Functionalized 2'-carboxamidodeoxybenzoins by ring opening of 3-aryl-1H-isochromen-1-ones with secondary amines

Article abstract of DOI:10.1007/s10593-016-1874-y

[Figure not available: see fulltext.] An efficient approach based on pyrone ring opening in 3-arylisocoumarins in the presence of cyclic secondary amines was developed in order to prepare amides of deoxybenzoin-2'-carboxylic acids, diverse functionalized

Full text of DOI:10.1007/s10593-016-1874-y

DOI 10.1007/s10593-016-1874-y
Chemistry of Heterocyclic Compounds 2016, 52(4), 275–278
LETTERS TO THE EDITOR
Functionalized 2'-carboxamidodeoxybenzoins by ring opening
of 3-aryl-1H-isochromen-1-ones with secondary amines
1
1
1
Olga V. Shablykina , Viktoria S. Moskvina *, Valentina V. Ishchenko ,
1
1
Eugenia B. Valter , Volodymir P. Khilya
1
Taras Shevchenko National University of Kyiv,
1
2 L. Tolstoy St., Kyiv 01033, Ukraine
e-mail: v.moskvina@gmail.com
Published in Khimiya Geterotsiklicheskikh Soedinenii,
016, 52(4), 275–278
Submitted February 3, 2016
Accepted after revision April 11, 2016
2
An efficient approach based on pyrone ring opening in 3-arylisocoumarins in the presence of cyclic secondary amines was developed in
order to prepare amides of deoxybenzoin-2'-carboxylic acids, diverse functionalized structures useful for the synthesis of polyfunctional
compounds.
Keywords: 3-arylisocoumarins, 2'-carboxamidodeoxybenzoins, N-nucleophiles, amidation, ring opening.
The interest in deoxybenzoin chemistry1–3 is driven by
the useful reactivity of their methylene and carbonyl
fragments, that may be further expanded by adding other
functional groups. For example, the presence of a carboxyl
group at position 2' of the deoxybenzoin system modifies
the typical chemical properties by increasing the activity of
the methylene group. Unfortunately, the synthetic use of
temperature not less than 80°С (Scheme 1). The cyclic
secondary amine morpholine is one of the best options for
the preparation of the open deoxybenzoin form from
isocoumarin due to its stronger nucleophilic activity in
comparison to acyclic analogs and the sufficiently high
boiling point that allows to reach temperatures optimal for
this reaction without the use of elevated pressure; the use of
piperidine and pyrrolidine is also effective in this regard.
2
'-carboxyl deoxybenzoins is significantly complicated by
4 5,6
their susceptibility to acid- or base-catalyzed cyclization
into 3-aryl-1H-isochromen-1-ones (3-arylisocoumarins). This
process can be prevented by transforming the 2'-carboxyl
group into an amide group, particularly by the interaction
of 3-arylisocoumarins with secondary amines. Although
such transformation is characteristic for the 1H-isochromen-
Scheme 1
O
O
3
6
'
'
NH
X
O
4'
N
5
'
X

, 4–5 h
1
-one system, ring opening of 3-arylisocoumarins caused
R
66–95%
2
by the action of secondary amines has been studied very
3
1
a–g
O
7
R
little; mainly the hetero analogs of isocoumarins, such as
pyranopyrimidinones and pyranopyridinediones,
8
9,10
6
4
and
5
also condensed systems (the products in that case are not
deoxybenzoins and do not contain methylene or carbonyl
groups)1 have been investigated.
