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Oxidation of triterpenoids methyl ursonate, acetylbetulone, and allobetulone with atmospheric oxygen in the presence of ButOK in ButOH afforded the corresponding 2,3-diketo derivatives in 90-97% yields. These derivatives exist predominantly as tautomers containing the enolized keto group at the C(2) atom. Their reactions with o-phenylenediamine gave rise to the corresponding quinoxalines in 85-95%...
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