Stereoselective synthesis and alkylation of N-methylmorpholinium 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-hydroxy- 5-(2-thenoyl)-6-trifluoromethyl- 1,4,5,6-tetrahydropyridine-2-thiolate. Molecular and crystal structure of 4,5-trans-4-(2-chlorophenyl)-3-cyano- 6-hydroxy-2-methallylthio-5-(2-thenoyl)- 6-trifluoromethyl-1,4,5,6-tetrahydropyridine

Article abstract of DOI:10.1023/A:1013889208646

The condensation of 2-chlorobenzaldehyde with cyanothioacetamide and 2-thenoyltrifluoroacetone in the presence of N-methylmorpholine takes place stereoselectively and leads to the formation of N-methylmorpholinium 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-hydroxy-5-(2-thenoyl) -6-trifluoromethyl-1,4,5,6-tetrahydropyridine-2-thiolate. The latter was used to synthesize the corresponding 2-alkylthiotetrahydropyridines. The structure of 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-hydroxy-2- methallylthio-5-(2-thenoyl)-6-trifluoromethyl-1,4,5,6-tetrahydropyridine was determined by X-ray crystallographic analysis.

Full text of DOI:10.1023/A:1013889208646

Chemistry of Heterocyclic Compounds, Vol. 37, No. 10, 2001
STEREOSELECTIVE SYNTHESIS AND
ALKYLATION OF N-METHYLMORPHOLINIUM
trans
4,5-
-4-(2-CHLOROPHENYL)-3-CYANO-6-HYDROXY-
5-(2-THENOYL)-6-TRIFLUOROMETHYL-
1,4,5,6-TETRAHYDROPYRIDINE-2-THIOLATE.
MOLECULAR AND CRYSTAL STRUCTURE OF
trans
4,5-
-4-(2-CHLOROPHENYL)-3-CYANO-
6-HYDROXY-2-METHALLYLTHIO-5-(2-THENOYL)-
6-TRIFLUOROMETHYL-1,4,5,6-TETRAHYDROPYRIDINE
S. G. Krivokolysko1, V. D. Dyachenko1, A. N. Chernega2, and V. P. Litvinov3
The condensation of 2-chlorobenzaldehyde with cyanothioacetamide and 2-thenoyltrifluoroacetone in
the presence of N-methylmorpholine takes place stereoselectively and leads to the formation of
N-methylmorpholinium 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-hydroxy-5-(2-thenoyl)-6-trifluoromethyl-
1,4,5,6-tetrahydropyridine-2-thiolate. The latter was used to synthesize the corresponding
2-alkylthiotetrahydropyridines. The structure of 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-hydroxy-2-
methallylthio-5-(2-thenoyl)-6-trifluoromethyl-1,4,5,6-tetrahydropyridine was determined by X-ray
crystallographic analysis.
Keywords: 2-thenoyltrifluoroacetone, tetrahydropyridines, 2-chlorobenzaldehyde, cyanothioacetamide,
alkylation, condensation.
The reaction of benzoyltrifluoroacetone with 2-thienylmethylenecyanoselenoacetamide was used
successfully for the synthesis of 3,4-trans-5-benzoyl-3-cyano-4-(2-thenoyl)-6-trifluoromethyl-3,4-
dihydropyridine-2(1H)-selenone [1]. At the same time partially hydrogenated sulfur-containing pyridines with a
trifluoromethyl group are unknown [2].
We established that the reaction of 2-chlorobenzaldehyde (1), cyanothioacetamide (2), and
2-thenoyltrifluoroacetone (3) in ethanol (~20°C) in the presence of N-methylmorpholine takes place
stereoselectively with the formation of N-methylmorpholinium 4,5-trans-4-(2-chlorophenyl)-3-cyano-6-
__________________________________________________________________________________________
1
Taras Shevchenko Lugansk State Pedagogical University, Lugansk 91011, Ukraine; e-mail:
2
kgb@lgpi.lugansk.ua. Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kiev.
3 N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow; e-mail:
vpl@cacr.ioc.ac.ru. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1324-1331, October,
2001. Original article submitted May 18, 1999. Revision submitted January 7, 2000.
1208
0009-3122/01/3710-1208$25.00©2001 Plenum Publishing Corporation

hydroxy-5-(2-thenoyl)-6-trifluoromethyl-1,4,5,6-tetrahydropyridine-2-thiolate (4). It is clear that the
regioselectivity of the reaction is determined in the intermediate 5. During the alkylation of the salt 4 by the
halides 6 the corresponding sulfides 7 were obtained.
