214967-70-1Relevant articles and documents
A novel aldol condensation alternative: α,β-unsaturated aldehydes from 3-hydroxy-1-alkynes via dihydrodioxepins
Wei, Heng-Xu,Schlosser, Manfred
, p. 1738 - 1743 (2007/10/03)
The controlled aldol condensation between an aliphatic ketone and an acetaldehyde equivalent remains a challenge. One solution to this evergreen problem consists of the nucleophilic addition of acetylene to the ketone and the subsequent isomerization of the resulting 3-hydroxy-1-alkyne to the corresponding 2-alkenal. So far, however, the latter Step could only be executed with acid-insensitive substrates. We now present a milder, three-step method which extends the scope of the procedure considerably. In the first step, the 3-hydroxy-1-alkynes are converted into 2-propynyl ethylene glycol monoethers; these then undergo base-catalyzed cyclization to give the dihydro-1,4-dioxepins, which are hydrolyzed in acidic medium in the third and final step.
