Reactions of N-phenylamide and phenyl (thio)esters of 3-phenylpropiolic acid with benzene under superelectrophilic activation

Article abstract of DOI:10.1007/s11172-012-0117-3

N-Phenylamide and phenyl (thio)esters of 3-phenylpropiolic acid add benzene in the presence of CF₃SO₃H or AlX₃ (X = Cl, Br) to give 4,4-diphenyl-3,4-dihydroquinolin-2-one, 4,4-diphenyl-3,4- dihydrocoumarin, and 4,4-dipheny

Full text of DOI:10.1007/s11172-012-0117-3

Russian Chemical Bulletin, International Edition, Vol. 61, No. 4, pp. 843—846, April, 2012
843
Reactions of Nꢀphenylamide and phenyl (thio)esters of
3ꢀphenylpropiolic acid with benzene under superelectrophilic activation
D. S. Ryabukhin,a A. V. Vasilyev,a,b and S. Yu. Vyazminb
aSaint Petersburg State Forest Technical University,
5 Institutskii per., 194021 Saint Petersburg, Russian Federation.
Fax: +7 (812) 670 9390. Eꢀmail: aleksvasil@mail.ru
bDepartment of Chemistry, Saint Petersburg State University,
26 Universitetsky prosp., 198504 Saint Petersburg, Russian Federation.
Fax: +7 (812) 428 6733
NꢀPhenylamide and phenyl (thio)esters of 3ꢀphenylpropiolic acid add benzene in the
presence of CF3SO3H or AlX3 (X = Cl, Br) to give 4,4ꢀdiphenylꢀ3,4ꢀdihydroquinolinꢀ2ꢀone,
4,4ꢀdiphenylꢀ3,4ꢀdihydrocoumarin, and 4,4ꢀdiphenylꢀ3,4ꢀdihydrothiocoumarin, respectively.
Key words: 3ꢀphenylpropiolic acid, carbocations, superelectrophilic activation, quinolines,
coumarins, thiocoumarins.
Quinoline and coumarin derivatives are of great pracꢀ
tical importance. They are generally applied in chemistry,
biology, medicine, and nanotechnology.1—4 Such heteroꢀ
cyclic systems are the key fragments of many natural and
synthetic biologically active compounds, they exhibit
phosphorescent properties and are used in organic lightꢀ
emitting diodes (OLEDs).4 Thiocoumarins are poorly
studied class of organic compounds, which may possess
valuable practical properties. Development of novel synꢀ
thetic procedures towards derivatives of quinoline, coumarin,
and thiocoumarin is a topical task of organic chemistry.
Superelectrophilic activation is one of the promising
strategies in organic synthesis. It involves generation of
reactive species with two or more cationic centers either
by protonation of the basic centers of organic compounds
in the Brønsted superacids of low nucleophilicity or by
coordination of aforementioned centers to strong Lewis
acids.5 In the alkyne chemistry, superelectrophilic activaꢀ
tion opens access to various unsaturated compounds, carꢀ
boꢀ and heterocycles.6
Earlier, we used superelectrophilic activation by the
Brønsted superacids (CF3SO3H, HSO3F) or strong Lewis
acids (AlCl3, AlBr3) for the intramolecular cyclization of
Nꢀarylamides, phenyl esters and thioesters of 3ꢀarylꢀ
propiolic acids into 4ꢀarylquinolinꢀ2ꢀones,7 4ꢀphenylꢀ
coumarins,8 and 4ꢀphenylthiocoumarins,9 respectively.
The aim of the present work is studying the reactions of
Nꢀphenylamide and phenyl (thio)esters of 3ꢀphenylꢀ
propiolic acid with benzene under superelectrophilic acꢀ
tivation.
of the carbonyl group C=O and the carbon atom of the
triple CC bond or coordination of these basic centers to
strong Lewis acids produced superelectrophilic dications
2a—c (Scheme 1). The latter can further be transformed
by several competing routes. The first route is intramolecꢀ
ular cyclization to give compounds 3a—c (see Refs 7—9)
arising from interaction of vinyl cationic center with the
internal  nucleophile, namely, the phenyl ring of the XPh
(X = NH, O, S) moiety (route A). The second route is
intermolecular addition of the superacid CF3SO3H moleꢀ
cules or a chloride ion to yield vinyl triflates7 or vinyl
chlorides9 4a—c (route B). In the presence of benzene
(external  nucleophile), the third competing reaction inꢀ
volving akenylation of benzene to afford compounds 5a—c
is possible (route C). The latter under the reaction condiꢀ
tions can undergo intramolecular cyclization into comꢀ
pounds 6a—c. These results are summarized in Table 1.
