J. CHEM. RESEARCH (S), 1998 443
3,3-Dimethyl-1-(4-iodophenyl)urea 1f.ÐMp 186±187 8C; ꢀH
[(CD3)2SO] 2.98 (6 H, s), 7.43 (4 H, t) (Found: C, 37.39; H, 3.98;
N, 9.55. C9H11IN2O. requires C, 37.26; H, 3.88; N, 9.66%).
1-(4-Acetylphenyl)-3,3-dimethylurea 1g.ÐMp 137±138 8C; ꢀH
[(CD3)2SO] 2.50 (3 H, s), 2.99 (6 H, s), 7.77 (4 H, t) (Found:
C, 64.17; H, 6.76; N, 13.79. C11H14N2O2. requires C, 64.06; H, 6.82;
N, 13.68%).
By the method described herein (see also Experimental),
fourteen 1-aryl-3,3-dialkylureas (1a±k, 2a±c) were syn-
thesized and relevant data are shown in Table 1, where f
and g are reported for the ®rst time.
In summary, we present
a convenient method for
the preparation of 1-aryl-3,3-dialkylureas. The most
advantageous features of the synthetic procedure are: (i) the
starting materials are readily available and less toxic,
(ii) the reaction is rapid and the reaction conditions are
mild, (iii) the reaction is very clean and the product work-
up is very easy, and (iv) the product yield is usually very
high. Using this method, preparation of variously sub-
stituted 1-aryl-3,3-dialkylureas are expected to be no longer
a challenging obstacle in ordinary laboratories.
This work was supported by the Natural Science
Foundation of China (NSFC) and the State Education
Commission of China (SECC) to whom the authors wish to
express their sincere gratitude. We also thank a referee for
his valuable suggestion regarding revision to the manuscript.
Received, 16th March 1998; Accepted, 29th April 1998
Paper E/8/02088D
Experimental
References
Mps (uncorrected) were measured on a Yanaco apparatus; 1H
NMR spectra were recorded on a JEOL-90Q NMR spectrometer,
using Me4Si as internal standard; elemental analyses were performed
on a PE-240 elementary analyzer. Common reagents, anilines and
dialkylamines were commercial products. Triphosgene was prepared
according to the literature method.6 Ethyl acetate was dried and
distilled from P2O5 before use.
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General Procedure for the Preparation of Compounds 1 and 2
[Taking 3,3-Dimethyl-1-(4-tolyl)urea 1b as an Example].ÐTo
a
solution containing 0.6 g (2 mmol) triphosgene dissolved in 20 ml
dry ethyl acetate was added 0.6 g (5.6 mmol) p-toluidine (dissolved
in 15 ml dry ethyl acetate) dropwise under stirring at room tempera-
ture. The mixture was warmed to dissolve the precipitates and was
kept re¯uxing for an additional 15 min. After cooling to room tem-
perature, the solution mixture was rota-evaporated, then 30 ml
anhydrous ether was added and the insolubles were ®ltered o.
To the ®ltrate was added dropwise a 30% aqueous dimethylamine
solution (containing 1.0 g amine) with stirring at 0±5 8C. The result-
ing crystals were ®ltered o and were washed with cold water
and ether consecutively. Recrystallization from ethyl acetate±light
petroleum (bp. 30±60 8C) gave colorless needles, yield 95%.
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894 [note: this compound was synthesized in our laboratory
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7 (a) A. L. Chimishkyan, L. P. Svetlova, T. V. Leonova and N. D.
Gulyaev, Zh. Obshch. Khim., 1984, 54, 1477; (b) US Pat.,
2 655 445, 1953, C. W. Todd (to E. Idu Pout de Newours & Co);
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