1, 3-Dioxin-4-ones having fluorine or a trifluoromethyl group at the 5-position were used as the π2 components in Diels-Alder reactions with 1-oxygenated dienes. Use of high-perssure conditions was the essential requisite. While the 5-flurodioxinones were photolabile, the corresponding trifluoromethyl derivatives participated as the enone components in [2+2]photocycloaddition to alkenes, Ring-opening reactions of these adducts by acetal bond cleavage gave cyclobutanes and cyclohexanes. Diels-Alder reactions of the fluorinated homochiral dioxinones having l-menthone at the acetal position with Danishefsky diene proceeded in a completely diastereoselective manner to give single adducts.
在Diels-Alder反应中,
1,3-二噁烷-4-酮在5位含
氟或三
氟甲基基团的化合物被用作π2组分,与1-氧化的二烯反应。使用高压条件是必要的要求。虽然5-
氟二噁烷酮是光敏的,但相应的三
氟甲基衍
生物作为enone组分参与与烯烃的[2+2]光环加成。这些加合物通过
缩醛键断裂的开环反应生成
环丁烷和
环己烷。具有
l-薄荷酮作为
缩醛位置的
氟化手性
二噁烷酮与Danishefsky二烯的Diels-Alder反应以完全的非对映选择性进行,给出单一的加合物。