V. P. Raje et al. / Tetrahedron Letters 46 (2005) 835–837
837
These examples clearly indicate that N-aryl or N-alkyl
3-oxoalkyl)carbamates can be easily synthesised using
6. (a) Wabnitz, T. C.;Yu, j. Q.;Spencer, J. B. Synlett 2003,
070–1072;(b) Kobayashi, S.;Kakumoto, K.;Sugiua, M.
Org. Lett. 1992, 4, 1319–1322.
1
(
Sn modified zeolite Hb. The quenching experiment (ter-
minating the reaction half way through, separation of
the catalyst, allowing the reaction to continue in the fil-
trate) showed that leaching was not significant, as the
reaction did not proceed once the catalyst had been sep-
arated from the reaction mixture.
7
. (a) The Agrochemicals Handbook, 2nd ed.;Royal Society
of Chemistry: Cambridge, UK, 1987;(b) Mohumed, N.;
Paull, K. D.;Narayanan, V. L. J. Pharm. Sci. 1985, 74,
8
31–836.
8
. (a) Green, T. W.;Wuts, P. G. M. Protective Groups in
Organic Synthesis, 2nd ed.;Wiley: New York, 1999;pp
5
J. Org. Chem. 1997, 62, 6968–6973.
9. Pandey, R. K.;Dagade, S. P.;Dongare, M. K.;Kumar, P.
Synth. Commun. 2003, 33, 4019–4027.
0. (a) Holderich, W.;Hesse, M.;Naumann, F.
Chem., Int. Ed. 1988, 27, 226–246;(b) Zeolites for Cleaner
Technologies;Guisnet, M., Gilson, J. P., Eds.;Imperial
Collage: London, 2002.
1. (a) Singh, D. U.;Singh, P. R.;Samant, S. D. Tetrahedron
Lett. 2004, 45, 4805–4807;(b) Pai, S. G.;Bajpai, A. R.;
Deshpande, A. B.;Samant, S. D. J. Mol. Catal. A: Chem.
03–550;(b) Xiuo, X. Y.;Ngu, K.;Chao, C.;Patel, D. V.
In summary, we have developed an environmentally
friendly and reusable catalyst for the one-pot aza-
Michael reaction to produce N-aryl as well as N-alkyl
1
Angew.
(
3-oxoalkyl)carbamate
from
the
corresponding
1
5
amines. The procedure is clean operationally and sim-
ple. To our knowledge this is the first reported Lewis
acid supported zeolite (Hb-SnA) for aza-Michael
reactions.
1
2
000, 156, 233–243;(c) Singh, D. U.;Samant, S. D. J.
Mol. Catal. A: Chem. 2004, 233, 111–116;(d) Pai, S. G.;
Bajpai, A. R.;Deshpande, A. B.;Samant, S. D. Synth.
Commun. 1997, 27, 379–384;(e) Bajpai, A. R.;Deshpande,
A. B.;Samant, S. D. Synth. Commun. 2000, 30, 2785–
2791.
Acknowledgements
The authors thank the G. D. Gokhale Charitable Trust,
Mumbai and DST(SP/S1/H06/2000) New Delhi for
financial assistance
12. Sato, T.;Wakahara, Y.;Otera, J.;Nozaki, H.;Fukuzami,
S. J. Am. Chem. Soc. 1991, 113, 4028–4030.
1
3. Typical procedure for catalyst preparation: to anhydrous
SnCl (15 g) dissolved in deionised water (60 mL), Hb-
4
References and notes
zeolite (10 g) was added over a period of 10 min. The
resultant slurry was stirred at room temperature (30 °C)
for 5 h. The resultant catalyst was filtered and washed with
1
2
. (a) Misra, N.;Luthra, R.;Singh, K. L.;Sushil, K. In
Comprehensive Natural Products Chemistry;Barton, D.,
Nakanishi, H. R., Meth-Cohn, O., Eds.;Pergamon:
Oxford, 1999;Vol. 4, pp 25–60;(b) Staunton, J.;Wilkin-
son, B. Top. Curr. Chem. 1997, 195, 49–92.
À
deionised water until free from Cl ions (tested by silver
nitrate). The catalysts were dried at 80 °C to obtain Hb-
SnA.
14. General procedure for one-pot synthesis: to a mixture of
Hb-SnA (0.2 g, 0.27 mmol of Sn) and methyl chlorofor-
mate (5 mmol) in 5 mL of acetonitrile, amine (5 mmol)
dissolved in 5 mL of acetonitrile added dropwise. The
reaction mixture was stirred at room temperature until
the completion of the reaction as indicated by TLC. To the
resulting mixture, methyl vinyl ketone (6 mmol) was
added and the reaction was stirred until the completion
as indicated by TLC. The reaction mixture was filtered
and evaporated. The crude product was purified by
column chromatography.
. (a) Cardillo, G.;Tomasini, C. Chem. Soc. Rev. 1996, 25,
1
17–128;(b) Devine, P. N.;Heid, R. M., Jr.;Tschaen, D.
M. Tetrahedron 1997, 53, 6739–6746;(c) Drury, W. J.;
Ferraris, D.;Cox, C.;Young, B.;Leckta, T. J. Am. Chem.
Soc. 1998, 120, 11006–11009;(d) Abele, S.;Seebach, D.
Eur. J. Org. Chem. 2000, 1, 1–15;(e) Jung, M. E. In
Comprehensive Organic Synthesis;Trost, B. M., Fleming,
I., Eds.;Pergamon: Oxford, 1991;Vol. 4, pp 30–45.
. Arend, M.;Westermann, B.;Risch, N. Angew. Chem., Int.
Ed. 1998, 37, 1044–1070.
3
4
1
. (a) Kawatsuraand, M.;Hartwig, J. W. Organometallics
2
15. All compounds were characterised by H NMR, IR and
CHN analysis.
001, 20, 1960–1964;(b) Shriwastava, N.;Banik, B. K.
J. Org. Chem. 2003, 68, 2109–2114;(c) Bartoli, G.;Basco,
M.;Marcantoni, E.;Petrini, M.;Sambri, L.;Torregiani,
E. J. Org. Chem. 2001, 66, 9052–9055;(d) Nakama, K.;
Seki, S.;Kanemasa, S. Tetrahedron Lett. 2001, 42, 6719–
Spectral data for methyl N-(4-bromophenyl)-N-(3-oxobutan-
1-yl)carbamate: IR (neat): cm 3036, 2974, 1707, 1466,
À1
1
1378, 1018, H NMR (300 MHz, CDCl
3
): d 7.48 (d,
J = 8.7 Hz, 2H), 7.05 (d, J = 8.7 Hz, 2H), 3.9 (t,
J = 7.2 Hz, 2H), 3.68 (s, 3H), 2.75 (t, J = 7.5 Hz, 2H),
2.18 (s, 3H), Anal. Calcd for C12H14BrNO : C, 48.02;H,
3
4.68;Br, 26.51;N, 4.64. Found: C, 48.19;H, 4.65;Br,
26.49;N, 4.63%.
6
722.
. (a) Xu, L. W.;Xia, C. G.;Hu, X. X. Chem. Commun.
003, 2570–2571;(b) Xu, L. W.;Xia, C. G. Tetrahedron
Lett. 2004, 45, 4507–4510.
5
2