structure analysis. The cycloaddition of carbonyl ylides with the compounds having both CO and CC groups was found to be chemo- and regioselective. Interestingly, an unusual ring enlargement of cycloadducts 34, 36, and 41 derived from CO group addition was observed, affording epoxyoxocin-4(5H)-one and epoxyoxonin-5(6H)-one frameworks. Examples for the tandem cyclization−cycloaddition−ring enlargement
一系列对称和不对称α,β不饱和酮的诸如arylmethylidenecycloalkanones(16,19),双(亚苄基)环烷酮(21,23,27),bisdiphenylnonatetraenones(30),和双(苯基亚
丙烯基)环烷酮(33,38,合成42)并使其与各种α-重
氮酮进行
铑(II)催化的串联环化-环加成反应。这些反应,得到螺环氧桥连的
四氢吡喃酮,螺环氧桥oxepanone(41,43),epoxyoxocin-4(5 ħ) -酮(35,37)和环氧
肟酸5(6 H)-一(40)骨架从相对简单的前体开始。通过单晶X射线结构分析表征了几种产品的区域和立体
化学以及固态结构安排。发现具有两个C 0和C C基团的化合物对羰基亚烷基的环加成是
化学和区域选择性的。有趣的是,cycloadducts的一个不寻常的扩环34,36,和41衍生自C观察到O基团加成,得到epoxyoxocin-4(5