Studies on quinazoline chemistry. 5. Synthesis of 3,4-dihydroquinazolines with functional substituents at C-2 atom and their alkylation reactions

Article abstract of DOI:10.1007/s10593-013-1163-y

Syntheses are reported for a new series of 2-substituted 4,4-diphenyl-3,4-dihydroquinazolines by the reaction of o- aminophenyldiphenylcarbinol (APC) with various nitriles. The reaction of APC with substituted 5-bromo-3-cyano-2(1H)-pyridones leads to the formation of derivatives of two products: 3,4-dihydroquinazolines and 4H-3,1-benzoxazines. The alkylation of 3,4-dihydroquinazolines using dimethyl sulfate proceeds through N,N-dimethylation. The structure of these products is a function of the nature of the substituent at C-2 atom of the heterocycle.

Full text of DOI:10.1007/s10593-013-1163-y

Chemistry of Heterocyclic Compounds, Vol. 48, No. 10, January, 2013 (Russian Original Vol. 48, No. 10, October, 2012)
STUDIES ON QUINAZOLINE CHEMISTRY. 5.* SYNTHESIS OF
3,4-DIHYDROQUINAZOLINES WITH FUNCTIONAL SUBSTITUENTS
AT C-2 ATOM AND THEIR ALKYLATION REACTIONS
E. V. Gromachevskaya1**, E. A. Kaigorodova2, K. S. Pushkareva3, and G. D. Krapivin1
Syntheses are reported for a new series of 2-substituted 4,4-diphenyl-3,4-dihydroquinazolines by the
reaction of o-aminophenyldiphenylcarbinol (APC) with various nitriles. The reaction of APC with
substituted 5-bromo-3-cyano-2(1H)-pyridones leads to the formation of derivatives of two products:
3,4-dihydroquinazolines and 4H-3,1-benzoxazines. The alkylation of 3,4-dihydroquinazolines using
dimethyl sulfate proceeds through N,N-dimethylation. The structure of these products is a function of
the nature of the substituent at C-2 atom of the heterocycle.
Keywords: dimethyl sulfate, 4,4-diphenyl-3,4-dihydroquinazolines, alkylation, mass-spectral
fragmentation.
In previous works [2, 3], we reported that o-aminophenyldiphenylcarbinol (APC, 1) reacts with nitriles
to give 2,4,4-trisubstituted 3,4- or 1,4-dihydroquinazolines, which exist in solution as tautomeric 1H- and
3H-forms. Furthermore, quinazolines with an active methylene group directly bound to the quinazoline system
can exist in solution as four tautomeric forms A-D with migration of the double bond to an exocyclic position
[2].
Ph
Ph
Ph
Ph
Ph
Ph
ArCH2CN
NH
OH
NH
Ar
Ar
N
NH2
N
H
А
1
B
Ph
Ph
N
Ph
Ph
NH
Ar
N
N
H
H
D
Ar
C
_______
*For Communication 4, see [1].
**To whom correspondence should be addressed, e-mail: organics@kubstu.ru.
1Kuban State Technological University, 2 Moskovskaya St., Krasnodar 350072, Russia.
2Kuban State Agrarian University, 13 Kalinina St., Krasnodar 350044, Russia; e-mail: e_kaigorodova@mail.ru.
3Kuban State University, 149 Stavropol'skaya St., Krasnodar 350028, Russia; e-mail: bukov@chem.kubsu.ru.
________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1603-1613, October, 2012.
Original article submitted December 14, 2011.
0009-3122/13/4810-1492©2013 Springer Science+Business Media New York
1492

