Synthesis and structure of some 2-trifluoromethyl-substituted hetarylmethylidene(or propylidene)anilines

Article abstract of DOI:10.1023/A:1023910709552

The reaction of furan, thiophene, pyridine, and also furylacryloyl aldehydes with 2-trifluoromethylanilines has been studied in the presence of molecular sieves and a series of new heterocyclic aldimines has been synthesized. The molecular and crystalline structure of some of them were determined by X-ray structural analysis.

Full text of DOI:10.1023/A:1023910709552

Chemistry of Heterocyclic Compounds, Vol. 39, No. 3, 2003
SYNTHESIS AND STRUCTURE OF SOME
2-TRIFLUOROMETHYL-SUBSTITUTED
HETARYLMETHYLIDENE(OR PROPYLIDENE)ANILINES
I. Iovel, L. Golomba, S. Belyakov, J. Popelis, A. Gaukhman, and E. Lukevics
The reaction of furan, thiophene, pyridine, and also furylacryloyl aldehydes with
2-trifluoromethylanilines has been studied in the presence of molecular sieves and a series of new
heterocyclic aldimines has been synthesized. The molecular and crystalline structure of some of them
were determined by X-ray structural analysis.
Keywords: heterocyclic Schiff's bases, 2-trifluoromethylaniline, molecular sieves.
Previously we developed an efficient method [1-4] for the synthesis of a broad range of azomethines by
the condensation of heterocyclic aldehydes with amines in the presence of molecular sieves. In these processes
the latter plays the role not only of a dehydrating agent but also of an optimal acid catalyst, which does not lead
(unlike in the majority of homogeneous systems) to the resinification of the acidophobic furan and thiophene
substrates and does not form salts at the ring nitrogen atom of pyridine compounds, which usually prevents
further conversion. Using this method a series of syntheses has been carried out in the present work (Scheme 1)
and the corresponding heterocyclic aldimines with a trifluoromethyl substituent have been obtained. These are
potentially biologically active compounds.
By reacting furfural, thiophene aldehyde, and their 5-methyl derivatives 1a-d, 2-, 3-, and 4-pyridine
aldehydes 2a-c, and also furylacroleins 3a-c with 2-trifluoromethylaniline in the presence of molecular sieve
4A, the corresponding products N-(hetarylmethylidene or hetarylpropylidene)-2-trifluoromethylanilines 4a-d,
5a-c, and 6a-c (Table 1) were synthesized. Benzene was used as solvent. In difference to 3- and
4-trifluoromethylanilines studied previously in [1-4] (the condensation of which with aldehydes occurs even at
room temperature), 2-trifluoromethylaniline reacts with all the carbonyl compounds studied only on heating
(80°C). Probably the CF3 group in a position close to the nitrogen atom of the aromatic amine impedes
condensation. The reactivity of the aldehydes, which are derivatives of five-membered O and S heterocycles
(except for 5-methylfurylacrolein), is greater than that of the pyridine aldehydes. All the compounds obtained
1
were yellow crystalline or liquid substances, their H NMR spectra, mass spectra, and elemental analyses
corresponded to the structure of the desired aldimines.
Monocrystals of the new compounds 4d and 6c were obtained and were investigated by X-ray
diffraction with the aim of establishing their molecular and crystal structure (Fig. 1). The principal
crystallographic data, coordinates of non-hydrogen atoms, and some geometric characteristics of the studied
aldimines are given in Tables 2-6. The molecules of the compounds have the trans (4d) and trans-E
configuration (6c). The planes of the phenyl and heterocyclic fragments are mutually inclined in the molecules
at 40.0(3)° (4d) and 29.1(5)° (6c).
__________________________________________________________________________________________
Latvian Institute of Organic Synthesis, Riga LV-1006; e-mail: iovel@osi.lv. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 3, pp. 361-370, March, 2003. Original article submitted October 26, 2002.
