Formation of Bicyclic Ethers from Lewis Acid Promoted Cyclizations of Cyclic Oxonium Ions
作者:Pradip K. Sasmal、Martin E. Maier
DOI:10.1021/ol025570d
日期:2002.4.1
Oxacycles carrying a vinyl group and an acetal were extended with a cyclization terminator (vinyl silane or vinyl sulfide) by Suzuki coupling. Treatment with Lewis acid induced cyclization to provide bicyclic ethers in reasonable yields. In the case of the vinyl silane, an ene-like mechanism is preferred, whereas the thioenol ether enters into a Prins-type reaction channel. In one instance, the bicyclic
Ring-fused and spiro cyclopentenones by Ni(CO)4-promoted intermolecular carbonylative cycloaddition of acetylenes with 3-halo- and 1-(halomethyl)cycloalkenes
作者:Lluis Pages、Amadeu Llebaria、Francisco Camps、Elies Molins、Carles Miravitlles、Josep M. Moreto
DOI:10.1021/ja00052a047
日期:1992.12
The title carbonylativecycloaddition of five- to eight-member ring 3-halo- and 1-(halomethyl)cycloalkenes with different acetylenes was studied. From moderate to good yields of ring-fused and spiro cyclopentenone derivatives were obtained, especially in the reaction with acctylenes bearing electron-withdrawing substituents by propa selection of the reaction conditions to avoid the acetylene polyinsertion