2a–g, 3a,e, 4a
a R = 4-OH, b R = 4-OH-3-Me, c R = 2-OH-5-Me,
1,12
d R = 2,4-(OH) , e R = 4-OMe, f R = 4-OMe-3-Me,
2
g R = 2,4-(OMe) ; 2 X = O, 3 X = CH , 4 X = none
2
2
In this article, we propose a simple and convenient
method for the transformation of 3-arylisocoumarins 1 with
methoxy and hydroxy groups in their phenyl substituent
into the respective 2'-carboxamidodeoxybenzoins 2–4,
specifically, by heating the appropriate isocoumarin with
a fivefold excess of secondary amine for 4–5 h at
The proposed method has the particular advantages of
high yields and the ease of final product extraction. In most
cases, it suffices upon the completion of the reaction
to treat the reaction mixture with cold alcohol to obtain
0
009-3122/16/52(4)-0275©2016 Springer Science+Business Media New York
275

Chemistry of Heterocyclic Compounds 2016, 52(4), 275–278
a crystalline and spectrally pure compound, and only
dard. For the mass spectrometry, an Agilent 1100 LC/MSD
mass spectrometer was operated using atmospheric
pressure chemical ionization (APCI) source in the positive
ion mode. Mass spectrometry conditions were as follows:
drying gas (nitrogen) temperature 350°C, drying gas flow
7.0 l/min, nebulizer pressure 60 psig, vaporizer temperature
325°C, capillary voltage 4000 V. Melting points were
determined using a Kofler-type Leica Galen III micro hot
stage microscope. The reaction progress and identity of the
obtained compounds were controlled by TLC on
compounds with multiple hydroxy groups (e.g., containing
a resorcinol residue) may require precipitating the product
with dilute acid followed by recrystallization.
We observed that the methylene group of the deoxy-
1
benzoins 2a–g, 3a,e gave two wide H NMR signals at
4
.50 ppm due to the impeded rotation of this group; and
only in the case of the smaller pyrrolidinyl amide residue in
compound 4a the signal of the respective methylene group
was a two-proton singlet.
It should be noted that the open-chain derivatives of
isocoumarins, 2'-carboxydeoxybenzoins 5, can also be used
for the synthesis of 2'-carboxamidodeoxybenzoins 2–4
Merck F254 plates using a CHCl
eluent.
3
–MeOH, 19:1, system as
The initial 3-arylisocoumarins 1a–d with a hydroxy
group were synthesized according to literature;14 their
methoxy derivatives 1е–g were prepared via Williamson
ether synthesis: solution of compound 1a–d (0.01 mol),
(
Scheme 2), but that is not advisable due to the much
higher reactivity of isocoumarin compared to the cor-
responding acid (similarly to vinyl ester).
dimethyl sulfate (1.04 ml g, 0.011 mol) and K
2
CO
3
(4.15 g,
Scheme 2
0.03 mol) in Me CO (50 ml) was stirred and refluxed for
2
2
h; then cooled and poured into H O (100 ml) and HCl
2
N
was added dropwise to pH 5–6; the precipitate was filtered
H
1
OH
off and crystallized from methanol. H NMR spectra
correspond to literature data.6
OH
O
X
1
2–4
Reaction of 3-arylisocoumarins 1 with secondary
amines (General method). A solution of 3-aryl-1H-iso-
chromen-1-one (0.02 mol) and the appropriate cyclic
secondary amine (morpholine, piperidine, or pyrrolidine)
O
Ar
5
(
0.10 mol) was stirred and heated up to 80°C for 4–5 h
TLC control). The reaction mixture was then diluted
(
1
The analysis of H NMR spectra of the reaction mixture
taken after refluxing the acid 5e (Ar = 4-MeOC ) in
equiv of morpholine for 5 h established that the con-
5-fold with cold i-PrOH (in the case of compound 2d the
reaction mixture was poured into 150 ml of H O and 10%
6
H
4
2
5
HCl was added in small portions to pH 4–5). The
precipitate was filtered off and crystallized from 70%
aqueous ethanol.
version rate was 70%, while the cyclic compound 1e was
fully transformed under the same conditions. Therefore, the
use of acids 5 for the synthesis of deoxybenzoins 2 requires
a prolonged reaction time (up to 8 h) and a larger quantity
of an amine (up to 7 equiv), which adversely affects the
product yield and purity.
