B. M. Smith, A. E. Graham / Tetrahedron Letters 47 (2006) 9317–9319
9319
conditions from a range of carbonyl compounds in high
yields and in very short reaction times. The reactions are
extremely simple and do not generally require chro-
matographic purification and proceed without the
requirement for inert or anhydrous reaction conditions
or elevated temperatures.
and the EPSRC National Mass Spectrometry Service,
University of Wales Swansea, UK.
References and notes
1. Kocienski, P. J. Protecting Groups; Thieme: New York,
2003.
Typical experimental procedure: To a mixture of 2-furan-
carboxaldehyde (113 mg, 1.17 mmol) and trimethyl
orthoformate (250 mg, 2.35 mmol) in dichloromethane
(15 mL) at room temperature was added indium triflate
(3.3 mg, 0.5 mol %) and the reaction mixture stirred at
room temperature for 3 min. A further portion of the
catalyst (3.3 mg, 0.5 mol %) was added at this time
and the reaction mixture stirred for a further 2 min.
Next, the mixture was passed through a short plug of
neutral alumina which was then washed with additional
dichloromethane (2 · 5 mL) and the solvent was re-
moved under reduced pressure to give the product 2-
2. (a) Wenkert, E.; Goodwin, T. E. Synth. Commun. 1977, 7,
409–415; (b) Torok, D. S.; Figueroa, J. J.; Scott, W. J. J.
Org. Chem. 1993, 58, 7274–7276; (c) Lu, T.-J.; Yang, J.-F.;
Sheu, L.-J. J. Org. Chem. 1995, 60, 2931–2934; (d) Yu, M.;
Pagenkopf, B. L. Tetrahedron 2003, 59, 2765–2771.
3. (a) Gemal, A. L.; Luche, J. H. J. Org. Chem. 1979, 44,
4187–4189; (b) Ishihara, K.; Karumi, Y.; Kubota, M.;
Yamamoto, H. Synlett 1996, 839–841; (c) Clerici, A.;
Pastori, N.; Porta, O. Tetrahedron 1998, 54, 15679–15690;
(d) Firouzabadi, H.; Iranpoor, N.; Karimi, B. Synlett 1999,
321–323; (e) Leonard, N. M.; Oswald, M. C.; Freiberg, D.
A.; Nattier, B. A.; Smith, R. C.; Mohan, R. S. J. Org.
Chem. 2002, 67, 5202–5207; (f) Kumar, R.; Chakraborti,
A. K. Tetrahedron Lett. 2005, 46, 8319–8323.
4. Fringuelli, F.; Piermatti, O.; Pizzo, F.; Vaccaro, L. Curr.
Org. Chem. 2003, 7, 1661–1689.
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2004, 1727–1730.
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1
furancarboxaldehyde dimethyl acetal (165 mg, 99%); H
NMR (CDCl3; 400 MHz) d = 3.28 (s, 6H), 5.37 (s,
1H), 6.29 (m, 1H), 6.35 (m, 1H), 7.34 (m, 1H); 13C
NMR (CDCl3; 100 MHz) d = 151.3, 142.9, 110.5,
108.9, 98.4, 53.2; mmax (film)/cmÀ1 (neat) 2942, 2896,
2833, 1346, 1190, 1053, 976 and 738; MS (EI) m/z 142;
HRMS (EI) calcd for C9H10O3 (M+) 142.0624, found
(M+) 142.0624.
8. Indium trichloride has been reported to be a poor catalyst
for acetal formation in the absence of trimethyl orthofor-
mate; Kim, Y.-J.; Varma, R. S. Tetrahedron Lett. 2005, 46,
7447–7449.
Acknowledgements
9. An aqueous work-up of the reaction mixture led to a rapid
and complete hydrolysis of the acetal back to the corre-
sponding carbonyl compound.
The authors thank the Engineering and Physical Sci-
ences Research Council for financial support (BMS)