Radical Fragmentation of 4a-hydroxy-octahydronaphthalen-1-one Derived from 3,5-dibromo-2-pyrone: Synthesis of Various Medium-Sized Rings

초록

Beta-hydroxyketones derived from Diels-Alder reaction of 3,5-dibromo-2-pyrone were tested in several ring-enlargement reactions. We found that photolysis of beta-hydroxyketone 2 in the presence of HgO and 12 results in beta-alkoxy radical, which undergo desired fragmentation. Alpha-carbonyl radical thus generated is trapped by molecular iodine to give alpha-iodo ketone medium-ring 3.