P. Gogoi, D. Konwar / Tetrahedron Letters 48 (2007) 531–533
533
Synthesis 1981, 266; (c) Pallai, P.; Goodman, M. J. Chem.
Soc., Chem. Commun. 1982, 280; (d) Squadrini, F.;
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J. Am. Chem. Soc. 1985, 107, 5821; (f) Shimihihashi, Y.;
Kodama, H.; Waki, M.; Costa, T. Chem. Lett. 1988,
1821.
2. Experimental
2.1. Typical experimental procedure for the synthesis of
methyl carbamate
To a solution of benzamide (1 mmol) in methanol (7 ml),
KF/Al2O3 (2 g, 40% by weight) and NaOCl (3 ml of a
4% aqueous solution) were added and the mixture was
refluxed for 30 min. After cooling the reaction mixture
to room temperature, the solid base was filtered.
Methanol was then removed by rotary evaporation
and the residue was dissolved in EtOAc (20 ml). The
EtOAc layer was washed with water (10 ml · 3), dried
over anhydrous sodium sulfate and concentrated under
reduced pressure to give a crude product which was
purified by crystallization using petroleum ether.
3. (a) Wallis, E. S.; Lane, J. F. Org. React. 1946, 3, 267; (b)
Kajigaeshi, S.; Asano, K.; Fujasaki, S.; Kakinami, T.;
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4. (a) Senanayake, C. H.; Fredenburgh, L. E.; Reamer, R.
A.; Larsen, R. D.; Verhoeven, T. R.; Reider, P. J. J. Am.
Chem. Soc. 1994, 116, 7947; (b) Moriarty, R. M.; Chany,
C. J., II; Vaid, R. K.; Prakash, O.; Tuladhar, S. M. J. Org.
Chem. 1993, 58, 2482, and references cited therein.
5. Baumgarten, H. E.; Smith, H. L.; Staklis, A. J. Org. Chem.
1975, 40, 3554.
6. Jew, S.-S.; Park, H. G.; Park, H.-J.; Park, M.-S.; Cho,
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313.
8. Huang, X.; Seid, M.; Keillor, J. W. J. Org. Chem. 1997,
62, 7495.
9. Radlick, P.; Brown, L. R. Synthesis 1974, 290.
10. (a) Bunin, B. A. The Combinatorial Index; Academic: New
York, 1998; (b) Czarnik, A. W.; DeWitt, S. H. A Practical
Guide to Combinatorial Chemistry; American Chemical
Society: Washington, DC, 1997; (c) Nicolaou, K. C.;
Hanko, R.; Hartwig, W. Handbook of Combinatorial
Chemistry; Wiley-VCH: Weinheim, 2002.
2.2. Methyl N-(2-thiophene)carbamate (2l)
White solid; mp 88–90 ꢁC; 1H NMR (CDCl3, 300 MHz):
d 3.80 (s, 3H), 6.60 (d, 1H, J = 2.46 Hz), 6.80–6.88 (m,
2H), 7.20 (br s, 1H); 13C NMR (CDCl3, 75 MHz): d
53.82, 113.29, 118.47, 125.53, 140.67, 154.87; FTIR
(KBr): 3257, 2960, 1696, 1576, 1349, 1289, 1249,
1071 cmÀ1
;
HRMS calcd for C6H7NO2S (M+)
157.1923, found 157.4601.
11. Blass, B. E. Tetrahedron 2002, 58, 9301, and references
cited therein.
Acknowledgements
12. (a) Cicchi, S.; Corsi, M.; Goti, A. J. Org. Chem. 1999, 64,
7243; (b) Bright, Z. R.; Luyeye, C. R.; Marie Morton, A.
S.; Sedenko, M.; Landolt, R. G.; Bronzi, M. J.; Bohovic,
K. M.; Alex Gonser, M. W.; Lapainis, T. E.; Hendrickson,
W. H. J. Org. Chem. 2005, 70, 684.
13. (a) Paquette, L. A. In Encyclopedia of Reagents for
Organic Synthesis; John Wiley & Sons, 1995; Vol. 7, p
4580; (b) Correia, J. Synthesis 1994, 1127; (c) El Achari,
A.; Coqueret, X.; Lablache-Combier, A.; Loucheux, C.
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Y.; Sefton, M. V. J. Appl. Polym. Sci. 1996, 61, 351.
14. Esch, P. M.; Hiemstra, H.; Speckamp, W. N. Tetrahedron
1992, 48, 3445.
The authors acknowledge the Director, Dr. P. G. Rao
and Dr. N. Borthakur, HOD, Synthetic Organic Chem-
istry Division, the Analytical Division of RRL, Jorhat,
Assam, India, for their help. P.G. thanks CSIR, New
Delhi, for the research fellowship.
References and notes
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1978, 19, 437; (b) Waki, M.; Kitajima, Y.; Zumiya, N.