318
0009-3122/03/3903-0318$25.00©2003 Plenum Publishing Corporation

TABLE 1. Characteristics of the Compounds Synthesized
Found, %
——————
Reaction
time, h
Empirical
formula
mp, °С*
[bp, °С]
Aldimine
Calculated, %
Yield, %
70
C
H
N
S
6
C12H8F3NO
60.16
60.26
3.30
3.37
5.76
5.86
55-56
4a
[80° (0.5 mm Hg), subl.]
6
6
6
C13H10F3NO
C12H8F3NS
C13H10F3NS
61.41
3.76
5.48
27
56
73
61
4b
4c
4d
61.66
3.98
5.53
56.70
56.47
3.08
3.16
5.37
5.49
12.51
12.56
75-76
57.91
3.73
5.20
11.88
62-63
57.98
3.74
5.20
11.91
[70° (0.1 mm Hg), subl.]
5a*2
5b*2
5c
8
8
C13H9F3N2
C13H9F3N2
C13H9F3N2
C14H10F3NO
C15H12F3NO
C14H9F3N2O3
98
98
51
74
75
72
8
62.28
62.40
3.58
3.63
11.12
11.19
45-46
65-66
6
63.41
3.71
5.10
6a
63.40
3.80
5.28
6b*2
15
6
64.02
64.52
4.73
4.33
4.46
5.02
54.23
2.79
8.91
102-103
6c
54.20
2.92
9.03
_______
* Recrystallization solvent: 4c, 6c ethyl acetate–hexane and 4d, 5c, and 6a hexane.
*2 Oily liquid.

Scheme 1
3
4
F3C
3'
5
4'
R
C
H
N
X
R
CHO
CHO
X
5'
6'
4a–d
1a–d
F3C
F3C
4
H2N
3
2
5
C
H
N
6
N
N
4A MS,
C6H6,
5a–c
80 oC
2a–c
F3C
R
C
H
C
H
C
N
O
H
g
R
C
H
C CHO
O
3a–c
a
b
H
6a–c
1, 4 a X = O, R = H, b X = O, R = Me; c X = S, R = H; d X = S, R = Me;
3, 6 a R = H, b R = Me, c R = NO2; position of substituent 2, 5 a 2-, b 3-, c 4-
a
b
Fig. 1. Spatial models of the molecules of compounds 4d (a) and 6c (b) with numbering of atoms
and ellipsoids of thermal vibrations.
320

Fig. 2. Projection of the crystal structure of compound 4d along the z axis.
Fig. 3. Projection of the crystal structure of compound 6c along the y axis.
321

The more flattened 6c molecules are packed in the crystal parallel to the crystal (1 0 1) plane. In the
highly symmetrical crystal structure of 4d the packing of the molecules is more loose and plane-parallel stacks
of molecules were not observed (Figs. 2 and 3).
TABLE 2. Crystallographic Data for Compounds 4d and 6c
Characteristic
Empirical formula
Molecular weight
Color
4d
6c
C13H10F3NS
269.29
Yellow
C14H9F3N2O3
310.23
Orange
Crystal size, mm
Crystal system
Space group
0.15×0.27×0.27
Tetragonal
P 43
0.08×0.15×0.37
Monoclinic
P 21/c
Lattice parameters
a, Å
9.7828(3)
—
13.8724(5)
—
1327.63(7)
4
1.347(1)
0.26
7.9451(4)
14.4700(7)
11.9143(5)
96.305(3)
1361.45(11)
4
b, Å
c, Å
β, deg
Unit cell volume, V, Å3
Number of molecules in unit cell, Z
Density, d, g/cm3
Absorption coefficient, µ, mm-1
Number
