Co-host: The Chemical Society of Japan, The Society of Synthetic Organic Chemistry, Japan (Cooperation)
Reaction of singlet oxygen with the naphthalene 1 containing lactic acid side chain gave a diastereomeric mixture of hydroperoxides. The stereoselectivity depends on the concentration of the substrate 1 and reaction temperature. 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. A major isomer of the product forms via anti-relationship between singlet-oxygen addition and carboxylic-acid addition to naphthalene stereoface. The association of the carboxylic acid side-chain may induce steric hindrance to result in the anti-addition. Proton NMR chemical shift of 1 depends on the concentration of 1 and temperature, and these dependencies can be explained by the association of the carboxylic acid.