Compound 1a in CF3SO3H gave reaction products folꢀ
lowing all three routes, viz., 4ꢀphenylquinolinꢀ2ꢀone (3a),
4,4ꢀdiphenylꢀ3,4ꢀdihydroquinolinꢀ2ꢀone (6a), and vinyl
triflate (4a) in a low yield of 10% (see Table 1, entry 1).
The ratio of products 3a and 6a reflects the contribution of
the different pathways of the reaction of dication 2a with
 nucleophiles, namely, intramolecular reaction with the
PhNH fragment (see Scheme 1, route A) and intermolecꢀ
ular reaction with benzene (route C). Similar yields of
compounds 3a (48%) and 6a (40%) indicate that probaꢀ
bility of transformation of dication 2a via these routes is
approximately equal.
Electrophilic activation of compound 1a by AlCl3 faꢀ
vored the intermolecular route C. Thus, the yield of diꢀ
hydroquinolinone 6a (91%) is higher than the yield of
Either protonation of 3ꢀphenylpropiolic acid derivaꢀ
tives 1a—c in the Brønsted superacids at the oxygen atom
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 0840—0843, April, 2012.
1066ꢀ5285/12/6104ꢀ0843 © 2012 Springer Science+Business Media, Inc.

844
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 4, April, 2012
Ryabukhin et al.
Scheme 1
1—6: X = NH (a), O (b), S (c); Y = TfO (4a), Cl (4b,c)
Table 1. Transformations of 3ꢀphenylpropiolic acid derivatives on treatment with CF3SO3H or AlX3 (X = Cl,
Br) in the presence of benzene (see Scheme 1)
Entry
Starting
Reaction conditions
Products (Yield (%))
compound
1
2
3
4
5
6
7
8
1a
1a
1a
1b
1b
1b
1b
1c
1c
1c
1c
1c
CF3SO3H, C6H6, 20 C, 75 h
AlCl3, C6H6, 80 C, 1 h
AlBr3, C6H6, 80 C, 1 h
CF3SO3H, C6H6, 20 C, 0.5 h
AlCl3, C6H6, 20 C, 2 h
AlBr3, C6H6, 20 C, 2 h
AlBr3, C6H6, 20 C, 10 h
CF3SO3H, C6H6, 20 C, 1 h
AlCl3, C6H6, 20 C, 2 h
AlBr3, C6H6, 20 C, 2 h
AlBr3, C6H6, 20 C, 8 h
AlBr3, C6H6, 80 C, 1 h
3a (48), 6a (40), 4a (10)
3a (8), 6a (91)
3a (65), 6a (34)
6b (13), 3,3ꢀdiphenylindanꢀ1ꢀone (7) (63)
4b (28), 6b (13), 7 (52)
3b (59), 6b (8), 7 (24)
3b (64), 6b (25), 7 (7)
3c (90), 7 (8)
3c (44), Eꢀ4c (19), Zꢀ4c (12), 6c (26)
3c (60), 6c (37)
3c (70), 6c (28)
9
10
11
12
3c (55), 6c (37), 7 (7)
quinolinone 3a (8%) (see Table 1, entry 2). On the conꢀ
trary, the use of AlBr3 for superelectrophilic activation
facilitated intramolecular cyclization of dication 2a into
quinolinone 3a (65%), while the yield of compound 6a
was 34% (see Table 1, entry 3).
Reaction of ester 1b with benzene in CF3SO3H furꢀ
nished 4,4ꢀdiphenylꢀ3,4ꢀdihydrocoumarin (6b) (13%) and
3,3ꢀdiphenylindanꢀ1ꢀone (7) (63%) (see Table 1, entry 4).
The latter is a result of addition of two benzene molecules
to the triple bond of compound 1b followed by intraꢀ
molecular acylation as it have been described earlier.8
When AlCl3 was used (see Table 1, entry 5), vinyl chloride
4b is additionally formed (see Scheme 1, route B). On
going to AlBr3, the major product is 4ꢀphenylcoumarin 3b
(see Table 1, entries 6 and 7) (route A is favored). The highest
yield of dihydrocoumarin 6b (25%) was achieved with
AlBr3—C6H6 mixture at 20 C for 10 h (see Table 1, entry 7).
