T. Gimisis, P. Arsenyan, Dimitris Georganakis
Aug 1, 2003
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0
Influential Citations
6
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Journal
Synlett
Abstract
Abstract: O - tert -Butyldimethylsilylimidazolyl aminals are N , O -acetals that form readily from aldehydes, and although they func-tion as aldehyde stabilizing and protecting groups under variousconditions, we report here that they react with organolithium re-agents similarly to the parent aldehydes. The mechanism involvesthe intermediate formation of a 2-imidazolyl anion as is exemplifiedby the isolation of 2-TBDMS-imidazole. Substitution of the imida-zolyl moiety at the 2-position renders these aldehyde derivativesstable to organolithium reagents, thus allowing for the tuning oftheir reactivity. Key words: aldehydes, N , O -acetals, protecting groups, organome-tallic reagents, Brook rearrangements The silylation of aldehydes 1 and ketones 2,3 with N -(tri-methylsilyl)-imidazole as well as other silylated azoles 2,3 has been known for more than thirty years to produce tri-methylsilyl N , O -acetals and ketals. Nevertheless, thesechromatographically labile carbonyl derivatives have notbeen used extensively as synthetic intermediates. Recent-ly, a