CERIUM(III) CHLORIDE HEPTAHYDRATE (CeCl3·7H2O)
1447
and the products contained two enaminone fragments
(see table, run nos. 2, 7, 11). Weakly activated anilines
were also converted into the corresponding enamin-
ones in good yields (run nos. 9, 5, 18). However,
anilines having strong electron-withdrawing groups
(e.g., p-nitroaniline) failed to react under the given
conditions even in 24 h.
N 8.4. C22H24N2O2. Calculated, %: C 75.63; H 6.94;
N 9.16.
3-(1-Phenylaminoethylidene)tetrahydrofuran-2-
one (run no. 17). Colorless crystals, mp 90–92°C. IR
spectrum (KBr), Ȟ, cm–1: 3250, 3030, 2900, 1674,
1
1634, 1247, 1019, 920. H NMR spectrum (200 MHz,
CDCl3), į, ppm: 10.1 br.s (1H, NH), 7.41–7 m (5H,
Ph), 4.42–4.3 t (2H, OCH2, J = 8.2 Hz), 3.07–2.89 t
(2H, =CCH2, J = 8.1 Hz), 2.1 s (3H, CH3). 13C NMR
spectrum (50 MHz, CDCl3), įC, ppm: 174.3, 153.9,
147.8, 139.6, 129.6, 125.3, 124.6, 89.7, 65.8, 26.9.
Found, %: C 70.5; H 6.5; N 7.0. C12H13NO2. Calculat-
ed, %: C 70.92; H 6.45; N 6.89.
The proposed procedure was successfully applied
to enamination of ȕ-diketones (run nos. 1–19) and
linear (run nos. 10–15) and cyclic ȕ-keto esters (run
nos. 16–21). It should be noted that in all cases the
attack by amine was directed exclusively at the acetyl
carbonyl group; no products which could result from
alternative attack were detected (run nos. 3, 6, 12).
3-[1-(2-Hydroxyethylamino)ethylidene]tetra-
hydrofuran-2-one (run no. 21). Colorless crystals,
mp 110–111°C. IR spectrum (KBr), Ȟ, cm–1: 3240,
Thus we have proposed an efficient procedure for
the synthesis of ȕ-enaminones in aqueous medium in
the presence of a catalytic amount of CeCl3·7H2O. It is
advantageous due to high yields of the target products,
high regioselectivity, mild reaction conditions, clear
reactions, and ecological safety.
1
2923, 1668, 1584, 1250, 1012, 955, 763. H NMR
spectrum (200 MHz, CDCl3), į, ppm: 8.32 br.s (1H,
NH), 4.33–4.22 t (2H, CH2, J = 8.7 Hz), 3.8–3.69 t
(2H, CH2, J = 5.8 Hz), 3.47–3.36 d.d (2H, CH2, J =
5.1, 5.2 Hz), 3.18 br.s (1H, OH), 2.9–2.8 t (2H, CH2,
J = 7.3 Hz), 2.1 s (3H, CH3). 13C NMR spectrum
(50 MHz, CDCl3), įC, ppm: 174.8, 158.4, 156.9, 85.2,
65.8, 62.1, 45.7, 26.9. Found, %: C 56.0; H 7.7; N 8.3.
C8H13NO3. Calculated, %: C 56.13; H 7.65; N 8.18.
EXPERIMENTAL
1
The H and 13C NMR spectra were recorded on
a Bruker Avance spectrometer operating at 200 MHz
1
for H. The IR spectra were measured on a Shimadzu
The authors are thankful to the Razi University
Research Council for partial support of this work.
470 spectrometer.
General procedure for enamination of ȕ-dicar-
bonyl compounds. A mixture of 1 mmol of ȕ-dicar-
bonyl compound, 1 mmol of amine, and 0.1 mmol of
CeCl3·7H2O in 5 ml of water was stirred at room tem-
perature for a time indicated in table. The progress of
reactions was monitored by GLC or TLC. When the
reaction was complete, the catalyst was separated by
filtration, the filtrate was extracted with methylene
chloride (3×10 ml), the extract was dried over magne-
sium sulfate, the solvent was removed, and the residue
was subjected to column or preparative thin-layer
chromatography on silica gel. The yields of enamin-
ones were 65 to 96%. Spectral parameters of some
enaminones are given below.
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N,N'-Bis(2-benzoyl-1-methylethenyl)-1,2-ethane-
diamine (run no. 7). Colorless crystals, mp 177–
179°C. IR spectrum (KBr), Ȟ, cm–1: 3360, 3120, 1525,
1
1512, 1080, 800, 748, 705. H NMR spectrum
(200 MHz, CDCl3), į, ppm: 11.6 s (1H, NH), 8.17–
7.1 m (5H, Ph), 5.7 s (1H, =CH), 3.82–3.3 m (2H,
CH2), 2.1 s (3H, CH3). 13C NMR spectrum (50 MHz,
CDCl3), įC, ppm: 188.7, 165.4, 140.5, 131.1, 128.7,
127.4, 93.4, 44.2, 19.7. Found, %: C 75.24; H 6.8:
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 41 No. 10 2005