Reactions of 1,2,4-Oxadiazole[4,5-a]piridinium Salts with Alcohols: the Synthesis of Alkoxybutadienyl 1,2,4-Oxadiazoles |
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Authors: | Dr Mattia Moiola Dr Marco Leusciatti Prof Dr Paolo Quadrelli |
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Institution: | Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 – Pavia, Italy |
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Abstract: | 1,2,4-Oxadiazole4,5-a]piridinium salts add alcohols and alkoxides to undergo electrocyclic ring opening affording alkoxybutadienyl 1,2,4-oxadiazole derivatives. The pyridinium salts represent a special class of Zincke salts that are prone to rearrange to give alkoxybutadienyl 1,2,4-oxadiazoles when treated with suitable nucleophiles or, alternatively, to give pyridones in the presence of bicarbonate. The pivotal tuning of the experimental conditions leads to a straightforward synthesis of valuable 1,2,4-oxadiazole derivatives. The mechanism is also discussed in the light of previous observations. |
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Keywords: | Nitrile oxides 1 3-dipolar cycloadditions Zincke salts oxadiazoles alkoxybutadienyl derivatives |
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