In the reaction under consideration, thioester 1c gave
rise to a set of products 3c, 4c, and 6c (see Table 1, entries
8—12), which are structurally related to the compounds
obtained from phenyl ester 1b. Superelectrophilic activaꢀ
tion of compound 1c by CF3SO3H, AlCl3, and AlBr3
favored the formation of 4ꢀphenylthiocoumarin (yields
44—90%) (see Scheme 1, route A). Catalysis with AlBr3
provided the highest yield of dihydrothiocoumarin 6c
(37%) (entries 10—12).
Formation of competing reaction products 3a—c and
6a—c in different electrophilic systems (CF3SO3H or AlX3

Superelectrophilic activation of propiolates
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 4, April, 2012
845
Scheme 2
X = NH (a), O (b), S (c)
synthesized according to the known procedure10 by the reactions
of 3ꢀphenylpropiolic acid with aniline, phenol, and thiophenol,
respectively. N,3,3ꢀTriphenylacrylamide (5a), phenyl 3,3ꢀdiꢀ
phenylpropenoate (5b), and Sꢀphenyl 3,3ꢀdiphenylpropꢀ2ꢀ
enethioate (5c) by the known procedure10 by the reactions of
3,3ꢀdiphenylpropenic acid with aniline, phenol, and thiophenol,
respectively.
N,3,3ꢀTriphenylacrylamide (5a). Yield 27%, m.p. 130—132 C
(cf. Ref. 11: m.p. 129—130 C). 1H NMR (CDCl3), : 6.50 (s, 1 H,
=CH—); 6.84 (br.s, 1 H, H arom.); 7.01 (t, 1 H, H arom.,
J = 7.5 Hz); 7.08 (d, 2 H, H arom., J = 8.2 Hz); 7.20 (d, 2 H,
H arom., J = 7.5 Hz); 7.31—7.36 (m, 7 H, H arom.); 7.47—7.48
(m, 2 H, H arom.); 7.47 (s, 1 H, NH) (cf. Ref. 11).
Phenyl 3,3ꢀdiphenylpropenoate (5b). Yield 76%, m.p.
120—122 C (cf. Ref. 12: m.p. 122—123 C). 1H NMR (CDCl3),
: 6.57 (s, 1 H, =CH—); 6.98 (d, 2 H, H arom., J = 7.8 Hz); 7.15
(t, 1 H, H arom., J = 7.8 Hz); 7.27—7.31 (m, 4 H, H arom.);
7.35—7.39 (m, 8 H, H arom.) (cf. Ref. 13). GCꢀMS, m/z
(Irel (%)): 300 [M]+ (10), 207 (100), 178 (45), 152 (8), 105 (9).
SꢀPhenyl 3,3ꢀdiphenylpropꢀ2ꢀenethioate (5c). Yield 86%,
m.p. 145—146 C. 1H NMR (CDCl3), : 6.66 (s, 1 H, =CH—);
7.23—7.24 (m, 2 H, H arom.); 7.31—7.39 (m, 13 H, H arom.).
GCꢀMS, m/z (Irel (%)): 315 [M]+ (10), 207 (100), 178 (45), 152
(8), 105 (9). Found (%): C, 79.67; H, 5.14. C21H16OS. Calculatꢀ
ed (%): C, 79.71; H, 5.10.
Transformations of compounds 1a—c and 5a—c on treatment
with CF3SO3H in the presence of benzene (general procedure). To
a mixture of CF3SO3H (2 mL) and benzene (1 mL), compound
1a—c or 5a—c (1.0 mmol) was added, the mixture was stirred at
20 C for 0.5—75 h (see Table 1, entries 1, 4, 8), poured into
water (50 ml), and extracted with CHCl3 (3×50 mL). The comꢀ
bined organics were washed with water, saturated aqueous
NaHCO3, again with water, and dried with Na2SO4. The solꢀ
vent was removed in vacuo, the product was purified by column
chromatography (silica gel, elution with petroleum ether—ethyl
acetate).
(X = Cl, Br)) is the result of different activation degree of
compounds 1a—c (amount of positive charge on species
2a—c) in these systems and nucleophilicity of the reaction
media as well. The results obtained (see Table 1) indicate
that in the vast majority of cases, activation of acetylene
derivatives 1a—c by the Lewis acids AlX3 (X = Cl, Br)
provided dehydro derivatives 6a—c in higher yields as comꢀ
pared with activation by the Brønsted superacids CF3SO3H
(cf. yields of 6a in entries 1 and 2; yields of 6b in entries 4
and 7; and yields of 6c in entries 8—12).
