摘要：

The hydroxy ketone intermediates III and IV from the reaction between benzaldehyde and butanone have been prepared by the Schpf method. Treatment of either the straight-chain isomer III or the branched isomer IV with dilute alkali produced the straight-chain unsaturated ketone I. Treatment of III and IV with acid afforded I and II, respectively, with no evidence of rearrangement. The reaction between p-nitrobenzaldehyde and butanone in alkali yielded three hydroxy ketones (V, VIa and VIb) indicating that both methyl and methylene positions were attacked to a comparable extent. These results support a mechanism for the alkaline condensation in which the dehydration of the intermediate hydroxy ketones is a slow step and thus responsible for the exclusive formation of I. The formation of II in acid results from selectivity at the addition step (2) of the reaction.

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