Tungsten-Promoted [3+2]- and [3+3]-Cycloaddition of Epoxides with Alkynes. A Facile Enantiospecific Synthesis of Bicyclic Lactones
作者:Reniguntala J. Madhushaw、Chien-Le Li、Kuo-Hui Shen、Chu-Chen Hu、Rai-Shung Liu
DOI:10.1021/ja0106016
日期:2001.8.1
Synthesis of Bicyclic Pyrane Derivatives via Tungsten-Mediated [3 + 3] Cycloaddition of Epoxides with Tethered Alkynes
作者:Kuo-Hui Shen、Shie-Fu Lush、Tseng-Li Chen、Rai-Shung Liu
DOI:10.1021/jo010698e
日期:2001.11.1
Propargyltungsten compounds bearing a tethered epoxide were prepared in short steps from readily available materials. In the presence of various Lewis acids, BF(3).Et(2)O catalysts (25 mol %) most effectively promote the [3 + 3] cycloaddition of the epoxide with its tethered propargyltungsten group, delivering bicyclic pyranyltungsten compounds in reasonable yields. This cyclization proceeds highly