Rhodium-Catalyzed Ring Expansion of Cyclopropanes to Seven-membered Rings by 1,5 CC Bond Migration
作者:Xiaoxun Li、Min Zhang、Dongxu Shu、Patrick J. Robichaux、Suyu Huang、Weiping Tang
DOI:10.1002/anie.201104861
日期:2011.10.24
of rhodium: Highly functionalized seven‐membered rings were prepared from substitutedcyclopropanes by a RhI‐catalyzed tandem isomerization reaction. The π‐acidic RhI catalyst promoted the formation of an allene intermediate by a 1,3 acyloxy migration of a propargyl ester and a subsequent net 1,5 migration of a cyclopropane CC bond.
A rhodium-catalyzed [7 + 1] reaction of exocyclic 1,3-dienylcyclopropanes and carbon monoxide has been developed to synthesize eight-membered carbocycle-embedded bicyclic and tricyclic molecules. In addition, ab initio calculations were conducted to reveal the reaction mechanism.
Bringing it all together: [Rh(CO)2Cl}2]‐catalyzed two‐component [(5+2)+1] cycloaddition of ene‐vinylcyclopropanes with various tether types and substituents with CO has been designed for the one‐pot synthesis of fused tricyclic cyclooctenones with atom and step economies.