Hydroarylation of unsaturated carbon-carbon bonds in cross-conjugated enynones under the action of superacid CF3SO3H or acidic zeolite HUSY. Reaction mechanism and DFT study on cationic intermediate species

Article abstract of DOI:10.1039/c8ob01985a

Reactions of cross-conjugated enynones,1,5-diarylpent-1-en-4-yn-3-ones, with arenes in the system TfOH-pyridine or under the action of acidic zeolite HUSY lead regioselectively to products of hydroarylation of the acetylene bond only,1,1,5-triarylpent-1,4-dien-3-ones, in yields up to 98%. These dienones add one more arene molecule to the double carbon-carbon bond in neat TfOH forming 1,1,5,5-tetraarylpent-1-en-3-ones in high yields. Cationic reaction intermediates have been studied by means of DFT calculations to elucidate plausible reaction mechanisms.

Full text of DOI:10.1039/c8ob01985a

Organic &
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Hydroarylation of unsaturated carbon–carbon
bonds in cross-conjugated enynones under the
action of superacid CF3SO3H or acidic zeolite
HUSY. Reaction mechanism and DFT study on
cationic intermediate species†
Cite this: Org. Biomol. Chem., 2018,
16, 7891
Maiia I. Aleksandrova,a Stanislav V. Lozovskiy,a Steve Saulnier,a
a,c
Alexander A. Golovanov,b Irina A. Boyarskayaa and Aleksander V. Vasilyev
*
Reactions of cross-conjugated enynones,1,5-diarylpent-1-en-4-yn-3-ones, with arenes in the system
TfOH-pyridine or under the action of acidic zeolite HUSY lead regioselectively to products of hydroaryla-
tion of the acetylene bond only,1,1,5-triarylpent-1,4-dien-3-ones, in yields up to 98%. These dienones
add one more arene molecule to the double carbon–carbon bond in neat TfOH forming 1,1,5,5-tetraaryl-
pent-1-en-3-ones in high yields. Cationic reaction intermediates have been studied by means of DFT
calculations to elucidate plausible reaction mechanisms.
Received 15th August 2018,
Accepted 3rd October 2018
DOI: 10.1039/c8ob01985a
rsc.li/obc
hydropyran-4-ones II under the acidic reaction conditions
Introduction
(Scheme 1).8
Various conjugated enynones are widely used in organic syn-
Based on previous work8 and our general research on super-
thesis. The presence of three reaction centers in the structure electrophilic activation of alkynes, alkenes and allenes,9 we
of these compounds, namely, carbon atoms of double and undertook a special study on reactions of 1,5-diarylpent-1-en-4-
triple bonds and carbonyl group, allows the construction of yn-3-ones 1 with arenes under the action of acids. At the acid
various carbo- or heterocycles1–3 and analogues of natural promoted interaction of enynones 1 with arenes, one may
compounds.4,5 In particular, addition of S-nucleophiles to expect a hydroarylation of both triple and double carbon–
cross-conjugated enynones takes place mainly at the acetylene carbon bonds leading to the formation of various compounds
bond, which further leads to the formation of substituted thio- (Scheme 2).
pyranes.6 These enynones have a great synthetic utility for
medicinal chemistry research.7
The main goals of this work were the investigation of regio-
and stereo-selectivities of hydroarylation of 1,5-diarylpent-1-en-
Very recently we have shown that cross-conjugated eny- 4-yn-3-ones 1 by arenes under the action of Brønsted acids or
nones, 1,5-diarylpent-1-en-4-yn-3-ones 1, undergo addition of acidic zeolite and the study of the reaction cationic intermedi-
triflic acid (CF3SO3H, TfOH) or sulfuric acid (H2SO4) to the ates by quantum chemical calculations (DFT method).
acetylene bond with the formation of vinyl triflates or sulfates
It should be specially mentioned that acidic zeolites are
I, correspondingly, which are further cyclized into 2,6-diaryldi- widely and effectively explored as electrophilic activators in
reactions of organic compounds.10 Compared to the conven-
tional Brønsted (super)acids (H2SO4, TfOH, FSO3H, HF, etc.),
the use of zeolites is much more ecologically friendly and they
are easily recyclable.10
aDepartment of Organic Chemistry, Institute of Chemistry, Saint Petersburg State
University, Universitetskaya nab. 7/9, Saint Petersburg, 199034, Russia
bDepartment of Chemistry, Chemical Processes and Technologies, Togliatti State
University, Belorusskaya ul. 14, Togliatti, 445667, Russia
cDepartment of Chemistry, Saint Petersburg State Forest Technical University,
Institutsky per. 5, Saint Petersburg, 194021, Russia. E-mail: aleksvasil@mail.ru,
a.vasilyev@spbu.ru; http://chem.spbu.ru/research/nauchnye-gruppy/237-scientific-
activities/research-groups/951-vasilev.html
†Electronic supplementary information (ESI) available: Copies of 1H, 13C, 19F
NMR spectra of compounds; X-ray data; data of DFT calculations. CCDC
1847444, 1847451, 1847452, 1847453, 1847454 and 1847456. For ESI and crystal-
lographic data in CIF or other electronic format see DOI: 10.1039/c8ob01985a
Scheme 1 Brønsted acid-promoted cyclization of 1,5-diarylpent-1-en-
4-yn-3-ones 1 into 2,6-diaryldihydropyran-4-ones II through the inter-
mediate formation of vinyl triflates or sulfates I (data from ref. 8).
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oxygen that affords cation A1. Then, protonation of the
carbon–carbon triple or double bonds may take place leading
to species B1 or C1, respectively, both of which may be further
protonated to trication D1. Calculations of Gibbs free energies
of these protonation reactions showed that the formation of
cation A1 is very favorable energetically with ΔG298 −94.3
kJ mol−1 (see reaction ΔG298 values in scheme in Table 2). The
second protonation, which leads to species B1 and C1, is
unfavourable. However, the formation of cation B1 is less
unfavourable. Formation of B1 in two protonation steps is
thermodynamically possible with a value of ΔG298 = −94.3 +
Scheme 2 Possible ways of acid promoted hydroarylation of triple and
double bonds in enynones 1.
22.8 = −71.5 kJ mol−1. For C1, this value is higher, ΔG298
=
Results and discussion
−94.3 + 48.4 = −45.9 kJ mol−1. Trication D1 is very high in
energy (see high positive ΔG298 values of the corresponding
reactions). From these data, one may conclude that the second
protonation, most probably, should rather take place on the
triple bond than on the double one for cross-conjugated
enynones.
Starting cross-conjugated pent-1-en-4-yn-3-ones 1a–m bearing
aryl or hetaryl rings with various donor–acceptor substituents
were synthesized by Claisen–Schmidt condensation of the
corresponding 4-arylbut-3-yn-2-ones and aromatic (or hetero-
aromatic) aldehydes (Table 1).
First we considered possible ways of protonation of
1,5-diphenylpent-1-en-4-yn-3-one 1a. The protonation of 1a
may proceed in several consecutive steps (Table 2 and scheme
in it). A first proton is bonded to the more basic carbonyl
Charge distribution, contribution of the atomic orbital to
the LUMO and global electrophilicity indices ω (ref. 11) of
species A1, B1, C1, and D1 were calculated by the DFT
method. Compared to cation A1, dication B1 and C1 have
Table 1 Synthesis of starting cross-conjugated enynones 1a–m used in this study
Enynone
1a
1b
1c
1d
1e
1f
1g
1h
Ar
Ph
Ph
4-MeC6H4
Ph
4-MeOC6H4
Ph
Ph
4-MeC6H4
Ph
Ph
4-ClC6H4
Ph
4-FC6H4
Ph
3-FC6H4
Ar′(or Hetaryl)
4-NO2C6H4
Enynone
1i
1j
1k
1l
1m
Ar
Ph
2-FC6H4
Ph
Ph
Ph
Ph
Ar′(or Hetaryl)
2,4-F2C6H3
5-Bromofuran-2-yl
Thiophen-2-yl
4-MeOC6H4
Table 2 Selected electronic characteristics (DFT calculations) of cations A1, B1, C1, and D1 derived from protonation of enynone 1a, and calculated
Gibbs energies ΔG298 of protonation reactions
Cation
EHOMO, eV
ELUMO, eV
ωa, eV
q (C1)b, e
q (C3)b, e
q (C5)b, e
k (C1)LUMO c, %
k (C3)LUMO c, %
k (C5)LUMO c, %
1a
−7.02
−7.41
−8.05
−8.25
−9.04
−2.75
−4.04
−4.93
−4.78
−5.92
2.8
4.9
6.8
6.1
6.7
−0.06
0.04
0.09
0.20
0.18
0.49
0.23
0.54
0.34
0.74
0.08
−0.33
0.43
−0.24
0.54
18.3
21.7
0.5
25.2
0.5
14.6
24.0
5.8
5.5
11.2
14.5
15.3
18.4
3.2
A1
B1
C1
D1
19.8
a Global electrophilicity index ω = (EHOMO + ELUMO)2/8(ELUMO − EHOMO). b Natural charges. c Contribution of the atomic orbital to the molecular
orbital.
