Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
J Org Chem. 2021 Jan 1;86(1):1084-1095. doi: 10.1021/acs.joc.0c02560. Epub 2020 Dec 23.
The rearrangements of dihydrobetulin, dihydrobetulinic acid, and -lupane epoxides under acidic conditions (HCl, montmorillonite K10, and BF·EtO) were studied. The treatment of dihydrobetulin with HCl or K10 produced -lupane olefins. Their epoxidation afforded epoxides, which, in the presence of protic or Lewis acids, rearranged to dienes or lupanes bearing a bicyclo[3.3.1]nonane fragment. The structure of final products depended on the nature of the catalyst. The HCl promoted 1,4-elimination of water, whereas in the presence of BF·EtO bond migration took place preferentially. Montmorillonite K10 favored cyclization to bicyclononane.
研究了在酸性条件下（HCl、蒙脱土 K10 和 BF·EtO）二氢羽扇豆醇、二氢羽扇豆酸和 -羽扇烷环氧化物的重排。用 HCl 或 K10 处理二氢羽扇醇可得到 -羽扇烯烯烃。它们的环氧化产物是环氧化物，在质子酸或路易斯酸的存在下，重排为具有双环[3.3.1]壬烷片段的二烯或羽扇烷。最终产物的结构取决于催化剂的性质。HCl 促进水的 1,4-消除，而在 BF·EtO 的存在下，优先发生键迁移。蒙脱土 K10 有利于环化生成双环壬烷。