Esters of cyanoacetic acid react with APC 1 to give alkyl 2-(4,4-diphenyl-3,4-dihydroquinazolin-2(1H)-
yl-idene)acetates 2a,b as two geometric isomers (B and C) stabilized by intramolecular hydrogen bonding [2].
Ph
Ph
O
Ph
Ph
NH
NC
NH
O
OR
1
N
H
N
OR
H
O
OR
B
C
2a,b
a R = Me, b R = Et
Our study of the chemical properties of such compounds has shown an unusual course for the alkylation
and acylation reactions [1-3]. Thus, the methylation using dimethyl sulfate, which is a soft electrophile,
proceeds as N- and C-dimethylation with migration of the double bond within the heterocyclic system [2].
Acylation with carboxylic acid halides, which are hard electrophiles, proceeds not at the nitrogen atoms, but
rather as C-acylation at the α-position to the heterocycle, leading to an equilibrium mixture of π-diastereomers
3.
Ph
Ph
Ph
Ph
Ph
Ph
R1COHal
COOR
NH
NH
NH
COR1
COOR
N
N
N
H
H
COR1
H
COOR
3
R = Alk, R1 = Alk, Ar
In a continuation of our study of the reactions of APC 1 with nitriles in acidic medium [2, 3], we
investigated the reaction of this compound with an expanded range of nitriles 4a-j, containing various functional
groups and also the alkylation of the products obtained.
Carbinol 1 in the presence of HClO4 transforms into the stable triaryl carbenium cation [2], which reacts
with nitriles 4a-i forming 3,4-dihydroquinazolinium perchlorates 5a-i through a 1,4-dipolar cycloaddition
mechanism [4].
Ph
Ph
Ph
Ph
Ph
Ph
N
OH–
NH
NH
RCN
+
4a–i
N
H
R
ClO4
N
R
N
H
R
1
–
5a–i
HClO4
MeNO2,
6a–i
–
Ph
+
ClO4
Me
CHO
AcOH
Ph
Ph
O
N
H
Me
CN
N
H
4j
Me
N
CN
H
NH
Me
7
O
a R = 3,4-(EtO)2C6H3CH2, b R = MeOCH2CH2, c 1-AdCH2; d R =
,
O
H2N
e R = 4-BrC6H4, f R = 4-Me2NC6H4, g R = 4-(ClCH2)C6H4, h R =
, i R = Me
O
NO2
1493

In previous work [2, 3, 5], we established that APC 1 forms 9-phenylacridinium salts in acidic medium
at room temperature. Thus, in order to suppress the side reaction leading to 9-phenylacridinium perchlorate in
the synthesis of 3,4-dihydroquinazolinium perchlorates, we modified our previous procedure [2] and carried out
the synthesis of perchlorates 5a-i,k,l with a deficit of HClO4. The reaction was carried out in nitromethane at
reflux with equivalent amounts of the starting reagents and 70% perchloric acid, using gradual addition of the
acid into the reaction medium.
4-Formyl-3,5-dimethyl-1H-pyrrole-2-carbonitrile (4j) does not react with carbinol 1 under the same
reaction conditions (nitromethane solvent, equimolar amounts of reagents and perchloric acid). This nitrile
reacts with APC 1 in acetic acid as an aldehyde, giving the dihydrobenzoxazine 7.
An unusual course of the reaction of carbinol 1 with substituted 5-bromo-3-cyano-2(1H)-pyridones 4k,l,
leading to 3,4-dihydroquinazolinium perchlorates 5k,l and 4H-3,1-benzoxazinium perchlorates 8k,l was
established under our conditions. Partial hydrolysis of the nitrile group of pyridones 4k,l to a carboxyl group
with subsequent acylation of the amino group in APC 1 and heterocyclization to the perchlorates 8k,l is possible
in this case, besides the formation of perchlorates 5k,l [6]. However, no direct evidence has yet been obtained to
support this hypothesis.
–
Ph
Ph
Ph
Ph ClO4
OH–
NH
NH
R
R
+
CN
O
Br
Br
N
N
H
6k,l
N
H
4k,l
Me
O
N
H
Me
Ph
Ph
N
5k,l
1
HClO4
N
H
–
Ph
Ph ClO4
O
R
Ph
Ph
O
+
Br
OH–
N
H
N
O
N
H
Me
9k,l
8k,l
k R = Me, l R = CH2OMe
This is the first report of the preparation of perchlorates 5a-h,k,l and 8k,l and their corresponding bases,
namely, 3,4-dihydroquinazolines 6a-h,k,l and 4H-3,1-benzoxazines 9k,l. The characteristics of these new
products are given in Tables 1-3. The physicochemical properties of already reported 2-methyl-4,4-diphenyl-3,4-di-
hydroquinazolinium perchlorate (5i) and quinazoline 6i were given in our previous work [2].
The structures of products 6a-h,k,l and 9k,l were supported by the presence of stretching bands for N–H
bonds at 3150-3420 cm-1, C=N bonds at 1580-1620 cm-1, and C=O bonds at 1610-1690 cm-1 in the IR spectra of
these compounds. Stretching bands for a primary amino group were found for the base 6d at 3470, 3380, and
1590 cm-1.
The 1H NMR spectra of dihydroquinazolines 6a-c,g,h,k showed a signal for the secondary amino group
proton of the heterocycle as two singlets with the total intensity of 1H, confirming the existence of a tautomeric
equilibrium in DMSO-d6 solution between the 1H- and 3H-forms.
The initial decomposition of the molecular ions [M]+ of dihydroquinazolines 6a-d,k,l corresponds to our
previously proposed scheme [3], and is characterized by the loss of a phenyl radical and formation of cation Φ1,
which decomposes through two competing pathways: elimination of nitrile molecules (retrodiene
decomposition) and of diazirines RCN2H to give the corresponding even-electron species Φ2 and Φ3 (Table 3).
Cations such as Φ1–Φ3 are characteristic in the fragmentation of [M]+ of 3,4-dihydroquinazolines [3]. The
scheme below also gives cation Φ4 with greatest mass spectral intensity, which is formed upon the loss of a
methyl radical from the methoxymethyl substituent in dihydroquinazoline 6l.
1494

