Regioselectivity of the Singlet Oxygen Ene Reaction (Schenck Reaction) with Vinylsilanes

1994 ◽  
Vol 59 (12) ◽  
pp. 3335-3340 ◽  
Author(s):  
Waldemar Adam ◽  
Markus J. Richter
Keyword(s):  
Singlet Oxygen ◽  
Ene Reaction

Photooxygenation in polymer matrices: En route to highly active antimalarial peroxides

2005 ◽  
Vol 77 (6) ◽  
pp. 1059-1074 ◽  
Author(s):  
Axel G. Griesbeck ◽  
Tamer T. El-Idreesy ◽  
Anna Bartoschek
Keyword(s):  
Singlet Oxygen ◽  
Protoporphyrin Ix ◽  
Polymer Matrices ◽  
Allylic Alcohols ◽  
Ene Reaction ◽  
Highly Active ◽  
Determining Factors ◽  
Broad Variety ◽  
Covalently Linked

Photooxygenation involving the first excited singlet state of molecular oxygen is a versatile method for the generation of a multitude of oxy-functionalized target molecules often with high regio- and stereoselectivities. The efficiency of singlet-oxygen reactions is largely dependent on the nonradiative deactivation paths, mainly induced by the solvent and the substrate intrinsically. The intrinsic (physical) quenching properties as well as the selectivity-determining factors of the (chemical) quenching can be modified by adjusting the microenvironment of the reactive substrate. Tetraarylporphyrins or protoporphyrin IX were embedded in polystyrene (PS) beads and in polymer films or covalently linked into PS during emulsion polymerization. These polymer matrices are suitable for a broad variety of (solvent-free) photooxygenation reactions. One specific example discussed in detail is the ene reaction of singlet oxygen with chiral allylic alcohols yielding unsaturated β-hydroperoxy alcohols in (threo) diastereoselectivities, which depended on the polarity and hydrogen-bonding capacity of the polymer matrix. These products were applied for the synthesis of mono- and spirobicyclic 1,2,4-trioxanes, molecules that showed moderate to high antimalarial properties. Subsequent structure optimization resulted in in vitro activities that surpassed that of the naturally occurring sesquiterpene-peroxide artemisinin.

ChemInform Abstract: STEREOCHEMISTRY OF THE SINGLET OXYGEN, ENE REACTION WITH OLEFINS

1974 ◽  
Vol 5 (4) ◽  
pp. no-no
Author(s):  
L. M. STEPHENSON ◽  
D. E. MCCLURE ◽  
P. K. SYSAK
Keyword(s):  
Singlet Oxygen ◽  
Ene Reaction
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