Used in combination with the Sharpless asymmetric epoxidation of allylicalcohols, this rearrangement represents a new approach to the synthesis of various opticallyactive β-hydroxy aldehydes, useful intermediates in natural product synthesis. The modified organoaluminum reagent, MABR is also applicable to the transformation of a variety of simple epoxides to carbonyl compounds with high efficiency
An Unusual Ring-Contraction/Rearrangement Sequence for Making Functionalized Di- and Triquinanes
作者:Chinta Nagaraju、Kavirayani R. Prasad
DOI:10.1002/anie.201407680
日期:2014.10.6
A novel ring contraction/rearrangement sequence leading to functionalized 2,8‐oxymethano‐bridged di‐ and triquinane compounds is observed in the reaction of various substituted 1‐methyl‐4‐isopropenyl‐6‐oxabicylo[3.2.1]octan‐8‐ones with Lewis acids. The reaction is novel and is unprecedented for the synthesis of di‐ and triquinane frameworks.
A convergent enantioselectivetotalsynthesis of cotylenin A is described. The A-ring fragment, prepared via the catalytic asym-metric intramolecular cyclopropanation developed in our laboratory, and the C-ring fragment, prepared from a known chiral compound via a modified acyl radical cyclization, were successfully assembled by the Utimoto coupling reaction. The formidable carbocyclic eight-membered
描述了子叶素 A 的收敛对映选择性全合成。通过我们实验室开发的催化不对称分子内环丙烷化制备的 A 环片段和由已知手性化合物通过修饰的酰基自由基环化制备的 C 环片段通过 Utimoto 偶联反应成功组装。通过钯介导的环化有效地构建了子叶素 A 的强大碳环八元环。支架中的所有羟基都被立体选择性地引入,并开发了一种改良的还原剂 Me4NBH(O2CiPr)3。糖部分片段是通过三个连续的碳氧键形成反应制备的,糖基化是使用万的方案完成的。
Borinic Acid/Halide Co-catalyzed Semipinacol Rearrangements of 2,3-Epoxy Alcohols
作者:Kashif Tanveer、Seung-Joon Kim、Mark S. Taylor
DOI:10.1021/acs.orglett.8b02248
日期:2018.9.7
A new mode of catalysis of the semipinacol rearrangement of 2,3-epoxy alcohols is described. In combination with a halide salt additive, diarylborinic acids promote a Type II rearrangement that occurs with net retention of configuration. This unusual stereochemical outcome is consistent with a mechanism involving regioselective ring opening of the epoxy alcohol by halide, followed by rearrangement
Total enantioselective synthesis of the marine sesquiterpene nanaimoal
作者:Tomoki Omodani、Kozo Shishido
DOI:10.1039/c39940002781
日期:——
The first enantioselective totalsynthesis of (–)-nanaimoal 1 has been achieved from geraniol and the absolute configuration of the only existing quaternary stereogenic centre was found to be (R).