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higher values of electrophilicity indices and they may be con-
sidered as strong electrophiles.12,13
The comparison of the charge distributions in species A1,
B1, and C1 reveals that carbon C3 bears a large part of positive
charge (Table 2). Among these three species, dication B1 has
the largest charge on C5 (0.43e) and the highest contribution
(18.4%) in the LUMO as well. These data show a coincidence
of charge and orbital control in the reactivity of carbon C5 in
species B1. Thus, both calculated thermodynamic parameters
(ΔG298 of reactions) and electronic characteristics (Table 2)
indicate that vinyl type dications B, with an electrophilic
centre on carbon C5, are presumably the reactive species
derived from cross-conjugated enynones 1 under their proto-
nation in Brønsted superacids.
Then, reactions of enynone 1a with benzene promoted by
different Brønsted and Lewis acids were explored (Table 3).
The reaction with an excess of benzene (11 equiv.) in TfOH for
1 h afforded quantitatively compound 2a as a product of
hydrophenylation of both triple and double bonds of 1a
(entry 1), while the use of 1 equiv. of benzene gave a more
complex mixture of products (entry 2). The use of H2SO4 was
not effective to obtain hydrophenylation product 2a in high
yield: the main reaction products were Ia and IIa (entries 3
and 4), which formation was already observed and discussed
in our previous work.8 Also, Lewis acid AlCl3 did not give good
results (entries 5 and 6). Thus, TfOH was found to be the best
acid for carrying out hydroarylation of unsaturated bonds in
enynones 1.
Then, reactions of other compounds 1 with benzene in
TfOH were carried out (Scheme 3). Enynone 1b gave the
addition product of benzene to each unsaturated bond as a
mixture of E-/Z-isomers of enone 2b in a yield of 34%.
Reactions of enynones 1d,f,m bearing 4-methyl, 4-chloro, or
4-methoxy groups in the aryl ring at the double bond resulted
in the quantitative formation of compound 2a. The latter one
was formed by addition of benzene to both triple and double
bonds followed by exchange of the aryl group for a phenyl one.
The same exchange was observed previously by us for reactions
of other arylalkenes in Brønsted superacids.14,15
Scheme 3 Reactions of enynones 1b,d,e,f,g, and m with benzene in
TfOH at room temperature.
withdrawing 4-fluorophenyl group hampers, to some extent,
this exchange. However, reaction took 2 h to achieve complete
conversion of starting 1g. On the other hand, enynone 1e
having a powerful acceptor 4-nitrophenyl ring at the double
bond afforded only a product of addition to the triple bond,
dienone 3a (Scheme 3). No addition of benzene to such de-
activated double bonds occurred.
Based on our experience on suppression of such aryl group
exchange,14,15 we tried to avoid this process in reactions of eny-
nones 1 by lowering the reaction temperature. However,
decreasing temperature down to −40 °C in TfOH for enynones
1d,m bearing strong donating substituents (4-MeC6H4 and
4-MeOC6H4, respectively) did not help to suppress the
exchange of aryl groups. In these cases, only compound 2a was
obtained with incomplete conversion of starting 1d,m; the
exchange went too fast.
In the case of 4-chlorophenyl enynone 1f, carrying out
reaction at 0 °C for 2.5 h resulted in the formation of dienone
3b as a product of mono-hydrophenylation of the acetylene
bond with an incomplete conversion of 1f (Scheme 4). For
this particular reaction, increasing reaction time or tempera-
ture again led to the formation of the aryl group exchange
product 2a.
4-Fluorophenyl substituted enynone 1g gave the product of
exhaustive hydrophenylation E-/Z-2c along with the aryl group
exchange product 2a (Scheme 3). In this case, the electron
Table 3 Reactions of 1a with benzene under the action of different acids at room temperature
Entry
Acid
Equiv. of benzene
Time
Reaction products, yield %
1
2
3
4
5
6
TfOH
TfOH
H2SO4
H2SO4
11
1
11
11
11
Solvent
1 h
1 h
1 h
72 h
12 h
12 h
2a, 98%
Complex mixture
2a, 25% + 2Z-,4E-Ia, 60%
2a, 32% + IIa, 62%
Complex mixture
Complex mixture
AlCl3 (5 equiv.) in CH2Cl2 (solvent)
AlCl3 (5 equiv.) in PhH (solvent)
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presence of electron withdrawing 2-(or 3-)fluorophenyl substi-
tuents in enones 2d and 2e does not allow exchange of these
aryl groups with phenyl ones (no formation of 2a).
Reactions of enynone 1a with other arenes (toluene,
anisole, veratrole, and o-, m-, p-xylenes) in TfOH at room temp-
erature for 1 h led to complex inseparable mixtures of regio-
and stereo-isomers of products of exhaustive hydroarylation of
triple and double bonds in 1a.
Summarizing the data obtained and discussed above, one
may state that solely addition of arenes to the acetylene bond
of enynones 1 proceeds in TfOH for the compounds having
strong electron withdrawing substituents (4-NO2, 2-F, 3-F) in
the aryl ring at the double bond. For other enynones 1, hydro-
arylation occurs at both triple and double carbon–carbon
bonds, and this reaction may be complicated by aryl group
exchange.
Scheme 4 Reaction of enynone 1f with benzene in TfOH at 0 °C
(incomplete conversion of 1f, ∼50%).
Reactions of 3-fluorophenyl (1h, Table 4) and 2-fluorophe-
nyl (1i, Table 5) enynones with benzene in TfOH afforded pro-
ducts of mono-hydrophenylation of the triple bond (3c and 3d
correspondingly) and exhaustive hydrophenylation (2d and 2e
correspondingly). Increasing the reaction time led to the
increase of the yields of 2d and 2e and to the decrease of the
yields of 3c and 3d, respectively (see Tables 4 and 5). This
reveals that enynones 1 give at first mono-hydroarylation
adducts 3, which are further converted into products of double
hydroarylation 2. It should be mentioned that increasing reac-
tion time up to 12–24 h led to the lowering yields of 2d and 2e,
and the formation of oligomeric materials was detected. The
Taking into account the data on the formation of com-
pounds 3a–d and 2a–e (Schemes 3, 4, and Tables 4, 5), one
may conclude that the first hydroarylation step of enynones 1
takes place at the acetylene bond, and then the second hydro-
arylation goes onto the double bond.
A plausible reaction mechanism is presented in Scheme 5.
Protonation of enynones 1 in TfOH gives consequently cations
A, and then vinyl type dications B (see data on DFT calcu-
lations of these species in Table 2). Both species may take part
in electrophilic aromatic substitution with arenes, leading to
cations E, deprotonation of which during aqueous quenching
of the reaction results in dienones 3.
Table 5 Reactions of enynone 1i with benzene in TfOH at room
temperature
Most probably the addition of the second arene molecule to
the double bond of dienones 3 in TfOH leads to the formation
of O,C-diprotonation species F, since the nitro substituted
enynone 1e does not give products of hydroarylation of the
double bond, it forms 3a only (see Scheme 3). For such a de-
activated substrate as 3a, the presence of the acceptor nitro
group should give the corresponding O-protonated (on carbo-
nyl oxygen) species an enhanced electrophilicity (compared to
other substituents), while preventing protonation of the
double bond. Since no reaction proceeds at the double bond,
we assume that protonation is necessary and that species F are
involved. Interaction of cations F with arenes furnishes enones
2 (Scheme 5). Exchange of aryl groups may take place in com-
pounds 2 in the presence of arenes under superacidic reaction
conditions. This exchange may proceed in two ways. First one is
protonation of electron donating aryl ring Ar′ followed by
Reaction
products,
yield %a
Reaction
time
Unreacted recovered
Entry
3d
2e
starting 1i, yield %a
1
2
3
4
5
6
3 min
10 min
45 min
1 h
4 h
9 h
30
72
91
52
28
9
—
—
7
40
74
78
61
26
—
—
—
—
a Yields were determined by NMR.