1.514(1)
0.13
Independent reflections
reflections with I > 3σ(I)
refinement parameters
Final reliability factor, R
1615
1266
203
3540
1523
220
0.035
0.046
TABLE 3. Coordinates of Non-hydrogen Atoms and Their Equivalent
Isotropic Thermal Parameters in Structure 4d
Atom
x
y
z
Ueq
S(1)
0.29288(8)
0.1548(3)
0.0942(3)
0.1686(3)
0.2943(4)
0.1154(3)
0.1774(4)
0.3877(3)
0.1324(5)
0.3556(4)
0.2026(5)
-0.1012(6)
0.3259(6)
-0.0457(4)
-0.0189(7)
0.3912(7)
0.3890(4)
0.1190(6)
0.21221(8)
0.0014(3)
-0.1076(3)
0.2355(3)
0.3837(4)
0.1224(3)
-0.2141(3)
-0.1011(4)
0.3695(4)
-0.2154(4)
0.4528(4)
-0.2249(5)
-0.2117(5)
-0.1132(4)
-0.3281(5)
0.4392(9)
-0.3189(5)
-0.3232(4)
0.24790(6)
0.12345(18)
0.0711(2)
0.1621(2)
0.2756(3)
0.1071(2)
0.0394(3)
0.0248(4)
0.1576(4)
0.1524(3)
0.2222(4)
0.0059(4)
0.0584(5)
0.0545(3)
-0.0263(4)
0.3497(5)
0.0200(5)
-0.0105(4)
0.0605(4)
0.0558(11)
0.0558(14)
0.0573(14)
0.0690(17)
0.0582(14)
0.0689(17)
0.132(2)
N(1)
C(7)
C(2)
C(5)
C(6)
C(8)
F(1)
C(3)
F(3)
0.081(2)
0.130(2)
0.084(2)
0.092(3)
0.097(3)
0.0712(18)
0.101(3)
0.105(4)
0.169(3)
0.091(3)
C(4)
C(11)
C(13)
C(12)
C(10)
C(14)
F(2)
C(9)
322

TABLE 4. Coordinates of Non-hydrogen Atoms and Their Equivalent
Isotropic Thermal Parameters in Structure 6c
Atom
O(1)
F(2)
F(3)
x
y
z
Ueq
0.9051(2)
0.4074(3)
0.4220(3)
0.6329(3)
0.4874(3)
0.9732(4)
0.9241(4)
0.4127(4)
0.9138(4)
0.9648(4)
0.7554(4)
0.8283(4)
0.8126(4)
0.4908(4)
0.4122(4)
0.5664(4)
0.4871(5)
0.5640(4)
1.0726(4)
0.9591(4)
0.6468(3)
1.0672(4)
0.02621(14)
0.11147(14)
0.07046(13)
0.18929(16)
0.2268(2)
0.11319(19)
0.1681(2)
0.2904(2)
-0.0975(2)
-0.0066(2)
0.2096(2)
-0.14221(18)
0.1454(2)
0.1274(2)
0.3832(2)
0.2569(2)
0.4134(2)
0.3515(2)
0.1316(2)
-0.1243(2)
0.09652(14)
0.0537(2)
0.14033(14)
-0.52929(14)
-0.35771(15)
-0.21239(18)
-0.3953(2)
0.1358(2)
0.0380(3)
-0.4720(2)
0.2692(3)
0.2437(3)
-0.1378(2)
0.1975(2)
-0.0488(2)
-0.4276(2)
-0.4463(3)
-0.29038(19)
-0.3435(3)
-0.2662(3)
0.2339(3)
0.0584(10)
0.0888(12)
0.0867(12)
0.0608(13)
0.0539(14)
0.0567(15)
0.0615(16)
0.0602(15)
0.0754(17)
0.0624(16)
0.0602(16)
0.0919(17)
0.0579(16)
0.0620(16)
0.0683(18)
0.0553(14)
0.0675(17)
0.0622(16)
0.0709(19)
0.1050(18)
0.0988(14)
0.075(2)
N(1)
C(10)
C(2)
C(6)
C(11)
N(2)
C(5)
C(8)
O(2)
C(7)
C(15)
C(12)
C(9)
C(13)
C(14)
C(3)
O(3)
F(1)
0.3663(2)
-0.4334(2)
0.3031(3)
C(4)
TABLE 5. Main Bond Lengths (d) and Values of Valence Angles (θ) in
