150
R. Ghosh et al. / Tetrahedron Letters 46 (2005) 147–151
Ramachander, T.; Takhi, M. Tetrahedron Lett. 1998, 39,
3263–3266; (d) InCl3: Chakraborti, A. K.; Gulhane, R.
Tetrahedron Lett. 2003, 44, 6749–6753; (e) ZrCl4: Chakr-
aborti, A. K.; Gulhane, R. Synlett 2004, 22, 627–630; (f)
RuCl3: De, S. K. Tetrahedron Lett. 2004, 45, 2919–
2922.
without any loss of its efficacy as a catalyst (Table 2,
entries 4, 7 and 21, methods A and entry 32, method
A and B), however, the composition of the recovered
zirconium complex (ZrOCl2ÆxH2O) may vary with re-
spect to the water content.
10. (a) Sc(OTf)3: Ishihara, K.; Kubota, M.; Kurihara, H.;
Yamamoto, H. J. Org. Chem. 1996, 61, 4560–4567; (b)
TMSOTf: Procopiou, P. A.; Baugh, S. P. D.; Flack, S. S.;
Inglis, G. G. A. J. Org. Chem. 1998, 63, 2342–2347; (c)
Cu(OTf)2: (i) Chauhan, K. K.; Frost, C. G.; Love, I.;
Waite, D. Synlett 1999, 22, 1743–1744; (ii) Chandra, K.
L.; Saravanan, P.; Singh, R. K.; Singh, V. K. Tetrahedron
2002, 58, 1369–1374; (d) Bi(OTf)3: Orita, A.; Tanahashi,
C.; Kakuda, A.; Otera, J. J. Org. Chem. 2001, 66, 8926–
8934; (e) Ce(OTf)3: Dalpozzo, R.; DeNino, A.; Maiuolo,
L.; Procopio, A.; Nardi, M.; Bartoli, G.; Romeo, R.
Tetrahedron Lett. 2003, 44, 5621–5624; (f) LiOTf:
Karimi, B.; Makeki, J. J. Org. Chem. 2003, 68, 4951–
4954.
11. (a) LiClO4: (i) Nakae, Y.; Kusaki, I.; Sato, T. Synlett
2001, 22, 1584–1586; (ii) Chakraborti, A. K.; Sharma, L.;
Gulhane, R.; Shivani Tetrahedron 2003, 59, 7661–7668;
(iii) Bartoli, G.; Bosco, M.; Dalpozzo, R.; Marcantoni, E.;
Massaccesi, M.; Rinaldi, S.; Sambri, L. Synlett 2003, 22,
39–42; (b) BiO(ClO4)2: Chakraborti, A. K.; Gulhane, R.;
Shivani Synlett 2003, 1805–1808.
It should be noted that unlike that of the BiOCl–acetyl
chloride combination, which has been shown to
generate BiCl3 in situ,24c,29b a similar combination of
ZrOCl2Æ8H2O–acetyl chloride does not generate ZrCl4
in situ as evidenced by the 13C NMR spectra of
ZrOCl2Æ8H2O–acetyl chloride and ZrCl4–acetyl chloride
in CDCl3 and by the GLC of the reaction mixture.30
In summary, we have demonstrated the efficiency of
ZrOCl2Æ8H2O, towards the acetylation of alcohols,
phenols, amines and thiols with acetyl chloride. The
notable special features of this methodology are the sim-
ple reaction procedure, excellent yields of products,
moderate Lewis acidity of ZrOCl2Æ8H2O, low cost, ready
availability,20 low toxicity (LD50 oral in rat: 1688mg/
kg),21 and moisture compatibility and recyclability of
the catalyst both in solution and under neat conditions.
Thus, this methodology represents a better, eco-friendly
alternative to many existing procedures and is also suit-
able for industrial application. This is the first report of
ZrOCl2Æ8H2O-based organic transformations.
12. (a) Borah, R.; Deka, N.; Sarma, J. C. J. Chem. Res. (S)
1997, 110–111; (b) Kartha, K. P. R.; Field, R. A.
Tetrahedron 1997, 53, 11753–11766.
13. Okano, T.; Miyamoto, K.; Kiji, K. Chem. Lett. 1995, 245–
246.
Acknowledgements
14. Choudary, B. M.; Kantam, M. L.; Neeraja, V.; Bandyo-
padhyay, T.; Reddy, P. N. J. Mol. Cat.: A Chem. 1999,
140, 25–29.
15. Orita, A.; Sakamoto, K.; Hamada, Y.; Mitsutome, A.;
Otera, J. Tetrahedron 1999, 55, 2910–2988.
16. Forsyth, S. A.; MacFarlane, D. R.; Thomson, R. J.; von
Itzstein, M. Chem. Commun. 2002, 714–715.
17. Yamada, S.; Sugaki, T.; Matsuzaki, K. J. Org. Chem.
1996, 61, 5932–5938.
A grant-in-aid from the CSIR, New Delhi (scheme No
01/1672/00/EMR-II) to R.G. and a junior research
fellowship to S.M. are gratefully acknowledged. The
UGC, New Delhi is thanked for providing a senior
research fellowship to A.C.
18. Allevi, P.; Ciuffreda, P.; Longo, A.; Anastasia, M.
Tetrahedron: Asymmetry 1998, 9, 2914–2915.
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