Table 4 Reactions of enynone 1h with benzene in TfOH at room
temperature
Reaction
products,
yield %a
Reaction
time
Unreacted recovered
Entry
3c
2d
starting 1h, yield %a
1
2
3
4
15 min
45 min
1 h
72
90
84
60
—
2
13
29
20
3
—
—
Scheme 5 A plausible mechanism of hydroarylation of the triple and
6 h
double carbon–carbon bonds in cross-conjugated enynones
1 by
a Yields were determined by NMR.
arenes in Brønsted superacid TfOH.
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Table 7 Reactions of enynones 1 with arenes in the system TfOH–pyri-
dine (4 : 1 vol.) at room temperature for 100 h
elimination of arene molecules with the formation of the corres-
ponding benzyl type cation (alike to species F), which reacts
with arene Ar″H giving the product of aryl group exchange. In
an alternative way, the same benzyl type cation may be formed
at the protonation of the carbon–carbon bond C(H)–C(Ar′) in
the superacid with the leaving of arene molecule Ar′H.
Reaction product, yield
DFT calculations of electronic and thermodynamic charac-
teristics of various protonated forms E1, F1, G1, and H1
derived from dienone 3e are presented in Table 6. Comparison
of dications F1 and G1 shows that F1 has higher electrophili-
city properties, ω value, positive charge and LUMO coefficient
on the reactive center C1, although its formation is less favor-
able from a thermodynamic point of view (see values of ΔG298
of protonation reactions in the scheme in Table 6). So, species
F may act as electrophilic intermediates in reactions of eny-
nones 1 in superacids (see the mechanism in Scheme 5). We
also tried to register NMR spectra of the protonated form of 3e
in TfOH, but obtained a rather complex and ambiguous 1H
NMR spectrum.
Entry Enynone
ArH
%
1
1a Ar′ = Ph
Benzene
2
1a Ar′ = Ph
p-Xylene
3
4
1a Ar′ = Ph
1,2-
Dichlorobenzene
1d Ar′ =
4-MeC6H4
Benzene
To achieve regioselective hydroarylation at the acetylene
bonds of enynones 1, we decided to carry out this reaction in
the system TfOH–pyridine (4 : 1 vol.), which has less acidity
than neat TfOH. We have already used this system to achieve
selective addition of TfOH to acetylene bonds of enynones.8 In
this system, hydroarylation occurred at the acetylene bond
solely, leading to dienones 3, but it needed long time 100 h at
room temperature (Table 7).
5
6
1f Ar′ =
4-ClC6H4
Benzene
Benzene
1h Ar′ =
3-FC6H4
Then, reactions of enynones 1 with arenes were carried out
under the action of acidic zeolite HUSY (CBV-720) in a high
pressure glass tube at high temperature of 85–180 °C for 2–8 h.
It was found that hydroarylation of the triple bond only took
place with the formation of dienones 3 (Table 8). The double
bond of enynones 1 remained unreactive with zeolite CBV-720.
The E-/Z-Configuration of the newly formed double bond
(former acetylenic one) in substances 3 (see Tables 7 and 8)
Additionally, structures of compounds 3b, 3d, 3e, 3l, and 3p
were confirmed by X-ray data (see the ESI†). Hydroarylation of
the triple bond in enynones 1 with zeolite CBV-720 was
efficiently achieved with the following arenes: benzene,
p-xylene, and 1,2-dichlorobenzene. Other arenes, for instance,
o-xylene (entry 3, Table 8), gave a complex mixture of insepar-
able regio- and stereo-isomers. It should be also mentioned
1
was unambiguously determined by H–1H NOESY correlations
that triarylsubstituted dienones
3 are hardly available
compounds. They have been synthesized recently by the
between vinyl and aromatic protons (see the ESI†).
Table 6 Selected electronic characteristics (DFT calculations) of cations E1, F1, G1, and H1 derived from protonation of compound 3e, and calcu-
lated Gibbs energies ΔG298 of protonation reactions
Cation
EHOMO, eV
ELUMO, eV
ωa, eV
q (C1)b, e
q (C3)b, e
q (C5)b, e
k (C1)LUMO c, %
k (C3)LUMO c, %
k (C5)LUMO c, %
E1
F1
G1
H1
−7.17
−8.00
−8.01
−8.51
−3.89
−4.64
−4.54
−4.96
4.7
5.9
5.7
6.4
−0.02
0.21
0.08
0.18
0.50
0.59
0.60
0.80
−0.05
0.23
0.31
0.26
19
17
19
16
17
7
9
12
4
25
10
6
a Global electrophilicity index ω = (EHOMO + ELUMO)2/8(ELUMO − EHOMO). b Natural charges. c Contribution of the atomic orbital to the molecular
orbital.
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Table 8 Reactions of enynones 1 with arenes under the action of acidic zeolite HUSY (CBV-720)
Entry
1
Enynone
Arene, Ar″H
Reaction conditions: temperature, time
85 °C, 2 h
Reaction product, yield %
1a
Benzene
Ar = Ar′ = Ph
2
1a
p-Xylene
140 °C, 2 h
Ar = Ar′ = Ph
3
4
1a
p-Xylene
145 °C, 2 h
100 °C, 2 h
Complex mixture of inseparable
regio- and stereo-isomers, 75%
Ar = Ar′ = Ph
1b
Ar = 4-MeC6H4
Ar′ = Ph
Benzene
4
1c
Benzene
85 °C, 2 h
Ar = 4-MeOC6H4
Ar′ = Ph
5
6
7
1d
Ar = Ph
Ar′ = 4-MeC6H4
Benzene
Benzene
p-Xylene
100 °C, 2 h
85 °C, 2 h
140 °C, 2 h
1f
Ar = Ph
Ar′ = 4-ClC6H4
1f
Ar = Ph
Ar′ = 4-ClC6H4
8
9
1g
Benzene
85 °C, 2 h
Ar = Ph
Ar′ = 4-FC6H4
1g
1,2-Dichlorobenzene
180 °C, 2 h
Ar = Ph
Ar′ = 4-FC6H4
10
11
12
13
1h
Ar = Ph
Ar′ = 3-FC6H4
Benzene
Benzene
Benzene
Benzene
85 °C, 8 h
85 °C, 8 h
85 °C, 2 h
85 °C, 2 h
1i
Ar = Ph
Ar′ = 2-FC6H4
1j
Ar = Ph
Ar′ = 2,4-F2C6H3
1k
Ar = Ph
Hetaryl = 5-bromofuran-2-yl
14
15
1l
Ar = Ph
Hetaryl = thiophen-2-yl
1m
Ar = Ph
Benzene
Benzene
85 °C, 2 h
100 °C, 2 h
Ar′ = 4-MeOC6H4
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Pd-catalyzed reaction of complex arylethynyl cyclopropanoles mation of compounds E-/Z-2f,g correspondingly (Scheme 7). It
with iodoarenes.16
should be noted that compounds 2 are hardly available and
Apart from the main product E-/Z-3m, enynone 1g in reac- they could be promising Michael acceptors in organic
tion with 1,2-dichlorobenzene gave the minor compound 4, synthesis.
which was formed as a result of hydration of the acetylene
bond in 1g by residual water in the reaction system (entry 9,
Table 8). The enolic form of 4 was confirmed by X-ray data
Conclusions
(see the ESI†). The structure of such aryl diketones was
described recently.17
We have developed a method for the regio-selective hydroaryla-
tion of the acetylene bond in cross-conjugated enynones by
arenes in the system TfOH-pyridine or under the action of
HUSY acidic zeolite. A further hydroarylation step of the
double bond in cross-conjugated enynones proceeds in neat
TfOH; however, this reaction may be complicated by exchange
of aryl groups under the superacidic reaction conditions.
One more unusual direction was found in reaction of 1g
and p-xylene with zeolite; in this case, indanone 5 was
obtained (Scheme 6). Most probably the acylation of p-xylene
by 4-fluorocinnamic acid with formation of enone I takes
place. This cinnamic acid along with acetophenone may be
formed in the retro aldol reaction from the corresponding
product of hydration of the acetylene bond of 1g. Protonation
(activation on zeolite acidic sites) of I affords dication G, which
is cyclized into the final product 5 (Scheme 6). The same cycli- Experimental section
zation of 1-phenyl-2-propen-1-ones into indanones using
H-zeolite was found to proceed through intermediate
O,C-diprotonated forms of enones, alike species G.18
Having in hand the procedures for the synthesis of die-
nones 3 (Tables 7 and 8), one may carry out a second hydroary-
lation of the double bond in these compounds by another
arene. It allows conducting one by one addition of two
different arenes to the triple and double bonds of starting eny-
nones 1. To demonstrate this approach, we performed hydro-
phenylation of dienones E-/Z-3f,m that resulted in the for-
The NMR spectra of solutions of compounds in CDCl3 were
recorded on a Bruker AVANCE III 400 (at 400, 376 and
100 MHz for 1H, 19F and 13C NMR spectra respectively) spectro-
meter at 25 °C. The residual proton-solvent peak CDCl3 (δ
7.26 ppm) for 1H NMR spectra and the carbon signal of CDCl3
(δ 77.0 ppm) for 13C NMR spectra were used as references. 19F
NMR spectra were indirectly referenced to the signal of CFCl3
(δ 0.0 ppm). HRMS (ESI-TOF) was carried out on Bruker
maXis-ESI-QTOF Mass Spectrometer instruments. IR spectra of
compounds were recorded with a Bruker spectrometer. The
preparative reactions were monitored by thin-layer chromato-
graphy carried out on silica gel plates (Alugram SIL G/UV-254),
using UV light for detection. Preparative TLC was performed
on silica gel Chemapol L 5/40 with petroleum ether-ethyl
acetate mixture elution.