Molecules of Compound 4d
Bond
1
d, Å
2
Angle
3
θ, deg
4
S(1)–C(2)
1.716(4)
C(2)–S(1)–C(5)
C(7)–N(1)–C(6)
N(1)–C(7)–C(8)
N(1)–C(7)–C(12)
C(8)–C(7)–C(12)
S(1)–C(2)–C(6)
S(1)–C(2)–C(3)
C(6)–C(2)–C(3)
S(1)–C(5)–C(4)
S(1)–C(5)–C14
C(4)–C(5)–C14
N(1)–C(6)–C(2)
C(7)–C(8)–C(13)
C(7)–C(8)–C(9)
C(13)–C(8)–C(9)
C(2)–C(3)–C(4)
C(5)–C(4)–C(3)
C(12)–C(11)–C(10)
C(8)–C(13)–F(1)
C(8)–C(13)–F(3)
C(8)–C(13)–F(2)
91.8(2)
S(1)–C(5)
N(1)–C(7)
N(1)–C(6)
C(7)–C(8)
C(7)–C(12)
C(2)–C(6)
C(2)–C(3)
C(5)–C(4)
C(5)–C(14)
C(8)–C(13)
C(8)–C(9)
F(1)–C(13)
C(3)–C(4)
F(3)–C(13)
C(11)–C(12)
C(11)–C(10)
C(13)–F(2)
C(10)–C(9)
C(6)–H(6)
C(3)–H(3)
1.721(4)
1.420(4)
1.265(5)
1.393(6)
1.389(6)
1.442(5)
1.359(6)
1.346(8)
1.501(8)
1.477(8)
1.395(6)
1.324(8)
1.391(8)
1.336(10)
1.394(7)
1.366(10)
1.329(7)
1.368(10)
0.93(5)
118.9(3)
118.6(3)
121.7(4)
119.6(4)
121.4(3)
110.2(3)
111.2(3)
128.4(4)
120.7(6)
128.1(6)
120.8(3)
120.4(4)
119.3(4)
120.2(5)
114.0(5)
112.9(4)
120.6(5)
113.6(5)
112.8(6)
111.9(5)
0.94(8)
323

TABLE 5 (continued)
1
2
3
4
C(4)–H(4)
0.98(6)
F(1)–C(13)–F(3)
F(1)–C(13)–F(2)
F(3)–C(13)–F(2)
C(7)–C(12)–C(11)
C(11)–C(10)–C(9)
C(8)–C(9)–C(10)
105.4(6)
107.0(6)
105.6(6)
119.7(5)
120.2(5)
120.7(5)
C(11)–H(11)
C(12)–H(12)
C(10)–H(10)
C(14)–H(14A)
C(14)–H(14B)
C(14)–H(14C)
C(9)–H(9)
0.94(6)
1.12(6)
0.97(8)
0.88(12)
1.01(13)
0.96(13)
0.93(6)
TABLE 6. Main Bond Lengths (d) and Valence Angles (θ) in Molecules of
Compound 6c
Bond
O(1)–C(2)
d, Å
1.373(3)
Angle
θ, deg
104.9(2)
C(2)–O(1)–C(5)
C(8)–N(1)–C(9)
C(11)–C(10)–C(15)
C(11)–C(10)–C(9)
C(15)–C(10)–C(9)
O(1)–C(2)–C(6)
O(1)–C(2)–C(3)
C(6)–C(2)–C(3)
C(2)–C(6)–C(7)
C(10)–C(11)–C(12)
C(5)–N(2)–O(2)
C(5)–N(2)–O(3)
O(2)–N(2)–O(3)
O(1)–C(5)–N(2)
O(1)–C(5)–C(4)
N(2)–C(5)–C(4)
N(1)–C(8)–C(7)
C(6)–C(7)–C(8)
F(2)–C15–F(3)
F(2)–C(15)–C(10)
F(2)–C(15)–F(1)
F(3)–C(15)–C(10)
F(3)–C(15)–F(1)
C(10)–C(15)–F(1)
C(11)–C(12)–C(13)
N(1)–C(9)–C(10)
N(1)–C(9)–C(14)
C(10)–C(9)–C(14)
C(12)–C(13)–C(14)
C(9)–C(14)–C(13)
C(2)–C(3)–C(4)
C(5)–C(4)–C(3)
O(1)–C(5)
F(2)–C(15)
F(3)–C(15)
N(1)–C(8)
N(1)–C(9)
C(10)–C(11)
C(10)–C(15)
C(10)–C(9)
C(2)–C(6)
C(2)–C(3)
C(6)–C(7)
C(11)–C(12)
N(2)–C(5)
N(2)–O(2)
N(2)–O(3)
C(5)–C(4)
C(8)–C(7)
C(15)–F(1)
C(12)–C(13)
C(9)–C(14)
C(13)–C(14)
C(3)–C(4)
C(6)–H(6)
C(11)–H(11)
C(8)–H(8)
C(7)–H(7)
C(12)–H(12)
C(13)–H(13)
C(14)–H(14)
C(3)–H(3)
C(4)–H(4)
1.357(3)
1.337(3)
