Oxidation of cis-cis-1,5-cyclooctadiene with hydrogen peroxide gives cis-5-cyclooctene-trans-1,2-diol (3) which is converted to cis-5-cyclooctene-1,2-dione (6) on treatment with dimethyl sulfoxide and acetic anhydride. Bromination of 6 is accompanied by transannular bonding to give a dibromo keto ether 9a or b. Ketalization of 6 with ethylene glycol gives a monoketal 11 and two diketals 12 and 13 with 1,3-dioxolane and 1,4-dioxane rings, respectively. Bromination of 12 with bromine or pyridinium perbromide is accompanied by transannular bonding and fission of one of the 1,3-dioxolane rings to give a dibromo monoketal ether 15a (or b). Bromination of 12 with N-bromosuccinimide followed by dehydrobromination gives a cyclooctadiene-1,2-dione diketal 20a (or b).
用
过氧化氢氧化顺式-顺式-
1,5-环辛二烯会得到顺式-5-环
辛烯-反-1,2
-二醇(3),经过
二甲基亚砜和
乙酸酐处理后会转化为
顺式-5-环辛烯-1,2-二酮(6)。对6的
溴化反应伴随着横向环内键合,形成二
溴酮醚9a或b。用
乙二醇对6进行
缩酮化反应会得到单
缩酮11和两个具有1,3-二氧杂环戊
二醚和1,4-二氧杂环已
二醚环的双
缩酮12和13。将12与
溴或
吡啶溴酸盐进行
溴化反应会伴随着横向环内键合和一个1,3-二氧杂环戊
二醚环的裂解,形成二
溴单
缩酮醚15a(或b)。用N-
溴丁二
酰亚胺对12进行
溴化反应,然后进行脱氢
溴化反应会得到
环辛二烯-1,2-二酮双
缩酮20a(或b)。