X-ray diffraction study
A suitable crystal was selected and studied on the diffract-
ometer. The crystal was kept at 100(2) K during data collection.
Using Olex219 the structure was solved with the ShelXS20 struc-
ture solution program using Direct Methods and refined with
the ShelXL refinement package using Least Squares minimiz-
ation. CCDC 1847444 – (3b), 1847451 – (3d), 1847452 – (3e),
1847453 – (3l), 1847454 – (3p), 1847456 – (4).†
Scheme 6 Zeolite promoted reaction of 1g with p-xylene leading to
indanone 5.
DFT calculations
All computations were carried out at the DFT/HF hybrid level
of theory using hybrid exchange functional M06 by using
GAUSSIAN 2009 program packages.21 The geometry optimiz-
ation were performed using the M06/6-311+G(2d,2p) basis set
(standard 6-311 basis set added with polarization (d,p) and
diffuse functions). Optimizations were performed on all
degrees of freedom and solvent-phase optimized structures
were verified as true minima with no imaginary frequencies.
The Hessian matrix was calculated analytically for the opti-
mized structures in order to prove the location of correct
minima and to estimate the thermodynamic parameters.
Scheme 7 Reactions of 3f and m with benzene in TfOH leading to 2f
and g correspondingly.
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Solvent-phase calculations used the Polarizable Continuum (ESI-TOF) m/z [M + Na]+: calcd for C17H10F2ONa 291.0592;
Model (PCM), and the solvent was water.
found 291.0598.
The following enynones were previously obtained and
1-(5-Bromofuran-2-yl)-5-phenylpent-1-en-4-yn-3-one
(1k).
characterized by us:8 1,5-diphenylpent-1-en-4-yn-3-one (1a), Grey crystals. M.p. 122–124 °C. 1H NMR (CDCl3, 400 MHz),
5-(4-methoxyphenyl)-1-phenyl-pent-1-en-4-yn-3-one (1c), 1-(4- δ ppm: 6.48 (d, J = 3.5 Hz, 1H), 6.73 (d, J = 3.5 Hz, 1H), 6.75 (d,
methylphenyl)-5-phenylpent-1-en-4-yn-3-one (1d), 1-(4-nitro- J = 15.9 Hz, 1H), 7.43–7.53 (m, 5H), 7.62 (d, J = 15.9 Hz, 1H).
phenyl)-5-phenylpent-1-en-4-yn-3-one (1e), 1-(4-chlorophenyl)- 13C NMR (CDCl3, 101 MHz), δ ppm: 86.7, 91.4, 114.9, 118.7,
5-phenyl-pent-1-en-4-in-3-one (1f), and 1-(4-methoxyphenyl)-1- 120.2, 126.3, 127.0, 128.7, 130.6, 131.9, 132.9, 152.5, 177.2.
phenylpent-1-en-4-yn-3-one (1m).
HRMS (ESI-TOF) m/z [M + Na]+: calcd for C15H9BrNaO2
5-(4-Methylphenyl)-1-phenylpent-1-en-4-yn-3-one (1b). White 322.9678; found 322.9688.
crystals. M.p. 79–80 °C. 1H NMR (CDCl3, 400 MHz), δ ppm:
5-Phenyl-1-(thiophen-2-yl)pent-1-en-4-yn-3-one (1l).22 Grey
2.41 (c, 3H), 6.90 (d, J = 16.1 Hz, 1H), 7.24–7.32 (m, 2H), crystals. M.p. 79–81 °C. 1H NMR (CDCl3, 400 MHz), δ ppm:
7.44–7.48 (m, 3H), 7.57–7.65 (m, 4H), 7.93 (d, J = 16.3 Hz, 1H). 6.69 (d, J = 15.7 Hz, 1H), 7.12 (t, J = 5.0, 3.7 Hz, 1H), 7.44 (m,
13C NMR (CDCl3, 101 MHz), δ ppm: 21.8, 86.5, 92.2, 117.1, 5H), 7.69–7.61 (m, 2H), 8.00 (d, J = 15.7 Hz, 1H). 13C NMR
128.6, 128.7, 129.1, 129.5, 131.1, 133.0, 134.2, 141.3, 148.0, (CDCl3, 101 MHz), δ ppm: 86.6, 91.2, 120.4, 127.0, 128.6, 129.9,
178.3. HRMS (ESI-TOF) m/z: [M + Na]+ calcd for C18H14ONa: 130.6, 132.4, 132.9, 139.4, 140.2, 177.4. HRMS (ESI-TOF) m/z
269.0937; found 269.0949.
[M + Na]+: calcd for C15H10NaOS 261.0345; found 261.0340.
1-(4-Fluorophenyl)-5-phenylpent-1-en-4-yn-3-one (1g). White
1
crystals. M.p. 85 °C. H NMR (CDCl3, 400 MHz), δ ppm: 6.89
General procedure for reactions of enynones 1 or dienones 3
(d, J = 16.3 Hz, 1H), 6.88–6.99 (m, 2H), 7.40–7.50 (m, 3H),
7.59–7.67 (m, 4H), 8.03 (d, J = 16.3 Hz, 1H). 13C NMR (CDCl3,
101 MHz), δ ppm: 86.6, 91.6, 116.3 (d, J = 22.3 Hz), 120.2,
128.3 (d, J = 2.3 Hz), 128.7, 130.3 (d, J = 3.4 Hz), 130.6 (d, J =
3.6 Hz), 132.9, 146.8, 164.4 (d, J = 252.8 Hz), 177.9. 19F{1H}
NMR (376 MHz, CDCl3), δ ppm: −107.90. HRMS (ESI-TOF) m/z
[M + Na]+: calcd for C17H11FONa 273.0686; found 273.0692.
1-(3-Fluorophenyl)-5-phenylpent-1-en-4-yn-3-one (1h). Yellow
crystals. M.p. 95–96 °C. 1H NMR (CDCl3, 400 MHz), δ, ppm:
6.97 (d, J = 16.3 Hz, 1H), 7.14–7.30 (m, 2H), 7.41–7.54 (m, 4H),
7.61–7.61 (m, 3H), 8.14 (d, J = 16.3 Hz, 1H). 13C NMR (CDCl3,
101 MHz), δ, ppm: 86.6, 92.0, 114.7 (d, J = 21.7 Hz), 117.9 (d,
J = 21.7 Hz), 120.1, 124.6 (d, J = 2.8 Hz), 128.7, 129.6, 130.6 (d,
J = 8.28 Hz), 130.7, 133.0, 136.3 (d, J = 7.71 Hz), 146.5 (d, J =
2.40 Hz), 161.8 (d, J = 247.3 Hz), 177.8. 19F{1H} NMR
(376 MHz, CDCl3), δ, ppm: −114.08. HRMS (ESI-TOF) m/z
[M + Na]+: calcd 273.0686; found 273.0689.
with arenes in TfOH or in the system TfOH–pyridine (4 : 1 vol.)
Enynone 1 (0.08 mmol) was added to a mixture of TfOH
(1 mL) [or TfOH (0.8 mL) and absolute pyridine (0.2 mL)] and
benzene (0.2 mL) or another arene (0.22 mol) and stirred at
room temperature and for the time indicated in Schemes 3, 4,
7 and Tables 4, 5, 7 for each compound 1 or 3. The reaction
mixture was poured into water (10 mL), extracted with CH2Cl2
(4 × 10 mL), washed with a saturated aqueous solution of
NaHCO3 (2 × 10 mL) and water (10 mL), and dried with
Na2SO4. The organic solvent was distilled off under reduced
pressure, if necessary the reaction products were isolated by
preparative thin-layer chromatography (eluent: petroleum
ether–ethyl acetate, 9 : 1 vol.).