1-(4-Hydroxyphenyl)-2-[2-(4-morpholinylcarbonyl)-
phenyl]ethanone (2a). Yield 6.19 g (95%), white powder,
–1
mp 221–222°C. IR spectrum, ν, cm : 1567, 1577, 1609,
1
1677. H NMR spectrum, δ, ppm (J, Hz): 3.18 (2H, br. s,
Another technique for the synthesis of deoxybenzoin
from 3-phenylisocoumarins via heating a parent compound
H morpholine); 3.25–3.65 (6H, br. m, H morpholine); 4.10–
4.60 (2H, br. s, СН ); 6.89 (2H, d, J = 8.6, Н-3,5); 7.25
2
7
in aqueous dimethylamine solution has been described, but
(1H, d, J = 7.6, Н-6'); 7.28–7.40 (3Н, m, Н-3',4',5'); 7.91
13
turned out to be inefficient for obtaining compounds 2–4
due to the low conversion rates of isocoumarins 1; and
refluxing in an alcohol solution with 1–2 equiv of an amine
that was proposed for the opening of thioisocoumarin ring
system13 was unsuccessful as well.
(2H, d, J = 8.6, Н-2,6); 10.40 (1H, br. s, 4-ОH). C NMR
spectrum, δ, ppm: 42.0; 42.2; 47.9 (2C); 66.6 (2C); 116.0;
126.7; 127.1; 128.8; 129.4 (2C); 131.4; 132.4; 134.1;
136.8; 162.9; 169.2; 195.9. Mass spectrum, m/z (Irel, %):
+
326 [M+H] (100). Found, %: С 70.01; Н 5.68; N 4.26.
Thus, treating 3-arylcoumarins containing electron-
donating moieties (hydroxy and methoxy groups) in the
C
19
H
19NO . Calculated, %: C 70.14; H 5.89; N 4.31.
4
1-(4-Hydroxy-3-methylphenyl)-2-[2-(4-morpholinyl-
3
-aryl ring with an excess of a sufficiently nucleophilic
carbonyl)phenyl]ethanone (2b). Yield 5.68 g (84%),
–1
secondary amine (morpholine is recommended) produces
white powder, mp 147–148°C. IR spectrum, ν, cm : 1595,
1
2
'-carboxamidodeoxybenzoins in high yields and is a
1603, 1677. H NMR spectrum, δ, ppm (J, Hz): 2.12 (3H,
convenient method for the synthesis of such compounds.
s, 3-CH
J = 13.8, СН
3
); 3.34–3.75 (8Н, m, H morpholine); 4.02 (1Н, d,
2
); 4.62 (1Н, d, J = 13.8, СН ); 6.55 (1Н, d,
2
Experimental
J = 8.0, Н-5); 7.13–7.19 (2Н, m, Н-3',6'); 7.26 (1Н, t,
J = 7.8, Н-4'); 7.31 (1Н, t, J = 7.8, Н-5'); 7.42 (1Н, d,
J = 8.0, Н-6); 7.70 (1Н, s, Н-2); 8.50 (1Н, br. s, 4-ОН).
IR spectra of samples in KBr pellets were recorded on
1
a Perkin Elmer Spectrum BX II spectrometer. H and
1
3
13
C NMR spectra were acquired on a Mercury-400 spectro-
C NMR spectrum, δ, ppm: 16.2; 42.6; 48.5 (2C); 66.9;
meter (400 and 100 MHz, respectively) in DMSO-d
:1 (compounds 2a, 3a, 4a) and CDCl (others compounds)
solutions. The TMS signal was used as an internal stan-
6
–CCl
4
,
114.7; 125.4; 126.5; 127.0; 128.7; 129.9 (2C); 131.6;
131.7; 132.3; 133.7; 135.5; 160.4; 170.9; 196.1. Mass
spectrum, m/z (Irel, %): 340 [M+H] (100). Found, %: С 70.64;
1
3
+
2
76

Chemistry of Heterocyclic Compounds 2016, 52(4), 275–278
Found, %: С 71.29; Н 6.47; N 3.91. C21
Н 6.16; N 4.03. C20
H
4
21NO . Calculated, %: С 70.78;
H
23NO . Calcu-
4
H 6.24; N 4.13.
lated, %: C 71.37; H 6.56; N 3.96.
