SIMILARITY AND DIFFERENCES IN THE REGIOSELECTIVITIES
1053
and 17a at a ratio of 1:1.25. By silica gel column
chromatography we isolated 115 mg (39%) of 16a and
148 mg (51%) of 17a. The physical constants and
spectral characteristics of 9a, 15b, and 16a coincided
with those reported in [8].
tography. Heating of 0.3 g (1 mmol) of 11 in 15 mL of
anhydrous THF containing H2SO4 at 65°C for 5 min
gave 0.22 g (74%) of 10a.
Acid-catalyzed rearrangement of 3H-pyrazoles
7d and 8e (general procedure). A solution of 1 mmol
of 3H-pyrazole 7d or 8e in 20 mL of acetic acid con-
taining a catalytic amount of concentrated sulfuric acid
was kept for 24 h at 20°C. The mixture was diluted
with 30 mL of water, and the precipitate was filtered
off, washed on a filter with 10 mL of a 5% aqueous
solution of NaHCO3 and with water until neutral
washings, and dried in air. Pyrazolones 23 and 25 were
isolated by crystallization.
Methyl 4-methyl-4,5-diphenyl-4H-pyrazole-3-
carboxylate (10a). Yield 80%, mp 104–105°C [5].
1H NMR spectrum, δ, ppm: 1.94 s (3H, CH3), 3.81 s
(3H, OCH3), 7.13–7.16 m (2H, Harom), 7.28–737 m
(5H, Harom), 7.43 t (1H, Harom, J = 7.5 Hz), 7.71 d (2H,
H
arom, J = 7.2 Hz). 13C NMR spectrum, δC, ppm: 19.2
(CH3), 52.8 (OCH3), 67.3 (C4), 126.0 (2C, Carom),
128.4 w (Carom), 128.6 (Carom), 128.9 (2C, Carom), 129.1
(2C, Carom), 129.6 (2C, Carom), 132.2 (Carom), 133.0 w
(Carom), 160.3 (C5), 172.4 (C=O), 182.2 (C3). Found,
%: C 73.91; H 5.50; N 9.51. C18H16N2O2. Calculated,
%: C 73.95; H 5.52; N 9.58.
Methyl 5-oxo-3,4-diphenyl-4,5-dihydro-1H-pyr-
azole-4-carboxylate (23). Yield 180 mg (90%), color-
less crystals, mp 125–126°C. IR spectrum, ν, cm–1:
3214 w, 1752 s, 1732 v.s, 1694 s, 1235 m, 1208 m,
1
Methyl 3-methyl-4,5-diphenyl-4H-pyrazole-4-
carboxylate (17a). mp 107–108°C. UV spectrum
(MeOH): λmax 286 nm (log ε 3.96). IR spectrum, ν,
cm–1: 3066 w, 2956 w, 1754 v.s., 1500 m, 1447 m,
1007 w, 779 w, 691 m. H NMR spectrum, δ, ppm:
3.74 s (3H, OMe), 7.31–7.42 m (8H, Harom), 7.71 d
(2H, Harom, J = 7.4 Hz), 9.78 br.s (1H, NH). 13C NMR
spectrum, δC, ppm: 53.9 (OMe), 66.2 (C4), 126.8 (2C,
Carom), 128.7 (2C, Carom), 128.9 (5C, Carom), 130.1 w
(Carom), 130.7 (Carom), 132.3 w (Carom), 156.5 (C5),
166.7 (C=O), 173.9 (C3). Found, %: C 69.30;
H 4.87; N 9.50. C17H14N2O3. Calculated, %: C 69.38;
H 4.79; N 9.52.
1
1436 m, 1378 s, 1228 s. H NMR spectrum, δ, ppm:
2.08 s (3H, Me), 3.75 s (3H, OMe), 7.31–7.89 m
(10H). 13C NMR spectrum, δС, ppm: 13.5 (Me), 53.7
(OMe), 79.2 (C4), 111.7 (Carom), 127.3 (2C, Сarom),
128.4 (2C, Carom), 128.9 (2C, Carom), 129.0 (Carom),
129.6 (2C, Carom), 130.2 w (Carom), 131.5 (Carom), 131.8
w (Carom), 166.4 (C=O), 173.3 (C3), 175.7 (C5). Found,
%: C 74.31; H 5.58; N 9.52. C18H16N2O2. Calculated,
%: C 73.95; H 5.52; N 9.58.
5-Oxo-3,4-diphenyl-4,5-dihydro-1H-pyrazole-
4-carbonitrile (25). Yield 148 mg (74%), light brown
crystals, mp 161–162°C. IR spectrum, ν, cm–1:
3210 m, 3113 m, 2245 w (CN), 1736 v.s, 1728 v.s,
1566 m, 1555 m, 1497 m, 1447 m, 1269 m, 768 m,
Methyl 4-methylidene-5,5-diphenyl-4,5-dihydro-
1H-pyrazole-3-carboxylate (11). A solution of 1 g
(3.4 mmol) of 3H-pyrazole 3a in 10 mL of anhydrous
THF containing 2 drops of concentrated sulfuric acid
was kept for 10 h at 20°C. The mixture was diluted
with 10 mL of water, and the product was isolated by
extraction with diethyl ether as described above. Yield
0.32 g (32%), colorless crystals, mp 154°C [14]. IR
spectrum, ν, cm–1: 3400 br.m (NH), 3068 w, 3030 w,
2955 m, 1718 v.s, 1525 m, 1450 s, 1400 m, 1240 s,
1100 s. 1H NMR spectrum, δ, ppm: 3.91 s (3H, OMe),
5.07 s and 6.39 s (1H each, =CH2), 7.02 br.s (1H, NH),
7.22–7.30 m (4H, Harom), 7.33–7.43 m (6H, Harom).
13C NMR spectrum, δC, ppm: 52.0 (OMe), 79.3 (C3),
112.9 (=CH2), 127.5 (4C, Carom), 127.9 (2C, Carom),
128.8 (4C, Carom), 136.8 w (C4), 143.7 (Carom), 146.7
(C5), 162.6 (C=O). Found, %: C 74.13; H 5.57; N 9.60.
C18H16N2O2. Calculated, %: C 73.95; H 5.52; N 9.58.
1
752 m, 721 m, 687 m, 644 m. H NMR spectrum, δ,
ppm: 7.34 t (2H, Harom, J = 7.4 Hz), 7.43 t (1H, Harom
J = 6.8 Hz), 7.45 br.s (5H, Harom), 7.69 d (2H, Harom
,
,
J = 7.8 Hz), 9.17 br.s (1H, NH). 13C NMR spectrum,
δC, ppm: 53.2 (C4), 113.6 (CN), 126.1 (2C, Carom),
126.8 (2C, Carom), 128.1 w (Carom), 129.2 (2C, Carom),
129.8 w (Carom), 130.1 (Carom), 130.3 (2C, Carom), 131.6
(Carom), 154.7 (C3), 170.0 (C=O). Found, %: C 75.48;
H 4.29; N 16.32. C16H11N3O. Calculated, %: C 73.55;
H 4.24; N 16.08.
REFERENCES
1. Van Alphen, J., Recl. Trav. Chim. Pays–Bas, 1943,
vol. 62, p.485.
2. Hüttel, R., Riedl, J., Martin, H., and Franke, K., Chem.
Ber., 1960, vol. 93, p. 1425.
Compound 11 was also formed in a small amount
from 3H-pyrazole 3a during silica gel column chroma-
3. Sammes, M.P. and Katritzky, A.R., Adv. Heterocycl.
Chem., 1983, vol. 34, p. 1.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 54 No. 7 2018