General procedure for reactions of enynones 1 with arenes
under the action of acidic zeolite HUSY (CBV-720)
1-(2-Fluorophenyl)-5-phenylpent-1-en-4-yn-3-one (1i). White A mixture of enynone (0.08 mmol), 5 mL of arene and 250 mg
crystals. M.p. 90–91 °C. 1H NMR (CDCl3, 400 MHz), δ ppm: of HUSY zeolite CBV-720 (commercially available material)
6.87 (d, J = 16.1 Hz, 1H), 7.14–7.19 (m, 1H), 7.31–7.33 (m, 1H), pre-calcined at 400–450 °C for 2 h was heated in the high
7.56–7.38 (m, 5H), 7.71–7.62 (m, 2H), 7.88 (d, J = 16.1 Hz, 1H). pressure glass tube at 85–140 °C for 2–8 h (exact temperature
13C NMR (CDCl3, 101 MHz), δ ppm: 86.5, 92.1, 116.4 (d, J = and time for each compound are indicated in Table 8) with vig-
21.9 Hz), 120.1, 124.67 (d, J = 3.6 Hz), 122.3 (d, J = 11.5 Hz), orous stirring. The reaction mixture was then cooled down to
128.7, 128.9 (d, J = 2.33 Hz), 130.4 (d, J = 5.68 Hz), 130.7, 132.7 room temperature. The zeolite was filtered on a glass filter and
(d, J = 8.94 Hz), 133.1, 140.5 (d, J = 3.63 Hz), 161.5 (d, J = washed several times with MeOH (4 × 10 mL). Organic solutions
254.7 Hz), 178.3. 19F{1H} NMR (376 MHz, CDCl3), δ ppm: in benzene and in methanol were combined. The solvents were
−112.07. HRMS (ESI-TOF) m/z [M + Na]+: calcd for C17H11FONa distilled off under reduced pressure, if necessary the reaction
273.0686, found 273.0694.
products were isolated by preparative thin-layer chromatography
1-(2,4-Difluorophenyl)-5-phenylpent-1-en-4-yn-3-one
(1j). (eluent: petroleum ether–ethyl acetate, 9 : 1 vol.).
Yellow crystals. M.p. 95–96 °C. 1H NMR (CDCl3, 400 MHz),
1,1,5,5-Tetraphenylpent-1-en-3-one (2a). Yield 98%. Yellow
1
δ ppm: 6.89 (d, J = 16.3 Hz, 1H), 6.88–6.99 (m, 2H), 7.40–7.50 crystals. M.p. 231 °C. H NMR (400 MHz, CDCl3), δ ppm: 3.01
(m, 3H), 7.59–7.67 (m, 3H), 8.03 (d, J = 16.3 Hz, 1H). 13C NMR (d, 2H, J = 8 Hz), 4.54 (t, 1H, J = 8 Hz), 6.44 (s, 1H), 7.07–7.35
(CDCl3, 101 MHz), δ ppm: 86.4, 92.2, 112.4 (dd, J = 22.0, 3.7 (m, 20 H). 13C NMR (101 MHz, CDCl3), δ ppm: 46.7, 49.2,
Hz), 120.1 (t, J = 25.5 Hz), 128.7, 130.1, 130.2, 130.3, 130.7, 126.4, 127.0, 127.9, 128.5, 128.5, 128.6, 128.8, 129.5, 129.7,
130.8, 133.0, 139.4 (m), 164.5 (d, J = 255.9 Hz), 164.6 (d, J = 139.0, 141.0, 144.0, 153.7, 200.3. IR (KBr) cm−1: 1683 (CvO);
255.3 Hz), 178.1. 19F{1H} NMR (376 MHz, CDCl3), δ ppm: HRMS (ESI-TOF) m/z [M + H]+: calcd for C29H24NaO 411.1725;
−109.46 (d, J = 9.93 Hz), −104.17 (d, J = 9.93 Hz). HRMS found 411.1719.
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1-E-/Z-1-(4-Methylphenyl)-1,5,5-triphenylpent-1-en-3-one (2b).
E-/Z-1-(3,4-Dichlorophenyl)-5-(4-fluorophenyl)-1,5-diphenylpent-
Yield 34%. E-/Z-2b 3 : 1. Yellow oil. E-2b: 1H NMR (400 MHz, 1-en-3-one (2g). Yield 52%. E-/Z-2g 1 : 1. Colorless oil. E-2g:
CDCl3), selected signals δ ppm: 2.35 (s, 3H), 2.98 (d, J = 7.7 Hz, 1H NMR (400 MHz, CDCl3) selected signals δ ppm: 2.95 (dd,
2H), 6.42 (s, 1H). 13C NMR (101 Hz, CDCl3): selected signals δ J = 7.6, 1.7 Hz, 2H), 4.48 (t, J = 7.7 Hz, 1H), 6.35 (c, 1H), 6.77
ppm: 21.3, 46.6, 49.1, 144.0, 153.7, 200.0. Z-2b: 1H NMR (dd, J = 8.2, 2.0 Hz, 1H). 19F{1H} NMR (376 MHz, CDCl3),
(400 MHz, CDCl3) selected signals δ ppm: 2.39 (s, 3H), 3.00 (d, δ ppm: −116.51. 13C NMR (101 Hz, CDCl3): selected signals
J = 7.7 Hz, 2H), 4.52 (t, J = 7.7 Hz, 1H), 6.38 (c, 1H). 13C NMR δ ppm: 43.7, 68.2, 115.4, 122.9, 125.8, 127.7, 128.2, 128.6,
1
(101 Hz CDCl3) selected signals δ ppm: 21.4, 29.7, 44.3, 153.8, 143.2, 157.5, 189.6. Z-2g: H NMR (400 MHz, CDCl3) selected
200.3. E-/Z-2b (for mixture of isomers) 1H NMR δ ppm: signals δ ppm: 3.17 (dd, J = 7.6, 1.7 Hz, 2H), 4.57 (t, J = 7.7 Hz,
7.05–7.24 (m, 21H), 7.27–7.39 (m, 6H). 13C NMR (101 Hz, 1H), 6.55 (c, 1H). 19F{1H} NMR (376 MHz, CDCl3): δ ppm
CDCl3): δ ppm: 126.1, 126.2, 126.3, 126.7, 126.9, 127.8, 127.9, −116.69. E-/Z-2g (for a mixture of isomers) 1H NMR (400 MHz,
128.0, 128.3, 128.4, 128.5, 128.6, 128.7, 129.0, 129.3, 129.4, CDCl3) δ ppm: 6.90–7.07 (m, 17H), 7.32–7.43 (m, 20H). HRMS
129.6, 136.0, 138.1, 138.7, 139.0, 139.1, 139.7, 141.2, 143.9. (ESI-TOF) (for a mixture of isomers) m/z [M + Na]+: calcd for
HRMS (ESI-TOF) (for mixture of isomers) m/z [M + Na]+: calcd C29H21Cl2FO 497.0846; found 497.0861.
for C30H26OCl 425.1876; found 425.1869.
(4E)-5-(4-Nitrophenyl)-1,1-diphenylpenta-1,4-dien-3-one (3a).
1
5-(4-Fluorophenyl)-1,1,5-triphenylpent-1-en-3-one (2c). Yield Yield 98%. Orange crystals. M.p. 129 °C. H NMR (400 MHz,
1
52%. Yellow oil. H NMR (400 MHz, CDCl3) δ, ppm: 3.01 (dd, CDCl3) δ, ppm: 6.42 (d, 1H, J = 15.8 Hz), 6.78 (s, 1H), 7.26–7.33
J = 15.9, 7.6 Hz, 2H), 4.55 (t, J = 7.5 Hz, 1H), 6.47(s, 1H). NMR (m, 4H), 7.39–7.46 (m, 9H), 7.50 (d, 2H, J = 8.8 Hz). 13C NMR
13C (101 MHz, CDCl3): δ ppm: 45.7, 49.1, 115.2 (d, J = 20.9 Hz), (101 MHz, CDCl3) δ, ppm: 123.9, 127.6, 128.4, 128.5, 128.6,
126.3, 126.4, 126.8, 127.78 (d, J = 13.4 Hz), 128.3, 128.4, 128.5, 128.7, 129.4, 129.7, 129.8, 130.4, 137.9, 139.0, 140.6, 141.3,
128.6, 129.6, 139.7 (d, J = 3.1 Hz), 140.9, 153.8, 161.4 (d, J = 148.2, 155.5, 190.6. IR (KBr) cm−1: 1651 (CvO). HRMS
244.4 Hz), 199.8. 19F{1H} NMR (376 MHz, CDCl3), δ ppm: (ESI-TOF) m/z [M + Na]+: calcd for C23H17NaNO3: 378.1106;
−116.36. HRMS (ESI-TOF) m/z [M + H]+: calcd for C29H24OF found 378.1101.