The structure of compounds 4, 7 was confirmed by the results of elemental analysis and by
1
physicochemical methods (Experimental, Tables 1 and 2). Thus, the H NMR spectra of these compounds
contain the signals for the protons of all the substituents, the NH group, and the N-methylmorpholinium cation.
The signals of the 4-H and 5-H protons are represented by broad doublets in the regions of 4.80-4.92 and
3
3.93-4.40 ppm with spin–spin coupling constant J = 10-14 Hz and also by a broad signal in the region of
4.30-4.43 ppm.
Me
O
O
Cl
N
CN
CN
O
+
Cl
+
S
S
_
S
+
S
NH2
F3C
3
O
F3C
Me
O N
H
2
NH
CHO
5
1
O
Cl
CN
O
O
Cl
CN
HalCH2R
6a–i
Me
NH
_
S
S
+
N
H
4
S
HO
HO
N
H
3 7a–h
S
R
CF3
CF
O
6, 7 a Hal = I, R = H; b Hal = I, R = Me; c Hal = Cl, R = COOMe; d Hal = Cl, R = COOEt;
e Hal = Cl, R = C(Me)=CH2; f Hal = Cl, R = Ph; g Hal = Cl, R = CONH2; h Hal = Cl,
R = 4-BrC6H4NHCO; i Hal = Br, R = COPh
The integral intensity ratio of the above-mentioned doublets and of the broad signal is ~2:1. The
presented data indicate that compounds 4 and 7 represent a mixture of conformers (A and B), in which the
conformer A with the trans-diaxial arrangement of the 4-H and 5-H protons predominates.
In order to explain the 1H NMR data and to establish unambiguously the structure of the
tetrahydropyridines 4 and 7 an X-ray crystallographic analysis of compound 7e was undertaken (Fig. 1, Table 3;
1
the numbering of the atoms in the names and in the H NMR spectra presented in Table 1 does not conform to
IUPAC nomenclature).
The central heterocycle N(1)C(1-5) is nonplanar (the deviations of the atoms from the mean-square plane
are 0.07-0.31 Å) and has a half-chair conformation; the N(1)C(1-3) atoms are coplanar within 0.001 Å, while the
C(4) and C(5) atoms project from this plane by -0.47 and 0.23 Å. The torsion angles in this heterocycle
N(1)C(1)C(2)C(3) 0.3, C(1)C(2)C(3)C(4) 18.6, C(2)C(3)C(4)C(5) -45.6, C(3)C(4)C(5)N(1) 55.8, C(4)C(5)N(1)C(1) -38.6,
C(5)N(1)C(1)C(2) 10.5° are close to those found in cyclohexene and its derivatives [3].
1209

TABLE 1. The 1H NMR Spectra of the Synthesized Compounds 7a-i
Com-
Chemical shifts, δ, ppm, SSCC (J), Hz*
pound
2.52 (s, SMe); 4,25 (br. d, 3J = 11.4, 5-НA); 4.35 (br. s, 4-НB and 5-HB);
4.88 (br. d, 3J = 11.4, 4-НА); 7.15 and 7.87 (two m, Ar and Het); 7.43 (s, ОН);
8.20 (s, NH)
7a
7b
7c
7d
7e
7f
1.28 (t, 3J = 6.5, Mе); 3.01 and 3.07 (two d, 3J = 6.5, SCH2); 4.20 (br. d, 3J = 14.0, 5-НА);
4.33 (br. s, 4-НB and 5-НB); 4.89 (br. d, 3J = 14.0, 4-НА); 7.15 and 7.87 (two m,
Ar and Het); 7.42 (s, OH); 8.27 (s, NH)
3.73 (s, Mе); 4.00 (s, SCH2); 4.22 (br. d, 3J = 11.8, 5-НА); 4.41 (br. s, 4-НB and 5-НB);
4.85 (br. d, 3J = 11.8, 4-НА); 7.16 and 7.90 (two m, Ar and Het); 7.51 (s, OH);
8.31 (s, NH)
1.25 (t, 3J = 6.6, Mе); 3.99 (s, SCH2); 4.18 (q, 3J = 6.6, ОСН2); 4.30 (br. d,
3J = 13.0, 5-НА); 4.33 (br. s, 4-НB and 5-НB); 4.87 (br. d, 3J = 13.0, 4-НА);
7.13, 7.71 and 7.89 (three m, Ar and Het); 7.50 (s, ОН); 8.31 (s, NH)
1.85 (s, Mе); 3.62 and 3.72 (two d, 2J = 8.0, SCH2); 4.16 (br. d, 3J = 12.0, 5-НА);
4.43 (br. s, 4-НB and 5-НB); 4.86 (br. d, 3J = 12.0, 4-НА); 4.98 (s, =СН2); 7.15 m,
7.65 m and 7.88 d, 3J = 4.8 (Ar and Het); 7.42 (s, OH); 8.24 (s, NH)
3.93 (br. d, 3J = 11.7, 5-НA); 4.26 and 4.34 (two d, 2J = 12.8, SCH2);
4.38 (br. s, 4-HB and 5-HB); 4.80 (br. d, 3J = 11.7, 4-НА); 7.13 m, 7.41 m,
7.75 m and 7.88 d, 3J = 4.7 (Ar and Het); 7.49 (s, ОН); 8.42 (s, NH)
3.63 and 3.73 (two d, 2J = 15.4, SCH2); 4.38 (br. d, 3J = 12.5, 5-НА);
7g
7h
4.42 (br. s, 4-НB and 5-НB); 4.87 br. d, 3J = 12.5, 4-НА); 7.12 m and 7.87 d,
3J = 4.9 (Ar and Het); 7.46 (s, ОН); 7.74 and 8.05 (two br. s, CONH2); 10.04 (s, NH)
3.91 and 3.97 (two d, 2J = 15.5, SCH2); 4.40 (br. d, 3J = 12.0, 5-НА);
4.43 (br. s, 4-НB and 5-НB); 4.90 (br. d, 3J = 12.0, 4-НА); 7.13 m,
7.58 br. s and 7.89 m (Ar, Het and ОН); 9.19 (s, NH); 10.69 (s, CONH)
4.32 (br. d, 3J = 10.0, 5-НA); 4.36 (br. s, 4-НB and 5-НB); 4.81 (s, SCH2);
7i
4.92 (br. d, 3J = 10.0, 4–НА); 7.16, 7.66 and 7.95 (three m, Ar, Het and OH); 8.33 (s, NH)
_______
* The integral intensity of the protons of compounds 7 corresponds to the
proposed formulas and to the ratio of the conformers A and B.
Fig. 1. General view of the molecule of compound 7e with the numbering of the atoms.
Of the hydrogen atoms only H(1) and H(2) are shown.
1210

TABLE 2. The Characteristics of the Synthesized Compounds 7a-i
Found, %
——————
Calculated, %
IR spectrum,
Com-
pound
Empirical
formula
Yield,
%
mp, °С
ν, cm-1
C
H
N
S
C19H14ClF3N2O2S2
C20H16ClF3N2O2S2
49.93
49.73
3.25
3.08
5.77
6.10
13.71 215-217 3250-3390
78
75
7a
7b
13.97
(NH, OH),
2200 (CN),
1635 (CO)
50.56
50.76
3.68
3.41
5.71
5.92
13.74 179-181 3150-3330
13.56
(NH, OH),
2205 (CN),
1635, 1655
(CO)
C21H16ClF3N2O4S2
C22H18ClF3N2O4S2
C22H18ClF3N2O2S2
С25H18ClF3N2O2S2
48.95
48.79
3.33
3.12
5.11
5.42
12.68 163-165 3210-3375
67
81
83
67
7c
7d
7e
7f
12.41
(NH, OH),
2205 (CN),
1620, 1660,
1736 (CO)
49.99
49.77
3.13
3.42
5.44
5.28
11.78 104-106 3180-3360
12.08
(NH, OH),
2195 (CN),
1635, 1665,
1740 (CO)
52.73
52.96
3.85
3.64
5.78
5.61
12.62 164-166 3210-3330
12.85
(NH, OH),
2202 (CN),
1630, 1675
(CO)
56.33
56.13
3.52
3.36
5.42
5.24
11.71 188-190 3240, 3390
11.99
(NH, OH),
2195 (CN),
1620, 1680
(CO)
C20H15ClF3N3O3S2
47.97
47.86
3.23
3.01
8.47
8.37
12.53 239-241 3120-3360
88
93
77
7g
7h
7i
12.78
(NH, OH),
2204 (CN),
1620, 1650,
1702 (CO)
C26H18BrClF3N3O3S2 47.82
47.54
2.92
2.76
6.19
6.40
9.81
9.76
243-245 3210-3300
(NH, OH),
2190 (CN),
1650, 1690
(CO)
C26H18ClF3N2O3S2
55.72
55.47
3.29
3.22
5.21
4.98
11.53 124-126 3240, 3390
11.39
(NH, OH),
2195 (CN),
1620, 1680
(CO)
We note that in related compounds [4] the central N(1)C(1-5) ring is appreciable flatter on account of
n(N(1))–π*(C(5)=O) conjugation. The "torsion angle" (the pseudotorsion angle between the C(1)–C(2) and C(4)–C(5)
ψ
bonds [3]) amounts to 27.2°. As a result of conjugation between the unshared electron pair of the N(1) atom and
the system of the C(1)=C(2) bond the interatomic N(1)–C(1) separation of 1.361(9) Å is substantially shortened
π
compared with the range of 1.43-1.45 Å characteristic of ordinary N(sp2)–C(sp2) bonds [5, 6]. The hydrogen
atoms H(3) and H(4) are trans-diaxial (torsion angle H(3)C(3)C(4)H(4) -170.8°). The values of the torsion angle
C(7)C(3)C(4)C(13) 65 and 78°, the bond lengths Cl(1A)–C(8) 1.638(7) and Cl(1B)–C(12) 1.455(9) Å, and the bond angles
Cl(1A)–C(8)–C(7) 122.4(6) and Cl(1B)–C(12)–C(7) 129.2(7)°, Cl(1A)–C(8)–C(9) 115.8(6) and Cl(1B)–C(12)–C(11) 106.3(7)°
confirm the existence of two conformational isomers A and B for the investigated compound, formed as a result
1211

) and Bond Angles (ω) in the Molecule of
TABLE 3. The Bond Lengths (d
Compound 7e
Bond
d, Å
Angle
ω, deg
S(1)–C(1)
1.753(7)
1.815(9)
1.714(7)
1.662(11)
1.361(9)
1.436(9)
1.343(9)
1.521(9)
1.55(1)
C(1)–S(1)–C(19)
C(14)–S(2)–C(17)
C(1)–N(1)–C(5)
N(1)–C(1)–C(2)
C(1)–C(2)–C(3)
C(2)–C(3)–C(4)
C(3)–C(4)–C(5)
N(1)–C(5)–C(4)
N(2)–C(6)–C(2)
S(2)–C(14)–C(15)
C(14)–C(15)–C(16)
C(15)–C(16)–C(17)
S(2)–C(17)–C(16)
100.7(4)
91.3(5)
S(1)–C(19)
S(2)–C(14)
S(2)–C(17)
N(1)–C(1)
N(1)–C(5)
C(1)–C(2)
C(2)–C(3)
C(3)–C(4)
C(4)–C(5)
C(14)–C(15)
C(15)–C(16)
C(16)–C(17)
121.5(6)
121.9(6)
122.7(6)
109.3(5)
110.9(6)
109.6(6)
177.1(8)
111.9(6)
110.3(8)
112.3(9)
114.2(7)
1.53(1)
1.383(11)
1.422(12)
1.345(14)
of the initial rotation of the benzene ring about the ordinary C(3)–C(7) bond. The benzene ring C(7-12) in the
molecule of 7e is rotated by 73.2° in relation to the mean-square plane of the N(1)C(1-5) ring, and the S(2)O(2)C(13-17)
and S(1)C(1)C(19) groups form dihedral angles of 85.2 and 58.6° with the central heterocycle. In turn, the C(19-21)
bond system is rotated significantly in relation to the S(1)C(1)C(19) group. (The corresponding dihedral angle
amounts to 77.3°.) The bond lengths S(1)–C(1) 1.753(7) and S(1)–C(13) 1.815(9) Å and the bond angle C(1)–S(1)–C(13)
100.7(4)° are close to the corresponding values found in the molecules of known tetrahydropyridines [4]. A
particular feature of the structure of compound 7e is the fairly strong [7] intramolecular hydrogen bond
O(1)–H(2)···O(2), which closes the six-membered ring C(4)C(5)O(1)H(2)O(2)C(13). The geometric parameters of this
bond are as follows: O(1)···O(2) 2.668(9), O(1)–H(2) 1.08(12), O(2)···H(2) 1.85(12) Å, O(1)H(2)···O(2) 130(6)°. (The
statistical mean value of the O···O distance for hydrogen bonds of the O–H···O type is 2.72 [8].) In the crystal
the molecules of compound 7e are linked into infinite chains by means of relatively weak N(1)–H(1)···N(2)
hydrogen bonds (Fig. 2).
