prop-2-yn-1-one (26): The carbonylative
alkynylation reaction between 4-iodotoluene (100 mg, 0.45 mmol)
and 1-ethynylpyrene (154 mg, 0.68 mmol) in the presence of trieth-
ylamine (0.19 mL, 1.36 mmol) and complex 2 (15 mg, 0.02 mmol)
gave 26 (128 mg, 82 %) as a yellow solid; m.p. 149 °C. 1H NMR
(400 MHz, CDCl3): δ = 8.67 (d, J = 9 Hz, 1 H), 8.34–8.25 (m, 6 H),
8.19–8.16 (m, 2 H), 8.09–8.05 (m, 2 H), 7.38 (d, J = 8 Hz, 2 H), 2.49
(s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 177.9, 145.3, 135.1,
133.7, 133.2, 131.29, 131.22, 131.0, 129.9, 129.7, 129.65, 129.62,
127.3, 126.7, 126.6, 126.5, 125.2, 124.7, 124.4, 124.1, 114.2, 92.8, 92.4,
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Received: June 17, 2016
Published Online: ■
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Full Paper
Carbonylative Alkynylation
A Pd–N-heterocyclic carbene (Pd–NHC)
complex has been used as the catalyst
in a carbonylative alkynylation reac-
tion that afforded several fluorescent
1,3-diarylpropynones in high yields.
A. Dasgupta, V. Ramkumar,
S. Sankararaman* .............................. 1–8
Synthesis of Fluorescent 1,3-Diaryl-
propynones by Carbonylative Alk-
ynylation Reaction Using (Phos-
phine) (1,2,3-triazol-5-ylidene)palla-
dium Complexes as Catalysts
DOI: 10.1002/ejoc.201600744
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim