Stereoselective Addition of Singlet Oxygen to Naphthalenes and Transformation to Optically Active Peroxides
University of Hyogo, Graduate School of Material Science, Kohto, Kamigori, Hyogo 678-1297, Japan
Reaction of singlet oxygen with the naphthalene 1 containing a carboxylic acid side chain gave a mixture of diastereomeric hydroperoxides 2a-c. The stereoselectivity depends on the concentration of the substrate 1; the fraction of 2a increases with the increase of the concentration of 1. The reaction in non-polar benzene or at lower temperature also gave more 2a. We propose that the stereoselectivity is controlled by hydrogen-bonding association of the substrate 1 at the higher concentration of 1 and at the lower temperature. The association of the carboxylic acid side-chain may induce steric hindrance for addition of singlet oxygen to increase the stereoselectivity. Proton NMR chemical shift of 1 depends on the concentration of 1 and temperature, and this is consistent with the association of the carboxylic acid.
Elimination of chiral auxiliary of 2 was carried out under acidic conditions to give optically active hydroperoxide 3 (up to 94% enantiomeric excess). Stereoselective reaction of 2 with siloxyalkenes also gave perlactone and perhemiacetal as optically active form.
Presentation: oral at 18th Conference on Physical Organic Chemistry, Symposium 2, by Morifumi Fujita
See On-line Journal of 18th Conference on Physical Organic Chemistry
Submitted: 2006-05-31 11:12 Revised: 2009-06-07 00:44
|© 1998-2021 pielaszek research, all rights reserved||Powered by the Conference Engine|