TABLE 1. Physicochemical Characteristics of the Compounds Synthesized
Found, %
——————
Com-
pound
Empirical
formula
Yield,
%
Mp, °С
Rf*
Calculated, %
C
H
N
Hal
С31H31ClN2O6
С23H23ClN2O5
С31H33ClN2O4
66.05
66.13
62.48
62.37
5.72
5.55
5.31
5.23
6.36
6.24
4.57
4.26
4.82
4.98
6.45
6.32
6.54 228-230
6.30
—
75
5a
5b
8.25
8.00
189-190
—
—
—
—
70
72
55
65
5c
69.67
69.85
5.18
5.26
6.42
6.65
>250
5d
5e
С27H22ClN3O6
62.61
62.37
8.38
8.09
7.01
6.82
>200
С26H20BrClN2O4
>220
3.85
3.73
57.51
57.85
5.31
5.19
21.52
21.37
(decomp.)
5f
5.31
5.20
С28H26ClN3O4
С27H22ClN2O4
С30H22ClN3O7
66.42
66.73
63.40
63.66
63.59
63.00
8.15
8.34
5.68
5.50
7.52
7.35
7.41
7.18
6.95
6.83
6.25
6.06
8.45
8.18
6.65
6.48
10.25
10.02
6.15
6.38
10.15
10.41
6.67
6.85
9.08
8.91
8.42
8.67
8.03
8.17
10.52
10.36
7.20
7.03
13.41
13.92
6.10
6.20
19.55
19.74
210–213
193–195
>210
—
—
73
71
65
53
15
72
75
70
65
80
75
93
50
85
70
60
38
75
80
73
45
60
5g
5h
5k
5l
4.75
4.35
4.01
3.88
—
С27H23BrClN3O5 55.62
3.81
3.96
4.21
4.10
6.31
6.54
6.32
6.48
7.32
7.46
5.32
5.05
4.50
4.36
6.51
6.24
5.01
5.18
4.31
4.49
4.35
4.58
4.82
4.70
5.35
5.72
3.62
3.79
3.79
3.93
4.18
4.36
>220
—
55.45
С28H25BrClN3O6 54.45
18.55
18.76
>250
—
54.70
80.28
80.49
80.55
80.67
85.82
86.07
77.02
77.31
71.15
71.08
83.08
83.34
79.55
79.30
76.68
76.42
66.59
66.95
65.21
65.38
80.24
79.97
6a
6b
6c
6d
6e
6f
С31H30N2O2
С23H22N2O
С31H32N2
—
—
132-134
139-140
216-218
253-256
123-126
198-200
151-153
134-136
232-233
240-242
179-181
0.19
0.38
0.22
0.50
0.75
0.22
0.85
0.43
0.06
0.13
0.85
—
—
—
С27H21N3O2
С26H19BrN2
С28H25N3
18.45
18.19
—
6g
6h
6k
6l
С27H21ClN2
С30H21N3O3
С27H22BrN3O
С28H24BrN3O2
С27H23N3O
8.51
8.67
—
16.84
16.50
15.38
15.53
7
—
8k
8l
С27H22BrClN2O6 55.61
4.93
4.78
4.46
4.55
5.52
5.77
5.62
5.44
5.85
5.71
9.51
9.26
19.54
19.69
18.93
18.73
16.71
16.46
15.75
15.50
>150
(decomp.)
55.36
С28H24BrClN2O7 54.75
>250
—
54.61
66.96
66.81
65.38
65.25
81.10
80.78
9k
9l
С27H21BrN2O2
С28H23BrN2O3
С33H34N2O2
С21H22N2
238-240
241-243
146-149
140-141
0.51
0.17
0.65
0.50
4.35
4.50
6.72
6.98
7.05
7.33
10a
13f
—
—
83.67
83.40
_______
*Eluent – acetone–benzene, 1:9.
1495