1
-(2-Hydroxy-5-methylphenyl)-2-[2-(4-morpholinyl-
1-(2,4-Dimethoxyphenyl)-2-[2-(4-morpholinylcarbonyl)-
carbonyl)phenyl]ethanone (2с). Yield 4.75 g (70%),
phenyl]ethanone (2g). Yield 6.20 g (84%), biege powder,
–
1
–1
biege powder, mp 141–142°C. IR spectrum, ν, cm : 1601,
mp 163–164°C. IR spectrum, ν, cm : 1600, 1623, 1658.
1
1
1
634, 1642. H NMR spectrum, δ, ppm (J, Hz): 2.35 (3H,
s, 5-CH ); 3.37–3.73 (8Н, m, H morpholine); 4.29 (1H,
br. s, СН ); 4.82 (1H, br. s, СН ); 6.92 (1H, d, J = 7.8,
Н-3); 7.25–7.45 (5Н, m, Н-4,3',4',5',6'); 7.71 (1H, s, Н-6);
H NMR spectrum, δ, ppm (J, Hz): 3.29 (2H, br. s,
3
H morpholine), 3.44–3.70 (6H, m, H morpholine); 3.77
2
2
(3H, s, 4-ОCH
J = 16.0, СН
3
); 3.83 (3H, s, 2-ОCH
3
); 4.19 (1Н, d,
); 6.45 (1Н, s,
2
); 4.56 (1Н, d, J = 16.0, СН
2
1
3
1
4
1
1
1.90 (1H, s, 2-ОН). C NMR spectrum, δ, ppm: 20.8;
2.1; 42.4; 48.1 (2C); 66.9; 118.5; 126.6; 127.3; 128.7;
29.7 (2C); 130.1; 132.1; 132.3; 136.2; 139.2; 160.6;
Н-3); 6.45 (1Н, d, J = 8.6, Н-5); 7.09–7.16 (2Н, m,
Н-3',6'); 7.19 (1Н, t, J = 7.4, Н-4'); 7.25 (1Н, t, J = 7.4,
13
Н-5'); 7.73 (1H, d, J = 8.6, Н-6). C NMR spectrum,
δ, ppm: 42.1; 47.9; 48.1; 55.8 (2C); 67.1 (2C); 98.7; 105.6;
120.8; 126.3; 126.7; 129.3; 132.0; 133.0; 134.1; 136.5;
161.4; 165.0; 170.4; 197.0. Mass spectrum, m/z (Irel, %): 370
+
69.9; 203.8. Mass spectrum, m/z (Irel, %): 340 [M+H]
(
100). Found, %: С 70.63; Н 6.15; N 4.05. C20
H
21NO .
4
Calculated, %: С 70.78; H 6.24; N 4.13.
+
1
-(2,4-Dihydroxyphenyl)-2-[2-(4-morpholinylcarbonyl)-
[M+H] (100). Found, %: С 68.20; Н 6.21; N 3.73.
phenyl]ethanone (2d). Yield 4.51 g (66%), white powder,
C
21
H
23NO . Calculated, %: С 68.28; H 6.28; N 3.79.
5
–
1
mp 181–182°C. IR spectrum, ν, cm : 1577, 1613, 1630.