Fig. 2. A bc projection of the crystal structure of 7e. (The dotted lines represent the hydrogen bonds.)
1212

TABLE 4. The Coordinates of the Atoms and the Equivalent Isotropic
Temperature Factors (Ueq) in the Structure of 7e
Atom
*
x
y
z
Ueq, Å2
Cl(1A)
Cl(1B)
S(1)
0.8697(3)
0.6238(8)
0.43073(14)
1.09186(17)
0.7779(5)
0.9035(4)
0.7660(4)
0.7722(5)
0.9340(4)
0.6335(5)
0.4729(6)
0.5661(5)
0.6012(5)
0.7181(5)
0.7809(5)
0.7458(6)
0.5281(6)
0.7417(5)
0.8107(6)
0.8373(7)
0.7892(9)
0.7193(9)
0.6988(6)
0.8984(6)
0.9644(5)
0.9420(6)
1.0325(9)
1.1151(8)
0.7975(7)
0.4235(7)
0.4535(7)
0.546(1)
0.6176(2)
0.4422(7)
0.30844(15)
0.42822(19)
0.1584(4)
0.1841(4)
0.1078(3)
0.2889(4)
0.3890(5)
0.2597(5)
0.5657(5)
0.3348(5)
0.4237(5)
0.4476(5)
0.3553(5)
0.2733(5)
0.5011(6)
0.5222(5)
0.5961(6)
0.6566(6)
0.6428(7)
0.5709(7)
0.5127(5)
0.3792(5)
0.3900(5)
0.3741(6)
0.3935(8)
0.4238(7)
0.1801(6)
0.2595(7)
0.3277(7)
0.322(1)
0.3717(3)
0.0406(7)
0.23798(16)
0.3163(2)
0.2213(5)
0.3654(5)
0.3744(5)
0.4559(4)
0.4285(5)
0.2999(5)
0.2201(7)
0.2704(5)
0.2641(5)
0.2889(5)
0.2829(5)
0.3431(6)
0.2399(6)
0.2098(5)
0.2434(6)
0.1701(9)
0.0631(9)
0.0265(6)
0.1009(6)
0.3292(7)
0.2599(7)
0.1496(7)
0.1149(9)
0.197(1)
0.0898
0.0988
0.0590
0.0823
0.0884
0.0862
0.0943
0.0671
0.0740
0.0522
0.0739
0.0436
0.0431
0.0439
0.0443
0.0523
0.0546
0.0531
0.0834
0.0927
0.1196
0.1115
0.0991
0.0547
0.0527
0.0663
0.0914
0.0890
0.0656
0.0775
0.0711
0.1089
0.1119
0.09(3)
0.13(4)
S(2)
F(1)
F(2)
F(3)
O(1)
O(2)
N(1)
N(2)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
H(1)
H(2)
0.3237(8)
0.3659(8)
0.4562(7)
0.5310(9)
0.460(1)
0.306(7)
0.49(1)
0.3781(9)
0.605(7)
0.846(9)
0.403(1)
0.200(7)
0.326(8)
_______
* The Cl(1) atom is randomized between the two positions A and B with
occupations 0.72 and 0.28 respectively.
The principal geometric parameters of these H bonds are as follows: N(1)–H(1) 0.93(9), N(1)···N(2)
3.043(9), N(2)···H(1) 2.13(9) Å, N(1)H(1)···O(1) 167(6)°. (The typical value of the N···N distance for H bonds of the
N–H···N type is 2.98 Å [8].)
EXPERIMENTAL
The IR spectra were recorded in vaseline oil on an IKS-29 spectrophotometer. The NMR spectra were
recorded on a Bruker AM-300 instrument (300 MHz) (for compounds 7a-c,h,i) and a Bruker WP-100 SY
instrument (100 MHz) (for compounds 4, 7d-g) in DMSO-d6 with TMS as internal standard. The reaction and
the individuality of the products were monitored by TLC on Silufol UV-254 plates (eluent 3:5 acetone–hexane).
