Description:
<jats:title>Abstract</jats:title><jats:p><jats:bold>Photochemistry of α,β‐epoxyketones: γ‐H‐abstraction <jats:italic>versus</jats:italic> epoxyketone‐rearrangement.</jats:bold></jats:p><jats:p>The photochemical behaviour of conformationally mobile α,β‐epoxyketones that could undergo competing reactions has been studied. The UV.‐irradiation of <jats:bold>5</jats:bold> yields the stereoisomeric cyclobutanols <jats:bold>9</jats:bold> and <jats:bold>10</jats:bold> as well as the fragmentation product <jats:bold>11</jats:bold>. Irradiation of <jats:bold>6</jats:bold> gives only the cyclobutanols <jats:bold>12</jats:bold> and <jats:bold>13</jats:bold>, whereas <jats:bold>4</jats:bold> and <jats:bold>8</jats:bold> in inert solvents yielded only intractable gums. The non‐occurrence of the typical isomerization of α,β‐epoxylketones to the corresponding β‐diketones is attributed to steric factors.</jats:p>