1-(4-Hydroxyphenyl)-2-[2-(1-piperidinylcarbonyl)-
1
H NMR spectrum, δ, ppm (J, Hz): 3.33 (2H, br. s,
phenyl]ethanone (3a). Yield 4.77 g (74%), white powder,
–1
H morpholine); 3.45–3.70 (6H, m, H morpholine); 4.05
mp 226–227°C. IR spectrum, ν, cm : 1564, 1580, 1603,
1
(
(
1Н, d, J = 16.0, СН
2
); 4.58 (1Н, d, J = 16.0, СН
2
); 6.16
1679. H NMR spectrum, δ, ppm (J, Hz): 1.40–1.60 (6H,
1Н, dd, J = 8.8, J = 2.2, Н-5); 6.25 (1Н, d, J = 2.2, Н-3);
.14–7.21 (2Н, m, Н-3',6'); 7.26 (1Н, t, J = 7.6, Н-4'); 7.33
m, H piperidine); 3.05–3.25 (2H, m, H piperidine); 3.49–
7
3.51 (2H, m, H piperidine); 4.18 (1Н, d, J = 10.2, СН );
2
(
1Н, t, J = 7.6, Н-5'); 7.41 (1H, d, J = 8.8, Н-6); 9.08 (1H,
4.41 (1Н, d, J = 10.2, СН ); 6.88 (2H, d, J = 8.0, Н-3,5);
2
1
3
br. s, 4-ОН); 12.38 (1H, s, 2-ОН). C NMR spectrum,
δ, ppm: 42.1; 42.6; 48.5; 66.8 (2C); 103.8; 108.5; 113.0;
7.19 (1H, d, J = 7.2, Н-6'); 7.26–7.38 (3Н, m, Н-3',4',5');
7.88 (2H, d, J = 8.0, Н-2,6); 10.47 (1H, br. s, 4-ОH).
13
1
1
26.71; 127.3; 130.2; 132.4; 132.6; 132.8; 135.2; 164.9;
C NMR spectrum, δ, ppm: 24.2; 25.4 (2C); 25.8; 41.6;
65.6; 170.9; 201.1. Mass spectrum, m/z (Irel, %): 342
41.7; 47.8 (2C); 115.5; 125.9; 126.6; 128.4; 128.7; 130.9;
+
[
M+H] (100). Found, %: С 66.72; Н 5.53; N 4.03.
131.8; 133.2; 137.2; 162.4; 168.5; 195.4. Mass spectrum, m/z
+
C
19
1
H
19NO
5
. Calculated, %: С 66.85; H 5.61; N 4.10.
(Irel, %): 324 [M+H] (100). Found, %: С 74.21; Н 6.48;
-(4-Methoxyphenyl)-2-[2-(4-morpholinylcarbonyl)-
N 4.28. C20
H21NO . Calculated, %: С 74.28; H 6.55; N 4.33.
3
phenyl]ethanone (2e). Yield 4.82 g (71%), white powder,
1-(4-Methoxyphenyl)-2-[2-(1-piperidinylcarbonyl)-
–
1
mp 110–111°C. IR spectrum, ν, cm : 1599, 1625, 1676.
phenyl]ethanone (3e). Yield 5.05 g (74%), white
1
–1
H NMR spectrum, δ, ppm (J, Hz): 3.34–3.37 (2Н, m,
powder, mp 94–95°C. IR spectrum, ν, cm : 1602, 1619,
1
H morpholine); 3.45 (1Н, br. s, H morpholine); 3.59 (3Н,
br. s, H morpholine); 3.70–3.81 (2Н, m, H morpholine);
1679. H NMR spectrum, δ, ppm (J, Hz): 1.10–1.40 (6H,
m, H piperidine); 2.86 (1H, br. s, H piperidine); 2.99 (1H,
br. s, H piperidine); 3.17 (1H, br. s, H piperidine); 3.48
3
.91 (3Н, s, ОСН
3
); 4.15 (1Н, d, J = 15.2, СН
); 6.99 (2Н, d, J = 8.6, Н-3,5); 7.24 (1Н, d,
2
); 4.76 (1Н,
d, J = 15.2, СН
2
(1H, br. s, H piperidine); 3.61 (3H, s, ОСН
J = 16.0, СН ); 4.32 (1Н, d, J = 16.0, СН
3
); 3.89 (1Н, d,
); 6.68 (2H, d,
J = 7.8, Н-6'); 7.27–7.35 (2Н, m, Н-3',4'); 7.40 (1Н, t, J = 7.8,
2
2
1
3
Н-5'); 8.04 (2Н, d, J = 8.6, Н-2,6). C NMR spectrum, δ,
J = 8.8, Н-3,5); 6.95 (1H, d, J = 7.2, Н-6'); 6.98–7.10 (3Н,
13
ppm: 42.1; 42.4; 48.1 (2C); 55.8; 66.9; 114.1 (2C); 126.4;
m, Н-3',4',5'); 7.77 (2H, d, J = 8.8, Н-2,6). C NMR
spectrum, δ, ppm: 23.9; 25.0; 25.6; 41.5; 41.8; 47.8 (2C);
54.9; 113.2 (2C); 125.3; 126.1; 128.3; 129.1; 130.8 (2C);
131.9; 136.3; 163.0; 169.0; 195.4. Mass spectrum, m/z (Irel, %):
1
1
27.0; 129.5; 129.9; 130.9 (2C); 132.1; 133.4; 136.2;
64.0; 170.1; 196.1. Mass spectrum, m/z (Irel, %): 340
+
[
M+H] (100). Found, %: С 70.69; Н 6.15; N 4.02.