1.330(3)
1.278(3)
1.411(3)
1.383(4)
1.489(4)
1.405(3)
1.429(4)
1.364(4)
1.326(4)
1.378(4)
1.419(4)
1.218(3)
1.235(3)
1.339(4)
1.444(4)
1.328(3)
1.373(4)
1.401(4)
1.378(4)
1.399(4)
0.90(4)
120.0(2)
119.4(2)
119.9(3)
120.6(2)
117.9(2)
109.8(2)
132.2(3)
126.7(3)
121.0(3)
119.5(2)
115.5(3)
124.9(3)
116.0(2)
112.5(3)
131.5(3)
121.1(3)
122.8(3)
105.3(2)
112.3(2)
105.5(2)
114.7(2)
105.9(2)
112.5(2)
119.7(3)
118.0(2)
123.7(2)
118.1(2)
120.5(3)
120.9(3)
107.1(3)
105.7(3)
1.01(3)
1.01(3)
0.92(3)
0.94(3)
0.95(3)
0.97(3)
1.01(4)
0.93(3)
324

EXPERIMENTAL
1
The H NMR spectra were investigated on a Varian Mercury (200 MHz) spectrometer for solutions in
CDCl3, internal standard was TMS. The mass spectra were obtained on an HP 6890 GC/MS chromato-mass
spectrometer fitted with an HP 5 MS capillary column (30.0 m × 250 µm × 0.25 µm), with temperature
programing from 70 to 260°C (10°C/min).
Before use benzene was distilled over CaH2. 5-Methyl-2-thiophenecarbaldehyde was synthesized by the
method of [5]. The remaining reagents used in the work were obtained from Fluka, Merck, and Acros. Aldehyde
3c was recrystallized from benzene, and other aldehydes were purified by vacuum distillation, after which their
properties corresponded to literature data. 2-Trifluoromethylaniline was used without additional purification.
Molecular sieves 4A (VEB Laborchemie Apolda) were used in the work.
General Procedure for the Synthesis of Aldimines 4a-d, 5a-c, and 6a-c. Dry benzene (10 ml) and the
initial aldehyde and amine (about 5 mmol) were placed in a round-bottomed flask with a reflux condenser, then
freshly calcined molecular sieve (5 g) was added and the mixture was heated on a water bath at 80°C in an
atmosphere of argon, taking samples periodically and analyzing them by TLC and GLC-MS. Practically
complete conversion into the appropriate products occurred during a definite time depending on the substrates
(Table 1). At the end of the reaction the sieve was filtered off, washed with benzene, and the filtrate was
evaporated at reduced pressure (40°C, 15 mm Hg). The insignificant quantity of starting materials was removed in
vacuum (45-50°C, 0.1 mm Hg). The products were oily substances or crystalline compounds. The solid substances
were purified by vacuum sublimation or by recrystallization and their 1H NMR spectra were recorded.
