K. Ananda Kumar et al. / Tetrahedron Letters 42 (2001) 7873–7875
7875
dure is convenient, involves simple experimental proce-
dure and product isolation; hence, it is a useful addition
to the existing methods.
2. (a) Atwal, K. S.; Rovnyak, G. C.; O’Reilly, B. C.;
Schwartz, J. J. Org. Chem. 1989, 54, 5898; (b) Atwal,
K. S.; Swanson, B. N.; Unger, S. E.; Floyd, D. M.;
Moreland, S.; Hedberg, A.; O’Reilly, B. C. J. Med.
Chem. 1991, 34, 806; (c) Rovnyak, G. C.; Atwal, K. S.;
Hedberg, A.; Kimball, S. D.; Moreland, S.; Gougoutoy,
J. Z.; O’Reilly, B. C.; Schwartz, J.; Malley, M. F. J.
Med. Chem. 1992, 35, 3254; (d) Kappe, C. O.; Fabian,
W. M. F. Tetrahedron 1997, 53, 2803.
1. Experimental
Melting points were determined using a Mel-Temp.
apparatus in open capillary tubes and were uncorrected.
The IR spectra were obtained on a Perkin–Elmer Spec-
3
. (a) Snider, B. B.; Shi, Z. J. Org. Chem. 1993, 58, 3828
and references cited therein; (b) Overman, L. E.;
Rabinowitz, M. H.; Renhowe, P. A. J. Am. Chem. Soc.
1
trum instrument at 1000 units. H NMR spectra were
recorded on a Varian Gemini 2000 MHz spectrometer
using TMS as an internal standard in DMSO-d6.
1995, 117, 2657 and references cited therein.
4
. (a) Patil, A. D.; Kumar, N. V.; Kokke, W. C.; Bean,
M. F.; Freyer, A. J.; DeBrosse, C.; Mai, S.; Truneh,
A.; Faulkner, D. J.; Carte, B.; Breen, A. L.; Hertzberg,
R. P.; Johnson, R. K.; Westley, J. W.; Potts, B. C. M.
J. Org. Chem. 1995, 60, 1182; (b) Snider, B.; Chen, J.;
Patial, A. D.; Freyer, A. Tetrahedron Lett. 1996, 37,
1
.1. General procedure for the synthesis of dihydropy-
rimidin-2-one: for representative compound 4a
A mixture of stoichiometric amounts of benzaldehyde,
ethyl acetoacetate, urea and a catalytic amount of
manganese(III) acetate dihydrate in acetonitrile (15 ml)
was stirred under reflux for the appropriate time (Table
6977; (c) Rama Rao, A. V.; Gurjar, M. K.; Vasudevan,
1
). After completion of the reaction, as indicated by TLC
J. J. Chem. Soc., Chem. Commun. 1995, 1369.
analysis, the solvent was evaporated, dried and washed
with water and the resulting solid compound was filtered
under suction and recrystallized from isopropanol to
afford the pure product 4a.
5. Folkers, K.; Harwood, H. J.; Johnson, T. B. J. Am.
Chem. Soc. 1932, 54, 3751.
6. (a) Zavyalov, S. I.; Kulikova, L. B. Khim. Farm. Zh.
1992, 126, 116; (b) Gupta, R.; Gupta, A. K.; Paul, S.;
Kachroo, P. L. Ind. J. Chem. 1995, 34B, 151; (c) Hu,
E. H.; Sidler, D. R.; Dolling, U. H.; Patane, M. A.
PCT Int. Appl. WO 9,721,687; Chem. Abstr. 1997, 127,
1
.2. Spectroscopic data for compound 4a
5
Solid, mp 203–205°C (isopropanol), yield 96% (lit., mp
1
21750v.
. O’Reilly, B. C.; Atwal, K. S. Heterocycles 1987, 26,
185.
−
1
2
02°C); IR (KBr): w 3242, 3116, 1725, 1700, 1647 cm ;
7
8
1
H NMR (DMSO-d ): l 1.12 (t, 3H, J=7.5 Hz, CH ),
6
3
1
2
.28 (s, 3H, CH ), 4.03 (q, 2H, J=7.5 Hz, OCH ), 5.17
3
2
. (a) Shutalev, A. D.; Kuksa, V. A. Khim. Geterotsikl.
Soedin 1997, 105; (b) Shutalev, A. D.; Kishko, E. A.;
Sivova, N.; Kuzenetsov, A. Y. Molecules 1998, 3, 100.
. (a) Wipf, P.; Cunningham, A. Tetrahedron Lett. 1995,
(
(
d, 1H, J=3.0 Hz, H-4), 7.22–7.41 (m, 5H, Harom), 7.78
brs, 1H, NH), 9.22 (brs, 1H, NH).
9
3
6, 7819; (b) Studer, A.; Jeger, P.; Wipf, P.; Curran, D.
Acknowledgements
P. J. Org. Chem. 1997, 62, 2917.
1
0. (a) Atwal, K. S.; O’Reilly, B. C.; Gougoutas, J. Z.;
Malley, M. F. Heterocycles 1987, 26, 1189; (b) Barlu-
enga, M. T.; Rubio, V.; Gotor, V. J. Chem. Commun.
K.A.K. thanks the CSIR, New Delhi for the award of
a Fellowship.
1979, 675.
1
1. (a) Hu, E. H.; Sidler, D. R.; Dolling, U. H. J. Org.
Chem. 1998, 63, 3454; (b) Kappe, C. O.; Falsone, S. F.
Synlett 1998, 718.
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