Ph
NH
Ф2
m/z 180
Ph
+
+·
–RCN
(RDA)
Ph
Ph
–Ph·
NH
N
+
N
–
R
N
R
N
R
N
H
Ph
Ф1
[M]+
6a–d,k,l
–Me·
m/z (M–77)
+
for 6l
Ph
Ph
+
OH
NH HC
Ф3
Br
m/z 165
N
Ф4
m/z 498
O
N
Me
H
The first step in the fragmentation of the [M]+ ion of benzoxazines 9k,l is decomposition of the
heterocycle, which is characteristic for decomposition of the [M]+ ion of 4H-3,1-benzoxazine derivatives [7-9].
This step leads to formation of cation Φ5, which then eliminates a hydrogen atom or phenyl radical to give
cations Φ6 or Φ7.
+·
Ph
Ph
Ph
Ph
O
Ph –H·
+·
–C7H2BrNO2R·
NH
Ф6
R
m/z 257
Ph
Ph
+
Br
N
+·
–Ph·
NH2
Ф5
m/z 258
[M]+
9k,l
O
N
H
Me
H
NH
Ф7
m/z 181
TABLE 2. IR Spectra of Salts 5a-h,k,l and 8k,l
, cm–1
Compound
+
–
NH
NH
ClO4
Others
3300, 3210, 1630
3300, 3230, 1640
3300, 3200, 1620
3350, 3190, 1630
3170, 1620
1130, 1120, 1030
1140, 1100, 1630
1130, 1090, 1025
1100, 1060, 1020
1100, 1050, 1020
1120, 1050,
—
—
5a
5b
5c
5d
5e
5f
—
+
3280 (NH3 )
—
2300 (NH+)
—
3180, 1580
3180, 1620
1130, 1090, 1010
1110, 1050
5g
5h
5k
5l
3150, 1630
1370, 1520 (NO2)
1635 (C=O)
1620 (C=O)
1630 (C=O)
1640 (C=O)
3250, 3170, 1640
3200, 3150, 1630
2480, 1665, (NH+)
2700, 1645 (NH+)
1100, 1090, 1010
1100, 1075, 1010
1020, 1090, 1010
1105, 1081, 1030
8k
8l
1496

It was of interest to carry out alkylation and acylation reactions with a series of dihydroquinazoline
products undertaken in our previous work [1, 2], in order to determine the reaction pathways and to possibly
utilize synthetically one of the tautomeric forms (A or D).
The methylation of dihydroquinazolines 6a,b,f,i with excess dimethyl sulfate in aqueous medium in the
presence of sodium bicarbonate with subsequent treatment with aqueous sodium hydroxide (see the review by
Weygand [11], p. 463) leads to N,N-dimethylation products 10-13.
Ph
Ph
Ph
N
Me
OEt
OEt
from 6а
N
Me
10a
Ph
Ph
Ph
(3)
Me
1) Me2SO4
NaHCO3
2) NaOH
(2)
N Me
H
from 6i
N
(1)
C Me
O
(1)
N
C Me
NH
(2)
6a,b,f,i
(3)
Me
O
Me
12i
11i
Ph
Ph
(2)
N Me
H
from 6f
from 6b
NH
(1)
Me
13f
mixture of oligomers
Thus, 2-(3',4'-diethoxybenzyl)-4,4-diphenyl-3,4-dihydroquinazoline (6a) gives a dimethylation product
with retention of the quinazoline system, namely, 2-(3,4-diethoxybenzylidene)-1,3-dimethyl-4,4-diphenyl-
1,2,3,4-tetrahydroquinazoline (10a). The 1H NMR spectrum indicates that this compound in trifluoroacetic acid
solution exists as a 1:1 mixture of two geometric isomers. This conclusion is also supported by the finding of
four singlets for the two N–CH3 groups at 1.95, 2.92, 3.30, and 3.90 ppm, as well as two methine proton singlets
at 5.60 and 5.85 ppm in the spectrum with the total intensity of 6H and 1H, respectively. The IR spectrum lacks
NH group stretching bands (Table 3). This pathway for the reaction is determined, firstly, by the presence of an
active exocyclic methylene group and, secondly, by the formation of a conjugated N,N-di-substituted styryl
fragment in the final product 10a. An analogous product, namely, 1,3-dimethyl-2-(4-nitro-benzylidene)-4,4-
diphenyl-1,2,3,4-tetrahydroquinazoline, was obtained in our previous work in the dimethyl sulfate methylation
of 2-(4-nitrobenzyl)-4,4-diphenyl-3,4-dihydroquinazoline [2].
3,4-Dihydroquinazolines 6i,f, which lack an active methylene group at C-2 in the heterocycle, undergo
methylation with ring opening.
Methylation of 2-methyl-4,4-diphenyl-3,4-dihydroquinazoline (6i) gives the dimethylation product 11i.
The 1H NMR spectrum of this compound in DMSO-d6 shows two broadened NH proton singlets and signals for
three methyl groups, each of which appears as two singlets. This type of spectrum indicates a dynamic
equilibrium in solution between two structural isomers, namely, N-methyl-N-{2-[(methylamino)-
(diphenyl)methyl]phenyl}acetamide (11i) and N-methyl-N-{2-[(methylamino)phenyl](diphenyl)methyl}-
acetamide (12i), which occurs by means of acetyl group migration between N-1 and N-3 atoms through the
tetrahydroquinazoline species A' [13]. Comparison of the integral intensity of the methyl group proton signals
in the 1H NMR spectrum indicates a 3:2 ratio of isomers 11i and 12i.
1497