X-Ray Structural Investigation. Monocrystals of aldimines 4d and 6c were obtained by slow
crystallization from a hexane–ethyl acetate, 1:1 mixture. The analysis was carried out at 25°C on a Nonius
Kappa CCD automatic diffractometer (MoKα radiation, 2θmax = 55°C). The structures of the indicated
compounds were solved by the direct method of [6] and refined by the least squares method in a full matrix
anisotropic approach. All the hydrogen atoms were found from a difference synthesis and were refined
isotropically. All the calculations were carried out using the set of programs from [7].
N-(2-Furylmethylidene)-2-trifluoromethylaniline (4a). Mass spectrum, m/z (Irel, %): 240 (12,
[M + H]+), 239 (100, M+), 238 (68 [M-H]+), 220 (7,[M-F]+), 210 (14, [M-HCO]+), 191 (9), 183 (5), 172 (10,
[M-Fur]+), 170 (19, [M-CF3]+), 145 (59, [C6H4CF3]+), 125 (14), 115 (7), 95 (19), 75 (18), 68 (10, FurH+),
51 (18). 1H NMR spectrum, , ppm (J, Hz): 6.56 (1H, dd, J = 5.0, J = 2.0, H-4); 7.00 (1H, d, J = 7.6, H-3'); 7.04
δ
(1H, d, J = 5.0, H-3); 7.24 (1H, dd, J = 5.0, J = 2.0, H-5); 7.28 (1H, t, J = 7.6, H-5'); 7.52 (1H, t, J = 7.6, H-4');
7.66 (1H, d, J = 7.6, H-6'); 8.15 (1H, s, CH=N).
N-(5-Methyl-2-furylmethylidene)-2-trifluoromethylaniline (4b). Mass spectrum, m/z (Irel, %):
254 (14, [M+H]+), 253 (100, M+), 252 (47, M-H]+), 238 (9, [M-Me]+), 234 (6, [M-F]+). 218 (18), 211 (6),
210 (22, [M-MeCO]+), 191 (20), 190 (12), 184 (14), 183 (5), 172 (10), 145 (58, [C6H4CF3]+), 125 (15), 95 (22),
1
81 (14), 75 (18), 69 (9), 53 (29), 52 (13), 51 (24). H NMR spectrum, , ppm (J, Hz): 2.41 (3H, s, CH3); 6.17
δ
(1H, dd, J = 3.4, J = 1.2, H-4); 6.89 (1H, d, J = 3.4, H-3); 6.97 (1H, d, J = 8.0, H-3'); 7.22 (1H, t, J = 8.0, H-5');
7.50 (1H, t, J = 8.0, H-4'); 7.64 (1H, d, J = 8.0, H-6'); 8.02 (1H, s, CH=N).
N-(2-Thienylmethylidene)-2-trifluoromethylaniline (4c). Mass spectrum, m/z (Irel, %): 256 (16,
[M+H]+), 255 (89, M+), 254 (100, [M-H]+), 236 (6, [M-F]+), 186 (6, [M-CF3]+), 172 (5), 145 (48, [C6H4CF3]+),
125 (12), 95 (17), 84 (7, [ThH]+), 75 (12), 69 (10), 58 (7), 51 (6). 1H NMR spectrum, , ppm (J, Hz): 7.04 (1H,
δ
d, J = 8.0, H-3'); 7.13 (1H, dd, J = 5.2, J = 3.8, H-4); 7.2-7.3 (2H, m, H-4', H-5'); 7.4-7.6 (2H, m, H-3, H-5); 7.66
(1H, d, J = 8.0, H-6'); 8.45 (1H, s, CH=N).
