CHED 288 |
| The current trend in nucleophilic catalysis using N-heterocyclic carbenes (NHC's) is the generation of the free carbene in situ by direct deprotonation of a suitable imidazolium salt. Although this method is experimentally expedient, it may limit the scope of the substrates amenable to organocatalysis. In particular, base-sensitive substrates may be precluded by the necessary addition of relatively strong bases to deprotonate the imidazolium salts. A viable and practical alternative is the use of preformed NHC precursors (1). This compound, when heated above room temperature, will liberate the free NHC and a molecule of chloroform (a relatively innocent byproduct). Comparative reactions indicate that 1 is capable of catalyzing the acylation of secondary alcohols at the same rate as free NHC's generated in situ with strong bases. The scope and generality of catalysis using 1 as carbene source is presented.
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Undergraduate Research Poster Session: Organic Chemistry
2:30 PM-4:30 PM, Monday, 11 September 2006 Moscone Center -- Hall D, Poster
Division of Chemical Education |