1213

trans
-4-(2-Chlorophenyl)-3-cyano-6-hydroxy-5-(2-thenoyl)-6-
N-Methylmorpholinium
4,5-
trifluoromethyl-1,4,5,6-tetrahydropyridine-2-thiolate (4). To a mixture of 2-chlorobenzaldehyde 1 (2.25 ml,
20 mmol) and three drops of N-methylmorpholine in ethanol (30 ml) at 20°C while stirring we added
successively cyanothioacetamide 2 (2 g, 20 mmol), after 5 min 2-thenoyltrifluoroacetone 3 (4.44 g, 20 mmol),
and a further portion of N-methylmorpholine (2.52 ml, 25 mmol). After 2 h the precipitate was filtered off and
washed with acetone. We obtained 9.94 g (91%) of the salt 4; mp 168-170°C. IR spectrum, cm-1: 3195,
H NMR spectrum, δ, ppm,
3330-3420 (N+H, NH, OH), 2175 (CN), 1620 (CO). 1
J (Hz): 2.69 (3H, s, NMe); 3.03
3
(4H, m, CH2NCH2); 3.76 (4H, m, CH2OCH2); 4.20 (2/3H, br. d, J = 12.2, 5-HA); 4.50 (2/3H, br. s, 4-HB and
5-HB); 4.81 (2/3H, br. d, 3J = 12.2, 4-HA); 7.10, 7.67, and 7.89 (9H, three m, Ar, Het, OH, and NH). (The signal
of N+H does not appear on account of deuteroexchange.) Found, %: C 50.82; H 4.11; N 7.94; S 11.92.
C23H23ClF3N3O3S2. Calculated, %: C 50.59; H 4.25; N 7.70; S 11.74.
trans
4,5-
-4-(2-Chlorophenyl)-3-cyano-6-hydroxy-2-R-methylthio-5-(2-thenoyl)-6-trifluoromethyl-
1,4,5,6-tetrahydropyridines (7a-i). To a suspension of the salt 4 (2.73 g, 5 mmol) in 80% ethanol (30 ml)
while stirring we added a 10% solution of potassium hydroxide (2.8 ml, 5 mmol) and after 5 min the
corresponding halide 6 (5 mmol). After 3 h the precipitate was filtered off and washed with ethanol and hexane.
The characteristics of compounds 7 are given in Tables 1 and 2.
X-ray Crystallographic Analysis of a Single Crystal of Compound 7e. A single crystal
(0.21×0.33×0.38 mm) was investigated at 18°C on an Enraf-Nonius CAD-4 automatic four-circle diffractometer
(CuK radiation, ratio of scan rates /2 = 1.2,
ω θ
= 60°, segment of sphere 0
h
14, 0
k
15,
≤
α
θmax
≤
≤
≤
-14
l
14). In all 3741 reflections were collected, of which 3406 were symmetrically independent. The
≤ ≤
crystals of compound 7e are monoclinic, a = 13.218(2), b = 14.047(5), c = 12.894(7) Å,
= 107.10(3)°,
β
V = 2288.2 Å3, M = 498.97, Z = 4, dcalc = 1.45 g/cm3, = 35.97 cm-1, space group P21/c. The structure was
µ
interpreted by the direct method and refined by least-squares treatment in full-matrix anisotropic approximation
using the CRYSTALS software [9]. In the refinement 2195 reflections with I > 4(I) were used (306 refined
parameters, number of reflections per parameter 7.2). The positions of most of the hydrogen atoms were
calculated by geometry, and these atoms were included in the calculation with fixed position and temperature
parameters. Only the H(1) and H(2) atoms, attached to the N(1) and O(1) atoms respectively, were revealed
objectively from the difference synthesis and refined isotropically. Allowance for absorption in the crystal was
made by an azimuthal scan [10]. The Chebyshev weighting scheme with parameters 2.50, -1.79, 1.07, and -1.30
was used during refinement. The final values of the convergence factors were R = 0.076 and Rw = 0.085,
GOF = 1.079. The atomic coordinates are given in Table 4.
The work was carried out with financial support from the Russian Fundamental Research Fund (project
No. 99-03-32965).
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