Sensitized photo-oxygenation of a wide variety of acyclic 1,3-dienes was investigated. The 1,4-cycloaddition of singlet oxygen to acyclic conjugated dienes was closely related to the thermal Diels-Alder reaction in stereospecificity, and steric and electronic effects of substituents. Reactivity order of singlet oxygen toward conjugated dienes and isolated C—C double bonds was exhibited as follows:
Ring-Opening of Unsymmetrical 1,2-Dioxines Using Cobalt(II) Salen Complexes
作者:Ben W. Greatrex、Dennis K. Taylor
DOI:10.1021/jo040241f
日期:2005.1.1
The regioselectivity of the metal-catalyzedringopening of unsymmetrical 1,2-dioxines to cis-γ-hydroxyenones was investigated using two different Co(II) salen complexes. Regioselectivity was determined by direct examination of the enone ratios and by derivitization with a stabilized phosphorus ylide. The steric influence of the substituents on the 1,2-dioxine was the primary influence on regioselectivity