N-(5-Methyl-2-thienylmethylidene)-2-trifluoromethylaniline (4d). Mass spectrum, m/z (Irel %):
270 (15, [M+H]+); 269 (85, M+), 268 (100, [M-H]+), 250 (5, [M-F]+), 248 (5), 200 (6, [M-CF3]+), 172 (6),
145 (40, [C6H4CF3]+), 125 (9), 97 (26, [MeTh]+), 95 (17), 77 (11), 69 (12), 53 (11), 51 (8). H NMR spectrum,
1
, ppm (J, MHz): 2.54 (3H, d, J = 1.0, CH3); 6.80 (1H, dd, J = 3.8, J = 1.0, H-4); 7.03 (1H, d, J = 7.8, H-3');
δ
7.24 (1H, t, J = 7.8, H-5'); 7.31 (1H, d, J = 3.8, H-3); 7.51 (1H, t, J = 7.8, H-4'); 7.51 (1H, d, J = 7.8, H-6'); 8.34
(1H, s, CH=N).
325

N-(2-Pyridylmethylidene)-2-trifluoromethylaniline (5a). Mass spectrum, m/z (Irel, %): 250 (2, M+),
249 (3, [M-H]+), 231 (2, [M-F]+), 223 (1, [M-CN]+), 222 (1, [M-HCN]+), 203 (7, [M-CN-F-H]+), 181 (100,
[M-CF3]+), 172 (5, [M-Py]+), 154 (6), 145 (25, [C6H4CF3]+), 125 (6), 105 (12, [M-C6H4CF3]+), 95 (10), 79 (19,
1
[PyH]+), 78 (14, Py+), 76 (9), 69 (5, [CF3]+), 52 (14), 51 (13). H NMR spectrum, , ppm (J, Hz): 7.12 (1H, d,
δ
J = 8.0, H-3'); 7.32 (1H, t, J = 8.0, H-5'); 7.39 (1H, ddd, J = 8.0, J = 4.8, J = 1.1, H-5); 7.57 (1H, t, J = 8.0, H-4');
7.69 (1H, d, J = 8.0, H-6'); 7.83 (1H, dt, J = 8.0, J = 1.4, H-4); 8.27 (1H, dt, J = 8.0, J = 1.1, H-3); 8.51 (1H, s,
CH=N); 8.70 (1H, m, J = 4.8, J = 1.4, J = 1.1, H-6).
N-(3-Pyridylmethylidene)-2-trifluoromethylaniline (5b). Mass spectrum, m/z (Irel, %): 251 (14,
[M+H]+), 250 (100, M+), 249 (96, [M-H]+), 231 (7, [M-F]+), 181 (5, [M-CF3]+), 172 (18, [M-Py]+), 152 (5), 145
(68, [C6H4CF3]+), 125 (13), 115 (5), 105 (9, [M-C6H4CF3]+), 95 (20), 79 (22, [PyH]+), 78 (10, Py+), 75 (17), 69
(6, [CF3]+), 63 (14), 51 (22). 1H NMR spectrum, , ppm (J, Hz): 7.06 (1H, d, J = 7.6, H-3'); 7.31 (1H, t, J = 7.6,
δ
H-5'); 7.43 (1H, dd, J = 8.0, J = 5.0, H-5); 7.56 (1H, t, J = 7.6, H-4'); 7.70 (1H, d, J = 7.6, H-6'); 8.33 (1H, dt,
J = 8.0, J = 2.0, H-4); 8.42 (1H, s, CH=N); 8.72 (1H, dd, J = 5.0, J = 2.0, H-6); 9.00 (1H, dd, J = 2.0, J = 0.8,
H-2).
N-(4-Pyridylmethylidene)-2-trifluoromethylaniline (5c). Mass spectrum, m/z (Irel, %): 251 (13,
[M+H]+), 250 (100, M+), 249 (68, [M-H]+), 231 (7, [M-F]+), 172 (47, [M-Py]+), 152 (5), 145 (86, [C6H4CF3]+),
125 (13), 105 (10, [M-C6H4CF3]+), 95 (21), 79 (43, [PyH]+), 78 (10, Py+), 75 (18), 69 (6, [CF3]+), 63 (10), 52
1
(16), 51 (29). H NMR spectrum, , ppm (J, Hz): 7.06 (1H, d, J = 7.8, H-3'); 7.33 (1H, t, J = 7.8, H-5'); 7.57
δ
(1H, t, J = 7.8, H-4'); 7.70 (1H, d, J = 7.8, H-6'); 7.77 (2H, dd, J = 4.2, J = 1.4, H-3, H-5); 8.38 (1H, s, CH=N);
8.78 (2H, dd, J = 4.2, J = 1.4, H-2, H-6).