407.1806; found 407.1820. m/z [M + Na]+: calcd for C29H24ONa
(4E)-5-(4-Chlorophenyl)-1,1-diphenylpenta-1,4-dien-3-one (3b).
411.1719, found 411.1736.
Yield 88%. Yellow crystals. M.p. 100–102 °C. The structure was
5-(3-Fluorophenyl)-1,1,5-triphenylpent-1-en-3-one (2d). Yield confirmed by X-ray analysis (see ESI†). 1H NMR (400 MHz,
29%. Obtained in a yellow oil mixture with 3c. 1H NMR CDCl3) δ, ppm: 6.36 (d, J = 15.8 Hz, 1H), 6.77 (s, 1H), 7.14–717
(400 MHz, CDCl3) δ, ppm (selected signals): 2.99 (d, J = 7.6 Hz, (m, 2H), 7.26–7.31 (m, 3H), 7.37–7.43 (m, 10H). 13C NMR
2H), 4.56 (t, J = 7.6 Hz, 1H), 6.46 (s, 1H). 19F{1H} NMR (101 MHz, CDCl3), δ ppm: 126.8, 127.6, 128.4, 128.5, 128.9,
(376 MHz, CDCl3): δ ppm: −113.11.
129.0, 129.2, 129.6, 130.3, 133.5, 135.6, 139.1, 140.1, 140.9,
5-(2-Fluorophenyl)-1,1,5-triphenylpent-1-en-3-one (2e). Yield 154.5, 191.2. HRMS (ESI-TOF) m/z [M + Na]+: calcd for
1
78%. Yellow oil. H NMR (400 MHz, CDCl3), δ ppm: 3.07 (dd, C23H17OClNa 367.0860; found 367.0843.
J = 7.7, 2.05 Hz, 2H), 4.85 (t, J = 7.7 Hz, 1H), 6.51(s, 1H),
(4E)-5-(3-Fluorophenyl)-1,1-diphenylpenta-1,4-dien-3-one (3c).
7.10–7.45 (m, 19H). 13C NMR (101 MHz, CDCl3), δ ppm: 40.0, Yield 91%. Red oil. H NMR (400 MHz, CDCl3): δ, ppm: 6.34
47.9, 115.7 (d, J = 22.6 Hz), 124.1 (d, J = 3.8 Hz), 126.5 (d, J = (d, J = 15.8 Hz, 1H), 6.78 (s, 1H), 6.86 (dr, 9.93, 2.94 Hz, 1H),
12.4 Hz), 127.8, 128.0 (d, J = 8.4 Hz), 128.4, 128.5, 128.7, 128.9 7.22–7.30 (m, 4H), 7.37–7.44 (m, 8H). 13C NMR (101 MHz,
(d, J = 4.6 Hz), 129.4, 129.6, 138.9, 140.9, 142.7, 153.7, 160.6 (d, CDCl3) δ ppm: 114.1 (d, J = 21.9 Hz), 116.9 (d, J = 21.4 Hz),
J = 246.2 Hz), 199.6. 19F {1H} NMR (376 MHz, CDCl3), δ ppm: 124.3 (d, J = 2.9 Hz), 127.4 (d, J = 10.8 Hz), 128.5, 128.7, 129.2,
−116.36. HRMS (ESI-TOF) m/z [M + H]+: calcd for C29H24OF 129.7, 130.2, 130.3, 137.3 (d, J = 7.4 Hz), 139.1, 140.23 (d, J =
1
407.1806; found 407.1833.
2.9 Hz), 140.8, 155.0, 162.9 (d, J = 246.5 Hz), 191.0. 19F{1H}
E-/Z-1-(2,5-Dimethylphenyl)-1,5,5-triphenylpent-1-en-3-one (2f). NMR (376 MHz, CDCl3), δ ppm: −112.84. HRMS (ESI-TOF) m/z
1
Yield 84%. E-/Z-2f 6 : 1. Colorless oil. E-2f: H NMR (400 MHz, [M + Na]+: calcd for C23H17OFNa 351.1156, found 351.1160.
CDCl3) selected signals, δ ppm: 1.94 (s, 3H), 2.30 (s, 3H), 2.90
(4E)-5-(2-Fluorophenyl)-1,1-diphenylpenta-1,4-dien-3-one (3d).
(d, J = 7.4 Hz, 2H), 4.53 (t, J = 7.4 Hz, 1H), 6.62 (s, 1H), 6.82 (s, Yield 55%. Yellow crystals. M.p. 91–95 °C. The structure was
1H). 13C NMR (101 Hz CDCl3) selected signals, δ ppm: 19.1, confirmed by X-ray analysis (see ESI†). 1H NMR (400 MHz,
20.9, 45.9, 49.3, 130.3, 132.7, 135.4, 138.4, 143.8, 153.7, 199.2. CDCl3): δ, ppm: 6.50 (d, J = 16.0 Hz, 1H), 6.77 (s, 1H),
1
Z-2f: H NMR (400 MHz, CDCl3) selected signals, δ ppm: 1.89 6.99–7.06 (m, 2H), 7.26–7.28 (m, 4H), 7.36–7.40 (m, 8H), 7.64
(s, 3H), 3.07 (d, J = 7.4 Hz, 2H), 6.05 (c, 1H). 13C NMR (d, J = 16.0 Hz, 1H). 13C NMR (101 MHz, CDCl3) δ ppm: 116.0
(101 MHz, CDCl3) selected signals δ ppm: 19.8, 47.1, 49.3, (d, J = 22.0 Hz), 123.0 (d, J = 11.7 Hz), 124.2 (d, J = 3.6 Hz),
130.6, 133.0, 135.1, 139.0, 141.5, 144.2, 154.1, 201.3. E-/Z-2f 127.8, 128.7 (d, J = 2.9 Hz), 128.4, 128.7, 129.0, 129.5, 130.1,
1
(for a mixture of isomers) H NMR (400 MHz, CDCl3), δ ppm: 131.4 (d, J = 8.6 Hz), 134.2 (d, J = 2.9 Hz), 139.1, 141.0, 154.3,
7.01–7.24 (m, 16H), 7.28–7.33 (m, 4H). 13C NMR (101 Hz, 161.4 (d, J = 254.0 Hz), 190.7. 19F{1H} NMR (376 MHz, CDCl3),
CDCl3), δ ppm: 126.2, 126.4, 127.0, 127.5, 127.7, 127.9, 128.2, δ ppm: −114.29. HRMS (ESI-TOF) m/z [M + Na]+: calcd for
128.4, 128.5, 128.6, 128.8, 129.0, 129.1, 129.3, 129.4, 129.7. C23H17OFNa 351.1156; found 351.1167.
HRMS (ESI-TOF) (for a mixture of isomers) m/z [M + Na]+:
calcd for C31H28O 439.2032; found 439.2031.
(4E)-1,1,5-Triphenylpenta-1,4-dien-3-one (3e).16 Yield 97%.
Yellow crystals. M.p. 62–65 °C. The structure was confirmed by
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X-ray analysis (see ESI†). H NMR (400 MHz, CDCl3), δ, ppm: NMR (100 MHz, CDCl3), selected signals, δ, ppm: 128.1, 128.5,
6.45 (d, J = 15.9 Hz, 1H), 6.80 (s, 1H), 7.25–7.33 (m, 7H), 128.7, 128.8, 129.9, 141.2. HRMS (ESI-TOF) (for a mixture of
7.39–7.43 (m, 8H), 7.53 (d, J = 15.9 Hz, 1H). 13C NMR isomers) m/z [M + H]+: calcd for C24H20NaO 347.1412; found
(101 MHz, CDCl3), δ ppm: 126.5, 127.6, 128.1, 128.4, 128.5, 347.1412.
128.6, 128.7, 129.0, 129.5, 130.1, 130.2, 134.9, 139.1, 141.1,
141.9, 154.2, 191.5. HRMS (ESI-TOF) m/z [M + Na]+: calcd 3-one (3j). Yield 65%. E-/Z-3j 6 : 1. Yellow oil. 1–3j: 1H NMR
forC23H18NaO 333.1250, found 333.1263. (400 MHz, CDCl3) selected signals δ ppm: 3.84 (s, 1H), 6.83 (d,
(1E/Z),(4E)-1-(4-Methoxyphenyl)-1,5-diphenylpenta-1,4-dien-
(1E/Z),(4E)-1-(2,5-Dimethylphenyl)-1,5-diphenylpenta-1,4-dien- J = 15.85 Hz, 1H), 6.75 (s, 1H), 7.47 (d, J = 15.85 Hz, 1H).