Ph
Ph
N Me
Me
12i
11i
N
OH
Me
A'
Only one of the two open forms (11i or 12i) exists in the crystalline state, because the IR spectrum of
crystals of this product shows only one C=O absorption band (amide 1, at 1635 cm-1) and one narrow NH
stretching band at 3300 cm-1 [12].
Elemental analysis and spectral data (Tables 1 and 3) indicate that the reaction of 2-(4-dimethyl-
aminophenyl)-4,4-diphenyl-3,4-dihydroquinazoline (6f) with dimethyl sulfate proceeds through decomposition
of the dihydroquinazoline system and concludes with formation of N-methyl-2-[(methylamino)-
(diphenyl)methyl]aniline (13f). The lack of C=O group stretching bands in the IR spectrum of diamine 13f
indicates that the decomposition of excess dimethyl sulfate by aqueous alkali involves not only opening of the
heterocyclic system but also hydrolysis of the amide group.
Methylation of 2-(2-methoxyethyl)-4,4-diphenyl-3,4-dihydroquinazoline (6b) under the conditions
given by Weygand [11] leads to a mixture of unidentified oligomers.
The mass spectra of methylation products 10-13 contain molecular ion peaks [M]+ with the charge of +1
(Table 3). The initial fragmentation step of the [M]+ ions of products 10a and 13f is loss of an imine molecule
(CH2=NH) leading to ions Φ1, which differs significantly from the initial mass-spectral decomposition of [M]+
of dihydroquinazolines 6a-d.
[M]+
10a, 13f
– CH2=NH
for 13f
for 10a
Ph
Ph
+·
+·
Ph
Ph
H
N
Me
N
OEt
OEt
Me
H
Ф1
m/z 273
Ф1
m/z 461
Attempts to carry out the acylation of dihydroquinazolines 6a-g,i using acid halides or acetic anhydride
were unsuccessful. No acylation of these compounds was detected [11].
Thus, we have shown that the nature of the substituent at C-2 atom of the heterocycle has a considerable
effect on the direction of methylation of 3,4-dihydroquinazolines using dimethyl sulfate. In the future, we plan
to use a broad range of 2-alkyl-, 2-aryl-, and 2-hetaryl-3,4-dihydroquinazolines in alkylation reactions and to
continue our investigation of both the substituent and alkylating agent effect on the direction of the reaction.
EXPERIMENTAL
The IR spectra were recorded on a Specord IR-75 spectrometer at room temperature in vaseline mull.
The 1H NMR spectra were recorded on a Bruker DRX-500 spectrometer at 500 MHz. The spectra of compounds
6a,b were recorded in (CD3)2CO, while the spectrum of compound 6c was recorded in trifluoroacetic acid on a
Tesla BS spectrometer at 60 MHz with TMS as internal standard. The mass spectra were recorded on a Varian
1498

