TOKMADZHYAN
1748
1
corresponding acid, and at the predominant presence of
the imidol form a retrobeckmann rearrangement occurs
with the formation of the initial oxime. Apparently in
the case of the products of Beckmann rearrangement of
methyl ketone oximes of unsaturated γ-lactone, aromatic
and alicyclic series the acid amides in the mixture АсOH–
HCl exist prevailingly in the imidol form which results
in the formation of the initial oximes.
1690 (C=O), 1625 (C=C). Н NMR spectrum, δ, ppm:
1.0–2.0 m [10Н, (СН2)5], 2.27 s (4-СН3), 2.45 s (СН3NH),
6.60 br.s (NH).
N-Methylbenzamide (Ic). Yield 1.68 g (83%), mp
114–115°С [9], Rf 0.63. IR spectrum, ν, cm–1: 3350 (NH),
1690 (C=O), 1600–1500 (C=Carom). Н NMR spectrum,
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δ, ppm: 2.47 d (СН3NH, J 4.9 Hz), 7.06–7.14 m (5Нarom),
9.60 br.s (NH).,
p-Hydroxybenzoic acid N-methylamide (Id). Yield
2.15 g (95%), mp 123–125°С, Rf 0.65. IR spectrum, ν,
cm–1: 3580 (ОН), 3370 (NH), 1690 (C=O), 1600–1500
(C=Carom). 1Н NMR spectrum, δ, ppm: 2.48 d (СН3NH,
EXPERIMENTAL
IR spectra of compounds synthesized were recorded
on a spectrophotometer Specord 75 IR from mulls in
mineral oil, 1Н NMR spectra, on a spectrometer Varian
Mercury-300 (300 MHz), internal reference TMS. Mass
spectrum of an electron impact (direct sample admission)
was obtained on an instrument M-1321 А at the energy
of ionizing electrons 50–70 eV. The purity of compounds
synthesized was checked by TLC on Silufol UV-254
plates, eluent acetone–benzene, 1:2, development in
iodine vapor and under UV irradiation.
J 4.9 Hz), 6.61 d (2Нarom, J 8.0 Hz), 6.89 d (2Нarom
J 8.0 Hz), 9.40 s (1Н, ОН), 9.58 br.s (1Н, NH).
,
N-Methylcyclohexylamide (Ie). Yield 0.3 g (67%),
mp 140°С [8], Rf 0.60. IR spectrum, ν, cm–1: 3370 (NH),
1690 (C=O). 1Н NMR spectrum, δ, ppm: 0.7–0.95 m
(6Н, С3Н2, С4Н2, С5Н2), 1.27 and 1.39 d.d (2Н, Н2а,6а
,
J 8.1, J 4.9 Hz), 1.49 and 1.52 d.d (2Н, Н2b,6b, J 5.4,
J 5.4 Hz), 2.47–2.83 m (1Н, Н1), 3.01 d (СН3NH,
J 4.9 Hz), 9.58 br.s (1Н, NH).
Oximes Ia–Ic, Ie were synthesized by known methods
Hydrolysis of N-methylamides in sulfuric acid.
Amixture of 3 mmol of N-methylamide IIа–IIe and 10 ml
of 20% Н2SO4 was heated over 10 h at 75°С, evaporated
at a reduced pressure, and the residue was recrystallized.
[2, 8, 14].
Methyl p-hydroxyphenyl ketone oxime (Id). To a so-
lution in alcohol of 1.36 g (0.01 mol) of the ketone was
added 0.7 g (0.01 mol) of hydroxylamine hydrochloride
and 0.7 g (0.005 mol) of potassium carbonate as a satu-
rated water solution. The mixture was stirred at room
temperature for 1 h, the precipitate was filtered off, the
filtrate was evaporated at a reduced pressure. Yield 1.26 g
(83%), mp 143°С (from ethanol). IR spectrum, ν, cm–1:
4,5,5-Trimethyl-2-oxo-2,5-dihydrofuran-3-carbox-
ylic acid (IIIa). Yield 0.45 g (88%), mp 113°С (from
xylene) [5].
4-Methyl-2-oxo-5,5-pentamethylene-2,5-
dihydrofuran-3-carboxylic acid (IIIb). Yield 0.48 g
(76%), mp 144°С (from heptane) [6].
1
3580 (ОН), 1630 (C=N conjug.), 1600 (arom). Н NMR
spectrum, δ, ppm: 2.3 s (3Н, СН3–С=N), 6.8–7.7 m
(4Нarom), 9.8 s (1Н, ОН), 10.2 s (1Н, ОН).
Benzoic acid (IIIc). Yield 0.195 g (80%), mp 121°С
(from water) [10].
p-Hydroxybenzoic acid (IIId). Yield 0.215 g (78%),
mp 216–217°С (from methanol) [11].
N-Methylamides IIa–IIe. A mixture of 1.5 mmol of
oxime, 5 ml of anhydrous ether, and 5 ml of boron tri-
fluoride etherate was stirred for 1 h at room temperature.
The precipitated crystals were filtered off.
Cyclohexanecarboxylic acid (IIIe). Yield 0.15 g
(55%), mp 235–238°С (from ethanol) [15].
No depression of the melting point was observed in
mixed samples of compounds IIIа–IIIe with the cor-
responding acids prepared by known methods [5, 6, 10,
11, 15].
4,5,5-Trimethyl-2-oxo-2,5-dihydrofuran-3-car-
boxylic acid N-methylamide (Ia). Yield 0.25 g (93%),
white crystals, mp 65–66°С [2], Rf 0.60. IR spectrum, ν,
cm–1: 3370 (NH), 1755 (C=O), 1685 (C=O), 1630 (C=C).
1Н NMR spectrum, δ, ppm: 1.44 s (6H, 5,5-СН3), 2.28 s
(4-СН3), 2.40 d (СН3NH, J 4.9 Hz), 7.50 br.s (NH).
Hydrolysis of N-methylamides IIa–IIe in the
presence of acetic and hydrochloric acids. A mixture
of 3 mmol of N-methylamide IIа–IIe, 15 ml of 80%
АсОН, and 1.5 ml of concn. НСl was heated for 10 h
at 75°С, evaporated at a reduced pressure, treated with
75 ml of cold 10% solution of NH4OH, and excess water
4-Methyl-2-oxo-5,5-pentamethylene-2,5-dihydro-
furan-3-carboxylic acid N-methylamide (Ib). Yield
0.25 g (76%), white crystals, mp 104–105°С [2], Rf
0.68. IR spectrum, ν, cm–1: 3365 (NH), 1755 (C=O),
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 11 2011