Diastereoselective Synthesis of 1,2,3-Substituted Potassium Cyclopropyl Trifluoroborates via an Unusual Zinc-Boron Exchange
作者:André B. Charette、Simon Mathieu、Jean-François Fournier
DOI:10.1055/s-2005-871557
日期:——
Diastereoselective cyclopropanation of an allylic alcohol with a gem-dizinc carbenoid followed by an unusual zinc-boron exchange and further treatment with excess KHF2 afforded 1,2,3-syn-cis-substituted cyclopropyl trifluoroborates in 58-63% overall yields. The potassium cyclopropyl trifluoroborates underwent Suzuki-Miyaura cross-coupling reactions to give 1,2,3-functionalized cyclopropanes in good yields. Finally, an oxidation-epimerization sequence gave access to 1,2,3-trans-substituted cyclopropyl trifluoroborate.
一种烯丙醇与一种 gem-dizinc 类碳化合物进行非对映选择性环丙烷化反应,然后进行不寻常的锌-硼交换,再用过量的 KHF2 进一步处理,得到了 1,2,3-顺式-顺式取代的环丙基三氟硼酸盐,总产率为 58-63%。环丙基三氟硼酸钾经过 Suzuki-Miyaura 交叉偶联反应得到 1,2,3-官能化环丙烷,收率良好。最后,通过氧化-epimerization 顺序可以得到 1,2,3-反式取代的环丙基三氟硼酸盐。