M. Maltese et al. / Tetrahedron Letters 52 (2011) 483–487
487
ditrialkylsilyl enol ethers (see Jung, M. E.; Pan, Y.-G. J. Org. Chem. 1977, 42,
3961–3963).
Supplementary data
25. Murata, S.; Noyori, R. Tetrahedron Lett. 1981, 22, 2107–2108.
26. Christina, E. I.; Scott, M. R.; James, E. H. Langmuir 2004, 20, 9144–9150.
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30. The tritylating reagents have been prepared by mixing anhydrous formic or
acetic acid with equimolar quantities of trityl chloride and triethylamine in
acetonitrile or DCM at room temperature, then isolated and purified as follows:
5 min after the introduction of formic or acetic acid in the reagent mixture, the
solvent was evaporated under vacuum and the residue extracted with ether.
The suspension was filtered off and the filtrate evaporated under vacuum. In
general, the residue was used as the reagent without further purification.
Crystallization of the trityl esters 1b and 2b for analytical purposes has been
obtained by addition of n-hexane to the residue. The use of 1b or 2b in the
presence of triethylammonium chloride obtained as secondary product in their
preparations has always given lower yields of the desired product.
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33. Doyle, M. P.; De Bruyn, D. J.; Scholten, D. J. J. Org. Chem. 1973, 38, 625–
626.
Supplementary data (melting points, microanalysis and NMR)
associated with this article can be found, in the online version, at
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ethers, catalyzed by Et2O–BF3 have been employed in the oxidation of