Improved Syntheses and Some Selective Transformations of 2,2,4,4-Tetrachloro-8-oxabicyclo[3.2.1]oct-6-en-3-ones
作者:Stefan Sendelbach、Rüdiger Schwetzler-Raschke、Andreas Radl、Roland Kaiser、Gerhard H. Henle、Hilmar Korfant、Stefan Reiner、Baldur Föhlisch
DOI:10.1021/jo972037g
日期:1999.5.1
couple leads to the corresponding oxabicyclic ketones 4. On catalytic hydrogenation of the tetrachlorooxabicyclooctenones 3a-c hydrogenolysis of the exo-carbon-chlorine bonds occurs, leading to the endo-2,endo-4-dichloro-8-oxabicyclooctan-3-ones 8a-c. With lithium aluminum hydride and Grignard reagents, 8a and 3a form the endo-3-alcohols 12a-c and 13, respectively, the latter with uncertain configuration
甲基和链烯基取代的呋喃1b-h与五氯丙酮(2)和2,2,2-三氟乙氧基钠溶液反应,以高收率形成标题化合物3b-h。呋喃1i-m在侧链上带有氧或硫杂原子,可获得中等收率。[4 + 3]环加合物3与Zn-Cu对的脱氯反应生成相应的氧杂双环酮4。在四氯氧杂双环辛烯酮3a-c催化加氢时,exo-碳-氯键发生氢解,从而导致内环2 ,endo-4-dichloro-8-oxabicyclooctan-3-ones 8a-c。用氢化铝锂和格氏试剂,8a和3a分别形成3型内醇12a-c和13,后者在C-3处的构型不确定,且立体选择性高。脱氯的氧杂环辛烯酮4b,4f中的醚桥 可以通过三氟甲磺酸三甲基甲硅烷基酯/三乙胺将4g裂解,得到托酮5b,5f和5g。将1,5-二甲基-8-氧杂双环[3.2.1] oct-6-en-3-one(4c)加氢,然后进行Wolff-Kishner还原,得到1,5-二甲基-8-氧杂双环[3