Unexpected catalysis: aprotic pyridinium ions as active and recyclable Brønsted acid catalysts in protic media
Barbara Procuranti and Stephen J. Connon*
*Centre for Synthesis and Chemical Biology, School of Chemistry, University of Dublin, Trinity College, Dublin 2, Ireland, Email: connonstcd.ie
B. Procuranti, S. J. Connon, Org. Lett., 2008, 10, 4935-4938.
DOI: 10.1021/ol802008m (free Supporting Information)
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Simple pyridinium salt derivatives unexpectedly catalyze highly efficient acetalizations of aldehydes at ambient temperature. The aprotic catalyst promotes the formation of benzaldehyde dimethyl acetal at low loadings more efficiently than a protic Brønsted acid catalyst with a pKa of 2.2. The ionic catalyst can be readily recovered by precipitation and reused without loss of activity.
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