26592-92-7Relevant articles and documents
Manganese(III)-Mediated Carbon-Carbon Bond Formation in the Reaction of Xanthenes with Active Methylene Compounds
Nishino, Hiroshi,Kamachi, Hironori,Baba, Harumi,Kurosawa, Kazu
, p. 3551 - 3557 (2007/10/02)
Oxidation of xanthenes with manganese(III) acetate in the presence of active methylene compounds such as 1,3-dicarbonyl compounds, malononitrile derivatives, acetone, and nitromethane selectively gives 9-substituted xanthene derivatives in good yields.A similar oxidation of thioxanthene also yields 2-(9-thioxanthenyl)-1,3-dicarbonyl compounds in 57-91 percent yields.The obtained 2-(9-xanthenyl)-1,3-dicarbonyl compounds are readily converted to 2-(9-xanthenylidene)-1,3-dicarbonyl derivatives using manganese(III) complexes or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone.The mechanisms for the formation of 9-substituted xanthenes are discussed on the basis of the reaction intermediates, the electron-donating substituent effect on the xanthene ring system, effect of additives, and comparison with a reaction of radical-trapping reagents.