Formation of compounds 6a—c precisely via route C
(see Scheme 1) was confirmed by cyclization of the preꢀ
liminary synthesized derivatives of 3,3ꢀdiphenylacrylic acid
5a—c on treatment with CF3SO3H or AlCl3—CH2Cl2
(Scheme 2). Intermediate formation of dications 8a—c
was assumed. A possible alternative pathway towards diꢀ
hydro derivatives 6a—c starting from compounds 3a—c
was not confirmed. Thus, no formation of compounds
6a—c was observed upon keeping compounds 3a—c in
CF3SO3H—C6H6 or AlCl3—C6H6 mixtures, the starting
3a—c were recovered quantitatively.
In summary, under superelectrophilic activation by the
Brønsted superacid CF3SO3H or strong Lewis acids AlX3
(X = Cl, Br), derivatives of 3ꢀphenylpropiolic acid 1a—c
react with benzene to give products of the competing reacꢀ
tions, viz., compounds 3a—c, 5a—c or 6a—c, the product
ratios in every specific case is determined by both the strucꢀ
ture of the staring compound 1a—c and the type of acid
used for the activation (CF3SO3H or AlX3).
Experimental
1
H and 13C NMR spectra were run on a Bruker AMꢀ500 (at
Transformations of compounds 1a—c and 5a—c on treatment
with aluminum halides in the presence of benzene (general proceꢀ
dure). To a mixture of AlBr3 or AlCl3 (5.0 mmol) in benzene
(10 mL), compound 1a—c or 5a—c (1.0 mmol) was added, the
mixture was stirred at 20—80 C for 1—10 h (see Table 1, entries
2, 3, 5—7, and 9—12). The products were isolated as described
above.
Physicochemical parameters of 4ꢀphenylquinolinꢀ2ꢀone
(3a)7, 4ꢀphenylcoumarin (3b)8, 4ꢀphenylthiocoumarin (3c)9,
(Z)ꢀ3ꢀoxoꢀ1ꢀphenylꢀ3ꢀ(phenylamino)propꢀ1ꢀenyl trifluoroꢀ
methanesulfonate (4a)8, Sꢀphenyl (E/Z)ꢀ3ꢀchloroꢀ3ꢀphenylꢀ
working frequencies of 500 and 125 MHz, respectively) in
CDCl3. IR spectra (neat) were obtained on a FSMꢀ1201 instruꢀ
ment. Mass spectra (EI) were recorded on a MXꢀ1321 instruꢀ
ment. Gas chromatography/mass spectrometry (GC/MS) was
performed on a G 2570A GC/MSD (Agilent Technologies
6850c) instrument, capillary column HPꢀ5MS (3 m × 0.25 mm),
thickness of the stationary phase was 0.25 m, helium was used
as a carrier gas.
N,3ꢀDiphenylpropiolamide (1a),7 phenyl 3ꢀphenylpropiolꢀ
ate (1b),8 and Sꢀphenyl 3ꢀphenylpropꢀ2ꢀynethioate (1c)9 were

846
Russ.Chem.Bull., Int.Ed., Vol. 61, No. 4, April, 2012
Ryabukhin et al.
propꢀ2ꢀenethioate (4c),9 and 3,3ꢀdiphenylindanꢀ1ꢀone (7)14
were published earlier.
Methods of the Synthesis and Modification of Heterocycles.
Volume 6. Quinolines: Chemistry and Biological Activity], Ed.
V. G. Kartsev, MBFNP (ICFSPF), Moscow, 2007, 744
(in Russian).
2. R. P. Korivi, C. H. Cheng, J. Org. Chem., 2006, 71, 7079.
3. B. M. Trost, F. D. Toste, K. Greenman, J. Am. Chem. Soc.,
2003, 125, 4518.
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5. G. A. Olah, D. A. Klumpp, Superelectrophiles and their Chemꢀ
istry, Wiley, New York, 2008.
Phenyl 3ꢀchloroꢀ3ꢀphenylpropꢀ2ꢀeneoate (4b) (exact Eꢀ or
Zꢀconfiguration was not established) was synthesized in the mixꢀ
1
ture with compound 3b, oil. H NMR (signals of compound 4b
in the mixture), : 5.99 (s, 1 H, =CH—); 7.16—7.92 (m, 10 H,
H arom.). GCꢀMS, m/z (Irel (%)) : 258 [M]+ (8), 222 (5), 194 (7),
165 (100), 137 (10), 102 (25).
