Stereoselective hydrogen transfer reactions of vinyl radicals: Cyclization of alkynyl iodides by Unimolecular Chain Transfer from silicon hydrides
作者:Angeles Martinez-Grau、Dennis P. Curran
DOI:10.1016/s0040-4020(97)00257-3
日期:1997.4
hexynyl and heptynyl iodides proceeds stereoselectively to give either E- or Z-exocyclic double bonds depending on the type of precursor and radical chain used. In UniMolecularChain Transfer (UMCT) reactions, the intramolecular abstraction of hydrogen by the intermediate vinyl radical leads exclusively to the E-isomer while the traditional tin hydride method usually provides the Z-isomer with good
Samarium(II) iodide mediated intramolecular reductivecoupling of carbonyl groups and alkynes in the presence of HMPA and t-BuOH was successfully performed to provide cyclized products. Some cyclic compounds containing a heteroatom such as oxygen or nitrogen were also efficiently prepared by this coupling reaction.