THE DIELS-ALDER AND RING ENLARGEMENT REACTIONS OF 1-CYCLOBUTENYL KETONES. PREPARATION OF 1-ACETYL-1,3,5-CYCLOOCTATRIENES
The Diels-Alder reaction of 1-cyclobutenyl ketones with various 1,3-dienes in the presence of Lewis acid as a catalyst gave cycloadducts in good yields. 4-Acetylcyclooctadienones and 1-acetyl-1,3,5-cyclooctatrienes are obtained via the bicycloocta-2,4-dienes by the transformation to the trimethylsilyl enol ether or the allylic bromination with N-bromosuccinimide followed by dehydrobromination of the cycloadducts.