1499

1500

CH-6 spectrometer with direct sample inlet inlet into the ionization chamber at 50-180°C and electron ionization
energy 70 eV. The elemental analysis was carried out on a Hewlett-Packard HP-185B C,H,N-analyzer. The
melting points were determined on a Thiele melting-point apparatus. The reaction course was followed by thin-
layer chromatography on Silufol UV-254 plates with iodine vapor visualization.
2-(3,4-Diethoxybenzyl)-4,4-diphenyl-3,4-dihydroquinazolinium Perchlorate (5a). 70% Perchloric
acid (0.25 ml, 2.5 mmol) was added dropwise to a mixture of (3,4-diethoxyphenyl)acetonitrile (4a) (0.51 g,
2.5 mmol) and APC 1 (0.67 g, 2.5 mmol) in nitromethane (5 ml) at reflux. After 60 min, the reaction mixture
was cooled on an ice bath. Salt 5a was precipitated by adding ether and filtered off. Yield 1.06 g (75%).
Colorless crystals.
Salts 5b-i were obtained analogously.
2-(5-Bromo-4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)-4,4-diphenyl-3,4-dihydroquinazolinium
perchlorate (5k) and 2-(5-bromo-4,6-dimethyl-2-oxo-1,2-dihydropyridin-3-yl)-4,4-diphenyl-4H-3,1-benz-
oxazinium perchlorate (8k) were obtained analogously. Perchlorate 8k precipitated from the reaction mixture
upon cooling on an ice bath, while the perchlorate 5k was precipitated by adding ether.
Salts 5l and 8l were obtained and isolated analogously.
Bases 6a-i,k,l and 9k,l were obtained by deprotonation of the corresponding salts in 25% aqueous
ammonium hydroxide [3] and recrystallization from ethanol. The bases obtained form colorless crystals.
2-[(5-Cyano-2,4-dimethyl)pyrrol-3-yl]-4,4-diphenyl-1,4-dihydro-2H-3,1-benzoxazine (7). Formyl nitrile
4j (0.37 g, 2.5 mmol) was added to a solution of APC 1 (0.67 g, 2.5 mmol) in glacial acetic acid (5 ml) cooled to
0°C. The mixture was stirred at room temperature for 1 h. The colorless crystalline precipitate was filtered off
and washed with 1:3 ethanol–water.
2-(3,4-Diethoxybenzylidene)-1,3-dimethyl-4,4-diphenyl-1,2,3,4-tetrahydroquinazoline (10a). (2-(3,4-
Di-ethoxybenzyl-4,4-diphenyl-3,4-dihydroquinazoline (6a) (1.03 g, 2.22 mmol) was added to a suspension of
sodium bicarbonate (2.65 g, 31.55 mmol) in water (4 ml). Then dimethyl sulfate (3.52 g, 28.00 mmol) was
added. The reaction was carried out with stirring on a water bath at 30-35°C for 4 h. At the end of the reaction,
excess dimethyl sulfate was decomposed by raising the temperature of the reaction mixture to 50-55°C and
maintaining for about 30 min at this temperature. The methyl sulfate salt was then decomposed by heating the
reaction mixture with excess 5% aqueous sodium hydroxide on a steam bath. The reaction mixture was cooled
and the organic fraction was extracted with chloroform. After distilling off the solvent, the residue was
recrystallized from ethanol to give tetrahydroquinazoline 10a. Yield 0.49 g (45%). Colorless crystals.
Compound 13f was obtained analogously.
Mixture of N-methyl-N-{2-[(methylamino)(diphenyl)methyl]phenyl}acetamide (11i) and
N-methyl-N-{2-[(methylamino)phenyl](diphenyl)methyl}acetamide (12i) was obtained analogously. Yield
0.50 g (65%). Colorless crystals; mp 139-141°C (EtOH), Rf 0.45 (1:9 acetone–benzene). IR spectrum, , cm-1:
1
3300 (NH), 1635 (C=O). H NMR spectrum (DMSO-d6), , ppm: 0.75 (1.8Н, s, СН3(2) (11i)); 1.60 (1.2Н, s,
СН3(2) (12i)); 1.85 (1.2Н, s, СН3(3) (12i)); 1.90 (1.8Н, s, СН3(3) (11i)); 2.55 (1.2Н, s, СН3(1) (12i)); 2.65
(1.8Н, s, СН3(1) (11i)); 2.76 (0.6Н, br. s, NH (11i)); 3.20 (0.4Н, br. s, NH (12i)); 7.00-7.51 (14Н, m, H Ar
(11i+12i)). Mass spectrum, m/z (Irel, %): 344 [М]+ (25). Found, %: С 80.05; H 6.65; N 8.19. C23H24N2O.
Calculated, %: С 80.23; H 6.97; N 8.14.
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