3-one (3f). Yield 82%. E-/Z-3f 5 : 1. Yellow oil. E-3f: 1H NMR 13C NMR (100 MHz, CDCl3) selected signals, δ, ppm: 113.9,
1
(400 MHz, CDCl3), selected signals δ, ppm: 2.07 (s, 3H), 2.30 120.3, 154.5, 183.7. 2–3j: H NMR (400 MHz, CDCl3), selected
(s, 3H), 6.44 (d, J = 15.8 Hz, 1H), 6.91 (s, 1H), 6.97 (s, 1H), 7.48 signals, δ, ppm: 3.79 (s, 1H), 6.73 (d, J = 15.9 Hz, 1H), 6.67 (s,
(d, J = 15.8 Hz, 1H). 13C NMR (101 Hz CDCl3): selected signals, 1H). 7.50 (d, J = 15.9 Hz, 1H). 13C NMR (100 MHz, CDCl3),
δ, ppm: 19.4, 20.9, 125.9, 127.7, 128.1, 128.6, 141.7, 153.9, selected signals, δ, ppm: 113.8, 119.8, 153.7, 182.3. E-/Z-3j (for
190.7. Z-3f: 1H NMR (400 MHz, CDCl3), selected signals, a mixture of isomers) 1H NMR (400 MHz, CDCl3), δ ppm:
δ ppm: 2.06 (s, 3H), 2.36 (s, 3H), 6.40 (c, 1H), 6.49 (d, J = 16.0 7.42–7.46 (m 18H). 13C NMR (100 MHz, CDCl3) δ, ppm: 125.9,
Hz, 1H), 7.54 (d, J = 16.0 Hz, 1H). 13C NMR (101 Hz CDCl3): 126.4, 126.6, 126.7, 128.1, 128.4, 128.5, 128.7, 128.8, 128.9,
selected signals, δ ppm: 20.0, 126.8, 142.0, 154.5, 192.4. E-/Z-3f 129.9, 130.1, 130.2, 130.5, 130.6, 131.3, 131.4, 131.9, 132.0,
1
(for a mixture of isomers) H NMR (400 MHz, CDCl3), δ ppm: 132.1, 133.5, 134.7, 137.8, 141.3. HRMS (ESI-TOF) (for a
7.09–7.39 (m, 15H). 13C NMR (101 Hz CDCl3): δ ppm: 128.2, mixture of isomers) m/z [M + H]+: calcd for C24H20O2 341.1536;
128.7, 128.8, 128.9, 129.1, 129.3, 129.5, 129.6, 129.8, 130.0, found 341.1549, m/z [M + Na]+: calcd for C24H19O2Na 363.1356;
130.1, 130.3, 130.5, 130.7, 133.0, 135.0, 138.4, 140.0. HRMS found 363.1371, m/z [M + K]+: C24H19O2K 379.1095; found
(ESI-TOF) (for a mixture of isomers) m/z [M + Na]+: calcd for 379.1126.
C25H22ONa 361.1563; found 361.1580.
(1E/Z),(4E)-5-(4-Chlorophenyl)-1-(2,5-dimethylphenyl)-1-phenyl-
(1E/Z),(4E)-1-(3,4-Dichlorophenyl)-1,5-diphenylpenta-1,4-dien- penta-1,4-dien-3-one (3k). Yield 88%. E-/Z-3k 4 : 1. Yellow oil.
1
3-one (3g). Yield 75%. E-/Z-3g 1.25 : 1. Colorless oil. E-3g: 1H E-3k: H NMR (400 MHz, CDCl3) selected signals, δ ppm: 2.07
NMR (400 MHz, CDCl3) selected signals, δ ppm: 6.43 (d, 1H, (s, 3H), 2.30 (s, 3H), 6.44 (d, J = 15.8 Hz, 1H), 6.91 (s, 1H), 6.97
J = 16.0 Hz), 6.74 (s, 1H), 7.22 (dd, 1H, J = 8.0 Hz, 2.0 Hz), (s, 1H), 7.48 (d, J = 15.8 Hz, 1H). 13C NMR (101 Hz CDCl3)
7.26–7.47 (m, 12H), 7.52 (d, 1H, J = 16.0 Hz). 13C NMR selected signals, δ ppm: 19.3, 20.9, 126.3, 127.7, 128.3, 128.7,
(100 MHz, CDCl3) selected signals, δ, ppm: 126.1, 126.9, 127.7, 128.9, 129.2, 154.3, 190.5. Z-3k: 1H NMR (400 MHz, CDCl3),
128.2, 128.2, 128.5, 128.7, 128.8, 129.4, 130.0, 130.4, 131.5, selected signals, δ ppm: 2.06 (s, 3H), 2.36 (s, 3H), 6.40 (s, 1H),
132.8, 134.6, 138.0, 140.2, 142.5, 151.3, 191.0. Z-3g: 1H NMR 6.49 (d, J = 16.0 Hz, 1H), 7.54 (d, J = 16.0 Hz, 1H). 13C NMR
(400 MHz, CDCl3), selected signals, δ, ppm: 6.43 (d, 1H, J = 16 (101 Hz CDCl3) selected signals, δ ppm: 19.2, 21.0, 155.0,
Hz), 6.88 (s, 1H), 7.14 (dd, 1H, J = 8.0 Hz, 2.0 Hz), 7.26–7.47 192.1. E-/Z-3k (for a mixture of isomers) 1H NMR (400 MHz,
(m, 12H), 7.59 (d, 1H, J = 16.0 Hz). 13C NMR (100 MHz, CDCl3), CDCl3), δ ppm: 7.09–7.39 (m, 15H). 13C NMR (101 Hz CDCl3) δ
selected signals, δ, ppm: 126.1, 126.9, 128.3, 128.4, 128.7, ppm: 127.1, 127.3, 127.7, 127.9, 129.0, 129.3, 129.4, 129.6,
128.7, 128.9, 129.2, 129.9, 130.3, 130.5, 132.6, 133.6, 134.7, 129.7, 129.8, 130.4, 130.7, 131.1, 133.1, 133.4, 133.6, 135.3,
139.1, 141.1, 143.2, 151.8, 190.1. HRMS (ESI-TOF) (for a 135.6, 135.7, 135.8, 135.9, 138.4, 139.9, 140.0, 140.2 HRMS
mixture of isomers) m/z [M + Na]+: calcd for C23H16Cl2ONa (ESI-TOF) (for a mixture of isomers) m/z [M + H]+: calcd for
401.0470; found 401.0470.
C25H21OClNa 395.1173; found 395.1158.
(4E)-5-(4-Methylphenyl)-1,1-diphenylpenta-1,4-dien-3-one (3h).
Yield 98%. Yellow oil. H NMR (400 MHz, CDCl3), δ ppm: 2.34 Yield 91%. Brown crystals. M.p. 85–87 °C. The structure was
(s, 3H), 6.39 (d, J = 15.9 Hz, 1H), 6.76 (s, 1H), 7.09–7.16 (m, confirmed by X-ray analysis (see the ESI†). H NMR (400 MHz,
(4E)-5-(4-Fluorophenyl)-1,1-diphenylpenta-1,4-dien-3-one (3l).
1
1
4H), 7.26–7.29 (m, 2H), 7.37–7.39 (m, 8H), 7.48 (d, J = 15.9 Hz, CDCl3), δ ppm: 6.29 (d, J = 15.8 Hz, 1H), 6.75 (s, 1H), 6.95 (t,
1H). 13C NMR (101 MHz, CDCl3), δ ppm: 21.4, 125.6, 128.1, J = 8.6 Hz, 2H), 7.18–7.22 (m, 2H), 7.26–7.29 (m, 2H), 7.36 (m,
128.4, 128.4, 128.6, 129.5, 130.2, 139.1, 140.5, 141.1, 142.0, 8H), 7.42–7.46 (d, J = 15.8 Hz, 1H). 19F {1H} NMR (376 MHz,
153.9, 191.6. HRMS (ESI-TOF) m/z [M + Na]+: calcd for CDCl3): δ ppm: −109.81. 13C NMR (101 MHz, CDCl3), δ ppm:
C24H20ONa 347.1406; found 347.1422.
115.3 (d, J = 62.3 Hz), 126.2, 127.6, 128.4, 128.48, 128.65,
(1E/Z),(4E)-1-(4-Methylphenyl)-1,5-diphenylpenta-1,4-dien-3- 129.526, 129.9 (d, J = 8.4 Hz), 130.2, 131.2 (d, J = 3.1 Hz), 138.9,
one (3i). Yield 98%. E-/Z-3i 10 : 1. Orange crystals. E-3i: 1H 140.4, 141.0, 154.3, 162.5 (d, J = 252 Hz), 191.3. HRMS
NMR (400 MHz, CDCl3) selected signals, δ ppm: 2.41 (s, 3H), (ESI-TOF) m/z [M + Na]+: calcd for C23H17OFNa 351.1156;
6.44 (d, 1H, J = 15.8 Hz), 6.79 (s, 1H), 7.09–7.24 (m, 5H), found 351.1163.