N-[3-(2-Furyl)-2-propenylidene]-2-trifluoromethylaniline (6a). Mass spectrum, m/z (Irel, %): 266 (10,
[M+H]+), 265 (66, M+), 264 (35, [M-H]+), 246 (4, [M-F]+), 244 (5), 237 (30, [M-CO]+), 236 (100, [M-HCO]+),
224 (43), 216 (19), 211 (33), 196 (18), 172 (16, M-FurCHCH]+), 168 (59), 167 (44), 145 (70, [C6H4CF3]+), 125
(18), 95 (16), 75 (28), 69 (11, [CF3]+), 66 (29), 65 (41), 51 (32). H NMR spectrum, , ppm (J, Hz): 6.48 (1H,
1
δ
dd, J = 5.0, J = 2.0, H-4); 6.59 (1H, d, J = 5.0, H-3); 6.9-7.1 (3H, m, H-3', CH=CH); 7.28 (1H, t, J = 7.8, H-5');
7.45-7.55 (2H, m, H-5, H-4'); 7.64 (1H, d, J = 7.8, H-6'); 8.04 (1H, dd, J = 6.8, J = 0.6, CH=N).
N-[3-(5-Methyl-2-furyl)-2-propenylidene]-2-trifluoromethylaniline (6b). Mass spectrum, m/z
(Irel, %): 280 (9, [M+H]+), 279 (51, M+), 264 (35, [M-Me]+), 244 (12), 236 (42, [M-MeCO]+), 216 (33), 196
(13), 172 (10, [M-FurCHCH]+), 168 (17), 167 (55), 145 (45, [C6H4CF3]+), 125 (14), 107 (10), 95 (19), 77 (22),
69 (7, [CF3]+), 66 (11), 63 (13), 51 (21). H NMR spectrum, , ppm (J, Hz): 2.35 (3H, s, CH3); 6.08 (1H, d,
1
δ
J = 3.4, H-4); 6.48 (1H, d, J = 3.4, H-3); 6.8-7.0 (3H, m, H-3', CH=CH); 7.24 (1H, t, J = 8.8, H-5'); 7.50 (1H, t,
J = 8.8, H-4'); 7.63 (1H, d, J = 8.8, H-6'); 8.02 (1H, d, J = 8.0, CH=N).
N-[3-(5-Nitro-2-furyl)-2-propenylidene]-2-trifluoromethylaniline (6c). Mass spectrum, m/z (Irel, %):
310 (24, M+), 291 (5, [M-F]+), 265 (17), 264 (100, [M-NO2]+), 244 (10), 235 (11), 216 (28), 196 (22), 172 (15),
167 (69), 145 (62, [C6H4CF3]+), 125 (12), 107 (5), 95 (17), 75 (15), 69 (2, [CF3]+), 65 (14), 63 (21), 51 (20).
1H NMR spectrum, , ppm (J, Hz): 6.76 (1H, d, J = 3.8, H-3); 6.96 (1H, d, J = 16.0, α-CH); 6.97 (1H, d, J = 8.0,
δ
H-3'); 7.28 (1H, dd, J = 16.0, J = 8.6, -CH); 7.29 (1H, t, J = 8.0, H-5'); 7.36 (1H, d, J = 3.8, H-4); 7.54 (1H, t,
β
J = 8.0, H-4'); 7.66 (1H, d, J = 8.0, H-6'); 8.07 (1H, d, J = 8.6, CH=N).
The authors are grateful to the Latvian Committee for Science for financing the work (grant No. 181).
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