4,4ꢀDiphenylꢀ3,4ꢀdihyroquinolinꢀ2ꢀone (6a). M.p. 250—252 C.
IR, /cm–1: 3300 (N—H), 1682 (C=O). 1H NMR, : 3.40 (s, 2 H,
CH2); 6.77, 6.84 (both d, 1 H each, HAr, J = 8.4 Hz); 6.99
(t, 1 H, HAr, J = 7.4 Hz); 7.05 (d, 4 H, HAr, J = 7.4 Hz); 7.23
(t, 2 H, HAr, J = 8.4 Hz); 7.28—7.35 (m, 5 H, HAr); 7.68 (s, 1 H,
NH). 13C NMR, : 44.46, 51.79, 116.14, 123.02, 127.03, 128.18,
128.33, 128.57, 129.41, 131.27, 136.92, 143.59, 173.11. MS (EI,
70 eV), m/z (Irel (%)): 299 [M]+ (69), 256 (24), 222 (100), 204
(28), 106 (28). Found (%): C, 84.30; H, 5.68; N, 4.65. C21H17NO.
Calculated (%): C, 84.25; H, 5.72; N, 4.68.
6. A. V. Vasilyev, Zh. Org. Khim., 2009, 45, 9 [Russ. J. Org.
Chem. (Engl. Transl.), 2009, 45, 1].
7. D. S. Ryabukhin, A. V. Vasilyev, Zh. Org. Khim., 2008, 44,
1875 [Russ. J. Org. Chem. (Engl. Transl.), 2008, 44, 1849].
8. D. S. Ryabukhin, G. K. Fukin, A. V. Cherkasov, A. V. Vasiꢀ
lyev, Zh. Org. Khim., 2009, 45, 1260 [Russ. J. Org. Chem.
(Engl. Transl.), 2009, 45, 1252].
4,4ꢀDiphenylꢀ3,4ꢀdihydrocoumarin (6b). M.p. 150—151 C
(cf. Ref. 15: m.p. 150—151 C). 1H NMR, : 3.56 (s, 2 H, CH2);
7.12—7.51 (m, 14 H, HAr). GCꢀMS, m/z (Irel (%)): 300 [M]+
(70), 272 (10), 257 (100), 223 (24), 181 (35), 165 (20), 152 (15).
9. D. S. Ryabukhin, A. V. Vasilyev, E. V. Grinenko, Zh. Org.
Khim., 2011, 47, 612 [Russ. J. Org. Chem. (Engl. Transl.),
2011, 47, 619].
10. B. Neises, W. Steglich, Angew. Chem., Int. Ed. Engl., 1978,
17, 522.
1
4,4ꢀDiphenylꢀ3,4ꢀdihydrothiocoumarin (6c). Oil. H NMR,
: 3.68 (s, 2 H, CH2); 6.78 (d, 1 H, HAr, J = 7.8 Hz); 6.97 (d, 4 H,
HAr, J = 5.5 Hz); 7.15 (td, 1 H, H arom., J = 2.2 Hz, J = 7.8 Hz);
7.27—7.30 (m, 8 H, H arom.). GCꢀMS, m/z (Irel (%)): 316 [M]+
(60), 288 (30), 273 (70), 239 (15), 211 (45), 197 (100), 178 (25),
165 (23). Found (%): C, 79.76; H, 5.04. C21H16OS. Calculatꢀ
ed (%): C, 79.71; H, 5.10.
11. K. Inamoto, T. Saito, K. Hiroya, T. Doi, J. Org. Chem.,
2010, 75, 3900.
12. D. B. Denney, R. L. Ellsworth, D. Z. Denney, J. Am. Chem.
Soc., 1964, 86, 1116.
13. M. Natarajan, V. T. Ramakrishnan, Ind. J. Chem., Sect. B,
1984, 23, 720.
14. A. O. Shchukin, A. V. Vasilyev, E. V. Grinenko, Zh. Org.
Khim., 2010, 46, 81 [Russ. J. Org. Chem. (Engl. Transl.), 2010,
46, 82].
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 12ꢀ03ꢀ00311ꢀa).
15. W. H. Starnes, Jr., J. Am. Chem. Soc., 1964, 86, 5603.
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