Stereocontrolled Synthesis of Heteroannular Acetals from Functionalized 1,5-Enynes via Radical Cascades—Construction of Quaternary and 1,2-Diquaternary Centres in Polycyclic Systems
作者:O Rhode、H.M.R Hoffmann
DOI:10.1016/s0040-4020(00)00592-5
日期:2000.8
Sequential, radical-mediated cyclizations of 1,5-enynes have been evaluated with respect to structure, stereochemistry and reactivity. In series A 5-exo-trig, 6-endo-dig cascades are favoured. The unusual 6-endo-dig cyclization is dictated by ring strain. Diastereomeric series B tolerates leakage into the 5-exo-trig, 5-exo-dig sequence, especially if a quaternary carbon centre is established during
Gold-catalyzed reactivity of 3-silyloxy-1,5-enynes: a synthetic tool for the synthesis of complex structures and its limitations
作者:Helge Menz、Jörg T. Binder、Benedikt Crone、Alexander Duschek、Timm T. Haug、Stefan F. Kirsch、Philipp Klahn、Clémence Liébert
DOI:10.1016/j.tet.2008.11.103
日期:2009.2
Gold-catalyzed reactions of 3-silyloxy-1,5-enynes in the presence of sterically demanding alcohols afford 4-acylcyclopentenes. The cascade process most likely proceeds through a 6-endo-dig carbocyclization and subsequent pinacol-type rearrangement. Studies that define scope and limitations of the cyclization–migration strategy are also described. An alternative cascade yields highly substituted aryls