+
C
20
1
H
21NO
4
. Calculated, %: С 70.78; H 6.24; N 4.13.
-(4-Methoxy-3-methylphenyl)-2-[2-(4-morpholinyl-
carbonyl)phenyl]ethanone (2f). Yield 5.92 g (84%), biege
338 [M+H] (100). Found, %: С 74.68; Н 6.82; N 4.11.
C
21
H
23NO . Calculated, %: С 74.75; H 6.87; N 4.15.
3
1-(4-Hydroxyphenyl)-2-[2-(1-pyrrolidinylcarbonyl)-
–
1
powder, mp 117–118°C. IR spectrum, ν, cm : 1578, 1601,
phenyl]ethanone (4a). Yield 4.14 g (67%), white powder,
1
–1
1
618, 1670. H NMR spectrum, δ, ppm (J, Hz): 2.10 (3H,
s, 3-CH ); 3.15–3.18 (2H, m, H morpholine); 3.25–3.70
6H, m, H morpholine); 3.73 (3H, s, 4-ОCH ); 3.97 (1Н, d,
J = 16.0, СН ); 4.55 (1Н, d, J = 16.0, СН ); 6.71 (1Н, d,
mp 232–233°C. IR spectrum, ν, cm : 1563, 1582, 1609,
1
3
1678. H NMR spectrum, δ, ppm (J, Hz): 1.65–1.70 (4H,
(
3
m, H pyrrolidine); 3.15 (2H, t, J = 4.3, H pyrrolidine); 3.26
2
2
(2H, t, J = 4.3, H pyrrolidine); 4.36 (2Н, s, СН ); 6.88 (2H,
2
J = 8.8, Н-5); 7.04 (1Н, d, J = 7.2, Н-3'); 7.10 (1Н, d,
J = 7.2, Н-6'); 7.13 (1Н, t, J = 7.2, Н-4'); 7.20 (1Н, t,
J = 7.2, Н-5'); 7.67 (1Н, br. s, Н-2); 7.74 (1Н, dd, J = 8.8,
J = 1.4, Н-6). C NMR spectrum, δ, ppm: 16.5; 42.1; 42.4;
8.1 (2C); 55.8; 66.9 (2C); 109.6; 126.3; 126.9; 127.2;
28.8; 129.5; 131.1; 132.0; 133.5; 136.3; 162.2; 170.1;
d, J = 8.8, Н-3,5); 7.22–7.35 (4Н, m, Н-3',4',5',6'); 7.88
13
(2H, d, J = 8.8, Н-2,6). C NMR spectrum, δ, ppm: 24.2;
25.8; 41.7; 45.3; 48.6; 115.5 (2C); 126.2; 126.7; 128.3;
128.8; 130.9 (2C); 131.7; 133.1; 138.3; 162.6; 168.7; 195.6.
13
+
4
1
1
Mass spectrum, m/z (Irel, %): 310 [M+H] (100). Found, %:
С 73.71; Н 6.12; N 4.47. C19
H
19NO . Calculated, %: С 73.77;
3
+
96.3. Mass spectrum, m/z (Irel, %): 354 [M+H] (100).
H 6.19; N 4.53.
2
77

Chemistry of Heterocyclic Compounds 2016, 52(4), 275–278
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