7.36–7.40 (m, 9H), 7.52 (d, 1H, J = 15.8 Hz). 13C NMR
(1E/Z),(4E)-1-(3,4-Dichlorophenyl)-5-(4-fluorophenyl)-1-phenyl-
(100 MHz, CDCl3) selected signals, δ ppm: 21.3, 126.5, 126.8, penta-1,4-dien-3-one (3m). Yield 19%. E-/Z-3m 1 : 1. Yellow oil.
128.1, 128.4, 128.7, 129.2, 130.2, 135.0, 138.2, 139.8, 141.5, E-3m: 1H NMR (400 MHz, CDCl3), selected signals, δ ppm:
154.5, 191.3. Z-3i: 1H NMR (400 MHz, CDCl3), selected signals, 6.30 (d, J = 15.8 Hz, 1H), 6.70 (s, 1H), 7.11 (dd, J = 8.2, 2.1 Hz,
δ, ppm: 2.40 (s, 3H), 6.43 (d, 1H, J = 15.8 Hz), 6.76 (s, 1H). 13C 1H). 13C NMR (101 Hz CDCl3) selected signals, δ ppm: 141.0,
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161.0 (d, J = 241.5 Hz), 189.9. 19F {1H} NMR (376 MHz, CDCl3), 2H), 16.15 (c, 1H). 13C NMR (CDCl3, 101 MHz), δ ppm: 29.7,
δ ppm: −109.02. Z-3m: 1H NMR (400 MHz, CDCl3), selected 97.6, 116.1 (d, J = 22.2 Hz), 123.1 (d, J = 2.0 Hz), 127.4, 128.7,
signals, δ ppm: 6.54 (d, J = 15.9 Hz, 1H), 6.84 (s, 1H), 7.51 (d, 129.8 (d, J = 8.1 Hz), 132.6, 136.2, 138.7, 159.3 (d, J = 254.5 Hz),
J = 15.9 Hz, 1H). 13C NMR (101 Hz CDCl3), selected signals, 179.3, 189.3. 19F {1H} NMR (376 MHz, CDCl3), δ ppm: −109.96.
δ ppm: 141.84, 160.1 (d, J = 241.5 Hz), 190.8. 19F {1H} NMR HRMS (ESI-TOF) m/z [M + Na]+: calcd for C17H13FO2Na
(376 MHz, CDCl3), δ ppm: −109.41. E-/Z-3m: (for a mixture of 291.0792, found 273.0789.
isomers) 1H NMR (400 MHz, CDCl3), δ ppm: 6.96–7.08 (m,
3-(4-Fluorophenyl)-4,7-dimethylindan-1-one (5). Yield 35%.
5H), 7.18–7.23 (m, 5H), 7.32–7.45 (m, 14 H). 13C NMR (101 Hz Yellow oil. 1H NMR (400 MHz, CDCl3), δ ppm: 1.96 (s, 3H),
CDCl3), δ ppm: 115.8, 116.0, 122.4, 126.9, 127.9, 129.4, 129.7, 2.52 (dd, J = 19.0, 2.59 Hz, 1H), 2.67 (s, 3H), 3.19 (dd, J = 19.0,
129.9, 130.1, 130.3, 130.5, 131.5. HRMS (ESI-TOF) (for a 8.49 Hz, 3H), 4.51 (dd, J = 8.4, 2.32 Hz, 1H), 6.92–7.00 (m, 4H),
mixture of isomers) m/z [M + Na]+: calcd for C23H15Cl2FONa 7.10 (d, J = 7.5 Hz, 1H), 7.23 (d, J = 7.6 Hz, 1H). 13C NMR
419.0376; found 419.0356.
(101 MHz, CDCl3), δ ppm: 18.05, 18.1, 42.5, 48.0, 115.7, 128.8
(4E)-5-(2,4-Difluorophenyl)-1,1-diphenylpenta-1,4-dien-3-one (d, J = 8.1 Hz), 130.3, 133.6, 134.4, 135.9 (d, J = 8.7 Hz), 139.9
(3n). Yield 69%. Orange crystals. M.p. 58–59 °C. 1H NMR (d, J = 2.9 Hz) 155.9, 161.6 (d, J = 245.1 Hz), 207.2. 19F {1H}
(400 MHz, CDCl3), δ ppm: 6.41 (d, J = 16.0 Hz, 1H), 6.75 (s, NMR (376 MHz, CDCl3), δ ppm: −116.36. HRMS (ESI-TOF) m/z
1H), 6.88–6.68 (m, 2H), 7.19–7.04 (m, 1H), 7.31–7.21 (m, 2H), [M + H]+: calcd for C17H15FO 255.1180; found 255.1188.
7.37 (m, 8H), 7.56 (d, J = 16.0 Hz, 1H). 13C NMR (101 MHz,
CDCl3): δ ppm: 104.1 (t, J = 25.7 Hz), 111.7 (dd, J = 18.7, 3.7
Hz), 119.9 (dd, J = 10.9, 4.2 Hz), 127.3, 128.4, 128.5, 128.7,
129.0, 129.6, 129.7 (dd, J = 12.02, 4.5 Hz), 130.2, 133.0, 140.0,
Conflicts of interest
140.9, 154.7, 160.3 (dd, J = 210, 9.9 Hz), 162.9 (dd, J = 210, There are no conflicts to declare.
9.9 Hz). 19F {1H} NMR (376 MHz, CDCl3), δ ppm: −106.34 (d,
J = 9.2 Hz), −109.81 (d, J = 9.2 Hz). HRMS (ESI-TOF) m/z
[M + Na]+: calcd for C23H16F2ONa 369.1061; found 369.1057.
(4E)-5-(5-Bromofuran-2-yl)-1,1-diphenylpenta-1,4-dien-3-one
Acknowledgements
(3o). Yield 71%. Brown oil. 1H NMR (400 MHz, CDCl3), δ ppm: This work was supported by the Russian Scientific Foundation
6.34 (d, J = 15.5 Hz, 2H), 6.34 (d, J = 3.4 Hz, 1H), 6.43 (d, J = 3.4 (grant no. 18-13-00008). Spectral studies were performed at the
Hz, 1H), 6.73 (s, 1H), 6.73 (s, 1H), 7.13 (d, J = 15.5 Hz, 1H), Center for Magnetic Resonance, Center for Chemical Analysis
7.28–7.21 (m, 2H), 7.37 (m, 8H). 13C NMR (101 MHz, CDCl3), and Materials Research and Research Center for X-ray
δ ppm: 114.2, 116.8, 124.7, 125.2, 126.8, 127.8, 128.3, 128.4, Diffraction Studies of Saint Petersburg State University, Saint
128.6, 129.0, 129.6, 130.0, 138.9, 141.0, 153.4, 154.6, 190.3. Petersburg, Russia.
HRMS (ESI-TOF) m/z [M + Na]+: calcd for C21H15BrO2Na
401.0148; found 401.0152.
(4E)-1,1-Diphenyl-5-(thiophen-2-yl)penta-1,4-dien-3-one (3p).
Yield 81%. Brownish crystals. The structure was confirmed by
References
X-ray analysis (see ESI†). 1H NMR (400 MHz, CDCl3), δ ppm:
6.20 (d, J = 15.5 Hz, 1H), 6.73 (s, 1H), 6.97 (dd, J = 5.0, 3.6 Hz,
1H), 7.11 (d, J = 3.6 Hz, 1H), 7.26 (m, 3H), 7.36–7.41 (m, 8H),
7.60 (d, J = 15.5 Hz, 1H). 13C NMR (101 MHz, CDCl3), δ ppm:
125.4, 127.5, 128.1, 128.4, 128.5, 128.6, 129.1, 129.5, 130.1,
131.1, 134.2, 139.0, 140.5, 141.1, 154.3, 190.7. HRMS (ESI-TOF)
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3.83 (s, 3H), 6.36 (d, 1H, J = 15.6 Hz), 6.78 (s, 1H), 7.20–7.31
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δ ppm: 6.34 (s, 1H), 6.58 (d, J = 15.8 Hz, 1H), 7.08–7.16 (m,
4H), 7.47–7.64 (m, 3H), 7.66 (d, J = 15.8 Hz, 1H), 7.94–7.97 (m,
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